Heavy metals, occurrence and toxicity for plants: a review
TL;DR: In this article, the range of heavy metals, their occurrence and toxicity for plants, and their effects on the ecosystem is discussed, where the authors focus mainly on zinc, cadmium, copper, mercury, chromium, lead, arsenic, cobalt, nickel, manganese and iron.
Abstract: Metal contamination issues are becoming increasingly common in India and elsewhere, with many documented cases of metal toxicity in mining industries, foundries, smelters, coal-burning power plants and agriculture. Heavy metals, such as cadmium, copper, lead, chromium and mercury are major environmental pollutants, particularly in areas with high anthropogenic pressure. Heavy metal accumulation in soils is of concern in agricultural production due to the adverse effects on food safety and marketability, crop growth due to phytotoxicity, and environmental health of soil organisms. The influence of plants and their metabolic activities affects the geological and biological redistribution of heavy metals through pollution of the air, water and soil. This article details the range of heavy metals, their occurrence and toxicity for plants. Metal toxicity has high impact and relevance to plants and consequently it affects the ecosystem, where the plants form an integral component. Plants growing in metal-polluted sites exhibit altered metabolism, growth reduction, lower biomass production and metal accumulation. Various physiological and biochemical processes in plants are affected by metals. The contemporary investigations into toxicity and tolerance in metal-stressed plants are prompted by the growing metal pollution in the environment. A few metals, including copper, manganese, cobalt, zinc and chromium are, however, essential to plant metabolism in trace amounts. It is only when metals are present in bioavailable forms and at excessive levels, they have the potential to become toxic to plants. This review focuses mainly on zinc, cadmium, copper, mercury, chromium, lead, arsenic, cobalt, nickel, manganese and iron.
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TL;DR: This review gives details about some heavy metals and their toxicity mechanisms, along with their health effects.
Abstract: Heavy metal toxicity has proven to be a major threat and there are several health risks associated with it. The toxic effects of these metals, even though they do not have any biological role, remain present in some or the other form harmful for the human body and its proper functioning. They sometimes act as a pseudo element of the body while at certain times they may even interfere with metabolic processes. Few metals, such as aluminium, can be removed through elimination activities, while some metals get accumulated in the body and food chain, exhibiting a chronic nature. Various public health measures have been undertaken to control, prevent and treat metal toxicity occurring at various levels, such as occupational exposure, accidents and environmental factors. Metal toxicity depends upon the absorbed dose, the route of exposure and duration of exposure, i.e. acute or chronic. This can lead to various disorders and can also result in excessive damage due to oxidative stress induced by free radical formation. This review gives details about some heavy metals and their toxicity mechanisms, along with their health effects.
3,580 citations
Cites background from "Heavy metals, occurrence and toxici..."
...Heavy metals are significant environmental pollutants and their toxicity is a problem of increasing significance for ecological, evolutionary, nutritional and environmental reasons (Jaishankar et al., 2013; Nagajyoti et al., 2010)....
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Book•
01 Jan 2013
TL;DR: In this article, the authors defined the sources of heavy metals and metalloids in Soils and derived methods for the determination of Heavy Metals and Metalloids in soil.
Abstract: Preface.- Contributors.- List of Abbreviations.- Section 1: Basic Principles: Introduction.-Sources of Heavy Metals and Metalloids in Soils.- Chemistry of Heavy Metals and Metalloids in Soils.- Methods for the Determination of Heavy Metals and Metalloids in Soils.- Effects of Heavy Metals and Metalloids on Soil Organisms.- Soil-Plant Relationships of Heavy Metals and Metalloids.- Heavy Metals and Metalloids as Micronutrients for Plants and Animals.-Critical Loads of Heavy Metals for Soils.- Section 2: Key Heavy Metals And Metalloids: Arsenic.- Cadmium.- Chromium and Nickel.- Cobalt and Manganese.- Copper.-Lead.- Mercury.- Selenium.- Zinc.- Section 3: Other Heavy Metals And Metalloids Of Potential Environmental Significance: Antimony.- Barium.- Gold.- Molybdenum.- Silver.- Thallium.- Tin.- Tungsten.- Uranium.- Vanadium.- Glossary of Specialized Terms.- Index.
1,684 citations
TL;DR: In this article, a comprehensive review of the environmental chemistry and ecotoxicology of hazardous heavy metals and metalloids is presented, focusing on their environmental persistence, toxicity for living organisms, and bioaccumulative potential.
Abstract: Heavy metals are well-known environmental pollutants due to their toxicity, persistence in the environment, and bioaccumulative nature. Their natural sources include weathering of metal-bearing rocks and volcanic eruptions, while anthropogenic sources include mining and various industrial and agricultural activities. Mining and industrial processing for extraction of mineral resources and their subsequent applications for industrial, agricultural, and economic development has led to an increase in the mobilization of these elements in the environment and disturbance of their biogeochemical cycles. Contamination of aquatic and terrestrial ecosystems with toxic heavy metals is an environmental problem of public health concern. Being persistent pollutants, heavy metals accumulate in the environment and consequently contaminate the food chains. Accumulation of potentially toxic heavy metals in biota causes a potential health threat to their consumers including humans. This article comprehensively reviews the different aspects of heavy metals as hazardous materials with special focus on their environmental persistence, toxicity for living organisms, and bioaccumulative potential. The bioaccumulation of these elements and its implications for human health are discussed with a special coverage on fish, rice, and tobacco. The article will serve as a valuable educational resource for both undergraduate and graduate students and for researchers in environmental sciences. Environmentally relevant most hazardous heavy metals and metalloids include Cr, Ni, Cu, Zn, Cd, Pb, Hg, and As. The trophic transfer of these elements in aquatic and terrestrial food chains/webs has important implications for wildlife and human health. It is very important to assess and monitor the concentrations of potentially toxic heavy metals and metalloids in different environmental segments and in the resident biota. A comprehensive study of the environmental chemistry and ecotoxicology of hazardous heavy metals and metalloids shows that steps should be taken to minimize the impact of these elements on human health and the environment.
1,382 citations
TL;DR: The sources of toxic heavy metals are discussed, the groups of microorganisms with biosorbent potential for heavy metal removal are described and the use of microbial biosorbents is eco-friendly and cost effective.
Abstract: Persistent heavy metal pollution poses a major threat to all life forms in the environment due to its toxic effects. These metals are very reactive at low concentrations and can accumulate in the food web, causing severe public health concerns. Remediation using conventional physical and chemical methods is uneconomical and generates large volumes of chemical waste. Bioremediation of hazardous metals has received considerable and growing interest over the years. The use of microbial biosorbents is eco-friendly and cost effective; hence, it is an efficient alternative for the remediation of heavy metal contaminated environments. Microbes have various mechanisms of metal sequestration that hold greater metal biosorption capacities. The goal of microbial biosorption is to remove and/or recover metals and metalloids from solutions, using living or dead biomass and their components. This review discusses the sources of toxic heavy metals and describes the groups of microorganisms with biosorbent potential for heavy metal removal.
1,035 citations
Cites background from "Heavy metals, occurrence and toxici..."
...The standard for soil, as established by the Indian standards for heavy metals, is 3–6, 135–270, 75–150, 250–500, and 300–600 mg/kg for Cd, Cu, Ni, Pb, and Zn respectively [5]....
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...The toxicity of heavy metals in plants varies, depending on the plant species, specific metal involved, concentration of metal, chemical form of metal, and soil composition and pH [5]....
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...Lead Coal combustion, electroplating, manufacturing of batteries, mining, paint, pigments Anorexia, chronic nephropathy, damage to neurons, high blood pressure, hyperactivity, insomnia, learning deficits, reduced fertility, renal system damage, risk factor for Alzheimer’s disease, shortened attention span Affects photosynthesis and growth, chlorosis, inhibit enzyme activities and seed germination, oxidative stress Denatures nucleic acid and protein, inhibits enzymes activities and transcription [5,24,34,35]...
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...Copper Copper polishing, mining, paint, plating, printing operations Abdominal pain, anemia, diarrhea, headache, liver and kidney damage, metabolic disorders, nausea, vomiting Chlorosis, oxidative stress, retard growth Disrupt cellular function, inhibit enzyme activities [2,5,24,31]...
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TL;DR: This review summarizes various tolerance strategies of plants under heavy metal toxicity covering the role of metabolites (metabolomics), trace elements (ionomics), transcription factors (transcriptomics), various stress-inducible proteins (proteomics) as well as therole of plant hormones.
Abstract: Heavy metal contamination of soil and water causing toxicity/stress has become one important constraint to crop productivity and quality. This situation has further worsened by the increasing population growth and inherent food demand. It have been reported in several studies that counterbalancing toxicity, due to heavy metal requires complex mechanisms at molecular, biochemical, physiological, cellular, tissue and whole plant level, which might manifest in terms of improved crop productivity. Recent advances in various disciplines of biological sciences such as metabolomics, transcriptomics, proteomics etc. have assisted in the characterization of metabolites, transcription factors, stress-inducible proteins involved in heavy metal tolerance, which in turn can be utilized for generating heavy metal tolerant crops. This review summarizes various tolerance strategies of plants under heavy metal toxicity, covering the role of metabolites (metabolomics), trace elements (ionomics), transcription factors (transcriptomics), various stress-inducible proteins (proteomics) as well as the role of plant hormones. We also provide a glance at strategies adopted by metal accumulating plants also known as “metallophytes”.
820 citations
Cites background from "Heavy metals, occurrence and toxici..."
...Once inside the cell, heavy metals alter metabolism that results into a reduction of growth and lower biomass accumulation (Nagajyoti et al., 2010)....
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...…blocks functional groups of metabolically important molecules, hormonal balance, nutrient assimilation, protein synthesis, and DNA replication (Nagajyoti et al., 2010; Yadav, 2010; Keunen et al., 2011; He et al., 2012; Hossain et al., 2012a,b; Silva, 2012; Wani et al., 2012; Singh et al.,…...
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References
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Book•
01 Jan 1986
TL;DR: This chapter discusses the relationship between Mineral Nutrition and Plant Diseases and Pests, and the Soil-Root Interface (Rhizosphere) in Relation to Mineral Nutrition.
Abstract: Nutritional Physiology: Introduction, Definition, and Classification of Mineral Nutrients. Ion Uptake Mechanisms of Individual Cells and Roots: Short Distance Transport. Long-Distance Transport in the Xylem and Phloem and its Regulation. Uptake and Release of Mineral Elements by Leaves and Other Aerial Plant Parts. Yield and the Source-Sink Relationships. Mineral Nutrition and Yield Response. Nitrogen Fixation. Functions of Mineral Nutrients: Macronutrients. Function of Mineral Nutrients: Micronutrients. Beneficial Mineral Elements. Relationship between Mineral Nutrition and Plant Diseases and Pests. Diagnosis of Deficiency and Toxicity of Mineral Nutrients. Plant-Soil Relationships: Nutrient Availability in Soils. Effect of Internal and External Factors on Root Growth and Development. The Soil-Root Interface (Rhizosphere) in Relation to Mineral Nutrition. Adaptation of Plants to Adverse Chemical Soil Conditions. References. Subject Index.
18,276 citations
"Heavy metals, occurrence and toxici..." refers background in this paper
...The chlorosis may arise partly from an induced iron (Fe) deficiency as hydrated Zn and Fe ions have similar radii (Marschner 1986)....
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...2 ions have similar radii (Marschner 1986)....
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Book•
01 Jan 1986
TL;DR: In this article, the authors discuss the relationship between mineral nutrition and plant diseases and pests, and diagnose deficiency and toxicity of mineral nutrients in leaves and other aerial parts of a plant.
Abstract: Nutritional Physiology: Introduction, Definition, and Classification of Mineral Nutrients. Ion Uptake Mechanisms of Individual Cells and Roots: Short Distance Transport. Long-Distance Transport in the Xylem and Phloem and its Regulation. Uptake and Release of Mineral Elements by Leaves and Other Aerial Plant Parts. Yield and the Source-Sink Relationships. Mineral Nutrition and Yield Response. Nitrogen Fixation. Functions of Mineral Nutrients: Macronutrients. Function of Mineral Nutrients: Micronutrients. Beneficial Mineral Elements. Relationship between Mineral Nutrition and Plant Diseases and Pests. Diagnosis of Deficiency and Toxicity of Mineral Nutrients. Plant-Soil Relationships: Nutrient Availability in Soils. Effect of Internal and External Factors on Root Growth and Development. The Soil-Root Interface (Rhizosphere) in Relation to Mineral Nutrition. Adaptation of Plants to Adverse Chemical Soil Conditions. References. Subject Index.
16,025 citations
TL;DR: The chapter discusses the metabolism of transition metals, such as iron and copper, and the chelation therapy that is an approach to site-specific antioxidant protection.
Abstract: Publisher Summary This chapter discusses the role of free radicals and catalytic metal ions in human disease. The importance of transition metal ions in mediating oxidant damage naturally leads to the question as to what forms of such ions might be available to catalyze radical reactions in vivo . The chapter discusses the metabolism of transition metals, such as iron and copper. It also discusses the chelation therapy that is an approach to site-specific antioxidant protection. The detection and measurement of lipid peroxidation is the evidence most frequently cited to support the involvement of free radical reactions in toxicology and in human disease. A wide range of techniques is available to measure the rate of this process, but none is applicable to all circumstances. The two most popular are the measurement of diene conjugation and the thiobarbituric acid (TBA) test, but they are both subject to pitfalls, especially when applied to human samples. The chapter also discusses the essential principles of the peroxidation process. When discussing lipid peroxidation, it is essential to use clear terminology for the sequence of events involved; an imprecise use of terms such as initiation has caused considerable confusion in the literature. In a completely peroxide-free lipid system, first chain initiation of a peroxidation sequence in a membrane or polyunsaturated fatty acid refers to the attack of any species that has sufficient reactivity to abstract a hydrogen atom from a methylene group.
5,033 citations
"Heavy metals, occurrence and toxici..." refers background in this paper
...Although these molecules are not very reactive, they can form hydroxyl radicals (– OH), which are probably responsible for most of the oxidative damage in biological systems (Cadenas 1989; Halliwell and Cutteridge 1990)....
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...OH), which are probably responsible for most of the oxidative damage in biological systems (Cadenas 1989; Halliwell and Cutteridge 1990)....
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TL;DR: It is proposed that, above all in response to acute cadmium stress, various mechanisms might operate both in an additive and in a potentiating way, and a holistic and integrated approach seems to be necessary in the study of the response of higher plants to Cadmium.
2,189 citations
"Heavy metals, occurrence and toxici..." refers background in this paper
...Plants grown in soil containing high levels of Cd show visible symptoms of injury reflected in terms of chlorosis, growth inhibition, browning of root tips and finally death (Sanita di Toppi and Gabbrielli 1999; Wojcik and Tukiendorf 2004; Mohanpuria et al. 2007; Guo et al. 2008)....
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TL;DR: Biological mechanisms of toxic metal uptake, translocation and resistance as well as strategies for improving phytoremediation are also discussed.
Abstract: Toxic metal pollution of waters and soils is a major environmental problem, and most conventional remediation approaches do not provide acceptable solutions. The use of specially selected and engineered metal-accumulating plants for environmental clean-up is an emerging technology called phytoremediation. Three subsets of this technology are applicable to toxic metal remediation: (1) Phytoextraction--the use of metal-accumulating plants to remove toxic metals from soil; (2) Rhizofiltration--the use of plant roots to remove toxic metals from polluted waters; and (3) Phytostabilization--the use of plants to eliminate the bioavailability of toxic metals in soils. Biological mechanisms of toxic metal uptake, translocation and resistance as well as strategies for improving phytoremediation are also discussed.
2,183 citations
"Heavy metals, occurrence and toxici..." refers background in this paper
...Cadmium effects on plants The regulatory limit of cadmium (Cd) in agricultural soil is 100 mg/kg soil (Salt et al. 1995)....
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...The regulatory limit of cadmium (Cd) in agricultural soil is 100 mg/kg soil (Salt et al. 1995)....
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