Heavy Metal Levels in Paddy Soils and Rice (<i>Oryza sativa</i> (L)) from Wetlands of Lake Victoria Basin, Tanzania

Abstract

A survey of paddy fields in Lake Victoria Basin (LVB) wetlands was conducted at a wider scale in different locations including closer to mining and within urbanized areas in Tanzania. The objective of the study was mainly to assess the present situation with regard to levels of heavy metals in O. sativa grains harvested locally as well as to set the baseline levels of some heavy metals in paddy fields. The results showed that the levels of Cadmium, Chromium, Copper, Lead, Zinc and total Mercury in brown rice are generally within the acceptable levels for human food. However, higher concentration of Hg was found in the husks, suggesting the significance of atmospheric dispersal of Hg in the basin. It is also worthwhile noting that all the sampled paddy fields in LVB have heavy metal concentrations within limits for production of safe rice for human consumption.

Keywords: Wetlands; Lake Victoria Basin; Heavy metals; Paddy soil; Rice

Tanz. J. Sci. Vol 36 2010, 59-72