Hydrological forcing reshapes nitrogen partitioning under microplastic amendment in hyporheic zones

IF 7.3 1区地球科学 Q1 ENGINEERING, CIVIL

Journal of Hydrology Pub Date : 2026-10-28 DOI:10.1016/j.jhydrol.2026.136686

Shiqi Liu, Zhenhua Yan, Tao Zhang, Xi Chen, Lan Ma, Yuqiong Yang, Ping Lu, Saiyu Yuan, Guanghua Lu

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引用次数: 0

Abstract

Microplastics (MPs) are increasingly recognized as potential modifiers of nitrogen (N) cycling in aquatic sediments. Hyporheic zones (HZs), hotspots for riverine N transformation and important sinks for MPs, are exposed to dynamic hydrological forcing. However, how hydrological forcing structures N transformation responses in MP-amended HZs remains poorly understood. Here, we used field-collected sediments to simulate HZs and examined N transformation responses in sediments amended with conventional polyvinyl chloride (PVC) and biodegradable polylactic acid (PLA) MPs under contrasting drying-rewetting alternation (DWA) regimes and hydraulic retention time (HRT) levels. DWA enhanced sediment reoxygenation, weakened dissolved oxygen (DO) stratification, and altered putative nitrification-related taxa, enzyme-associated protein responses, and selected N-cycling functional genes in a polymer-specific manner. In PVC-amended HZs, DWA strengthened the coupling between nitrification-related responses and apparent nitrate reduction, whereas in PLA-amended HZs it promoted oxidative N transformation indicators but reduced apparent nitrate reduction, NO2− accumulation, and NH4+ accumulation. Longer HRT reduced DO availability and generally increased apparent NO3− reduction. In PVC-amended HZs, this was accompanied by greater NO2− and NH4+ accumulation. In PLA-amended HZs, higher dissolved organic carbon (DOC) availability and sustained low-DO conditions coincided with greater apparent NO3− reduction and stronger NO2− and NH4+ accumulation. Multivariate analyses identified DO-centered associations under DWA and PVC-HRT, whereas DOC-centered associations emerged under PLA-HRT. These findings show that hydrological regime and polymer identity jointly structure N transformation responses in MP-amended HZs, with distinct patterns associated with oxygen availability, carbon availability, and nitrate-derived N partitioning.

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水文强迫重塑了低渗带微塑性修正下的氮分配

微塑料（MPs）越来越被认为是水生沉积物中氮(N)循环的潜在改性剂。潜流带（HZs）是河流氮转化的热点和MPs的重要汇，暴露于动态水文强迫之下。然而，水文强迫如何在mp修正的HZs中结构N转化响应仍然知之甚少。在这里，我们使用现场收集的沉积物来模拟hz，并在不同的干燥-再湿交替（DWA）制度和水力保留时间（HRT）水平下，研究了用常规聚氯乙烯（PVC）和可生物降解聚乳酸（PLA） MPs修正的沉积物中的N转化响应。DWA以聚合物特异性的方式增强了沉积物的再氧化，减弱了溶解氧（DO）分层，改变了假定的硝化相关分类群，酶相关蛋白反应，并选择了n循环功能基因。在pvc改性的HZs中，DWA增强了硝化相关反应和硝酸盐表观还原之间的耦合，而在pla改性的HZs中，DWA促进了氧化N转化指标，但降低了硝酸盐表观还原、NO2−积累和NH4+积累。较长的HRT降低了DO的可用性，并且通常增加了NO3−的明显减少。在pvc改性的hz中，这伴随着更大的NO2−和NH4+积累。在pla修饰的HZs中，较高的溶解有机碳（DOC）有效性和持续的低do条件与更大的NO3 -还原和更强的NO2 -和NH4+积累相一致。多变量分析发现，DWA和PVC-HRT组存在以do为中心的关联，而PLA-HRT组存在以doc为中心的关联。这些发现表明，水文环境和聚合物特性共同决定了mp修饰的HZs中N转化的响应，并与氧有效性、碳有效性和硝酸盐衍生的N分配有不同的关联模式。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Hydrology 地学-地球科学综合

CiteScore

11.00

自引率

12.50%

发文量

1309

审稿时长

7.5 months

期刊介绍： The Journal of Hydrology publishes original research papers and comprehensive reviews in all the subfields of the hydrological sciences including water based management and policy issues that impact on economics and society. These comprise, but are not limited to the physical, chemical, biogeochemical, stochastic and systems aspects of surface and groundwater hydrology, hydrometeorology and hydrogeology. Relevant topics incorporating the insights and methodologies of disciplines such as climatology, water resource systems, hydraulics, agrohydrology, geomorphology, soil science, instrumentation and remote sensing, civil and environmental engineering are included. Social science perspectives on hydrological problems such as resource and ecological economics, environmental sociology, psychology and behavioural science, management and policy analysis are also invited. Multi-and interdisciplinary analyses of hydrological problems are within scope. The science published in the Journal of Hydrology is relevant to catchment scales rather than exclusively to a local scale or site.