Norman Beth C, Xenopoulos Marguerite A, Braun Daniel, Frost Paul C
Department of Biology, Trent University, Peterborough, Ontario, Canada.
PLoS One. 2015 Jun 15;10(6):e0129328. doi: 10.1371/journal.pone.0129328. eCollection 2015.
Exposure to silver nanoparticles (AgNPs) may alter the structure and function of freshwater ecosystems. However, there remains a paucity of studies investigating the effects of AgNP exposure on freshwater communities in the natural environment where interactions with the ambient environment may modify AgNP toxicity. We used nutrient diffusing substrates to determine the interactive effects of AgNP exposure and phosphorus (P) enrichment on natural assemblages of periphyton in three Canadian Shield lakes. The lakes were all phosphorus poor and spanned a gradient of dissolved organic carbon availability. Ag slowly accumulated in the exposed periphyton, which decreased periphyton carbon and chlorophyll a content and increased periphyton C:P and N:P in the carbon rich lakes. We found significant interactions between AgNP and P treatments on periphyton carbon, autotroph standing crop and periphyton stoichiometry in the carbon poor lake such that P enhanced the negative effects of AgNPs on chlorophyll a and lessened the impact of AgNP exposure on periphyton stoichiometry. Our results contrast with those of other studies demonstrating that P addition decreases metal toxicity for phytoplankton, suggesting that benthic and pelagic primary producers may react differently to AgNP exposure and highlighting the importance of in situ assays when assessing potential effects of AgNPs in fresh waters.
接触银纳米颗粒（AgNP）可能会改变淡水生态系统的结构和功能。然而，对于在自然环境中AgNP暴露对淡水群落的影响，相关研究仍然匮乏，因为在自然环境中与周围环境的相互作用可能会改变AgNP的毒性。我们使用营养扩散基质来确定AgNP暴露和磷（P）富集对加拿大盾形区三个湖泊中周丛生物自然组合的交互作用。这些湖泊均贫磷，且溶解有机碳的可利用性存在梯度变化。银在暴露的周丛生物中缓慢积累，这降低了周丛生物的碳和叶绿素a含量，并增加了富碳湖泊中周丛生物的碳磷比和氮磷比。我们发现在贫碳湖泊中，AgNP和P处理对周丛生物碳、自养生物现存量和周丛生物化学计量存在显著的交互作用，即磷增强了AgNP对叶绿素a的负面影响，并减轻了AgNP暴露对周丛生物化学计量的影响。我们的结果与其他研究结果形成对比，其他研究表明添加磷会降低金属对浮游植物的毒性，这表明底栖和浮游初级生产者对AgNP暴露的反应可能不同，并突出了在评估AgNP对淡水的潜在影响时进行原位测定的重要性。
