Geoscience Reference
In-Depth Information
Inorganic As
O
HO
As
OH
HO
As
OH
OH
OH
Arsenate
Arsenite
Organic As
O
O
CH
3
CH
3
As
+
HO
As
OH
As
OH
As
X
-
CH
3
CH
3
CH
3
CH
3
CH
CH
3
CH
3
CH
3
CH
3
Monomethyl-
arsonic acid
(MMA)
Dimethyl-
arsinic acid
(DMA)
Trimethylarsine
oxide
(TMAO)
Tetramethylarsonium
cation
(TETRA)
O
-
O
CH
3
CH
3
O
As
+
As
+
X
-
CH
3
CH
3
CH
2
OH
CH
3
CH
2
C=O
CH
3
As
OCH
2
CH(OH)CH
2
R
CH
3
Arsenocholine
CH
3
OH OH
Arsenobetaine
Arsenosugar
Figure 3.2. The most common As species found in soil, water, and living organisms (modified from Meharg
and Hartley-Whitaker, 2002); X
=
accompanying anion.
HO
As
CH
3
As
CH
3
CH
3
CH
3
CH
3
Dimethylarsine
(volatile)
Trimethylarsine
(volatile)
O
O
O
HO
As
OH
HO
As
OH
HO
As
OH
CH
3
As
OH
OH
OH
CH
3
CH
3
Arsenate
Arsenite
Monomethyl-
arsonic acid
Dimethyl-
arsinic acid
Figure 3.3.
Transformations of As species in soils (modified from Wood, 1974, and Bhumbla and Keefer,
1994).
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