杜氏盐藻对硫酸盐和镉的吸收及其相互关系

以对环境变化较为敏感的杜氏盐藻(Dunaliella tertiolecta)作为实验材料,研究了硫酸盐与镉的相互作用关系.结果表明,在两种 SO2-4水平(0.3mmnl·L-1,3mmol·L-1)条件下,相同浓度镉暴露时其总镉(TCd)含量基本相同,而 0.3mmol·L-1 SO2-4水平下,细胞内镉(ICd)的含量仅相当于3mmol·L-1 SO2-4 水平下的含量的40%左右,可能的机制是:在 SO2-4水平较高的情况下,细胞可以合成较高浓度的络合基团,从而使镉的生物可利用性和毒性大大增强;当镉暴露对杜氏盐藻的生长代谢产生抑制作用时,会诱导其对硫酸盐的吸收.因此,在进行水生生态系统的健康质量评价时,应当考虑S和Cd的相互作用.

Sulphate and cadmium interactions in Dunaliella tertiolecta

The interactions between sulphate and cadmium in Dunaliella tertiolecta were examined. Total Cd concentrations under both tested SO2-4 levels (0.3 mmol·L-1, 3 mmol·L-1) were comparable when exposed to the same Cd concentration; however, the intracellular Cd concentration under 0.3 mmol·L-1 SO2-4 was only 40% of its concentration under 3 mmol·L-1 SO2-4. One of the likely mechanisms is that cells that were growing in high SO2-4 medium may have synthesized high concentrations of protein ligands which enhanced the bioavailability and toxicity of Cd; and the inhibition of the growth and metabolism of D. tertiolecta resulting from Cd-exposure increased sulphate absorption by the algal cells. We suggest that the interactions between sulphate and cadmium should be considered when evaluating the quality of an aquatic ecosystem.