Twiss Michael R, Moffett James W
Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Massachusetts 02543, USA.
Environ Sci Technol. 2002 Mar 1;36(5):1061-8. doi: 10.1021/es0016553.
The diffusion gradient in thin-film hydrogel (DGT) probe is a promising tool for metal speciation work. Based on a passive sampling principle, it provides the potential for large data sets in complex regimes. DGT probes were deployed in waters characterized independently using competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV). The CLE-ACSV used benzoyl acetone as the competitive ligand in discrete water samples collected during the deployment of the DGT probes. The DGT probes used a 15% polyacrylamide/0.4% bis-acrylamide cross-linker hydrogel and a Na-form of Chelex-100 to complex metal that fluxed into the probe through the hydrogel. Probes were deployed in locations characterized by the degree of pollution impact: the relatively pristine Vineyard Sound, MA, [Cu]total approximately 6 nM, small seasonally active harbors on Cape Cod, MA, [Cu]total = 12-64 nM, as well as a large polluted estuary, the Elizabeth River, VA, [Cu]total = 44-58 nM, and a large polluted port, San Diego Harbor, CA, [Cu]total = 23-103 nM. This is the first study where DGT probes have been compared with an independent speciation technique in marine systems and used to establish the diffusion coefficient of Cu-complexing ligands in situ. Results showed that the probes produced highly precise data sets, with substantial differences in copper accumulation between contaminated and pristine waters. Comparison of DGT results with CLE-CSV indicate that at least 10-35% of the organically complexed copper derived by CLE-ACSV measurements was DGT-labile. Diffusion coefficients (corrected to 25 degrees C) of organically complexed DGT-labile Cu through the hydrogel ranged from 0.77 x 10(-6) cm2 s(-1) in Vineyard Sound to 2.16 x 10(-6) cm2 s(-1) in the Elizabeth River estuary. Accumulation rates of copper were substantially higher in contaminated waters than in pristine waters, suggesting that the probes in their current form may be useful as tracking tools to detect episodic sources of contamination.
薄膜水凝胶（DGT）探头中的扩散梯度是一种用于金属形态分析的很有前景的工具。基于被动采样原理，它为复杂环境下的大数据集提供了可能。DGT探头被部署在通过竞争配体交换 - 吸附阴极溶出伏安法（CLE - ACSV）独立表征的水体中。CLE - ACSV在DGT探头部署期间采集的离散水样中使用苯甲酰丙酮作为竞争配体。DGT探头使用15%的聚丙烯酰胺/0.4%的双丙烯酰胺交联剂水凝胶和钠型的Chelex - 100来络合通过水凝胶流入探头的金属。探头被部署在具有不同污染影响程度的地点：相对原始的马萨诸塞州葡萄园海湾，总铜含量约为6 nM；马萨诸塞州科德角季节性活跃的小港口，总铜含量 = 12 - 64 nM；以及一个大型污染河口，弗吉尼亚州伊丽莎白河，总铜含量 = 44 - 58 nM；还有一个大型污染港口，加利福尼亚州圣地亚哥港，总铜含量 = 23 - 103 nM。这是第一项在海洋系统中将DGT探头与独立的形态分析技术进行比较并用于原位确定铜络合配体扩散系数的研究。结果表明，探头产生了高度精确的数据集，污染水体和原始水体中的铜积累存在显著差异。DGT结果与CLE - CSV的比较表明，通过CLE - ACSV测量得出的有机络合铜中至少10 - 35%是DGT易变的。通过水凝胶的有机络合DGT易变铜的扩散系数（校正到25摄氏度）范围从葡萄园海湾的0.77×10⁻⁶ cm² s⁻¹到伊丽莎白河河口的2.16×10⁻⁶ cm² s⁻¹。污染水体中铜的积累速率显著高于原始水体，这表明当前形式的探头可能作为检测间歇性污染源的跟踪工具是有用的。
