Environmental Futures Centre, Griffith University, Gold Coast Campus, QLD 4222, Australia.
Environ Sci Technol. 2012 Feb 21;46(4):2267-75. doi: 10.1021/es203674n. Epub 2012 Feb 6.
Aluminum is acutely toxic, and elevated concentrations of dissolved Al can have detrimental effects on both terrestrial and aquatic ecosystems. Robust analytical methods that can determine environmentally relevant Al fractions accurately and efficiently are required by the environmental monitoring community. A simple, robust passive sampling method, the diffusive gradients in thin films (DGT) technique, was evaluated for the measurement of dissolved Al species in freshwater and marine water using either Chelex-100 or Metsorb (a titanium dioxide-based binding agent) as the adsorbent. Mass vs time DGT deployments at pH 5.05 (Al(3+) and Al(OH)(2+) dominate) and 8.35 (Al(OH)(4)(-) dominates) demonstrated linear uptake of Al (R(2) = 0.989 and 0.988, respectively) for Metsorb. Similar deployments of Chelex-DGT showed linear uptake at pH 5.05 (R(2) = 0.994); however, at pH 8.35 the mass of Al accumulated was 40-70% lower than predicted, suggesting that Chelex-100 is not suitable for Al measurements at high pH. The Metsorb-DGT measurement was independent of pH (5.0-8.5) and ionic strength (0.001-0.7 mol L(-1) NaNO(3)), whereas the Chelex-DGT measurement was only independent of ionic strength at pH 5.0. At pH 8.4, increasing ionic strength led to considerable underestimation (up to 67%) of Al concentration. Deployments of Metsorb-DGT (up to 4 days) in synthetic freshwater (pH range 5.4-8.1) and synthetic seawater (pH 8.15) resulted in linear mass uptakes, and the concentration measured by DGT agreed well with solution concentrations. Conversely, deployment of Chelex-DGT in synthetic seawater and freshwater (pH ≥7.7 Al(OH)(4)(-) dominant species) resulted in a decrease in accumulated mass with increasing deployment time. In situ field evaluations in fresh, estuarine, and marine waters confirmed that Metsorb-DGT was more accurate than Chelex-DGT for the measurement of dissolved Al in typical environmental waters.
铝是一种剧毒物质，高浓度的溶解态铝会对陆地和水生生态系统造成有害影响。环境监测界需要能够准确、高效地测定环境相关铝形态的强大分析方法。本研究评估了使用 Chelex-100 或 Metsorb（一种基于二氧化钛的结合剂）作为吸附剂的扩散梯度薄膜（DGT）技术在淡水和海水中测定溶解态铝形态的方法。在 pH 值为 5.05（Al(3+)和 Al(OH)(2+)占主导）和 8.35（Al(OH)(4)(-)占主导）时，质量随时间的 DGT 部署表明 Metsorb 对铝的吸收呈线性（分别为 R(2) = 0.989 和 0.988）。在 pH 值为 5.05 时，Chelex-DGT 的类似部署也表现出线性吸收（R(2) = 0.994）；然而，在 pH 值为 8.35 时，积累的铝量比预测值低 40-70%，表明 Chelex-100 不适合在高 pH 值下进行铝测量。Metsorb-DGT 测量值不受 pH 值（5.0-8.5）和离子强度（0.001-0.7 mol L(-1) NaNO(3)）的影响，而 Chelex-DGT 测量值仅在 pH 值为 5.0 时不受离子强度的影响。在 pH 值为 8.4 时，离子强度的增加导致铝浓度的严重低估（高达 67%）。在合成淡水（pH 值范围为 5.4-8.1）和合成海水（pH 值为 8.15）中，Metsorb-DGT 的部署时间长达 4 天，导致质量呈线性吸收，并且 DGT 测量的浓度与溶液浓度吻合良好。相反，Chelex-DGT 在合成海水中和淡水（pH ≥7.7，Al(OH)(4)(-)占主导）中的部署会导致随部署时间的增加而积累的质量减少。在淡水、河口和海水中的现场评估证实，Metsorb-DGT 比 Chelex-DGT 更适合测定典型环境水中的溶解态铝。
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