Field evaluation of metal bioaccumulation in the gastropod Helix aspersa at agricultural and industrial sites in Lebanon.

Abstract

Juvenile Helix aspersa Müller exposed in field microcosms were used to assess the spatial and temporal bioaccumulation of Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn at two agricultural and two industrial sites in Lebanon. The study was performed over a 12-week period where caged snails were sampled once every 3weeks and assessed for metal bioaccumulation and partitioning between soft tissue and shells. Results showed that metal bioaccumulation by snails was site dependent, with Fe and Cd being the greatest and least accumulated metals, respectively. Significant differences between bioaccumulation in each of the matrices (soft tissue and shells) were also observed. Time-dependent bioaccumulation results showed an increasing accumulation trend at both agricultural sites, while a slight decline was observed at the end of the sampling campaign for the industrial sites. The study of the bioaccumulation factors (BAF) revealed that tested H. aspersa were macroconcentrators for Zn and Cd (BAF > 2) and deconcentrators for all other analyzed elements (BAF < 1). The high partitioning factor values obtained for Cu and Zn indicate an affinity of these two elements for the soft tissues of the snails. The results of this field study indicate that H. aspersa are well suited for active biomonitoring and could provide reliable information on metal pollution and bioavailability.