Occurrence and distribution of heavy metals in the tissues of Physa acuta (D.) in relation to the contamination level of sediments from Boumerzoug wadi (Algeria)

Abstract

The aim of this study was to assess the metallic contamination of sediments, and metals bioaccessibility via their distribution in the gastropod Physa acuta (Pulmonata). The concentrations of Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn in the soft tissue and shell of P. acuta, as well as in fresh surface sediments from the Boumerzoug wadi and its tributaries, northeastern Algeria, were determined by flame atomic absorption spectrophotometry. The samples were collected from ten sites on five occasions (May, September and December 2016, March and July 2017). Results showed that the trace metal mean concentrations in sediments, tissues and shells of the gasteropod, followed a decreasing order: Mn > Zn > Cr > Cu > Ni > Pb > Co > Cd. The pseudo-total contents of Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn in sediment were about 0.45 ± 0.43, 12.19 ± 2.49, 51.70 ± 19.82, 46.70 ± 39.60, 296.15 ± 105.83, 36.50 ± 10.93, 32.40 ± 9.10, and 186.72 ± 118.93 mg/kg dw, respectively. The concentrations of the metals studied in P. acuta were age dependent, with adults having significantly higher concentrations than juveniles. All heavy metal concentrations detected were higher in soft tissue with the lowest coefficient of variation than in shells for both adults and juveniles. The presence of a significant direct relationship between the Cd content in the sediment and in the soft tissues of P. acuta in both adults (r = 0.83; P < 0.01) and juveniles (r = 0.53; P < 0.01), and the high bioaccumulation factor observed make this gastropod a good indicator for the monitoring of freshwater sediment contamination by this metal.