Effect of humic substances on remediation of soil- phosphogypsum mixturesтезисы доклада

Дата последнего поиска статьи во внешних источниках: 28 мая 2015 г.

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[1] Effect of humic substances on remediation of soil- phosphogypsum mixtures / M. Kaniskin, B. Terekhova, A. Izosimov, O. Yakimenko // SETAC 6th World Congress/SETAC Europe 22nd Annual Meeting http://berlin.setac.eu/embed/Berlin/Abstractbook2_Part2.pdf. — Vol. 2. — SETAC Berlin, 2012. — P. 350–350. Phosphogypsum (PG) is waste material in industrial production of phosphoric acid . Due to high content of nutrients (calcium, phosphorus and sulfur) it is sometimes used as a fertilizer for poor unfertile soils . But besides nutrients, PG also contains toxic impurities, such as fluorine, strontium and some others . One of contemporary tools to reduce the ecotoxicity of polluted soils and soil-PG mixtures is an application of humic substances (HS) . The objective of this study was to evaluate the detoxifying ability of a number of humates towards PG applied to model soil mixtures .Model soil (MS) contained (wt, %) 20% of kaoline, 10% of peat and 70% of sand with particle size 0,2-0,4 mm (ISO 11268-1) . PG was carefully mixed with MS at concentration 3 .3 and 7 .5 wt, % . Humates from peat - Pe-FlexK, Pe-EcoK, coal - BC-EnK, BC-HumNa and lignosulphonate - OW-LhK introduced into the MS in the form of an aqueous suspension (distilled water) to achieve a concentration in soils 0 .005 and 0 .020 wt, % . The ecotoxicity was evaluated in water extracts using three species of testorganisms from different taxonomic groups: microalgae Scenedesmus quadricauda (decrease of cells population growth, 72h), crustaceans Daphnia magna (mortality, 96h), and higher plants Sinapis alba (decrease of root elongation, 120h) . Toxicometric parameters (EC50- the median PG concentration that caused a 50% test-reaction reduction, and NOEL - no observed effect level - the PG concentration that caused test-reaction reduction below the toxic level) and detoxification indexes D were calculated .Analyses of average detoxification indexes DAV (averaged over three test-organisms) showed that influence of humates depended both on PG concentration and humates’ nature . Thus, application of PG at concentration 7 .5 wt, % was toxic for all the test-cultures at all treatments and humates were not able to decrease the toxicity . At lower rate of PG (3 .3 wt, %) some humates decreased the toxicity (DAV is 0 .5-0 .8), whether other did not . Among all humates tested the highest detoxifying ability was observed for two samples: Pe-FlexK from peat and BC-EnK from coal . For these humates EC50 and NOEL values increased in 1 .3-1 .8 times for S. Quadricauda, in 1 .1-1 .4 times for D. Magna, in 1 .6-2 times for S. alba for 0 .005 wt, % humates content . Acknowledgement - This research was supported by Russian Federal Science (GK 02 .740 .11 .0693), Russian Foundation of Basic Research (project 10-04-01681.

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