黄河口潮间带沉积物中微塑料的赋存特征、来源及生态风险

Occurrence Characteristics, Sources and Ecological Risk of Microplastics in Intertidal Sediments of the Yellow River Estuary

摘要:

微塑料(microplastics,MPs)作为一种新污染物,已成为全球环境领域的研究热点。黄河口是我国重要的河口湿地和生态保护区,研究其潮间带MPs污染特征,不仅有助于理解陆源MPs的入海过程,还可为河口MPs生态风险评估提供科学依据。本研究通过在黄河三角洲内外潮间带区域采集表层沉积物样品，系统分析其中MPs（53-5000 μm）的分布规律、形态特征及来源，并评估其生态风险。结果表明,MPs丰度存在空间差异：三角洲内呈现东高西低趋势(范围60–520 item/kg；均值257.5±166.58 item/kg),而三角洲外则相反(范围160–880 item/kg；均值360±249.8 item//kg),这种丰度分布模式主要由渤海南部逆时针洋流影响下的黄河冲淡水扩散模式决定。形态分析显示,纤维状MPs占比最高(三角洲外54.7%,三角洲内35.8%),其次为颗粒状(三角洲外17.2%,三角洲内25.9%),且小粒径(<1 mm)MPs占主导(三角洲外57.5%,三角洲内74%)。聚合物组成呈现区域差异：三角洲外以纤维素(43.7%)和聚对苯二甲酸乙二醇酯(18.8%)为主,主要来自生活污水；而三角洲内纤维素(23.5%)、聚对苯二甲酸乙二醇酯(23.5%)和聚氯乙烯(23.5%)共存,表明以工业源次生MPs通过黄河输入为主。污染负荷指数(pollution load index,PLI)评估显示,研究区域整体处于轻度污染水平(PLI<1),但三角洲内(PLI=0.765)污染程度高于三角洲外(PLI=0.629),其中B5和B6-2站位达到中度污染。研究结果对黄河三角洲生态保护具有重要指导意义。

Abstract:

Microplastics (MPs), as emerging contaminants, have become a prominent research focus within global environmental science. The Yellow River Estuary, a nationally significant estuarine wetland and ecological conservation zone in China, represents a critical area for investigating MP pollution in intertidal environments. Studying the contamination characteristics of MPs in this region not only advances understanding of terrestrial MP transport processes to the marine environment but also provides a scientific basis for ecological risk assessments of MPs in estuarine systems. This study systematically analysed the distribution patterns, morphological characteristics, and sources of MPs (53–5000 μm) within surface sediment samples collected from intertidal zones both within and outside the Yellow River Delta, whilst also assessing their ecological risks. Results demonstrate distinct spatial variations in MP abundance: the inner delta exhibited a decreasing gradient from east to west (range: 60–520 items/kg; mean: 257.5 ± 166.58 items/kg), while the outer delta displayed an inverse pattern (range: 160–880 items/kg; mean: 360 ± 249.8 items/kg). This distribution pattern is primarily governed by the dispersion of Yellow River freshwater plumes under the influence of the counterclockwise circulation in the southern Bohai Sea. Morphological analysis revealed fibrous MPs as the predominant type (54.7% in outer delta; 35.8% in inner delta), followed by granular fragments (17.2% in outer delta; 25.9% in inner delta), with small-sized MPs (<1 mm) dominating both regions (57.5% in outer delta; 74% in inner delta). Polymer composition showed regional differentiation: the outer delta was dominated by cellulose (43.7%) and polyethylene terephthalate (18.8%), primarily derived from domestic wastewater, while the inner delta exhibited comparable proportions of cellulose (23.5%), polyethylene terephthalate (23.5%), and polyvinyl chloride (23.5%), indicating predominant input of industrial-source secondary MPs via fluvial transport. Pollution Load Index (PLI) assessment indicated overall mild contamination levels (PLI<1) across the study area, with higher contamination in the inner delta (PLI=0.765) compared to the outer delta (PLI=0.629). Specific stations B5 and B6-2 reached moderate pollution levels. These findings provide significant implications for ecological conservation strategies in the Yellow River Delta.