The main threats to human health from heavy metals are associated with exposure to lead, cadmium, mercury and arsenic. The resultsrevealed that heavy metals brought about significant reductionsin both parameters, cd being the most toxic metal. The term heavy metals is sometimes used to suggest pollution and toxic effects. Alongside these mechanisms, the noxious health effects of these heavy metals are discussed. Effect of heavy metals in plants of the genus brassica. Unprecedented bioaccumulation and biomagnification of heavy metals hms in the environment have become a dilemma for all living organisms including plants. This results in accumulation of metals in plant parts having secondary metabolites, which is responsible for a. Review article toxicity, mechanism and health effects of. Hms at toxic levels have the capability to interact with several vital cellular biomolecules such as nuclear proteins and dna, leading to excessive augmentation of reactive oxygen species ros.
The toxicity of heavy metals can be removed bioremediation or phytoremediation. Heavy metal contamination of soil results from anthropogenic as well as. This series of technical notes examines the urban activities that cause soil degradation, and the management practices that protect. 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. The oldest leaves of metal exposed plants exhibit the highest metal content ernst 1998.
Consequently, the metal availability to plants is quite important when assessing the effect of soil contamination on plant metal uptake tokalioglu and kartal 2003. One of the factors that are polluting the nature of the heavy metal ve getative organs of plants macroscopic, microscopic and physiological effect. Heavy metals are persistent in nature, therefore get accumulated in soils and plants. Conclusions based on the results, we concluded that the seed germination of the alfalfa plant cultivar. Damage to brassica plants is due to direct heavy metal effects or to induced oxidative stress. Cultivation of crops on contaminated sites may result in both growth inhibition and tissue accumulation of heavy metals with resulting possible risks to humans health. Heavy metals in industrial wastewater include lead, chromium, mercury, uranium, selenium, zinc, arsenic, cadmium, silver, gold, and nickel. Phytoextraction the use of plants for hm removal from the contaminated matrix soil and water through their uptake into the harvestable parts of. The biota may require some of these elements in trace quantities but at higher concentrations there may be toxicity problems. All heavy metals were below the standard limits with the values were in the range of commonly found heavy metal concentrations in plants as stated by misra and mani 62, and nagajyoti et. Thereby, they run a complex system consisting of uptakeefflux.
The use of phytoremediation technology for heavy metal contaminated soils has been widely studied in recent years cristaldi et al. The objectives of this paper are to discuss the potential of phytoremediation technique on treating heavy metal contaminated side, to provide a brief view about heavy metals uptake mechanisms by plant, to give some description about the performance of several types of plants to uptake heavy metals and to describe about the fate of heavy metals. Heavy metals enter the surroundings by natural means and through human activities. Toxicity, mechanism and health effects of some heavy metals. Effects of metals on enzyme activity in plants assche. Boron is an essential nutrient for plants and some microorganisms and has a function in reproduction and development and possibly carbohydrate. Although reports exist over effect of the metal toxicity on plants, very few reports exist on how heavy metals affect seed physiology. Toxic heavy metals considered as phytotoxic agents to plants that affect the plant morphological and physiological processes such as lower. Assisting phytoremediation of heavy metals using chemical. Effects of heavy metals on plants and resistance mechanisms. Monitoring of selected heavy metals uptake by plants and soils in. It is a widely accepted method that is mostly carried out in situ.
Cadmium cd, a nonessential metal element for people and plants, is widely present in soils in europe, china. The presence of metals in the leaves can hamper plant metabolism and growth even at very low concentrations. Heavy metal accumulation in the leaves, stem and root. Heavy metal toxicity has proven to be a major threat and there are several health risks associated with it. These heavy metals have severe effects on plants, animals, humans and ultimately on environment. Mechanism and health effects of heavy metal toxicity in. Biochar has been used to reduce the mobility and availability of heavy metals in contaminated paddy soils. Phytoextraction is the most common method of phyto remediation used for treatment of heavy metal polluted soils.
The essential heavy metals exert biochemical and physiological functions in plants and. A pot study was conducted to investigate the toxiceffects of certain heavy metals on the plant growth and grainyield of wheat triticum aestivum l. On the other hand, plants have their own resistance mechanisms against toxic effects and for detoxifying heavy metal pollution. The plant biomass extracted heavy metals from the sewage sludge more intensively than from the cellulose production waste. In this work the effect of the heavy metals as hg, cd, zn and tl on tomato growth is presented. Heavy metals are significant environmental pollutants and their toxicity is a problem of increasing significance for ecological, evolutionary, nutritonal and environmental reasons. The aim of this present study was to determine the effects of heavy metals cd, cu and zn on plant growth, tissue concentration and examine their uptake by sunflower in soil. Pdf effect of heavy metals on plant growth and ability. Heavy metals, production and use, human exposure, toxicity. Heavy metals contamination and what are the impacts on. The role of heavy metal transporters is now much clearer in these plants and they seem to have a fundamental importance in the tolerance of brassica species to different heavy metals. Plants have their own resistance mechanisms against toxic effects and for detoxifying heavy metal pollution. Pdf effects of heavy metals on soil, plants, human. Pdf wastes are the major source of soil pollution originates from mining, chemical, metal processing industries, and other allied industries.
The cellulose production waste and municipal sewage sludge increased the heavy metal uptake by the plant mixture. The effect of palm oil mill effluent final discharge on. Effect of biochar from peanut shell on speciation and. Lead targets multiple organs in the body due to its systemic toxicity which can cause. The high concentration of heavy metals in soils is re flected by higher concentrations of metals. The effects of heavy metals on plants resulted in growth inhibition, structure damage, a decline of physiological and biochemical activities, as well as of the function of plants 1. Marinova 2 1 uludag university, faculty of agriculture, department of soil science, bursa 16059, turkey 2 nikola poushkarov institute of soil science and. A pot experiment was carried out to analyze the effects of peanut shell biochar pbc on the speciation and phytoavailability of pb and zn in contaminated acidic paddy soil using rice oryza sativa l. Heavy metals are generally not removable even after the treatment of wastewater at sewage treatment plants and thus, cause risk of heavy metal contamination of the soil. The chemical form of heavy metals in soil solution is dependant of the metal concerned, ph and the presence of other ions.
Eight common heavy metals are discussed in this brief. In plants, the toxicity of heavy metals may cause chlorosis, necrosis, changes in plants phenotype, and damage to fundamental organs etc. The impact of the heavy metals on aquatic organisms is due to the movements of pollutants from various diffuse or point. Heavy metals are kept under environmental pollutant category due to their toxic effects on plants, animals and human being. Heavy metals are natural constituents of the earths crust, but indiscriminate human activities have drastically altered their geochemical cycles and biochemical balance. Metal contamination issues are becoming increasingly common in india and elsewhere, with many documented cases of metal toxicity in mining industries, foundries, smelters, coalburning power plants and agriculture. Excess of metals may produce some common effects of individual metals on different plants i.
Adaptation strategies of plants against heavy metal toxicity. Heavy metal accumulation showed increase generally in fall. Metaanalysis of the copper, zinc, and cadmium absorption. Pdf effect on plant growth and heavy metal accumulation. Its effect on the human body can be both acute and chronic depending on dose and exposure scenarios. Heavy metal pollution in soil and water is a global environmental concern.
The effect of cellulose production waste and municipal. Human health effects of heavy metals introduction heavy metals are individual metals and metal compounds that can impact human health. Toxic effects of heavy metals on human health and plants. Heavy metals toxicity and the environment ncbi nih.
Hms can be classified as either essential or nonessential. Pdf effects of heavy metals on plants and resistance. Influence of soil properties on the accumulation of heavy. In the case of znii, the data found in this study indicate that this heavy metal has positive effects on the growth of the alfalfa plants, even at moderately high concentrations.
Bioremediation is an effective method of treating heavy metal polluted soils. Under metal stress, plants exhibit a thickening of root tips and a decreased root hair density punz and sieghardt 1992. Heavy metal stress and some mechanisms of plant defense. Barua b, jana s 1986 effect of heavy metals on dark induced changes in hill action activty, chlorophyll and protein contents, dry matter and tissue permeability in detached spinacia oleracea l. Their multiple industrial, domestic, agricultural, medical and technological applications have led to their wide distribution in the environment. Effects of heavy metals on soil, plants, human health and aquatic life. Uptake of heavy metals by plants and subsequent accumulation along the food chain is a potential threat to animal and. Children and heavy metals to define the spectrum of heavy metals others than lead and mercury with adverse effects on human health to describe the epidemiology of adverse effects of heavy metals arsenic, cadmium, copper and thallium in children to describe sources and routes of exposure of children to those heavy metals. Soils polluted with heavy metals have become common across the globe due to increase in geologic and anthropogenic activities. Dietary intake of many heavy metals through consumption of plants has long term detrimental effects on human health. Effect of metal toxicity on plant growth and metabolism. The heavy metal accumulation in crops may cause serious disorders in plants as well as in human beings. Department of biology, sciences faculty, islamic azad university, mashhad branch, mashhad, iran. Pdf effects of heavy metals toxicity on plants and.
Heavy metals distribution, sources, and ecological risk. Heavy metals contamination and what are the impacts on living organisms. Various sources of heavy metals include soil erosion, natural weathering. Effects on human health lead is a toxic heavy metal even at very low levels of exposure in humans. The effect of lead on plants in terms of growing and. Frequently reported observations include stunted growth, reduced. Impact of heavy metals on photosynthesis springerlink. They reduces productivity, bring stunting in growth and loss in chlorophyll chlorosis and protein contents in higher aquatic plants these metals are incorporated permanently in plants and then are passed on to animals and human beings.
Among the analyzed heavy metals, the highest phytoremediation was recorded for ni 30%, followed by. Heavy metals are naturally occurring elements that have a high atomic weight and a density at least 5 times greater than that of water. Effect of heavy metals on plants linkedin slideshare. Basal heavy metal tolerance is presumably found in all plant species. Plants growing on these soils show a reduction in growth, performance, and yield. Heavy metals, such as cadmium, copper, lead, chromium and mercury are major environmental pollutants, particularly in areas with high anthropogenic pressure. Some of the major controls on the bioavailability of metals in surface water and soil and data concerning potentially hazardous metals are described below. To study the effects of heavy metals on plants and mechanisms of resistance, one must select crop cultivars andor plants for removing heavy metals from soil and water. One of phytoremediation categories, phytoextraction, can be used to remove heavy metals from soil using its ability to uptake metals which are essential for plant. Peanut shell biochar was applied to an acidic paddy.
89 828 1089 753 201 1469 292 605 722 1172 6 1183 1322 1053 49 425 168 533 1096 1135 1113 608 281 226 1414 21 434 699 853 1164 432 1457 1542 1456 363 881 1320 983 562 629 853 12 1343