扎龙湿地沉积物微塑料赋存特征、来源及污染评价

Occurrence characteristics,sources and pollution assessment of microplastics in the sediments of Zhalong wetland

微塑料广泛分布在各种环境介质中,对生态环境及人体健康造成了一定程度的影响.为探究扎龙湿地沉积物中微塑料的污染程度及来源,本次采集78个沉积物样品,利用密度浮选、显微镜观察、傅里叶红外光谱测定、正定矩阵因子分解模型及污染负荷指数等方法,分析了扎龙湿地沉积物中微塑料的空间分布规律、赋存特征、来源、污染程度以及与沉积物理化性质之间的关系.结果表明,扎龙湿地沉积物微塑料丰度范围为28~7184 n·kg^(-1),平均值为(2418±1632) n·kg^(-1),主要分布在研究区的北部、东部及西南部.研究区沉积物中透明微塑料占比高(81.4%),碎片状是扎龙湿地微塑料的主要形态,粒径为14~50μm的微塑料含量占比高,为50.6%,聚合物类型主要成分是聚乙烯(PE).扎龙湿地微塑料主要来源于渔具及农业地膜.污染评价结果显示,扎龙湿地沉积物微塑料整体区域污染等级为Ⅱ级,属于中度污染,部分区域为严重污染.扎龙湿地沉积物中微塑料丰度与电导率、含水率、有机磷及无机磷之间均存在显著正相关关系(p<0.05),与铵态氮之间存在显著负相关关系(p<0.05).研究结果对扎龙湿地微塑料的污染防治、生态治理和保护丹顶鹤等野生动物具有重要参考价值.

Microplastics are widely distributed in various environmental media and pose a threat to the ecological environment and human health.To explore the pollution degree and source of microplastics,a total of 78 sediment samples were collected within the Zhalong wetland.Several methods including density separation,microscopic observation,Fourier transform infrared spectroscopy,positive matrix factorization models and pollution load indices were applied.The spatial distribution,occurrence characteristics,sources,pollution degree of microplastics,and the relationships between microplastics and physicochemical properties of the sediments in Zhalong wetland were analyzed.The results showed that the abundances of microplastics ranged from 28 n·kg^(-1) to 7184 n·kg^(-1),with an average of(2418±1632)n·kg^(-1),and the microplastics were mainly distributed in the northern,eastern and southwestern parts of the study area.Transparent microplastics accounted for a high proportion(81.4%)of the sediments in the study area and debris was the main form of microplastic in the Zhalong wetland.Microplastics with particle size of 14~50μm were dominant,accounting for 50.6%of total microplastics observed in the sediments of Zhalong wetland.The main component of microplastics was polyethylene(PE).The microplastics in the sediments were mainly sourced from fishing gear and agricultural mulch film.The pollution assessment results indicated that the microplastic pollution was level II,which belonged to moderate pollution in the whole study area,and some areas were seriously polluted.The abundance of microplastics in the sediments was positively correlated with conductivity,moisture content,organic phosphorus and inorganic phosphorus,and negatively correlated with ammonium nitrogen in the sediments.This study provided a valuable reference for the pollution prevention and control of microplastics,ecological management and protection of wild animals such as red-crowned cranes in the Zhalong wetland.