Interaction between cadmium and atrazine during uptake by rice seedlings ( Oryza sativa L.)

Abstract

The uptake of atrazine by rice seedlings ( Oryza sativa L.) through plant roots from nutrient solution was investigated in the presence and absence of Cd 2+ over an exposure period of four weeks. It was found that both atrazine and Cd 2+ were toxic to rice seedlings. Both shoot and root biomasses decreased when the seedlings were exposed to increasing atrazine or Cd 2+ concentrations in nutrient solutions. In the absence of Cd 2+, a linear relationship was observed between atrazine concentrations in roots/shoots and in external solution, and more atrazine is concentrated in roots than in shoots. When atrazine and Cd 2+ concentrations in solution were maintained at mole ratio of 1:1, the accumulation of atrazine by seedlings was less and the seedling biomass was greater than found with other ratios, such as 1:2 or 2:1. Therefore, the formation of the complex between atrazine and Cd 2+ reduced the individual toxicities. Analyses of data with the quasi-equilibrium partition model indicated that the atrazine concentrations in rice seedlings and external water were close to equilibrium. In the presence of Cd 2+, however, the measured bioconcentration factor (BCF) of atrazine with roots and shoots were considerably greater. The latter findings resulted presumably from the atrazine–Cd 2+ complex formation that led to a large apparent BCF.