Instituto Geológico y Minero de España (IGME-CSIC), C/Rios Rosas 23, 28003 Madrid, Spain; Universidad Autonoma de Madrid-Campus de Cantoblanco, C/Francisco Tomás y Valiente, 7, 28049 Madrid, Spain.
Instituto Geológico y Minero de España (IGME-CSIC), Plaza de España, Torre Norte, 41013 Sevilla, Spain.
Sci Total Environ. 2023 Jan 20;857(Pt 3):159409. doi: 10.1016/j.scitotenv.2022.159409. Epub 2022 Oct 13.
Trace elements are serious pollutants in the natural environment and are of increasing concern due to the adverse effects at global scale. To refine the current understanding of trace metal distribution and variability in natural environments, concentrations of dissolved trace metals (Ag, Al, As, B, Ba, Be, Co, Cr, Cd, Cu, Fe, Hg, Mo, Ni, Pb, Sb, Se, Th,Tl, U, V, Mn, Zn), major ions, inorganic nutrients (NO, PO), TOC and stable isotopes of water were determined in water samples from rainwater, seven piezometers and a pond in the coastal Doñana wetland during four sampling campaigns between 2017 and 2019. Results show clear evaporation signatures of stable isotopes in the pond but not in the groundwater. Hydrochemical analyses yield significant, systematic changes in groundwater trace metal and nutrient composition along the flowpath from the dune belt to the pond, controlled by organic matter in the sediments. Whereas major ions reached maximum concentrations in the pond due to evapoconcentration, most trace metals showed highest concentrations at sites with lower redox levels, except for B, As and U, which showed very high concentrations in the pond. Cu, Zn, Ni, Sb and Tl yielded higher median concentrations in rainwater than in most of the groundwater points and in case of Cu and Zn higher even than in surface water which points to an atmospheric input source of these elements. Temporal variability of trace metals was related to lower hydraulic heads after an elongated dry period which led to lower redox levels and higher concentrations of most of the trace elements whereas major ions showed more constant concentration levels. This is of special concern regarding climate change and the predicted higher frequency of prolonged dry periods, which could modify the natural hydrochemical patterns in undisturbed wetlands systems.
微量元素是自然环境中的严重污染物，由于其在全球范围内的不利影响，越来越受到关注。为了更深入地了解自然环境中痕量金属的分布和变化，本研究测定了 2017 年至 2019 年期间四个采样季节中，雨水、七个测压计和多纳纳湿地沿海一个池塘中的溶解痕量金属（银、铝、砷、硼、钡、铍、钴、铬、镉、铜、铁、汞、钼、镍、铅、锑、硒、钍、铊、铀、钒、锰、锌）、主要离子、无机养分（硝酸盐、磷酸盐）、总有机碳和水样的稳定同位素。结果表明，池塘中的稳定同位素具有明显的蒸发特征，但地下水则没有。水化学分析表明，在从沙丘带流向池塘的过程中，痕量金属和养分组成发生了显著的、系统的变化，这是由沉积物中的有机物控制的。虽然主要离子在池塘中由于蒸发浓缩而达到最大浓度，但除硼、砷和铀外，大多数痕量金属在氧化还原水平较低的地点浓度最高，而硼、砷和铀在池塘中浓度非常高。铜、锌、镍、锑和铊在雨水中的中位数浓度高于大多数地下水点，而在铜和锌的情况下，甚至高于地表水，这表明这些元素的大气输入源。痕量金属的时间变化与延长干旱期后的较低水力水头有关，这导致大多数痕量元素的氧化还原水平降低和浓度升高，而主要离子的浓度水平则更为稳定。这特别令人关注，因为气候变化和预测的延长干旱期频率的增加可能会改变未受干扰的湿地系统中的自然水化学模式。
