Mineralogical characteristics of sediments and heavy metal mobilization along a river watershed affected by acid mine drainage

Abstract

Trace-element concentrations in acid mine drainage (AMD) are primarily controlled by the mineralogy at the sediment-water interface. Results are presented for a combined geochemical and mineralogical survey of Dabaoshan Mine, South China. Developed sequential extraction experiments with the analysis of the main mineralogical phases by semi-quantitative XRD, differential X-ray diffraction (DXRD) and scanning electron microscopy (SEM) were conducted to identify the quantitative relationship between iron minerals and heavy metals. Results showed that schwertmannite, jarosite, goethite and ferrihydrite were the dominant Fe-oxyhydroxide minerals which were detected alternately in the surface sediment with the increasing pH from 2.50 to 6.93 along the Hengshi River. Decreasing contents of schwertmannite ranging from 35 wt % to 6.5 wt % were detected along the Hengshi River, which was corresponding to the decreasing metal contents. The easily reducible fractions exert higher affinity of metals while compared with reducible and relatively stable minerals. A qualitative analysis of heavy metals extracted from the sediments indicated that the retention ability varied: Pb > Mn > Zn > As ≈ Cu > Cr > Cd ≈ Ni. Results in this study are avail for understanding the fate and transport of heavy metals associated with iron minerals and establishing the remediation strategies of AMD systems.

The use of operationally-defined sequential Fe extraction methods for mineralogical applications: A cautionary tale from Mössbauer spectroscopy

“…Examples of secondary analyses used to verify the Fe minerals or mineral groups present in the extracted leachate or the residual material, include MBS (Jilbert et al, 2018;Sun et al, 2018;Schröder et al, 2016), LA-ICP-MS (Oonk et al, 2018), SEM or TEM (Xie et al, 2018;Zhuang et al, 2012), XAS (Sun et al, 2018;Barber et al, 2017), tests with 58 Fe isotope spiking (Henkel et al 2016), or a percentage yield comparison from a single mineral control or internal laboratory standard (Jin et al, 2018;Liu et al, 2018;Lynch et al, 2018;Qi et al, 2018;Lei et al, 2017;Oonk et al, 2017;Xie et al, 2017;Raiswell et al, 2010). The advantage of MBS is the ability to analyse a sample non-destructively and in a single, short step without additional preparation.…”

Fractionation distribution and ecological risk assessment of some trace metals in artificial estuary: Vridi channel (Côte d'Ivoire)

“…As shown table 1 and fig.3, Cd, Ni and Pb present very high accuracy Values. These high recovery values can be explained by lower efficiency of digestion of the HF acid mixture with high Ca content, which trapped calcium fluoroaluminate or calcium precipitates and was affected by interferences [36][37][38]. Also, it is hypothesized that Ni and Pb in these samples are partly associated with HF-refractory minerals such as Fe-Mn oxihydroxides, which act as a trap for these trace metals.…”

A Review: Assessment of Trace Metals in Municipal Sewage and Sludge: A Case Study of Limpopo Province, South Africa

“…The sewage effluent rich in metals is discharged into rivers and streams, and the metals either stay in solution or are trapped in complex sediments and pollution sinks [53]. The metals in the sediments can be released back into the water column should the environmental conditions change, such as pH becoming acidic, with devastating consequences on aquatic life and human health [15,54] or during flood conditions [55].…”