D. Panda et al., GEOCHEMICAL FRACTIONATION OF HEAVY-METALS IN CHILKA LAKE (EAST-COAST OF INDIA) - A TROPICAL COASTAL LAGOON, Environmental geology, 26(4), 1995, pp. 199-210
Citations number
58
Categorie Soggetti
Water Resources","Environmental Sciences","Geosciences, Interdisciplinary
Chilka lake, the largest coastal lagoon of Asia is one of the most dyn
amic ecosystems along the Indian coast. Historically the lagoon has un
dergone a considerable reduction in surface area due, in part, to inpu
t from natural processes but mostly due to human activities. The purpo
se of this investigation is to document the heavy metals' affinity for
specific geochemical phases in the recently deposited sediments in th
e lagoon. Thirty-three samples were collected and analyzed for differe
nt geochemical phases of Fe, Mn, Cu, Cr, Ni, Pb, and Zn utilizing a se
quential extraction scheme. In the nonlithogenous fraction, the exchan
geable fraction was not geochemically significant, having <2% of the t
otal metal concentration for all the elements. However, the carbonate
fraction contained the following percentages of the total concentratio
n: < 1% Fe, 13% Mn, 6% Cu, 4% Cr, 8% Ni, 13% Pb, and 12% Zn, suggestin
g the detrital origin of the sediments. Reducible and organic matter-b
ound fractions were the significant phases in the nonlithogenous fract
ion, containing 9% Fe, 16% Mn, 15% Cu, 16% Cr, 16% Ni, 14% Pb, and 14%
Zn in the former and 4% Fe, 3% Mn, 17% Cu, 3% Cr, 14% Ni, 15% Pb, and
14% Zn in the latter. The phenomenon has been attributed to the scave
nging affinity of Fe-Mn oxides and affinity for sorption into organic
matter of the lagoon sediments. The lithogenous, residual fraction gen
erally considered as a guide for natural background values was determi
ned to contain 87% Fe, 67% Mn, 61% Cu, 77% Cr, 61.3% Ni, 56% Pb, and 6
0% Zn of the total concentrations.