College of Environmental Science and Engineering, Anhui Normal University, Wuhu, 241002, China.
Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, China.
Environ Sci Pollut Res Int. 2020 May;27(14):16646-16655. doi: 10.1007/s11356-020-08107-6. Epub 2020 Mar 4.
Diphenylarsinic acid (DPAA) is an emerging phenylarsenic compound derived from chemical warfare agents. It has been suggested that biostimulation of sulfate reduction decreases the concentrations of DPAA in soils. However, biostimulation often induces Fe(III) reduction which may affect the mobility and thereby the transformation of DPAA. Here, a soil incubation experiment was carried out to elucidate the impact of Fe(III) reduction on the mobilization and transformation of DPAA in a biostimulated Acrisol with the addition of sulfate and lactate. DPAA was significantly mobilized and then thionated in the sulfide soil (amended with sulfate and sodium lactate) compared with the anoxic soil (without addition of sulfate or sodium lactate). At the start of the incubation period, 41.8% of the total DPAA in sulfide soil was mobilized, likely by the addition of sodium lactate, and DPAA was then almost completely released into the solution after 2 weeks of incubation, likely due to Fe(III) reduction. The relatively low fraction of oxalate-extractable Fe in Acrisol, which contributes significantly to DPAA sorption and is more active and reduction-susceptible, may explain the observation that only < 40% of the Fe(III) (hydr)oxides were reduced when DPAA was completely released into the solution. A more rapid and final enhanced elimination of DPAA was observed in sulfide soil and the fraction of total DPAA decreased to 60.1 and 91.0%, respectively, at the end of the incubation in sulfide soil and anoxic soil. The difference appears to result from increased DPAA mobilization and sulfate reduction in sulfide soil. On the other hand, the formation of FeS precipitate, a product of Fe and sulfate reduction, may reduce the efficiency of DPAA thionation. Accordingly, the potentially contrasting effects of Fe(III) reduction on DPAA thionation need be considered when planning biostimulated sulfate reduction strategies for DPAA-contaminated soils.
二苯胂酸（DPAA）是一种新兴的苯胂化合物，来源于化学战剂。有研究表明，硫酸盐还原的生物刺激会降低土壤中 DPAA 的浓度。然而，生物刺激通常会诱导三价铁还原，这可能会影响 DPAA 的迁移性和转化。在这里，进行了一项土壤孵育实验，以阐明三价铁还原对添加硫酸盐和乳酸盐的生物刺激下 Acrisol 中 DPAA 迁移和转化的影响。与缺氧土壤（未添加硫酸盐或乳酸钠）相比，在添加了硫酸盐和乳酸钠的硫化物土壤（添加了硫酸盐和乳酸钠）中，DPAA 明显被迁移并随后被硫代化。在孵育期开始时，硫化物土壤中总 DPAA 的 41.8%被迁移，可能是由于添加了乳酸钠，并且在孵育 2 周后，DPAA 几乎完全释放到溶液中，可能是由于三价铁还原。Acrisol 中草酸盐可提取铁的相对较低分数对 DPAA 的吸附有重要贡献，并且更活跃且更易还原，这可能解释了只有当 DPAA 完全释放到溶液中时，只有<40%的三价铁（氢）氧化物被还原的观察结果。在硫化物土壤中观察到 DPAA 更快速和最终增强的消除，并且在硫化物土壤和缺氧土壤的孵育结束时，总 DPAA 的分数分别降低到 60.1%和 91.0%。这种差异似乎是由于硫化物土壤中 DPAA 的迁移和硫酸盐还原的增加所致。另一方面，FeS 沉淀的形成是铁和硫酸盐还原的产物，可能会降低 DPAA 硫代化的效率。因此，在规划 DPAA 污染土壤的生物刺激硫酸盐还原策略时，需要考虑三价铁还原对 DPAA 硫代化的潜在对比影响。
