School of Environment Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia; Marine Ecology Research Centre, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia.
School of Environment Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia; Marine Ecology Research Centre, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia.
Sci Total Environ. 2017 Mar 1;581-582:782-793. doi: 10.1016/j.scitotenv.2017.01.009. Epub 2017 Jan 5.
Bio-accessibility and bioavailability of arsenic (As) in historically As-contaminated soils (cattle tick pesticide), and pristine soils were assessed using 3 different approaches. These approaches included human bio-accessibility using an extraction test replicating gastric conditions (in vitro physiologically-based extraction test); an operationally defined bioaccessibility extraction test - 1.0M HCl extraction; and a live organism bioaccumulation test using earthworms. A sequential extraction procedure revealed the soil As-pool that controls bio-accessibility and bioaccumulation of As. Findings show that As is strongly bound to historically contaminated soil with a lower degree of As bio-accessibility (<15%) and bioaccumulation (<9%) compared with freshly contaminated soil. Key to these lower degrees of bio-accessibility and bioaccumulation is the greater fraction of As associated with crystalline Fe/Al oxy-hydroxide and residual phases. The high bio-accessibility and bioaccumulation of freshly sorbed As in pristine soils were from the exchangeable and specifically sorbed As fractions. Arsenic bioaccumulation in earthworms correlates strongly with both the human bio-accessible, and the operationally defined bioavailable fractions. Hence, results suggest that indirect As bioavailability measures, such as accumulation by earthworm, can be used as complementary lines of evidence to reinforce site-wide trends in the bio-accessibility using in vitro physiologically-based extractions and/or operationally defined extraction test. Such detailed knowledge is useful for successful reclamation and management of the As contaminated soils.
采用 3 种不同方法评估了历史上受砷（As）污染的土壤（牛蜱杀虫剂）和原始土壤中的砷生物可给性和生物利用度。这些方法包括使用模拟胃条件的提取试验进行人体生物可给性（体外基于生理学的提取试验）；可操作定义的生物可给性提取试验-1.0M HCl 提取；以及使用蚯蚓进行活体生物累积试验。连续提取程序揭示了控制 As 生物可给性和生物累积的土壤 As 库。研究结果表明，与新污染土壤相比，As 与历史上受污染的土壤结合紧密，生物可给性（<15%）和生物累积（<9%）较低。这些较低的生物可给性和生物累积的关键是与结晶 Fe/Al 水合氧化物和残余物相关的 As 比例较大。原始土壤中新鲜吸附的 As 具有较高的生物可给性和生物累积性，这是由于可交换和特定吸附的 As 分数。蚯蚓体内的砷生物累积与人体生物可给性和可操作定义的生物有效分数密切相关。因此，结果表明，间接的 As 生物有效性测量，如通过蚯蚓积累，可以作为补充证据，以支持使用体外基于生理学的提取和/或可操作定义的提取试验来评估生物可给性的全区域趋势。这种详细的知识对于成功开垦和管理受 As 污染的土壤非常有用。
