Combining cross flow ultrafiltration and diffusion gradients in thin-films approaches to determine trace metal speciation in freshwaters
Combining cross flow ultrafiltration and diffusion gradients in thin-films approaches to determine trace metal speciation in freshwaters
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DOI：
10.1016/j.gca.2013.01.030
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发表时间：
2013-05
影响因子：
5
通讯作者：
Ruixia Liu;J. Lead;Hao Zhang
中科院分区：
文献类型：
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作者：
Ruixia Liu;J. Lead;Hao Zhang
错流超滤（CFUF）和薄膜扩散梯度（DGT）与开孔凝胶（OP）和限制孔凝胶（RP）被用来测量痕量金属形态在选定的英国淡水。以颗粒形式（>1微米）存在的金属比例变化很大，Pb为40-85%，Al为60-80%，Mn为7-56%，Cu为10-49%，Zn为0-55%，Cr为20 - 38%，Fe为20-30%，Co为6-25%，Cd为5-22%，Ni <7%。在胶体级分（2kDa-1μm）中，值在53-91%的Pb、33-55%的Al、21-55%的Cu、20-44%的Fe、34-36%的Cr、20-40%的Cd、7-28%的Co和Ni、2-32%的Zn和<8%的Mn之间变化。超滤部分（<2 kDa）中也观察到了很大的变化。这些结果表明，胶体确实影响的发生和传输的Al，Fe，Cr，Co，Ni，Cu，Zn，Cr和Pb金属在河流中，而无机或有机胶体没有发挥重要的控制在选定的淡水中的Mn的传输。在所有选定的沃茨中，DGT-OP测定的总不稳定金属占总物种的1.4-50%，其中Al、Fe、Co、Ni、Cu、Cd和Pb。这些金属总不稳定铅浓度最低的值小于1.4%，虽然这个值略有增加扣除颗粒分数后。在某些沃茨中，总Mn、Zn和Cr的大部分是DGT不稳定态，其中DGT不稳定态Mn占总溶解相的98-118%.在大多数情况下，DGT-RP测量的无机不稳定浓度低于总的不稳定金属浓度。通过CFUF和DGT技术的组合，在CFUF衍生的真正溶解相中的总的不稳定和无机不稳定金属物种的浓度测定在四个水样中。发现100%的超滤Mn物质是总DGT不稳定的。所有沃茨中Al、Fe、Co、Ni、Cu、Cd和Pb的总不稳定金属物种的比例均低于超滤组分的比例，在某些情况下Cr和Zn的比例也低于超滤组分的比例，表明存在大量的天然配位体，这些配位体具有较小的尺寸，可供金属形成动力学惰性物种或化学稳定的络合物。观察到的金属形态之间的差异和采样点内的金属的特性和水源的性质的差异有关。
Cross flow ultrafiltration (CFUF) and diffusive gradients in thin films (DGT) with open pore gel (OP) and restricted pore gel (RP) were used to measure trace metal speciation in selected UK freshwaters. The proportions of metals present in particulate forms (>1μm) varied widely between 40–85% Pb, 60–80% Al, 7–56% Mn, 10–49% Cu, 0–55% Zn, 20–38% Cr, 20–30% Fe, 6–25% Co, 5–22% Cd and <7% Ni. In the colloidal fraction (2kDa–1μm) values varied between 53–91% Pb, 33–55% Al, 21–55% Cu, 20–44% Fe, 34–36% Cr, 20–40% Cd, 7–28% Co and Ni, 2–32% Zn and <8% Mn. Wide variations were also observed in the ultrafiltered fraction (<2kDa). These results indicated that colloids indeed influenced the occurrence and transport of Al, Fe, Cr, Co, Ni, Cu, Zn, Cr and Pb metals in rivers, while inorganic or organic colloids did not exert an important control on Mn transport in the selected freshwaters. Of total species, total labile metal measured by DGT-OP accounted for 1.4–50% for Al, Fe, Co, Ni, Cu, Cd and Pb in all selected waters. Of these metals total labile Pb concentration was the lowest with value less than 1.4% although this value slightly increased after deducting particulate fractions. In some waters, a majority of total Mn, Zn and Cr is DGT labile, in which the DGT labile Mn fraction accounted for 98–118% of the total dissolved phase. In most cases, the inorganic labile concentration measured by DGT-RP was lower than the total labile metal concentration. By the combination of CFUF and DGT techniques, the concentrations of total labile and inorganic labile metal species in CFUF-derived truly dissolved phase were measured in four water samples. 100% of ultrafiltered Mn species was found to be total DGT labile. The proportions of total labile metal species were lower than those of ultrafiltered fraction for Al, Fe, Co, Ni, Cu, Cd and Pb in all selected waters, and Cr and Zn in some cases, indicating a large amount of natural complexing ligands with smaller size for the metals to form kinetically inert species or thermodynamically stable complexes. Observed discrepancies in metal speciation between metals and within sampling sites were related to the differences in the characteristics of the metals and the nature of water sources.