Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, NC 27695, USA.
Environ Pollut. 2010 Jan;158(1):272-7. doi: 10.1016/j.envpol.2009.07.010. Epub 2009 Jul 31.
In streams, periphyton biofilms are important sinks for trace metals such as cadmium and are primary food sources of many invertebrate consumers. To study Cd trophic transfer, we produced differentially contaminated diets by exposing natural periphyton to environmentally relevant dissolved Cd ranging from 0 to 10 microg L(-1) for 6-7 days using a radiotracer approach. On average, periphyton grown during three different seasons bioconcentrated Cd similarly--approximately 1315 (+/-442) -fold above dissolved concentrations. However, mayfly larvae (Centroptilum triangulifer) raised on these differentially contaminated diets (first instar through adulthood) had significantly higher trophic transfer factors from periphyton grown in Aug and Nov 2008 (4.30 +/- 1.55) than from periphyton grown in Jan 2009 (0.85 +/- 0.21). This Cd bioaccumulation difference is only partially explained by apparent food quality and subsequent growth differences. Taken together, these results suggest that primary producers at the base of food webs drive metal bioaccumulation by invertebrate grazers.
在溪流中，周丛生物膜是痕量金属（如镉）的重要汇，也是许多无脊椎动物消费者的主要食物来源。为了研究镉的营养转移，我们采用放射性示踪剂的方法，将天然周丛生物暴露于环境相关的溶解态镉中，范围为 0 至 10 微克/升，持续 6-7 天，从而生产出具有不同程度污染的饮食。平均而言，在三个不同季节生长的周丛生物对镉的生物浓缩相似——大约比溶解浓度高 1315（+/-442）倍。然而，在这些具有不同污染程度的饮食（从第一龄幼虫到成虫）中饲养的蜉蝣幼虫（Centroptilum triangulifer），从 2008 年 8 月和 11 月生长的周丛生物（4.30+/-1.55）转移到镉的营养转移系数明显高于从 2009 年 1 月生长的周丛生物（0.85+/-0.21）。这种镉生物积累的差异仅部分可以用表观食物质量和随后的生长差异来解释。总之，这些结果表明，食物网底部的初级生产者通过无脊椎动物捕食者驱动金属的生物积累。
