| Arsenic pollution is a global environmental problem,and mining activities are one of the sources of arsenic pollution.Monitoring,evaluating,and controlling pollution is key to solving environmental problems,while the former two are prerequisites for the latter.Portable X-Ray fluorescence(PXRF)is a portable device capable of rapid,nondestructive,economical,and multi-elemental analysis.In this research,PXRF was used to assess the arsenic pollution in Bailing Cu-Pb polymetallic deposit area,containing dust pollution,soil pollution,and arsenic enrichment in plants.Some related issues such as sample preparation,PXRF data quality,and calibration models were studied.PXRF data were used to comprehensively evaluated the arsenic pollution level in Bailing Cu-Pb polymetallic deposit areas.Forest coverage area in Bailing Cu-Pb polymetallic deposit area suffered from road dust pollution in the mining area.PXRF was used to determine the elemental concentrations in cross-sectional area of tree stems and soils in corresponding location.Concentrations of As,Zn,and Fe displayed obvious zonation along the direction perpendicular to the road in the mining area.Arsenic,Zn,and Fe concentrations are highest in the area nearest to the road.Arsenic and Zn concentrations generally decreased with increasing distance to the road,conforming to the power law distribution.The micro-X-Ray fluorescence(micro-XRF)scanning images suggest that elements such as As,Zn,and Fe mainly concentrated on crosssectional area and vertical fractures of tree stems,indicating that the pollution was caused by the re-deposition of road dust.Dust blown from roads is a major pathway of arsenic exposure.PXRF was used to evaluate the arsenic pollution of farmland soil in the mining area.PXRF analyses in a laboratory setting can quantitatively determine As,Mn,Fe,and Zn concentrations.The correlation between As and other elements(Ca,Mn,Fe,Zn,Pb,V,Ti,Rb,and K)was concluded by Pearson correlation analysis of elemental concentrations in farmland soils.A significant As-anomaly was found near the river in the west of the farmland,and the As concentrations decrease from surface to underground in a vertical direction.The sequential extraction procedure(SEP)results of the core soil samples suggest that the percentage of As in mild acido-soluble fraction and reducible fraction in top soils are much higher than those in underground soils.The elemental distribution in the farmland and the SEP results of the farmland soils indicate the source of As pollution.The river overflows the farmland after heavy rainfall and As in the river system may enter into the soil system through co-precipitation and/or adsorption by Fe/Mn oxides.The effects of sample moisture content,sample density,and sample thickness on PXRF readings were experimentally determined by analyzing organic samples via PXRF.A sample preparation method for organic samples was provided and a linear regression calibration model was established for correcting matrix effect on PXRF readings.The validation results suggest that the linear regression calibration model can substantially improve the predictive accuracy of PXRF readings for organic samples.PXRF is generally capable of quantative elemental analysis of organic samples.The vegetation in the mining area was subjected to PXRF analysis following the established sample preparation method,and original PXRF data were calibrated using the linear regression calibration model.PXRF results suggest that ingestion of wild edible mushrooms(e.g.Cortinarius collinitus Fr.)is one of the pathways of arsenic exposure.PXRF demonstrated a strong capability for screening hyperaccumulator plants. |
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