LAUSR

In this study, two lined bioretention systems were designed and installed in Chongqing University of Arts and Sciences. Totally 15 natural rainfall events were sampled for analysis from July 2015 to April 2017. Compared with the inflow samples, the outflow samples contained a lower concentration of pollutants and especially NH3–N. In the spring of 2017, the average removal rate of total nitrogen (TN), NH3–N, NO3–N, total phosphorus (TP), and PO4–P for two systems were 70.33%– 85.71%, 88.89%–96.15%, 21.13%–66.67%, 28.57%–66.67%, and 33.33%–66.67%, respectively, besides, the effluent met the class-III criteria specified in the Environmental Quality Standards for Surface Water (GB 3838-2002). In the summer of 2017, the content of NO3–N in the effluent nitrogen from two systems was the highest (61%–85%), while that of NH3–N was the lowest (5%–13%). However, the composition of effluent nitrogen was different in autumn, the effluent nitrogen had the lowest content of NH3–N (5%–26%) but the highest content of total organic nitrogen (TON) (58%–69%). The annual pollution load of nitrogen and phosphorus was decreased by 61.33%–94.62%. As shown by the correlation analysis, TN, and PO4–P both demonstrated a significantly negative correlation with temperature, while NH3–N was positively correlated with NH3–N concentration in the roof runoff (NH3–NR). The concentration of TP from the system I or PO4–P from system II was positively correlated with the interval dry days (IDD) and TP or PO4–P concentration in the roof runoff, respectively.