title: Agricultural runoff pollution control by a grassed swales coupled with wetland detention ponds system: a case study in Taihu Basin, China.
abstract: The performance of a field grassed swales (GSs) coupled with wetland detention ponds (WDPs) system was monitored under four typical rainfall events to assess its effectiveness on agricultural runoff pollution control in Taihu Basin, China. The results indicated that suspended solids (SS) derived from the flush process has significant influence on pollution loads in agricultural runoff. Determination of first flush effect (FFE) indicated that total suspended solids (TSS) and total phosphorus (TP) exhibited moderate FFE, while chemical oxygen demand (COD) and total nitrogen (TN) showed weak FFE. Average removal efficiencies of 83.5 ± 4.5, 65.3 ± 6.8, 91.6 ± 3.8, and 81.3 ± 5.8 % for TSS, COD, TN, and TP were achieved, respectively. The GSs played an important role in removing TSS and TP and acted as a pre-treatment process to prevent clogging of the subsequent WDPs. Particle size distributions (PSDs) analysis indicated that coarse particles larger than 75 μm accounted for 80 % by weight of the total particles in the runoff. GSs can effectively reduce coarse particles (≥75 μm) in runoff, while its removal efficiency for fine particles (<75 μm) was low, even minus results being recorded, especially for particles smaller than 25 μm. The length of GSs is a key factor in its performance. The WDPs can remove particles of all sizes by sedimentation. In addition, WDPs can improve water quality due to their buffering and dilution capacity during rainfall as well as their water purification ability during dry periods. Overall, the ecological system of GSs coupled with WDPs is an effective system for agricultural runoff pollution control.
authors.affiliation: College of Urban Construction, Nanjing Tech University, Nanjing, 211816, People's Republic of China.|UCD Dooge Centre for Water Resources Research, School of Civil Engineering, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Jinhui
authors.initials: J
authors.lastname: Zhao
authors.affiliation: UCD Dooge Centre for Water Resources Research, School of Civil Engineering, University College Dublin, Belfield, Dublin 4, Ireland. yaqian.zhao@ucd.ie.
authors.forename: Yaqian
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: School of Environmental Science and Engineering, Nanjing University of Information Science & Technology, Nanjing, China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zhao
authors.affiliation: College of Urban Construction, Nanjing Tech University, Nanjing, 211816, People's Republic of China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Jiang
mesh_terms: D000383:Agriculture; D057919:Biological Oxygen Demand Analysis; D002681:China; D004784:Environmental Monitoring / Q000379:methods; D052918:Environmental Restoration and Remediation / Q000379:methods*; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D006109:Poaceae; D061005:Ponds / Q000032:analysis; D011891:Rain; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014876:Water Pollution / Q000517:prevention & control*; D018508:Water Purification; D060753:Water Quality; D053833:Wetlands
chemical_list: D014874:Water Pollutants, Chemical; D010758:Phosphorus; D009584:Nitrogen
keywords: Agricultural runoff; Grassed swale; Nutrients; Particle size distributions; Removal efficiency; Wetland detention pond
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