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Updated: Jan 27, 2026

Protocol for Microplastics Sampling on the Sea Surface and Sample Analysis
Published on: December 16, 2016
Effects of microplastics on inorganic nitrogen dynamics in surface water sediments under different disturbance
Mengmeng Li1, Liang Chen1, Qizhong Guo2
1State Key Laboratory of Hydraulic Engineering Intelligent Construction and Operation, Tianjin University, Tianjin 300350, PR China; School of Civil Engineering, Tianjin University, Tianjin 300350, PR China.
Abstract:
Microplastics (MPs) increasingly accumulate in sediments, and frequent anthropogenic disturbances (e.g., dredging) in freshwater systems make it essential to investigate their influence on inorganic nitrogen dynamics under disturbed conditions. Disturbance simulation experiments were conducted to investigate how MPs affect nitrogen migration and transformation in aquatic environments. At low MP concentrations (1 %), MPs enhanced ammonium (NH4+) desorption at the surface by 92 %. In contrast, higher concentrations (5 %) impeded sediment upward migration and reduced NH4+ desorption by 64 %. MPs also showed a dose-dependent effect on NO3 consumption, with 5 % MPs increasing it by 104 % at the surface and by 21 % at the sediment-water interface. The consumed NO3 is largely converted to NH4+ via dissimilatory NO3 reduction to NH4+ (DNRA), with MPs influencing this process by altering sediment resuspension and redox conditions. NH4+ variation across MP treatments diminished as disturbance intensity (DI) increased. Three-factor analysis of variance (ANOVA) confirmed that DI was the dominant driver of NH4+ variation (p = 0.010) rather than MPs.
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