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1、標(biāo)準(zhǔn)實用ANNEX CDESCRIPTIONS OF MAIN PROCESSESThis Annex contains the descriptions of the main processes determining POP environmental behavior used in the participating models.C.1. Gas/particle partitioningEVN-BETR and UK-MODELThegas-particlepartitioningisdescribedwiththehelpoftheFinizioAerosolPartition

2、coefficientKQA.It sdependenceon theoctanol-airpartitioncoefficientKoa isdepictedbythefollowing formula:KQA = 3.5· KoaThe fugacity capacity of the bulk air compartment can then be written as the sum of the gaseous and particle-bound chemical fraction:( 1 particles in air volume fraction)· Z

3、 air + (particles in air volume fraction)· K QA · Z airwhereair-1/() is the fugacity capacity in air;ZR·TT -corrected environmental temperature for annual mean of 90C;R - gas constant = 8.314 Pa3· m/mol K;Particles in air volume fraction- 2 · 10-11;Koa= Kow / K aw - 51616649

4、 for PCB 153 at the averaged ambient temperature T;Averaged ambient temperature= 9 C (base temperature).CliMoChemcited from Scheringer et al., 2003The gas/particle partitioning is calculated as follows Finizio et al., 1997:Kow8.23K partair 0. 55 lgK hThis equation is used to calculate the fraction P

5、hi, which indicates the particle-bound fraction of the substance. Phi-values range from 0-1.lg kpartair K partairKow2.23in (m3 /g)6 0.55 lgK hk partairtspPhitsp1 k partairParameterDescriptionNumeric valueReferencetspTotal suspended particles86. 10-6 g/m 3Bennett et al . 2001 onlymentionedPhiparticle

6、-bound fraction ofbetween 0-1substance文案大全標(biāo)準(zhǔn)實用KhHenrys law constantdepending on substance,See Chapter 3 and Annex BKowOctanol/water partitioningdepending on substance,coefficientSee Chapter 3 and Annex B文案大全標(biāo)準(zhǔn)實用G-CIEMSWhen Koa is not available as input:qa = 6 · 106 / ls ,KPwhere qa is dimension

7、less particle/gas partition coefficient andls is liquid vapour pressure. FinalKPpartitioningis calculatedwithTSPanddensityof aerosolparticlesinfugacityformat. Vapourpressure is temperature corrected when the temperature is different from 25C.Whenoa is available as input:KKqa =y · K oa / (1000),

8、where,qa isdimensionlessparticle/gaspartitioncoefficient,yisorganicmattermass fraction,Kandis the density of aerosol particles.(Note:G-CIEMS model cancalculateV/Ppartitioningfromonly molecularweight (for preliminaryassessment purpose)or fromoa.Two output 1 and 2 is presentedinChapter 4 as G-CIEMS-1

9、and G-KSIEMS-2).DEHM-POPThe gas-particle partitioning is calculated using the absorption model:K pTSP,(K pTSP1)whereisthefractionofcompound sorbed to particles,p isgas-particlepartitioningKcoefficient, and TSP is the total suspended particulate matter e.g.Falconer and Harner, 2000.Kpis calculated us

10、ing theoa approach:Klog K pm r log K oalog fom11 .91,where r is a constant expected to have a value close to +1 for equilibrium partitioning,moctanol-airpartitioningcoefficient,f om is the fractionof organic11.91 is a constant determined by the interceptbr = logf om 11.91 and Harner , 2000.Koa is th

11、ematterintheparticles,andFinizio et al., 1997,FalconerThe temperature dependentKoa is calculated using the expression:K oa (T )K oa (Tref )exp(Uoa ( 11 ),RTrefTwhereUoa istheinternalenergytemperature andKoa(T ref ) is the value ofofphasetransfer,R istheuniversalgasconstant,T istheKoa at the referenc

12、e temperatureTref Beyer et al., 2002.SimpleBoxcited from Brandes et al., 1996Air-aerosolpartitioncoefficientsare usuallynotknown.However, someinformationis frequentlyavailableon thefractionof thechemicalthatoccursin associationwith theaerosol phase.文案大全標(biāo)準(zhǔn)實用SimpleBox uses this information for the com

13、putations. A value for the fraction of the chemical thatis associated with the aerosol phase,FRassaerosol , can be entered directly, or estimated on the basisof the chemical's vapor pressure, according toJunge 1977. In this equation, the sub-cooled liquidvapour pressure should be used. For solid

14、s, a correction is applied according toMackay1991:文案大全標(biāo)準(zhǔn)實用IfS (substance is liquid):MELTINGPOINT < TEMPERATUREFRass aerosol S =CONST.URE (T ) + CONST.VAPORPRESSIfS (substance is solid):MELTINGPOINT > TEMPERATUREFRass aerosol S =CONST.MELTINGPOI NT)6 .79.(1VAPORPRESSTEMPERATUR E S + CONST.URE (

15、T ).ewitherosolS- fraction of the chemical in air that is associated with aerosol particles atFRassascale S - (A);VAPOR PRESSURE(T) - vapor pressure of the chemical at temperatureT at scale S Pa (A);MELTINGPOINT- melting point of the chemical K (A);CONST- constant Pa· m (C);- surface area of ae

16、rosol phase maerosol2 /mair3 (C); S- temperature at the air-water interface at scaleSK (A).TEMPERATUREwith the productCONSTset equal to 10-4 Pa.CAM/POPsIn theCAM/POPs model,the processof POP partitioningbetween thegas andparticulatephases inatmosphere isbased onJunge-Pankowadsorption model , 1977;,1

17、987 POP fractionJungePankowadsorbed on the atmospheric aerosol particles is given by:cPL0cwhere,- fraction of POPs adsorbed on aerosol particles;- aerosol surface area available for adsorption, m23aerosol/mair;P0L - liquid-phase saturation vapour pressure of pure compound, Pa;c - parameter that depe

18、nds on the thermodynamics of the adsorption process and surfaceproperties of the aerosol (Pa· cm).Junge s proposed value of the parameter c is 17.2 Pa· cm P, 1987;Falconer et al., 1994;ankowBidleman et al., 1998.The liquid vapour pressure,P0L, are derived from:log 10 PL0 mb ,Twhere the slo

19、pe () and the intercept () are estimated to calculate liquid vapour pressure of POPsmbwith changing air temperature Falconer et al. , 1995;Harner et al., 1996. Temperature dependenceof P0L for each congener can be seen in Table C.1.Table C.1.Liquid vapour pressure of PCBs as a function of air temper

20、aturePCB-153PCB-180slope, m47755042intercept, b12.8513.03文案大全標(biāo)準(zhǔn)實用Aerosolsurfacearea,iscalculatedbymultiplyingaerosolnumber densitybyitswetsurfacearea.文案大全標(biāo)準(zhǔn)實用MSCE-POPIn thecurrent model version (MSCE-POP 1) the characterization of POP partitioning between the gasand particulate phase ofa pollutantis

21、 performed using subcooled liquidvapour pressureol (Pa).pAccording to the Junge-Pankow adsorption model , 1977;, 1987POP fractionadsorbedJungePankowon the atmospheric aerosol particles equals to:cpolcwherec is the constant depending on thermodynamic parameters of adsorption process and onproperties

22、of aerosol particle surface. It assumedc= 0.17 Pa· m , 1977 forJungebackground aerosol;is the specific surface of aerosol particles, m2/m3. Assumed= 1.5· 10-4 Whitby,1978.The temperature dependence ofpol(Pa) is parameterized in the model by:0a P11T0eT,polpolwhereT0 = 283.15 K is the refere

23、nce temperature,T (K) is the ambient temperature,0ispol valuep olat reference temperature, andaP is the coefficient of temperature dependence. The values ofp0ol andP for considered PCB congeners used in the model are presented in Table C.2.aTable C.Coefficients2.of poltemperature dependence for thre

24、e PCB congeners used in MSCE-POP modelCongenerp0olaPPCB-286.43 ·10 39383PCB-1539.69 ·10 510995PCB-1801.67 ·10 511610At present the work on modification of the description of gas aerosol partitioning within MSCE-POPmodelisongoing.Theapproach usingtheoctanol-airpartitioningcoefficientab

25、sorptionmodelpresented in Falconer and Harner,2000 is tested. Under this approach POP fractionadsorbed onthe atmospheric aerosol particles is calculated as:K pTSP1K pTSPwherepistheparticle-gaspartitioningcoefficientandTSPis thetotalsuspendedparticleKconcentration(g m-3 ).Theconstantpis calculatedfor

26、 PCBs viaoa bythefollowingregressionKKequations Falconer and Harner,2000:logp = logoa + logfom 11.91,(experimental version - MSCE-POP 2)KKwhere Koa is the octanol/air partitioning coefficient andf om is the fraction of organic matter in theatmospheric aerosol involved in partitioning.The temperature

27、 dependence ofoa is parameterized in the model by:Ka K110TT 0K oae,K oawhere0isvalue at reference temperature, andK is the coefficient of temperature dependence.KoaoaKa文案大全標(biāo)準(zhǔn)實用The values of0K oa and a for considered PCB congeners used in the model are presented in Table C.3.Table C.3. Coefficients o

28、f Koa temperature dependence for three PCB congeners used in MSCE-POP modelCongenerK0 oaaKPCB-285.78 ·1088731PCB-1533.64 ·101010811PCB-1802.07 ·101110442C.2. Dry deposition of the particulate phaseEVN-BETR and UK-MODELThe intermedia transport of chemicals is described using D-values (

29、mol/Pa· h), which represent howfast advective and reactive/degradation processes are occurring. In the case of the air to surfaceexchange, the D-value defining dry particle deposition is:Dair-surface = Surface Area· Particles in air volume fraction· Vq · Z air· KQAKnowing th

30、ese values can help calculate the flux of a chemical entering a region and, thus, it samount in the compartment under study.Surface area - compartment specific;Particles in air volume fraction-210-11 ;Vq - dry deposition velocity = 10.8 m/h.CliMoChemcited from Scheringer et al., 2003Dry deposition t

31、o baresoila, water, vegetation-covered soilbdC gasA iPhi vdryC gasdtV gasParameterDescriptionNumeric ValueReferenceCgasconcentration of substance in gaseous phasePhiparticle-bound fraction of the substance (seebetween 0-1C.1.)vdryAiVgasdeposition rate Mackay and Paterson ,260 m/d1991Area, i = bareso

32、il,water, vegetation-coveredvariablesoilVolume of gaseous phasevariablea Iftheyearconsistsofexactlyfourseasonswithvaryingtemperatures,vdryfordepositiontobaresoilischangingtakingintoaccountthatinthecoldseason theatmosphereismore stableand thedepositionratethereforeissmaller.The springand fallvaluesar

33、einterpolationsbetween thesummer and wintervalues.vdrychanges as follows Wania and McLachlan , 2001:seasonvdry =wintervdry /2springvdry /1.5文案大全標(biāo)準(zhǔn)實用summervdryfallvdry/1.5b If the year consists of exactly four seasons with varying temperatures,vdry for deposition to vegetation-coveredsoil is changing

34、 taking into account that in the cold season the atmosphere is more stable and the depositionrate therefore is smaller. The spring and fall values are interpolations between the summer and winter values.vdry changes as follows Wania and McLachlan , 2001:seasonvdry=wintervdry/(2. VegGrass .VegCon .Ve

35、gDec+5+3)springvdry/(1.5. VegGrass+2.5 . VegCon+2. VegDec)summervdryfallvdry/(1.5. VegGrass+2.5 . VegCon+2. VegDec)The vegetationcoverconsistsofthreetypes:Grass,ConiferousForestand DeciduousForest.Thevariables VegGrass, VegCon and VegDec describe the fraction of the vegetation-covered soil occupied

36、by the different cover types. Their numeric value is between 0-1 and depends on the climatic zone.Dry deposition to vegetationdC gasAvegPhi vdryC gasdtVgasParameterCgasPhivdryAvegVgasDescriptionNumeric Valueconcentration of substance in gaseous phaseparticle-bound fraction of the substance (see C.1.

37、)between 0-1deposition ratevariable, depending on climaticzone*Area of vegetation (identical with Area of vegetation-variablecovered soil)Volume of gaseous phasevariable* - the model contains three types of vegetation. For each type, the deposition rate (vdry ) is different (seetable below). Dependi

38、ng on the composition of a climatic zone,vdry is calculated as follows:vdryifractiongrassi vdry grassfractiondeci vdrydecfractionconi vdryconParametervdry ivdry grassvdry decvdry confractiongrassifractiondecifractionconiDescriptionNumeric ValueReferencedeposition rate in climatic zone ideposition ra

39、te to grass55.92 m/dHorstmann anddeposition rate to deciduous forest447.6 m/dMcLachlan 1998deposition rate to coniferous forest43.2 m/dM? ller 2002fraction of grass of total vegetation in climatic zone ivariablefraction of deciduous forest of total vegetation invariableclimatic zone ifraction of con

40、iferous forest of total vegetation invariableclimatic zone iBecause ofincreasedstabilityoftheatmospherein thespring,falland winterseason,thedeposition rates vdrygrass, vdrydec and vdrycon are divided by 3 for the winterseason and by2 forthe springand fallseasons(giventhatthe yearconsistsof exactlyfo

41、urseasons with varyingtemperature Wania and McLachlan, 2001).文案大全標(biāo)準(zhǔn)實用G-CIEMSF = v Dep · (TSP/) · CparticleWhere F is mass flux of compound for this chemical,vDep is dry deposition velocity of particles,TSPis particulate concentration of weight/volume dimensionis density of aerosol particle

42、s,Cparticle is compound volumetric concentration in particles. Same value is used on all land and water surfaces.DEHM-POPThedry depositionofparticulatephase is calculatedasafluxgivenbytheatmosphericconcentrationtimesadepositionvelocity Christensen ,1997.The depositionvelocityis highlydependent on the meteorological conditions and the surface properties. The size of the particles isassumed to be 1m Christensen , 1997.Forunstableconditi

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