Udiba Udiba Ugumanim, Antai Ekpo Eyo, Akpan Ekom Robert
Department of Zoology and Environmental Biology, University of Calabar, Calabar, Nigeria.
Institute of Oceanography, University of Calabar, Calabar, Nigeria.
J Health Pollut. 2020 Jan 22;10(25):200301. doi: 10.5696/2156-9614-10.25.200301. eCollection 2020 Mar.
Environmental contamination by lead (Pb) and other toxic metals is of significant environmental and human health concern. Heavy metals are not readily eliminated by degradation, and thus remediation of contaminated media (soil, sediment and water/sludge) requires the outright removal or cleanup of these metals. Evaluation of the performance and cost efficiency of various remediation methods has led to the development of bioremediation as an inexpensive, innovative and environmentally friendly cleanup strategy.
The present study was designed to assess the Pb remediation potential of wild Senna obtusifolia (Sicklepod), in Dareta Village, Zamfara, Nigeria.
Soil and Senna obtusifolia samples were collected from established plots and Pb content was determined using a Shimadzu atomic absorption spectrophotometer (model AA-6800, Japan) after wet digestion.
The mean concentrations of Pb (mg/kg) in soil, roots, stems and leaves, respectively, were 130.68±5.2, 61.33±17.86, 66.64±18.10 and 173.39±13.73 for plot 1, 287.84±6.5, 69.42±11.62, 123.4±3.67 and 294.28±4.38 for plot 2, 315.73±4.13, 68.42±10.22, 86.89±6.08 and 290.61±7.47 for plot 3, 396.86±5.48, 91.64±2.87, 150.58±2.21 and 282.53±5.69 for plot 4 and 264.23±8.02, 72.71±2.18, 124.60±2.27 and 282.40±3.79 for plot 5. Average values for the translocation factor, bioaccumulation factor and bioconcentration factor were 3.65±0.66, 1.01±0.23 and 0.29±0.10, respectively.
Soil Pb levels in the present study were found to be within the United States Environmental Protection Agency (USEPA) standards and the Dutch Intervention Values for Pb in soil. Lead content of Senna obtusifolia leaves was found to be higher than the Pb content of the stem and root, indicating relatively low restriction and the efficiency of internal transport of the toxic metal from the roots towards the aerial parts. High translocation and bioaccumulation factors indicate that the plant has vital characteristics for phytoextraction of Pb. The mean Pb concentration of Senna obtusifolia leaves was found to be far above Codex general standards and the European Union (EU) maximum levels for Pb in leafy vegetables.
The study concludes that wild Senna obtusifolia has significant characteristics for phytoextraction of Pb and that consumption of Senna obtusifolia leaves from the study area would pose a serious risk of Pb intoxication.
The authors declare no competing financial interests.
铅（Pb）和其他有毒金属对环境的污染是重大的环境和人类健康问题。重金属不易通过降解消除，因此对受污染介质（土壤、沉积物和水/污泥）的修复需要彻底去除或清理这些金属。对各种修复方法的性能和成本效益的评估导致了生物修复作为一种廉价、创新且环保的清理策略的发展。
本研究旨在评估尼日利亚赞法拉州达雷塔村野生番泻叶（决明）对铅的修复潜力。
从已建立的地块采集土壤和番泻叶样本，经湿法消解后，使用岛津原子吸收分光光度计（型号AA - 6800，日本）测定铅含量。
地块1土壤、根、茎和叶中铅的平均浓度（mg/kg）分别为130.68±5.2、61.33±17.86、66.64±18.10和173.39±13.73；地块2分别为287.84±6.5、69.42±11.62、123.4±3.67和294.28±4.38；地块3分别为315.73±4.13、68.42±10.22、86.89±6.08和290.61±7.47；地块4分别为396.86±5.48、91.64±2.87、150.58±2.21和282.53±5.69；地块5分别为264.23±8.02、72.71±2.18、124.60±2.27和282.40±3.79。转运系数、生物累积系数和生物富集系数的平均值分别为3.65±0.66、1.01±0.23和0.29±0.10。
本研究中土壤铅含量在美国环境保护局（USEPA）标准和荷兰土壤铅干预值范围内。发现番泻叶叶片中的铅含量高于茎和根中的铅含量，表明该有毒金属从根部向地上部分的内部运输限制相对较低且效率较高。高转运和生物累积系数表明该植物具有用于铅植物提取的重要特性。发现番泻叶叶片的平均铅浓度远高于食品法典通用标准和欧盟叶菜类蔬菜中铅的最高限量。
该研究得出结论，野生番泻叶具有用于铅植物提取的显著特性，并且食用研究区域的番泻叶叶片会带来严重的铅中毒风险。
作者声明不存在相互竞争的财务利益。
