Anthropogenic Environmental Pollution

The extent of anthropogenic environmental pollution in the developing world is well documented (Mattina et al., 2003). Among overall environmental pollution, water pollution is one of the major threat to public health especially in developing and under developed countries as drinking water quality in these countries is poorly managed and monitored (Mwegoha, 2008; Azizullah et al., 2011). Both surface and ground drinking water get contaminated with coli forms, toxic metals and pesticides. About 2.3 billion peoples are suffering from water related diseases worldwide (UNESCO, 2003). The presence of heavy metals (elements with an atomic density greater than 6 g/cm) is one of the most persistent pollutants present in water. Unlike other pollutants,

Increasing population, geological factors, rapid urbanization, agricultural developments, global markets, industrial development, industrialization and poor wastewater regulation have affected the quantity and the quality of water (Saleem, 2001; Farooq et al., 2006). Besides the indiscriminate disposal of industrial, municipal and domestic wastes in water channels, rivers, streams and lakes etc. are regarded as the documented source of water pollution (Kahlown and Majeed, 2003).

Asaolu (1998) reported that untreated domestic waste, discharges from industries, rapid deforestation and poor agricultural practices result in the soil erosion and leaching down of nutrients, pesticides and insecticides. An estimated 2 million tons of sewage and other effluents are discharged into the world's waters every day. In developing countries, the situation is worse where over 90% of raw sewage and 70% of untreated industrial wastes are dumped into surface water sources (Asaolu, 1998). Rapid industrialization in urban and Peri-urban areas and high living standards are mainly responsible for discharge of wastewater in the rivers and streams (Ashraf et al., 2010). Other sources of water pollution are sewage and waste water, marine dumping, industrial waste, radioactive waste, oil pollution, underground storage leakages, atmospheric deposition,

The term actually refers to a diverse collection of plant-based technologies that use either naturally occurring or genetically engineered plants for cleaning contaminated environments. The primary motivation behind the development of phytoremediative technologies is the potential for low-cost remediation (Ensley, 2000). Although the term, phytoremediation, is a relatively recent invention, the practice is not (Brooks, 1998a; Cunningham et al., 1997). Research using semi-aquatic plants for treating radionuclide-contaminated waters existed in Russia at the dawn of the nuclear era (Salt et al., 1995a). Some plants which grow on metalliferous soils have developed the ability to accumulate massive amounts of the indigenous metals in their tissues without exhibiting symptoms of toxicity (Baker and Brooks, 1989; Reeves and Brooks, 1983). Chaney (1983) was the first to suggest using these “hyperaccumulators” for the phytoremediation of metal polluted sites. However, hyperaccumulators were later believed to have limited potential in this area because of their small size and slow growth, which limit the speed of metal removal (Cunningham et al., 1995; Ebbs et al., 1997). By definition, a hyperaccumulator must accumulate at least 1000 μgAg-1 of Co, Cu, Cr, Pb, or Ni, or 10,000 μgAg-1 (i.e. 1%) of Mn or Zn in the dry