Microplastics have become a research hotspot in the environmental field owing to their persistence and complex ecological effects. Although microplastics have attracted public attention only recently, the microplastic pollution in lake, a unique water system characterized by their irreplaceable ecological value and special hydrodynamic conditions, were increasingly documented, calling for a summary of the most recent advance in this research area. Therefore, the sampling and analysis methods, occurrence, sources, and ecological effects of microplastics in lakes were summarized in this review. Various types of plastics are produced and used in large quantities for different purposes, resulting in microplastic pollution being widespread in lakes worldwide, albeit with different levels and characteristics. Microplastics constantly migrate and transform in lake ecosystems, exerting impacts on ecological, including pollution diffusion and biological toxicity. This review focused on the migration of microplastics in water and food chains, which is a different perspective than that considered in previously published reviews. This review also discussed the limitations of existing studies and made recommendations. Future research directions should include the following: 1) improving the baseline database of microplastic pollution in lakes; (2) unifying the sampling and laboratory analysis methods; (3) exploring the quantitative analysis methods of the sources, transportation, and fate of microplastics; (4) considering more factors to explore the effects of microplastics on lake ecosystems.

Coral reefs are ecosystems that are highly vulnerable to external environmental impacts, including changes associated with ocean acidification and global warming. Assessing the vulnerability of coral reef growth environments over large areas of the sea is a difficult and complex process, as it is influenced by many variables. There are few studies on environmental vulnerability assessment of coral islands and reefs in the South China Sea. It is therefore particularly important to understand the environmental sensitivity of corals and how coral communities respond to changes in climate-related environmental variables. In this study, indicators were selected mainly from natural environmental factors that hinder the development of coral reefs. The sea surface temperature (SST), sea surface salinity (SSS), wind velocity (WV) and direction, sea level height (SL), ocean currents (OC), and chlorophyll concentration (Chl) of coral reefs in South China Sea Island were integrated to calculate the coral reef environmental vulnerability region. In a GIS environment, Spatial Principal Component Analysis (SPCA) was used to develop sensitivity models and evaluate the ecological vulnerability of coral reefs. Based on the Environmental vulnerability indicator (EVI) values, the study area was classified as 5 grades of ecological vulnerability: Potential (0.000–0.577), Light (0.577–0.780), Medium (0.780–0.886), Heavy (0.886–0.993) and Very Heavy (0.993–1.131). Sensitivity models identified regional gradients of environmental stress and found that some coral reefs in western Malaysia and southwestern Philippines have higher vulnerability. Meanwhile, the study found that the reefs of Paracel Islands and Macclesfield Bank areas of medium vulnerability. Future use of high-precision data from long time series will allow better estimates of site-specific vulnerability and allow for the precise establishment of marine protected areas so that the ecological diversity of coral reefs can be sustained.

With the rapid development of cities and the impact of climate change, cities located near rivers are facing an increasingly serious flood threat. Urban flood risk prediction management is pressing. The peak discharge and duration are important factors in urban flood management as well as the important characteristics of flood hygrograph. Mostly, hydrological model is used to obtain the upstream flood hygrograph to drive inundation model. However, lack of information on reservoirs, barrage structures and land use make it difficult to construct high-precision hydrological models, especially in upstream cities where data is lacking. In this study, therefore, we propose an approach to urban flood management based on measured flood data from urban hydrological stations in close proximity to derive flood hydrography for different return periods, and establish a high-precision urban-scale river flood risk management method by combining with Unmanned Aerial Vehicle (UAV) survey data. This method can allow information on river construction and underlying surface change to be introduced into the flood hygrograph implicitly, thus avoiding the difficulty of establishing hydrological and hydrodynamic coupling of the whole basin. The applicability and accuracy of the methodology are explored in this article with reference to Chenxi City in the upper reaches of Yuanshui River. Comparison the flood process of the 10-year with the actual flood in 2016 indicates that the extent of inundation is strongly dependent on the instantaneous discharge, with the peak flow largely determining the maximum inundation extent and risk level. This illustrates the feasibility of risk assessment of urban flooding based on flood hygrograph with different period levels derived from measured flood processes at adjacent sites. Subsequently, the different return periods scenario is simulated and analyzed. This approach provides technical guidance for flood risk assessment in areas where data is lacking (e.g., upstream mountainous cities).

南沙岛礁的发育受空间位置、暴露面积及地质结构等因素的影响,礁体的演变伴随空间形态的变化.本文利用遥感和地理信息系统(GIS)相结合的方法绘制南沙岛礁核密度现状图,并采用Kernel Density进一步分析南沙礁群空间核密度分布.研究表明:南沙岛礁空间形态复杂,有明显区域格局性,面积差异较大的岛礁核密度聚集位置不相同,分布特征相对密集.岛礁数量在纬度方向有明显浮动,在经度方向上趋于稳定.随礁体面积的增大,礁体平均形状指数逐渐增大,平均紧凑度逐渐减小,形状指数LS1介于0.90～ 2.87之间、紧凑度RC介于0.31～ 0.97之间.研究结果有助于更好地了解南沙岛礁密度情况,为海洋管理人员提供参考信息.