New insights into the vertical distribution and microbial degradation of microplastics in urban river sediments.
New insights into the vertical distribution and microbial degradation of microplastics in urban river sediments.
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DOI：
10.1016/j.watres.2020.116449
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发表时间：
2020-09
期刊：
影响因子：
12.8
通讯作者：
Lihua Niu;Yuanyuan Li;Yi Li;Qing Hu;Chao Wang;Jiaxin Hu;Wenlong Zhang;Longfei Wang;Chi Zhang-Chi
中科院分区：
文献类型：
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作者：
Lihua Niu;Yuanyuan Li;Yi Li;Qing Hu;Chao Wang;Jiaxin Hu;Wenlong Zhang;Longfei Wang;Chi Zhang-Chi
沉积物被发现是微塑料最重要的储存库之一，提供了丰富的原生微生物。微塑料的分布和降解行为所涉及的过程是复杂的。研究了城市河流沉积物中0 ~ 50 cm深度的微塑料（粒径< 5 mm）的垂直分布特征和微塑料上的细菌群落组合。结果表明，河流沉积物中塑料微粒及其微生物群落均呈现垂直分布特征。沉积物中微塑料的平均浓度由浅入深逐渐增加，且在较深的沉积物中以较小的微塑料颗粒为主。接触角测量，扫描电子显微镜和傅里叶变换红外光谱衰减全反射分析证实了更深层次的微塑料降解。与周围沉积物不同，微塑料上的细菌群落在细菌共现网络中呈现较高的正相关频率，表明微塑料上细菌群落的稳定性较差。指示性塑料降解菌在周围沉积物中的平均丰度为4.33%，在微塑料上的平均丰度为21.37%，从浅层到深层，指示性塑料降解菌在共生网络中的丰度和介数中心度均显著增加，这表明这些细菌在深层微塑料降解中的潜在主要作用。该研究为城市河流沉积物中微塑料的垂直分布和潜在的微生物降解特性提供了新的见解，扩展了我们对微塑料在水环境中归宿的理解。观察结果表明，微塑料在加深的沉积物中可能会变得更小，更多，最终迁移到地下水中，这是一个很大的风险。
Sediments have been found to be one of the most important reservoirs for microplastics, providing abundant indigenous microbes. The processes involved in the distribution and degradation behavior of microplastics are complex. This study investigated the vertical distribution of microplastics (with the size < 5 mm) and the bacterial community assemblages colonizing microplastics in urban river sediments at a depth from 0 to 50 cm. The results showed that both microplastics and associated microbial communities presented vertical profiles in river sediments. The mean concentration of microplastics increased from the shallow layers to the deep layers of sediments, and smaller microplastic particles were dominant in deeper layers. A greater degradation of microplastics in deeper layers was confirmed by contact angle measurements, scanning electron microscopy and Fourier transform infrared spectroscopy-attenuated total reflectance analyses. Unlike the surrounding sediments, the whole bacterial communities on microplastics exhibited higher frequency of positive correlations in the bacterial co-occurrence network, which indicated a less stability of bacterial communities on microplastics. The indicative plastic-degrading bacteria with an average abundance of 4.33% was found in the surrounding sediments, while on the microplastics 21.37% was found. From shallow layers to deep layers, the indicative plastic-degrading bacteria significantly increased both in the abundance and in their betweenness centrality in the co-occurrence network, which suggested a potentially primary role of these bacteria in the degradation of microplastics in deep layers. This study provides new insight into the vertical distribution and the potential microbial degrading characteristics of microplastics in urban river sediments, which expanded our understanding of the fate of microplastics in aquatic environments. The observed results implied a great risk that microplastics might become smaller and more in deepened sediments and finally migrate into groundwater.