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ARSENICVery common in most geological environments, igneous,
metamorphic and sedimentary, causing a high background in many parts of north America
Chalcophile, oxyanionic or metalloid element often associated with sulphide ores
Crustal abundance: 1.8 ppm, ranging from 0.1 to several hundred ppm.
Major source of anthropogenic arsenic mobilization is weathering of mine waste rock and tailings as gold is often associated with arsenopyrite especially in Canada
Also common in reduced environment of coal deposits
Orpiment
Realgar
Arsenopyrite
Arsenic contamination
WHO recommended maximum in drinking water 10μg/lEU and US EPA recommended level is 50 μg/l, which is the
level detectable by ICP OES.Up to 5000 μg/l in contaminated water
Groundwater contaminationArgentina, Bangladesh, Chile, China, Hungary, Nepal, India,
Mexico, Romania, Taiwan, Vietnam, SW USA, Myanmar
Contamination from Geothermal WaterArgentina, Dominica, Chile, France, Japan, Iceland, New Zealand,
Alaska USA
In Mining EffluentsCanada, Ghana, Greece, Italy, Russia, Thailand, USA
Periodic Table of the Elements
As is a Group V element (like N and P) Replaces S in minerals and metabolic systems replaces P in minerals and ATP energy cycle
Arsenic ChemistrySeveral oxidation states:
As-1 in sulphide minerals, As0, metal, only stable in very reduced conditions but can be reduced
to As-3 in the most toxic form of arsine gas (AsH3) As3+ As5+ are common in oxidizing conditions and soluble at all values
of Eh and pH
Oxidation of As3+ to less toxic As5+ is slow so usually both are present in oxidized environments like mine tailings.
Arsenic can be removed from mine water by the addition of a solution containing FeSO4.
Fe2+ is oxidized to Fe3+ and precipitates as FEOOHArsenate is strongly absorbed by FeOOH and precipitated
Toxicity of Arsenic Historically arsenic trioxide was known as “inheritance dust”In 55 AD Nero poisoned Britannicus with arsenic to secure the Roman throne 15th/16th centuries, the Italian Borgias used arsenic for political assassinations. Napoleon may have been poisoned by arsenic-tainted wine or by the wallpaper
AsO4-3 replaces PO4
-3 and cells die
AsO4-3 inhibits oxidative phosphorylation in the ATP energy cycle
AsO3-3 replaces S in thiol groups and inhibits protein functions
Absorbed by inhalation or digestion and transferred via the bloodstream to all organs producing systemic damage.
Long term low level exposure causes hyper pigmentation (black spots on skin), followed by skin malignancy, peripheral arteriosclerosis (black foot disease)
Lung, liver and kidney cancer develop over time.
Acute arsenic exposure results in vomiting, abdominal pain and bloody diarrhea and death.
Killer Wallpaper As was used in 1800s as paint, wallpaper and fabric pigments including:
Scheele’s green (copper arsenite), Emerald green (copper acetoarsenite) arsenical Naples ’s yellow, white arsenic trioxide.
By 1863, 700 ton of arsenic green had been manufactured in Britain.
Mass poisoning of Victorian’s, initially attributed to green dust detached from the wallpaper being inhaled.
Around 1900, fungi living on wallpaper paste were found to convert inorganic arsenic into a toxic gas trimethylarsine. This gas had killed many children in their green decorated bedrooms.
William Morris (1834 –1996) produced beautiful papers from hand printed, hand carved blocks from 1864 onwards.
1871. The British Medical Journal: “In the majority of dwelling houses, from palace down to the navy’s hut, it is rare to meet with a house where arsenic is not visible on the walls”. Often there were multiple layers of green wallpaper.
William Morris paper a red rose (Hg) on a green branch (As-Cu).
William Morris (1834–1896) and Mining
William Morris was a utopian idealist, member of the green movement and spoke against the environmental and human degradation caused by industrial activity.
His mining company Devon Great Consols (DGC) was the largest producer of arsenic in the world.
He used his income from DCG to finance his wallpaper design company.
From 1867, DGC was the major supplier of arsenic for the production of Scheele's green for wallpaper
Arsenic pigments were also used extensively in paints and to dye clothes, paper, cardboard, food, soap, and artificial and dried flowers.
Mine workers suffered widely from skin lesions known as arsenic 'pock', and many died from arsenic-related lung disease.
The vast environmental pollution caused by DGC persists
Domestic use of arsenicClothes were coloured with arsenic dyes.
1848 fashion plate: The dress is dyed with arsenic green and the ink used on the print green is a copper-arsenic salt.
Eating arsenic produced a rosy complexion and enhanced “beauty”
Arsenic eaters became immune to the toxic effects
The “arsenic eaters” of Austria found that arsenic has a tonic effect and have built up a tolerance for it, so that they can ingest each day an amount that would normally be a fatal dose.
Pressure treated lumber used arsenic to kill insects and bacteria until high arsenic was found beneath children’s play structures just a few years ago. Now chromate is used.
Still used as a pesticide
Arsenic as MedicineInorganic arsenic has been used in medicine for over 2500 years.
Fowler solution, 1% potassium arsenite, was widely used for treating psoriasis since 1786.
Donovan's solution, AsI3, and de Valagin's solution, AsCl3, treated rheumatism, arthritis, malaria, trypanosome infections, tuberculosis, and diabetes.
Salvarsan, arsphenamine, was the main treatment for syphilis from 1909 until it was replaced by penicillin in the 1940s.
Arsenic is still used in the treatment of severe parasitic diseases.2004, Switzerland: arsenic trioxide is licensed for patients who have
relapsed after initial therapy for acute promyeloctytic leukaemia.
Oriental medicines can contain arsenicJanuary 24, 2008 Health Canada has issued a safety alert warning
consumers that Yeniujyn, a natural health product sold as a treatment for "involuntary passage of urine diseases," contains high levels of lead and arsenic.
Arsenic in India and Bangladesh
Water from tube wells is contaminated with arsenic.
Surface water is contaminated with pathogenic bacteria causing cholera etc.
The tube wells were put in to provide “safer” water with no pathogens and irrigation water for more intensive agriculture during the “Green Revolution”
People become sick with skin lesions, black skin, and eventually cancer. They are shunned by others who think that the disease is contagious.
Men and children are more affected than women.
Bangladesh about 20% of wells are contaminated and an estimated 80 million people are dependent on those wells for domestic purposes and affected by arsenic poisoning.
Source of Arsenic (Kirk Nordstrom)• As-rich sulphide deposits in the Himalayas erode and
As-rich sediment is continuously deposited in the Ganges Delta.
• Mobilization in the well water.
• Oxidation of As rich pyrite with lowering of water table and oxygenation of ground water. Fe2+ oxidizes to Fe3+ and precipitates as Fe oxyhydroxides scavenging As.
• Dissolution of Fe3+oxyhydroxides with the release of As from the surface in reduced conditions in the aquifer.
• Phosphate, from seawater flooding area, can replace As in absorption sites on Fe oxyhydroxides and in sulphides. As released in aquifer
Solutions to arsenic poisening in BangladeshA period of drinking clean water improves the condition of least affected
people as As does not bioaccumulate unlike heavy metals.
Educate people about cause of illness. This has been done in most areasSwitch to less contaminated wells. This has been shown to be successful
despite prognosis that people would not switch if it involved a longer walk
Dig deeper wells into uncontaminated aquifer. This is proving to be successful in Bangladesh and the deep wells are not becoming contaminated
Treat well water with Fe or Al to precipitate As. This is not very successful as people stop treating after a time
Use surface or rainwater for drinking but chlorinate to prevent disease. This is not successful and may lead to further outbreaks of cholera etc.
Increase nutrition particularly folic acid. There is a relationship between folic acid and the effect of As
Increase Se. There is a relationship between Se deficiency and the effect of the As.
More doctors to evaluate and monitor health. This is happening
Giant Mine Yellowknife
Produced >7 million oz Au from1948 to 1999 from refractory arsenopyrite ore. Au is submicroscopic and not extractable by cyanidation
Extraction process was crushing, grinding flotation and roasting ore
Tailings1948-1951 deposited directly into Yellowknife
Bay close to Townsite community.After 1951 deposited into Bow Lake on Giant
Minesite.Streams carried tailings, and calcined ore
from ponds to Yellowknife Bay
In 1971 clay cored dams were constructed to prevent runoff from tailings
Intake for Yellowknife water in Bay moved up stream of discharge from mine.
Beach at Town site is contaminated with As.Houses (and playground) are being demolished
Legacy of Roasting Ore1949 to 1951 the As2O3 and SO2 went
up the stack and was deposited down wind of the mine
After 1951 As2O3 was collected using in an electrostatic precipitator, (ESP) collected and blown directly underground and stored behind bulkheads in mine out chambers
1958 dust from ESP treated with cyanide to remove Au prior to deposition in tailings ponds
Environmental Issues
Tailings in pondsContaminated beach areaContaminated Streams on
Mine SiteRoaster Ore deposited on
Mine Site
Soluble As2O3 stored underground in chambers that are the equivalent size of seven 11 story office blocks and are leaking
Solutions to Environmental Issues
Tailings pond water being treated with FeSO4 to remove As
Monitoring of ground and surface waterMineralogical and geochemical studies of tailings,
calcined ore, soil, beach deposits and lake sediments by INAC
Solution to 237,000 tonnes As2O3 dust releasing As from
underground chambers
Not possible to remove and bury elsewhere because of expense and danger to community and workers during removal and after reburial.
Solution accepted by community and INAC is to reintroduce permafrost around the chambers using active and passive refrigeration units.
Now there is a new public review called for to determine if this is the correct solution