Harmful effect of nanomaterials on aquatic organisms has accelerated in recent decades due to the growth emission of nanomaterials into water. In the present study, we analysed the toxic effects of TiO2, ZnO and MWCTN on diatoms Nitzschia palea in both individual and a combined way. After a short-term (96 h) exposure, the changes of cell density, chlorophyll a, MDA, SOD, CAT, total protein content and morphological structure were determined. Our results showed that: (1) The growth of N. palea was inhibited with the increase of concentration of nanomaterials; (2) The chlorophyll a content of N. palea was sensitive to these three individual nanomaterials; (3) Low concentration of nanomaterials promoted the MDA content in N. palea, but high concentration inhibited it; (4) The protein content of N. palea increased first and then decreased, indicating that nanomaterial stress inhibited diatom protein synthesis and showed dose-effect relationship; (5) After nanomaterial exposure, the SOD enzyme activity of N. palea was significantly inhibited, the CAT enzyme activity showed significantly decreased after exposure, comparing with control. The results of this study provide data for the study of algae nano-toxicology and provide a theoretical basis for the study of the toxicity of nanomaterials to freshwater microalgae.

Water eutrophication is widely associated with the explosion of phytoplankton productivity and the overdominance of some harmful phytoplankton species. Phytoplankton diversity indices are useful tools for describing trophic states. The relationship between phytoplankton diversity indices and trophic states is a relevant approach to assess water quality, but this approach has rarely been used to evaluate water quality in large quake lakes. To test the usefulness of phytoplankton diversity indices in water quality assessment, we investigated the taxonomy diversity-trophic state index (TSI) relationships for lakes in the second-largest quake lake worldwide, (Jingpo Lake, in China). Our results showed that Cyanophyta and Bacillariophyta were abundant at most stations during the study period. The Bacillariophyta assemblage was closely associated with organic pollution. The Margalef index and Shannon–Weaver index were relevant tools for evaluating trophic changes during the study period. The Pielou index had a weak ability to describe nutrient changes. Our findings highlight that phytoplankton taxonomy diversity indices are relevant tools in water quality assessment, but a selection of the fit index is necessary.

Phytoplankton taxonomic α-diversity indices are useful tools to characterize the trophic states in freshwater ecosystems. However, the application of these indices to assess trophic states in large barrier lakes is rare, especially in China. To test the usefulness of phytoplankton taxonomic α-diversity indices in trophic state assessments, we investigated the taxonomic α-diversity-Comprehensive Trophic Level Index (TLI) relationships in the second largest alpine lava barrier lake (Jingpo Lake, China) in the rainy and dry season from 2017 to 2018. Based on a two-year dataset, we found that there was a significant difference in the phytoplankton community, α-diversity indices, and TLI dynamic between the rainy season and the dry season. First, there was significant variation in phytoplankton abundance, the Margalef index, and the Shannon-Wiener index in different hydrological periods (p < 0.05). Second, the mean TLI in the rainy season (44 ± 5) was higher than in the dry season (41 ± 5) (p < 0.05). Lastly, the response characteristics of the Margalef and Shannon-Wiener index with TLI were different in different hydrological periods, and the relationship between the Pielou evenness index and TLI was weak. This study highlights that phytoplankton taxonomic α-diversity indices are relevant tools in water quality assessments but selecting the fit index is necessary. The current study provides key information about phytoplankton community, α-diversity, and trophic states in the largest alpine lava barrier lake, and the results of the study will benefit water quality management and biodiversity conservation in barrier lakes.

随着研究生招生规模的不断扩大,研究生教育已成为我国人才培养的重点之一.在研究生培养过程中尚存在诸多问题,其中如何提高研究生创新能力是人才培养的关键.本文就"依托科研项目培养研究生创新能力"立题,同时对如何建立促进研究生创新能力培养的良好环境及以科研项目为导向培养研究生的科研与创新能力等方面问题进行了有益的探索,并系统概述了提高研究生创新能力的主要措施,为研究生创新能力培养的探索与实践提供了参考价值和理论依据.

本研究于2015年在黑龙江省镜泊湖选取7个典型采样点,对镜泊湖春、夏两季间浮游生物群落结构的演替及其与环境因子关系进行分析.在调查期间共鉴定浮游植物152个分类单位,浮游动物38个分类单位,种类组成上浮游植物主要以绿藻门和硅藻门藻类为主,浮游动物以轮虫和原生动物为主.研究期间浮游生物优势种主要包括:河生集星藻(Actinastrum fluviatile (Schroed.) Fott)、梅尼小环藻(Cyclotella meneghiniana Kütz.)、谷皮菱形藻(Nitzschia palea (Kütz.) W.Smith)、前节晶囊轮虫(Asplanchna priodonta)、螺形龟甲轮虫(Keratella cochlearis)和瓶砂壳虫(Difflugia urceolata).在研究期间水温、pH、电导率、和总氮在春、夏两季之间变化明显(P＜0.05或P＜0.01).春、夏两季的浮游生物丰度呈现明显下降趋势(P＜0.05).Spearman相关分析揭示镜泊湖水体浮游生物丰度与水温和电导率极其显著相关(P＜0.01).冗余分析(RDA)表明,水温和电导率是驱动镜泊湖水体浮游生物群落生态分布的主要环境因子.与近10余年间镜泊湖相关研究对比发现,镜泊湖水体浮游植物群落结构较为稳定,浮游动物优势类群略有改变.综合营养状态指数评价表明镜泊湖水体为中营养状态,与前期研究结果相似,说明水体目前无进一步恶化的趋势.