Résumé:
The worrying environmental situation in Algeria today is the result of the irresponsible use
of non-renewable resources to meet the excessive needs of industry and agriculture over
the past century, several persistent pollutants were released and then accumulated in the
different ecosystems. Trace metal elements are classified as one of the most dangerous
pollutants due to their high toxicity and persistence in the environment. This study was
conducted to assess the state and quality of contaminated soils with metals by the use of
the snail Helix aspersa (syn. Cantareus aspersus or Cornu aspersum O.F. Müller, 1774) as
a bioindicator via ex situ and in situ ecotoxicity tests. Indeed, two ex situ tests were
performed to determine a dose-response relationship between Pb or Cd concentrations in
soils and the growth of weight and shell diameter of H.aspersa species according to the
recommendations of ISO 15952 (2006).In addition, six ex situ tests were conducted to
assess the influence of soil physicochemical parameters on lead and cadmium
bioavailability and toxicity to Helix aspersa. Finally, the soils of two areas with different
levels of metallic contamination in North-East Algeria have been investigated via active
biomonitoring (in situ test); Indeed, sub-adult populations of H. aspersa have been exposed
under natural conditions to soils in two areas: B'kira - Constantine and El Hadjar Ŕ
Annaba. Inhibitory concentrations of 50% of Helix aspersa growth (IC 50) were ranged
between 2397-8194 µg/g for lead and 327-910 µg/g for cadmium. The physicochemical
properties of the soil, including pH, CEC and OM, have a clear effect on the bioavailability
and toxicity of Cd and Pb to Helix apsersa. Total metal concentrations in the soils studied
were ranged from 22.27 to 635.38 µg/g for lead and 0.13 to 0.53 µg/g for cadmium. The
species H. aspersa showed a higher accumulation capacity for Cd than for Pb. This study
confirms the high performance of Helix aspersa in the ecological risk assessment for
contaminated soils with metals.
