Ruangsomboon Suneerat, Wongrat Ladda
Faculty of Agricultural Technology, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand.
Aquat Toxicol. 2006 Jun 10;78(1):15-20. doi: 10.1016/j.aquatox.2006.01.015. Epub 2006 Feb 28.
The accumulation of cadmium (Cd) was studied in an experimental aquatic food chain involving the phytoplankton Chlorella vulgaris as the primary producer, the zooplankton Moina macrocopa as the primary consumer, and the catfish Clarias macrocephalus x Clarias gariepinus as the secondary consumer. C. vulgaris was first exposed to Cd solutions at 0.00, 0.35, and 3.50 mg l(-1), referred to as control group and experimental groups 1 and 2, respectively. Subsequently, each group was fed to three corresponding groups of M. macrocopa. Finally, three groups of catfish were fed these corresponding groups of M. macrocopa. After C. vulgaris was exposed to 3.50 mg l(-1) Cd (experimental group 2), the residual Cd in solution was only 4.01 microg l(-1), lower than the maximum allowable limit of Cd in natural water sources (5 microg l(-1)). Cd concentrations in C. vulgaris were 0.01+/-0.00 microg g(-1) (dry wt) in the control group, 194+/-1.80 microg g(-1) (dry wt) in experimental group 1, and 1140+/-20.06 microg g(-1) (dry wt) in experimental group 2. The Cd concentrations in M. macrocopa were 0.01+/-0.00 microg g(-1) (dry wt) in the control group, 16.48+/-2.23 microg g(-1) (dry wt) in experimental group 1, and 56.6+/-3.23 microg g(-1) (dry wt) in experimental group 2. The Cd concentrations in catfish muscle increased with increasing Cd concentrations in the food. After 60 days of fish culture, the mean concentrations of Cd in fish muscle were 0.01+/-0.00 microg g(-1) (dry wt) in the control group, 0.61+/-0.02 microg g(-1) (dry wt) in experimental group 1 and 1.04+/-0.06 microg g(-1) (dry wt) in experimental group 2. Cd concentration in fish muscle of experimental group 2 was equal to the permissible limit. Cd accumulation affected fish growth: at the end of the study, the mean fresh weight (12.81 g) of catfish in the control group, was significantly higher than those experimental group 1 (10.43 g) and experimental group 2 (10.00 g). The results showed that the measurement of Cd concentration in water does not necessarily give a measure of the safety of aquatic organisms as human food. Hence, heavy metal contamination is a matter for concern when organisms are harvested, for fish and human consumption, from natural water sources.
在一个实验性水生食物链中研究了镉（Cd）的积累情况，该食物链以普通小球藻作为初级生产者，大型溞作为初级消费者，以及杂交鲶（大口鲶×尖齿胡鲶）作为次级消费者。普通小球藻首先分别暴露于浓度为0.00、0.35和3.50 mg l⁻¹的镉溶液中，分别称为对照组以及实验组1和实验组2。随后，每组小球藻被投喂给三组相应的大型溞。最后，三组鲶鱼被投喂这些相应的大型溞。普通小球藻暴露于3.50 mg l⁻¹镉（实验组2）后，溶液中残留的镉仅为4.01 μg l⁻¹，低于天然水源中镉的最大允许限量（5 μg l⁻¹）。对照组普通小球藻中的镉浓度为0.01±0.00 μg g⁻¹（干重），实验组1为194±1.80 μg g⁻¹（干重），实验组2为1140±20.06 μg g⁻¹（干重）。大型溞中的镉浓度在对照组为0.01±0.00 μg g⁻¹（干重），实验组1为16.48±2.23 μg g⁻¹（干重），实验组2为56.6±3.23 μg g⁻¹（干重）。鲶鱼肌肉中的镉浓度随着食物中镉浓度的增加而增加。鱼类养殖60天后，对照组鱼肌肉中镉的平均浓度为0.01±0.00 μg g⁻¹（干重），实验组1为0.61±0.02 μg g⁻¹（干重），实验组2为1.04±0.06 μg g⁻¹（干重）。实验组2鱼肌肉中的镉浓度达到了允许限量。镉的积累影响了鱼类生长：在研究结束时，对照组鲶鱼的平均鲜重（12.81 g）显著高于实验组1（10.43 g）和实验组2（10.00 g）。结果表明，测量水中镉浓度不一定能衡量水生生物作为人类食物的安全性。因此，当从天然水源捕捞生物用于鱼类和人类消费时，重金属污染是一个值得关注的问题。
