Validation of chlordecone analysis for native and remediated French West Indies soils with high organic matter content.

An analytic method was developed and validated for the analysis of chlordecone in the three main types of French West Indies soils: Ferralsol, Andosol and Nitisol with and without the addition of Daramend® and compost amendment used in a remediation process. The method consists in analysis by gas chromatography coupled with triple quadrupole mass spectrometry after pressurised liquid extraction. The high natural content of organic matter in the soils coupled with the additional exogenous organic matter from the amendments tested lead to a complex extract. Trans-nonachlor was used as surrogate to correct the results for extraction efficiency, and (13)C chlordecone was added as internal standard to mimic as closely as possible the behaviour of chlordecone and suppress possible side effects during its analysis. The key parameters of the method (linearity, repeatability, interday precision, specificity, extraction efficiency and limit of quantification) were validated in accordance with the NF T 90-210 standard method. The limit of quantification is 0.03 mg/kg. Uncertainty (k = 2) was 40 % for concentrations lower than or equal to 1 mg/kg, and 30 % for concentrations greater than 1 mg/kg.

Decontamination of a polychlorinated biphenyls-contaminated soil by phytoremediation-assisted bioaugmentation.

A 70 day pot experiment was conducted for the cleaning-up of a PCBs-contaminated soil (104 mg kg(-1) soil DW) using bioaugmentation with Burkholderia xenovorans LB400 (LB400) assisted or not by the use of tall fescue (Festuca arundinacea). The total cultivable bacteria of the soil were higher with the presence of plants. Real-time PCR showed that LB400 (targeting 16S-23S rRNA ITS) survived with abundance related to total bacteria (targeting 16S rRNA) being higher with fescue (up to a factor of three). Bioaugmentation had a positive effect on fescue biomass and more specifically on roots (by a factor of three). PCB dissipation (sum of congeners 28, 52, 101, 118, 153, 180) averaged 13 % (bioaugmented-planted) up to 32 % (non bioaugmented-planted), without any significant difference between treatments. Basically our results demonstrated that indigenous bacteria were able to dissipate PCBs (26.2 % dissipation). PCB dissipation was not related to the abundance of LB400 or to the total bacterial counts. Bioaugmentation or fescue altered the structure of the bacterial community of the soil, not the combination of both. Principal component analysis showed that bioaugmentation tended to improve the control of the process (lower variability in PCB dissipation). Opposite to that bioaugmentation increased the variability of the structure of the bacterial community.

Comparison of the effects of two herbicides and an insecticide on tropical freshwater plankton in microcosms.

Natural plankton communities from a tropical freshwater reservoir (Combani Reservoir, Mayotte Island, Mozambique Channel) were exposed, in 20-l nutrient-enriched microcosms, to two nominal concentrations of three pesticides: the herbicides diuron (2.2 and 11 µg/l) and paraquat (10 and 40.5 µg/l) and the insecticide fenitrothion (10 and 100 µg/l), commonly used in the tropics for agriculture and disease vector control. Bacterioplankton, phytoplankton, and zooplankton communities were monitored for 5 days after exposure, and the concentrations of toxicant and major nutrients were measured. Bacterioplankton growth was noticeable in all systems and was slightly affected by pesticide at any concentration. A transitory increase in thymidine-based bacterial production was observed in diuron- and fenitrothion-treated microcosms, followed by a marked decrease in all microcosms after 5 days. The functional diversity of bacterioplankton, evaluated using BIOLOG ECO(®) microplates, was reduced by exposure to the highest pesticide concentrations. Phytoplankton was affected by pesticides in different ways. Chlorophyll biomass and biovolumes were increased by diuron addition and decreased by paraquat, whereas fenitrothion-treated microcosms remained unaffected relative to controls. Phytoplankton taxonomic diversity was decreased by paraquat and high doses of fenitrothion but was unaffected by addition of diuron. The decrease in diversity was due to a reduction in the number of species, whereas the density of small cells increased, especially after addition of paraquat. Heterotrophic flagellates were sensitive to paraquat and to the highest diuron concentration; a reduction in biomass of up to 90% was observed for 40.5 µg/l paraquat. Zooplankton, dominated by Thermocyclops decipiens and Diaphanosoma excisum, was slightly sensitive to diuron, and very sensitive to paraquat. High concentrations of the insecticide fenitrothion were effective only on young stages. The potential direct and indirect effects of pesticide contamination on such a simplified plankton food web, typical of newly constructed reservoirs, appear to differ significantly depending on the biological compartment considered. The overall sensitivity of tropical plankton is comparable to the sensitivity for temperate systems, and direct and indirect effects appeared rapidly, within 5 days of exposure.

Molecularly imprinted polymer applied to the determination of the residual mass of atrazine and metabolites within an agricultural catchment (Brévilles, France).

Atrazine, desethyl-atrazine and desisopropyl-atrazine have been measured in the soils of Brévilles watershed. Pressurised liquid extraction (PLE) technique was used for extraction followed by purification with terbutylazine molecularly imprinted polymers. This clean-up procedure allowed to remove interfering compounds from the sample extracts. Thus making easier the analyses by reversed phase liquid chromatography coupled with ion trap tandem mass spectrometry. This selective sample treatment for soil extracts allowed limit of quantification (LOQ) of 0.03 ng/g for atrazine and 0.05 ng/g for metabolites. The concentrations in soil samples ranged from 7.1 ng/g to < LOQ for atrazine and from 2.5 ng/g to < LOQ for metabolites. The total cumulated mass in the top 60 cm of the soil of the watershed was estimated at 1.4, 0.52 and 0.25 kg for atrazine, desethyl-atrazine and desisopropyl-atrazine, respectively. A fraction of this mass available for leaching could generate water infiltrating with concentrations higher than the drinking water limit, 7 years after the last application of atrazine.

Molecularly imprinted polymer dedicated to the extraction of glyphosate in natural waters.

Three molecularly imprinted polymers (MIPs) have been synthesized in order to bind efficiently glyphosate (GLY) in natural waters (mineral and underground). Since the target analyte is polar and hydrophilic, electrostatic interactions and hydrogen bonds have been favored with two templates (phenylphosphonic acid and diethyl(α-aminobenzyl)-phosphonic acid) and two functional monomers (1-allyl-2-thiourea and methacrylic acid). MIPs have been assessed by comparison of the recoveries obtained with MIP and NIP (non imprinted polymer) by solid-phase extraction (SPE). The selectivity of MIP versus NIP was satisfactory for the three imprinted polymers with a very straightforward protocol: conditioning of 250 mg of MIP or NIP packed in 3-mL polypropylene cartridges with 3 mL Milli-Q water, loading of Milli-Q water (15 mL) spiked with 5 mg L(-1) of GLY and its metabolite, aminomethylphosphonic acid (AMPA) and elution by 3 mL NH4OH (10mM) or 3 mL HCl (100mM). SPE fractions were directly analyzed by capillary electrophoresis (CE). Thus, the recoveries of both analytes were greater than 80% for all MIPs and less than 25% for most NIPs. Moreover, the MIP prepared with 1-allyl-2-thiourea as functional monomer and phenylphosphonic acid as template displayed a capacity of 0.033 µmol/mg for GLY. However, the substitution of Milli-Q water by mineral water caused the decrease of MIP recoveries, for that, a pretreatment of the sample by ionic exchange resins was set up and succeeded in improving recoveries (about 50% for GLY and 25% for AMPA). Then, groundwaters were spiked with low concentrations of GLY and AMPA (0.5 µgL(-1)) and directly percolated through MIP cartridges. The extractions were carried out by triplicate and the elution fractions were analyzed by UPLC-MS/MS. The results showed no retention of AMPA but a total retention of GLY by MIP.