ATMOSPHERIC DEPOSITION OF NITROGEN AND SULFUR

ATMOSPHERIC DEPOSITION ATMOSPHERIC DEPOSITION OF NITROGEN AND SULFUROF NITROGEN AND SULFUR

Kuliah Kimia LingkunganKuliah Kimia Lingkungan

Program Studi Kimia FMIPA ITBProgram Studi Kimia FMIPA ITB

Keith, L. H., Energy and Environmental Acid Rain Chemistry, Volume 2, Ann Arbor Science Publisher, USA, 1982. Chapter 8, page 123 - 145

Atmospheric precipitationAtmospheric precipitation

Atmospheric precipitation is comprised of:Atmospheric precipitation is comprised of:• Dry componentsDry components: particulate and gases: particulate and gases• Wet componentsWet components: rain, snow, fog: rain, snow, fog

Factors that affects Factors that affects chemical characteristicchemical characteristicof atmospheric precipitate:of atmospheric precipitate:• Ocean saltsOcean salts • Gaseous air pollutants• Gaseous air pollutants• Natural air-borne dust • Rainfall rate, frequency,Natural air-borne dust • Rainfall rate, frequency,• Soil particlesSoil particles and distribution and distribution

Learning ObjectivesLearning Objectives

Develop good understandings about:Develop good understandings about:

• What is What is acid rainacid rain

• How it is How it is formedformed

• What What problemsproblems might arise if acid rain might arise if acid rain occursoccurs

Rain and acidityRain and acidity

• Rain, in its theoretically normal, Rain, in its theoretically normal, unpolluted unpolluted statestate, is , is slightly acidslightly acid, with , with pH 5.6pH 5.6, due to , due to carbonic acid (Hcarbonic acid (H22COCO33) which is a product ) which is a product of the dissolution of atmospheric carbon of the dissolution of atmospheric carbon dioxide (COdioxide (CO22))

• Acid rainAcid rain is defined as rain with a is defined as rain with a pH<5.6pH<5.6

Rain and acidityRain and acidity

• The oxides of sulfur and nitrogen (The oxides of sulfur and nitrogen (SOSOxx and and NONOxx) ) are oxidized in the atmosphere and form sulfuric are oxidized in the atmosphere and form sulfuric and nitric acids (and nitric acids (HH22SOSO44 and and HNOHNO33))

• These acids These acids contribute to rain aciditycontribute to rain acidity

• Sulfur compounds (and maybe also nitrogen Sulfur compounds (and maybe also nitrogen compounds) can be compounds) can be transported several hundred transported several hundred kilometers per daykilometers per day in the atmosphere in the atmosphere

• Chlorine emission may also result in acidity Chlorine emission may also result in acidity (hydrochloric acid (hydrochloric acid HClHCl), but usually only ), but usually only close to close to emission sourcesemission sources

Sources of S and N in atmosphereSources of S and N in atmosphere

• Sulfur oxidesSulfur oxides are primarily emitted from are primarily emitted from stationary sourcesstationary sources, such as utility and , such as utility and industrial coal-burning boilersindustrial coal-burning boilers

• Nitrogen oxidesNitrogen oxides are emitted from both are emitted from both stationary and mobile sourcesstationary and mobile sources, especially , especially automobilesautomobiles

Data from US EPA (1977):Data from US EPA (1977):

• ~56% of ~56% of NONOxx was caused from the was caused from the burning of burning of fossil fuels by stationary sourcesfossil fuels by stationary sources

• 40% came from 40% came from transportation-related sourcestransportation-related sources

Sources of S and N in atmosphereSources of S and N in atmosphere

The combustion of fossil fuel in the US results The combustion of fossil fuel in the US results in in ~50 million metric tons of SO~50 million metric tons of SOxx and NO and NOxx being being emitted to the atmosphere per yearemitted to the atmosphere per year

In 1977:In 1977:

• SOSOxx accounted for 14% ( accounted for 14% (27.4 million 27.4 million metric tonsmetric tons) of the total air pollution) of the total air pollution

• NONOxx accounted for 12% ( accounted for 12% (13 million metric 13 million metric tonstons) of the total air pollution) of the total air pollution

→ → result in acidresult in acid rain, especially in rain, especially in northeastern US and Scandinavianortheastern US and Scandinavia

Ecological effects of acid rainEcological effects of acid rain

• Degradation of Degradation of water qualitywater quality

• Decrease in Decrease in fish productivityfish productivity

• Decrease in Decrease in forest productivityforest productivity

• Accelerated Accelerated soil leachingsoil leaching

Less concern about effect of acid rain is Less concern about effect of acid rain is usually caused by:usually caused by:

• data unavailabilitydata unavailability or or only few data are availableonly few data are available

–about chemical characteristic of precipitationabout chemical characteristic of precipitation

–environmental degradation caused by environmental degradation caused by changes of precipitation chemistrychanges of precipitation chemistry

• emission of emission of SOSOxx and and NONOxx are thought as are thought as only only causing less environmental effectscausing less environmental effects

Ecological effects of acid rainEcological effects of acid rain

Research performedResearch performed

• Objectives: Objectives:

– to to monitor both wet and dry componentsmonitor both wet and dry components of of atmospheric precipitationatmospheric precipitation

– to determine the geographical extent and to determine the geographical extent and temporal temporal variation of acid rainvariation of acid rain in certain in certain regionregion

– to anticipate some to anticipate some possible ecological effectspossible ecological effects of acid rainof acid rain

Research performedResearch performed

• SitesSites to be analyzed? to be analyzed?

• Sampling methodsSampling methods? Time? ? Time?

• Chemical analysisChemical analysis? Methods and ? Methods and pollutants/compounds to be analyzed?pollutants/compounds to be analyzed?

• Ecological analysisEcological analysis? Type of indicators and ? Type of indicators and organism to be investigated?organism to be investigated?

• Statistical methodsStatistical methods? ?

• Possible interpretationPossible interpretation??

The sitesThe sites

• The sites were chosen as a representative of geographical condition, vegetation, and land uses

• The sites includes pollution source-areas, and potential receptor-areas where ecological effects may be important

• The sites represent a small network, each site being close enough for interpretative purposes, e.g. to infer possible atmospheric transport between source sites and receptor sites

SamplingSampling• Separate samples of Separate samples of wet and dry falloutwet and dry fallout were collected were collected

• A A two-bucket systemtwo-bucket system with movable lid were used, with movable lid were used, designed to expose the wet bucket and cover the dry designed to expose the wet bucket and cover the dry bucket during periods of wet precipitation bucket during periods of wet precipitation (and vice versa)(and vice versa)

• A A sensorsensor, mounted on the frame, reacts electrically to , mounted on the frame, reacts electrically to the onset of precipitation that causing the lid to movethe onset of precipitation that causing the lid to move

• This equipment (which has been modified to improved This equipment (which has been modified to improved performances) is now used by the US National performances) is now used by the US National Atmospheric Deposition Program as a Atmospheric Deposition Program as a standard standard sampling systemsampling system

Collector used for monitoring wet and dry Collector used for monitoring wet and dry atmospheric precipitationatmospheric precipitation

Sampling and subsequent chemical analysis were performed Sampling and subsequent chemical analysis were performed after each main storm event at the determined sitesafter each main storm event at the determined sites

Chemical analysisChemical analysis

• pH of each samplespH of each samples were measured in the field were measured in the field with Corning Digital 112 Research meter, with Corning Digital 112 Research meter, calibrated with buffer ph 4 – 7calibrated with buffer ph 4 – 7

• Samples were filteredSamples were filtered through 0.45- through 0.45- Millipore Millipore prior to all analysisprior to all analysis

• Chemical digestion were done with Chemical digestion were done with boiling nitric boiling nitric acidacid and and hydrogen peroxideshydrogen peroxides

• Cations were determined by Cations were determined by atomic absorption atomic absorption spectrophotometryspectrophotometry using Varian Model AA6 using Varian Model AA6

Chemical analysisChemical analysis

• ChlorideChloride was determined using spectrophotometry was determined using spectrophotometry

• SulfateSulfate was determined using barium chlorinated was determined using barium chlorinated spectrophotometric methodspectrophotometric method

• NitrateNitrate was determined by a hydrazine reduction was determined by a hydrazine reduction

• AmmoniumAmmonium was determined by indophenol was determined by indophenol

• All data were analyzed using All data were analyzed using SPSSSPSS package package program (Statistical Programs for Social Sciences)program (Statistical Programs for Social Sciences)

Results and discussionsResults and discussions• Acid rain is commonly occurred, pH = 3.71 – 5.20

• Several region closed to cement factory appeared to have relatively high pH values, pH = 6.40 – 6.73. This region is used as agricultural areas. Possibly due to upwind emission of alkaline particulates from the cement factory.

• One particular site showed wide range of pH (from 3.71 – 6.29), illustrate the necessity for event monitoring (in contrast to weekly or monthly monitoring – for example), to provide data for interpretative purposes

• In some regions, there is a correlation between In some regions, there is a correlation between [H[H++] with [NO] with [NO33──]]

• In one region In one region [SO[SO4422──] > ] > [NO[NO33──]]

• In one other region, there is a correlation In one other region, there is a correlation between [SObetween [SO4422──] and ] and [H[H++], where correlation of ], where correlation of [H[H++] and [NO] and [NO33──] is not significant, suggested the ] is not significant, suggested the occurrence of different acidity sourcesoccurrence of different acidity sources

• Sulfuric acid in rain may be originated from Sulfuric acid in rain may be originated from air air pollution from oil fieldspollution from oil fields upwind, or the use of upwind, or the use of ammonium sulfate fertilizerammonium sulfate fertilizer in agricultural area in agricultural area

Results and discussionsResults and discussions

ResultsResults

A strong correlation ofA strong correlation of [H+] with [NO3─] [H+] with [NO3─] in in one particular regionone particular region

Ionic Ionic concentrations concentrations varied widelyvaried widely between between storms at a storms at a given sitesgiven sites

ResultsResults

• Fluctuation of [HFluctuation of [H++], [SO], [SO4422──], and ], and [NO[NO33──] illustrate ] illustrate that it that it is difficult to generalize the infer effect is difficult to generalize the infer effect from mean data alonefrom mean data alone

• It is also It is also difficult to generalize the relationship difficult to generalize the relationship betweenbetween storm frequency storm frequency oror storm volume storm volume to the to the correspondingcorresponding ionic concentration ionic concentration

• It is some evidence that It is some evidence that pH of rain was higher 20 pH of rain was higher 20 years agoyears ago


• Oceanic saltsOceanic salts are carried out inland and are carried out inland and deposited both as dry and wet deposited both as dry and wet precipitationsprecipitations

• Sites which are closed to ocean, receive Sites which are closed to ocean, receive relatively relatively large amountslarge amounts of both wet and of both wet and dry deposition of dry deposition of NaNa++ and Cl and Cl──

• Total ocean salt deposition is Total ocean salt deposition is dependent dependent upon total rain or snowupon total rain or snow on the site on the site


• These functions are useful tools to predict These functions are useful tools to predict the contribution of other ionic constituents of the contribution of other ionic constituents of rain derived from oceanic sourcesrain derived from oceanic sources

• In oceanic water, In oceanic water, ratio of ratio of [[ClCl──] : [] : [NaNa++] = 1,17] = 1,17

• Using the Using the ClCl─ ─ as a basis, as a basis, andand assuming that assuming that

all [all [ClCl──] is of oceanic origin, ] is of oceanic origin, [[NaNa++] can be ] can be calculated if calculated if [[ClCl──] is known] is known


• Other salts concentration in rain water Other salts concentration in rain water (such as (such as CaCa22++, Mg, Mg22++, SO4, SO422──, etc.) , etc.) originated from oceanic water could also originated from oceanic water could also be predictedbe predicted

• If the concentration of these ions in rain If the concentration of these ions in rain water at any sites water at any sites exceeds that of the exceeds that of the predictedpredicted, than the excess can be , than the excess can be reasonably assumed to be reasonably assumed to be due to sources due to sources other that oceanother that ocean


• Similar calculations of Similar calculations of ion ratios relative to ion ratios relative to specific elementsspecific elements uniquely derived from uniquely derived from known sources also known sources also allow the prediction of allow the prediction of quantities of different elementsquantities of different elements

• SilicaSilica may be a good indicator for soil may be a good indicator for soil derived air and rain pollutantsderived air and rain pollutants

• LeadLead may indicate pollutants from may indicate pollutants from automobile exhaust emissionsautomobile exhaust emissions

• These indicators have been extensively These indicators have been extensively used in used in air pollution studiesair pollution studies, but only very , but only very limited extent for on limited extent for on rain pollution studiesrain pollution studies


• Close attention should be given to Close attention should be given to total total deposition valuesdeposition values as well as as well as concentration concentration valuesvalues to anticipate different types of to anticipate different types of ecological ecological effects. effects. For examples:For examples:

– Plant or fishPlant or fish sensitivity to acidity may be sensitivity to acidity may be determined by determined by threshold pHthreshold pH

– Accelerated Accelerated soil leachingsoil leaching and and rock weatheringrock weathering are more likely to be determined by increases are more likely to be determined by increases in the in the total deposition of acidic materialstotal deposition of acidic materials


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ATMOSPHERIC DEPOSITION OF NITROGEN AND SULFUR