title: Combination system of full-scale constructed wetlands and wetland paddy fields to remove nitrogen and phosphorus from rural unregulated non-point sources.
abstract: Constructed wetlands (CWs) have been used effectively to remove nitrogen (N) and phosphorus (P) from non-point sources. Effluents of some CWs were, however, still with high N and P concentrations and remained to be pollution sources. Widely distributed paddy fields can be exploited to alleviate this concern. We were the first to investigate a combination system of three-level CWs with wetland paddy fields in a full scale to remove N and P from rural unregulated non-point sources. The removal efficiencies (REs) of CWs reached 57.3 % (37.4-75.1 %) for N and 76.3 % (62.0-98.4 %) for P. The CWs retained about 1,278 kg N ha(-1) year(-1) and 121 kg P ha(-1) year(-1). There was a notable seasonal change in REs of N and P, and the REs were different in different processing components of CWs. The removal rates of wetland paddy fields adopt "zero-drainage" water management according to local rainfall forecast and physiological water demand of crop growth reached 93.2 kg N ha(-1) year(-1) and 5.4 kg P ha(-1) year(-1). The rice season had higher potential in removing N and P than that in the wheat season. The whole combined system (0.56 ha CWs and 5.5 ha wetland paddy fields) removed 1,790 kg N year(-1) and 151 kg P year(-1), which were higher than those from CWs functioned alone. However, another 4.7-ha paddy fields were needed to fully remove the N and P in the effluents of CWs. The combination of CWs and paddy fields proved to be a more efficient nutrient removal system.
authors.affiliation: S tate Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
authors.forename: Haijun
authors.initials: H
authors.lastname: Sun
authors.forename: Hailin
authors.initials: H
authors.lastname: Zhang
authors.forename: Zhimin
authors.initials: Z
authors.lastname: Yu
authors.forename: Jiasen
authors.initials: J
authors.lastname: Wu
authors.forename: Peikun
authors.initials: P
authors.lastname: Jiang
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Yuan
authors.forename: Weiming
authors.initials: W
authors.lastname: Shi
mesh_terms: D000383:Agriculture; D001673:Biodegradation, Environmental; D002681:China; D052918:Environmental Restoration and Remediation / Q000379:methods*; D009584:Nitrogen / Q000378:metabolism*; D012275:Oryza / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism*; D012621:Seasons; D014874:Water Pollutants, Chemical / Q000378:metabolism*; D014877:Water Pollution, Chemical / Q000517:prevention & control*; D053833:Wetlands
chemical_list: D014874:Water Pollutants, Chemical; D010758:Phosphorus; D009584:Nitrogen