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Dynamic release and transformation of metallic copper colloids in flooded paddy soil: Role of soil reducible sulfate and temperature.
Journal of Hazardous Materials ( IF 13.6 ) Pub Date : 2020-07-12 , DOI: 10.1016/j.jhazmat.2020.123462
Hang Xu 1 , Bing Xia 2 , Erkai He 3 , Rongliang Qiu 2 , Willie J G M Peijnenburg 4 , Hao Qiu 3 , Ling Zhao 1 , Xiaoyun Xu 1 , Xinde Cao 1
Affiliation  

Mobile metal Cu colloids can be formed in periodically flooded paddy soils, potentially aggravating the risks to rice cultivated in these soils. Here, we investigated the formation and fate of Cu colloids in flooded soil as influenced by soil reducible sulfate and temperature. In microcosms with different initial sulfate availability (1.30, 5.34, or 7.38 mmol/kg), we found the treatments with higher sulfate concentrations showed the greater and faster release of metal colloids. Sulfate reduction resulted in the transformation of copper in the colloids from Cu(0) to CuxS, and the percentage of CuxS in the colloid phase increased with increasing sulfate content according to the Cu K-edge EXAFS spectra. The batch experiments incubated at 5, 25 or 35 °C proved that high temperature enhanced the microbial activity and released more Cu colloids during flooding. The colloid formation was delayed at low temperature but persisted longer in the soil, which led to greater particle average size because of slow growth and uniform agglomeration. Low temperature appeared to only influence the formation and growth but not the speciation of Cu colloids. Our results highlight the importance of soil reducible sulfate and temperature in mediating the dynamics of colloidal metals in flooded soil.



中文翻译:

淹水水稻土中金属铜胶体的动态释放和转化:土壤可还原硫酸盐和温度的作用。

可在定期淹没的稻田土壤中形成可移动的金属Cu胶体,可能加剧在这些土壤中种植水稻的风险。在这里,我们研究了受土壤可还原硫酸盐和温度影响的淹水土壤中铜胶体的形成和命运。在具有不同初始硫酸盐可利用性(1.30、5.34或7.38 mmol / kg)的微观世界中,我们发现硫酸盐浓度较高的处理表明金属胶体的释放更快。硫酸盐还原导致胶体中的铜从Cu(0)转变为Cu x S,并且随着硫酸铜含量的增加,胶体相中Cu x S的百分比随Cu K的增加而增加边缘EXAFS光谱。在5、25或35°C下温育的分批实验证明,高温可提高淹没过程中的微生物活性并释放更多的Cu胶体。胶体的形成在低温下被延迟,但在土壤中持续更长的时间,由于生长缓慢和均匀的团聚,导致平均粒径更大。低温似乎只影响Cu胶体的形成和生长,而不影响其形态。我们的结果突出了土壤可还原的硫酸盐和温度在介导淹没土壤中胶态金属动力学中的重要性。

更新日期:2020-07-16
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