Evaluation of mercury pollution in cultivated and wild plants from two small communities of the Tapajós gold mining reserve, Pará State, Brazil

This study examines the total Hg contamination in soil and sediments, and the correlation between the total Hg concentration in soil and vegetables in two small scale gold mining areas, São Chico and Creporizinho, in the State of Para, Brazilian Amazon. Total Hg values for soil samples for both study areas are higher than region background values (ca. 0.15 mg/kg). At São Chico, mean values in soils samples are higher than at Creporizinho, but without significant differences at α < 0.05 level. São Chico's aboveground produce samples possess significantly higher values for total Hg levels than samples from Creporizinho. Creporizinho's soil–root produce regression model were significant, and the slope negative. Creporizinho's soil-aboveground and root wild plants regression models were also significant, and the slopes positives. Although, aboveground : root ratios were > 1 in all of São Chico's produce samples, soil–plant parts regression were not significant, and Hg uptake probably occurs through stomata by atmospheric mercury deposition. Wild plants aboveground : root ratios were < 1 at both study areas, and soil–plant parts regressions were significant in samples of Creporizinho, suggesting that they function as an excluder. The average total contents of Hg in edible parts of produces were close to FAO/WHO/JECFA PTWI values in São Chico area, and much lower in Creporizinho. However, Hg inorganic small gastrointestinal absorption reduces its adverse health effects.