The toxicity associated with suspended sediments from the Rhone River (Switzerland-France) was determined with three acute bioassays. Large volume water samples were centrifuged for recovery of suspended solids in November 1989; one sample was taken as a control upstream from Lake Geneva and the 9 remainder downstream from Geneva to the Mediterranean Sea, with a single sample of the major tributary the Saone at Lyon. Heavy metals (Hg, Cd, Cr, Cu, Ni, Pb, Zn) and organic contaminants (OCs, PCBs, PAHs) bound to sediment were analysed and extracted by elutriation with filtered lake water and by organic solvent ( dichloromethane ). Sediment water elutriates were tested with algal fractionation bioassays (AFB) using Lake Geneva ambient phytoplankton, with Daphnia magna and Microtox® acute toxicity tests, whereas organic extracts were utilized in the latter two bioassays to evaluate the potential sediment toxicity. The bulk analyses of the sediment together with elutriate metal concentrations indicated the highest contamination of sediment downstream of Lyon. Medium contamination appeared for the stations downstream of Geneva, in the Saone River and at the Rhone River mouth. The station upstream of Lyon had low concentrations, comparable to the values in the Upper Rhone. Organic contaminants are mainly observed downstream of Lyon and their concentrations decline onwards to the sea. The bioassays Microtox ® on organic extracts and AFB on the elutriates show a similar toxicity trend, but differ in that Microtox was more sensitive to organics whereas the algal test responded predominantly to metals. This difference is believed to be due to the different extraction procedures used, rather than to the tests themselves. Daphnia magna was the least sensitive and appeared to give a broader band response to the observed contaminants in the sediment. The bioassay results when integrated confirm that the biotoxicity trends relate well to the composition of the sediment, a factor which emphasizes the need for battery testing in ecotoxicological assessment
Ten large volume water samples were taken from the RhBne River (Switzerland-France) in November 1989 for recovery of total suspended sediment by continuous flow centrifugation. The samples were freeze-dried and analysed for particle size, organic carbon, total nitrogen, and carbonate. For comparative purposes, four bed sediments collected in July 1989 are also described. The RhBne can be subdivided into three sections on the basis of the origins of the water. The first section is the Upper RhBne River draining into Lake Geneva. Waters are derived from glaciers, with low temperature and conductivity and high turbidity. Suspended sediment is coarse, has a bimodal distribution, and is low in both organic matter and carbonate. The second reach is from Lake Geneva to the confluence with the Sabne at Lyon and has warmer water with higher conductivity and very low turbidity. Suspended sediment is higher in organic matter, with high carbonate originating from the lake. The final section is from Lyon to Arles, with warmer water and higher conductivity and turbidity due to modification by the SaBne. Sediment is rich in organic matter, which may account for an observed decline in oxygen in the river waters downstream from Lyon. Carbonate in these sediments also decreases due to increased turbidity from the SaBne. Suspended sediments other than from the Upper RhBne show a remarkable consistency in grain size, predominantly in the fine silts (mode 9-11 pm). This consistency indicates a high degree of suitability for geochemical analysis. Bed sediments were bimodal throughout, with a dominant coarse population in two out of the four samples. Grain size statistical parameters could be easily explained by application of the theory of mixing of two major populations in the sand size (bed traction load) and the fine silt/clay size (suspended sediment load).KEY WORDS Sediments Rhbne River Particle size 088 5 -608 7/92/02022 7 -1
Cyst‐based ecotoxicological tests are simple and low‐cost methods for assessing acute toxicity. Nevertheless, only a few comparative studies on their sensitivity are known. In the present study, the suitability of the use of two freshwater Anostracan species, Streptocephalus rubricaudatus and S. texanus, was assessed. The impact of 16 priority pollutants (4 heavy metals, 11 organic, and 1 organometallic compounds) on these two species, as well as on Artemia salina (Artoxkit M), Daphnia magna (International Organization for Standardization 6341), and S. proboscideus (Streptoxkit F) was assessed. For indicative comparison, bioassays using Brachionus calyciflorus (Rotoxkit F) and Photobacterium phosphoreum (Microtox) were also performed. For heavy metals (K2Cr2O7, Cd2+, Zn2+, Cu2+), the sensitivity of the two studied Streptocephalus species was slightly higher than that of D. magna. It was significantly more elevated than for the marine A. salina. For organic and organometallic micropollutants [phenol, 3,5‐dichlorophenol, pentachlorophenol (PCP), hydroquinone, linear alkylbenzene sulfonate, sodium dodecyl sulfate, tributylphosphate, dimethylphthalate, atrazine, lindane, malathion, tributyltin chloride (TBT‐CI)], the sensitivity of the 4 anostracan species was of the same order of magnitude as that of D. magna. Artemia salina was slightly less sensitive to some organic compounds (PCP, hydroquinone, TBT‐CI). The sensitivity of S. rubricaudatus to organic solvents was low. On the other hand, this anostracan was quite sensitive to NaCI. Thus, its use is restricted to freshwater samples. The evaluation of global practicability of these two tests confirms that cyst‐based freshwater anostracans may be used to perform low‐cost tests at a sensitivity comparable to that of D. magna (24 h immobilization test). © 1994 by John Wiley & Sons, Inc..
The dehydrogenase activity (DHA) of the microflora of a gleyic luvisol artificially contaminated by 1, 10, and 100 pg tributylin (TBT)/g dry wt soil was compared with its ATP content, long-term C02 evolution, and esterase activity. DHA was measured by reduction of triphenyltetrazolium chloride. This 203-day laboratory experiment comprised a phase of air drying, a remoistening, and the addition of a substrate (alfalfa and yeast extract). The half-life of TBT ranged from 40 (10 and 100 ygig) up to 70 days (1 pg/g).The microflora was not affected by 1 and 10 p g TBTlg. After an initial 60% stimulation, the respiration and esterase activity in the soil contaminated by 100 pg TBTig recovered to the level of the control soil in 2 and 14 days, respectively. About 50% depression of DHA and ATP content was observed throughout the 203 days of the experiment. DHA inhibition was correlated with depression of ATP content ( r = 0.82). Air drying, remoistening, and substrate addition had little influence on the depression of DHA and of the ATP content.Unlike long-term C 0 2 evolution, DHA did not reflect the total effective activity of soil microflora; rather, it reflected its total potential activity. As for biomass estimates using substrate-induced respiration, a clear distinction should be made between shortterm DHA and other measurements of DHA. Short-term DHA, as a substrate-induced maximum initial activity, appears mainly to reflect the biomass of soil microflora. The measurement of DHA appears to be a suitable low-cost and sensitive tool for assessing side effects of chemicals.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.