State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Shanghai Waterway Engineering Design and Consulting Co., Ltd., Shanghai 200120, China.
Chemosphere. 2019 May;223:108-116. doi: 10.1016/j.chemosphere.2019.02.013. Epub 2019 Feb 5.
Differences in trophic status can lead to different water quality and sediment geochemistry characteristics, influencing antimony (Sb) mobility in sediments and its release into the water column. In this study, seasonal sampling was conducted in algal- and macrophyte-dominated zones of Lake Taihu, China. High-resolution dialysis (HR-Peeper) and diffusive gradients in thin films (DGT) techniques were used to measure soluble Sb and DGT-labile Sb in the sediment-water profiles at a 4 mm vertical resolution. Results showed that total Sb in sediments from the two zones were on average 3.50 mg/kg and 3.21 mg/kg in the algal- and macrophyte-dominated zones, respectively, with the residual fraction being 96.3% and 95.4% of the total Sb contents in the two zones. In winter, soluble Sb concentrations in both zones increased. This was probably due to the oxidation of Sb(III) to Sb(V) by Mn and Fe oxides. In summer and autumn, soluble Sb concentrations in the algal-dominated region remained low. This is attributed to the dominance of insoluble Sb(III) in sediments under anoxic conditions under eutrophic environments. In contrast, soluble Sb concentrations in the macrophyte-dominated zone were significantly high in summer and were 4.15-times higher than limits set by the World Health Organization (WHO). This likely resulted from the photochemical and rhizospheric oxidation of insoluble Sb(III) compounds. It is suggested that Sb contamination in the sediment-water system of the macrophyte-dominated zone deserves additional attention.
营养状态的差异会导致水质和沉积物地球化学特征的不同，从而影响沉积物中锑 (Sb) 的迁移及其向水相的释放。本研究在中国太湖的藻类和大型植物优势区进行了季节性采样。采用高分辨率透析（HR-Peeper）和扩散梯度薄膜（DGT）技术，以 4mm 的垂直分辨率测量了沉积物-水剖面中可溶性 Sb 和 DGT-不稳定 Sb。结果表明，两个区域沉积物中的总 Sb 平均含量分别为藻类优势区的 3.50mg/kg 和大型植物优势区的 3.21mg/kg，其中残余态 Sb 分别占两个区域总 Sb 含量的 96.3%和 95.4%。在冬季，两个区域的可溶性 Sb 浓度均升高。这可能是由于 Mn 和 Fe 氧化物将 Sb(III)氧化为 Sb(V)。在夏季和秋季，藻类优势区的可溶性 Sb 浓度保持较低水平。这归因于在富营养环境下缺氧条件下，沉积物中不溶性 Sb(III)占主导地位。相比之下，在大型植物优势区，可溶性 Sb 浓度在夏季显著升高，是世界卫生组织（WHO）设定限值的 4.15 倍。这可能是由于不溶性 Sb(III)化合物的光化学和根际氧化作用所致。因此，大型植物优势区的沉积物-水系统中的 Sb 污染值得进一步关注。
