Department of Geology, University of Ibadan, Ibadan, Nigeria.
Department of Geology, Afe Babalola University, Ado-Ekiti, Ekiti State, Nigeria.
Environ Geochem Health. 2020 Apr;42(4):1095-1107. doi: 10.1007/s10653-019-00330-6. Epub 2019 May 31.
Lead (Pb) is of considerable concern among other heavy metals because of its toxic impact on the environment and human health. The geochemical nature and source-transport-fate of Pb in Nigeria's environmental media are relatively unknown. This study was undertaken to quantify and characterize Pb in soils, sediments and road dusts from Lagos, Nigeria. A total of forty-eight soil samples, seventeen sediment samples and thirteen roadside soils were collected from within Lagos metropolis. The samples were air-dried, screened, pulverized and sieved through 63-µm nylon mesh. Mineralogical constituent of samples were determined using X-ray diffraction. The sieved fractions and pulverized rock samples were digested and analyzed for elemental Pb components using inductively coupled plasma mass spectrometry (ICP-MS). The chemical fractionations of Pb in the samples were determined by sequential analysis. Lead isotope compositions of the samples were determined using quadrupole-based ICP-MS. Lead isotopic ratios and geo-accumulation indexes were used for discriminating and evaluating Pb sources. Quartz, microcline, K-feldspar, plagioclase and kaolinite were the preponderant minerals in powdered rocks, soils and sediments. The concentration (mg/kg) of elemental Pb in sediments and dusts for Lagos was 21-1963; 23-830 and 22-830, respectively. The plots (Pb/Pb)/(Pb/Pb) revealed that the Pb in the environmental media was derived from anthropogenic sources. The Pb isotopic ratios for soils, sediments and dusts were characterized by lower Pb/Pb ratios, compared to bedrock. The Pb contents are held principally in the organic sulfide and reducible and carbonate phases. The Pb is held in very reactive geochemical phases, and these portend great risk to the environment and public health.
铅（Pb）是其他重金属中备受关注的一种，因为它对环境和人类健康具有毒性影响。尼日利亚环境介质中 Pb 的地球化学性质和来源-输运-命运相对未知。本研究旨在定量和表征尼日利亚拉各斯的土壤、沉积物和道路灰尘中的 Pb。总共从拉各斯大都市内采集了四十八个土壤样本、十七个沉积物样本和十三个路边土壤样本。这些样本在空气中干燥、筛选、粉碎并通过 63-µm 尼龙网进行筛分。使用 X 射线衍射法确定样品的矿物成分。对筛选的部分和粉碎的岩石样品进行消解，并使用电感耦合等离子体质谱法（ICP-MS）分析元素 Pb 成分。通过顺序分析确定样品中 Pb 的化学分级。使用基于四极的 ICP-MS 确定样品的 Pb 同位素组成。Pb 同位素比值和地质累积指数用于区分和评估 Pb 来源。在粉末状岩石、土壤和沉积物中，优势矿物为石英、微斜长石、钾长石、斜长石和高岭石。拉各斯沉积物和灰尘中元素 Pb 的浓度（mg/kg）分别为 21-1963；23-830 和 22-830。Pb/Pb 和 Pb/Pb 的图表明，环境介质中的 Pb 源自人为来源。与基岩相比，土壤、沉积物和灰尘的 Pb 同位素比值具有较低的 Pb/Pb 比值。Pb 主要存在于有机硫化物、可还原和碳酸盐相中。Pb 存在于非常活跃的地球化学相中，这对环境和公共健康构成了巨大风险。
