简介：Themechanismswhichcontrolsthefixationand/orreleaseofPinsedimentofanextremelyacidiclake(pH=2.0to3.0)anditsresponsetotheinfluenceofeutrophicurbanwastewaterwereinvestigated.Theresults,inthechemicalcomposition,inthemineralogyofthesedimentandinthematerialasobtainedfromsedimenttraps,showthatthelakesedimentsaremainlyvolcanicmaterialreflectingvolcanicfeaturesofthebasin.Thesedimentationratecalculatedforthelake(2.5×10~(-2)mgm~(-2)day~(-1))washigherthanthatobservedinothersimilarglaciallakesinbothAndeanPatagoniaandalsoelsewhereintheworld.TheTotalPhosphorusconcentrationinsedimentswashigherthanfiguresreportedbyotherauthorsforminingacidlakes,andthemainfractionofPwasfoundassociatedwithorganicmatter.TherewasnocontrolbyFeorAlonP,becausebothareinsolutionatpH<3.0.Itwasconcludedthatchangesinthenaturalinputofnutrients(derivativesofCopahuevolcanofluid,thedischargeofsewage,orbasinrun-off)areresponsibleforahighconcentrationofSRPandN-NH_4~+inthelake.LaboratoryexperimentsshowedthatsedimentshavenoabilitytoretainphosphorusandacontinuousreleaseofPfromthesedimentsintothewatercolumnwasobserved.TheassayswherethepHwasartificiallyincreasedshowedthatthePstillremainsinsolutionuntilatleastpH7.0.Itwasconcludedthatchangesinthenaturalinputofnutrientsdueto:1)thevolcanicfluids,2)theincreaseinsewagecharges,or3)surfacerunoffupstream,maintainahightrophicstatewithhighconcentrationsofdissolvedPandN-NH_4~+,althoughthethresholdofneutralpHinthelakeisexceeded.Thisstudywillenableabetterunderstandingaboutofthemechanismofrelease/fixationofphosphorusinacidicsedimentsinordertoassistinmakingdecisionsregardingtheconservationandmanagementofthisnaturalenvironment.

简介：Biogenicstabilizationprocessesthatresultintheformationofbiofilmsandinterparticle-networkscansignificantlyalterthetransportcharacteristicsoffinegrainedsedimentlayers.Theincreaseinthethresholdofsedimentmotioncanamounttouptoseveralhundredpercent.Whileplancticorganismsareinvolvedintheformationofdepositingflocsandtheearlystagesofconsolidation,thesecondaryconsolidationiscontrolledbymicrobialbreakdownprocesses,leadingtochangesinthemechanicalpropertiesofcohesivesediments.Whiletheprimarystageofconsolidationiscompletedindays,thesecondaryprocessescanlastfordecades.Apreliminaryseriesoferosiontestsinanannularflumerevealeddemonstratedthebiogenicimpactintheearlystagesofsedimentformation.Surrogatematerialswereusedtosimulatethegoverningpropertiesofnaturalsoftsediments.

简介：这份报纸由域调查，核心观察和SEM分析讨论生长阶段，空间结构，在各种各样的参数之中的量的适合关系，生长模式和泥裂缝的影响因素。学习显示出那：(1)泥裂缝生长能通过三个阶段，即syndiagenetic阶段，埋葬diagenetic阶段(包括早diagenetic舞台，中间迟了的diagenetic舞台)并且epidiagenetic阶段。(2)在各种各样的参数之中的量的适合关系允许大意义描述泥的环境击碎的空间结构，地区性的分发和生长。(3)泥裂缝生长有三个模型，例如包括线性生长模式，曲线的生长模式和分叉的单方的生长模型生长模式，包括intersectional生长模式的多边的生长模型，join生长模式和驱散的生长模式，并且包括任何模式的联合的混合生长模型上面列出了。(4)现代的泥裂缝生长通常经历四个阶段。在沙泥的沙床有韵律的阶层能在裂缝生长上起一个润滑作用并且为充满裂缝提供足够沙的存款。(5)泥裂缝生长通常生产主要是120t的分叉和分叉角度???諤吗？？

简介：在台湾的Barlin水坝的失败，中国为在为快速的侵蚀和隧道恢复追随者建模评估概念提供重要案例研究故意、意外的水坝移动。我们使用了1D和quasi-2D的现在的建模努力解开了hydraulics和沉积模型(NETSTARS)建水坝评估discretization和parameterization怎么影响thefitofbedelevationpredictions到列在后面的观察失败。我们的分析评估了模型敏感到过去常定义剖面图的溪流试管的沉积运输功能，活跃的层厚度，和数字。结果显示那一)模型比到流试管的数字对活跃的层厚度和沉积运输功能更敏感，b)水坝移动模型的开发是可能的得益于及时改变活跃的层厚度，并且c)增加的侧面的discretization不看起来改善模型在我们的地点装入陡峭、很快改变的河环境。我们与之间的差别的讨论得出结论，识别对的需要，和1D的一般使用，quasi-2D，并且充分，2D在水坝移动和失败分析当模特儿。

简介：Phosphorus(P)fractionationandsorptionbehaviorwerestudiedinthesedimentsoftwocalcium-sulfate(Ca-SO4:Ca2t170mgL-1;SO42-400mgL-1)waterreservoirsinthesoutherncentralArgentineAndes-ElCarrizalReservoir(ECR),whichstratifiesinsummerandElNihuilReservoir(ENR),whichisverticallymixedthroughouttheyear.Sedimentsizeclassesreflectedthelithologyofbothbasinsandthereservoirsrelativelocation:ECR(downstreamfromavalleyadjacenttoamountainenvironment)hadhigherclayproportionswhilethesandfractionwasmoreimportantinENR(justnexttoamountainenvironment).Inbothreservoirs,thechemicalcompositionrevealedlowalterationandcalciumenrichment.TotalPcontentwasrelativelyhigh(1.1-1.6mgPkg-1dryweight)asexpectedfromthecontributionofmarineformations.PfractionationwasdominatedbyCa-P(ECR,69%andENR,63%)followedbyorganic-P(23%)insummer-anoxicECRandbyiron/aluminum(Fe/Al)-P(27%)inoxicENR.BatchexperimentsshowedthatsorptionbehaviorinECRhadatypicalLangmuirisothermplotwhileinENRthatmodelfittedonlyatlowdissolvedPvalues(o5mgPL-1)andco-precipitationevidencewasobservedathigherPconcentrations.ItisproposedthatlowerFe/Al-Pcontentinanoxic(ECR)vs.oxic(ENR)sedimentsresultsfromthePreleasedfromiron-boundphosphorusduetosulfatereduction-ferroussulfideformationinananoxicenvironment.ThisconditionshouldenableECRsedimentstoadsorbPintofreshoxidizediron,andENRsedimentstoco-precipitatePwithcalciumduetoFe/Al-Psaturation,asobservedinbatchexperiments.ThispaperconstitutesthefirstdescriptionofphosphoruscontentanddynamicsinreservoirsedimentsinaridcentralwesternArgentina,wherewatersulfateconcentrationsarenaturallyhighduetobasinlithology.