Department of Chemistry, University of Lagos, Akoka, Lagos, Nigeria.
Department of Chemical Sciences, Tai Solarin University of Education, Ijagun, Ogun State, Nigeria.
Environ Monit Assess. 2021 Jun 12;193(7):416. doi: 10.1007/s10661-021-09165-0.
Spatial variations and mobility of mercury (Hg) and Hg associations with other potentially toxic elements (PTEs) were studied in soil samples from Alaba, the largest e-waste recycling site in Nigeria and West Africa. Total Hg concentration was determined in surface soil samples from various locations using cold vapour atomic absorption spectrometry (CVAAS) following microwave-assisted acid extraction, while sequential extraction was used to determine operationally defined mobility. The concentrations of the PTEs arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn) metals were determined using inductively coupled plasma mass spectrometry (ICP-MS) following microwave-assisted digestion with aqua regia. Total Hg concentration ranged from < 0.07 to 624 mg/kg and was largely dependent on the nature and intensity of e-waste recycling activities carried out. Mobile forms of Hg, which may be HgO (a known component of some forms of e-waste), accounted for between 3.2 and 23% of the total Hg concentration, and were observed to decrease with increasing organic matter (OM). Non-mobile forms accounted for >74% of the total Hg content. In the main recycling area, soil concentrations of Cd, Cd, Cu, Hg, Mn, Ni, Pb and Zn were above soil guideline values (Environment Agency in Science Report, 2009; Kamunda et al., 2016). Strong associations were observed between Hg and other PTEs (except for Fe and Zn) with the correlational coefficient ranging from 0.731 with Cr to 0.990 with As in April, but these correlations decreased in June except for Fe. Hazard quotient values > 1 at two locations suggest that Hg may pose health threats to people working at the e-waste recycling site. It is therefore recommended that workers should be investigated for symptoms of Hg exposure.
在尼日利亚和西非最大的电子废物回收地阿拉巴，研究了土壤样品中汞（Hg）及其与其他潜在有毒元素（PTE）的空间变化和迁移。使用冷蒸气原子吸收光谱法（CVAAS）在微波辅助酸提取后测定了来自不同地点的表层土壤样品中的总 Hg 浓度，而连续提取则用于确定操作定义的迁移率。使用电感耦合等离子体质谱法（ICP-MS）在微波辅助王水消解后测定了砷（As）、镉（Cd）、铬（Cr）、铜（Cu）、锰（Mn）、汞（Hg）、镍（Ni）、铅（Pb）和锌（Zn）金属的浓度。总 Hg 浓度范围为<0.07-624 mg/kg，主要取决于进行的电子废物回收活动的性质和强度。可能是某些形式的电子废物的一部分的 HgO（一种已知的 Hg 形式）的可迁移形式占总 Hg 浓度的 3.2-23%，并且随着有机质（OM）的增加而减少。不可移动的形式占总 Hg 含量的>74%。在主要的回收区，土壤中 Cd、Cd、Cu、Hg、Mn、Ni、Pb 和 Zn 的浓度高于土壤指导值（环境署科学报告，2009 年；Kamunda 等人，2016 年）。在 4 月，Hg 与其他 PTE（除 Fe 和 Zn 外）之间观察到强烈的相关性，相关系数从与 Cr 的 0.731 到与 As 的 0.990，而在 6 月，除了 Fe 之外，这些相关性下降。在两个地点，危害商值>1 表明 Hg 可能对在电子废物回收场工作的人构成健康威胁。因此，建议对工人进行 Hg 暴露症状调查。
