Impacts of Gold Mining on Rice Production in the Anum Valley of Ghana

Abstract

This study assessed the concentrations of arsenic and iron in paddy soil and rice grain samples collected from the Nobewam and Odumase paddy field sites in the Anum Valley of Ghana, as a means of determining the impacts of gold mining activities in the area on rice production. The arsenic content of rice grains from the Anum Valley paddy fields was compared to that in rice grains of the same variety harvested from three non-impacted paddy fields (control sites) in other parts of Ghana. The study findings indicated that soils in the Odumase paddy fields, which are located closer to the gold mining site, were significantly more impacted by mining pollution than soils in the Nobewam paddy fields. Arsenic concentration in the Nobewam paddy soils ranged from 0.6 to 76.1 mg/kg with a mean of 8.3 mg/kg, while that in the Odumase paddy soils ranged from 5.3 to 106.2 mg/kg with a mean of 41.1 mg/kg. Despite the significant difference in mean soil arsenic content, there was no significant difference in the arsenic content of rice grains harvested from the two Anum Valley paddy sites ( i.e . Nobewam and Odumase). There was also no significant difference between the two Anum Valley paddy sites with respect to soil iron concentration. The regression equation for a graph of soil arsenic against soil iron (As = 70.0 Fe – 37.7) was, however, highly significant (P < 0.001); suggesting a strong relationship between soil iron and soil arsenic concentrations. This finding indicates that arsenic-induced iron plaque formation on rice roots may be responsible for the observed stunted growth of rice plants. When compared with rice grains harvested from control sites, rice grains from the two Anum Valley paddy sites were found to contain significantly higher concentrations of arsenic. The health implications are briefly discussed.