Abstract
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.
Highlights
Pollution by heavy metals is of particular concern for humans because of their detrimental health effects on people in excessive quantities
X-ray diffraction (XRD) diffraction patterns reveal that the mineral assemblage of the alluvial sediments from the Chicamocha River is dominated by the presence of quartz and kaolinite
Mineral assemblage is contrastingly different in sediments from La Playa reservoir at the central part of the Upper Chicamocha River Basin (UCRB), where oriented aggregates of the
Summary
Pollution by heavy metals is of particular concern for humans because of their detrimental health effects on people in excessive quantities. Contaminated geomaterials in areas heavily utilized by people, including extensively used recreational zones in towns [1] or agricultural fields [2,3], can create potential risk of metal exposure to humans. Alluvial sediments in river basins can accumulate or release heavy metals depending on flow regime and flooding [4]. The presence of dams regulate the surface water outflow in river basins and causes slow-flowing sites and flooding. The area of the UCRB is around 214,000 ha, with a length of 62.46 km and an average slope of 0.12% [24]. March and November are the warmest months.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
