【摘要】 为认识大汶河典型干流段不同水平年DO和NH₃-N的时空分布特征，研究基于EFDC模型构建了典型河段水动力水质模型，量化揭示了DO与NH₃-N浓度的时空分布规律，并识别了关键污染时段与河段。结果表明：在平水年份，DO浓度于8月降至全年最低值5 mg/L,NH₃-N则达到全年峰值0.3 mg/L；在枯水年份，NH₃-N浓度在3月达峰值0.843 mg/L，随4月降水量增加至42.2 mm后显著下降，DO浓度则维持在7.0-8.6 mg/L的稳定区间；在丰水年份，径流量相较于降水量存在约1个月的滞后响应，8月达降水峰值228 mm后，9月DO降至最低值6.3 mg/L,NH₃-N增至最高值0.318 mg/L，二者变化呈负相关。空间分布上，平水年份与枯水年份非汛期DO浓度由大汶口至河口整体呈递增趋势，增量约1.2-1.8 mg/L，丰水年份则在戴村坝区域聚集，中部较上下游高0.5-0.9 mg/L；平水年份汛期形成“大汶口>河口>中部”的结构，枯水年份戴村坝区域浓度较上下游高0.4-0.7 mg/L。NH₃-N浓度空间分布整体呈递减模式，大汶口至河口浓度降幅达48%-67%，仅丰水年份汛期在中游富集，较上下游高0.3-0.5 mg/L。受自然因素和人类活动的共同影响，河段水质在时空上均表现出不均匀性，研究结果为制定科学有效的水污染防治对策和水资源管理策略提供模型基础和科学依据。更多还原

【Abstract】 To understand the spatiotemporal distribution characteristics of DO and NH₃-N in the typical mainstream section of the Dawen River under different level years, this study constructs a hydrodynamic water quality model for the typical river section based on the EFDC model. It quantitatively reveals the spatiotemporal distribution patterns of DO and NH₃-N concentrations, and identifies the key pollution periods and river sections. The results show that in a normal year, DO concentration drops to its annual minimum of 5 mg/L in August, while NH₃-N reaches its peak of 0.3 mg/L. In a dry year, NH₃-N concentration reaches a peak of 0.843 mg/L in March, and decreases significantly with precipitation increased to 42.2 mm in April, while DO concentration remains stable within 7.0-8.6 mg/L. In a wet year, runoff lags behind precipitation by about one month; after precipitation peaks at 228 mm in August, DO drops to its lowest value of 6.3 mg/L in September, while NH₃-N increases to its highest value of 0.318 mg/L, showing a negative correlation between the two. Spatially, during the non-flood season, in normal and dry years, DO concentration generally increases from Dawenkou to the estuary, with an increase of about 1.2-1.8 mg/L, while in wet increases from Dawenkou to the estuary, with an increase of about 1.2-1.8 mg/L, while in increases increases from Dawenkou to the estuary, with an increase of about 1.2-1.8 mg/L, while in wet years, DO is concentrated in the Daicun Dam area, with the midstream section being 0.5-0.9 mg/L higher than upstream and downstream sections. During the flood season, in normal years, DO shows a pattern of “Dawenkou > estuary > midstream”, while in dry years, concentrations in the Daicun Dam area are 0.4-0.7 mg/L higher than in upstream and downstream sections. NH₃-N concentration generally exhibits a decreasing spatial pattern, with reductions of 48%-67% from Dawenkou to the estuary, except during the flood season in wet years when it is enriched in the midstream, exceeding upstream and downstream sections by 0.3-0.5 mg/L. Under the combined influence of natural factors and human activities, water quality in the river reach shows spatial and temporal heterogeneity. The study provides a modeling foundation and scientific basis for formulating effective water pollution control measures and water resource management strategies.更多还原