这项研究调查了受多种城市和工业铜源影响的巴西红树林中铜(Cu)污染及其稳定同位素的年代学,森林砍伐,和富营养化。特别是,它测试了Cu同位素作为人为输入到受多种来源影响的人为流域的示踪剂。要做到这一点,我们使用了多同位素方法(δ65Cu,δ13C,和δ15N),元素分析(Al,Ca,Fe,P,Cu,C,andN),以及在210Pb年代沉积岩心中的选择性和顺序提取。这个地球化学“工具箱”允许确定沉积物核心中Cu演化的两个主要阶段。在第一阶段,在1965年之前,铜同位素指纹对景观变化做出了反应,表明由于陆地材料的重新动员和侵蚀,从海洋到地质优势的转变。在第二阶段,1965年以后,沉积物地球化学剖面显示铜总浓度增加,生物有效性较高(如顺序提取数据所反映的),伴随着铜同位素特征向人为值的变化。调查结果证明,当地的工业来源,可能与分散的城市来源相结合,将Cu输出到下游红树林中,与自然值相比具有可区分的同位素特征。这项研究证明了铜同位素作为新的环境法医工具在红树林沉积物中追踪人为来源的适用性。纳入一个强大的地球化学工具箱,结合了无机和有机沉积材料的代理,这个新工具提供了对红树林生态系统中Cu动态的全面了解,揭示铜的历史和当前来源。
This study investigates the chronology of copper (Cu) contamination and its stable isotopes within an emblematic Brazilian mangrove impacted by multiple urban and industrial Cu sources, deforestation, and eutrophication. In particular, it tests Cu isotopes as tracers of anthropogenic inputs into an anthropized watershed impacted by multiple sources. To do so, we used multi-isotopic approaches (δ65Cu, δ13C, and δ15N), elemental analyses (Al, Ca, Fe, P, Cu, C, and N), and selective and sequential extractions in a210Pb-dated sediment core. This geochemical \"toolbox\" allowed identifying two main stages of Cu evolution in the sediment core. In the first stage, before 1965, Cu isotope fingerprints responded to landscape changes, indicating a shift from marine to geogenic dominance due to the remobilization and erosion of terrestrial materials. In the second stage, after 1965, the sediment geochemical profile showed increased Cu total concentrations with a higher bioavailability (as reflected by sequential extraction data) accompanying changes in Cu isotope signatures towards anthropogenic values. The findings evidence that local industrial sources, possibly combined with diffuse urban sources, export Cu into downstream mangroves with a distinguishable isotope signature compared to natural values. This study demonstrates the applicability of Cu isotopes as new environmental forensic tools to trace anthropogenic sources in mangrove sediments. Incorporated into a robust geochemical toolbox that combines inorganic and organic proxies for sedimentary materials, this new tool provides a comprehensive understanding of Cu dynamics in mangrove ecosystems, shedding light on the historical and current sources of Cu.