Department of Environmental Science, Institute of Biomedical Studies, Center for Reservoir and Aquatic Systems Research (CRASR), Baylor University , Waco, Texas 76798, United States.
U.S. Geological Survey, Boulder, Colorado 80303, United States.
Environ Sci Technol. 2017 Feb 7;51(3):1395-1404. doi: 10.1021/acs.est.6b04672. Epub 2017 Jan 27.
The toxicity of soluble metal-based nanomaterials may be due to the uptake of metals in both dissolved and nanoparticulate forms, but the relative contributions of these different forms to overall metal uptake rates under environmental conditions are not quantitatively defined. Here, we investigated the linkage between the dissolution rates of copper(II) oxide (CuO) nanoparticles (NPs) and their bioavailability to Gulf killifish (Fundulus grandis) embryos, with the aim of quantitatively delineating the relative contributions of nanoparticulate and dissolved species for Cu uptake. Gulf killifish embryos were exposed to dissolved Cu and CuO NP mixtures comprising a range of pH values (6.3-7.5) and three types of natural organic matter (NOM) isolates at various concentrations (0.1-10 mg-C L), resulting in a wide range of CuO NP dissolution rates that subsequently influenced Cu uptake. First-order dissolution rate constants of CuO NPs increased with increasing NOM concentration and for NOM isolates with higher aromaticity, as indicated by specific ultraviolet absorbance (SUVA), while Cu uptake rate constants of both dissolved Cu and CuO NP decreased with NOM concentration and aromaticity. As a result, the relative contribution of dissolved Cu and nanoparticulate CuO species for the overall Cu uptake rate was insensitive to NOM type or concentration but largely determined by the percentage of CuO that dissolved. These findings highlight SUVA and aromaticity as key NOM properties affecting the dissolution kinetics and bioavailability of soluble metal-based nanomaterials in organic-rich waters. These properties could be used in the incorporation of dissolution kinetics into predictive models for environmental risks of nanomaterials.
可溶性金属基纳米材料的毒性可能是由于金属以溶解态和纳米颗粒态两种形式被吸收所致，但在环境条件下，这些不同形态对总金属吸收速率的相对贡献尚未定量确定。在这里，我们研究了氧化铜 (CuO) 纳米颗粒 (NPs) 的溶解速率与海湾食蚊鱼 (Fundulus grandis) 胚胎生物可利用性之间的联系，目的是定量描述纳米颗粒和溶解态物质对 Cu 吸收的相对贡献。将海湾食蚊鱼胚胎暴露于溶解态 Cu 和包含一系列 pH 值 (6.3-7.5) 和三种类型天然有机物 (NOM) 分离物的 CuO NP 混合物中，在不同浓度 (0.1-10 mg-C L) 下，导致 CuO NP 溶解速率的广泛变化，从而影响 Cu 吸收。CuO NPs 的一级溶解速率常数随着 NOM 浓度的增加而增加，对于芳香度较高的 NOM 分离物也是如此，这可以通过特定紫外吸光度 (SUVA) 来指示，而溶解态 Cu 和 CuO NP 的 Cu 吸收速率常数则随着 NOM 浓度和芳香度的增加而降低。因此，溶解态 Cu 和纳米颗粒态 CuO 物种对总 Cu 吸收速率的相对贡献不受 NOM 类型或浓度的影响，但主要取决于溶解的 CuO 百分比。这些发现强调了 SUVA 和芳香度作为影响富含有机物水中可溶性金属基纳米材料溶解动力学和生物可利用性的关键 NOM 特性。这些特性可用于将溶解动力学纳入纳米材料环境风险的预测模型中。
