薄膜扩散梯度技术测量砷的影响因素及其应用

研究了水体中常见无机阴离子和腐植酸对以氧化锆为固定膜的新型薄膜扩散梯度技术(Zr-oxide DGT)测量砷(As)的影响及其在自然地表水体中的应用.结果表明,短期(16h)暴露,SO_4~(2-)无影响,而HCO_3~-、Cl~-、SiO_3~(2-)和腐植酸有一定的影响,其忍耐的最高浓度值分别为360mg/L、45g/L、100mg/L和36mg/L.1~4d暴露期间,37~148mg/L的HCO_3~-、1.44~2.88g/L的SO_4~(2-)、12~24g/L的Cl~-、8~24mg/L的SiO_3~(2-)和3~9mg/L的腐植酸均无影响,而高浓度的HCO_3~-(370mg/L)、SO_4~(2-)(8.64g/L)、Cl~-(72g/L)和腐植酸(27mg/L)3~4d以及SiO_3~(2-)(72mg/L)2~4d的存在明显降低该技术对As的吸收富集,并对As(Ⅲ)的作用更大.将Zr-oxide DGT技术应用于南京市地表水体,并与传统的主动监测方法进行比较,发现利用Zr-oxide DGT技术测得的溶解态As浓度与传统的主动采样技术测定浓度一致.

Environmental influences on the measurement of dissolved arsenic using Zr-oxide DGT

Influences of environmental factors on the measurement of dissolved arsenic (As) using Zr-oxide diffusive gradient in thin films technique (Zr-oxide DGT) were systematically investigated in the laboratory, and this technique was applied for in situ determination of dissolved As in natural water. After 16-d exposure of numerous inorganic anions, the presence of SO₄^2- had no influence on the measurement of As using Zr-oxide DGT, while HCO₃^-, Cl^-, SiO₃^2- and humic acid had negative effects, with the largest tolerant concentrations of 360mg/L, 45g/L, 100mg/L and 36mg/L, respectively. The dynamical uptake showed that there were no influences of HCO₃^-(37~148mg/L), SO₄^2-(1.44~2.88g/L), Cl^-(12~24g/L), SiO₃^2-(8~24mg/L) and humic acid (3~9mg/L) with the exposure time span from 1 to 4d, while the uptake of As to Zr-oxide DGT, particularly As (III), were inhibited by high concentrations of HCO₃^-(370mg/L), SO₄^2-(8.64g/L), Cl^-(72g/L) and humic acid (27mg/L) at the exposure time of 3~4d, and SiO₃^2-(72mg/L) at the exposure time of 2~4d. The Zr-oxide DGT sampling technique was applied to water in Nanjing City in comparison with the conventional monitoring technique. The DGT-measured concentrations of dissolved As were in line with those by the conventional monitoring technique.