Heavy metals and soil microbes

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• 作者：Nafiu Abdu ; Aliyu A. Abdullahi ; Aisha Abdulkadir
• 关键词：Soil microbial biomass ; Metal pollution ; Bioremediation ; Biosorption ; Bioavailability ; Rhizosphere ; Anthropogenic ; Ecosystem ; Phytoremediation
• 刊名：Environmental Chemistry Letters
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：15
• 期：1
• 页码：65-84
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Environmental Chemistry; Ecotoxicology; Pollution, general; Analytical Chemistry; Geochemistry;
• 出版者：Springer International Publishing
• ISSN：1610-3661
• 卷排序：15

文摘

Heavy metal pollution is a global issue due to health risks associated with metal contamination. Although many metals are essential for life, they can be harmful to man, animal, plant and microorganisms at toxic levels. Occurrence of heavy metals in soil is mainly attributed to natural weathering of metal-rich parent material and anthropogenic activities such as industrial, mining, agricultural activities. Here we review the effect of soil microbes on the biosorption and bioavailability of heavy metals; the mechanisms of heavy metals sequestration by plant and microbes; and the effects of pollution on soil microbial diversity and activities. The major points are: anthropogenic activities constitute the major source of heavy metals in the environment. Soil chemistry is the major determinant of metal solubility, movement and availability in the soil. High levels of heavy metals in living tissues cause severe organ impairment, neurological disorders and eventual death. Elevated levels of heavy metals in soils decrease microbial population, diversity and activities. Nonetheless, certain soil microbes tolerate and use heavy metals in their systems; as such they are used for bioremediation of polluted soils. Soil microbes can be used for remediation of contaminated soils either directly or by making heavy metals bioavailable in the rhizosphere of plants. Such plants can accumulate 100 mg g−1 Cd and As; 1000 mg g−1 Co, Cu, Cr, Ni and 10,000 mg g−1 Pb, Mn and Ni; and translocate metals to harvestable parts. Microbial activity changes soil physical properties such as soil structure and biochemical properties such as pH, soil redox state, soil enzymes that influence the solubility and bioavailability of heavy metals. The concept of ecological dose (ED₅₀) and lethal concentration (LC₅₀) was developed in response to the need to easily quantify the influence of pollutants on microbial-mediated ecological processes in various ecosystems.