ARSENIC CONTAMINATION AND ITS RISK MANAGEMENT IN COMPLEX ENVIRONMENTAL SETTINGS
S. Mahimairaja,1,* N. S. Bolan,1 D. C. Adriano2
and B. Robinson3
1lnstitute of Natural Resources, Massey University, Palmerston
North, New Zealand
2Savannah River Ecology Laboratory, The University of Georgia,
Aiken, Soum Carolina 29802
3HortResearch, Palmerston North, New Zealand
Contamination of terrestrial and aquatic ecosystems by arsenic (As) is
a very sensitive environemntal issue due to its adverse impact on human
health. Although not anthropogenic in origin, the problem of As contamination
in groundwatcrs of West Bengal (India) and Bangladesh has been considered
of calamitous proportion because significant segment of the population
is at high risk, with untold numbers aJready suffcring from irreversible
effects of As poisoning. E1scwhere, indiscriminate disposal of industrial
and mining wastes has led to extensive contamination of lands, thereby
cxacerbating tht potential for food chain contamination. With greater
public awarcness of As poisoning in animal and human nutrition, therc
has been a growing intcrest in developing regula.tory guidtlines and remediation
tcchnologits for mitigating As-contaminated ecosystems. Although the immediate
needs revolve around the stripping of As from domestic water supplies
as exemplified by the affected areas in Bangladesh and West Bengal, a
remediation scheme should also be explortd to be able to cope with pivotal
needs to abate the contamination of soils, sediments, and water and the
potential to compromise the quality ofthc food chain. A range of technologies,
including bioremediation, has been applied with varying levels of success
either to remove As from the contaminated medium or to reduce its biotoxicity.
This review provides general overview of the various biogeochemical processes
that regulate As bioa vailability to organisms including microbes; plants,
animals and humans. In turn, the role of the source term, chemical form,
and chemical species of As are discussed as an overture to As bioavailability.
Having laid the fundamental mechanisms and factors regulating As bioavailability,
we then assembled the various physical, chemical, and biological mitigative
methods that have been demonstrated, some being practical, highlighting
their special strengths and potential for more effective and economical
widespread applications. Because of the complexity involved in dealing
with contaminated sites, exacerbated by site characteristics, nature of
hydrogeology, source term, chemical form, land use, and so on, no one
remedial technology might suffice. Therefore, we have attempttd to offer
an "integrated" approach of employing a combination of technologies
at multiscalar levels, depending on extenuating circumstance, with the
aim of securing viable methods, economically and technologically. Future
research needs, especially in the area of As bioavailability and remediation
strategies are identified.
SREL Reprint #2860
Mahimairaja, S., N. S. Bolan, D. C. Adriano and B. Robinson. 2005. Arsenic contamination and its risk management in complex environmental settings. p. 1-82. In Advances in Agronomy, edited by D. L. Sparks. Elsevier/Academic Press. San Diego, CA.
