EMCB-ENVIS Node ENVIRONMENTAL BIOTECHNOLOGY

EMCB-ENVIS Centre
Nontarget Arthropodan Fauna Associated with Subalpine Mosquito Breeding Sites.
Ecotoxicology and Environmental Safety, 52(1) (2002), 8-12.
In order to examine ecological impact of fipronil use for larval culicine control in natural
hydrosystems, toxicity and bioaccumulation of this new insecticide were analyzed on aquatic
species representative of the nontarget arthropodan fauna (nonculicine larval Diptera:
Chaoboridae, Chironomidae; planktonic Crustacea: Cladocera, Copepoda, Ostracoda) associated
with target larval mosquito populations in the subalpine breeding sites. Standard toxicological
bioassays using fipronil aqueous solutions from 1 to 2000 nM indicated different sensitivity
levels among species. Insecticide bioaccumulation analyses, using [ 14 C]fipronil solutions in
simplified laboratory ecosystem, also indicated large differences among species. These
differences may come from biological parameters characteristic of each species. Taking into
account these nontarget effects of fipronil, a possible strategy of use of this insecticide for
integrated mosquito control management was proposed, which is based upon selective dietary
absorption of the insecticide by larval Culicidae.
P. Waranusantigul, P. Pokethitiyook, M. Kruatrachue, E. S. Upatham. (Department of
Biology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand. Mahidol
University International College, Mahidol University, Nakhonpathom 73170, Thailand.
Faculty of Science, Burapha University, Chonburi 20131, Thailand). Kinetics of basic dye
(methylene blue) biosorption by giant duckweed (Spirodela polyrrhiza).
Environmental Pollution, 125(3) (2003), 385-392.
Wastewater containing pigments and/or dyes can cause serious water pollution problems in the
form of reduced light penetration and photosynthesis, and the toxicity from heavy metals
associated with pigments and/or dyes. Laboratory investigations, of the potential use of dried
Spirodela polyrrhiza biomass as an adsorbent for the removal of the basic dye methylene blue
from aqueous solution were conducted. A series of experiments were undertaken in an agitated
batch adsorber to assess the effect of the system variables, i.e. sorbent dosage, pH, and contact
time. The results showed that as the amount of the dried S. polyrrhiza increased, the percentage
of dye sorption increased accordingly. At pH 2.0 the sorption of dye was not favorable, while the
sorption at other pHs (3.0–11.0) was remarkable. There was no significant difference in the dye
concentration remaining when the pH was increased from 3.0 to 11.0. The dye removal time was
influenced by the initial dye concentration, and the process followed the first-order rate kinetics.
The rate constants for intraparticle diffusion were 1.00 and 3.27 mg/g/min 1/2 for 300 and 500
mg/l of dye, respectively.
Piyush Kant Pandey, Sushma Yadav, Sumita Nair, Ashish Bhui. (Department of Engineering
Chemistry, Bhilai Institute of Technology, Bhilai House Durg, CG, Bhilai, MP 491002, India).
Arsenic contamination of the environment- A new perspective from central-east
India. Environment International, 28(4) (2002), 235-245.
This paper reports a regional contamination of the environment in central-east India that does not
share geology or boundary with the Bengal Delta Plain. About 30,000 people residing in 30
villages and towns are directly exposed to arsenic and more than 200,000 people are "at risk."
Complete geographical extent of this contamination is being established, and this newly reported
contaminated area could be quite large. This paper further reports that the mechanisms involved
in arsenic mobilisation are complex and the two theories of arsenic mobilisation, i.e., pyrite
oxidation and oxyhydroxides reduction, do not fully explain the high levels of arsenic
contamination. This paper also proposes the "oxidation–reduction theory" for arsenic
mobilisation where the arsenic originates from the arsenopyrite oxidation and the arsenic thus
mobilised forms the minerals and gets reduced underground in favourable Eh conditions. The
stoppage of water withdrawal from the contaminated sources did not result in lowering of arsenic
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