Abstract

Owing to population growth and urbanization, there has been an increase in the number of auto mechanic workshops, vulcanizer’s shops and engine oil retail shops along the roads within Nsukka with a direct increase in heavy metal concentration in dust. Emissions from these activities pose serious environmental concern along the major roads. This study is centered on the assessment of heavy metal pollution in dust and top soil along major roads within Nsukka metropolis. Soil and dust samples were collected along major roads at maximum distance of five meters from the roads edge, with control samples collected 400 m away from the nearest road. Heavy metals (Cadmium, Zinc, Iron, Lead, Chromium, Arsenic, Copper, Nickel, and Manganese) concentrations in the dust and soil were analyzed using Atomic Absorption Spectrophotometry method. The result of the analyzed heavy metal concentration showed no significant variation from the background concentration. The concentrations of Pb and Cr showed little variation, whereas As showed the greatest variation from the background value. The results of heavy metals contamination factor in soil and dust ranged from low contamination to very high contamination (CF < 1; to CF ≥ 6). High and very high contamination values were obtained for As, Cr, and Mn in both dust and soil samples. The enrichment factor of heavy metals ranged from EF ≤ 1 (background rank) to EF> 40 (extremely high enrichment). Among the analyzed heavy metals, Zn, Pb, As, and Cr showed the highest enrichments in both soil and dust samples respectively. The result of Igeo ranged from Igeo ≤ 0 (uncontaminated) to 2 < Igeo < 3 (moderately to heavily contaminated). In the dust and soil samples, Igeo for Zn, Pb, Cd, Ni, and Cu show no contamination; Igeo for As and Cr showed moderate contaminations in some locations whereas that of Mn showed moderate to heavy contamination. Results of PLI ranged from PLI < 1 (no pollution) to 3 <PLI (extremely heavy pollution).

摘要

由于人口增长和城市化，恩苏卡内道路沿线的汽车修理厂、硫化机商店和机油零售店的数量增加，灰尘中的重金属浓度直接增加。这些活动产生的排放物对主要道路沿线的环境造成严重影响。本研究的重点是评估恩苏卡大都市主要道路沿线的灰尘和表层土壤中的重金属污染。沿主要道路收集土壤和灰尘样品，距离道路边缘最远 5 米，控制样品距离最近的道路 400 m 收集。使用原子吸收分光光度法分析灰尘和土壤中的重金属（镉、锌、铁、铅、铬、砷、铜、镍和锰）浓度。分析的重金属浓度结果与背景浓度没有显着差异。Pb 和 Cr 的浓度变化不大，而 As 与背景值的变化最大。土壤和灰尘中重金属污染因子的结果范围从低污染到非常高污染（CF < 1；到CF ≥ 6）。灰尘和土壤样品中的 As、Cr 和 Mn 的污染值都很高和非常高。重金属的富集因子范围从EF≤1（背景等级）到EF>40（极高富集度）。在分析的重金属中，Zn、Pb、As 和 Cr 分别在土壤和灰尘样品中的富集度最高。Igeo 的结果范围从 Igeo ≤ 0（未受污染）到 2 < Igeo < 3（中度至重度污染）。在灰尘和土壤样品中，Igeo 的 Zn、Pb、Cd、Ni 和 Cu 没有显示出污染；As 和 Cr 的 Igeo 在某些位置显示出中度污染，而 Mn 的 Igeo 显示出中度至重度污染。PLI 的结果范围从 PLI < 1（无污染）到 3 <PLI（极重污染）。