University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water- and Waste-Management, Laboratory of Soil- and Groundwater-Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany; King Abdulaziz University, Faculty of Meteorology, Environment, and Arid Land Agriculture, Department of Arid Land Agriculture, Jeddah 21589, Saudi Arabia; International Research Centre of Nanotechnology for Himalayan Sustainability (IRCNHS), Shoolini University, Solan, 173212, Himachal Pradesh, India.
Department of Agricultural Chemistry, National Taiwan University, Taipei 10617, Taiwan.
Sci Total Environ. 2022 Dec 1;850:158087. doi: 10.1016/j.scitotenv.2022.158087. Epub 2022 Aug 15.
The release dynamics and mobilization of geogenic Ni, Co, and Cr in serpentine paddy soils under fluctuating redox conditions have not yet been well studied. Here we investigated the release dynamics of Cr, Co, and Ni and controlling factors (e.g., Fe, Mn, Mg, Cl, PO, SO, and dissolved organic carbon (DOC)) in a geogenic-contaminated serpentine soil under wide range of redox potential (E) changes. The effects of re-oxidation process have been also investigated. The soil was incubated for 28 days and E was controlled from oxidation (+200 mV) to reduction (-200 mV) and re-oxidation (+240 mV) using a microcosm setup in duplicates. The slurry pH increased, along with decreasing E. The average concentration of dissolved Co (17.1-23.6 μg L) decreased under low E/high pH and vice versa. The average concentration of dissolved Cr decreased sharply from 624 μg L to 54.4 μg L with decreasing E from +200 mV to 0 mV and the associated increase of pH from 7.8 to 8.5; then, it was constant around 24.5 μg L. Concentration of dissolved Ni was lower (73.5-84.6 μg L) under high E at the first week of incubation; then, increased to 108.5 μg L under low E (-200 mV); thereafter, increased more at the end up to 124.5 μg L at high E (+240 mV), because of the pH decrease. A factor analysis identified that Cr and Co formed one group with Mn and Mg, while Ni was clustered together with Cl, DOC, and SO. This indicates that the redox-induced release dynamic of Cr and Co was mainly governed by MnMg compounds, while the release of Ni was mainly affected by the aliphatic compounds of DOC and the redox chemistry of chlorides and sulfur in this soil. The re-oxidation increased the mobilization of Ni and Co and did not affect the release of Cr. These findings suggest that the redox-induced mobilization of geogenic Co, Ni, and Cr from soil to water in serpentine rice soils should be considered due to the high solubility and thus the associated bioavailability and potential environmental and human health risks, when such metal-enriched soils will be used for agricultural flood-dry cycle systems.
在波动的氧化还原条件下，蛇纹石稻田中地球成因的镍、钴和铬的释放动态和迁移尚未得到很好的研究。在这里，我们研究了在大范围氧化还原电位 (E) 变化下，一种地球成因污染的蛇纹石土壤中铬、钴和镍的释放动态及其控制因素（例如铁、锰、镁、氯、磷、硫和溶解有机碳 (DOC)）。还研究了再氧化过程的影响。将土壤在微宇宙装置中孵育 28 天，并使用微宇宙装置将 E 从氧化 (+200 mV) 控制到还原 (-200 mV) 和再氧化 (+240 mV)，重复两次。随着 E 的降低，浆液 pH 值升高。在低 E/高 pH 值条件下，溶解钴的平均浓度（17.1-23.6μg/L）降低，反之亦然。随着 E 从+200 mV 降低到 0 mV 和 pH 值从 7.8 增加到 8.5，溶解铬的平均浓度从 624μg/L 急剧下降到 54.4μg/L；然后，当 E 再次升高到+240 mV 时，它在 24.5μg/L 左右保持稳定。在孵育的第一周，高 E 下的溶解镍浓度较低（73.5-84.6μg/L）；然后，在低 E（-200 mV）下增加到 108.5μg/L；此后，在高 E（+240 mV）下，在结束时增加到 124.5μg/L，因为 pH 值降低。因子分析表明，Cr 和 Co 与 Mn 和 Mg 形成一组，而 Ni 与 Cl、DOC 和 SO 聚类。这表明，Cr 和 Co 的氧化还原诱导释放动态主要受 MnMg 化合物控制，而 Ni 的释放主要受土壤中 DOC 的脂肪族化合物和氯化物和硫的氧化还原化学的影响。再氧化增加了 Ni 和 Co 的迁移，而不影响 Cr 的释放。这些发现表明，在这种富含金属的土壤将用于农业干湿循环系统时，应考虑蛇纹石稻田中地球成因的 Co、Ni 和 Cr 从土壤到水的氧化还原诱导迁移，因为它们的高溶解度以及由此产生的生物利用度和潜在的环境和人类健康风险。
