Bioaccumulation of Heavy Metals in Soil Invertebrates: Part 2: Uptake and Accumulation of Lead and Chromium by Achatina marginata (Linnaeus) and Lymnaea stagnalis (Linnaeus)

Abstract

The non-steady state kinetics of lead and chromium in two snails Lymnaea stagnalis and Achatina marginata were examined. The rates of elimination of Pb and Cr were greater in the gut tissues than in the foot mantles of these snails for different levels of contamination. The rates decreased with increase in metal levels in the guts of A. marginata. The studies showed that the snails L. stagnalis and A. marginata eliminated Cr faster than Pb. Moreover, the gut and the foot mantle of L. stagnalis and the foot mantle of A. marginata eliminated Cr faster with increase in metal concentration in the tissues. However, A. marginata eliminated Cr faster than L. stagnalis in both tissues. The elimination of Cr and Pb in both species followed the simple first – order kinetics. The values of rates of elimination calculated were also in agreement with the terminal elimination rate constants. On the basis of elimination factors, the gut tissues of A. marginata gave low elimination factors, implying that these tissues in this species accumulated these metals rapidly. L. stagnalis and A. marginata have low to moderate elimination factors, an indication that these snails might not be suitable for use as bioremediation agents. These snails might however, be used to indicate the presence of lead and chromium in the terrestrial environment.

KEY WORDS: L. stagnalis; A. marginata; Lead; Chromium; Biokinetics.

Global Journal of Environmental Sciences Vol.3(1&2) 2004: 13-19