Töpperwien Stefanie, Xue Hanbin, Behra Renata, Sigg Laura
Eawag, Swiss Federal Institute of Aquatic Science and Technology, P.O. Box 611, CH-8600 Dübendorf, Switzerland.
Environ Sci Technol. 2007 Aug 1;41(15):5383-8. doi: 10.1021/es070657l.
Cd accumulation in cultures of Scenedesmus vacuolatus, a freshwater alga, was investigated in water samples from freshwater systems (two hard- and one softwater system) and compared to accumulation from synthetic culture medium. The Cd accumulation in S. vacuolatus was compared to total, labile, and free Cd measured by various analytical methods. In the hardwater samples, Cd accumulation was similar to accumulation from the culture medium and approximately followed the free ion activity model. In the softwater system, Cd accumulation increased with increasing free and total Cd concentrations, but was lower than expected from the free Cd2+ concentrations compared to the other freshwaters and culture media. Cd accumulation in the various freshwaters was not simply related to labile and free Cd concentrations measured by several methods. From experiments using fulvic acid as a ligand in the culture medium, no influence on Cd accumulation other than by modifying the Cd speciation was detected. Modeling of the Cd uptake revealed that besides cation and proton competition, other factors such as dissolved organic carbon composition and the presence of colloids might reduce Cd accumulation in softwater systems.
研究了淡水藻类空星藻（Scenedesmus vacuolatus）在淡水系统（两个硬水系统和一个软水系统）水样中的镉积累情况，并与合成培养基中的镉积累进行了比较。将空星藻中的镉积累与通过各种分析方法测得的总镉、活性镉和游离镉进行了比较。在硬水样品中，镉积累与培养基中的积累相似，大致遵循游离离子活性模型。在软水系统中，镉积累随着游离镉和总镉浓度的增加而增加，但与其他淡水和培养基相比，低于根据游离镉离子浓度预期的积累量。各种淡水中的镉积累与通过几种方法测得的活性镉和游离镉浓度并非简单相关。在培养基中使用富里酸作为配体的实验表明，除了改变镉的形态外，未检测到对镉积累的其他影响。镉吸收的模型表明，除了阳离子和质子竞争外，其他因素如溶解有机碳组成和胶体的存在可能会降低软水系统中的镉积累。
