Uptake and speciation of trace metal inputs to Wetland Soils from Illinois and South Carolina and Stream Sediments from Tennessee

Metals occur in all ecosystems, although their concentrations vary depending on their natural geologic conditions and surrounding human activities. In addition to metals intrinsically present from the geology of a particular system, metals can enter environmental systems from a wide variety of natural and anthropogenic sources, such as sediment re-suspension, mining operations, industrial processes, agricultural activities, and atmospheric deposition. While metals can be toxic at high concentrations, some metals serve as essential micronutrients for biogeochemical processes. Metal transport and availability in engineered and natural water systems depend on processes of adsorption/desorption, oxidation/reduction, dissolution/precipitation, and ligand complexation. Insights into the speciation of metals and their bioavailability will also help advance understanding of the roles of metals in the biogeochemical cycling of nutrients. We conducted batch experiments under anoxic conditions on soils and sediments collected from three different natural aquatic systems to understand their response to influxes of dissolved Cu, Ni and Zn. While soils and sediments from all sites could strongly bind added trace metals, there were substantial differences in trace metal uptake trends between different sites, especially for Cu. There was no distinct correlation between trace metal uptake and the total organic matter, iron, and sulfur content present in the samples. X-ray absorption spectroscopy indicated that the speciation of the freshly added metals taken up by the solids differs substantially from the speciation of the metals originally present in unamended samples. Cu sulfides dominated speciation at low loadings (1 µmol/g), whereas complexation to thiol groups and formation of metallic Cu governed speciation at high loadings (10 µmol/g). For Ni and Zn, adsorption to mineral surfaces and organic matter governed their speciation in materials from most sites. This study suggests that the background speciation of metals in natural aquatic systems is a poor predictor of the speciation and lability of metals introduced to terrestrial aquatic systems from anthropogenic or natural processes. Our findings imply that geochemical processes controlling trace metal speciation may vary considerably with metal loading in different natural systems. Data are provided for marsh wetland soils at Argonne National Laboratory (Marsh 1 and Marsh 2), riparian wetland soils (Riparian 1 and Riparian 2) in the Tims Branch watershed at Savannah River National Laboratory, and stream bed sediments (Stream 1 and Stream 2) from East Fork Poplar Creek near Oak Ridge National Laboratory. Data package includes the results of trace metal uptake experiments conducted on the selected sites for determining their capacity to immobilize metals under different loadings. XANES spectra for Cu, Ni, ad Zn at different loadings are included in the package. The abundance of different trace metal species obtained using linear combination fitting in ATHENA are also included in the data.金属广泛分布于各类生态系统中，其浓度因自然地质条件及周边人类活动的差异而有所波动。除特定系统地质本底天然赋存的金属外，环境系统中的金属还可通过多种自然及人为（anthropogenic）来源进入环境，例如沉积物再悬浮、采矿作业、工业生产流程、农业活动以及大气沉降。尽管高浓度金属具有毒性，但部分金属是生物地球化学（biogeochemical）过程必需的微量营养素。工程化与天然水系统中，金属的迁移行为与生物有效性取决于吸附/解吸（adsorption/desorption）、氧化还原（oxidation/reduction）、溶解/沉淀（dissolution/precipitation）以及配位络合（ligand complexation）等过程。深入解析金属的形态特征及其生物有效性，有助于进一步理解金属在营养物质生物地球化学循环中的作用机制。我们针对从三个不同天然水生系统采集的土壤与沉积物，在厌氧（anoxic）条件下开展批次实验，以探究其对溶解态铜（Cu）、镍（Ni）与锌（Zn）输入的响应特征。尽管所有采样点的土壤与沉积物均能强力结合添加的痕量金属，但不同采样点间的痕量金属吸附趋势存在显著差异，尤以铜最为突出。痕量金属吸附量与样品中总有机质、铁及硫含量之间未呈现显著相关性。X射线吸收光谱（X-ray absorption spectroscopy）分析表明，固体所吸附的新增金属的形态，与未添加金属的原始样品中固有金属的形态存在显著差异。低负载量（1 µmol/g）下，硫化铜主导金属形态分布；而高负载量（10 µmol/g）下，巯基（thiol groups）络合作用与金属铜的生成共同主导形态转化。对于镍与锌，多数采样点样品中其形态主要受矿物表面与有机质吸附作用控制。本研究表明，天然水生系统中金属的本底形态，无法有效预测人为或自然过程引入至陆地水生系统的金属的形态与反应活性。我们的研究结果暗示，控制痕量金属形态的地球化学过程，在不同自然系统中可能随金属负载量发生显著变化。本数据集包含以下三类样品的相关数据：阿贡国家实验室（Argonne National Laboratory）的沼泽湿地土壤（沼泽1号与沼泽2号）、萨凡纳河国家实验室（Savannah River National Laboratory）廷斯分支流域的河岸湿地土壤（河岸1号与河岸2号），以及橡树岭国家实验室（Oak Ridge National Laboratory）附近的波普勒溪东支流的河床沉积物（溪流1号与溪流2号）。数据包涵盖了针对所选采样点开展的痕量金属吸附实验结果，用于测定其在不同负载量下固定金属的能力；同时包含了不同负载量下铜、镍及锌的X射线吸收近边结构光谱（XANES）数据；此外还收录了通过ATHENA软件进行线性组合拟合得到的不同痕量金属物种的占比数据。