北京市延庆县2016高考英语暑假阅读理解选练(8)阅读下列四篇短文,从每小题后所给的A,B,C或D四个选项中,选出最佳选项
Riversmaybeasignificantsourceofthegreenhousegasnitrousoxide(一氧化二氮),scientistsnowfind
TheircalculationsuggeststhatacrosstheglobethewaterwayscontributethreetimestheamountofnitrousoxidetotheatmosphereashadbeenestimatedbytheInternationalPanelonClimateChange(IPCC),theUnitedNationsscientificbodychargedwithreviewingclimatechangeresearch
Theyfoundthattheamountofnitrousoxideproducedinstreamsisrelatedtohumanactivitiesthatreleasenitrogen(氮)intotheenvironment,suchasfertilizeruseandsewagedischarges
“Humanactivities,includingfossilfuelcombustionandintensiveagriculture,haveincreasedtheavailabilityofnitrogenintheenvironment,”saidJakeBeaulieuoftheUniversityofNotreDameandtheU
EnvironmentalProtectionAgencyinCincinnati,Ohio,andleadauthorofthepape