Inorganic Arsenic Analysis

A predominant source of inorganic arsenic in the world's population is in the consumption of common household rice (Norton et. al 2009). According to Food and Agriculture Organization of the United Nations (2013) rice is consumed across the world by over 3 billion people annually, which is estimated to be about 476 million tons of rice. Commonly sold rice contains high levels of inorganic arsenic, which can be harmful to people if consumed in large quantities. The acute minimal lethal dose of arsenic in adults is estimated to be 70 to 200 mg or 1 mg/kg/day (Laparra et al. 2005). Arsenic can be present in many forms, but the forms that is highly toxic to humans, and exist in rice, are is its inorganic form of Arsenate(AsV) and Arsenite(AsIII).

Phytoremediation is the cheap and effective process of using plants to reduce the number of contaminants embedded in soil. These plants cannot directly remove inorganic arsenic from rice, however they work on reducing the amount of inorganic arsenic that is available in the soil. A study by Ye et al. (2011) tested the soil from 5 different areas in the world that contain high levels of arsenic, the areas were respectively 1 sample from West Bengal, India (Nonaghata), 2 samples from Bangladesh (Faridpur and Sonargaon) and 2 samples from China (Chenzhou and Qiyang). Contamination of these soil samples come from factors such as geogenic pollution, contaminated ground water through irrigation and residual mining debris. The soil samples were separated into different pots and planted with an arsenic hyper accumulator known as Pteris vittata. The P. vittata acts as a sort of phototropic sponge that absorbs the inorganic arsenic from the soil before planting the rice reducing the uptake of inorganic arsenic in the seedlings of rice. Figure 1 shows the difference between the soil that was treated by the P. vittata(+Pv) and the one that was not (-Pv). The general trend suggests that there was a significant difference in the grain, the husk and the straw between the two tests. In all the soil samples the was a significant decrease from untreated soil to treated soil. This suggests that the implementation of P. vittata on soil with pre-existing contamination was successful. This phytoremediative method is an uncommon practice in large scale farming but is a plausible option that can be used to reduce the high inorganic arsenic concentrations of the soils in highly contaminated