東アジア域における大気中222P濃度連続測定ネットワークと洋上の孤島における大気中222P濃度の後方流跡線解析

摘要

22Rn conventration at Beijing which is located on China Continent was 10-20Bq m-3, at Nagoya, which is located on edge of terre trial area was3-10Bqm-3andatHachijo-jimaandHateruma-jima,whicharesolitaryislandsinPacificOceanwas0.5-3 Bqm-3,respectiyely.The atmospheric222Rnconcentrationvariationweredifferentfrom sites.The222Rnconcentrationwasthelowest inthesummer andthehighestin the winter execeptNagoyawherethehighestwas observedintheautumnandthelowestinthespring.Diurnalvariationsweremeasuredat Beijing andNagoya.Incontrast,diurnalvaritionswerenotmeasuredbutseveral-daycyclevariations wereemeasuredat Hachijo-jimaand Hateruma-jima It was pointed out by this study tht he Several-day -cycle yariations at Hachijo -jima were dependent on synoptic-scale atmospheric disturbance. 222Rn concentration inc1used rapidly after cold frontpassed through Hachijo-jima,Backward trajectory analysis of the relationshipbetweenatmospheric222RnconcentrationsatHachijo-jimaandtransportpathwayofairmass indicates that airmasstransported from ChinndSiberiahashighconcentration222Rnandairmasstransportedfrom PacificOceanhaslowconcentration222Rn.Inwinter, atmospheric222Rn concentrationsatHachijo-jimais dependent on verticaltransportpathwwayratherthan horizontaltransportpathway.