Herbicides arsenic sources

Concerning anthropogenic sources, methyl arsenic compounds such as methyl arsonic acid and dimethylarsinic acid have been used as herbicides, and were once a significant source of environmental residues. Dimethyl-arsinic acid (Agent Blue) was used as a defoliant during the Vietnam War. 

Arsenic geochemistry in Chesapeake Bay, Maryland, depends on anthropogenic inputs and phytoplankton species composition (Sanders 1985). Inputs of anthropogenic arsenic into Chesapeake Bay are estimated at 100 kg daily, or 39 tons/year — probably from sources such as unreported industrial discharges, use of arsenical herbicides, and from wood preservatives (Sanders 1985). The chemical form of the arsenic in solution varies seasonally and along the axis of the bay. Arsenic is present only as arsenate in winter, but substantial quantities of reduced and methylated forms are present in summer in different areas. The forms and distribution patterns of arsenic... 

Although the predominant source of arsenic and metals to most soils and sediments in New England is sulfide-rich rock, the extensive application of arsenical pesticides and herbicides (lead arsenate, calcium arsenate, and sodium arsenate, and others) on apple, blueberry, and potato fields may have been a possible anthropogenic source of arsenic and lead. The main objective of this study was to determine the lead isotopic compositions of commonly used pesticides, such as lead arsenate, sodium metarsenite, and calcium arsenate, in order to assist in future isotopic comparisons and to better characterize this anthropogenic source of Pb. The pesticides plot along a linear trend in isotope diagrams, for example, in values of... 

Industrial and environmental sources cause most modern cases of arsenic poisoning. A National Institute for Occupational Safety and Health study in 1975 estimated that 1.5 million workers had potential exposure to arsenic (Hartman 1988). Poisonings have resulted from veterinary compounds, paints, herbicides, pesticides, rodenti-cides, treated lumber, and Chinese herbal products (Garvey et al. 2001 Gosselin et al. 1984 Peters et al. 1983). Table 7-1 lists occupations with the greatest risk of exposure to arsenic. 

Arsenic Essential ultratrace element in red algae, chick, rat, pig, goat, and probably bumans. Deficiency results in depressed growth and increased mortality. Moderately toxic to plants, highly toxic to mammals. Serious pollution problems in some areas sources include mining, burning coal, impure sulfuric add, insecticides, and herbicides. 

Stressed vegetation is evident at numerous places throughout the site. Arsenic is a known herbicide, and these areas need further assessment to determine if arsenic is causing the problem. Fish tissue studies from the Potomac River indicate arsenic contamination. Further sampling must be done to assure the District of Columbia that the site is not the source for this arsenic. 

Arsenic trioxid formerly used as a herbicide and currently used as a source for other arsenicals... 

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