南水北调中-东线水体颗粒物差异化特征及其对水质的影响OA

This study examines the spatiotemporal variations in the characteristics,sources,and water quality impacts of particulate matter in the Middle Route(enclosed artificial channel)and Eastern Route(open natural water system)of the South-to-North Water Diversion Project,driven by differences in water conveyance features.The research aims to clarify the composition and sources of particulate matter,and its influence on water quality in these two diversion systems,thereby providing a scientific basis for formulating differentiated water quality management strategies.During both dry and wet seasons,30 sampling points were established along the Middle and Eastern Routes to collect water samples and analyze water quality parameters and particulate matter characteristics.Correlation analysis was applied to compare the composition,distribution patterns,and relationships with nutrients of particulate matter between the two routes.Our key results showed that:1)The Middle Route exhibited stable and good water quality,with suspended particulate matter(SPM)dominated by coarse particles(>63 μm,accounting for 61.43～94.68%).Total phosphorus(TP)was below 0.01 mg∙L-1 and was negatively correlated with coarse particles.Chlorophyll-a was significantly positively correlated with coarse particles(r=0.60),indicating that algal aggregation dominated particulate matter formation.2)The Eastern Route showed high and fluctuating nitrogen and phosphorus concentrations,with SPM dominated by fine particles(<20 μm,accounting for 51.26～88.61%).TP ranged from 0.03 to 1.11 mg∙L-1and was positively correlated with fine particles,highlighting significant external input.3)Carbon and nitrogen isotope tracing revealed that particulate matter in the Middle Route originated primarily from endogenous algae(contribution>46.75%),whereas the Eastern Route was influenced by both terrestrial plants and algae.Due to differences in engineering settings and management approaches,the characteristics and sources of particulate matter differ significantly between the two routes,consequently shaping distinct water quality dynamics.In the Middle Route,algal aggregation facilitates nutrient absorption and water quality stability but may increase the risk of algal-derived particulate deposition.In contrast,the Eastern Route is significantly influenced by external inputs and the adsorption-desorption processes of fine particles.It is recommended that the Middle Route adopt an"algae reduction-optimized hydrodynamic regulation"strategy to suppress the deposition of algal-derived coarse particles,while the Eastern Route implement a"retention and sedimentation-wetland purification"strategy to reduce external fine particles and pollutant inputs.This study provides theoretical support and practical guidance for the differentiated regulation of particulate matter in long-distance water diversion systems.