Arco-Lázaro Elena, Agudo Inés, Clemente Rafael, Bernal M Pilar
Department of Soil and Water Conservation and Organic Waste Management, Centro de Edafología y Biología Aplicada del Segura-CSIC, Campus Universitario de Espinardo, 30100 Murcia, Spain.
Department of Soil and Water Conservation and Organic Waste Management, Centro de Edafología y Biología Aplicada del Segura-CSIC, Campus Universitario de Espinardo, 30100 Murcia, Spain.
Environ Pollut. 2016 Sep;216:71-79. doi: 10.1016/j.envpol.2016.05.054. Epub 2016 May 26.
High total and bioavailable concentrations of As in soils represent a potential risk for groundwater contamination and entry in the food chain. The use of organic amendments in the remediation of As-contaminated soils has been found to produce distinct effects on the solubility of As in the soil. Therefore, knowledge about As adsorption-desorption processes that govern its solubility in soil is of relevance in order to predict the behaviour of this element during these processes. In this paper, the objective was to determine As adsorption and desorption in four different soils, with and without compost addition, and also in competition with phosphate, through the determination of sorption isotherms. Batch experiments were carried out using three soils affected differently by previous mining activity of the Sierra Minera of La Unión-Cartagena (SE Spain) and an agricultural soil from Segovia province (central Spain). Adsorption was higher in the mining soils (and highest in the acidic one) than in the agricultural soils, although the latter were not affected negatively by organic matter or phosphate competition for sorption sites. The results show that As adsorption in most soils, both with and without compost, fitted better a multimolecular layer model (Freundlich), whereas As adsorption in competition with P fitted a monolayer model (Langmuir). Moreover, the use of compost and phosphate reduced the adsorption of As in the mining soils, while in the agricultural soils compost increased their low adsorption capacity. Therefore, the use of compost can be a good option to favour As immobilisation in soils of low adsorption, but knowledge of the soil composition will be crucial to predict the effects of organic amendments on As solubility in soils and its associated environmental risk.
土壤中砷的总浓度和生物可利用浓度较高，对地下水污染和进入食物链构成潜在风险。研究发现，在修复受砷污染的土壤时使用有机改良剂会对土壤中砷的溶解度产生不同影响。因此，了解控制砷在土壤中溶解度的吸附 - 解吸过程对于预测该元素在这些过程中的行为具有重要意义。本文的目的是通过测定吸附等温线，确定四种不同土壤（添加和不添加堆肥）以及在与磷酸盐竞争的情况下砷的吸附和解吸情况。使用了三种受西班牙东南部拉乌尼翁 - 卡塔赫纳矿业山脉先前采矿活动影响程度不同的土壤以及西班牙中部塞哥维亚省的一种农业土壤进行批量实验。采矿土壤中的吸附率高于农业土壤（酸性采矿土壤中的吸附率最高），尽管后者并未因有机质或磷酸盐对吸附位点的竞争而受到负面影响。结果表明，大多数土壤（无论是否添加堆肥）中的砷吸附更符合多分子层模型（弗伦德利希模型），而与磷竞争时的砷吸附符合单分子层模型（朗缪尔模型）。此外，堆肥和磷酸盐的使用降低了采矿土壤中砷的吸附，而在农业土壤中，堆肥提高了它们较低的吸附能力。因此，使用堆肥可能是促进低吸附土壤中砷固定的一个好选择，但了解土壤成分对于预测有机改良剂对土壤中砷溶解度及其相关环境风险的影响至关重要。
