Laboratorio de Ecoloxía Mariña, Universidade de Vigo, Campus Universitario, Vigo, Galicia, Spain.
Aquat Toxicol. 2010 Jan 31;96(2):90-102. doi: 10.1016/j.aquatox.2009.10.005. Epub 2009 Oct 9.
Water samples of contrasting origin, including natural seawater, two sediment elutriates and sewage-influenced seawater, were collected and obtained to examine the effect of the dissolved organic matter (DOM) present on metal bioavailability. The carbon content (DOC) and the optical properties (absorbance and fluorescence) of the coloured DOM fraction (CDOM) of these materials were determined. Cu and Pb complexation properties were measured by anodic stripping voltammetry (ASV) and the effect of DOM on Cu and Pb bioavailability was studied by means of the Paracentrotus lividus embryo-larval bioassay. Sediment elutriates and sewage-influenced water (1) were enriched 1.4-1.7 times in DOC; (2) absorbed and reemitted more light; and (3) presented higher Cu complexation capacities (L(Cu)) than the natural seawater used for their preparation. L(Cu) varied from 0.08 microM in natural seawater to 0.3 and 0.5 microM in sediment elutriates and sewage-influenced water, respectively. Differences in DOC, CDOM and Cu complexation capacities were reflected in Cu toxicity. DOM enriched samples presented a Cu EC(50) of 0.64 microM, significantly higher than the Cu EC(50) of natural and artificial seawater, which was 0.38 microM. The protecting effect of DOM on Cu toxicity greatly disappeared when the samples were irradiated with high intensity UV-light. Cu toxicity could be successfully predicted considering ASV-labile Cu concentrations in the samples. Pb complexation by DOM was only detected in the DOM-enriched samples and caused little effect on Pb EC(50). This effect was contrary for both elutriates: one elutriate reduced Pb toxicity in comparison with the control artificial seawater, while the other increased it. UV irradiation of the samples caused a marked increase in Pb toxicity, which correlated with the remaining DOC concentration. DOM parameters were related to Cu speciation and toxicity: good correlations were found between DOC and Cu EC(50), while L(Cu) correlated better with the fluorescence of marine humic substances. The present results stress the importance of characterizing not only the amount but also the quality of seawater DOM to better predict ecological effects from total metal concentration data.
采集了具有不同来源的水样，包括天然海水、两种沉积物洗脱液和受污水影响的海水，以研究存在的溶解有机物 (DOM) 对金属生物利用度的影响。测定了这些材料的有色 DOM 部分 (CDOM) 的碳含量 (DOC) 和光学性质（吸光度和荧光）。通过阳极溶出伏安法 (ASV) 测量 Cu 和 Pb 的络合特性，并通过 Paracentrotus lividus 胚胎 - 幼虫生物测定研究 DOM 对 Cu 和 Pb 生物利用度的影响。沉积物洗脱液和受污水（1）的 DOC 富集了 1.4-1.7 倍；（2）吸收和再发射更多的光；（3）与用于制备它们的天然海水相比，具有更高的 Cu 络合能力（L(Cu)）。L(Cu) 从天然海水中的 0.08 μM 变化到沉积物洗脱液和受污水中的 0.3 和 0.5 μM。DOC、CDOM 和 Cu 络合能力的差异反映在 Cu 毒性中。DOM 富集样品的 Cu EC(50) 为 0.64 μM，明显高于天然和人工海水的 Cu EC(50)，即 0.38 μM。当用高强度紫外线照射样品时，DOM 对 Cu 毒性的保护作用大大消失。可以成功地根据样品中的 ASV-不稳定 Cu 浓度预测 Cu 毒性。仅在 DOM 富集的样品中检测到 DOM 对 Pb 的络合作用，并且对 Pb EC(50) 的影响很小。这两种洗脱液的效果相反：一种洗脱液与对照人工海水相比降低了 Pb 毒性，而另一种则增加了毒性。样品的紫外线照射导致 Pb 毒性显著增加，这与剩余的 DOC 浓度相关。DOM 参数与 Cu 形态和毒性相关：DOC 与 Cu EC(50) 之间存在良好的相关性，而 L(Cu) 与海洋腐殖质的荧光相关性更好。目前的结果强调了不仅要表征海水 DOM 的数量，还要表征其质量的重要性，以便更好地根据总金属浓度数据预测生态效应。
