简介：Thirteensedimentcoresamples(0-10cm)weretakenfromthesevenlakesinthemiddleandlowerreachesoftheYangtzeRivertodeterminethecontentsanddistributionsoforganicphosphorus(P)fractionsinthesedimentsoftheshallowlakesinthearea.TheorganicPfractionsinthesedimentswereintheorderofmoderatelylabileorganicP(MLOP)>moderatelyresistantorganicP(MROP)>highlyresistantorganicP(HROP)>labileorganicP(LOP),withaverageproportionalratiosof13.2:2.8:1.3:1.0.LOP,MLOP,andMROPweresignificantlyrelatedtothecontentsoftotalorganiccarbon(TOC),water-solubleP(WSP),algal-availableP(AAP),NaHCO3-extractableP(Olsen-P),totalP(TP),organicP(OP),andinorganicP(IP).However,HROPwassignificantlyrelatedtoOPandweaklycorrelatedwithTOC,WSP,AAP,Olsen-P,TPorIP.ThissuggestedthatorganicP,especiallyLOPandMLOPinsediments,deservedevengreaterattentionthanIPinregardstolakeeutrophication.IntermsoforganicP,sedimentsweremorehazardousthansoilsinlakeeutrophication.AlthoughOPconcentrationswerehigherinmoderatelypollutedsedimentthanthoseinheavilypollutedsediment,LOPandMLOPwerehigherintheheavilypollutedsediment,whichindicatedthatheavilypollutedsedimentwasmorehazardousthanmoderatelypollutedsedimentinlakeeutrophication.

简介：TaihuLakeregionisoneofthemostindustrializedareasinChina,andthesurfacewaterisprogressivelysusceptibletoanthropogenicpollution.Thephysicochemicalparametersofsurfacewaterqualityweredeterminedat20samplingsitesinTaihuLakeregion,Chinainspring,summer,autumn,andwinterseasonsof2005-2006toassesstheeffectofhumanactivitiesonthesurfacewaterquality.Principalcomponentanalysis(PCA)andclusteranalysis(CA)wereusedtoidentifycharacteristicsofthewaterqualityinthestudiedwaterbodies.PCAextractedthefirstthreeprincipalcomponents(PCs),explaining80.84%ofthetotalvarianceoftherawdata.Especially,PC1(38.91%)wasassociatedwithNH4-N,totalN,solublereactivephosphorus,andtotalP.PC2(22.70%)wascharacterizedbyNO3-Nandtemperature.PC3(19.23%)wasmainlyassociatedwithpHanddissolvedorganiccarbon.CAshowedthatstreamswereinfluencedbyurbanresidentialsubsistenceandlivestockfarmingcontributedsignificantlytoPC1throughouttheyear.ThestreamsinfluencedbyfarmlandrunoffcontributedmosttoPC2inspringandwintercomparedwithotherstreams.PC3wasaffectedmainlybyaquicultureinspring,ruralresidentialsubsistenceinsummer,andlivestockfarminginfallandwinterseasons.FurtheranalysesshowedthatfarmlandscontributedsignificantlytonitrogenpollutionofTaihuLake,whileurbanresidentialsubsistenceandlivestockfarmingalsopollutedwaterqualityofTaihuLakeinrainyseason.TheresultswouldbehelpfulfortheauthoritiestotakesoundactionsforaneffectivemanagementofwaterqualityinTaihuLakeregion.

简介：土壤营养素的土壤侵蚀和损失是在西南中国的关键环境威胁。土壤质量上的土地使用和它的影响继续加亮。现在的学习被进行在四种陆地使用类型下面比较土壤侵蚀(即，林地，放弃的农田，耕种，和草地)并且他们土壤上的效果器官的碳(SOC)，全部的氮(TN)和在达恩奇·莱克分水岭的Shuanglong集水的全部的磷(TP)，中国。处于侵蚀率有大变化，越过四块陆地的滋养的分布使用类型。侵蚀率由137C平均2在在非栽培的地点的侵蚀率上的耕种和放弃的农田下面的133tkm−2年−1，和草地显示出网免职。为所有地点，滋养的内容基本上与土壤深度减少了。与耕种和放弃的农田相比，草地在0–40厘米土壤层以内有最高的SOC和TN内容，由林地列在后面。在137C，SOC和TN被观察。侵蚀在耕种引起的滋养的损失最高。这些结果建议因为他们由土壤侵蚀减少营养素的损失的能力，那块草地和林地将为在长期的经期上的SOC和TN隐遁是有益的。我们的学习证明在红土壤区域的滋养的损失的那减小能通过管理得好的植被恢复措施被做。

简介：AsoneofthedevelopingcountriesChinahasanarablelandpercapitafarbelowtheworld'saveragelevel.Withahigh-densitypopulationanthequickdevelopmentofeconomyandurbaniztion,theYangtzeRiverDeltashowsthetypicalcharacteristicsoflanduseindevelopedregionsofChina,whichare:highlandreclamationrateandlowarablelandpercapita;intensivelanduseandhighoutputvalue;andrapidincreasingofconstructionlandareaandfastdiminishingofarableland.TheanalysisindicatesthattheprocessofthearablelandchangesintheYangtzeRiverDeltacouldbedividedintofourdifferentchangestagesoverthepast50years.

简介：二年的溶度计研究被进行学习不同化肥的效果并且在由从东廷·莱克区域认为三是稻土壤的主要类型收割系统的双米饭在氮沥滤上玷污损失。结果证明在leachate的N集中没在脲，控制版本N化肥和猪粪肥的处理之中显著地不同并且所有这些化肥生产了更高全部的氮(TN)在与没有化肥被使用的盒子相比的leachate的集中。沥滤的TN损失追随者脲处理占了2.28%，0.66%，和在冲积的沙的卢拇的稻土壤(ASL)使用的N的1.50%数量，紫色石灰质的粘土似的稻土壤(PCC)，和微红黄的卢拇的稻土壤(RYL)分别地。更高的TN损失被发现与RYL相比在ASL与增加的leachate体积被相关，并且最低TN损失在PCC，最低leachate体积和TN集中在被观察被观察。器官的N和NH+4-NN的主要形式通过leachate被弄空，为56.8%TN损失和39.7%的财务分别地。因此，土壤特定的授精政体被推荐；特别地，化肥的最大的数量应该与高渗入率为沙的土壤被优化。为了避免沥滤的高N，从稻田，象脲那样的器官的N化肥或涂的脲的损失应该首先被用于表面顶肥或浅层的申请并且不为深层的申请。

简介：Landscapechangesweretracedoverthe20yearsfrom1974to1995intheupperMinjiangRiverbasin,oneofthemostimportantforestregionsinChina,basedonsatelliteimageinterpretationtoprovidebasicdataforlocaldecision-makingaswellassustainablelandscapeuseandmanagement.Resultsrevealedthatlandscapefrom1974to1995changedattheregionalscaleastheareaofforestlanddecreased,whilecropland,shrubland,economicforest,grassland,andbuilt-uplandincreased.Landscapechangesmainlyoccurredinforestland,shrubland,grassland,economicforest,andbuilt-upland.Moreover,thechangesamongforestland,shrubland,andgrasslandwerethelargest,influencingthewholecharacteristicsofthechangesinthebasin.Analysisofthechangesbetween1974and1995inthestudyareaindicatedthatlandscapeheterogeneityandfragmentationincreased,whereaslandscapeconnectivitydecreased.Thereweremultiplereasonsforlandscapechanges.Aprincipalcomponentanalysis(PCA)wasusedtoquantitativelystudydrivingforcesoflandscapechanges.ThePCAresultsshowedthateconomicandpopulationfactorsweretheprincipaldrivingforcesoflandscapechangesfrom1974to1995intheupperMinjiangRiverbasin,andthatPCAwasasuitablemethodforinvestigatingdrivingforcesoflandscapechanges.

简介：ThereasonsfortheYangtzeRiverfloodcalamityin1998arebrieflyintroduced.Theauthorsbelievethatusinga'soilreservoir'conceptisanimportantmeanstohelpcontrolfloodingoftheYangtzeRiver.A'soilreservoir'hasalargepotentialstoragecapacityanditswatercanberapidly'discharged'intotheundergroundwaterinatimelyfashion.Theeroded,infertilesoilsoftheYangtzeRiverWatershedarecurrentlyanobstacletoefficientoperationofthe'soilreservoir'.Thestoragecapacityofthis'soilreservoir'hasbeenseverelyhamperedduetointensivesoilerosionandtheformationofsoilcrusts.Therefore,possiblemeasurestocontrolfloodsintheYangtzeRiverWatershedinclude:rehabilitatingthevegetationtopreservesoilandwaterontheerodedinfertilesoils,enhancinginfiltrationofthedifferentsoiltypes,andutilizingthelarge'soilreservoir'oftheupperreachesoftheYangtzeRiver.

简介：在东南亚洲的蔬菜生产经常是依次与充满的米饭。有充满的大米生产的土壤的puddling可以为干燥土地庄稼的随后的生产导致不利土壤条件。为了证实永久蔬菜生产是否导致赞成土壤，在充满的大米在一个2年的地实验被学习以后，在土壤性质上与充满的大米依次为蔬菜，五个不同永久蔬菜生产系统的效果和蔬菜生产的一个系统调节。在0.05–0.10m深度层的体积密度与充满的米饭依次与永久蔬菜生产和蔬菜生产减少了。减少大批，密度被器官的粪肥和米饭外壳的申请影响，并且特别由庄稼的数字栽培了建议土壤耕种的那频率穿上主要效果体积密度。在在有提起的床的建设的联合，充满的米饭能在土壤结构上减少或完全消除puddling的否定效果以后，与公牛拖拉耕作。在0.15–0.20m土壤深度的体积密度没被影响。土壤酸味在所有系统显著地减少了。器官的碳在所有系统增加了的土壤，而是重要增加仅仅在二个永久蔬菜生产系统被发现。可得到的磷(P)显著地在二个永久蔬菜生产系统增加了，与一断然，到P的数量的关联适用。重要减少大批在pH的密度和增加(H2O)在仅仅2年以后，证明在充满的米饭以后的土壤条件能在集中的蔬菜下面在一短时间被改进生产。

简介：Soilsalinityandhydrologicdatasetswereassembledtoanalyzethespatio-temporalvariabilityofsalinizationinFengqiuCounty,HenanProvince,China,inthealluvialplainofthelowerreachesoftheYellowRiver.Thesalinesoilandgroundwaterdepthdataofthecountyin1981wereobtainedtoserveasahistoricalreference.Electricalconductivity(EC)of293surfacesoilsamplestakenfrom2km×2kmgridsin2007and40soilprofilesacquiredin2008wasanalyzedandusedforcomparativemapping.OrdinarykrigingwasappliedtopredictECatunobservedlocationstoderivethehorizontalandverticaldistributionpatternsandvariationofsoilsalinity.Groundwatertabledatafrom22observationwellsin2008werecollectedandusedasinputforregressionkrigingtopredictthemaximumgroundwaterdepthofthecountyin2008.ChangesinthegroundwaterlevelofFengqiuCountyin27yearsfrom1981to2008wascalculated.Twoquantitativecriteria,themeanerrororbias(ME)andthemeansquarederror(MSE),werecomputedtoassesstheestimationaccuracyofthekrigingpredictions.Theresultsdemonstratedthatthesoilsalinityintheuppersoillayersdecreaseddramaticallyandthetaxonomicallydefinedsalinesoilswerepresentonlyinafewmicro-landscapesafter27years.Presently,thesoilswithrelativelyelevatedsaltcontentweremainlydistributedindepressionsalongtheYellowRiverbed.Thereductioninsurfacesoilsalinitycorrespondedtothelocationswithdeepenedmaximumgroundwaterdepth.Itcouldbeconcludedthatgroundwatertablerecessionallowedwatertomovedeeperintothesoilprofile,transportingsaltswithit,andthusplayedanimportantroleinreducingsoilsalinityinthisregion.Accumulationofsaltsinthesoilprofilesatvariousdepthsbelowthesurfaceindicatedthatsecondarysoilsalinizationwouldoccurwhenthegroundwaterwasnotcontrolledatasafedepth.