Co-uptake of atrazine and mercury by rice seedlings from water

Abstract

The uptake of atrazine (ATR) by rice seedlings ( Oryza sativa L.) from nutrient solution was investigated in the presence and absence of Hg 2+ over a period of 96 h. Either ATR or Hg 2+ was found phytotoxic to rice seedlings, as they inhibited the seedling growth. The seedlings showed about 50% biomass reduction when exposed to 1.0 mg/L Hg 2+ alone in nutrient solution, and about 80% reduction when exposed to 12.0 mg/L ATR alone. Observed ATR and Hg 2+ levels (in mg/kg) in seedlings are not related to biomass changes. When either ATR or Hg 2+ was applied, the concentrations in seedlings increased largely in proportion to those in nutrient solution. The presence of Hg 2+ at 0.1 and 1.0 mg/L in solution caused a small-to-moderate decline in ATR uptake by the seedlings, the effect being largely independent of the ATR concentration in nutrient solution (at 6.0 and 12.0 mg/L). The presence of ATR (at 6.0 and 12.0 mg/L) in the nutrient solution led to small-to-moderate irregular changes in the Hg 2+ concentrations in rice seedlings. The overall results showed that there was no significant interdependence between the uptakes of ATR and Hg 2+ by rice seedlings, which is in contrast to the enhanced ATR uptake noticed earlier with Pb 2+ ion. Plant uptake of non-ionic organic compounds, such as ATR may be partly through water channels on the plasma membranes of plant cells.