Department of Civil Engineering and Engineering Mechanics, Columbia University, 500 West 120(th) Street, 610 Mudd, New York, NY 10027, USA.
Department of Earth and Environmental Engineering, Columbia University, 500 West 120(th) Street, 918 Mudd, New York, NY 10027, USA.
Sci Total Environ. 2019 May 15;665:944-958. doi: 10.1016/j.scitotenv.2019.02.121. Epub 2019 Feb 10.
The objective of this study was to evaluate the impact of bioswales on nutrient pollution in an urban combined sewershed. This evaluation was based on two criteria: the ability of bioswales to (1) remove nutrient pollution from stormwater runoff directly and (2) decrease sewer overflow volumes, which indirectly reduces total sewershed nutrient pollution during a storm event. Bioswales' direct nutrient removal was determined by analyzing nitrogen and phosphorus levels in water samples at seven bioswales located in the Bronx, New York City (NYC) over 42 storm events, while a bioswale's indirect nutrient removal through combined sewer overflow reduction was estimated by quantifying water retention at one of the bioswales. The study results indicated that: 1) the bioswale retained about 40% of stormwater conveyed to it from a drainage area 231 times its size, 2) bioswales leach nutrients into the subsurface, and 3) nitrogen leaching from bioswales varied seasonally, while phosphorus leaching decreased steadily over the study period. Although the studied bioswales leached a median 1.3 kg nitrogen per year into the subsurface, they provided an aggregate decrease in watershed nutrient pollution, from 7.7 to 6 kg nitrogen per year, due to their reduction of combined sewer overflow via stormwater retention.
本研究旨在评估生物滞留设施对城市合流制排水系统中营养物污染的影响。该评估基于两个标准：生物滞留设施（1）直接去除雨水径流水体中的营养物污染，以及（2）减少污水溢流总量，从而在暴雨事件期间间接减少整个排水系统的营养物污染。通过分析位于纽约市布朗克斯区的七个生物滞留设施在 42 次暴雨事件中采集的水样中的氮和磷含量，确定了生物滞留设施的直接去除营养物能力，而通过减少合流制污水溢流来实现的间接去除营养物能力则通过量化一个生物滞留设施的蓄水能力来估算。研究结果表明：1）生物滞留设施可截留其所在排水区域 231 倍的暴雨径流水量的约 40%；2）生物滞留设施将营养物淋滤到地下；3）氮素的淋滤具有季节性变化，而磷素的淋滤则在研究期间呈稳步下降趋势。尽管研究中的生物滞留设施每年将 1.3 千克氮素淋滤到地下，但由于其通过雨水截留减少了合流制污水溢流，从而使流域的营养物污染总量从每年 7.7 千克减少到 6 千克。
