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.

Heavy metals, occurrence and toxicity for plants: a review

The science of the total environment

Chromium toxicity in plants.

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.

Heavy metals in soils : trace metals and metalloids in soils and their bioavailability

Remediation of heavy metal(loid)s contaminated soils - To mobilize or to immobilize?

Accumulation properties of As, Cd, Cu, Pb and Zn by four wetland plant species growing on submerged mine tailings

Influence of temperature and salinity on heavy metal uptake by submersed plants.

Heavy metals are natural elements that are found at various high background levels (Table 1.1) at different places throughout the world, due to various concentrations in the bedrock. Thus, for example, Ni, Cr and Co are abundant in serpentine soils whereas Zn, Pb and Cd are high in calamine soils. Heavy metals are persistent and cannot be deleted from the environment. Thus, a problem arises when their availability is high due to high background levels or to human activity.

Metal Availability and Bioconcentration in Plants

Differences in uptake and tolerance to heavy metals in Salix from unpolluted and polluted areas

Willow is shown to be able to accumulate high levels of heavy metal ions such as cadmium and zinc. The properties of willow to be used in phytoextraction therefore have been studied. In this article, results from different studies on heavy metals and willow have been used to demonstrate the capacity and possibility of using Salix in phytoextraction.

Maria Greger

Papers

Accumulation properties of As, Cd, Cu, Pb and Zn by four wetland plant species growing on submerged mine tailings

Influence of temperature and salinity on heavy metal uptake by submersed plants.

Metal Availability and Bioconcentration in Plants

Differences in uptake and tolerance to heavy metals in Salix from unpolluted and polluted areas

Use of willow in phytoextraction.