Chapter 4. Persistant toxic substances (PTS) sources and pathways

Transcription

1 Chpter 4 Persistnt toxic sustnces (PTS) sources nd pthwys

2 4.1. Introduction Chpter Introduction In generl, the humn environment is comintion of the physicl, chemicl, iologicl, socil nd culturl fctors tht ffect humn helth. It should e recognized tht exposure of humns to PTS cn, to certin extent, e dependnt on ech of these fctors. The precise role differs depending on the contminnt concerned, however, with respect to humn intke, the chin consisting of source pthwy iologicl vilility pplies to ll contminnts. Leving side the iologicl spect of the prolem, this chpter focuses on PTS sources, nd their physicl trnsport pthwys. Contminnt sources cn e provisionlly seprted into three ctegories: Distnt sources: Locted fr from receptor sites in the Arctic. Contminnts cn rech receptor res vi ir currents, riverine flow, nd ocen currents. During their trnsport, contminnts re ffected y the comined effects of physicl nd chemicl fctors. Persistence in the environment is, therefore, one of the most importnt chrcteristic in determining the ility of contminnts to rech the Arctic. In this respect, PTS, due to their low degrdtion rtes, re often considered to e glol contminnts suject to long-rnge trnsporttion. Locl sources: These re locted in receptor region, often in the vicinity of indigenous communities. Although trnsport of contminnts from locl sources to recipients is determined y the sme physicl nd chemicl processes s contminnts from distnt sources, there re wider rnge of pthwys nd mechnisms tht my e involved in the cse of locl sources. For exmple, mechnisms of soil contmintion from locl sources cn differ significntly, such tht effects of locl contmintion cn e much greter thn those resulting from contmintion from distnt sources. In contrst to distnt sources, locl sources cn lso ffect recipients through contmintion y more redily degrdle sustnces s well s the persistent contminnts. Although non-persistent contminnts re eyond the scope of this project, it is importnt to note tht the effects of PTS, when comined with those of other types of contminnts originting from locl sources, my e sustntilly incresed. Similrly, humns exposed to nd ffected y PTS my e more sensitive to the cute toxic effects of other less persistent contminnts from locl sources. Contct sources: These comprise the intentionl or unintentionl use of chemicls y recipients in everydy household nd occuptionl uses. For exmple, the helth of individuls using PTS-contining insecticides for pest control or for the tretment of reindeer my e directly ffected y the products. A typicl exmple of n unintentionl contct contminnt source would e the use of pints nd insulting mterils contining PTS in the indoor environment Assessment of distnt sources: Long-rnge tmospheric trnsport Due to the nture of tmospheric circultion, emission sources locted within the Northern Hemisphere, prticulrly those in Europe nd Asi, ply dominnt role in the contmintion of the Arctic. Given the sptil distriution of PTS emission sources, nd their potentil for glol trnsport, evlution of longrnge tmospheric trnsport of PTS to the Arctic region necessrily involves modeling on the hemispheric/glol scle using multi-comprtment pproch. To meet these requirements, pproprite modeling tools hve een developed. Extensive efforts were mde in the collection nd preprtion of input dt for modeling. This included the required meteorologicl nd geophysicl informtion, nd dt on the physicl nd chemicl properties of oth the selected sustnces nd of their emissions. It should e noted tht relile nd reltively comprehensive informtion on emission sources is currently not ville for most PTS. Therefore, n ssessment of long-rnge tmospheric trnsport ws undertken for sustnces for which emission source informtion is sufficient to meet modeling requirements, nmely, mercury (Hg), polychlorinted iphenyls (PCBs) nd γ-hexchlorocyclohexne (γ-hch). It ws considered tht modeling results otined for these contminnts could e extrpolted to give generl overview on the sitution with respect to long-rnge tmospheric trnsport of other PTS in the study. An ssessment of mercury, PCB nd γ-hch pollution rising from emission sources in the Northern Hemisphere nd ffecting regions of the Russin North inhited y indigenous peoples, ws crried out for the reference yer This ssessment included n evlution of ir concentrtions nd deposition levels, s well s source-receptor reltionships for selected regions nd for the Arctic s whole. Prticulr ttention ws given to the fte of contminnts in different environmentl comprtments (ir, soil, wter, etc.). The effect of PCBs nd γ-hch trnsport vi ocen currents, ice cover dynmics, nd Mercury Depletion Event (MDE) (Schroeder et l., 1998) chemistry on Arctic pollution were lso exmined Climte conditions nd tmospheric circultion ptterns The climte of the Russin Arctic is chrcterized y lck of solr rdition during the winter, which leds to very low tempertures. In contrst, solr rdition flux in the summer is significnt, ut tempertures re still not high, s most incoming solr energy is utilized in the melting of ice nd snow. Atmospheric circultion is chrcterized y cyclonic ctivity in ll sesons, which promotes the exchnge of ir msses etween the middle nd high ltitudes. As result of the previling westerly irflows, the Russin Arctic experiences the mod- 34

3 Chpter Assessment of distnt sources: Long-rnge tmospheric trnsport erting influence of the Atlntic (North Atlntic Current). This influence is stronger in western prts thn in centrl nd estern prts. The western Russin Arctic is therefore wrmer, with much lower temperture vrition etween winter nd summer thn tht found in the estern prt of the Russin North, which is chrcterized y the more severe climtic conditions. Atmospheric circultion in the Arctic region differs etween winter nd summer (Figure 4.1) with the previling tmospheric currents in the lower Arctic troposphere depending upon the loction of qusi-sttionry pressure systems in the Northern Hemisphere, the Icelndic nd Aleutin Lows, nd Sierin nd North Americn Highs. In winter, due to the geogrphicl position of these systems, ir msses move into the Arctic from Europe in northesterly direction, or from centrl Asi nd Sieri. Western regions of the Russin North Murmnsk Olst nd the Nenets Autonomous Okrug (AO) re ffected minly y southwesterly or westerly irflows, ringing ir msses from Estern nd Centrl Europe, s well s from centrl Russi. In the centrl regions Ymlo-Nenets AO, Tymir AO, nd the Repulic of Skh (Ykuti) southerly irflows previl, trnsporting ir msses from centrl Russi, the Urls, the south of Sieri nd centrl nd estern Asi. Over the esternmost region the Chukchi AO northerly irflows predominte in winter. Figure 4.1. Men position of the Arctic ir mss in Jnury nd July, nd the winter nd summer frequencies of winds (AMAP, 1997) Emission sources Emission sources of Hg, PCBs nd γ-hch were divided into severl groups ccording to their geogrphicl loction (Figure 4.2). The key criterion used for the selection of specific region s n ggregte emission source ws the possile influence of emissions from this region on the Russin North. In summer, the continentl high-pressure systems dispper nd ocenic low-pressure systems weken. Over the Arctic Ocen, high-pressure systems occur more frequently thn in winter, cusing n outflow of Arctic ir in the meridionl direction. The Europen region comes under the impct of the Azores nticyclone. Over centrl Eursi nd the centrl prt of North Americ, low-pressure systems dominte. The influx of ir msses to the Arctic minly occurs over the Aleutin Islnds/Bering Se region in the est, nd from the North Atlntic, long the north-western periphery of Azores nticyclone, in the west. Compred with winter, the northerly component is more frequent in tmospheric trnsport in summer cross ll regions of the Russin Arctic except for Chukotk. Chukotk, during the summer, is predominntly ffected y trnsport either from the Pcific Ocen, or from Estern Asi nd the Russin Fr Est, some trnsport from the north still occurs however. Atmospheric circultion is lso responsile for the precipittion pttern in the Russin Arctic. The most undnt nnul precipittion tkes plce in the western prt nd cn rech mm/y. Annul precipittion decreses from the west towrds the est, nd over the north of the Repulic of Skh (Ykuti) is minly within the rnge of mm/y. In the esternmost prt of the Russin Arctic, precipittion is reltively high ( mm/y), nd cused y the southerly trnsport of ir msses from the Pcific Ocen, especilly during summer. Figure 4.2. Source regions of the Northern Hemisphere considered in the source-receptor nlysis. The numer of the selected regions vries for different pollutnts. For simplicity, generlized nmes were used for some regions, e.g., the region identified s Centrl Asi ctully includes centrl, western, nd southern Asi. Selected emission sources regions for the pollutnts under considertion re presented in Tle 4.1. Source region oundries lso vry depending upon the contminnt in question. For exmple, Chin nd Jpn re con- 35

4 4.2. Assessment of distnt sources: Long-rnge tmospheric trnsport Chpter 4 sidered s seprte sources for mercury, ut included in lrger Asin source regions for the other contminnts. For γ-hch, Chin nd Indi re importnt enough sources to consider their emissions seprtely, wheres Northern Europe ws omitted s γ-hch emissions in this region in 1996 were insignificnt. The Americs (North nd Centrl) re included s single source region, due to their greter distnce from the Russin North. Mercury The industril nd urnized regions of the world ccount for the mjority of nthropogenic mercury emissions to the tmosphere. To evlute the nthropogenic input of mercury to the Northern Hemisphere, the most recently ville glol emission inventory, tht for 1995, (Pcyn nd Pcyn, 2002) ws used. The originl glol emissions dtset hs resolution of 1 x1 lt./long., with mercury emissions specited into three chemicl forms: gseous elementl mercury (Hg 0 ), gseous oxidized mercury (Hg 2+ ), nd prticulte mercury (Hg prt ). These emission dt were redistriuted to lower resolution (2.5 x2.5 ), suitle for input to the ir trnsport model employed, ssuming uniform distriution over ech grid cell. The most significnt emission sources re in Estern Asi, Europe nd the estern prt of North Americ. Considerle emissions lso occur in the Indin sucontinent nd the Arin Peninsul. The totl mount of nthropogenic mercury emissions in 1995 from the Northern Hemisphere ws estimted s 1887 tonnes. Tle 4.1. Regions of the Northern Hemisphere selected s source res for long-rnge trnsported pollutnts. Due to their proximity to the Russin North nd the significnt polluting influence of some regions of the Russin Federtion, the territory of Russi ws sudivided into twelve source regions ccording to current dministrtive oundries nd to their potentil impct on Arctic ecosystems. The Loction of these regions nd revited identifiction codes is shown in Figure 4.3. The first five regions (MUR, NEN, YNT, YAK, nd CHU) re lso considered s the receptor regions. In order to ssess the impct of different mercury emission sources on the contmintion of the Russin North, the entire hemispheric emission field ws divided into 11 regions: Russi, Chin, Centrl Asi, the Americs, Jpn, Southest Asi, Afric, Estern Europe, Western Europe, Southern Europe, nd Northern Europe. The reltive contriution of ech region to totl mercury emissions in the Northern Hemisphere is presented in Figure 4.4(). This digrm shows tht more thn one third (34%) of the totl mercury emissions originte in Chin. Considerle emissions lso originte in Centrl Asi (14%), the Americs (11%), Jpn (9%), nd Russi (8%). The contriution of other regions specified does not exceed 7%. Figure 4.4() shows totl mercury emissions from different regions of the Russin Federtion. The most significnt emission sources re locted in the Centrl- Chernozem, Volg, nd North-Cucsin regions (CVN), the Url region (URL), nd the Centrl nd Volgo-Vitsky regions (CVV). MUR Murmnsk Olst; NWK North-Western region nd Kliningrd Olst; NEN The Nenets AO; CVV Centrl nd Volgo-Vitsky regions; YNT The Ymlo-Nenets AO CVN Centrl-Chernozem, Volg nd Tymir AO; nd Northern Cucsus regions; YAK The Repulic of Skh (Ykuti); URL Url region; CHU The Chukchi AO; WSB West Sierin region; NRT Northern region; ESB Est Sierin nd Fr-Estern regions. Figure 4.3. Aggregted regions of the Russin Federtion chosen for source-receptor nlysis. The first five regions listed (MUR, NEN, YNT, YAK, nd CHU) re considered s oth source nd receptor regions, the rest re considered s source regions. Mercury emissions from nturl sources contriute significnt proportion of the totl mercury input to the tmosphere. Estimtes for the vlue of nturl emissions nd re-emissions were sed on literture survey. Mercury emissions from nturl sources were pportioned over the Northern Hemisphere on the sis of the nture of the underlying lnd/se surfce. Five surfce ctegories were distinguished: ice covered lnd (glciers, etc), sewter, soil developed from geochemicl mercury elts, soils in res of mercury deposits, nd other (ckground) soils. It ws ssumed tht there is zero mercury emission from ice cps/gl- 36

5 Chpter Assessment of distnt sources: Long-rnge tmospheric trnsport ciers. Nturl emissions from sewter were distriuted proportionlly to the ocen s primry production of cron. Emissions from soil re most significnt from soils occurring over mercury deposits nd lowest for ckground soils. In ddition, the temperture dependence of emission fluxes ws lso clculted, sed on dt otined through mesurements. PCBs Modeling long-rnge trnsport of individul PCB congeners to the Russin North ws mde using glol emission inventory concerning 22 individul PCB congeners covering the period (Breivik et l., 2002). This inventory is sed on estimtes of the glol production nd consumption of these PCBs in 114 countries (Breivik et l., 2002). The emissions were distriuted to the (2.5 x 2.5 lt./long.) model grid using (s proxy for emission distriution) 1990 popultion distriution dt set otined from the CGEIC wesite ( The totl glol production of PCBs from mounted to pproximtely 1.3 million tonnes. Almost 97% of intentionlly produced PCBs were used in the Northern Hemisphere. Emission dt for individul congeners for 1996 were used in ll model clcultions nd, ccording to the high emission scenrio discussed y Breivik et l. (2002), totl emissions of the 22 PCB congeners in the Northern Hemisphere in 1996 mounted to out 662 tonnes. Totl emissions of PCB- 28, -118, -153, nd -180 from the Northern Hemisphere Figure 4.4. () Contriution of different regions of the Northern Hemisphere to totl nthropogenic mercury emissions, () totl nthropogenic mercury emissions from different regions of the Russin Federtion. in 1996 were out 80, 23, 16, nd 4.5 tonnes, respectively. Congener composition of PCB emissions vries etween source regions. In order to study the contriutions of different source regions in the Northern Hemisphere to the contmintion of the receptor-regions in the Russin Arctic, six min regionl sources were identified, sed on the emission distriution: Russi, Northwest Europe, Southest Europe, the Americs, Southest Asi, nd Centrl Asi nd Afric. The mjor emission sources of PCBs in the Northern Hemisphere in 1996 were the Americs (24%), Russi (23%), Southest Europe (19%), nd Northwest Europe (16%) (Figure 4.5()). The min Russin emission sources re locted in Centrl- Chernozem, Volg nd North-Cucsus regions (CVN) s well s in Centrl nd Volgo-Vitsky regions (CVV) (Figure 4.5()). γ-hch The scenrio for γ-hch emissions in the Northern Hemisphere ws sed on officil dt sumitted to the UN ECE Secretrit in 2002 (Vestreng nd Klein, 2000) nd ville expert estimtes (Pcyn et l., 1999). In ddition, γ-hch emissions for from the Russin Federtion, nd some other countries in the Northern Hemisphere were estimted from informtion in rnge of literture sources (Revich et l., 1999, Yer-ooks, 1992, , Figure 4.5. () Contriution of different regions to PCB emissions (22 congeners) in the Northern Hemisphere for 1996, () PCB emissions (22 congeners) from different regions of the Russin Federtion in

6 4.2. Assessment of distnt sources: Long-rnge tmospheric trnsport Chpter 4 Anniev et l., 1990, Li et l., 1996, 1998,1999, nd Mcdonld et l., 2000) regrding the use of this insecticide. To estimte emissions from dt on insecticide use, the emission fctor for lindne in griculturl use (0.5) (Guideook, 1999) ws pplied. The resulting estimte for totl γ-hch emissions from the Northern Hemisphere in 1996 ws out 3445 tonnes. The sptil distriution of these γ-hch emissions in the Northern Hemisphere, for modeling purposes, ws mde using crop re s surrogte prmeter (Pcyn et l., 1999). To model long-rnge tmospheric trnsport of γ-hch to the Russin North, nine source regions were identified in the Northern Hemisphere: Russi, Western Europe, Estern Europe, Southern Europe, the Americs, Chin, Indi, the rest of Asi, nd Afric. Chin nd Indi were considered s individul source regions due to their high use of this insecticide compred to the rest of Asi. Estimtes of the contriution of min source regions to totl γ-hch emissions in the Northern Hemisphere in 1996, sed on the selected emission scenrio, is shown in Figure 4.6(). γ-hch emissions from Russin regions in 1996 re shown in Figure 4.6(). The min contriution to γ-hch emissions in the Northern Hemisphere, ws mde y Indi (53%) nd Western Europe (18%). The contriution from Russi is only 2%. Mjor Russin γ-hch emissions in 1996 originted from the Europen prt of the Russin Federtion. The highest Russin γ-hch contriutions were mde y sources locted in the Centrl-Chernozem, Volg nd North-Cucsin regions (CVN) Contmintion levels in the Arctic resulting from long-rnge tmospheric trnsport To evlute levels of contmintion of the Arctic region y glol pollutnts (mercury, PCBs, nd γ-hch) resulting from long-rnge tmospheric trnsport, hemispheric modeling pproch ws employed. For this purpose, the EMEP Meteorologicl Synthesizing Centre-Est (MSC-E) hve developed hemispheric multi-comprtment trnsport models MSCE-Hg-Hem nd MSCE-POP. Figure 4.6. () Contriution of different regions to γ-hch emission in the Northern Hemisphere for 1996, () γ-hch emissions from different regions of the Russin Federtion in Mercury, PCB nd γ-hch concentrtions in ir nd their deposition lods s evluted for the Northern Hemisphere nd the Arctic for 1996, re discussed elow in the relevnt susections. Prticulr ttention hs een given to tmospheric long-rnge trnsport to, nd deposition of these pollutnts in the Russin Arctic. For mercury, the effect of Mercury Depletion Event (MDE) chemistry on Arctic deposition ws considered. In ddition, for the ssessment of environmentl pollution y PCBs nd γ-hch, the role of trnsport vi se currents nd ice cover dynmics were tken into ccount. The mrine environment is prticulrly importnt in reltion to the trnsport nd fte of γ-hch. Chrcteristic vlues of men nnul ir concentrtions nd deposition fluxes of mercury, PCBs nd γ-hch over the Arctic re re summrized in Tle 4.2. The consistency of the modeling results ws verified y comprison with ville mesurements. Tle 4.2. Chrcteristic vlues of men nnul ir concentrtions nd nnul deposition fluxes for mercury, selected PCBs, nd µ-hch over the Arctic in Mercury Figure 4.7 shows the nnul deposition flux of mercury in the Northern Hemisphere. Highest deposition levels re in those regions with considerle emissions: i.e. Southest Asi, Europe, nd the estern prt of North Americ. For other res, the deposition pttern, to some extent, corresponds to nnul precipittion vlues, since wet deposition plys dominnt role in removing mercury from the tmosphere. From the model results, totl deposition over the Arctic region in 1996 mounted to 240 tonnes. The influence of MDEs on deposition fluxes within the Arctic region hs een the suject of considerle reserch in recent yers. The postulted MDE mechnism (Linderg et l., 2002) includes complicted 38

7 Chpter Assessment of distnt sources: Long-rnge tmospheric trnsport chemistry, involving the formtion of hlogen relted rdicls. The development of detiled model component for MDE chemistry is the suject of seprte study. For the purposes of this study, n ttempt ws mde to qulittively estimte the effect of MDE on Arctic Hg contmintion y using simplified set of prmeters. As illustrted in the enlrged pnel in Figure 4.7, even short-term phenomen such s MDEs, which occur during only few weeks of the yer, cn considerly increse the nnul deposition of mercury in some regions of the Arctic, in prticulr costl res. The influence of MDEs on totl nnul mercury deposition is illustrted in Figure 4.8(). Additionl contriutions of mercury s result of MDEs cn mount to more thn 50 percent of totl deposition vlues in res djcent to Arctic costs (i.e. within out 300 km of the cost inlnd nd offshore). These res include the Queen Elizeth Islnds, Hudson By, the White Se, the Gulf of the O river, nd the Lptev Se cost, mong others. Negtive vlues (for percentge increse in deposition due to MDEs) show tht incresed deposition fluxes due to MDEs in some regions, led to decresed fluxes in other res. A prt of the mercury trnsported y the ir therefore does not enter the High Arctic during springtime, due to it eing scvenged during MDEs over costl nd contiguous regions. Figure 4.8() shows the sesonl vrition in totl mercury deposition in the Arctic. The model predicts tht the most pronounced MDE effect is in My nd June (tking into ccount temporl shift due Figure 4.7. Annul deposition of totl mercury in the Northern Hemisphere. The enlrged pnel shows elevted mercury deposition over the Arctic cost due to MDEs. to the model prmeters used), when monthly deposition in the Arctic incresed two-fold or greter. The clcultions predict tht MDE re responsile for deposition of out 50 tonnes of mercury per yer in the Arctic out 20% of the totl nnul deposition. Due to the high trnsport potentil of mercury in the tmosphere, mny nthropogenic nd nturl sources from different regions of the Northern Hemisphere contriute to Arctic pollution. The contriution from Figure 4.8. () Influence of MDEs on totl nnul mercury deposition in the Arctic (re defined y the white (AMAP re) oundry), nd () sesonl vrition in totl mercury deposition to the Arctic with nd without MDEs. The figures present the difference etween two model computtionl runs one with nd one without MDEs included. Figure 4.9. Contriution of different source regions to the nnul deposition of mercury in the Arctic rising from () nthropogenic sources nd () nturl sources nd re-emissions. 39

8 4.2. Assessment of distnt sources: Long-rnge tmospheric trnsport Chpter 4 the vrious regions of the Northern Hemisphere to totl nnul mercury deposition in the Arctic from nthropogenic nd from nturl sources is shown in Figures 4.9() nd 4.9(), respectively for the upper (Scenrio I) nd lower (Scenrio II) limits of emission estimtes. Figure Men nnul ir concentrtions of PCB-153 over the Northern Hemisphere. The enlrged pnel shows the ir concentrtion pttern over the Arctic region. Figure Sesonl vrition in the reltive contriutions of different source regions to PCB-153 deposition in the Arctic. considerle uncertinty regrding the input prmeters used for the modeling of nturl emission nd re-emission processes, nd tht nturl emissions cnnot e controlled y politicl decisions, ttention should e focused on deposition from nthropogenic sources. The most significnt contriution to nthropogenic mercury deposition in the Arctic come from sources locted in Southest Asi, Europe nd Russi. The most significnt contriutions to the nturl component of nnul deposition in the Arctic re from the Pcific nd Atlntic Ocens, nd from Asi. Bering in mind tht there is still PCBs Levels of PCB contmintion re exemplified y PCB Figure 4.10 shows tht res with the highest ir concentrtions of PCB-153 re locted close to Europen nd North Americn source regions. Air concentrtions rnge from 5 to 20 pg/m 3 in contminted res of North Americ, nd cn exceed 20 pg/m 3 in Europe. Europen sources mke the lrgest contriution to the contmintion of the Arctic region. The men nnul ir concentrtion of PCB-153 over the Arctic rnges from 0.2 to 4 pg/m 3. Figure Air concentrtions of PCB-153 emitted in Jnury nd My from sources in the Americs nd Northwest Europe. respectively, from modelling results for Americs Jnury Northwest Europe c Americs My Northwest Europe d 40

9 Chpter Assessment of distnt sources: Long-rnge tmospheric trnsport The reltive contriutions mde y different source regions to PCB-153 deposition in the Arctic re suject to sesonl vritions, s shown in Figure The contriution from sources in Northwest Europe is the most vrile, vrying from out 70% in Jnury, to out 25% in My. The mount contriuted y the Americs is only out 5% in Jnury, ut in My it mounts to 26%, nd is comprle with the contriution from sources in Northwest Europe. These noticele vritions re explined y the peculirities of tmospheric circultion in the Arctic during vrious sesons, nd lso y sesonl vritions in temperture, precipittion, nd degrdtion rtes. Sesonl vrition of emissions re not tken into ccount in this ssessment. To illustrte pthwys of tmospheric trnsport, simultion results of PCB-153 trnsport from two source regions (the Americs nd Northwest Europe) for 1996 were exmined. Figures show ir concentrtions of PCB-153 emitted in the Americs nd Northwestern Europe in Jnury. The ir concentrtions of PCB- 153 originting from the sme sources in My re given in Figures Figure 4.13 shows the contriution of different source regions to PCB-153 deposition in the Arctic. The mjor contriution is from sources in Northwest Europe (out 40%). Other significnt contriutors re Russi (19%), the Americs (17%) nd Southest Europe (16%). For PCB-28 nd PCB-118, Northwest Europe nd Russi re the min contriutors. However, for PCB-180, min contriutors re Northwest Europe nd the Americs. The totl mount of PCB-153 deposited in the Arctic region from emissions in 1996 ws estimted t 527 kg. The contriution from re-emission of PCB- 153 ccumulted in the environment in the period Figure γ-hch concentrtions in ir of the lower tmosphere over the Northern Hemisphere nd the Arctic. preceding 1996 equls 629 kg. Therefore, the estimted totl PCB-153 deposition to the Arctic in 1996 ws 1.15 tonnes. On the sis of the trnsport simultions for the four congeners (PCB-28, -118, -153, nd -180), nd tking into ccount the frctions of these congeners in the typicl PCB mixture in ir, rough estimte of totl PCB deposition in the Arctic in 1996 of pproximtely 40 tonnes ws mde. γ-hch Figure 4.14 represents the sptil distriution of γ- HCH concentrtions in the ir over the Northern Hemisphere nd the Arctic. High concentrtions (up to 5 ng/m 3 or more) re minly chrcteristic of regions with high emissions. However, in spite of the fct tht there re no significnt sources in the Arctic region, reltively high concentrtions (from 0.01 to 0.11 ng/m 3 ) re lso oserved there. These concentrtions result from long-rnge trnsport of γ-hch from remote sources, minly in Western Europe, Indi, nd the Americs. Figure Contriutions of different source regions to PCB-153 deposition in the Arctic region in Figure Men nnul concentrtions of γ-hch in sewter in the Northern Hemisphere. The enlrged pnel shows the sewter concentrtions pttern over the Arctic Ocen. 41

10 4.2. Assessment of distnt sources: Long-rnge tmospheric trnsport Chpter 4 Since γ-hch tends to ccumulte in sewter (which ccounts for out 80% of the overll environmentl pool of this sustnce), the sptil distriution of γ- HCH in sewter is of interest. The distriution of γ- HCH in sewter (Figure 4.15) revels tht mximum concentrtions re found in the Indin Ocen, the Mediterrnen Se, nd the Est Atlntic. Considerle mounts of γ-hch flow into the Arctic Ocen from the North Atlntic, s reflected in the higher sewter concentrtions in the Brents Se in the region etween northern Norwy nd Svlrd. Sewter concentrtions in the ses long the cost of northern Russin re in the rnge ng/l. The totl mount of γ-hch deposited in the Arctic region in 1996 from the tmosphere ws estimted to e 78 tonnes. Due to high deposition rtes over the se (the models ssume this rte to e twice s high over se s on lnd), nd tking into ccount the lrge proportion of the Arctic re tht is covered y ocen (out 60%, ccording to figures provided y AMAP, 1998), this equtes to n estimte for γ-hch deposited to the Arctic Ocen in 1996 of 58 tonnes. Modeling results hve een used to indicte contriutions of different emission sources to the contmintion of the Arctic region y γ-hch (Figure 4.16). Western Europe is the lrgest contriutor to this region (out 40%), followed y Indi (19%), the Americs (17%), Chin (10%), nd Russi (6%), with other source regions responsile for the remining 8%. Figure Sptil distriution of men nnul ir concentrtions of totl gseous mercury in the Russin North. regions including the Ymlo-Nenets AO, the Repulic of Skh (Ykuti), nd the Chukchi AO. A possile reson for this, in ddition to distnce from min emissions res, is the decrese in elementl mercury concentrtion over the Arctic cost during springtime, s result of MDEs. Tle 4.3. Chrcteristic vlues of mercury ir concentrtions in the Russin North, ng/m 3. The sptil distriution of nnul deposition lods of totl mercury in the Russin North is shown in Figure The highest depositions, exceeding 20 g/km 2 /y, re oserved over the cost of the Arctic Ocen, due to MDEs (Tle 4.4). The lowest depositions (less thn 5 g/km 2 /y), re in Centrl Ykuti, n re of low nnul precipittion. Vlues of totl mercury deposition for regions of the Russin North nd the Arctic s whole re given in Tle 4.5. Figure Contriutions of different source regions to γ-hch deposition in the Arctic in Contmintion levels nd deposition lods resulting from long-rnge tmospheric trnsport to the Russin North Mercury Figure 4.17 shows the modeled sptil distriution of men nnul concentrtions of totl gseous mercury (TGM) in the ir in northern Russi, which re firly constnt cross the territory (from 1.4 to 1.8 ng/m 3 ) (see lso Tle 4.3). Concentrtion levels over Murmnsk Olst nd in the centrl Repulic of Skh (Ykuti) re slightly elevted, minly due to locl emission sources. There is lso wek decresing grdient in mercury concentrtions to the north over Figure Annul deposition of totl mercury in the Russin North. Tle 4.4. Chrcteristic vlues of totl nnul mercury deposition lods in the Russin North, g/km 2 /y. 42

11 Chpter Assessment of distnt sources: Long-rnge tmospheric trnsport Tle 4.5. Totl deposition of mercury in 1996 in different regions of the Russin North, nd the Arctic s whole, t/y. PCBs Figures 4.19 nd 4.20 show the sptil distriutions of men nnul ir concentrtions nd nnul deposition lods of PCB-153 over selected regions of the Russin North for There is cler decrese in PCB-153 ir concentrtions from western to estern res of the Russin North, with incresing distnce from source res in Europe. Reltively high ir concentrtions (up to 4 pg/m 3 ) occur in Murmnsk Olst, the Nenets AO, nd the southern prt of the Ymlo-Nenets nd Tymir AOs (Tle 4.6). Moderte vlues (1 2 pg/m 3 ) re chrcteristic of the northern prt of the Ymlo- Nenets AO, the Tymir AO, nd the Repulic of Skh (Ykuti). The Chukchi AO is chrcterized y low vlues (<1 pg/m 3 ). A similr pttern is seen for deposition lods. Sustntil vlues (>150 mg/km 2 /y) re estimted for Murmnsk Olst, the Nenets AO nd the southern prt of the Ymlo-Nenets nd Tymir AOs s well s for the western prt of the Skh Repulic. Moderte vlues ( mg/km 2 /y) re otined for the northern prt of the Ymlo-Nenets nd Tymir AOs, the Repulic of Skh (Ykuti), nd the western prt of Chukchi AO. The northern prts of the Russin North re chrcterized y lower vlues for deposition lods (<70 mg/km 2 /y) (Tle 4.7). Tle 4.7. Chrcteristic vlues of PCB-153 nnul deposition lods in the Russin North, mg/km 2 /y. Depositions of PCB-153 nd of totl PCBs to the Russin North nd the Arctic re given in Tle 4.8. To clculte these depositions, emissions of the 22 PCB congeners considered, from ll source regions, were divided into four groups: di- plus tri-chlorinted PCBs, tetr- plus pent-chlorinted PCBs, hexchlorinted PCBs, nd hept- plus oct-chlorinted PCBs. It ws ssumed tht these groups re trnsported in similr wy to PCB-28, -118, -153 nd -180, respectively. Together, these 22 congeners represent out one hlf of totl PCB emissions, fct tht ws tken into ccount in the clcultion. Figure Sptil distriution of men nnul ir concentrtions of PCB-153 in the Russin North, clculted for Tle 4.6. Chrcteristic vlues of PCB-153 ir concentrtions in the Russin North, pg/m 3. Tle 4.8. Totl deposition of PCB-153 nd totl PCB in 1996 in different regions of the Russin North, nd the Arctic s whole, t/y. By undertking simultions of long-rnge trnsport nd the ccumultion of four PCB congeners (PCB-28, -118, -153 nd -180), it ws possile to compre the congener compositions in the ir of different regions of the Russin North (Figure 4.21). Figure PCB congener composition in ir of different regions of the Russin North. Figure Annul deposition of PCB-153 in the Russin North, clculted for For ll receptor regions, the frction of PCB-28 is the highest nd PCB-180 the lowest, with other congeners flling etween, however, the congener ptterns vry noticely etween the regions. 43

12 4.2. Assessment of distnt sources: Long-rnge tmospheric trnsport Chpter 4 γ-hch Men nnul ir concentrtions of γ-hch in the receptor regions of the Russin North, for 1996, re illustrted in Figure Higher ir concentrtion levels (from 0.02 to 0.07 ng/m 3 ) re chrcteristic for Murmnsk Olst, the Nenets AO, the south of the Ymlo-Nenets AO, nd the Repulic of Skh (Ykuti). Lower levels (from 0.01 to 0.3 ng/m 3 ) re chrcteristic for the Tymir AO, the Chukchi AO, nd the north of the Repulic of Skh (Ykuti) (Tle 4.9). lower for the Tymir AO, the Repulic of Skh (Ykuti), nd the Chukchi AO (0.1 3 g/km 2 /y). Annul deposition lods vry from region to region (Tle 4.10). This is minly due to different precipittion levels in these regions. Estimted vlues for totl deposition of γ-hch in the regions of the Russin North nd the Arctic s whole re given in Tle Tle Totl deposition of γ-hch in 1996 in different regions of the Russin North, nd the Arctic s whole, t/y Source-receptor reltionships for the selected pilot study regions. Figure Sptil distriution of men nnul ir concentrtions of γ-hch in the Russin North, clculted for Tle 4.9. Chrcteristic vlues of γ-hch ir concentrtions in the Russin North, ng/m 3. The sptil distriution of γ-hch nnul deposition lods is shown in Figure Deposition lods re lrger for Murmnsk Olst, the Nenets AO, nd the Ymlo-Nenets AO (from 2 to 7 g/km 2 /y or more) nd Figure Annul deposition of γ-hch in the Russin North, clculted for Tle Chrcteristic vlues of γ-hch nnul deposition lods in the Russin North, g/km 2 /y Murmnsk Olst Mercury Murmnsk Olst is the most westerly region of Russi nd is locted on the Kol Peninsul. This explins the greter influence of Europen sources of mercury on this region (including sources oth inside nd outside the territories of Russi). Figures 4.24() nd 4.24() illustrte the contriutions of mjor Northern Hemispheric nd Russin nthropogenic mercury source regions to nnul mercury deposition in Murmnsk Olst. The lrgest contriution is mde y Russin sources (35%). Among these, out 13% is from Murmnsk Olst itself (MUR) nd 18% from other Russin Europen regions (NRT, NWK, CVV, CVN nd URL). The most importnt sources outside of Russi re those in Estern Europe (12%), Chin (11%), the Americs (10%), nd Western Europe (10%). The other ctegory (defined in this nd other sections ddressing mercury source-receptor reltionships) includes Northern nd Southern Europe, Southest Asi (excluding Chin nd Jpn), nd Afric, due to their reltively smll contriutions to depositions in the receptor re. PCB The lrgest contriutions to PCB-153 deposition in Murmnsk Olst re from emission sources in Russi (44%), Northwest Europe (35%) nd Southest Europe (14%) (Figure 4.25()). Contriutions from sources locted in the Americs, Afric, nd Centrl Asi re less significnt due to their considerle distnce from the Olst. Amongst Russin sources (Figure 4.25()), the mjor contriution is mde y emissions from Murmnsk Olst itself (22%). γ-hch γ-hch sources in Western Europe mke the lrgest contriution to deposition in Murmnsk Olst (more thn 50%). Other significnt contriutors re Russi (17 %) nd Indi (9%) (Figure 4.26()). 44

13 Chpter Assessment of distnt sources: Long-rnge tmospheric trnsport Figure Contriutions from nthropogenic sources in () regions of the Northern Hemisphere, () regions of Russi to nnul mercury deposition in Murmnsk Olst. Figure Contriutions from nthropogenic sources in () regions of the Northern Hemisphere, () regions of Russi to nnul PCB-153 deposition in Murmnsk Olst. Russin contriutions to γ-hch depositions in Murmnsk Olst re mostly mde y the Centrl nd Volgo-Vitsky regions (CVV) nd the Centrl- Chernozem, Volg, nd North-Cucsin regions (CVN), 5% nd 4%, respectively. The inputs from other regions re comprtively smll (Figure 4.26()). For the purposes of this report, contriutions from Russin emission sources to γ-hch depositions in receptor res re shown only for those regions with significnt emissions of γ-hch. Figure Contriutions from nthropogenic sources in () regions of the Northern Hemisphere, nd () regions of Russi to nnul γ-hch deposition in Murmnsk Olst The Nenets Autonomous Okrug Mercury The Nenets AO is locted in the northern prt of Europen Russi. Therefore the min source res of long-rnge tmosphericlly trnsported pollution ffecting the region re similr to those ffecting Murmnsk Olst. Differences in deposition re ssocited minly with the greter significnce of Russin emission source regions. Figures 4.27() nd 4.27() Figure Contriutions from nthropogenic sources in () regions of the Northern Hemisphere, () regions of Russi to nnul mercury deposition in the Nenets AO. 45

14 4.2. Assessment of distnt sources: Long-rnge tmospheric trnsport Chpter 4 show the reltive contriution of the different regions to the totl nnul deposition of mercury in the Nenets AO from nthropogenic sources. The lrgest contriution is from Russin sources (35%). However, sources within the Nenets AO itself only contriute 7%, wheres the comined contriution of regions in Europen Russi mke up 24% of the deposition. The most importnt of these re the Northern region (NRT) nd the Centrl nd Volgo-Vitsky regions (CVV). The most significnt externl contriutors re Estern Europe (13%), Chin (11%), the Americs (10%), Western Europe (9%), nd Centrl Asi (9%). PCB The lrgest contriutions to PCB-153 depositions re mde y Russi (41%), Northwest Europe (31%) nd Southest Europe (18%) (Figure 4.28()). The min contriutions mong Russin sources (Figure 4.28()) re mde y the Centrl nd Volgo-Vitsky regions (CVV) nd the Northern region (NRT), with vlues of 15% nd 10%, respectively. γ-hch The mjor contriutions to the contmintion of the Nenets AO y γ-hch re from emission sources in Western Europe (49%), Russi (23%), nd Indi (9%) (Figure 4.29()). The min sources within the Russin Federtion re the Centrl nd Volgo-Vitsky regions (CVV) nd the Centrl-Chernozem, Volg, nd North- Cucsin regions (CNV), contriuting 8% ech (Figure. 4.29()) The Ymlo-Nenets nd Tymir Autonomous Okrugs Mercury The loction of the Ymlo-Nenets AO nd the Tymir AO in the northern prt of western Sieri, ccounts for the fct tht Asin sources ply noticele role in their contmintion. Europen sources, however, still continue to exert considerle influence. Up to 30% of ll mercury nnully deposited in these two regions is from Russin sources (Figure 4.30()). The contriution from sources within the Ymlo-Nenets nd Figure Contriutions from nthropogenic sources in () regions of the Northern Hemisphere, () regions of Russi to nnul PCB-153 deposition in the Nenets AO. Figure Contriutions from nthropogenic sources in () regions of the Northern Hemisphere, () regions of Russi to nnul γ-hch deposition in the Nenets AO. Figure Contriutions from nthropogenic sources in () regions of the Northern Hemisphere, () regions of Russi to nnul mercury deposition in the Ymlo-Nenets AO nd the Tymir AO. 46

15 Chpter Assessment of distnt sources: Long-rnge tmospheric trnsport Figure Contriutions from nthropogenic sources in () regions of the Northern Hemisphere, () regions of Russi to nnul PCB-153 deposition in the Ymlo-Nenets AO nd the Tymir AO. Figure Contriutions from nthropogenic sources in () regions of the Northern Hemisphere, () regions of Russi to nnul γ-hch deposition in the Ymlo-Nenets AO nd the Tymir AO. Tymir AOs themselves is comprtively low (only out 3%), wheres three mjor Russin contriutors (CVV, CVN, nd URL) mke up 16% of totl deposition (Figure 4.30()). The two mjor externl contriutors re Chin (12%) nd Estern Europe (12%). Some impct is lso mde y the Americs (11%), Centrl Asi (11%) nd Western Europe (9%). PCB Mjor contriutions to PCB deposition in the Ymlo- Nenets nd Tymir AOs re mde y sources in Russi (47%), Northwest Europe (26%) nd Southest Europe (16%) (Figure 4.31()). Among Russin sources (Figure 4.31()), the lrgest contriution (12%) to depositions re mde y the Centrl nd Volgo-Vitsky regions CVV). The contriution of emission sources locted within the Ymlo-Nenets nd Tymir AOs is 9%. γ-hch Min contriutors to depositions of γ-hch in the Ymlo-Nenets nd Tymir AOs re similr to those for the Nenets AO. Sources in Western Europe mke the lrgest contriution to ongoing deposition in these territories (48%). Russi is responsile for 21% nd Indi, for Figure Contriutions from nthropogenic sources in () regions of the Northern Hemisphere, () regions of Russi to nnul mercury deposition in the Chukchi AO. 10% (Figure 4.32()). Russin contriutions to depositions in the Ymlo-Nenets nd Tymir AOs re minly from the Centrl nd Volg-Vitsky regions (CVV) nd the Centrl-Chernozem, Volg, nd North-Cucsin regions (CVN), 7% nd 8% respectively (Figure 4.32()) Chukchi Autonomous Okrug Mercury The Chukchi AO is the most estern nd remote region of the Russin North. Its loction, fr from mjor industril regions, ccounts for the fct tht the glol ckground pool of tmospheric mercury is the min source of mercury contmintion in this region. Figure 4.33() demonstrtes the reltive contriutions of different source regions to nnul mercury deposition in the Chukchi AO. The min contriutor is Russi (26%), however, contriutions from Chin re lso considerle (17%). Among other sources, the Americs (11%), Centrl Asi (10%), nd Estern Europe (10%) re of note. The contriution from the Chukotk AO itself is insignificnt compred to emission sources locted in Estern Sieri nd the Fr Est (Figure 4.33()). However, the influence of mjor emission regions in Europen Russi (CVV, CVN, URL) re lso pprent. 47

16 4.2. Assessment of distnt sources: Long-rnge tmospheric trnsport Chpter 4 Figure Contriutions from nthropogenic sources in () regions of the Northern Hemisphere, () regions of Russi to nnul PCB-153 deposition in the Chukchi AO. PCB The most importnt contriutions to PCB-153 deposition in the Chukchi AO re mde y sources locted in Russi (25%), Northwest Europe (22%), nd Southest Europe (19%), followed y Americn sources (17%). (Figure 4.34()). The min contriution from the Russin source regions (Figure 4.34()) is mde y emissions from the Chukchi AO itself (8%). γ-hch For the Chukchi AO, the min contriutions to γ-hch contmintion re mde y Indi (27%), Western Europe (27%), Chin (19%), nd the Americs (11%) (Figure 4.35()). The contriution from ll Russin sources ccounts for only 5% (Figure 4.35()) Conclusions Murmnsk Olst The lrgest contriution to nthropogenic mercury deposition in the Olst is mde y Russin sources (35%) of which 13% is from sources within Murmnsk Olst itself. The most importnt externl sources re Estern Europe (12%), Chin (11%), the Americs (10%), nd Western Europe (10%). Totl nnul deposition of mercury is round 3 t, including 1.5 t from nthropogenic sources. A mjor contriution to PCB deposition is mde y Russin sources (44%) including 22% from sources within Murmnsk Olst itself. Among other emission sources, significnt contriutions originte in Northwest Europe (35%), nd Southest Europe (14%). Totl nnul deposition of PCB-153 in Murmnsk Olst mounts to 20 kg, nd of totl PCBs, 0.7 t. Figure Contriutions from nthropogenic sources in () regions of the Northern Hemisphere, () regions of Russi to nnul γ-hch deposition in the Chukchi AO. Min contriutions to γ-hch deposition re mde y sources within Western Europe (54%), Russi (17%), nd Indi (9%). Russin contriutions to deposition re minly from sources locted in the Centrl nd Volgo-Vitsky regions (5%), nd Centrl-Chernozem, Volg, nd North-Cucsin regions (4%). Totl nnul deposition of γ -HCH mounts to 0.8 t. The Nenets Autonomous Okrug The most importnt contriution to nthropogenic mercury depositions in the Nenets AO is mde y Russin emission sources (35%). As well s deposition from sources within the Nenets AO itself (7%), emissions from regions in the Europen prt of Russi contriute considerly to the pollution of this region (24%). The most importnt externl contriutors re Estern Europe (13%), Chin (11%), nd the Americs (10%). Totl nnul deposition of mercury in the Nenets AO mounts to 4 t, of which 1.8 t is from nthropogenic sources. Min contriutions to PCB deposition in the Nenets AO re from sources in Russi (41%), Northwest Europe (31%), nd Southest Europe (18%). Mjor contriutions from sources within the Russin Federtion re mde y the Centrl nd Volgo-Vitsky regions (15%), nd the Northern region (10%). The contriution of locl sources to deposition in the Nenets AO is negligile. Totl nnul deposition of PCB-153 in this Okrug mounts to 31 kg, nd of totl PCBs, 1 t. γ-hch pollution of the Nenets AO is due to emission sources in Western Europe (49%), Russi (23%), nd Indi (9%). The min sources within the Russin Federtion re the Centrl nd Volgo-Vitsky regions 48

17 Chpter Preliminry ssessment of riverine fluxes s PTS sources (8%), nd the Centrl-Chernozem, Volg, nd North- Cucsin regions (8%). Totl nnul deposition of γ-hch to this Okrug is 1.1 t. The Ymlo-Nenets nd Tymir Autonomous Okrugs The mjor contriution to nthropogenic mercury deposition in these regions is from emissions sources in Russi (30%). Among Russin sources, the min contriutors re sources in the Url, Centrl nd Volgo-Vitsky regions, nd the Centrl-Chernozem, Volg, nd North-Cucsin regions (16% in totl). Min externl contriutors re Chin (12%), Estern Europe (12%), the Americs (11%), nd Centrl Asi (11%). Totl nnul deposition of mercury is estimted t 15 t, of which 6.6 t is from nthropogenic sources. Mjor contriutions to PCB depositions re mde y sources locted in Russi (47%), Northwest Europe (26%) nd Southest Europe (16%). Among Russin sources, the lrgest contriution to deposition is mde y the Centrl nd Volgo-Vitsky regions (12%). Totl nnul deposition of PCB-153 is 95 kg, nd 3.2 t for totl PCBs. Min contriutions to γ-hch depositions re mde y Western Europe (48%), Russi (21%), nd Indi (10%). Min sources within the Russin Federtion re the Centrl nd Volgo-Vitsky regions (7%) nd the Centrl-Chernozem, Volg, nd North-Cucsin regions (8%). Totl nnul deposition of γ-hch mounts to 4 t. The Chukchi Autonomous Okrug The min contriutions to nthropogenic mercury deposition in this Okrug originte from Russin sources (26%). Emission sources from Estern Sieri nd the Fr Est re the dominnt influences on mercury contmintion of the Chukchi AO. The min externl contriutor to the region s pollution is Chin (17%), with contriution comprle to tht of Russin sources, lthough this vries slightly during the yer. Among others, the Americs contriute 11% nd Centrl Asi 10% to the deposition. Totl nnul deposition of mercury is estimted t 7 t, of which 2.9 t is from nthropogenic sources. The min contriutors to PCB deposition re the following: Russi (25%), Northwest Europe (22%), nd Southest Europe (19%), followed y Americn sources (17%). The Chukchi AO itself contriutes 8%. The totl nnul deposition of PCB-153 mounts to 11.8 kg, nd of totl PCBs, 0.4 t. Min contriutions to γ-hch deposition re mde y Indi (27%), Western Europe (27%), Chin (19%), nd the Americs (11%). The contriution from Russin sources ccounts for 5%. Totl nnul deposition of γ-hch in the Chukchi AO is estimted t 1.4 t. In ddition, the following generl conclusions cn e mde, sed on the studies undertken: Europe, North Americ, nd Southest Asi re the most significnt emission source regions for mercury, PCBs nd γ-hch. The min Russin emission sources re locted in the Europen prt of the Russin Federtion. Due to their geogrphicl loction, nd to meteorologicl conditions, Europen sources mke the gretest contriution to the contmintion of the western regions of the Russin North. Asin nd North Americn sources ply more significnt role in the pollution of the estern territories of the Russin Arctic, lthough the contriution of Europen sources is still considerle. The results otined mke it possile to mke some predictions for the ner future regrding contmintion levels in the Russin Arctic. An nlysis of emission dt shows tht mercury emissions re decresing in Europe nd North Americ, wheres emissions from Southest Asi re incresing. Asin sources my eventully ecome the more significnt, thus contmintion levels of this pollutnt in some regions of the Russin North, in prticulr the Chukchi AO, my increse in the future. Regrding γ-hch, use of technicl-hch ( mixture of HCH isomers, including γ-hch) is now nned in most western countries, nd in Russi since the lte- 1980s; Chin, mjor user, lso switched to lindne (pure γ-hch) in Although restricted in most countries, lindne is still widely used in North Americ, Europe nd Asi, for seed tretment nd other pplictions (AMAP, 2002). Thus the reltive influence of Asin countries on pollution of the Russin Arctic y γ-hch is likely to increse. PCB contmintion levels re expected to decrese with emission reductions resulting from ns nd controls on use of PCBs. However PCB contmintion is likely to continue for mny yers s result of reemissions from PCBs ccumulted in the generl environment over the lst 50-yers Preliminry ssessment of riverine fluxes s PTS sources Introduction Flows of lrge Arctic rivers re considered one of the most significnt pthwys y which contminnts rech the Arctic. Riverine trnsport is prticulrly relevnt for PTS, s potentilly PTS contmintion within the entire ctchment res of these rivers cn e trnsported to the Arctic through wtershed runoff, nd these ctchments include hevily industrilized res nd griculturl regions (Figure 4.36). Riverine PTS trnsport is prticulrly importnt for two of the study res selected for project implementtion: the lower Pechor sin, nd the estern prt of the Tymir Peninsul, in the re of the Yenisey river. 49