Harmful effect of nanoparticles on the functions of freshwater ecosystems: Insight into nanoZnO-polluted stream

ZnO nanoparticle toxicity on aquatic organisms has been extensively studied, but its concentration-and time-dependent effects on ecosystem functioning are remain uncertain. Here we assessed the harmful effects of nano-ZnO (10, 100, 1000 mg L-1) on the stream functioning by using a microcosm system simulating poplar leaf decomposition for 50 days. The 100 mg L-1 ZnO nanoparticles had significantly and stably inhibitory effect on the litter decomposition during the exposure period. The inhibition was not detected in the 10 mg L-1 treatment until 43 d. In contrast, the significant and continuous inhibition started to disappear from 43 d in the 1000 mg L-1 treatment. The varied consequences on litter decomposition might be directly affected by the different ZnO nanoparticle homogeneity of the different treatments. ZnO nanoparticles led to significant decreases in pH value of the decomposition environment, which had significant and positive relationships to the activities of dehydrogenase, glycine-aminopeptidase, N-acetylglucosaminidase, and acid phosphatase. Besides, 10 and 1000 mg L-1 ZnO nanoparticles led to lower fungal diversity, which was negatively related to the variability of decomposition. In conclusion, fungal decomposers showed different responses to the different concentrations of ZnO nanoparticle, and ultimately affected the stability of ecosystem functions. Published by Elsevier Ltd.

氧化锌纳米粒子对水生生物的毒性已被广泛研究，但其对生态系统功能的浓度和时间依赖性影响仍不确定。在此，我们通过使用一个模拟杨树叶分解50天的微宇宙系统，评估了纳米氧化锌（10、100、1000毫克/升）对溪流功能的有害影响。在暴露期间，100毫克/升的氧化锌纳米粒子对凋落物分解有显著且稳定的抑制作用。在10毫克/升的处理组中，直到第43天才检测到抑制作用。相反，在1000毫克/升的处理组中，从第43天开始显著且持续的抑制作用开始消失。对凋落物分解的不同结果可能直接受到不同处理组中氧化锌纳米粒子均匀性差异的影响。氧化锌纳米粒子导致分解环境的pH值显著下降，这与脱氢酶、甘氨酸 - 氨基肽酶、N - 乙酰氨基葡萄糖苷酶和酸性磷酸酶的活性呈显著正相关。此外，10毫克/升和1000毫克/升的氧化锌纳米粒子导致真菌多样性降低，这与分解的变异性呈负相关。总之，真菌分解者对不同浓度的氧化锌纳米粒子表现出不同的反应，并最终影响生态系统功能的稳定性。由爱思唯尔有限公司出版。