Lead (Pb

Next Article

Arsenic (As

Toxicity Effect by Heavy Metals as Pollutants on Fertile Soil

Gopal Mohanrao Kadam School of Chemical Sciences, S. R. T. M. University, Nanded, Maharashtra State, India-431606

Abstract: There are rising geologic and anthropogenic processes and as a result, now a days soils polluted by heavy metals have become more common and it is a problem across the globe. Soil polluted due to heavy metal can be freed from pollutants effectively by use of bioremediation process. It's a very well-known process and is used in situ, making it ideal to make soil free from pollutants as a part of crop establishment as well as restoration of soil which are being treated. Microorganisms as well as plants uses a variety of processes/methods to bioremediate the pollutants present in the different types of soils. Keywords: Heavy metal contamination, Remediation process, Soil pollutants, bioremediation process, soil pollutants

I. INTRODUCTION

In the atmosphere/environment around us, pollutants such as heavy metals can be found. In comparison and apart from the natural activities happening, as a consequence of almost every activity performed by human has the possibility of potential to generate heavy metals. The spread of heavy metals containing sewage sludge and the migration of these pollutants/contaminants into noncontaminated soil carried as dust and leachates, are two examples of existence that leads to contribute to ecosystem damage and contamination as overall. Plants that grow in these polluted soils are having less yield compared to non-polluted soil. Soils damaged due to heavy metals can be freed from pollutants more efficiently using mixing of microbes and plants, by the use of bioremediation technique. As a part to treat soil by the use of microbes and plants to remove pollutants/contaminants present in the soil by the process of bioremediation and to remove heavy metals from polluted soil is being adopted and now a days becoming more common. The pollution of soil caused due to heavy metals is very critical and having a global environmental issue. The experts in this area have estimation of about more than 20 million hectares of farmland in the asian country, China, has been polluted/contaminated, almost accounting to about 20% of the total land [1]. Cadmium (Cd) metal is being considered as one of the most phytotoxic in the metal pollutant because of its high mobility, especially in the soil which have low cation exchange capacity (CEC) and as well acidic pH, along with bioaccumulation in the lower organisms as it is easily being moved to higher trophic levels in the food chain [2]. The toxicity effect due to cadmium (Cd) metal as pollutant and its presence can have influence on plant survival, success of reproduction and migration [3]. As plants are considered to be sedentary in nature i.e., inactive because of lack of their ability to move actively to avoid pollutants/contaminants present in the environment, hence the chances of plants for their survival in the unfavorable surroundings is the mobilization of their defense mechanisms, and to evolution of them as tolerate genotype [4] Soil microorganisms in the rhizosphere of plants growing on metal-contaminated soils, both free-living and symbiotic soil microbes, can boost plant biomass production while also aiding the phytoremediation process. On the other hand, heavy metals have an effect on the growth, metabolism and morphology of soil microorganisms by functional disruption, the destruction of cell membrane integrity and protein denaturation. Traditionally, heavy-metal contaminated soils have been remedied by onsite management of excavation and with disposal to a landfill. The activity through disposal only relocates the problem caused due to contamination, as well as the risks are associated with carrying contaminated soil and as it migrates from the landfill into the surrounding ecosystem. There is an alternative as soil washing in comparison to excavation and landfill discarding as a part to clearing of polluted soil. As this process is quite expensive and produces a heavy metal-rich residue which will require further processes to treat the residue. The techniques used in the remediation of soil considering physico-chemical characteristics for the use of land, are tools for the growth of plants as all biological activities are being removed [5]. Many plant species have been successful in absorbing pollutants from soils, such as arsenic, chromium, cadmium, lead as well as different radionuclides i.e., radioactive nuclide/isotope. Phytoextraction, one of the categories considered for phytoremediation, can be used to eliminate heavy metals from the soil by utilization of the ability to ingest ions that are required for essential growth of plants such as copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), molybdenum (Mo), nickel (Ni) and zinc (Zn). The capacity of these metals to have uncertain biological activities (e.g., silver (Ag), cadmium (Cd), cobalt (Co), chromium (Cr), mercury (Hg), lead (Pb) and selenium (Se) may also have the possibility to accumulate. Heavy metals are originated from many sources [6]. The views as well as opinion expressed in this article are based on the literature/documents available to explain in simple ways however guidelines or documents from respective government agencies should be refereed for actual numerical data.