Kristin Becker-van Slooten

Toxic effects of Irgarol 1051 on phytoplankton and macrophytes in Lake Geneva

Irgarol 1051 is a recent herbicidal compound, inhibitor of photosynthesis, used in antifouling paints. This toxic is persistent in aquatic environments, with low abiotic and biotic degradation, highly phytotoxic, and has already been detected in estuaries and coastal areas, with suspected negative impacts on non-target organisms (aquatic plants and algae). We measured the toxicity of Irgarol 1051 to macrophytes and phytoplankton from Lake Geneva (between Switzerland and France) by determining chlorophyll fluorescence yield, and phytoplankton primary production. Long-term toxicity for phytoplankton was estimated in a microcosm study, and growth inhibition tests were performed with isolated algal strains. The concentration of Irgarol 1051 was analysed in the water, and the most polluted site showed a higher level (up to 135 ng/L) than the lowest observed effect concentration for phytoplankton (8-80 ng/L), while the macrophytes appeared to be more tolerant to Irgarol 1051 in short-term tests. The microcosm study showed that phytoplankton structure might be even more sensitive to Irgarol 1051.

Determination of water quality standards for chemical mixtures: extension of a methodology developed for herbicides to a group of insecticides and a group of pharmaceuticals.

Monitoring surveys throughout America and Europe have demonstrated the widespread presence of organic synthetic substances such as pesticides and pharmaceuticals in surface water. To avoid deleterious effects on the aquatic system, many countries determine water quality criteria for pesticides. For each substance, the comparison of the concentration measured in water with its criterion gives an indication of the pressure this substance put on the aquatic system. However, in the environment, aquatic organisms are not only exposed to single pesticides but typically to mixtures of these substances. It is therefore of particular importance to take mixtures into account when defining water quality criteria, which is rarely done yet. We recently developed a method to define consistent and comparable water quality criteria for mixtures of herbicides having a similar mode of action. These criteria are calculated based on species sensitivity curves; the method assumes that these curves are parallel for substances having similar mode of action. The aim of this study was to apply our method to six organophosphates (insecticides) and to three β-blockers (pharmaceuticals), other groups of compounds commonly detected in surface water. We found some evidence that the developed methodology gives consistent results for these groups too. The hypothesis of parallelism was accepted in 2/3 (β-blockers) and 2/6 of the cases (organophosphates) for both species sensitivity curves based on effect concentrations 50% and on no-observed effect concentrations. The use of water quality criteria for mixture is illustrated by two case studies, which show the importance of taking mixtures into account in water quality legislation.

BOD5 measurements of water presenting inhibitory Cu2+ : implications in using of BOD to evaluate biodegradability of industrial wastewaters

In industrial effluents, the presence of an infinite number of possible mixtures of substances and the high variability of chemical conditions ask for an evaluation of biodegradability by a global and simple method. Biological oxygen demand after five days (BOD5) using synthetic wastewater was studied by two different ways: dilution and manometric methods. It can therefore be established that BOD5 obtained by adding manufactured inocula to the synthetic medium (effluent containing known and easily biodegradable substances) is close to the values obtained with inocula taken from the treated effluent of an urban and a rural purification plant. It was found that BOD5 measurement of effluents presenting factors affecting biodegradation, similar of those found in industrial effluents, is very questionable. The BOD is in this case influenced by the synergic and antagonist interactions between numerous and variable parameters like as pH, nature and concentration of inoculum, concentration of nutriments, amount and nature of assimilable substances, presence of toxicants, and presence of nitrification inhibitors, which are typical of real industrial wastewaters.

Toxicity of sediments from the Ho Chi Minh City canals and Saigon River, Viet Nam

Toxicity of sediment from waterways of Ho Chi Minh City (HCMC), Viet Nam, was assessed in aqueous and organic extracts using the organisms Daphnia magna and Vibrio fischeri. Sediment samples were taken along the main canals of HCMC and in the Saigon river. The results indicate a relatively high potential toxicity of the extracts, especially concerning the aqueous extracts. V. fischeri shows a higher sensitivity than D. magna for both types of extracts. Sediments from the canals in the urban areas, where the industrial and domestic activities are concentrated, indicate a higher potential toxicity than sediments from the river. Organic extracts of deep sediments (about 1.3 m) are less toxic than surface sediment. The toxicity of the organic sediment extracts was higher in 1999 than in 1996, except for one site, where dredging operations have been carried out since 1997. The dredging operations thus have a positive local effect on the sediment quality, but further consequences on water and sediment quality of HCMC canals and rivers still have to be evaluated. © 2000 John Wiley & Sons, Inc. Environ Toxicol 15: 469–475, 2000

Micropollutants in the sediment of the SaiGon-DongNai river: Situation and ecological risks

Reference CECOTOX-ARTICLE-2003-005View record in Web of Science URL: http://www.sach.ch/doc/chimia/sept03/anh.pdf Record created on 2005-07-15, modified on 2016-08-08