摘要

越来越多的证据表明，微米和纳米塑料颗粒会对水生生物产生不利影响。到目前为止，暴露研究主要是定性的，因为颗粒摄取的定量测量在分析上具有挑战性。因此，本研究的目的是使用定量方法确定大型蚤中微量和纳米塑料的摄取和消化，并分析粒径，暴露持续时间和食物存在的影响。将一周大的动物暴露于2μm和100nm荧光聚苯乙烯珠（1mg / l）24小时，然后在干净的培养基中24小时的消化期。在两个阶段期间，通过测量溶解组织中的荧光强度来确定颗粒的体重。在不存在和存在食物的情况下研究摄取和消化（每毫升6.7×105细胞的Raphidocelis subcapitata）。此外，测量了水蚤在颗粒暴露下的摄食率，以及在暴露21天（1mg / l，0.5mg / l和0.1mg / l）期间对繁殖的影响，以研究潜在的生理损伤。两种粒径都很容易摄入，但2μm粒子的摄取质量数量比100nm粒子高5倍。 24小时内未发生完全消化，但通常消耗较高量的2μm颗粒。在食物存在下，颗粒的动物体负荷大大减少。在存在100nm颗粒的情况下，Daphnid进料速率降低了21％，但是在21天暴露结束时尽管颗粒的身体负担很高，但没有发现对繁殖的影响。由100nm颗粒引起的较低的消化和降低的进料速率可能表明，与较大的颗粒尺寸相比，纳米尺寸范围的颗粒对D. magna可能更具危险性。

Evidence is increasing that micro- and nanoplastic particles can have adverse effects on aquatic organisms. Exposure studies have so far mainly been qualitative since quantitative measurements of particle ingestion are analytically challenging. The aim of this study was therefore to use a quantitative approach for determining ingestion and egestion of micro- and nanoplastics in Daphnia magna and to analyze the influence of particle size, exposure duration and the presence of food. One week old animals were exposed to 2 μm and 100 nm fluorescent polystyrene beads (1 mg/l) for 24 h, followed by a 24 h egestion period in clean medium. During both phases body burdens of particles were determined by measuring the fluorescence intensity in dissolved tissues. Ingestion and egestion were investigated in the absence and presence of food (6.7·105 cells of Raphidocelis subcapitata per ml). Furthermore, feeding rates of daphnids in response to particle exposure were measured as well as effects on reproduction during a 21 days exposure (at 1 mg/l, 0.5 mg/l and 0.1 mg/l) to investigate potential impairments of physiology. Both particle sizes were readily ingested, but the ingested mass of particles was five times higher for the 2 μm particles than for the 100 nm particles. Complete egestion did not occur within 24 h but generally higher amounts of the 2 μm particles were egested. Animal body burdens of particles were strongly reduced in the presence of food. Daphnid feeding rates decreased by 21% in the presence of 100 nm particles, but no effect on reproduction was found despite high body burdens of particles at the end of 21 days exposure. The lower egestion and decreased feeding rates, caused by the 100 nm particles, could indicate that particles in the nanometer size range are potentially more hazardous to D. magna compared to larger particle sizes.

https://www.ncbi.nlm.nih.gov/pubmed/28554029