ARSENIC

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					                           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   As is a Group V element (like N and P)
                         Replaces S in minerals and metabolic system
the Elements             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.

By 1863, 700 ton of arsenic green had been manufactured in Britain.        William Morris
                                                                           paper a red
Mass poisoning of Victorian’s, initially attributed to green dust detached rose (Hg) on a
   from the wallpaper being inhaled.                                       green branch
                                                                           (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.

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.

       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
     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