Electron microscopy and sediment geochemical data from a river basin (the upper Chicamocha river basin, UCRB, Boyacá province, Colombia) affected by anthropogenic activities (wastewater discharges, smelting and agricultural activities) showed the existence of heterogeneously distributed Zn particles in the sediments and sediments with Zn contents above the regional background (42 mg/kg). The objective of this study was to evidence the ZnS sedimentary neoformation in organic matter rich sediments deposited in anthropogenic reservoirs to reveal the processes involved in the sedimentary uptake of Zn from potential pollution sources. The highest Zn concentrations are found in clay minerals and organic matter-rich sediments (up to 427 mg/kg) deposited in slow-flowing reaches of the river associated to La Playa dam. Quartz-rich sediments poor in organic matter deposited in fast flowing segments of the river show very low Zn contents (1–12 mg/kg). Electron microscopy images showed ZnS nanoparticles forming cell-shaped aggregates suggesting that sulfate-reducing microorganisms acted as templates for the partial binding of Zn and for the nucleation and growth of zinc sulfide minerals. A good correlation of Zn with total organic carbon (r = 0.936) and the low potential redox of these sediments (−233 mV) suggest that organic matter was able to maintain oxygen depleted conditions appropriate to the Zn accumulation in the sediments. Our results demonstrate that potentially toxic Zn, originating from anthropic activities, was partially immobilized in organic matter-rich sediments through the precipitation of sulfides.

中文翻译：

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Chicamocha河（Boyacá-Colombia）受污染的有机质富集沉积物中锌生物自生硫化物形成的电子显微镜证据。

来自人类活动（废水排放，冶炼和农业活动）影响的流域（哥伦比亚博卡亚省的UCcam，上游奇卡莫查河流域）的电子显微镜和沉积物地球化学数据表明，沉积物和沉积物中存在分布不均的锌颗粒锌含量高于区域背景（42 mg / kg）。这项研究的目的是证明人为水库中富含有机物的沉积物中ZnS的沉积新形成，以揭示潜在污染源对Zn沉积物吸收的过程。在与La Playa大坝有关的河流慢流河段沉积的粘土矿物和富含有机物质的沉积物中发现最高的Zn浓度（最高427 mg / kg）。在快速流动的河段中沉积的富含有机物质的富含石英的沉积物显示出非常低的锌含量（1-12 mg / kg）。电子显微镜图像显示ZnS纳米颗粒形成细胞状聚集体，表明硫酸盐还原微生物充当模板，用于锌的部分结合以及硫化锌矿物的成核和生长。锌与总有机碳（r = 0.936）和这些沉积物的低电势氧化还原（-233 mV）表明有机物能够维持适合沉积物中Zn积累的贫氧条件。我们的结果表明，源自人类活动的潜在毒性锌通过硫化物的沉淀被部分固定在富含有机物的沉积物中。