Arsenic distribution in environment and its bioremediation: A review
arsenopyrite (FeAsS), realgar (AsS), and orpiment
wood-preserving properties and is used in the
(As2S3), are the major natural sources of As release in
timber industry in conjunction with Cu and Cr.
ground water (Nordstrom 2002; Wang and Mulligan
Chromated copper arsenate (CCA) and ammonical
2006).
copper arsenate (ACA) in conjunction with 99% of
Arsenic concentration in most igneous rock types
the arsenical wood preservatives (Perker 1981) are
averages at 1.5 mg kg -1 , whereas, in volcanic gases,
the most common wood preservatives used in the
As level is around 5 mg kg -1 (Ure and Berrow 1982;
industry. Also the use of As in colouring agents
Smedley and Kinniburgh 2002). In metamorphic
such as Scheele’s green (CuHAsO 3 ) or Paris green
rocks, As concentration is generally 5 mg kg -1 with
[Cu (AsO )
2 2
Cu(C2H 3 O ) ] (Azcue and Nriagu
2 2
Pelitic rocks exhibiting the highest concentration
1994) adding to the anthropogenic sources of As
of 18 mg Kg -1 (Boyle and Jonasson 1973). Arsenic
contamination.
typically ranges between 5-10 mg kg -1 (Webster 1999)
Arsenic is a natural component of Pb, Zn, Cu,
in sedimentary rocks. The baseline As concentration
and Au ores. Consequently, As contamination of
in soils generally ranges between 5-10 mg kg -1 . Boyle
the atmosphere, soils, sediments, streams, and
and Jonasson (1973) estimated the average baseline
groundwater is possible during mining and/or
As concentration of 7.2 mg kg -1 , whereas, Ure and
smelting processes. As concentration as high as 1,628
Berrow (1982) quoted a higher average value of 11.3
mg L-1 have been reported in the effluent of industrial
mg kg -1 .
discharges from metallurgical industries involved in
Arsenicisgenerallypresentatverylowconcentration
smelting operations for mining metals (Basha et al. ,
in natural waters. However, Smedley et al. , (1996)
2008). The smelting operations of Cu, Ni, Pb, and Zn
reported As concentration in the range of 100 – 5,000
have emitted 62, 000 tons of As with 80% generated
μg L-1 in unpolluted fresh waters located in areas of
alone through copper smelters (Bissen and Frimmel
sulfide mineralization and mining.
2003). Sadler et al. , (1994) reported As level in soil
near a lead smelter was 0.2 g Kg -1 , whereas, near a
Anthropogenic Sources
copper smelter, the concentration was 0.55 g Kg -1 .
Unlike many heavy metals such as Cr, Cd and Hg
Arsenic is also introduced into the environment
As has been detected in groundwater especially at
through various anthropogenic activities originated
sites contaminated by mill tailings. Bernard (1983)
from primary and secondary industries. Nriagu and
investigated the contamination of groundwater
Pacyna (1988) estimated that the total worldwide
and the subsequent contamination of Lake Moira,
anthropogenic As discharge onto land is 64,000-
Canada, and found that haphazard disposal of mill
132,000 t year-1. They estimated the major sources
tailingsandotherslagwastesresultedinconsiderable
of As discharged onto land were originated from
leaching of As from these sites.
commercial wastes (about 40%), coal ash (about
22%), and atmospheric fallout from the production
As concentration in coal varies from 2 to 82 mg As
of steel (about 13%). Other anthropogenic sources of
kg -1 , depending on geological origin (Adriano et
pollution associated with the mining industry (about
al. , 1980. However, very high concentrations of As
16%) also greatly contributed to As emissions onto
(1500 mg As kg -1 ) have been recorded in brown coal
land.
from the former Czechoslovakia (Bencko and Symon
1977). The volatilization of As hexoxide (As 4 O 6 )
Industrial uses of As include the manufacture of
during coal combustion leads to the emission of As
ceramics and glass, electronics, pigments, antifouling
in the environment which eventually condenses in
agents, cosmetics, and fireworks (Leonard 1991).
the flue system (Bhumbla 1994). Fly ash from the
As trioxide (As 2 O 3 ) is the major form of As that is
thermal power plants may also contribute to As
produced from various industries. As has excellent
contamination of the soil.
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