洱海湖滨带挺水植物对湖体水环境影响及收割参数研究

安徽农业大学硕士学位论文洱海湖滨带挺水植物对湖体水环境影响及收割参数研究姓名：叶碧碧申请学位级别：硕士专业：环境工程指导教师：曹德菊2011-06I摘要挺水植物是湖泊生态系统的重要组成部分，在对水体的净化、增加湖泊的景观效果等过程中起到重要的作用。本文通过对挺水植物的生长特征以及生长和衰亡过程中对水环境影响的研究，结合对全湖挺水植物现分布状况进行调查，初步探讨挺水植物腐解对湖体营养物的贡献。针对湖滨带挺水植物在生长中期的生长过去茂盛的现象，开展了不同月份、不同频次及不同位置的收割室外模拟和现场实验，考察收割后挺水的恢复生长状况以及收割对水环境和群落的影响，初步探讨挺水植物收割的昀佳关键参数。主要结果如下：1.洱海全湖挺水植物现昀大总生物量为2563.5吨；其群落构成中以茭草为优势种（62.5%），芦苇（17.5%）和香蒲（11.3%）均具有一定的分布面积。不同挺水植物在生长过程中，茭草、芦苇3月开始萌芽，4-6月快速生长，8月达到稳定，11月开始衰亡；香蒲1月开始萌发，7月生物量达到昀大，9-10月开始衰亡；挺水植物的平均生物量在8月份达到昀大。2.挺水植物在生长过程中，其4-6月（生长快速时期）对藻的抑制效果明显，且对TN具有较好的去除效果，随着生长逐渐进入稳定期，7月后抑藻效果及对TN的吸收能力均有所下降。3.挺水植物在腐解过程中，水葱腐解速率昀快，茭草和香蒲其次，芦苇腐解速率昀慢；挺水植物单位干物质总氮释放量表现为：水葱茭草、香蒲芦苇，总磷释放量表现为：水葱茭草香蒲芦苇；而且，4种植物的总磷腐解率均高于总氮，腐解出的总磷进入水体的比例也明显高于总氮。在此腐解过程中，水体中TN、TP及COD的浓度均在腐解初期（1-3d）快速上升，pH，DO快速下降，随后，TN、TP、COD浓度均缓慢下降，pH，DO则缓慢回升。结合洱海湖滨带挺水植物空间分布的调查结果，估算全湖4种挺水植物总氮、总磷的总含量分别为17.6t和2.88t，短期内在水体中腐解总氮、总磷的释放总量分别为6.19t和1.12t，其中进入水体的总氮、总磷分别为2.58t和0.89t。4.通过收割对湖滨带水质具有明显的改善作用。其8月和10月对茭草进行收割，经47d左右完成再生长，但10月份收割较8月份收割后茭草再生长昀大速率下降29.6%、再生株叶长和直径分别下降26.9%、25.9%，8月份收割更有利茭草的再生长；II八月份对浅水区（15cm）沿泥上30cm处及以上位置收割更有利茭草的恢复生长（再生率为93.4%）；对深水区（50cm）沿水平面收割更有利茭草的恢复生长（再生率为100%）；重复收割对茭草的再生长有抑制作用，8月和10月对同一片茭草进行重复收割，其恢复生长昀大速率比单次8月收割下降37.1%，比单次10月份收割下降10.6%，收割管理应以单次收割为宜。11月对挺水植物收割后，使得来年在生长茭草植株密度增加、直径和株高下降、单位面积生物量未发生改变；8月和11月对挺水植物进行收割，收割区物种的多样性均没有发生明显的变化。关键词：洱海挺水植物腐解收割参数IIIAbstractEmergentplantsisanimportantcomponentoftheecosystem,itplaysanimportantroleintheprocessofpurificatedthequlityofwaterandincreasedtheeffectsoflandscapeforlakeshore.Thisarticlecarriedoutsimulationandfieldexperimentindifferentmonths,differentharvestingfrequencyanddifferentpositionsoftheharvest,basedonthestudyoftheemergentplantgrowthcharacteristicsandtheimpacttowaterenvironmentintheprogressofgrowthanddecayandcombinedwiththesurveyofdistributionwithemergentplantfromthewholelakeshore,tostudytheregrowsstatusoftheemergentplantandtheimpactonthewaterenvironmenafterharvestwhichwastostudyprimarilythekeyparametersofemergentplantharvesting.Themainresultswereasfollows.1.Thetotalbiomassofemergentplantsinthewholelakeshorewas2563.5tons,theZ.caduciflorawasthedominantspeciesintheircommunitiesconstitute(62.5%),P.australis(17.5%)andT.latifolia(11.3%)alsohadacertaindistributionarea.ZizaniacaducifloraandPhragnitesaustralisbegantogerminateinMarch，fast-growingduringApriltoJune,stableinAugust,begantodeclineinNovember.ThebiomassofTyphalatifoliaattainedtomaximuminJulyandbegantodeclineinSeptember.2.Inthegoocessprocessofemergentplants,IthassignificantlyinhibitoryeffecttothealgaeanddegradationeffecttoTNduringtheperiod(April-June)ofrapidgrowthforemergentplants,andwiththegradualgoowthintothestablephase,theeffectsdecreasedinJuly.3.ThedecompositionrateofS.validuswasthelargestamongtheseaquaticplants,andthenextwasthatofZ.caducifloraandT.latifolia,theslowestwasthatofP.australisduringthedecompositionprocesses.Theorderoftotalnitrogenamountsreleasedfromfouraquaticplants(perdryweight)wasS.validus,Z.caduciflora/T.latifoliaandP.australisandtheorderoftotalphosphorusamountsreleasedwasS.validus,Z.caduciflora,T.latifoliaandP.australis.Inthedecompositionprocess,Theconcentrationsoftotalnitrogen,totalphosphorusandCODincreasedrapidlyduringtheinitialstageoftheseplantsdecompositionprocesses,andthentheydecreasedslowly.However,thevaluesofpHandDOdecreasedquicklyduringtheinitialstage,andthenincreasedslowly.Combingspatialdistributioninvestigationofemergentaquaticplantsinthelakeshore,totalnitrogenandtotalphosphorusloadsreleasedformtheseemergentaquaticplantsindecompositionofthelakeshorewasestimated.Thepercentageofnitrogendecomposedwashigherthanthatofphosphorus,andtheproportionofdecomposedphosphorusenteredinwaterwashigherthanthatofnitrogen.TheamountsoftotalnitrogenandtotalphosphoruscontainedinfouraquaticplantsinthelakeshoreofLakeErhaiis17.6tand2.88t.Theamountoftotalnitrogenandtotalphosphorusdecomposedfromtheseplantswas6.19tand1.12tand2.58tand0.89tenteredintowateraftershorttermdecomposition.4.Ithadsignificantlyeffecttoimprovethewaterqualitybyemergentplantsharversting.AugustwasbetterforregenerationofZ.Caduciflora.inOctober，comparedwithAugust，regenerationratewasdecrease29.6%，thelengthanddiameterofregenerationplantrespectivelydecrease26.9%and25.9%.RepeatharvesthadinhibitingIVeffecttosubject，comparedwithAugustandOctobersinglecutting，maximumregenerationratioofrepeatedcuttingforthesamepiecesofexperimentquadrathaddecrease37.1%and10.6%.thus,harvestmanagementshouldbebasedonsinglecutting.onthephytalzone(depthofwater15cm),bestcuttingpositionofZ.caduciflorawas30cmabovesludge，whichhadtheregenerationrateof93.4%.ontheprofundalzone(depthofwater50cm),alongwithwaterlevelwasbetter，theregenerationratewas100%.Inthecomingyear,theplants’densityincreased,diameterandheightdecreased,biomassdidnotchangeaftertheNovemberharvestofZ.caduciflora.ThediversityofemergentplantshadnosignificantchangesafterAugustandNovemberharvest.Keyword：Erhai,Emergentplants,Decomposition,Harverst,ParametersV术语与略语表术语及略语英文全称中文全称mgmiligram毫克ggram克cconcentration浓度mLmililitre毫升Llitre升minminute分钟hhour小时dday天CODchemicaloxygendemand化学需氧量DOdissolvedoxygen