Arhin Emmanuel, Boansi Apea Ohene, Zango M S
Department of Earth and Environmental Sciences, Faculty of Applied Sciences, University for Development Studies, P. O. Box 24, Navrongo, Ghana.
Environ Geochem Health. 2016 Feb;38(1):203-18. doi: 10.1007/s10653-015-9705-0. Epub 2015 Apr 24.
Environmental geochemistry classifies elements into essential, non-essential and toxic elements in relationship to human health. To assess the environmental impact of mining at Datoko-Shega area, the distributions and concentrations of trace elements in stream sediments and soil samples were carried out. X-ray fluorescence analytical technique was used to measure the major and trace element concentrations in sediments and modified fire assay absorption spectrometry in soils. The results showed general depletion of major elements except titanium oxide (TiO2) compared to the average crustal concentrations. The retention of TiO2 at the near surface environment probably was due to the intense tropical weathering accompanied by the removal of fine sediments and soil fractions during the harmattan season by the dry north-east trade winds and sheet wash deposits formed after flash floods. The results also showed extreme contamination of selenium (Se), cadmium (Cd) and mercury (Hg), plus strong contaminations of arsenic (As) and chromium (Cr) in addition to moderate contamination of lead (Pb) in the trace element samples relative to crustal averages in the upper continental crust. However Hg, Pb and Cd concentrations tend to be high around the artisanal workings. It was recognised from the analysis of the results that the artisanal mining activity harnessed and introduces some potentially toxic elements such as Hg, Cd and Pb mostly in the artisan mine sites. But the interpretation of the trace element data thus invalidates the elevation of As concentrations to be from the mine operations. It consequently noticed As values in the mine-impacted areas to be similar or sometimes lower than As values in areas outside the mine sites from the stream sediment results.
环境地球化学根据元素与人类健康的关系将其分为必需元素、非必需元素和有毒元素。为了评估达托科-谢加地区采矿对环境的影响，对河流沉积物和土壤样本中的微量元素分布及浓度进行了研究。采用X射线荧光分析技术测定沉积物中的主要元素和微量元素浓度，土壤中则采用改进的火试金吸收光谱法。结果表明，与地壳平均浓度相比，除二氧化钛（TiO₂）外，主要元素普遍贫化。TiO₂在近地表环境中的留存可能是由于强烈的热带风化作用，同时在旱季东北信风期间细粒沉积物和土壤组分被带走，以及暴雨后形成的片流沉积物所致。结果还显示，相对于上地壳的地壳平均值，微量元素样本中硒（Se）、镉（Cd）和汞（Hg）受到极度污染，砷（As）和铬（Cr）受到强烈污染，铅（Pb）受到中度污染。然而，Hg、Pb和Cd的浓度在个体采矿作业区周围往往较高。从结果分析中认识到，个体采矿活动在很大程度上利用并引入了一些潜在有毒元素，如Hg-Cd和Pb，主要存在于个体矿场。但对微量元素数据的解读使将As浓度升高归因于采矿作业的说法无效。因此，根据河流沉积物结果，注意到受采矿影响地区的As值与矿场以外地区的As值相似，有时甚至更低。
