42nd Congress of the “Groupe Français des Pesticides” (French Group of Pesticide research–GFP 2012)

The 42nd congress of the “Groupe Français des Pesticides” (French Group of Pesticide research–GFP 2012) took place 30 May–1 June at the “École Nationale Supérieure d’Ingénieurs de Poitiers” (ENSIP), a French generalist engineering grande école in Poitiers. Its focus is on the protection of the environment and is part of the University of Poitiers, one of the oldest universities in Europe. GFP is an annual conference where the latest developments in the field of pesticide research are presented. The topics most commonly discussed mainly concern environmental quality, monitoring, fate, and transfer of pesticides in the environment or risks associated with use of pesticides, but every year a key theme sets the tone. For this 42nd edition, the theme “Innovative strategies for plant protection” was retained.     

Mobility and phytoavailability of Cu,Cr, Zn,and As in a contaminated soil at a wood preservation site after 4 years of aided phytostabilization

The remediation of copper-contaminated soils by aided phytostabilisation in 16 field plots at a wood preservation site was investigated. The mobility and bioavailability of four potentially toxic trace elements (PTTE), i.e., Cu, Zn, Cr, and As, were investigated in these soils 4 years after the incorporation of compost (OM, 5 % w/w) and dolomite limestone (DL, 0.2 % w/w), singly and in combination (OMDL), and the transplantation of mycorrhizal poplar and willows. Topsoil samples were collected in all field plots and potted in the laboratory. Total PTTE concentrations were determined in soil pore water (SPW) collected by Rhizon soil moisture samplers. Soil exposure intensity was assessed by Chelex100-DGT (diffusive gradient in thin films) probes. The PTTE phytoavailability was characterized by growing dwarf beans on potted soils and analyzing their foliar PTTE concentrations. OM and DL, singly and in combination (OMDL), were effective to decrease foliar Cu, Cr, Zn, and As concentrations of beans, the lowest values being numerically for the OM plants. The soil treatments did not reduce the Cu and Zn mineral masses of the bean primary leaves, but those of Cr and As decreased for the OM and DL plants. The Cu concentration in SPW was increased in the OM soil and remained unchanged in the DL and OMDL soils. The available Cu measured by DGT used to assess the soil exposure intensity correlated with the foliar Cu concentration. The Zn concentrations in SPW were reduced in the DL soil. All amendments increased As in the SPW. Based on DGT data, Cu availability was reduced in both OM and OMDL soils, while DL was the most effective to decrease soil Zn availability.     

Reductive dechlorination of a chlorinated solvent plume in Houston,Texas

Chlorinated solvents such as tetrachloroethene (perchloroethene, PCE) and trichloroethene (TCE) have been extensively used in various industrial applications for many years. Because neither are typically consumed through their various uses, they are often released to the environment through industrial application or disposal. Once released, PCE and TCE tend to migrate downward into groundwater, where they persist. In the current case study, cheese whey was used as a groundwater amendment to facilitate the reductive dechlorination of a chlorinated solvent plume underlying an auto dealer/repair shop in Harris County, Texas. From September 2010 to January 2014, over 32,000 gallons of cheese whey were injected into the subsurface resulting in a marked reduction in oxidation–reduction potential (ORP) and nitrate concentrations, coupled with an increase in ferrous iron concentrations. Statistical trend analyses indicate the primary contaminants, PCE and TCE, as well as the daughter product cis‐1,2‐dichloroethene (cDCE), all exhibited a positive response, as evidenced by statistically decreasing trends, and/or reversal in concentration trends, subsequent to cheese whey injections. Maximum concentrations of PCE and TCE in key test wells decreased by as much as 98.97 percent and 99.17 percent, respectively. In addition, the bacterial genus Dehalococcoides, capable of complete reduction of PCE to non‐toxic ethene, was found to be more abundant in the treatment area, as compared to background concentrations. Because cheese whey is a by‐product of the cheese making process, the cost of the product is essentially limited to transport. This study demonstrates cheese whey to be an effective groundwater amendment at a cost which is orders of magnitude lower than popular industry alternatives.     

LCA to Evaluate the Environmental Impact for Chemical Pre-treatment in Plastics Metallization

The life cycle assessment methodology was used to calculate the environmental impacts of the current chemical pre-treatment with chromium(VI) for electroplating acrylonitrile butadiene styrene. The inventory comprised: the procurement of chemicals; the manufacturing process with successive baths and rinses that requires, in addition to chemicals, energy to heat baths, air agitation, filtration, and so forth, wastewater treatment and air emissions; and also the treatment of sludges from wastewater treatment and exhausted baths. Chromic acid was almost the unique responsible of eco-toxicity (97.5 %) and human toxicity-cancer (99.8 %) and it was one of the highest contributor to climate change, cumulative energy demand, fossil fuel depletion, human toxicity non-cancer, and in abiotic depletion.     

Waterfowl foraging in winter-flooded ricefields: Any agronomic benefits for farmers?

Winter-flooding of ricefields provides foraging habitat to waterfowl, which in return may bring agronomic benefits to farmers. Our study experimentally tested the effect of mallards (Anas platyrhynchos) on the standing stalks and weed seed bank in the Camargue (France), both of which present major challenges for farmers. Three duck densities were tested: (D1) 5 ducks ha⁻¹ (historical nocturnal density), (D2) 23 ducks ha⁻¹ (present nocturnal density), and (D3) 300 ducks ha⁻¹ (Asian rice-duck farming density). The ducks reduced the stalks significantly: −27 % (D1), −52 % (D2), and −91 % (D3). Conversely, they decreased the number of seeds by only 3 % (D3) and the seed mass by about 21 % (D1 and D3), which was not significant. Besides they had no effect on seed species richness. This study clearly demonstrates that the winter-flooding effect on straw decomposition can be enhanced by waterfowl foraging, hence showing an agronomic benefit from ducks to farmers. However, there was no clear effect in terms of seed bank reduction.     

Ecological assessment of French Atlantic lakes based on phytoplankton, phytobenthos and macrophytes

Biological elements, including phytoplankton, phytobenthos, macrophytes, benthic invertebrates and fish, are employed by the EU Water Framework Directive (WFD) 2000/60/EC as ecological indicators for the assessment of surface waters. The use of primary producers (phytoplankton, phytobenthos and macrophytes) for water quality assessment has a long history, and several methods have been developed worldwide. In this study, we used these three communities to assess the ecological status of five natural lakes located in the Aquitaine region (southwest France). Several biological indices used in lakes from other European countries or in French rivers were employed and compared among the three communities. Each primary producer provided complementary information about the ecological status of the lakes, including the invasiveness of exotic taxa. Regardless of the producer community used, the response to the environment, as reflected by the indices (adequate for each community), was similar: Lakes Cazaux, Lacanau and Hourtin showed the best ecological status and Parentis and Soustons the worst. Phytoplankton diagnosis reflected and integrated unambiguously the water quality of the lakes, as demonstrated by the strong relationships between the phytoplankton index and the trophic status criteria. This community appeared as the best indicator, especially when macrophytes were absent. The methods applied here represent a potential tool for the assessment of the ecological status in the context of WFD, but they need to be refined. We propose modifications for phytobenthos index initially tailored for running waters for adequate use in lentic ecosystems. Indices for the three primary producers should be modified to incorporate exotic species which may provide information on potential biodiversity losses.     

Assessment of successful experiments and limitations of phytotechnologies: contaminant uptake, detoxification and sequestration, and consequences for food safety

Purpose  

The term “phytotechnologies” refers to the application of science and engineering to provide solutions involving plants, including phytoremediation options using plants and associated microbes to remediate environmental compartments contaminated by trace elements (TE) and organic xenobiotics (OX). An extended knowledge of the uptake, translocation, storage, and detoxification mechanisms in plants, of the interactions with microorganisms, and of the use of “omic” technologies (functional genomics, proteomics, and metabolomics), combined with genetic analysis and plant improvement, is essential to understand the fate of contaminants in plants and food, nonfood and technical crops. The integration of physicochemical and biological understanding allows the optimization of these properties of plants, making phytotechnologies more economically and socially attractive, decreasing the level and transfer of contaminants along the food chain and augmenting the content of essential minerals in food crops. This review will disseminate experience gained between 2004 and 2009 by three working groups of COST Action 859 on the uptake, detoxification, and sequestration of pollutants by plants and consequences for food safety. Gaps between scientific approaches and lack of understanding are examined to suggest further research and to clarify the current state-of-the-art for potential end-users of such green options.     

The anthropogenic atmospheric elements fraction: A new interpretation of elemental deposits on tree barks

The superficial deposit on the bark surface of several trees (mainly Fraxinus excelsior L.) was sampled in the experimental station of the university campus in Grenoble (France). Its composition was studied by scanning electron microscopy–energy dispersive X-ray emission (SEM–EDX) and, after digestion, by inductively coupled plasma-mass spectrometry (ICP-MS). The deposit was composed of 81.3% ± 7.4 organic matter, 9.4% ± 4.9 of geogenic minerals issued from the atmosphere (atmospheric geogenic fraction: AGF) and 9.3% ± 2.7 of a mixture of elements which was called anthropogenic atmospheric elements fraction (AAEF). The SEM–EDX analysis showed the presence of particles of geogenic compounds such as different types of silicates, phosphates, carbonates, sulphates, oxides and also particles of metals such as iron or of alloys of Fe–Zn, Fe–Ni, Ni–Cr and Ca sulphates or phosphates. Typical spheres of “fly ashes” composed of pure iron or Al-silicates were detected. Using the SEM–EDX analysis of the deposit and the average local soil composition, an empiric formula for the AGF (without polluting elements) was chosen, which presented a clear analogy with the global formula of the upper continental crust. In the same way, a formula for the pure organic matter fraction was chosen. Withdrawing the elements corresponding to these two fractions allows a tentative estimation of the content of the AAEF which was supposed to better represent the elemental anthropogenic contamination issued from the atmosphere. In the station, most of Sb, Cd, Sn, Pb, Cu, V and Zn were found in the AAEF. This AAEF composition was compared to that of the deposit in a highway tunnel where Pb and Cu were at a very high level. The meaning and the limits of the AAEF concept were critically discussed.     

Realistic approach of pesticide residues and French consumer exposure within fruit & vegetable intake

The increase of fruit and vegetable (F&V) intake contributes to the prevention of chronic diseases, but could also significantly increase pesticide exposure and may thus be of health concern. Following a previous pesticide exposure assessment study, the present study was carried out to determine actual levels of pesticides within 400 g of F&V intake and to evaluate consumer risk. Forty-three Active Substances (AS) exceeding 10 % of the Acceptable Daily Intake (ADI) in balanced menus established for our previous theoretical study were considered. Fifty-six pooled food samples were analyzed: 28 fruit samples and 28 vegetable samples. Pesticide values were compared to Maximum Residue Levels (MRL) and to the "toxicological credit" derived from ADI. It was observed that 23 out of the 43 retained AS were never detected, 5 were detected both in F&V samples, 12 only in fruits and 3 only in vegetables. The most frequently detected AS were carbendazim, iprodione and dithiocarbamates. When detected, AS were more frequently found in fruit samples (74 %) than in vegetable samples (26 %). A maximum of 3 AS were detected at once in a given sample. Overall, we observed 8 and 14 overruns of the MRL in 1204 measures in pooled vegetable and fruit samples, respectively (0.7 % and 1.2 % of cases, respectively). Chronic exposure for adults was the highest for dithiocarbamates but did not exceed 23.7 % of the ADI in F&V. It was concluded that raising both F&V consumption up to 400 g/day (~5 F&V/day) according to recommendations of the national health and nutrition plan, does not induce pesticide overexposure and should not represent a risk for the consumer.     

Plankton filtration with compressible crumb rubber packs

The experiments described provide insight into the feasibility of using compressible particulate packs to filter live plankton. The pore constriction sizes are controlled by subjecting the filter pack to isotropic confinement, thereby allowing for: (1) enhanced filtration upon confinement and (2) enhanced unclogging upon relaxation. Results show that filtration efficiency increases with increasing confinement; however, complete plankton retention is difficult to attain due to the plankton’s ability to pass through pore constrictions that are smaller than the plankton size. The results are anticipated to offer potential benefits to ballast treatment and aquatic filtration operations.