不同水力负荷对两种生态沟渠内沉水植物苦草净化效果的影响研究  

Influence of different hydraulic load rates on the purification performance of submerged macrophyte Vallisneria natans in two vegetated drainage ditch types

作　　者：蔡敏 崔娜欣 张旭 陈桂发[1,2] 周丽 邹国燕 CAI Min;CUI Naxin;ZHANG Xu;CHEN Guifa;ZHOU Li;ZOU Guoyan(Eco-environmental Protection Research Institute,Shanghai Academy of Agricultural Science,Shanghai 201403,China;Shanghai Engineering Research Center of Low-carbon Agriculture(SERCLA),Shanghai 201415,China)

机构地区：[1]上海市农业科学院生态环境保护研究所,上海201403 [2]上海低碳农业工程技术研究中心,上海201415

出　　处：《农业环境科学学报》2024年第7期1621-1631,共11页Journal of Agro-Environment Science

基　　金：上海市2022年度“科技创新行动计划”国内科技合作项目(22015821200);国家重点研发计划项目(2021YFC3201503-02);长江生态环境保护修复联合研究二期项目(2022-LHYJ-02-0304);上海市农业科学院卓越团队建设计划项目(沪农科卓2022-023)。

摘　　要：利用农业灌排系统改造建设生态沟渠是治理农田面源污染的重要技术措施,水生植物、填料及水力负荷等是影响沟渠净化效率的重要因素。本研究以沉水植物苦草(Vallisneria natans)沟渠和沸石+苦草沟渠为研究对象,分析了不同水力负荷(HLR)下两种沟渠对农田径流中氮磷污染物的净化效果差异,阐明了苦草对沟渠脱氮除磷的贡献及其主要影响因素。结果表明,不同HLR下沟渠对水体氮和磷浓度去除率分别为47.7%~66.0%和57.5%~77.1%,随HLR升高而降低;氮和磷单位面积去除率为305.3~1009.2 mg·m^(-2)·d^(-1)和17.8~66.7 mg·m^(-2)·d^(-1),随HLR升高而升高。HLR显著影响沟渠氮、磷净化效率(P<0.05),而沸石填料则影响较小(P>0.05)。与沟渠运行前相比,苦草的密度、叶长以及总生物量(干质量)分别增加5.9~7.0、1.8~2.3倍和4.0~5.0倍,低HLR下苦草生长更好。苦草叶片及根系的氮、磷和叶绿素含量与水体氮磷含量显著正相关(P<0.05)。苦草直接吸收去除氮和磷量分别为2674.4~3384.1mg·m^(-2)和579.6~673.9mg·m^(-2),对沟渠氮和磷去除的贡献分别为5.6%~19.9%和20.1%~65.0%,苦草吸收贡献率随HLR升高而降低,HLR是影响苦草直接吸收对沟渠氮、磷去除贡献的主要因素。综上,苦草沟渠可有效削减农田氮、磷流失,提高HLR虽然降低氮、磷浓度去除率,但能显著增加氮、磷截留量。沸石+苦草沟渠长期运行后,应及时更新沸石以保障沟渠内填料强化净化功能的发挥。因此,从浓度和通量两方面对生态沟渠净化效果进行综合评价对于优化沟渠设计和运行管理具有重要实践意义。Vegetated drainage ditches(VDD)originate from agricultural irrigation and drainage system,representing an important technology to effectively control the non-point source pollution in farmlands.Aquatic plants,substrates,and hydraulic loading rate(HLR)are important VDD purification efficiency-affecting factors.In this study,we investigated the nitrogen(N)and phosphorus(P)removal efficiencies in farmland runoff under different HLR levels in two VDD types,i.e.,drainage ditch planted with a submersed macrophyte(Vallisneria natans)(VDD)and that planted similarly with additional zeolite supplementation(ZVDD).We successfully elucidated how plant N and P uptake contributed to the corresponding N and P removal in VDD along with the main impacting factors.Our results indicated that the TN and TP concentration removal efficiency in the VDDs under different HLRs were 47.7%–66.0%and 57.5%–77.1%,respectively,which decreased with increasing HLRs.However,the areal TN and TP removal efficiencies in the VDDs varied between 305.3–1009.2 mg·m^(-2)·d^(-1) and 7.8–66.7 mg·m^(-2)·d^(-1),respectively,which increased with elevated HLRs.The HLR,rather than zeolite addition,significantly affected VDD N and P removal efficiencies(P<0.05).Compared with the plants at the beginning of the experiment,plant density,leaf length,and total biomass dry weight yielded a 5.9–7.0,1.8–2.3,and 4.0–5.0 fold increase,respectively.Moreover,we observed that V.natans grew better at low HLR.N,P,and chlorophyll concentrations in the V.natans leaves and roots significantly positively correlated with the VDD N and P content(P<0.05).The N and P amounts directly assimilated by V.natans were 2674.4–3384.1 mg·m^(-2) and 579.6–673.9 mg·m^(-2),respectively.The contribution of plant uptake to N and P removal was 5.6%–19.9%and 20.1%–65.0%,respectively,which decreased with increasing HLR.Our results indicated that HLR was the main factor affecting the contribution of plant uptake of V.natans to N and P removal in VDDs.Taken together,the drainag

关 键 词：农田径流 生态沟渠 沉水植物 填料 水力负荷 

分 类 号：X52[环境科学与工程—环境工程]