考研英语#2016考研究生英语#阅读每日精选 湿地可长期吸收硝酸盐

在考研英语中，阅读分数可谓是占到了总分的半壁江山 ，正所谓“得阅读者得考研
”
。对于备考2016考研的同学们
，在平时的复习中一定要拓展阅读思路，各类话题都要关注 ，这样才能在整体上提升考研英语阅读水平！

湿地可长期吸收硝酸盐

Wetlandscreated20yearsagobetweentile-drainedagriculturalfieldsandtheEmbarrasRiverwererecentlyrevisitedforanewtwo-yearUniversityofIllinoisresearchproject.Resultsshowanoverall62percentnitrateremovalrateandlittleemission1ofnitrousoxide2,apotent3greenhousegas."Slowingdowntherateofflowofthewaterbyintercepting4itinthewetlandiswhathelpstoremovethenitrate,"saysMarkDavid,aUniversityofIllinoisbiogeochemistintheCollegeofAgricultural,ConsumerandEnvironmentalSciences."Thevegetationthatgrowsinthewetlanddoesn'tmakemuchofadifferencebecausethegrassesdon'ttakeupmuchnitrogen.It'sjustaboutslowingthewaterdownandallowingthemicrobesinthesediment5toeliminatethenitrate.Itgoesbackintotheairasharmlessnitrogengas."

Davidwasinvolvedwithresearchonthesesamewetlandsfrom1994-98butdidn'ttakeanymeasurementsafterthat.Hehasspentmuchofhiscareerstudyingtherunofffromtile-drainedfieldsandmethodstoreducelossesofnitrateandphosphorus.Therunoff,particularlynitrate,fromfieldsintheupperMississippiRiverbasin,isbelievedtobethemajorcauseofthehypoxiaintheGulf6ofMexico.

"TheUSDArequestedproposalsontheeffectivenessofwetlandsandwoodchipbioreactorstoreducenitratelossesfromfields,butwasalsoconcernedaboutgreenhousegasemissions7,"saysDavid.WorkingwithgraduatestudentandleadauthorTylerGroh,"Wefoundthegreenhousegasemissionswerereallyquitelow.Nitrousoxidewasnotaproblem.Theothergoodnewsisthatthisresearchconfirmsthatwetlandsreallydoworktoreducenitraterunoff,andtheyworklongterm."

Davidsaysthat,alongwithfertilizermanagement,covercrops,andbioreactors,wetlandsareanintegralpartoftheIllinoisNutrient8LossReductionStrategy.Buildingawetlandcostsaboutthesameasinstallingabioreactor.

OneofthereasonsDavidpreferswetlandstohelpsolvethenitrogenpollutionproblemisthattheyworkreasonablywellinthewinterwhenthewatertemperaturesarelow.