... Titre du document / Document title. Effects of nutrient loading and insecticide application o... more ... Titre du document / Document title. Effects of nutrient loading and insecticide application on the ecology of Elodea-dominated freshwater microcosms. I: Responses of plankton and zooplanktivorous insects. Auteur(s) / Author(s). ...
Use of the insecticide lambda‐cyhalothrin in agriculture may result in the contamination of water... more Use of the insecticide lambda‐cyhalothrin in agriculture may result in the contamination of water bodies, for example by spray drift. Therefore, the possible exposure of aquatic organisms to this insecticide needs to be evaluated. The exposure of the organisms may be reduced by the strong sorption of the insecticide to organic materials and its susceptibility to hydrolysis at the high pH values in the natural range. In experiments done in May and August, formulated lambda‐cyhalothrin was mixed with the water body of enclosures in experimental ditches containing a bottom layer and macrophytes (at different densities) or phytoplankton. Concentrations of lambda‐cyhalothrin in the water body and in the sediment layer, and contents in the plant compartment, were measured by gas‐liquid chromatography at various times up to 1 week after application. Various water quality parameters were also measured. Concentrations of lambda‐cyhalothrin decreased rapidly in the water column: 1 day after a...
The effects of a pesticide mixture (asulam, fluazinam, lambda-cyhalothrin, and metamitron) on aqu... more The effects of a pesticide mixture (asulam, fluazinam, lambda-cyhalothrin, and metamitron) on aquatic ecosystems were investigated in 20 outdoor aquatic microcosms. Ten of the microcosms simulated mesotrophic aquatic ecosystems dominated by submerged macrophytes (Elodea). The others simulated eutrophic ecosystems with a high Lemna surface coverage (Lemna). This paper describes the fate of the chemicals as well as their effects on the growth of Myriophyllum spicatum and the periphytic algal community. In the Elodea-dominated microcosms significant increase in the biomass and alterations of species composition of the periphytic algae were observed, but no effect on M. spicatum growth could be recorded in response to the treatment. The opposite was found in the Lemna-dominated microcosms, in which decreased growth of M. spicatum was observed but no alterations could be found in the periphytic community. In the Elodea-dominated microcosms the species composition of the periphytic algae diverged from that of the control following treatment with 0.5% spray drift emission of the label-recommended rate (5% for lambda-cyhalothrin), while reduced growth of M. spicatum in the Lemna-dominated microcosms was recorded at 2% drift (20% for lambda-cyhalothrin). This study shows that the structure of the ecosystem influences the final effect of pesticide exposure.
The fungicide fluazinam, the insecticide lambda-cyhalothrin, and the herbicides asulam and metami... more The fungicide fluazinam, the insecticide lambda-cyhalothrin, and the herbicides asulam and metamitron were applied to indoor freshwater microcosms (water volume approximately 0.6 m3). The treatment regime was based on a realistic application scenario in tulip cultivation. Concentrations of each pesticide were equal to 0%, 0.2%, 0.5%, 2%, and 5% spray drift emission of label-recommended rates. Contribution of compounds to the toxicity of the pesticide package was established by expressing their concentrations as fractions of toxic units. The fate of the compounds in the water, and responses of phytoplankton, zooplankton, periphyton, macroinvertebrates, macrophytes, decomposition, and water quality were followed for 13 weeks. The half-lives of lambda-cyhalothrin, metamitron, and fluazinam were 1 to 2 d; that of asulam was >30 d. No consistent effects could be demonstrated for the 0.2% treatment regime that was therefore considered the no-observed-effect concentration community (NOEC). The macroinvertebrate populations of Gammarus pulex, Asellus aquaticus, and Proasellus meridianus were the most sensitive end points, followed by species of copepods and cladocerans. Responses mainly were due to lambda-cyhalothrin. The 0.5% treatment regime resulted in short-term effects. Pronounced effects were observed at the 2% and 5% treatment levels. At the end of the experiment, the macrophyte biomass that consisted of Elodea nuttallii, showed a decline at the two highest treatment levels, asulam being the causal factor (NOEC: 0.5% treatment level). Primary production was reduced at the 5% treatment level only. In our experiment, the first-tier risk assessment procedure for individual compounds was adequate for protecting sensitive populations exposed to realistic combinations of pesticides. Spray drift reduction measures seem to be efficient in protecting aquatic ecosystems in agricultural areas.
Analytical and bioanalytical chemistry, Jan 2, 2018
Certification of trace metals in seawater certified reference materials (CRMs) NASS-7 and CASS-6 ... more Certification of trace metals in seawater certified reference materials (CRMs) NASS-7 and CASS-6 is described. At the National Research Council Canada (NRC), column separation was performed to remove the seawater matrix prior to the determination of Cd, Cr, Cu, Fe, Pb, Mn, Mo, Ni, U, V, and Zn, whereas As was directly measured in 10-fold diluted seawater samples, and B was directly measured in 200-fold diluted seawater samples. High-resolution inductively coupled plasma mass spectrometry (HR-ICPMS) was used for elemental analyses, with double isotope dilution for the accurate determination of B, Cd, Cr, Cu, Fe, Pb, Mo, Ni, U, and Zn in seawater NASS-7 and CASS-6, and standard addition calibration for As, Co, Mn, and V. In addition, all analytes were measured using standard addition calibration with triple quadrupole (QQQ)-ICPMS to provide a second set of data at NRC. Expert laboratories worldwide were invited to contribute data to the certification of trace metals in NASS-7 and CASS...
Greenhouse soils are regularly treated with metham-sodium, which in soil is quickly transformed t... more Greenhouse soils are regularly treated with metham-sodium, which in soil is quickly transformed to the fumigant methyl isothiocyanate. An experimental fumigation was carried out in a greenhouse with sandy soil. Data were collected on the behavior of methyl isothiocyanate in soil and its permeation through a film of low-density polyethene (LDPE) covering the soil. This cover was found to be
... Titre du document / Document title. Effects of nutrient loading and insecticide application o... more ... Titre du document / Document title. Effects of nutrient loading and insecticide application on the ecology of Elodea-dominated freshwater microcosms. I: Responses of plankton and zooplanktivorous insects. Auteur(s) / Author(s). ...
Use of the insecticide lambda‐cyhalothrin in agriculture may result in the contamination of water... more Use of the insecticide lambda‐cyhalothrin in agriculture may result in the contamination of water bodies, for example by spray drift. Therefore, the possible exposure of aquatic organisms to this insecticide needs to be evaluated. The exposure of the organisms may be reduced by the strong sorption of the insecticide to organic materials and its susceptibility to hydrolysis at the high pH values in the natural range. In experiments done in May and August, formulated lambda‐cyhalothrin was mixed with the water body of enclosures in experimental ditches containing a bottom layer and macrophytes (at different densities) or phytoplankton. Concentrations of lambda‐cyhalothrin in the water body and in the sediment layer, and contents in the plant compartment, were measured by gas‐liquid chromatography at various times up to 1 week after application. Various water quality parameters were also measured. Concentrations of lambda‐cyhalothrin decreased rapidly in the water column: 1 day after a...
The effects of a pesticide mixture (asulam, fluazinam, lambda-cyhalothrin, and metamitron) on aqu... more The effects of a pesticide mixture (asulam, fluazinam, lambda-cyhalothrin, and metamitron) on aquatic ecosystems were investigated in 20 outdoor aquatic microcosms. Ten of the microcosms simulated mesotrophic aquatic ecosystems dominated by submerged macrophytes (Elodea). The others simulated eutrophic ecosystems with a high Lemna surface coverage (Lemna). This paper describes the fate of the chemicals as well as their effects on the growth of Myriophyllum spicatum and the periphytic algal community. In the Elodea-dominated microcosms significant increase in the biomass and alterations of species composition of the periphytic algae were observed, but no effect on M. spicatum growth could be recorded in response to the treatment. The opposite was found in the Lemna-dominated microcosms, in which decreased growth of M. spicatum was observed but no alterations could be found in the periphytic community. In the Elodea-dominated microcosms the species composition of the periphytic algae diverged from that of the control following treatment with 0.5% spray drift emission of the label-recommended rate (5% for lambda-cyhalothrin), while reduced growth of M. spicatum in the Lemna-dominated microcosms was recorded at 2% drift (20% for lambda-cyhalothrin). This study shows that the structure of the ecosystem influences the final effect of pesticide exposure.
The fungicide fluazinam, the insecticide lambda-cyhalothrin, and the herbicides asulam and metami... more The fungicide fluazinam, the insecticide lambda-cyhalothrin, and the herbicides asulam and metamitron were applied to indoor freshwater microcosms (water volume approximately 0.6 m3). The treatment regime was based on a realistic application scenario in tulip cultivation. Concentrations of each pesticide were equal to 0%, 0.2%, 0.5%, 2%, and 5% spray drift emission of label-recommended rates. Contribution of compounds to the toxicity of the pesticide package was established by expressing their concentrations as fractions of toxic units. The fate of the compounds in the water, and responses of phytoplankton, zooplankton, periphyton, macroinvertebrates, macrophytes, decomposition, and water quality were followed for 13 weeks. The half-lives of lambda-cyhalothrin, metamitron, and fluazinam were 1 to 2 d; that of asulam was >30 d. No consistent effects could be demonstrated for the 0.2% treatment regime that was therefore considered the no-observed-effect concentration community (NOEC). The macroinvertebrate populations of Gammarus pulex, Asellus aquaticus, and Proasellus meridianus were the most sensitive end points, followed by species of copepods and cladocerans. Responses mainly were due to lambda-cyhalothrin. The 0.5% treatment regime resulted in short-term effects. Pronounced effects were observed at the 2% and 5% treatment levels. At the end of the experiment, the macrophyte biomass that consisted of Elodea nuttallii, showed a decline at the two highest treatment levels, asulam being the causal factor (NOEC: 0.5% treatment level). Primary production was reduced at the 5% treatment level only. In our experiment, the first-tier risk assessment procedure for individual compounds was adequate for protecting sensitive populations exposed to realistic combinations of pesticides. Spray drift reduction measures seem to be efficient in protecting aquatic ecosystems in agricultural areas.
Analytical and bioanalytical chemistry, Jan 2, 2018
Certification of trace metals in seawater certified reference materials (CRMs) NASS-7 and CASS-6 ... more Certification of trace metals in seawater certified reference materials (CRMs) NASS-7 and CASS-6 is described. At the National Research Council Canada (NRC), column separation was performed to remove the seawater matrix prior to the determination of Cd, Cr, Cu, Fe, Pb, Mn, Mo, Ni, U, V, and Zn, whereas As was directly measured in 10-fold diluted seawater samples, and B was directly measured in 200-fold diluted seawater samples. High-resolution inductively coupled plasma mass spectrometry (HR-ICPMS) was used for elemental analyses, with double isotope dilution for the accurate determination of B, Cd, Cr, Cu, Fe, Pb, Mo, Ni, U, and Zn in seawater NASS-7 and CASS-6, and standard addition calibration for As, Co, Mn, and V. In addition, all analytes were measured using standard addition calibration with triple quadrupole (QQQ)-ICPMS to provide a second set of data at NRC. Expert laboratories worldwide were invited to contribute data to the certification of trace metals in NASS-7 and CASS...
Greenhouse soils are regularly treated with metham-sodium, which in soil is quickly transformed t... more Greenhouse soils are regularly treated with metham-sodium, which in soil is quickly transformed to the fumigant methyl isothiocyanate. An experimental fumigation was carried out in a greenhouse with sandy soil. Data were collected on the behavior of methyl isothiocyanate in soil and its permeation through a film of low-density polyethene (LDPE) covering the soil. This cover was found to be
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