Snail watch to survey the transfer of PCB and PCDD/F on a polluted site converted into a photovoltaic power plant

In 2008, a fire on a former industrial site in Saint Cyprien (France) caused a severe contamination with persistent organic pollutants (POP) to surrounding soils. About 14 hectares of pasture were consequently forbidden to agricultural use. To give a new usage to this site, a power plant was built in 2010 by Luxel SAS. This installation produces green electricity since early October 2013 and constitutes a pilot site for research on POP toxicity and degradation processes over time with bioindicators. The objective of the research program TROPE (Transfer and Risk of Organic PErsistent pollutants for snails) was to assess, thanks to active biomonitoring, the bioavailability of PCBi, PCB-DL and PCDD/F to a soil invertebrate living at the soil surface, the ubiquitous land snail, Cantareus aspersus. Snails were caged for 28 days on 4 grassy plots with increasing POP contamination (3631 to 34942 ng.kg-1 dw for ?7 PCBi, 2 to 222 ng TEQOMS2005.kg-1 dw for ?17 PCDD/F and 1.15 to 22.8 ng TEQOMS2005.kg-1 dw for ?12 PCB-DL. An additional plot highly contaminated (>400 mg.kg-1 PCBi and sum PCDD/F + PCB-DL > 20,000 ng TEQ.kg-1) located near the studied site was also studied. Internal residues in the soft body of snails for the sum of the ?7 PCBi were from 556 to 462,124 ng.kg-1 fw whereas the ?17 congeners of PCDD/F varied from 0.052 to 1.18 ng TEQ .kg-1 and for the ?12 PCB-DL from 0.064 to 72 ngTEQ.kg-1. The ratio PCDD/F / PCB-DL was from 1 to 2.6 and the ratio PCBi/PCB-DL from 4252 to 8689. Among the PCBi, congeners 101, 138 and 153 were the most accumulated pollutants. For PCB-DL, PCB105 and 118 were the most abundant whereas for the PCDD, OCDD and HpCDD were predominant in the snail tissues. Results showed that POP are bioavailable for snails and may reach high internal body concentration in highly contaminated plots. This study provides first data on the capability of land snails to accumulate various PCB, PCB-DL and PCDD/F and reveals that these soil invertebrates may be a source of POP exposure to their consumers. Two other campaigns of biomonitoring are planned in the coming years to assess the evolution of bioavailability of POP on this polluted area, unsuitable for agricultural purposes, but that has recovered an industrial value. These studies will help to sharpen our understanding of the PCB impact on the ecosystems

Soil parameters are key factors to predict metal bioavailability to snails based on chemical extractant data.

International audienceAlthough soil characteristics modulate metal mobility and bioavailability to organisms, they are often ignored in the risk assessment of metal transfer. This paper aims to determine the ability of chemical methods to assess and predict cadmium (Cd), lead (Pb) and zinc (Zn) environmental bioavailability to the land snail Cantareus aspersus. Snails were exposed in the laboratory for 28 days to 17 soils from around a former smelter. The soils were selected for their range of pH, organic matter, clay content, and Cd, Pb and Zn concentrations. The influence of soil properties on environmental availability (estimated using HF-HClO(4), EDTA, CaCl(2), NH(4)NO(3), NaNO(3), free ion activity and total dissolved metal concentration in soil solution) and on environmental bioavailability (modelled using accumulation kinetics) was identified. Among the seven chemical methods, only the EDTA and the total soil concentration can be used to assess Cd and Pb environmental bioavailability to snails (r²(adj)=0.67 and 0.77, respectively). For Zn, none of the chemical methods were suitable. Taking into account the influence of the soil characteristics (pH and CEC) allows a better prediction of Cd and Pb environmental bioavailability (r²(adj)=0.82 and 0.83, respectively). Even though alone none of the chemical methods tested could assess Zn environmental bioavailability to snails, the addition of pH, iron and aluminium oxides allowed the variation of assimilation fluxes to be predicted. A conceptual and practical method to use soil characteristics for risk assessment is proposed based on these results. We conclude that as yet there is no universal chemical method to predict metal environmental bioavailability to snails, and that the soil factors having the greatest impact depend on the metal considered

Assessment of the bioavailability and depuration of uranium, cesium and thorium in snails ( Cantareus aspersus ) using kinetics models

International audienceUranium ore waste has led to soil contamination that may affect both environmental and soil health.To analyze the risk of metal transfer, metal bioavailability must be estimated by measuring biological parameters. Kinetic studies allow taking into account the dynamic mechanisms of bioavailability, as well as the steady state concentration in organisms necessary to take into account for relevant risk assessment. In this way, this work aims to model the snail accumulation and excretion kinetics of uranium(U), cesium (Cs) and thorium (Th). Results indicate an absence of Cs and Th accumulation showing the low bioavailability of these two elements and a strong uranium accumulation in snails related to the levels of soil contamination. During the depuration phase, most of the uranium ingested was excreted by the snails. After removing the source of uranium by soil remediation, continued snails excretion of accumulated uranium would lead to the return of their initial internal concentration, thus the potential trophic transfer of this hazardous element would stop

Combining human and snail indicators for an integrative risk assessment of metal(loid)-contaminated soils

International audienc

Use of chemical methods to assess Cd and Pb bioavailability to the snail Cantareus aspersus: A first attempt taking into account soil characteristics

International audienceBioavailability is a key parameter in conditioning contaminant transfer to biota. However, in risk assessment of terrestrial contamination, insufficient attention is being paid to the influence of soil type on trace metal bioavailability. This paper addresses the influence of soil properties on the chemical availability of cadmium (Cd) and lead (Pb)(CaCl(2) extraction and ionic activity) and bioavailability (accumulation kinetics) to the land snail Cantareus aspersus. Snails were exposed to nine contaminated soils differing by a single characteristic (pH or organic matter content or clay content) for 28 days. Toxicokinetic models were applied to determine metal uptake and excretion rates in snails and multivariate regression was used to relate uptake parameters to soil properties. The results showed that alkalinisation of soil and an increase of the organic matter content decreased Pb and Cd bioavailability to snails whereas kaolin clay had no significant influence. The CaCl(2)-extractable concentrations tended to overestimate the effects of pH when used to explain metal uptake rate. We conclude that factors other than those controlling the extractable fraction affect metal bioavailability to snails, confirming the requirement of biota measurements in risk assessment procedures. (C) 2011 Elsevier B.V. All rights reserved

Projet tripode : dynamiser la revalorisation des friches en améliorant la norme triade et en facilitant son transfert aux bureaux d’études

International audienc

Bioaccessibility of metal(loid)s in soils to humans and their bioavailability to snails: A way to associate human health and ecotoxicological risk assessment?

International audienceHuman health risk assessment (HHRA) and ecotoxicological risk assessment (ERA) of contaminated soils are frequently performed separately and based on total soil concentrations without considering the concepts of mobility, bioaccessibility and bioavailability. However, some chemical and biological assays rarely used in combination can be applied to more accurately assess the exposure of organisms to metal(loid)s and thus to better estimate the links between soil contamination and effects. For humans, the unified bioaccessibility method (UBM) assesses oral bioaccessibility, while for soil fauna such as land snails, the bioaccumulation test reflects the bioavailability of contaminants. The aim of this study is to explore the relationship between oral bioaccessibility and the bioavailability of arsenic, cadmium and lead in twenty-nine contaminated soils. The results show a modulation of bioaccumulation and bioaccessibility of metal(loid)s by soil physicochemical parameters (organic matter especially). For the three metal(loid)s studied, strong relationships were modelled between the UBM and snail tests (0.77 < r²adj.<0.95), depending on the parameters of the linear regressions (contaminant and phases of the UBM test). The original models proposed demonstrate the feasibility of linking bioaccessibility to humans and bioavailability to snails and the relevance of their association for an integrative risk assessment of contaminated soils