ABSTRACT

The objective of this study was to determine the occurrence, origin, and risk of Cadmium (Cd), lead (Pb), chromium (Cr), nickel (Ni), copper (Cu), manganese (Mn), zinc (Zn), and iron (Fe) in soil profiles from petroleum tank-farms in Western Delta, Nigeria. The soil samples were digested with aqua-regia, and the concentrations of the metals were determined using an atomic absorption spectrophotometry. The mean concentrations of metals varied for all sites and depths and ranged from 1.86 ± 1.73 mg kg⁻¹ (Cd) to 3535 ± 1802 mg kg⁻¹ (Fe). The mean concentrations of Cd, Pb, and Cu exceeded the Dutch and DPR-EGASPIN target limits in 80%, 5%, and 45% of the samples, respectively. Concerning soil depths, the metals showed irregular occurrence and exhibited concentration load in the order of subsoil > bottom soil > topsoil. The results also showed that the metals had the highest concentrations at site SS1, SS2, SS4, SS6, SS8, SS9, SS10, and SS11. The linear regression between TOC and metals indicates a weak correlation. The ANOVA shows that there is a significant variation for the total concentrations of the metals concerning soil depths. The PCA, enrichment factors and the geo-accumulation index suggest that the trace metals originated from the anthropogenic and geologic means. The average contamination factor and the ecological risk factor followed the order: Cd > Pb > Cu > Zn > Mn > Cr > Ni, and Cd > Pb > Cu > Ni > Zn > Cr > Mn, respectively. The non-carcinogenic risk shows no adverse non-carcinogenic health effects for human exposure to metals. The total cancer risk values are within acceptable safety limits. The results of the heavy metals from this study suggest that soils from the petroleum tank farms require sustainable remediation measures.

摘要

这项研究的目的是确定镉（Cd），铅（Pb），铬（Cr），镍（Ni），铜（Cu），锰（Mn），锌（Zn）的发生，来源和风险和尼日利亚西部三角洲石油储罐农场土壤剖面中的铁（Fe）。用王水消化土壤样品，并使用原子吸收分光光度法测定金属的浓度。金属的平均浓度因位置和深度而异，范围为1.86±1.73 mg kg ^-1（Cd）至3535±1802 mg kg ^-1（铁）Cd，Pb和Cu的平均浓度分别超过80％，5％和45％的样品的Dutch和DPR-EGASPIN目标限值。在土壤深度方面，金属表现出不规则的存在，并表现出按底土>底部土壤>表层土的浓度负荷。结果还表明，金属在SS1，SS2，SS4，SS6，SS8，SS9，SS10和SS11处的浓度最高。TOC和金属之间的线性回归表明相关性较弱。方差分析表明，涉及土壤深度的金属总浓度存在显着差异。PCA，富集因子和地质积累指数表明，痕量金属起源于人为和地质手段。平均污染因子和生态风险因子的顺序为：Cd> 铅>铜>锌>锰>铬>镍，镉>铅>铜>镍>锌>铬>锰。非致癌风险表明，人类接触金属不会对健康造成不利影响。总癌症风险值在可接受的安全范围内。这项研究的重金属结果表明，石油储罐场的土壤需要采取可持续的补救措施。