Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China.
Environ Geochem Health. 2018 Oct;40(5):1919-1929. doi: 10.1007/s10653-017-9968-8. Epub 2017 May 5.
Diffusive gradients in thin films technique (DGT) is a dynamically passive sampling technique which has been applied increasingly to the environmental monitoring field. In the preliminary period, the DGT with zirconium hydroxide-silver iodide as the binding phase (ZrO-AgI DGT) has been developed for the determination of sulfide (S(II)). On this basis, this paper developed its determination method for inorganic arsenite (As(III)) to further realize the simultaneous and high-resolution measurements of labile inorganic As and S(II) in sediments. ZrO-AgI binding gel had a strong ability in adsorbing and fixing As(III), showing a linear increase in the initial 12.5 min. After saturation of S(II) on ZrO-AgI binding gel, the adsorption rate and adsorption capacity of As(III) reduced by 8 and 14%, respectively. A stable elution rate (89.1 ± 2.2%) was obtained by extraction of As(III) on the binding gel using a mixture solution of 1.0 M NaOH and 1.0 M HO (1:1). The DGT capacity of As(III) determined by the ZrO-AgI DGT was 23.6 μg cm. DGT uptakes of As(III) were independent of pH (4.0-9.0) and ionic strength (0.01-100 mM), and they did not interfere with each other during the uptake process. Simultaneous measurements of labile As and S(II) in four sediment cores of Taihu Lake (China) with ZrO-AgI DGT showed that they had similarly vertical distributions in the top 16-mm layer in one core and in the whole profile up to the 35 mm depth in two cores. It likely reflected a simultaneous release of As and S(II) in sediments by synchronous reduction of As-hosted oxidized iron and sulfate, respectively. The simultaneous decreases of labile As and S(II) from their co-precipitation (e.g., AsS) were not obvious in deeper sediment layer through the measurement with ZrO-AgI DGT.
扩散梯度薄膜技术（DGT）是一种动态被动采样技术，已越来越多地应用于环境监测领域。在初步阶段，开发了以氢氧化锆-碘化银为结合相的 DGT（ZrO-AgI DGT），用于测定硫化物（S(II)）。在此基础上，本文建立了其测定无机亚砷酸盐（As(III)）的方法，以进一步实现沉积物中可利用的无机砷和 S(II)的同时、高分辨率测定。ZrO-AgI 结合凝胶对 As(III)具有很强的吸附固定能力，在前 12.5 分钟内呈线性增加。当 ZrO-AgI 结合凝胶上的 S(II)饱和后，As(III)的吸附速率和吸附容量分别降低了 8%和 14%。采用 1.0 M NaOH 和 1.0 M HO（1:1）混合溶液从结合凝胶上萃取 As(III)，可获得稳定的洗脱率（89.1±2.2%）。用 ZrO-AgI DGT 测定的 As(III)的 DGT 容量为 23.6μgcm。ZrO-AgI DGT 对 As(III)的 DGT 摄取不受 pH（4.0-9.0）和离子强度（0.01-100 mM）的影响，并且在摄取过程中彼此之间没有干扰。用 ZrO-AgI DGT 对太湖四个沉积物岩芯中的可利用砷和 S(II)进行同步测量，结果表明，在一个岩芯的 16mm 表层中以及两个岩芯的整个剖面直至 35mm 深度中，它们具有相似的垂直分布。这可能反映了沉积物中 As 和 S(II)的同步释放，分别是由于 As 负载的氧化铁和硫酸盐的同步还原。通过 ZrO-AgI DGT 测量，在更深的沉积物层中，可利用的 As 和 S(II)从共沉淀（例如 AsS）中的同时减少并不明显。
