Soil bioremedation



For instance, a recent report by Wu and Yu (2011) indicated that the issue of environmental pollution in China has reached an alarming extent. Specifically, the article reported that as of 2011, one-sixth of China’s agricultural land has been contaminated with mercury, cadmium, copper, and other heavy metals (Wu and Yu, 2011). According to the Chinese Academy of Agricultural Engineering, this fraction of land is equivalent to approximately 20 million hectares, with the industrialized regions being more critically affected (Wu and Yu, 2011). Heavy metal-contaminated grounds have been shown to greatly affect the floral, faunal, and microbial communities (Lukkari et al., 2004. Agoramoorthy et al., 2006. Chen et al., 2007). In a study conducted by McGrath et al. (2001), it was found that exposure to toxic metals significantly reduced microbial diversity and other biologically-mediated soil activities. This alteration in the microbial composition, according to Elsgaard et al. (2001) may negatively affect recycling of plant nutrients, regulation of plant pest and plant growth, and maintenance of soil structure. Also, pollutants from the soil could accumulate in plants and can then be transferred to higher trophic levels in the food chain, posing health hazards to humans (Notten et al., 2005). Furthermore, the effects of soil pollution are not only confined to the terrestrial compartment of the ecosystem. It can also influence the integrity and dynamics of aquatic and marine systems (Cardellicchio et al., 2006. Vorosmarty et al., 2010). By virtue of geoweathering processes, hydrocarbons, organophosphates, and metal contaminants deposited in the ground could leach down the water table and redistribute in surrounding streams, lakes, and other bodies of water (Chen et al., 2007). Given the tremendous threats soil pollution poses to the environment and to human population, the need to control soil contamination or neutralize its toxic effects and the institution of rehabilitation in areas previously affected by this problem is indeed necessary. Bioremediation, a technology that makes use of living organisms to treat polluted areas, is one of the most commonly used strategies to rehabilitate contaminated soils (Nasu and Iwamoto, 2001. Obbard et al., 2005. Umrania, 2006. Luo et al., 2010). Technically, bioremediation focuses on enhancing the natural biodegradation process at a rate that significantly increases the removal of contaminants (Calvo et al., 2009). One commonly employed bioremediation strategy is to supply the polluted environment with nutrients like nitrogen to hasten the process of degradation (Nasu and Iwamoto, 2001. Calvo et al., 2009). Another popular method is to directly introduce organisms with desired capabilities to the contaminated areas in the hope of speeding up biodegradation (Nasu and Iwamoto, 2001). Hence, by exploiting the biological processes inherent to plants or bacteria, the clean-up of environmental pollutants like hydrocarbons, lead, cadmium, and the like could be made possible (Obbard et al., 2011. Luo et al., 2010­). However, the development of enhanced capabilities for degradation or accumulation of organic and heavy metal contaminants