School of Chemistry, University of Wollongong, NSW 2522, Australia.
Environ Sci Process Impacts. 2018 May 23;20(5):833-844. doi: 10.1039/c8em00057c.
Elevated concentrations of As and Sb impact environmental quality and human health. In this study total and bioavailable As and Sb were measured from recently and historically contaminated soils and the phytotoxicity of these soils was evaluated with Ipomoea aquatica (35-d exposure from germination) using biomass, length of plant tissues and photosynthetic efficiency. As and Sb were both present within the soil (co-contaminated). The bioavailable As and Sb in soils were determined by a Sequential Extraction Procedure (SEP) and compared to total soil concentrations and bioaccumulation in the edible parts of I. aquatica. For both As and Sb, bioavailable concentrations increased proportionally with the total soil concentrations and greater bioavailability in recently contaminated soil was observed. Tissue dry mass and length drastically reduced with increasing total and SEP-bioavailable As and Sb soil concentrations. The total soil concentration was a less sensitive measure of the phytotoxicity of As and Sb than the bioavailable fraction. Shoot length was inhibited by 50% (EC50) at bioavailable As concentrations of 80-96 mg kg-1 in both recently and historically contaminated soils; however, bioavailable Sb EC50 for shoot length was achieved at lower bioavailable concentrations, 96 (42-219) and 12 (7-19) mg kg-1 in recently contaminated soils and historically contaminated soils, respectively. Shoot biomass was inhibited by 50% (EC50) at bioavailable As concentrations of 11 (4-30) and 49 (37-65) mg kg-1 in recently and historically contaminated soils, respectively whereas this occurred at much lower bioavailable Sb concentrations, 2-5 mg kg-1 in both recently and historically contaminated soils. Aging is important in contaminated soils, it decreases the lability of As and Sb and hence their bioavailability to agricultural plants, thus posing a lower risk of exposure of these metalloids to humans through agricultural plants grown in contaminated soils.
砷（As）和锑（Sb）浓度升高会影响环境质量和人类健康。本研究测定了近期和历史上受污染土壤中的总砷和总锑以及生物可利用砷和锑的浓度，并采用空心菜（35 天的萌发期暴露）评估了这些土壤的植物毒性，通过生物量、植物组织长度和光合效率来评价。土壤中同时存在砷和锑（共污染）。通过顺序提取程序（SEP）测定土壤中的生物可利用砷和锑，并将其与空心菜可食用部分中的土壤总砷和锑浓度以及生物累积进行比较。对于砷和锑，生物可利用浓度均与土壤总浓度呈比例增加，并且在近期污染土壤中观察到更高的生物可利用性。随着土壤中总砷和 SEP-生物可利用砷和锑浓度的增加，组织干质量和长度急剧减少。与生物可利用部分相比，土壤总浓度是砷和锑植物毒性的一种不太敏感的衡量标准。在近期和历史上受污染的土壤中，生物可利用砷浓度分别为 80-96mgkg-1 时，就会抑制 shoot 长度（EC50）的 50%；然而，生物可利用 Sb 对 shoot 长度的 EC50 则在较低的生物可利用浓度下实现，分别为 96（42-219）和 12（7-19）mgkg-1，在近期和历史上受污染的土壤中。在近期和历史上受污染的土壤中，生物可利用砷浓度分别为 11（4-30）和 49（37-65）mgkg-1 时，抑制 shoot 生物量（EC50）的 50%；而在近期和历史上受污染的土壤中，这一情况则发生在低得多的生物可利用 Sb 浓度下，分别为 2-5mgkg-1。老化在污染土壤中很重要，它降低了砷和锑的活性，从而降低了它们对农业植物的生物可利用性，因此通过在受污染土壤中种植的农作物，人类接触这些类金属的风险较低。
