Xie Shiyu, Su Yuanyuan, Qi Dan, Liu Fei, Gao Liu, Bao Ruiqi, Cheng Xing, Lin Xubing, Zhang Tingting, Peng Licheng
Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, Haikou 570228, PR China; School of Environmental Science and Engineering, Hainan University, Haikou 570228, PR China.
College of Ecology and Environment, Hainan Tropical Ocean University, Sanya 572000, PR China.
Water Res. 2025 May 15;276:123289. doi: 10.1016/j.watres.2025.123289. Epub 2025 Feb 13.
Previous studies on microplastics (MPs) distribution have predominantly focused on water bodies within specific regions, with limited emphasis on the contributions of MPs directly discharged from functional zones surrounding isolated island. This study addressed this gap by investigating the occurrence and distribution of MPs in water and sediment directly discharged into the adjacent coast of Hainan Island, a geographically isolated and ecologically sensitive region in the South China Sea. Based on the sampling from 40 typical sewage outlets (affiliated to five functional zones, i.e., wastewater treatment plants (WWTP), industrial area (ID), residential area (RA), aquaculture area (QA), estuary (EST)) around the Hainan Island, we analyzed the MPs abundance and composition in water and sediment. Our findings revealed significant contributions of land-derived MPs, with an average abundance of 15,900 items/m in water and 3171 items/kg in sediment. Annually, approximately 61.6 trillion MPs were discharged into the South China Sea via rivers from Hainan Island, highlighting its role as a major land-derived source of MPs pollution in this critical marine ecosystem. Risk assessments indicated the H and PLI level of Hainan Island as II and I, respectively, with H-water level highest in WWTP and EST as III and H-sediment level highest in WWTP, RD and QA as II, and this indicated the critical function of WWTP to control the release of land-derived MPs and reduce the environmental risks. Correlation analysis underscored the influence of natural factors (currents, tides, waves, and drifts), socio-economic factors (population density, regional area, and agricultural output), and anthropogenic activity (tourism development) on coastal MPs pollution. On the basis of existing timely MPs prevention and control measures in Hainan province, such as intercepting the MPs via WWTP and prohibiting the direct discharge of aquaculture wastewater to the surrounding sea, this study re-underscored the urgency of MPs management on the protection of the South China Sea's eco-environmental quality in view of the pivotal role of Hainan Island on the isolated geographic position and the South China Sea's ecological health. Overall, this study offered scientific insights to support source-oriented strategies for coastal MPs pollution control by providing fundamental data for predicting land-derived MPs contributions on an island-scale.
以往关于微塑料（MPs）分布的研究主要集中在特定区域的水体，对孤立岛屿周边功能区直接排放的微塑料贡献关注较少。本研究通过调查直接排入海南岛附近海岸（中国南海一个地理上孤立且生态敏感的地区）的水体和沉积物中微塑料的存在情况和分布，填补了这一空白。基于对海南岛周边40个典型污水排放口（隶属于五个功能区，即污水处理厂（WWTP）、工业区（ID）、居民区（RA）、养殖区（QA）、河口（EST））的采样，我们分析了水体和沉积物中微塑料的丰度和组成。我们的研究结果表明陆源微塑料贡献显著，水体中平均丰度为15900个/立方米，沉积物中为3171个/千克。每年，约61.6万亿个微塑料通过河流从海南岛排入南海，凸显了其作为这一关键海洋生态系统中陆源微塑料污染主要来源的作用。风险评估表明，海南岛的H值和PLI水平分别为II级和I级，其中污水处理厂和河口的H水等级最高，为III级，污水处理厂、居民区和养殖区的H沉积物等级最高，为II级，这表明污水处理厂在控制陆源微塑料排放和降低环境风险方面的关键作用。相关性分析强调了自然因素（水流、潮汐、波浪和漂流）、社会经济因素（人口密度、区域面积和农业产量）以及人为活动（旅游业发展）对沿海微塑料污染的影响。基于海南省现有的及时的微塑料防控措施，如通过污水处理厂拦截微塑料以及禁止向周边海域直接排放养殖废水，鉴于海南岛在地理位置孤立和南海生态健康方面的关键作用，本研究再次强调了微塑料管理对于保护南海生态环境质量的紧迫性。总体而言，本研究通过提供预测岛屿尺度陆源微塑料贡献的基础数据，为支持沿海微塑料污染控制的源头导向策略提供了科学见解。
