Introduction to arsenic (environmental series)

ARSENIC Very 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 Arsenopyrite Orpiment Realgar Arsenic contamination WHO recommended maximum in drinking water 10μg/l EU 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 contamination Argentina, Bangladesh, Chile, China, Hungary, Nepal, India, Mexico, Romania, Taiwan, Vietnam, SW USA, Myanmar Contamination from Geothermal Water Argentina, Dominica, Chile, France, Japan, Iceland, New Zealand, Alaska USA In Mining Effluents Canada, 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 Chemistry Several 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 FEOOH Arsenate 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 William Morris paper a red Mass poisoning of Victorian’s, initially attributed to green dust detached rose (Hg) on a green branch from the wallpaper being inhaled (As-Cu) 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 By 1863, 700 ton of arsenic green had been manufactured in Britain 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 (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 arsenic Clothes 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 Arsenic as Medicine Inorganic 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 arsenic January 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 Bangladesh A 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 areas Switch 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 Tailings 1948-1951 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 Ore 1949 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 ponds Contaminated beach area Contaminated Streams on Mine Site Roaster 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 water Mineralogical 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 [...]... 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 Tailings 1948-1951 deposited directly into Yellowknife Bay close to Townsite community After 1951 deposited into Bow... 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 water Mineralogical 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... 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... 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 ponds Contaminated beach area Contaminated Streams on Mine Site Roaster Ore deposited on Mine Site Soluble As2O3 stored underground in chambers that... oxyhydroxides and in sulphides As released in aquifer Solutions to arsenic poisening in Bangladesh A 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 areas Switch to less contaminated wells This has been shown to be successful despite prognosis that people would not... 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 Ore 1949 to 1951 the As2O3 and SO2 went up the stack and was deposited... 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 ...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 •