Introduction to arsenic (environmental series)

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

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

Orpiment

Realgar Arsenopyrite

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

15 th /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 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

Still used as a pesticide

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

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

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