Speciation of selenium and organotin compounds in sewage sludge applied to land

Selenium in agriculture, food, and nutrition

“…Only >1 % of elemental and <2 % of metal selenide was solubilized by 0.1 M NaOH extraction, indicating its high selectivity for organically associated Se [61]. In sewage sludges, which are low in residual minerals and extremely high in organic carbon, total Se could be found in the NaOH -extract [56]. In wetlands, organic forms of Se are subject to greater bioavailability and bioaccumulate more rapidly than selenite and selenate [60].…”

“…Extraction of soils and sediments with neutral phosphate or citrate/phosphate buffer solutions yields an exchangeable fraction, which can be investigated for further speciation in solution [54][55][56][57][58]. After removal of solubles and exchangeables, oxalate pH 3 selectively extracts selenite bound to iron hydroxides, which is the main fraction in acid soils.…”

Comportement de radionucléides (Cs, I, Sr, Se, Tc) dans le sol : proposition de valeurs de Kd par défaut

“…Des extractions ont été utilisées pour estimer la disponibilité du sélénium (Mao et Xing, 1999 ;Sharmasarkar et Vance, 2002). Les méthodes d'identification des degrés d'oxydation du sélénium restent cependant encore limitées (Casiot et al, 1998 ;Heninger et al, 1998 ;Yamada et al, 1999) et actuellement, il n'y a pas de méthode directe de spéciation du sélénium dans le sol. La forme sélénite semble dominer dans la plupart des sols « moyens » i.e., en environnement aérobie légèrement oxydant ou modérément réducteur (Frankenberger et Karlson, 1994).…”

Optimisation using experimental designs of the sample pretreatment: application to the control of the organotins in sewage sludge by GC-FPD

“…The variation field [high (+1) and low (-1) levels] of the different factors was defined by reviewing the contribution of each variable of the acidic extraction and ethylation, in order to plan the initial design. Considering the literature about the extraction of environmental solid matrices 1,4,[7][8][9][10][21][22][23][24][25][26] and according to our knowledge of the analytical process, 13,20 the following parameters of the sample pretreatment were examined: Sample mass. The processes related to sludge extraction and presented by different authors involve masses ranging from 1 to 20 g. 1,4,8,10 Nevertheless, it was previously found in our laboratory that 2 g of wet sample was the maximum mass for a quantitative extraction, due to the stirring efficiency.…”

“…[2][3][4][5][6][7][8][9][10] This pollution is a real problem in regard to the frequent agricultural use of the sludge and to the ecotoxicological impacts of these compounds. [11][12][13] Consequently, it appeared necessary to control their concentration by means of accurate and sensitive analytical methods.…”