摘要
污水稀释因子(DF)用于描述污水排入受纳水体后被稀释的倍数,是污染物排放标准制定及其生态风险预测的重要指标.尽管河流DF的相关报道较多,但对DF计算方法的合理性讨论尚存不足.基于黄河流域235个水文站点、544个城镇污水处理厂和子流域数据集,分析了DF的不同计算方法对其数据结果的影响.结果表明,DF受子流域面积划分的显著影响,未设置子流域范围时,即污水在全境汇流,DF显著降低.当子流域面积超过3 000 m^(2)时,DF与流量呈显著相关性.根据设置子流域的计算结果,黄河流域干流、三级、四级和五级河流的DF中位数分别为6 358.8、28.5、21.5和5.1(无二级河流数据),上游、中游和下游的DF中位数为1 346.5、9.3和48.0,DF的空间变异大于时间变异.子流域面积在DF计算中较为关键,推荐通过污染物迁移转化模拟结合河流污染物实测浓度,判定子流域划分的合理性.研究可为区域尺度河流DF的确定及区域差异性排放标准的制定提供科学依据.
The dilution factor (DF) quantifies the extent to which wastewater is diluted after being discharged into a receiving water body. It serves as a critical indicator for establishing effluent discharge standards and assessing aquatic ecological risks. Although extensive research has been conducted on river DF, limited attention has been paid to the rationality of DF calculation methods. Typically, the accumulated wastewater volume (AWV) within a catchment—rather than the wastewater volume in the nearby receiving river—is commonly used for DF calculation. During this process, the delineation of the sub-catchment plays a critical role in determining AWV. However, the impact of sub-catchment delineation on DF calculation remains unclear. This study utilizes a comprehensive dataset comprising streamflow records from 235 hydrological stations, effluent discharge data from 544 municipal wastewater treatment plants (WWTPs), and sub-catchment information within the Yellow River Basin to examine the influence of sub-catchment delineation on DF. The results revealed that when the sub-catchment area was less than 3 000 m^(2), there was no significant correlation between DF and streamflow. However, this correlation became pronounced when the sub-catchment area ranged between 3 000 and 5 000 m^(2). This trend may have primarily resulted from the higher spatial heterogeneity in the distribution of WWTP within smaller sub-catchments compared to that within larger ones. Such heterogeneity led to greater variability in AWV and consequently in the DF. As the sub-catchment area increased, the spatial geographic elements such as number of WWTPs became more spatially homogenized, and the spatial distribution of geographic elements such as WWTPs became more homogeneous, resulting in more stable AWV estimates. This spatial averaging effect highlights the correlation between DF and streamflow in larger sub-catchments. When sub-catchment boundaries were not defined, and wastewater discharge was assumed to flow throughout the entire river network in the Yellow River Basin, the resulting DF was significantly underestimated. Using such underestimated DF values as basis for regulatory decision-making may lead to overly stringent effluent discharge standards that do not reflect actual environmental capacity. Therefore, accurate delineation of sub-catchment boundaries is essential. It is recommended that pollutant transport models be used in combination with observed pollutant concentration data in the river to determine an appropriate sub-catchment boundary. Based on DF results that incorporated sub-catchment boundaries, the median DF values were 6 358.8 for the main stream and 28.5, 21.5, and 5.1 for third-, fourth-, and fifth-order tributaries, respectively. Additionally, the median DF values for rivers in the upper, middle, and lower reaches of catchment were 1 346.5, 9.3, and 48, respectively. Notably, temporal variation in DF was much smaller than spatial variation. These findings provide valuable insights for applying DF at the regional scale and for developing region-specific effluent discharge standards.
作者
廖安然
陈卓
巫寅虎
陆韻
魏东斌
唐英才
高桦楠
廖梓童
胡洪营
LIAO An-ran;CHEN Zhuo;WU Yin-hu;LU Yun;WEI Dong-bin;TANG Ying-cai;GAO Hua-nan;LIAO Zi-tong;HU Hong-ying(State Key Laboratory of Regional Environment and Sustainability,Key Laboratory of Microorganism Application and Risk Control(MARC),Ministry of Ecology and Environment,School of Environment,Tsinghua University,Beijing 100084,China;Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,Beijing 100085,China)
出处
《环境科学》
北大核心
2026年第3期1665-1674,共10页
Environmental Science
基金
国家自然科学基金重大项目(52293440,52293442)
黄河流域生态保护和高质量发展联合研究项目(2022-YRUC-01-0405-05)。
关键词
稀释因子(DF)
黄河流域
城镇污水处理厂
排放量
排放标准
环境浓度
dilution factor(DF)
Yellow River Basin
municipal wastewater treatment plants
effluent volume
effluent discharge standard
environmental concentration
