Royal Society of Chemistry Environmental Chemistry Group (www.rsc.org/ecg)

February 2016

ECG Bulletin

Nanomaterials in the environment. Following our successful Distinguished Guest Lecture and Symposium in 2015, we publish a meeting report and three articles on the implications of in-creasing nanoparticles use on the envi-ronment (pp. 11-20). Eugenia Valsami-Jones, the 2015 Distinguished Guest Lecturer, warns that laboratory studies only partially capture the complexity of real environments (pp. 13-15). Environmental Briefs. We continue our series of short updates on im-

portant environmental techniques with articles on remote sensing of thermal IR radiation to determine atmospheric composition (Harjinder Sembhi, pp. 21-22), and on biotic ligand models for predicting trace metal concentrations in the water column (Adam Peters and Graham Merrington, pp. 23-24). Also in this issue. Two book reviews discuss, respectively, the historical pro-cesses that brought our planet into the Anthropocene (p. 6) and the pros and cons of fracking (p. 7).

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 2

ECG Bulletin ISSN1758‐6224 Print 2040‐1469 Online Published by the Royal Society of Chemistry’s RSC Environmental Chemistry Group ECG , BurlingtonHouse,Piccadilly,LondonW1J0BA,UKExecutiveEditorJuliaFahrenkamp‐Uppenbrinkecgbulletin@hotmail.co.ukProductionEditorsRowenaFletcher‐Wood,ScienceOxfordrowena. letcher‐wood@scienceoxford.comTomSizmur,UniversityofReadingt.sizmur@reading.ac.ukEditorialBoardJoBarnes,UniversityoftheWestofEngland,BristolBillBloss,UniversityofBirminghamZoëFleming,UniversityofLeicesterIanForber,Scienti icAnalysisLaboratoriesCeciliaFrench,Cran ieldUniversityBrianGraham,NationalHouseBuildingCouncil,MiltonKeynesMartinKing,RoyalHolloway,UniversityofLondonSteveLeharne,GreenwichUniversityRupertPurchase,HaywardsHeathRogerReeve,UniversityofSunderland

Environmental Chemistry Group www.rsc.org/ecg,Twitter:@RSC_ECG,Facebook:RSCEnvironmentalChemistryGroupChair:MartinKing,RoyalHolloway,UniversityofLondonm.king@es.rhul.ac.uk Vice‐Chair:BillBloss,UniversityofBirminghamw.j.bloss@bham.ac.uk HonorarySecretary:ZoëFleming,UniversityofLeicesterzf5@leicester.ac.uk HonoraryTreasurer:IanForber,Scienti icAnalysisLaboratories ianforber@yahoo.co.uk ThisandpreviousissuesoftheECGBulletinareavailablewithoutchargeatwww.rsc.org/ecg.ForECGmembershipdetails,visitwww.rsc.org/MembershipECGBulletin©TheRoyalSocietyofChemistry–EnvironmentalChemistryGroup2016RegisteredCharityNumber207890

Contents Chairman’sreport:NewsfromtheECG,byMartinKing 3

Article:Fromenvironmenttooutreach,byRowenaFletcher‐Wood 4

TheECGInterview:TomSizmur 5

Bookreview:TheShockoftheAnthropocene,byJuliaFahrenkamp‐Uppenbrink 6

Bookreview:Fracking:IssuesinEnvironmentalScienceandTechnologyNo.39,byCeciliaFenech 7

Meetingreport:Contaminatedlandandextremeweatherconditions,byRowenaFletcher‐Wood 8

Meetingannouncement:Geoengineeringtheclimate:2016DistinguishedGuestLectureandSymposium 10

Meetingreport:Nanomaterials—environmentalremediantsortoxicants?,bySteveLeharne 11

2015DGLarticle:Nanomaterials:Smallparticles,bigtrouble?,byEugeniaValsami‐Jones 13

Article:Overcomingnanoecotoxicologicaleffectsforsustainableremediationofnanomaterials,

byDeboraF.Rodrigues 16

Article:Arestandardecotoxicologicalbioassaysablessingoracurse?,byDavidSpurgeon 18

ECGEnvironmentalBriefNo10:Thermalinfraredremotesensingoftheatmosphere,byHarjinderSembhi 21

ECGEnvironmentalBriefNo11:Bioticligandmodels,metalbioavailabilityandregulatoryapplication,

byAdamPetersandGrahamMerrington 23

The ECG Bulletin is printed on paper made from wood pulp sourced from sustainable forests, and is suitable for archival storage. This issue of the ECG Bulletin was printed by Prizmatic Print Solutions, www.prizmatic.co.uk; 01444 239000.

Coverimage:Goldnanoparticlesimagedwithatransmissionelectronmicroscope.Credit:GeorgyShafeev/Shutterstock

In 2015, the Environmental Chemistry Group organised several well-attended meetings, including the Distinguished Guest Lecture and Symposium on nanomaterials in the environment. We also celebrated the 20th anniversary of the ECG Bulletin and continued to expand our ECG Environmental Briefs series. 2015 ECG Distinguished Guest Lecture OurDistinguishedGuestLectureandSymposium,heldon24 June 2015, was entitled “Nanomaterials environmental remediants or toxicants?” Organised byRowenaFletcher‐WoodandtheECGcommittee,thiswell‐attendedmeetingincludedtalksbyDaveSpurgeon,DebraRodrigues and Iseult Lynch. In her Distinguished GuestLecture, Éva Valsami‐Jones University of Birmingham highlighted the complexities of assessing theenvironmentalimpactsofnanoparticlesandoutlinedhowprogresscanbemade.Areportofthemeetingandarticlesfromthespeakersareincludedinthisissue.The2016ECGDistinguishedGuestLecturewillbeheldon22March 2016. The theme this year is ‘GeoengineeringtheClimate’,andtheDistinguishedGuestLecturerisAlanRobock Rutgers University . Our three supportingspeakers are equally excellent Joanna Haigh, ImperialCollege, David Santillo, Greenpeace and MichaelStephenson,BritishGeologicalSurvey .Moreinformationmaybefoundattinyurl.com/om755cqandonp.10ofthisedition.Booksoonasplacesarelimited.

Other meetingsTwo excellent meetings were co‐organised by yourcommitteemembersthisyear:theNewDevelopments inthe Analysis of Complex Environmental Matrices 2015meetingwasheldon6February2015atBurlingtonHouseinLondon.Andon4March2015,consultants,regulatorsand scientistsmet in Shef ield for a one‐daymeeting onEmerging contaminants in waters and soils, practicalconsiderations – sampling, analysis and consequences.Meeting reports may be found in the July 2015 ECGBulletin tinyurl.com/ecgb2015‐07 . Suggestions frommembers of possible meeting topics are welcome andshould be directed to the ECG Secretary, Zoë Flemingzf5@leicester.ac.uk .

ECG BulletinThe ECG Bulletin is an exciting mix of articles onenvironmental concerns,meeting reports, environmentalbriefs, and ECG news. The January 2015 anniversaryedition included special articles on the past 20 years ofenvironmental chemistry and of the Bulletin seetinyurl.com/http‐ecgbarchive .

ECG Environmental BriefsWiththelatestarticlesonpages21and23ofthisedition,our Environmental Briefs series now contains elevenarticles.Wehavehadmuchpositivefeedbackaboutthesebrief, informative, expert‐written articles that explainwidelyusedtechniquesandapproachesinenvironmentalchemistryinanaccessibleway.Allarticlesmaybeviewedanddownloadedfromtinyurl.com/pun38tf.Iwaspleasedto ind that if you Google “Environmental Briefs”, ourseries comes out as the top hit. I also understand theyhavebeenused intheteachingofat least twouniversityenvironmental science courses. All members areencouragedtoletusknowwhattopicsyouwouldlikeustocover.

Funding the ECGAll of the above happens through the work of yourcommitteemembers,whomeetfouror ivetimesayearinBurlingtonHouse.A recent reviewof InterestGroupfunding means that our funding will be signi icantlyreduced. Unfortunately, under the new formula wewould not have suf icient budget to cover our annualtravel.AswearethelargestRSCinterestgroupandoneof the most active, we are engaging with staff at theRoyal Society of Chemistry on how we might securemorefundingtosupportallourmeetingsandactivities.

ECG committee changesAsreportedinapreviousECGBulletin,thecommitteehasrecently changed. I would like to particularly thank theoutgoing chair, JamesLymer, forhishardworkover thepast decade as member and recently chair of the ECGcommittee. Jameshasorganisednumerousmeetingsandprovided close links with the toxicology special interestgroup; he was also a regular contributor to the ECGBulletin. Iwould also like to thank JoBarnes andCeciliaFenech, respectively, for their contributions as ECGTreasurers.

MartinKing,ECGChair

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 3

Chairman’s report

News from the ECG

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 4

Researchers are best placed to explain scientific issues to interested members of the public. In recent years, I have been involved in several activities that brought environmental science to a wider audience. In May 2014, I was part of a team organisingCambridge’s Pint of Science on Earth and Environment,sponsoredbytheRSCandUniversityofCambridge.Ourspeakers included Professor Eric Wolff a former ECGDistinguishedGuestLecturer fromtheBritishAntarcticSurvey, whose research into isotopic abundances andimpurityphasesinicecoresallowshimtodigdeepintoearth and climate history. The lectures were part of athree‐daysciencegatecrashofpubsincitiesaroundtheworld thatwas started in 2012 and runs annually seepintofscience.co.uk/about . Participating pubs convertbackrooms into informal lecture theatres for just threenights, where researchers come to give public talks onwhattheydo.In2015,PintofScienceexpanded,andforthe irsttimetookplaceinBirmingham,whereIwasthenliving.Pubsacrossthecitycentre—including the cosy upstairs gin bar of thequirky Jekyll and Hyde, where CaféScienti ique is held—came alive withinspirational ideas, discussion and narrativesof scienti ic venture. The distribution,intensity and ongoing demand for Pint ofScience show how willing the public are toengage in science, especially with a beer in hand. ThenextPintofScienceFestivalwilltakeplacefrom23to25May2016.Lookoutforeventsnearyou.Early career researchers can also share their researchthrough a range of channels. One such channel is theBrilliant Club www.thebrilliantclub.org , an award‐winning organisation that pairs PhD students andpostdoctoral researchers with small groups of schoolchildren aged 10 to 18 from state schools from whichfewstudentsenterhighlyselectiveuniversities.Thegoalis to increase the numbers of children going to highlyselective universities from these schools. Theresearchers teach a short, intense course on their ownresearch topic and set a inal assignment highlychallengingforthechildren’sagegroup.In2015,Itaught“Environmental Science: Controversy and Chaos” to 24Birmingham pupils in years 9 and 10, blasting through

environmentalissuesthatincludedthenuclearindustry,biofuels, CO2 storage, human impacts on climate,measuring the past climate, and plastic waste.We alsotalkedaboutsocialissuessurroundingtheenvironment,such as human and economic bias, uncertainty andextrapolation, the value of consolidating evidence, therole of the media, science in advertising, and what“natural” really means. Debate‐focussed, the coursetransitionedfromteacher‐ledtostudent‐led;bytheend,I simply gave them some text or a video and watchedwhattheydidwithit.Intheir inalassignment,thepupilsachieved a range of grades from 3rd class to someimpressive 1st classes. Early career researchersinterestedintakingpartinthisprogramcangetintouchviaemail hello@thebrilliantclub.org .Morerecently,IhavebeenexperimentingwithmybrandnewScienceJigsaws.Pictureskindlyprovidedbyfriendsandresearchersarelaidontowoodenbasesandcutbyfamily‐run Puzzleplex puzzleplex.co.uk/ , who createunusual shapes rather than the usual squares to makejigsaw building more challenging and thoughtful.Amongstmy small customcollectionare suchpieces as

“TheSun”and “ClimateChange”.Apicturetaken by my uncle and keen naturephotographer, Kevin Meehan, “ClimateChange” shows a range of spiky icebergsalong the coast of Iceland. I’ve tried thejigsawsonadultsandchildren,forexample

at postgraduate training days and after‐school clubs,invitingquestionssuchas“Howfast isthe icemelting?”or asking them what they know already. As land icemelts, landheightrisesat1.4inchesperyearaccordingto global positioning system measurements. But whatdoes this mean to young people, and how do theyunderstandthechangingclimatethroughstories,images,and science? Motor learning—doing a jigsaw whilstgatheringinformation—isagoodwaytointegrateideasand creates long‐term sensory memories; jigsawlearningcanbeadaptedtoanyaudience.

Article

From environment to outreach Rowena Fletcher-Wood (Science Oxford, rowena.fletcherwood@gmail.com)

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 5

ECG committee member Tom Sizmur is a Lecturer in Environmental Chemistry at the University of Reading. He tells us about his career as a soil chemist. What inspired you to become a scientist? I havealwaysbeeninterestedinhownatureworks.Thenaturalworld is fabulouslycomplicatedandthere are so many interacting factors that govern thefunctioning of environmental systems. As a scientist, Istrivetounderstandthesefactorssothatwecanpredictfuturechangestoourenvironment.

How did you come to specialise in soil chemistry? During my undergraduate degree, Ibecameinterestedinhowsoilsworkedandhowtheyareaffected by environmental pollutants. I still ind itamazing that, as a scienti ic community, we seem toknowmoreaboutthestars intheskythanwedoaboutthe biogeochemical interactions that occur in the soilbeneathourfeet.Irecognisedearlyonthattherewasanurgent need to better understand how soils delivernutrients to plants and how they are able to ilter ordegradepollutants.Ihavededicatedmyprofessionallifeto understanding how organisms interact with thechemical and physical constituents in the soil. Thisknowledgewillhelptounderstandhowtheyareabletosupportlifeaboveground.

Could you describe your current job? I spend roughly half of my time teaching BSc andMScstudents the fundamental concepts that underpinenvironmentalchemistryandenvironmentalpollution.Ialso teach in the ield so students can exploreenvironmentalissuesbeyondthelaboratoryandpractisecollecting and analysing samples. The idea is to helpthem develop the skills they will need to becomeenvironmental consultants, regulators and researchscientistswhentheygraduate.Theotherhalfofmytimeis spent on research into how organisms interact withtheirchemicalandphysicalenvironment.Inmuchofthisresearch I have focused on how earthworms engineerthe soil environment in which they live. Earthworms

createburrowsanddepositcastsonthesoilsurface.Theseprocesseschangethebiogeochemistry of the soil. DuringmyPhD, I showed that the mobility ofmetals in soil increases after passagethroughtheearthwormgut.

What advice would you give to anyone considering a career in environmental chemistry? Don’t focus on tryingto solve a particular environmentalissueoransweraspeci icquestionthat

is close to your heart. The likelihood is that as yourcareer develops, new and interesting challenges willemerge.Forexample,whenIwasaBScstudentclimatechangewas topof theagenda.Now, issuessurroundingsustainableintensi icationoffoodsupplyarereceivingalot of attention. The skills required to address bothissues are similar, because they are both complexinterdisciplinary environmental issues. The key tosuccess is to develop a set of capabilities that can beappliedtowhateverthenextbigchallengeis.

What are some of the challenges facing the environmental chemistry community? Translating research into practicalsolutionstoenvironmental issuesisabigchallenge.Formanyyears,environmentalscientistshaveestablishedareputation for identifying problems rather thandevelopingsolutions.Thishasresultedindisengagementwithindustry.Wenowneedtoworktogethertodevelopsolutionstoenvironmentalissues.

What is the most rewarding aspect of your career so far? I still get a buzz whenseeing scienti ic data for the irst time. I often cannotwait to plot it on a graph to see if it supports thehypotheses we are testing. There is nothing morerewarding thanmaking a discovery and, for amoment,beingtheonlypersonintheworldwhoknowsit.

If you weren’t a scientist what would you do?Sincebecomingalecturer,Ihavediscovereda passion for teaching. It is very ful illing to mentorstudentsintheirlearning.IfIhadnotbecomeascientist,thenIhopeIwouldhaveconsideredacareerinteaching.

The ECG Interview: Tom Sizmur

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 6

Book Review

The Shock of the Anthropocene Julia Fahrenkamp-Uppenbrink (ecgbulletin@hotmail.co.uk)

Have we entered a new epoch in which humans dominate geological processes at the Earth surface? The pervasive impacts of humans on all aspects of the environment show no sign of abating, with potentially devastating consequences for humans and wildlife. The term for this epoch—the Anthropocene—appears to suggest that it is an inevitable outcome of our growing population and advanced state of civilization. In The Shock of the Anthropocene, historians Christophe Bonneuil and Jean-Baptiste Fressoz show that far from inevitable, today’s situation results from political and economic choices made despite concerns about the environmental impacts raised since the early days of the industrial revolution. Ade iningfeatureoftheAnthropoceneistheriseincarbondioxide and the resulting climate change; other factorsinclude the rapid loss of biodiversity and changes inbiogeochemical cycles as a result of arti icial fertilisation.However,TheShockoftheAnthropocenedoesnotprovidesimpleanswersorasinglenarrativeforhowtorespondtotheseinterrelatedcrises.Thisisentirelyintentional,astheauthorsaim toportray themanydifferentways inwhichour current epoch canbeunderstoodand illuminated. Inthe process, they use alternative terms for theAnthropocene that initially seem cumbersome butarguably better capture the driving forces behind theenvironmentaldestructivenessofmodernlife.One such term, the Thermocene, is used to chart thehistory of energy use. In the early 19th century, largehydraulicprojectsprovidedenergyforthegrowingtextileindustryinnorthernEnglandandScotlandatlowerpricesthanforcoal.IntheUS,state‐of‐the‐artwindmillsplayedakeyroleintheagriculturaldevelopmentoftheMidwestinthe 19th century, while the 1920s and 1930s saw thedevelopmentofsolarwaterheatersandlow‐energyhomesthatprovided largepotentialcostsavings.Yet, fossil fuelswonout intheseandmanyothercases,withsolar,waterandwindenergyreducedto“alternativeenergies”thatareonlynowseeingarenaissance.BonneuilandFressozargue

thatthereasonswereoftenideological and politicalrather than technological.In the case of the Britishtextile industry, coalprovided a decentralisedsource of energy that didnot require coordinationbetween theentrepreneursof the early industrialrevolution. Wind and solarpower in theUS lostout inthe 1950s, when powerfulelectricitycompanieshadastronginterestinextendingthe national grid to allconsumers.Other chapters explore the role of war and the militarytheThanatocene ,consumerism thePhagocene ,andtheprevalenteconomicsystem theCapitalocene inbringingabout the Anthropocene. But perhaps most interestingfromthepointofviewof environmental chemistry is thehistory of environmental warnings that went unheeded.Today’s environmental scientists are far from alone intheir concern for the environment. As early as 1778,George‐Louis Buffon wrote that “the entire face of theEarth today bears the imprint of human power” andwarned nations not to “use everything up withoutrenewing anything.” And in 1913, Edmond Perrier askedwhether “we have the right tomonopolise the Earth forourselvesalone,andtodestroyforourpro it…everythingit has produced that is inest andmost powerful.” Thesewordsretaintheirrelevancetoday.Rather than considering ourselves the masters of ourenvironment, humans will need to, in Bonneuil andFressoz’s words, place nature “at the heart of ourconception of freedom.” Given today’s dominantconsumerism,thismayseemunlikely.Butbylayingoutthemany factors and circumstances that brought about ourcurrentpredicamentdespiteknowledgeofthedetrimentaleffects,TheShockoftheAnthropocenehelpsthereadertoconceiveofadifferentfutureinwhichnatureisnolongerseenasseparatefromhumanity.TheShockoftheAnthropocene,ChristopheBonneuilandJean‐BaptisteFressoz,VersoBooks,London,2016,pp.320,ISBN:1784780812,9781784780814.

Antiqueaermotorwind‐mill.Credit:KennethKiefer/Shutterstock

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 7

Shale gas hydraulic fracturing (fracking) is considered by some to be essential for securing our energy future and increasing the energy mix, while others consider it highly damaging to the environment. Fracking is thus both controversial and topical, particularly in the UK, where it is not yet practised on a commercial basis, but is receiving high-level support. This book, edited by R. E. Hester and R. M. Harrison, aims to outline both sides of the debate with contributions from scientists, policymakers, and industry. Eachoftheeightchaptersisastand‐alone piece written by a differentauthor or group of authors, allowingthe reader to get a deeperunderstanding of a speci ic angle ofthe debate. The book as a wholeprovides a comprehensiveunderstanding by combining moretechnical sections e.g. includingdetails of fracking operations andhydraulic wells and less technicalpolicy sections related to shale gasoperations around the world. Eachchapter is also well‐referenced,enabling readers to explore the concepts further. Thismakes the book accessible to readers with differingpurposes,fromapassinginterestinthefrackingdebatetoa requirement for a deeper understanding of moretechnicalaspects.Thebookstartswithanoverviewoftherolethatshalegasmay play in securing our energy future. As Peter HardyUKInstituteofGasEngineers explains,frackingiswidelytoutedastheanswertodepletednaturalgasdepositsasitenablestheeconomicalextractionofunconventionalshalegas. However, fracking brings with it a number ofenvironmental, human health, and safety concerns.

Concerns relate to the chemicals used in the frackingprocessandtheirdisposal,greenhousegasemissions;andthe hydraulic fracturing process itself, which has beenlinkedtoearthquakesinthevicinityofsuchactivities.The following chapters explore the economic impacts ofshale gas in the USA F. Taheripour et al., PurdueUniversity ; considerations for shale gas and shale oilexploration I.Scotchman,Statoil ;climatechangeimpactsJ. Broderick & R. Wood, Tyndall Centre for ClimateChange Research ; hydrogeological aspects of UKextraction R.Wardet al.,BritishGeological Survey ; theAustralian experience with coal seam gas recovery A.Randall,UniversityofSydney ;andChineseprospectsforshalegas S.Jiang,UniversityofUtah .Inthe inalchapter,T.Bosworth FriendsoftheEarth arguesthatshalegasis“unburnableandunwanted”asitsenvironmentalconcerns

far outweigh any potential bene it.Although the book has a UK focus,chapters relating to the experiencesindifferentcountries USA,Australiaand China broaden its scopeconsiderably. These chapters alsohighlight the speci ic considerationsthat may make shale gas hydraulicfracturing suitable or unsuitabledependingonthecircumstances.TheuseofshalegasintheUKisstillin its infancy, and a number ofhurdlesremaintobeovercomepriorto commercial success. How farshould theUK go to overcome these

hurdles while taking into account health and otherconcerns? What role should shale gas play in the UK’senergy mix—a key energy source for the foreseeablefuture,atransitionalfuel,ornoneatall?Thebookdoesnotgiveanswerstoanyofthesequestions,butratherprovidesan illuminating overview of both sides of the debate,

allowingthereadertoformaneducatedopinion. Fracking: Issues in Environmental Science andTechnology,No.39,editorsR.E.HesterandR.M.Harrison,Royal Society of Chemistry, Cambridge, 2015, pp. xvii 228,ISBN:978‐1‐84973‐920‐7.

Book Review

Fracking: Issues in Environmental Science and Technology No. 39 Cecilia Fenech (Cranfield University, c.fenech@cranfield.ac.uk)

Book Review

Fracking: Issues in Environmental Science and Technology No. 39 Cecilia Fenech (Cranfield University, c.fenech@cranfield.ac.uk)

Credit:Serz_72/Shutterstock

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 8

A one-day meeting on “Contaminated Land and Extreme Weather Conditions” was held in the CIRIA (Construction Industry Research and Information Association) offices in London on 29 June 2015. Attended by ca. 35 scientists and policymakers, the meeting highlighted key concerns about contaminated land that had been overlooked in the past and showed that fundamental changes must be made to industry structure and the paradigm of safety assessment. The meeting began with a talk by the CIRIA chairman,Mike Ellis, who spoke about the urban soils of centralLondon.Heexamined thedif icultyfoundseparating“soil” from“dust”and considered how the spatialdistributionofcontaminantsvariedwith the nature of contaminants.For example, lead and arseniccorrelate not only with urbandensity, but also with the naturalbackground, determined by rocktypes in the area. He furthermentioned a 1:1 observed correlation betweenbioavailability and bioaccessibility of contaminants, andqueried the validity of separating these concepts. Otherpoints included the dif iculty found in assessing hazardona reasonable timescale.Forexample,aNewOrleansstudyhasshowna22‐yearlagbetweenatmosphericleadpollution and its consequences upon human health andbehaviour—in this example, an increased aggravatedassaultrate.Subsequentspeakersdiscussedcontaminatedlandinthecontext of sustainable development and highlighted thereasons why predicting environmental changes andminimising the detrimental effects of development arenot straightforward. For example, they touched on theuncertaintyinmodelpredictionsoffutureCO2emissions

and the different drivers for fossil fuel reduction atregionalandnationalscales,suchas local loodriskandthe cost of technological changeover. Correctidenti ication of catchments for remediation treatmentrequires knowledge of factors such as wind speed anddirection,historicallanduse e.g.mininglegacy ,andpH‐dependent soil leaching. This highlights the intricacy ofintegrated risk analysis. Good sources of informationinclude the research‐policy partnership LWEC LivingwithEnvironmentalChange 1 andtheEuropeanIPPCbureau Integrated Pollution Prevention and Control 2 .BrionyTurner ARCC,UKCIP andJoanneKwan CIRIA highlighted the absence of contaminated land andremediation strategies in the government’s ClimateChangeRiskAssessment CCRA report 3 .Theycalledfor a statutory reporting process to develop a body ofdata,aswellassharedlearningandguidancedocuments.With funding fromtheEPSRC, theUKCIPARCCnetwork

aims to ill these gaps. Forexample, increasing rivererosion under climate changemayreleasemorecontaminants.Yet, contaminantmobility isnotcurrentlymonitored in the ieldand is in fact very dif icult tomonitor, because contaminantscross river catchments andrequire very sensitive detection

as they are diluted and dispersed. The speakers alsoreported on STEM workshops in schools that educatepupilsabouttheimpactsofclimatechange.OliverLancaster Wales&WestUtilitiesLtd focussedonextreme weather, the implications of intense loodingand protection, and policy and practices involvinggroundwater.Lancasterexpressedconcernoverhowweassesscontaminatedlandandclassifycontaminantsanddevelop conceptual site models. Safety assessmentsgenerally include the caveat “based on current site useand land conditions,” but these sitesmay be subject tovariation under continuing climate change and varyingweather patterns. Future increases in rainfallmay eveninvalidatesafetyassessments,although,Lancasteradded,“Giventheuncertainty,itwouldbeaveryboldconsultant

Meeting report

Contaminated land and extreme weather conditions Rowena Fletcher-Wood (Science Oxford, rowena.fletcherwood@gmail.com)

A New Orleans study has shown a 22-year lag between

atmospheric lead pollution and its consequences upon

human health and behaviour.

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 9

tosuggestclimatechange‐drivenremediationmeasures”.Taking the aspect of looding further, Chris MeakinWorleyParsons argued that looding causes andexacerbatescontamination.Predictionsoffutureclimatechange include thepossibilityof an increase inextremeweatherevents.HecitedthewinterofDecember2013toFebruary2014asawarningexample;thewettestwinteron record, it saw storms and loods throughout thecountry. To address and mitigate the risk of loodingcontaminated land, Meakin called for a change inperception of conceptual models, such that riskassessments become lexible, living documents, ratherthan pre‐set standards, and greater uncertainty ismanagedwith incremental improvements asmore databecome available. For this to be successful, integratingknowledge and expertise across industries is vital.Potential problemswith this approach include theneedto risk‐assess changing methods, essentially producingriskassessmentsofriskassessments,andthesparsityofcurrent research and guidance. CL:AIRE ContaminatedLand: Applications in Real Environments , the ForestryCommission and CIRIA are existing bodies that arepursuingthiswork.StephenKidley CelticLtd. explainedthatknowledgeofgroundwater in theUK is patchy,with research laggingyears behind that on surface water. The study ofgroundwater is more complicated than that of surfacewaterandcannotbesimpli iedtotwodimensions.Rockpermeability plays a key role in the three‐dimensionalmovement of water. Not only does groundwater affect

the low, temperature andvolume of surface water, butalso its "rebound time" forrecovery after contamination.Previous estimations ofhydrological behaviour havebeen proven erroneous. Inone example, the estimatedtime for contaminated watertorecoverwas1year,buttheactualrecoverytimewasonly6‐8 weeks. It is questionablewhether we can validate anypredictions without greaterknowledge of why thisoccurred. Small errors in oneset of predictions can makehuge differences in thepremises of another, leadingtodisjointedmodelsbetweenindustries and academicexperts.

Trevor Howard EA provided the regulator’s point ofview,highlightingadditionaloutcomesofclimatechangeon contaminated land that areworthy of consideration.Under elevated temperatures and increased rainfall,organic matter breaks down faster and may producedifferent degradation products; the concentration ofmetaltoxinsinplantsmayalsovary,asmaythe ixationofmetals in soil,whichdependson soilpHand relativehumidity. On the streets, tar ismore likely tomelt, andtoxic metals such as mercury may vaporise fromcontaminatedsources.Bioticandchemicalprocesseswillalso change, but the extent towhich thiswill occur hasnot yet been estimated with any con idence. Becauseclimate change increases variability, the most variableclimates – like that in the UK – remain the hardest tomodel.This meeting is part of a series of events organised byCIRIA.ForfutureCIRIAeventsvisit:www.ciria.org/

References

1. www.rcuk.ac.uk/research/xrcprogrammes/lwec

2. http://eippcb.jrc.ec.europa.eu/reference/

3. www.gov.uk/government/publications/uk‐climate‐change‐risk‐assessment‐government‐report

Winter lood.FloodwatersthreatenthesurroundingroadsandhousingastheAfonTei iriverburstsitsbanksinDecember2013.Floodslikethiscanmobilisecontam‐inants.Credit:i4lcocl2/Shutterstock

2016 Distinguished Guest Lecture & Symposium: Geoengineering the Climate

A one-day symposium organised by the Environmental Chemistry Group of the

Royal Society of Chemistry

Where: The Royal Society of Chemistry, Burlington House, Piccadilly, London

When: Tuesday 22nd March 2016, 12.00 pm - 17.15 pm. Lunch is provided.

Confirmed speakers Professor Joanna Haigh (Imperial College London) “Climate geoengineering: some fundamentals”

Dr David Santillo (Greenpeace Research Laboratories) “Climate geoengineering: how could it be regulated?”

Professor Michael Stephenson (British Geological Survey) “Climate geoengineering: carbon capture and storage”

Distinguished Guest Lecture: Professor Alan Robock (Rutgers University) “Smoke and mirrors: not the solution to global warming.” ProfessorRobockwilldeliverthe2016ECGDistinguishedGuestLecture,speakingonsolarradiationmanagementSRM byinjectingparticlesintothestratosphere,brighteningclouds,orblockingsunlightwithsatellitesbetweenthesunandEarth.IftherewereawaytocontinuouslyinjectSO2intothelowerstratosphere,itwouldproduceglobalcooling,stoppingmeltingoftheicecaps,andincreasingtheuptakeofCO2byplants.Althoughnosystemstoconductstratosphericgeoengineeringnowexist,acomparisonofdifferentproposedinjectionschemes,usingaeroplanes,balloons,andartillery,showsthatputtingsulfurgasesintothestratospherewouldbeinexpensive.Butthereareatleast27reasonswhystratosphericgeoengineeringmaybeabadidea.TheseincludedisruptionoftheAsianandAfricansummermonsoons,reducingprecipitationtothefoodsupplyforbillionsofpeople;ozonedepletion;nomoreblueskies;reductionofsolarpower;andrapidglobalwarmingifitstops.Furthermore,thereareconcernsaboutcommercialormilitarycontrol,andseriousdegradationofterrestrialastronomyandsatelliteremotesensing.Globaleffortstoreduceanthropogenicemissions mitigation andtoadapttoclimatechangeareamuchbetterwaytochannelourresources.

Delegate Rates Non‐membersofECG:£35 £25earlybirdratebefore12Feb

ECGmembersandconcessions:£30 £20earlybirdratebefore12Feb

Alimitednumberoffreeplacesareavailableformembers,e.g.theunemployed.Ifyouwouldliketoapplyforone

oftheseplaces,pleasecontactthemeetingorganiser.

Toregisteronline,pleasevisitevents.rsc.org/rsc/833/registerbefore14thMarch.Delegatefeesarenon‐

refundable.Forenquiries,contactthemeetingorganiser,RowenaFletcher‐Wood ecg.dgl@gmail.com .

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 10

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 11

Recent reports released by Research Councils UK and the Royal Society of Chemistry have stressed the importance of nanoscience and technology to the long-term prosperity of the UK. On 24 June 2015, a half-day symposium convened by the ECG considered the environmental challenges and benefits provided by the synthesis and use of nanomaterials. The symposium, attended by about 60 people, also provided the occasion to present the ECG’s DGL medal to Professor Valsami-Jones from the University of Birmingham. David Spurgeon Centre for Ecology and Hydrology,Wallingford, UK examined thebene its and problems associatedwith the use of standard tests forassessing nanomaterial ecotoxicity.Standard tests are used to ensureinter‐laboratory data comparability,and are approved inter alia by theOECD. Many commercially usednanomaterials end up in sewagesludge seethephotobelow ,whichis spread onto soils. Thus,nanomaterial contamination is veryoften a soil contamination issue.Standard tests exist for examiningthe ecotoxicity of nanomaterials insoils.Thesetestsrelyupontheuseofa limited number of test speciesnormally adults ; a standardmedium; and standard testconditions to examine a particular

toxicologicalend‐point normallydeath overade ined,short‐term exposure period. The speaker showed thatsuchstandardisedtestsveryoftenfailtoidentifycriticalfactorsthatmayaffecttoxicityindifferentenvironmentsandoverdifferenttimescales.Forexample,soilpHandorganic matter composition attenuate nanoparticletoxicity in soils. One study found that silvernanoparticles become increasingly toxic to theearthworm Eisenia fetida as they changed with timeaging . Because standard tests rapidly generate dataand provide reliable information for initial riskassessments, they are the toolsof choice for regulatoryrisk assessment. However, such tests restrict thediversityofdataavailableforriskmodellingandcanfailtoaddresskeyendpointsandeffects.Non‐standardtestscan be important for detecting speci ic outcomes andvalidatinghypotheses.Iseult Lynch University of Birmingham was a lastminutereplacementforDrTomScott,whowasunabletoattend. She focussed on nanoparticle interfaces, whichare key to the environmental fate and behaviour of

Meeting report

2015 Distinguished Guest Lecture and Symposium: Nanomaterials—environmental remediants or toxicants? Steve A. Leharne (University of Greenwich, s.a.leharne@gre.ac.uk)

Wastewatertreatmentplant.Nanoparticlesoftenendupinsewagesludgethatisspreadontosoils.Credit:SKY2015/Shutterstock

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 12

nanoparticles. Nanoparticleinterfaces have high surfaceenergies. Molecular adsorptionlowers surface energy and therebypassivatestheinterface.Humanscantake up nanoparticles by ingestion,inhalationorabsorptionthroughtheskin. After entering the body,nanoparticles are surrounded bybiological luids. Binding ofbiomolecules to the nanoparticlesurface can confer biologicalrecognition. The resultantbiomolecule/nanoparticlecomplexescan act as “Trojan Horses” for thetransport of contaminants. In theenvironment, nanoparticles are alsoable tobindorganicmatter.Bindingof biological or organic moleculesmay stabilise nanoparticles againstaggregation ormay promote it. Therange of effects associated withmolecular bindingmust be assessedto properly understand theenvironmental fateand toxicologicalpropertiesofnanoparticles.Debora Rodrigues University of Houston spoke abouther group’s work on using carbon‐based single‐walledandmulti‐wallednanotubesandgrapheneandgrapheneoxideforthesustainableremediationofwastewater seephotoonthepreviouspage .Themaingoalistoproducecheapnanomaterialsthatarereadilydispersedinwaterand that have reduced human cytotoxicity. In toxicitymeasurementsagainsthumancell lines,grapheneoxidefunctionalised with poly N‐vinyl carbazole PVK showednotoxicity,andcarbonnanotubesfunctionalisedwith PVK showed reduced toxicity compared to thenanomaterials without PVK. Functionalisation of thecarbonnanomaterialswith PVKpermits the removal ofmetalionssuchasleadunderappropriatepHconditionspH5 .Thesamematerialswereabletoinhibitmicrobialactivity.Thespeakeralsoshowedthatthefunctionalisednanomaterials can be attached to membrane ilters.Filters containing PVK‐functionalised carbon nanotubeswere effective in inactivating/killing bacterial cellsthroughcelldisruption,resultinginbetterqualitywaterthough possibly not of drinking water quality .Unfortunately it remains dif icult to regenerate thenanomaterials.Thesematerialsshowpromisebutissuesofcostandlarge‐scaleproductionneedtobeaddressed.The meeting closed with the 2015 Distinguished GuestLecture by Eugenia Éva Valsami‐Jones University ofBirmingham . She began by outlining the perceived

economicpotential of nanomaterials,which arises fromtheir novel properties, including quantum con inement,surface plasmon resonance and superparamagnetism.However, their toxicity is dif icult to predict because ofmajor challenges of detection and characterisation. Forexample, nanoparticle size, shape and structure isaffectedbyaging.Moreover,characterisationneedstobeundertakeninrelevantmedia.Aparticularchallengeliesin assessing the uptake of metals from metal‐basednanomaterials see micrograph at realistic exposurelevels.Toaddressthesechallenges,ÉvaValsami‐Jonesoutlinedthe use of nanomaterials that have been eitherisotopically or luorescently labelled. In one study,labelling permitted an assessment of zinc assimilationviadietaryexposure.Oneconclusionfromthisworkwastheabsenceofany“off‐the‐scale”toxicityassociatedwithnanoparticles. Nanoparticles may be internalisedthrough a range of biological mechanisms, includingphagocytosis for largeparticles, endocytosis for smallerparticles, and macropinocytosis from luids. Surface‐coated nanoparticles can also be taken up by biologicalcells.Computermodellingshowsthatsurfaceenergyfallswith increasingnumbersof atoms,but this reduction isnot smooth.Thus,apparent inconsistencies in reactivitydatawithsizemayarisefromgenuinechangesinsurfacepropertieswithparticlesize.

Goldnanoparticlesimagedwithatransmissionelectronmicroscope.Credit:GeorgyShafeev/Shutterstock

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 13

Nanotechnology is proliferating in all aspects of modern life. Novel nanometre-scale materials are used in every-day products from cosmetics and medicines to fitness and food products. Research into the safety of these materials is lagging behind their technological applications, leading to concerns that products become available without due environmental and human health safety considerations. Furthermore, research into nanomaterial safety is marred by controversy. Consensus is lacking on laboratory methodologies, long-term studies are few, and approaches to develop nanomaterial groupings and models of activity are in their infancy. Thus, nanomaterials, despite their small size, are the source of big trouble.

It has been more than 10 years since the term“nanosafety”, describing research into the potentialhealth and environmental threats from nanomaterialsand the development of safer alternatives “safe bydesign” , became a regular feature of the scienti icliterature. Key to the recognition of the need for suchresearch was an authoritative report published by theRoyalSocietyand theRoyalAcademyofEngineering in2004 1 ,which presented in technical detail concernsabout the risks of nanotechnology, particularly freeengineered nanomaterials. Other major reviewsfollowed, including EPA’s NanotechnologyWhite Paperin 2007 2 and a report by the Royal Commission onEnvironmentalPollution in2008 3 thatdescribedtheissuesandlackofprogresssincetheRS&RAEreport 1 .In 2012, the Royal Society of Chemistry published itsownreviewofnanosafety,particularly focussingonthedif iculties in developing legislation in the lack ofsuf icientandsoundscienti icevidence Figure1 4 .Concerns about the need for research, not only tounderstand potential hazards from nanomaterials, butalso to develop an appropriate framework to regulatethem, are well justi ied. An estimated 500 to 2,000nanomaterialswereplacedontheEUmarketatvolumes

ofatleast1tonne/yearintheperiod from 2012 to 20145 . This trend is likely tocontinue or even increase,and these nanomaterials areconsequently affected byregistration obligationsunder the chemicals’ safetyframeworkknownasREACHRegistration, Evaluation,Authorisation andRestriction of Chemicals ,which entered into force in2007. About 10% of thesenanomaterials are untreatednanoformsofabulkmaterialthatisalreadyregistered 5 .Testing these nanomaterialsandupdatingtheregistration

DGL Article

Nanomaterials: Small particles, big trouble? Eugenia Valsami-Jones (University of Birmingham, e.valsamijones@bham.ac.uk)

Figure 1.Wordle using the text from Nanotechnology Position Document, 2012

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 14

dossierswouldentailcostsofbetween€50millionand€315 million based on the proposed amendments toREACH guidelines for nanoforms. Additional costsbetween €6million and €38million per nanomaterialare expected for the 450 to 1,800 surface‐treatednanoforms variants around a common corematerial ,leadingtototalcostsofupto€600milliontobeborneby industry,mostly around 80% small andmedium‐sizedenterprises 5 .Developmentofaframeworkthatwould enable grouping and read‐across approachesvalidated for nanomaterials is therefore a majorresearchpriority.Inmy2015ECGDistinguishedGuestLecture,Ifocusontwo aspects of my research that are contributing toalleviatinguncertaintyonthesafetyofnanomaterials.

Stable isotope labelling Isotopic labelling of nanomaterials allows them to betracedintoxicityexperiments.Therearetwomainwaysoflabellingnanomaterials:Labelling relying on optical tracing. This involvesluorescent labels that are either grafted on thenanomaterial’ssurfaceor in thecaseof theverysmallquantumdots result from the nanomaterial’s intrinsicluorescence.Labellingrelyingonchemicaltracing.Here,thelabelisarareelementorisotopethatisusuallyintroducedduringnanoparticle synthesis and that is thereforehomogeneouslydistributedinthenanomaterial.Thedevelopmentofanumberofstableisotope‐labellednanomaterials enabled us to understand better theecotoxicityofnanomaterialsinexperimentsdesignedtosimulate realistic exposure of organisms tonanomaterials. For example, the development 6 andtesting 7 ofZnOnanoparticleslabelledwiththestableisotope 67Zn allowed us to show that zinc fromisotopically modi ied ZnO nanoparticles is ef icientlyassimilated by freshwater snails Figure 2 wheningestedwith food.Agglomerationof thenanoparticlesdid not reduce bioavailability and did not precludetoxicity.TheZnOnanoparticlesdamageddigestion.In more recent studies using isotopically labelled CuO8 and Ag 9 , we have demonstrated the increasedsensitivity that isotopic labeling provides. This isimportantbecause experiments cannowbeperformedatenvironmentallyrelevantconcentrations.Asaresult,exposures are more realistic and the true toxicitymechanisms can be identi ied and distinguished fromthe result of excessive dosing. In the case of Agnanoparticles, isotope mass balance calculations show

that labelling increases tracing sensitivities at least 40timesandpossiblyupto4000times,comparedtowhenthe label isnotpresent.This isdespitehaving touseasilver isotope 107Ag that is not particularly rareapprox.52%oftheelementstotalnaturalabundance .In the longer term, such labeling techniques could alsobe used to assign ownership of nanoparticles toparticular manufacturers, thus contributing to futurelegislativetraceabilityandaccountabilityneeds.

Uptake and internalisation Imaging of nanomaterials within organisms is alsohelpfulforunderstandingtheirenvironmentalimpacts.Ihavedescribedevidenceof the internalisationof silvernanoparticles by the polychaete Nereis diversicolorafter feeding on sediment spiked with eithernanoparticulate or aqueous silver 10 . The studyindicated direct internalisation of silver nanoparticles.Importantly, silver delivered in dissolved form wasinternalised via different routes than were silvernanoparticles, and the two typesof silverpreparationshaddifferentinvivofates.To establish mechanisms of uptake, we have usedpharmacological inhibitors to block speci ic uptakepathwaysthathavebeen implicated inthetransportofmetal nanoparticles and aqueous metal forms. Thisstudy, which focused on the mud snail Peringia ulvae,showed that nanoparticulate silver is taken up viamultiple pathways and that these pathways aresimultaneouslyactive 11 .Morerecently,wehavemonitored indetail thecellularuptakeoftitania TiO2 nanoparticlesintoA549 humanepithelial cells. This work demonstrated that thesurface chemistryofnanomaterialsplays a critical roleintheircellularinternalisation Figure3 .

Figure2.Limnaeastagnalis,thefreshwatersnailusedin the studies discussed here 7, 8 . Credit: Marie‐NoëleCroteau,USGeologicalSurvey

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 15

Outlook A large body of recentwork is contributing to a betterunderstanding of the safety of nanomaterials. Acutetoxicity effectsdiscovered todate are generally limited.However, the quantitative data from experimentsperformed in realistic and environmentally/biologicallyrelevant conditions remain too scarce to permitpredictions of nanomaterial toxicity. A framework toenable the regulation of nanomaterials has yet toemerge.

References 1. The Royal Society, London, Nanoscience and

Nanotechnologies: Opportunities and Uncertainties,2004. See www.nanotec.org.uk/report/Nano%20report%202004%20 in.pdf.

2. U.S. Environmental Protection Agency,Nanotechnology White Paper, 2007. Seewww.bdlaw.com/assets/htmldocuments/2007‐02_EPA_Final_Nanotechnology_White_Paper.pdf.

3. The Royal Commission on Environmental Pollution,Novel Materials in the Environment: The case ofnanotechnology, 2008. See www.gov.uk/government/uploads/system/uploads/attachment_data/ ile/228871/7468.pdf.

4. RoyalSocietyofChemistry,NanotechnologyPositionDocument, 2012. See www.rsc.org/images/Nanotechnology‐Position‐Consultation_tcm18‐223077.pdf.

5. EuropeanCommission,JointResearchCentreInstituteforHealthandConsumerProtection,Ispra,Italy,Examinationandassessmentofconsequencesforindustry,consumers,humanhealthandtheenvironmentofpossibleoptionsforchangingtheREACHrequirementsfornanomaterials,2013.Seeec.europa.eu/DocsRoom/documents/11913/attachments/1/translations/en/renditions/pdf.

6. A.D.Dybowska,M.‐N.Croteau,S.K.Misra,D.Berhanu,S.N.Luoma,P.Christian,P.O’Brien,E.Valsami‐Jones,EnvironmentalPollution159,2662011 .

7. M.‐N. Croteau, A. D. Dybowska, S. N. Luoma, E.Valsami‐Jones,Nanotoxicology5,79 2011 .

8. S.K.Misra,A.Dybowska,D.Berhanu,M.N.Croteau,S.N.Luoma,A.R.Boccaccini,E.Valsami‐Jones,Environ.Sci.Technol.46,1216 2012 .

9. A. Laycock, B. Stolpe, I. Roemer, A. Dybowska, E.Valsami‐Jones, J. R. Lead, M. Rehkaemper,EnvironmentalScience‐Nano1,271 2014 .

10.J.Garcia‐Alonso,F.R.Khan,S.K.Misra,M.Turmaine,B. D. Smith, P. S. Rainbow, S. N. Luoma, E. Valsami‐Jones,EnvironmentalScience&Technology45,46302011 .

11.F. R. Khan, S. K.Misra, N. R. Bury, B. D. Smith, P. S.Rainbow, S. N. Luoma, E. Valsami‐Jones,Nanotoxicology9,493 2015 .

Figure 3. Confocal re lectancemicroscopy, showing the effect of surfacemodi icationon theuptake of titaniumdioxide titania nanoparticlesbyA549cells.Dispex‐coatedtitaniaparticlesremainoutsidethecell left ,whereasPVP‐coatedtitaniananoparticlesareinternalised. right Credit:AbdullahKhan,UniversityofBirmingham

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 16

Graphene oxide is a promising material for water purification with its antimicrobial properties and high sorbing capacity for heavy metals. The in vitro toxicity profile of graphene oxide precludes its direct use in water treatment, but the combination of graphene oxide (and related nanomaterials) with polymers retains the metal adsorbent and antimicrobial properties, with the mitigation of possible toxic side effects. The advancement of nanotechnology has led to theemergenceofvarioustypesofmetallicandcarbon‐basednanomaterials 1,2 .Forexample,grapheneoxide GO ,a carbon‐basednanomaterial, is a promising adsorbentforheavymetals 3‐6 .GOcanadsorbsigni icantlymoreheavymetals Cu2 ,Cd2 ,Co2 fromaqueoussolutionsthanunmodi iedcarbonnanotubesandactivatedcarbon5, 7 . Heavymetal sequestration byGO occursmainlythrough oxygen‐containing functional groups, such ascarboxyl COOH and hydroxyl OH . The removal ofheavy metals is highly dependent on the pH becausethese functional groups can undergo protonation ordeprotonation,dependingonthe pH 4,8 .GOhasanti‐microbialproperties 9,10 ,whichmakesita potentially useful material for water treatment.Concentrations as low as 45mg/L to 85mg/L lead tolevelsofmicrobial inactivationbetween59%and74%,while higher concentrations result in 100% microbialinactivation 10,11 . Although GO has superior anti‐microbial properties and better heavy metal removalcapacity than most commonly used drinking wateradsorbents,invitrotoxicitytestscurrentlyprecludetheuse of GO in water treatment. Several cytotoxicitystudies with GO nanomaterials report problematiceffects on human and other mammalian cells. As

observed in antimicrobial studies, nanomaterial size,shape, dose, and exposure timewere found to play animportant role in their cytotoxic properties. In humancelllines,GOcangeneratereactiveoxygenspecies ROS12 and, depending on the human cell line, thesenanomaterials can be toxic at concentrations varyingfrom 50 mg/L 13 to 85 mg/L 10 . However, whenthese nanomaterials are combined with biologicallycompatible polymers e.g. PEGylation , they exhibitnegligibleinvitrotoxicitytomanycelllines,evenathighconcentrationsupto100mg/L 14,15 .Similarresultswereobservedinanimalmodels 13,15 .Furthermore,itwas found that small sizesofGO‐PEG in the rangeof10 to 50 nm showed no obvious toxic side effects ontreatedmicein40days 16 .Infact,itwasobservedthatthe nanomaterials were gradually excreted by micewhile causing no noticeable toxicity to the treatedanimals 17 .

Overcoming toxicological effects All previous studies showing toxicity of GOnanomaterials were carried out under pristineconditions.Recently,myresearchgroupdeterminedthetoxicity of a nanocomposite containing 30mg/L of GO

Article

Overcoming nanoecotoxicological ef-fects for sustainable remediation of nanomaterials Debora F. Rodrigues (University of Houston, dfrigirodrigues@uh.edu)

Figure1.Logbacterialremovalafter iltrationthroughnanocompositemembrane ilter.Concentrationofnanomaterialsolutionon ilter:1mg/mL.

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 17

embeddedinabiologicallycompatiblepolymer,poly N‐vinyl carbazole PVK , at a concentration of 970 mg/L18 . In this study,we showed that this nanocompositeachieved80%more inactivationofE. coli thanpureGObyincreasingthedispersibilityofGOinaqueoussolution18 .Theseresultsindicatedthatitispossibletoreducethe concentration of GO to levels that are non‐toxic tohumansandanimalsandat thesametimemaintain theantimicrobialpropertiesofGO.Ina further step, todetermine thepotential applicationofthisnanocompositeforwatertreatmentpurposes,myresearchgroupcoatedcommerciallyavailablemembraneilterswithpoly N‐vinylcarbazole PVK ,graphene G ,graphene oxide GO , poly N‐vinylcarbazole –graphenePVK‐G , and poly N‐vinylcarbazole –graphene oxidePVK‐GO .The results demonstrated that graphene‐basednanocomposite membrane ilters had improvedantibacterial activity and heavymetal removal capacitycomparedtounmodi iedmembrane ilters.Toestimatetheeffectivenessofthemodi iedmembraneilters to remove bacteria, bacterial plate counts wereconducted in the iltrate, after iltration of bacterialsolutions.TheresultsdepictedinFigure1showthatbothGO and PVK‐GO plate counts estimated 4 to 3 logremoval for B. subtilis and E. coli, respectively. Theamount of Pb2 removed with the ilter was alsodetermined in the iltrate through atomic adsorptionspectroscopy and reported as percentage Pb2 removalFigure 2 . The results show that the PVK‐GOmodi iedmembrane ilter consistently exhibited the highestpercentage Pb2 removal,with 81.04%, followed byGOmodi iedmembrane ilters,with76.19%Pb2 removal.

Theothermodi iedmembrane ilters, suchasPVK‐G,G,and PVK, could remove 65.51%, 34.21% and 15.53%,respectively.

Conclusion The dispersion of graphene–based nanomaterials inconcentrations that are non‐toxic to humans on thesurface of commercially availablemembrane ilters cansigni icantly improve the antibacterial property andheavymetal removalcapacityofcommercialmembraneilters. Therefore, it is possible to immobilisenanomaterials in nanocomposite forms for applicationsinwatertreatment.

Acknowledgements This project was supported by the National ScienceFoundation Career Award NSF Award #104093 . TheauthorwouldalsoliketoacknowledgeDrYvonneMusicoandDrCatherineSantos.

References 1. J.Warshaw,Dose–Response10 3 ,384 2012 .2. K.Arivalagan,S.Ravichandran,K.Rangasamy,E.

Karthikeyan,Int.J.ChemTechRes.3 2 ,534 2011 .3. X.Wang,Y.Guo,L.Yang,J.Zhao,X.Cheng,J.Environ.

Anal.Toxicol.2 7 2012 .4. Y.L.F.Musico,C.M.Santos,M.L.P.Dalida,D.F.

Rodrigues,J.Mat.Chem.A1 11 ,3789 2013 .5. G.Zhao,J.Li,X.Ren,C.Chen,X.Wang,Environ.Sci.

Technol.45 24 ,10454 2011 .6. G.Zhaoetal.,DaltonTrans.40 41 ,10945 2011 .7. S.Wang,H.Sun,H.M.Ang,M.O.Tadé,Chem.Eng.J.

226,336 2013 .8. C.J.Madadrangetal.,ACSAppl.Mater.Interfaces4

3 ,1186 2012 .9. O.Akhavan,E.Ghaderi,ACSNano4 10 ,5731

2010 .10.W.B.Huetal.,ACSNano4 7 ,4317 2010 .11.Q.Bao,D.Zhang,P.Qi,J.ColloidInterfaceSci.360 2 ,

463 2011 .12.Y.B.Zhangetal.,ACSNano4 6 ,3181 2010 .13.K.Wangetal.,NanoscaleRes.Lett.6,1 2011 .14.Z.Liu,J.T.Robinson,X.M.Sun,H.J.Dai,J.Amer.

Chem.Soc.130 33 ,10876 2008 .15.X.M.Sunetal.,NanoRes.1 3 ,203 2008 .16.K.Yangetal.,NanoLett.10 9 ,3318 2010 .17.K.Yangetal.,ACSNano5 1 ,516 2011 .18.C.M.Santosetal.,Chem.Commun.47,8892 2011 .

Figure 2. Percentage Pb2 removal after passingthrough ilters. Concentration of nanomaterialsolutionon ilter:1mg/mL.

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 18

The need to manage the use of chemicals in a sustainable manner has led to the development of scientific and regulatory approaches for assessing prospective and retrospective risk. As an emerging area of industrial development that can have potential environmental impact, nanotechnology requires similar regulation. With the growing production of a wide array of nanomaterials with different sizes, compositions, surface coatings and other properties, there is concern that some of these nanomaterials may be toxic in ways that are not predictable based on bulk material properties. An initial challenge for the regulation of nanotechnology products is to assess which components of the current chemical risk assessment methods should be used with nanomaterials. Reliable methods are needed for studying how different nanomaterials may behave in natural systems and how they interact with living organisms. Asitgrows,the ieldofnano‐ecotoxicologyhasbeenabletodrawextensivelyonexistingtoolsandtechniquesforassessingchemicalrisk.Withinregulatoryecotoxicology,a key recognised requirement is to have standardisedprotocols available for toxicity testing. Such agreedprotocols are vital because they ensure that studiesconductedindifferentlaboratoriescanbecomparedandcaninformriskassessmentsfornanomaterialregulationunderdifferent jurisdictions.Standardisedtoxicitytests

have also been developed to inform nanomaterialregulation. However, these standard test methods areoften also used in more fundamental nanotoxicologyresearch. Often these uses are entirely appropriate forthe question under study. However, in other cases,limiting studies to standard species, test methods, andendpointsmayleadresearcherstomisskeyaspectsandissues ineco‐nanotoxicology thatwouldberevealedbythe use of nonstandard test systems. For example, agrowingnumberofstudieshaveassessedtheresponsesof soil‐dwelling species to nanomaterial exposure,recognisingthatsoilsarelikelysinksfornanomaterials.Thesestudiesillustratetheimportanceofgoingbeyonda standard set of species, soils, and endpoints tounderstandthetoxicityeffectsofnanomaterials.

Selection of species for testing Toxicity can rarely be examined for a wide range ofspecies or at the ecosystem scale, except for thechemicalsofhighestenvironmentalconcern.Toprotect

Article

Are standard ecotoxicological bioassays a blessing or a curse? David Spurgeon (Centre for Ecology and Hydrology, dasp@ceh.ac.uk)

Credit:kwanchai.c/Shutterstock

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 19

ecosystem structure and function, risk assessmentgenerally relies on data for a very limited number ofusually short‐lived species. To assess nanomaterialtoxicity for soil ecosystems, the most commonly usedtest species are the earthworm Eisenia fetida, thespringtail Folsomia candida and the nematodeCaenorhabditis elegans 1, 2, 3 . Standardised tests forthesespecieshavebeenavailable forover10yearsandarewidely used in nano‐ecotoxicology research. Of the79 papers published on nanomaterial toxicity to soilorganisms by June 2015, 64% studied just these threespecies E.fetida,28%;F.candida,9%;C.elegans,27% .Thesestudieshave led toanumberof insights.At leastfor metal and metal oxide nanomaterials made fromsilver,zincoxideandcopperoxide,nanomaterialtoxicityismostfrequentlylowerthanthetoxicityofthemetalliccomponentaloneinionicform.Indeed,meta‐analysesbyNotter et al. 4 revealed thatnanomaterial toxicity was atorbelowionicmetaltoxicityin93.8%, 100% and 81% ofpairedstudiesforAg,CuOandZnO nanomaterialsrespectively. However, thefocus on so few species limitsthe chance to identifyunexpectedeffectsinspeciesthatarerarely,ifever,usedfor study.Onamorepractical level, focuson justa feworganisms makes it dif icult to develop robust speciessensitivity distributions. For certain metals andpesticides e.g.zinc,chlorpyrifos ,ithasbeenpossibletobuild robust species sensitivity distributions as anexcellent basis from which to derived scienti icallycredible environmental quality standards 5, 6 . Thecurrentfocusonusingmainlystandardtestspeciesmaydelay such comprehensive assessments fornanomaterialsinsoil.

Use of a standard test medium One of the most important innovations to allow thestandardisationof terrestrial toxicity testshasbeen theuseofstandardtestsoils.Natural e.g.LUFA2.2 and/orarti icial soils have been proposed and used for thispurpose.Thedeploymentofthesamemediaacrosstestsprovides a constant set of conditions that governbioavailabilityforthesamesoilindifferentlaboratories.However, the bioavailability and toxicity of metals arestronglyaffectedbydifferentsoilproperties,suchassoilpH,organicmattercontent,claycontent,cationexchangecapacity, and iron oxide content. These soil propertiesmay also affect how nanomaterials behave in soil. Forexample, thechemical compositionof thenanomaterial,pH,organicmattercontentandsoilclaycompositioncan

all affect nanomaterial uptake by organisms and theresultingtoxiceffects 7,8 .Formetals,keyinnovationssuchas theterrestrialbiotic ligandmodel 9 provideamechanistic framework for identifying major soilphysiochemical drivers that in luence nanomaterialtoxicity; knowledge of these drivers can be used tosupport site speci ic risk assessments. To extrapolatenanomaterial toxicity observed in one soil type toanother, there isanurgentneedforthedevelopmentofvariants of these models. Such developments requiredataontoxicity indifferentsoil types,not juststandardtestswithasinglesoiltype.

Measurement endpoints The classic endpoint measured in toxicity tests ismortality.However, thisendpointisacrudemeasureofpossibleecologicaleffect.Inmanystandardtestsforsoilspecies, the capacity also exists to measure sublethal

effects e.g. on reproduction,growth, and even multiple lifecycle traits. Going beyondorganism life cycles, thereremains a dearth of studies ofnanomaterial effects ongenetic/epigenetic,physiological and behaviouralproperties of sensitive soil

organisms. Recent studies on the effects of metal,pharmaceutical and pesticides have shown that thesebiologicaltraitsmaybemuchmoresensitivetochemicalin luencethanaremoreclassicallyassessedendpoints.There is also some evidence that nanomaterials maydifferfromtheirionicchemicalcounterpartsinhowtheyare taken up by organisms. Transcriptomic andbiological imaging studies for soil organisms havesuggested the possibility of active uptake ofnanomaterialsthoughcellularendocytosispathways 10,11 . This uptake mechanism leads to a higher overallaccumulation of nanomaterials than for their metalconstituents. The long‐termphysiological consequencesof this “over‐accumulation” of nanomaterials have notbeen fully established. Itwouldbene it the ield greatlyto understand how these effectsmay underpin impactson sensitive endpoints and the resulting long‐termeffects.Thiswill require tests thatgobeyonddurationsroutinelyusedinstandardtests.

Long-term/transgenerational toxicity Perhaps the greatest challenges for interpreting theeffects of exposure to nanomaterials from currentstandardised toxicity tests is the relatively short‐termnature of these assays. Formany aquatic toxicity tests,the period of exposure is very short 48 or 96 hours .

Because standard tests encour-age the use of a very limited

number of species, many spe-cies and indeed whole phyla will

rarely, if ever, be tested.

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 20

Forsoiltoxicitytests,exposureperiodsareoftenlongere.g.28days .However,consideringthatanearthwormmay be able to survive for up to 5 years, this is arelatively short exposure given the organism’s lifespan.Furthermore, chemical and nanomaterial interactionswith the different components of the epigenome mayaffect to what extent toxic effects are transferred tosubsequent unexposed generations 12 . Further, arecent study conducted in our laboratory with thenematode C. elegans has shown that long‐term multi‐generational exposure results sensitises subsequentgenerationstosilvernanoparticles andalsosilverions ,andthatthissensitisationisretainedevenifexposureisremovedfor ivegenerations.Thus,althoughshort‐termtests may be ideal for identifying acute toxicity, newapproacheswillbeneededtounderstandcomplex,long‐termeffects.

Outlook Given the expected increase in nanotechnologyproductuse, we will become more reliant than ever on theavailability of robust risk assessment scheme to helpbalancerisksandbene itsofthesenovelmaterials.Workconducted to date has shown that key methods forchemical fate modelling, toxicity testing, and biologicalendpoint assessment are often it for purpose forapplications in regulatory nanomaterial assessments.Existingstandardisedtoxicitytestsprovidetractableanduseable tools for the rapid generation of initial toxicitydata that are comparable between laboratories, withonly a few modi ications needed for their use withnanomaterials. Although valuable for routine studies,standardtestsare,however,notapanaceaforallcases.Because standard tests encourage the use of a verylimited number of species, many species, and indeedwholephyla,willrarelyifeverbetested.Thisraisesthereal possibility that vulnerable species are, and willcontinue,tobemissed.Further,itisdif iculttoknowjusthow relevant short‐term data in a single standard testmedium are for different environments, over extendedexposure times, and for all species in exposedcommunities.When considering the use of standard tests for nano‐ecotoxicology, the words of Sumpter and Johnson 13 on the lesson learned from studies of endocrinedisruptingchemicals in theaquaticenvironmentshouldbeborneinmind.Theyconcluded:“Onelesson...duringthe10yearsofresearchonendocrinedisruptionisthatthecurrenttestingregimeusedtodeterminethetoxicityof a chemical to aquatic organisms has “failed”, in thesense that it has not detected the endocrine activity ofmany chemicals” and that “even more surprisingly, ittranspired that EE2 ethinyl estradiol, a potent

endocrine disrupting chemical is acutely toxic to ish,but this effect is delayed long enough that it is notdetected in the acute toxicity test protocols usedcurrently.” These comments suggest that we should becarefulasscientistsnot tooverlyrelyonstandard testsfor ecologically meaningful risk assessment ofnanomaterialsreleasedintotheenvironment.

References 1. OECD,Guidelinesforthetestingofchemicals.No.207

Earthwormacutetoxicitytests OECD,Paris,France,1984 .

2. InternationalOrganizationforStandardization,Soilquality‐InhibitionofreproductionofcollembolaFolsomiacandida bysoilpollutants ISO,Geneva,1999 .

3. ASTM,StandardGuideforConductingLaboratorySoilToxicityTestswiththeNematodeCaenorhabditiselegans ASTMInternational,Conshohocken,USA,2014 .

4. D.Notter,D.M.Mitrano,B.Nowack,EnvironmentalToxicologyandChemistry33,2733 2014 .

5. G.K.Frampton,S.Jansch,J.J.ScottFordsmand,J.Rombke,P.J.VandenBrink,EnvironmentalToxicologyandChemistry25,2480 2006 .

6. P.A.VanSprang,F.A.M.Verdonck,F.VanAssche,L.Regoli,K.A.C.DeSchamphelaere,ScienceoftheTotalEnvironment407,5373 2009 .

7. L.R.Heggelund,M.Diez‐Ortiz,S.Lofts,E.Lahive,K.Jurkschat,J.Wojnarowicz,N.Cedergreen,D.Spurgeon,C.Svendsen,Nanotoxicology8,5592014 .

8. L.Settimio,M.J.McLaughlin,J.K.Kirby,K.A.Langdon,L.Janik,S.Smith,EnvironmentalPollution199,174 2015 .

9. A.Peters,GrahamMerrington,Bioticligandmodels,metalbioavailabilityandregulatoryapplication,ECGEnvironmentalBriefXI,ECGBulletin,January2016,pp.23‐24 2016 .

10.O.V.Tsyusko,J.M.Unrine,D.Spurgeon,E.Blalock,D.Starnes,M.Tseng,G.Joice,P.M.Bertsch,EnvironmentalScience&Technology46,41152012 .

11.M.Novo,E.Lahive,M.Diez‐Ortiz,M.Matzke,A.J.Morgan,D.J.Spurgeon,C.Svendsen,P.Kille,EnvironmentalPollution,205,385 2015 .

12.C.Voelker,C.Boedicker,C.,Daubenthaler,J.,Oetken,M.&Oehlmann,J. 2013 ComparativeToxicityAssessmentofNanosilveronThreeDaphniaSpeciesinAcute,ChronicandMulti‐GenerationExperiments.PlosOne8,e75026 2013 .

13.J.P.Sumpter,A.C.Johnson,EnvironmentalScience&Technology39,4321 2005 .

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 21

Thermal infrared (TIR, 200 to 2000 cm-1) sensors on satellites provide global and diurnal measurements of the Earth’s top-of-the-atmosphere (TOA) radiation. These sensors are most sensitive to the mid- and upper tropospheric regions of the atmosphere, where monitoring of greenhouse gases and pollution plumes has become increasingly important. This Brief describes how thermal infrared radiation can be used to determine atmospheric concentrations from space. ThespectraldistributionofEarth’s thermal radiation isgovernedbyPlanck’s law,whichdescribesthe intensityof radiation, B λ,T , emitted by a black body a perfectabsorber and emitter of radiation in thermalequilibrium as a function of wavelength λ andtemperature T . For a given temperature, the peakintensityofradiationforeachPlanckfunctionisrelatedtoaparticularwavenumber colouredlinesinFigure1 1 . In reality, different types of surfaces, such as land,ocean, and snow, do not emit and absorb radiationef iciently: they are not perfect black bodies. Thisproperty isdescribedby the emissivity ε , the ratiooftheradiationemittedbyanobjecttotheradiationthatitwould emit if it were a perfect emitter/absorber. Atypical Earth spectrum, with a particular surfacetemperatureandemissivity,observed fromaTIRspacesensorwouldthereforelookliketheblacklineinFigure1. This spectrum is not smooth like the Planck curves,but rather exhibits a series of absorption lines andfeatures. These lines contain the spectral ingerprint ofmanymolecular species in the atmosphere. The regionfrom 800 cm‐1 to 1000 cm‐1 is often called the“atmospheric window”, where the atmosphere appearstransparent.ThisregioncanbeusedtogaininformationontheEarth’ssurface,cloudsandaerosols 2 .Figure 2 shows how different atmospheric speciescontribute to the radiation intensity observed in a TIR

spectrum.Somespeciessuchasozone O3 andmethaneCH4 have strong spectral bands. Other species likecarbon dioxide CO2 and water vapour H2O have abroaderseriesofspectrallines or“continuum”spectra presentthroughoutmostoftheTIRspectralregion.The intensity of TIR radiation and the type of featureobserved in aTIR spectrum is dictatedby a number ofprocesses. Firstly, absorption or emission spectrallinesareonlyproducedwhenaphoton isabsorbed oremitted , creating a transition of energy states on amolecular level 3, 4 . In the TIR region, such spectrallinescorrespondtoparticularmoleculartransitionsthataredescribedas rotational,vibrationalor simultaneousrotational‐vibrational 5 .Secondly,photonscanonlybeabsorbedtoproducevibrationalorrotationaltransitionsifthechargearoundthemoleculesisseparatedsoastoproduceapermanentelectricdipole.Thus,thegeometryofthemoleculesandtheabundanceofthespeciesintheatmosphereaffectthetypeofspectralfeatureobserved.NowthatwerecognisewhataTIRspectrum looks like,how canwe relate interactions betweenmolecules andTIRradiationtotheradiationdetectedbyaspace‐bornesensor?

Radiative transfer Imagine a beam of radiation travelling through a smallsection of air. The air is made up of changing

ECG Environmental Briefs (ECGEB No 10)

Thermal infrared remote sensing of the

atmosphere Harjinder Sembhi (University of Leicester, hs32@leicester.ac.uk

Figure1.IntensityofthePlanckradiationspectrum,Bλ,T ,forarangeofterrestrialtemperatures colouredlines andasimulationofatypicalatmosphericspec‐

trum blackline .InPlanck’slaw topright ,κisBoltz‐mann’sconstant,hthePlanck’sconstant,andcthespeedoflight.

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 22

concentrations of different species, with all moleculesabsorbing and emitting thermal radiation at differentrates.Astheradiationtravelsthroughdifferentlayersoftheatmosphere,theintensityofradiationwillconstantlybemodi iedbybothabsorptionandemissionprocesses,asgivenby I Iabsorption Iemissionwhere I isanetchange inradiation.Thisequationisasimpli ication of the Schwarzschild’s Equation, whichtellsushowradiationchangesthroughitstravelledpathdue to all of simultaneous absorption and emissionprocesses.NowimaginethatthisradiationisdetectedbyaTIRsensor,suchasaFourierTransformSpectrometer6 , lookingdownat theEarthalongaparticular lineofsight.Thenetradiationmeasuredbythesatellitesensorwouldbethatwhichisattenuatedthrougheachlayer assmall increments of absorption and emission from thesurface to the top of the atmosphere plus the radiationemitted directly from the surface. In this case, thisprocess can be described by the radiative transferequation RTE : I sensor I surface I atmosphere In remotesensing, I isusuallycalled theradiance withunitsWsr 2m 2 .Theequationisshownhereforaverysimplistic scenario. In reality the atmosphere is highlyscattering aneffectoftenassumedtobenegligibleintheTIR unless clouds and aerosols are present . In thesecases, theRTEbecomesmuchmorecomplextoaccountforadditionalprocessesaffectingtheradiation 1 .

Retrieving atmospheric species Inpractice, informationaboutanatmosphericspecies isretrieved using a computer algorithm to solve theRTE.The algorithms use an inversion technique, i.e. theymathematically invert a TOA satellite radiancemeasurementtoinfertheatmosphericstate.The problem of solving the RTE to determine an

atmospheric concentration is imperfectly de ined,because the satellite measurement only provides asnapshot of information about the atmosphere and wemust make assumptions about the atmospheric andsurface state for that time. There is thus no uniquesolution, and only the most probable solution can bedetermined within some uncertainty range 7 .Generally, for TIR atmospheric retrievals, an optimalestimation OE technique is employed. A typical OEretrieval algorithm requires calibrated spectra from asatellite measurement covering the spectral rangewhich has the largest sensitivity to the target species ;once spectra are extracted, suitable prior data areselected. The prior data are used to simulate with aradiativetransfermodel thesatellitemeasurementandwhen a good simulation is obtained, the algorithmwillsolverelevantequationstoextractthetargetspeciesandanuncertaintyestimate.For theretrieval tobeasaccurateaspossible, thepriordata i.e. vertical pro iles of temperature and pressure,the target species, any interfering species, surfacetemperature and emissivity should match themeasurement time and location as closely as possible.The simulation must incorporate up‐to‐datespectroscopiclineandcrosssectioninformation.Apoorrepresentation of prior data, spectral lines and crosssections will result in an inadequate simulationcompromisingtheaccuracyoftheretrievedquantity.Forspeci ic examples of remote sensing of differenttroposphericspeciesintheEarth’satmospheresee 8 .

References 1.G.W.Petty,AFirstCourse inAtmosphericRadiation,SundogPublishing,Madison,WI,2006.

2.L.Clarriseetal.,Atmos.Chem.Phys.13,2195 2013 .3.B.L.Finlayson‐Pitts,J.N.Pitts,ChemistryoftheUpperand Lower Atmosphere: Theory, Experiments andApplications,AcademicPress,2000.

4.P.F.Bernath,SpectraofAtomsandMolecules,SecondEdition,OxfordUniversityPress,2005.

5. J. M. Wallace, P. V. Hobbs, Atmospheric Science: AnIntroductorySurvey,SecondEdition,Elsevier,2006.

6. P. R. Grif iths, J. A. de Haseth, Fourier TransformInfrared Spectroscopy, Second Edition, Wiley Inter‐Science,2007.

7. C. D. Rodgers, Inverse Methods for AtmosphericSounding:TheoryandPractise,SeriesonAtmospheric,OceanicandPlanetaryPhysics‐Vol2.,WorldScienti ic,2000.

8. J.P.Burrows,U.Platt,P.Borrell,TheRemoteSensingof Tropospheric Composition from Space, Physics ofEarthandSpaceEnvironments,Springer,2011.

Figure2.TIRcontributionofarangeofatmosphericspecies.Thespecieslabelsarecolour‐codedtomatchthespectralfeaturesforeachspecies.

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 23

Biotic ligand models are tools used to predict the trace metal concentration in the water column that will have an adverse effect upon an aquatic organism. This Environmental Brief outlines how biotic ligand models have been developed, and how they are now being applied to set and implement regulatory quality standards. The ecotoxicity of many trace metals to aquaticorganismsdependsonwater chemistry conditions.Thishas been taken into account during the setting ofenvironmental quality standards formetals in the past,predominantlythroughtheuseofwaterhardness‐basedcorrections. These water hardness corrections werebased on the observation that metal toxicity wasgenerallylowerathighhardnessthanatlowhardnessinlaboratory ecotoxicity tests. Regions with soft waterswere identi ied as being particularly sensitive to tracemetal toxicity and so where assigned relatively lowenvironmentalqualitystandards.Fish gills were identi ied as the site of metal uptakecausingtoxicity,andexperimentsledtothedevelopmentof the Gill Site InteractionModel 1 which relates theleveloftoxicitytothedegreeofaccumulationofmetalonthe gill surface. If the binding constant formetal at theishgill isknownthenthedegreeofmetalaccumulationatthegillcanberelateddirectlytothefreeionactivityinthe water that the gill is exposed to. This model alsoresultedinthecalculationofstabilityconstantsformetalbinding to ish gills. The competitive effect of thehardness cations Ca2 andMg2 onmetal toxicity couldthen be interpreted in terms of their competition withdivalent tracemetals binding to ligand sites on the ishgills.Another factor in de ining the toxicity of ametal is thedegree of binding to dissolved organic carbon DOC

suchashumicandfulvicacids,becausethemetal‐organiccomplexes do not contribute directly to the organismtoxicity.Advancesinchemicalspeciationmodellingwereprovided by models, such as the Windermere HumicAqueousModelorWHAM 2 ,whichareabletodescribethe interactions between trace metals and humic andfulvicacids innaturalwaters.Thesemodelsenabledthefree ion activities of metals in natural waters to bepredicted, and where comparisons with directmeasurements of free ion activitieswerepossible therewastypicallygoodagreement 3 .AfurtherkeydevelopmentintheunderstandingoftracemetaltoxicitywasachievedthroughcombiningboththeGill Site Interaction Model with the aqueous speciationmodelWHAMtoproducetheBioticLigandModel BLM 4 . Thismodel treated themetal binding sites presenton the ish gills as an additional ligand in the chemicalspeciationmodel,andenabledtheequilibriumspeciationofmetal between gill ligands, DOC, solution complexes,andthefreeionactivityofthemetaltobepredicted.This

ECG Environmental Briefs (ECGEB No 11)

Biotic ligand models, metal bioavaila-

bility and regulatory application Adam Peters and Graham Merrington (wca environment Ltd,

adam.peters@wca-consulting.com)

Figure1.Schematicofthebioticligandmodel,showingthechemistryspeciationcomponentontheleftandbiologicalinteractionsontheright.Me2 representsadivalentmetalion.POCisparticulateorganiccarbon;DOCisdissolvedorganiccarbon.Adaptedfrom 4 .

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2016 24

development provided the irst direct link between thedissolvedconcentrationofametal,as ismeasureable iniltered samples by routine analyticalmethods, and thelevelof toxicityexperiencedbyanorganism incomplexnaturalwaters.TheBLMconsiderstheinorganicspeciationreactionsofthe metal and system components, and the binding ofcationic species to both DOC usually assumed to bepresentasfulvicacidonly andthe“BioticLigand”,whichisanassumedmetalbindingsiteontheanimalsgills orsomeotherexposedmembranesurface .Thisconceptisshown schematically in Figure 1. The interactionsbetween a tracemetal and cations in the bulk solution,suchasH ,Na ,Ca2 andMg2 ,aremuchmorecomplexthanispredictedbythehardness‐basedmetalstandardshistorically used, because all the cations interactcompetitively at the binding sites on both the DOC insolutionandthebioticligandontheorganism.Therefore,a solution based measurement of either the free ionactivity or some other “available” fraction, is unable tocompletely replicate the sensitivity of the organisms tochangesinthewaterchemistry.

Does the biotic ligand model work? Validation studies have shown that the bioavailabilitymodelswhich have been developed for speci ic speciescanbeappliedtounderstandtheeffectsofbioavailabilityon other species from the same trophic level 5 . Theextrapolation of the BLMs between different speciesrequiresabioavailabilitycorrectiontobemadeforeachindividual species within a species sensitivitydistribution SSD or even each individual toxicityendpointwithinthedatabase tothesamespeci icsetofwater chemistry conditions 6 . This correction allowsthe relative sensitivity of different organisms to becompared under conditions for which they have notnecessarilybeentested.The calculation of a site‐speci ic bioavailabilitynormalisedSSDrequiresawaterqualitystandard,whichmay be derived from data for a particular set of waterchemistryconditions,tobecorrectedforthelocalwaterchemistry conditions at each site. This site‐speci icstandards result in calculated dissolved metalconcentrations against which compliance can beassessedbyroutineregulatorymonitoring,providedthattherequiredsupportingparameterswhichare requiredforthebioavailabilitynormalisationareavailable.WithinEurope,thedevelopmentofbioavailabilitybasedenvironmentalqualitystandardsformetalshasfollowedthistypeofapproach,usinganSSDofchronicecotoxicitydata which is normalised to different water chemistryconditionsusingasuiteofBLMsdevelopedfordifferent

trophic levels. The BLM normalised SSD is thencalculated for a diverse range of European waterchemistriesinordertoidentifythemostsensitivewaterchemistryconditionswhicharelikelytobeencountered.The environmental quality standard is expressed as a“bioavailablemetal”concentration,whichensuresahighlevel e.g. 95% of protection in regions with sensitivewaters i.e. where bioavailability is maximised .Exposure monitoring data for dissolved metal can beconvertedintoa“bioavailablemetal”concentrationusingthe BLM for comparison against the environmentalquality standard. This approach allows theenvironmental quality standard to be expressed as asingle value for example across thewhole of Europe ,whilstalsoenablingittobecorrectedtolocalconditionsand ensuring a consistent level of acceptable potentialrisk.In practice, the available regulatorymonitoringdatadonot tend to includemeasurements of dissolved organiccarbon, which are required for the BLM calculations,although pH is commonly measured. This omissionoccurs because water hardness has historically beenrequired in most cases. It is possible to estimate theconcentrations of othermajor ions in solution from theconcentration of calcium or other parameters 7 withsuf icientprecisiontoallowrobustBLMcalculations.Theroutine regulatory use of BLMsmarks a step change inthe way water quality is assessed and delivers a clearevidence‐drivenlinktoenvironmentalprotection.

References 1.R.Playle,Sci.Tot.Env.,1998,219,147‐163.2.E.Tipping,Comp.Geosci.,1994,20,973‐1023.3.E.Unsworth,K.Warnken,H.Zhang,W.Davison,F.Black,J.Buf le,J.Cao,R.Cleven,J.Galceran,P.Gunkel,E.Kalis,D.Kistler,H.vanLeeuwen,M.Martin,S.Noel,Y.Nur,N.Odzak,J.Puy,W.vanRiemsdijk,L.Sigg,E.Temminghoff,M.Tercier‐Waeber,S.Toppwien,R.Town,L.Weng,H.Xue,Environ.Sci.Technol.,2006,40,1942‐1949.

4.D.DiToro,H.Allen,H.Bergman,J.Meyer,P.Paquin,R.Santore,Environ.Toxicol.Chem.,2001,20,2383‐2396.

5.C. Schlekat,E. vanGenderen,K.deSchamphelaere,P.Antunes, E. Rogevich, W. Stubble ield, Sci. Tot. Env.,2010,408,6148‐6157.

6.P.vanSprang,F.Verdonck,F.vanAssche,L.Regoli,K.de Schamphelaere, Sci. Tot. Env., 2009, 407, 5373‐5391.

7. A. Peters, G. Merrington, K. de Schamphelaere, K.Delbeke,Integr.Environ.Assess.Manag.,2011,7,437‐444.