Corinne Perrin-Ganier

RISK OF CONTAMINATION FOR EDIBLE VEGETABLES GROWING ON SOILS POLLUTED BY POLYCYCLIC AROMATIC HYDROCARBONS

Former industrial sites represent a potential source for food chain contamination if they are converted to residential use where garden practices may be undertaken. In order to assess the risk for human health through vegetable consumption, two research programs were initiated to evaluate the bioavailability of selected PAHs and their potential transfer to edible parts of different vegetables. With this intention, we tested four methods to predict the potential contamination of vegetables growing on polluted soils (wild plant analysis, cropping of vegetables on polluted soils, models of organic pollutant transfer, soil selective chemical extractions). Various wild plant species colonized naturally the contaminated soils of former industrial sites and edible vegetables grew on these soils without symptoms of phytotoxicity. When soils presented concentrations of pollutants compatible with residential land use, no significant concentration of PAHs was measured in the different tissues. Moreover, in soils highly polluted by PAHs significant soil-root-leaf transfers of pollutants were showed, but no PAHs were found in fruits and in storage organs. We noted a similar behavior of cultivated vegetables and of their wild analogous plants facing organic pollutants. In another way, two selective chemical extraction methods correctly evaluated the soil PAH bioavailable fraction for plants growing on low-polluted soil. This would allow the use of wild plants naturally present on polluted soils in parallel with soil chemical extraction methods to assess the risk of contamination of the food chain.

Porous cups for pesticides monitoring in soil solution — Laboratory tests

Abstract In this study, preliminary tests were conducted aiming to validate the use of ceramic porous cup for collecting soil water samples and monitoring pesticides contents, as usually made for nitrates. Interactions between porous cup and pesticides were examined under different experimental conditions for three herbicides (atrazine, isoproturon, 2,4-D) and one insecticide (carbofuran). The results showed that ceramic was not inert for pesticides : as much as 80% of the applied pesticide could be retained during the flowing of the first tenth milliliters of solution. Interactions were attributed to sorption and “screening” of molecules by the porous walls and were related to the ionic character of pesticides. However, retention was not irreversible, since pesticides were quickly released by rinsing with distilled water. After these tests, porous ceramic cups could be considered as suitable samplers for pesticide determinations in soil solution, contingent on gaining further informations about soil - porous cup - pesticide interactions.

Alteration of pesticide content in the soil solution collected by a porous cup

Abstract Investigations were conducted to test the suitability of porous cups for sampling soil water to determine pesticides. Pesticide contents were controlled over a sampling period in an aqueous medium containing soluble organic matter and in a soil medium treated with atrazine or isoproturon both 14 C-labelled. The tests proved that the disturbance of pesticide concentration in the extracted water concerned only the first volume extracted (fifty milliliters). Thus, the resulting 500 ml sample had a herbicide content close to that of the corresponding leachate. The system still worked well after a dessication period or a simulated rainfall. These results confirmed clearly the usefulness of porous cups for pesticide monitoring campaigns provided the samples volume is superior to 50 ml.

Monitoring isoproturon leaching in the field by drainage and porous cup sampling

Abstract Isoproturon transfer was studied in the field by monitoring soil water sampled by porous cups or by drainage. The monitoring campaign showed early high concentrations of isoproturon in drainage water but lower levels in water from porous cups. Such differences revealed two types of water movement in soil: (l) slow movement to porous cups which allows interaction between herbicide and soil components, (2) fast flow down to drain without this possibility. The two sampling methods tended to be complementary in studying pesticide potential to reach surface and ground water.