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Turkish J.Mar.Sci. I. (213) : 81 -9A(l995)

CHEMICAL PROPERTiES OF THE TWO-LAYER FLOW REGiMES

IN THE TURKISH STRAITS

TURK BOGAZLARJNDAJd j}(j TABAKALI AKJ REJjMjMN idMYASAL 0ZELUKLEID

SOLEYMAN TUGRUL, <;:OLPAN POLAT, OZDEN BA$T0R.K, EM.tN HATiPOGLU,

A Y$EN YlLMAZ, SEMAL YEMENtCiOGLU, CEMAL SA YDAM AND ILKA Y SALlliOGLU

Middle East Technical University, Institute of Marine Sciences, P.K. 28, Erdemli 33731, lye!, Turkey

Key Words : Bosphoms, Dardanelles, phosphoms compounds, nitrogen compounds

Abstract

Systematic data obtained at the exits of the Bosphoms and Dardanelles straits between 1986 and 1994 permit us to understand the seasonal variations in the nutrient properties of the counter flows in the Turkish Straits. The brackish outflow from the Black Sea enters the Marmara Sea with low levels of inorganic nutrients (P04-P <0.1 ~tM; N03+N02-N <0.1-0.2 ~tM) from spring to autumn but possesses unexpectedly high concentrations (P04-P=0.3-0.4 ltM; N03+N02-N=S-? ~tM) in early winter. The calcula!ed annual average concentrations of P04 and N03+N02 are about 0.11 and 1.3 ~tM, respectively. However, the nutrient properties of the brackish waters of Black Sea origin are modified noticeably as they flow through the Marmara basin and the Dardanell~ .potb by biomediated chemical processes and by the ex-port of biogenic organic particles to the lower layer. The salty Mediterranean inflow to the Marmara deep basin via the Dardanelles Strait contains low nutrient concentrations (N03+NOrN=l.O ~tM; P04-P=0.05 ~tM, on average). However, the salty water, before reaching the Black Sea via the Bosphoms, is much enriched with inorganic nutrients in the Marmara basin by the input from the surface flow; the average concentrations being as high as 9.6 ~tM for N03+NOr N and 1.0 ~tM for P04. In other words, the initially nutrient-poor Mediterranean water spreads into the Black Sea with its nitrate+nitrite and phosphate concentrations enriched at least 10-20 fold, which are larger than the biologically labile nutrient content of the Black Sea outflow.

81

..: ,. ...

Introduction

The Black Sea. an inland sea principally fed by fresh. riverine waters. is connected to the Mediterranean through the so-called Turkish Strai ts System (TSS) comprising the Sea of Marmara. the Dardanelles and the Bosphoms Straits (Figure I). Accordingly. the counter flows in the TSS permit the wat.cr exchanges between the Mcditerranc<lll and the Black Sea throughout the year (Gunnerson and Ot.turgut. 197-l: Sorokin, 1983: Bc~iktcpc et nl .. 1993: OguL and Rozman. 1991). resulting in the formation of distinctly different two-layer ecosystems in both the Marmara and Black Seas (Sorokin. 1983: Ba~llirk et a! .. 1990: T ugnil . 1993: Polat and Tugrul. 1995: Polat 1995).

During recent decades the chemical properties of the exchange flows in the TSS have been modified by large discharges of land-based chemicals to the adjacent seas (Mee. 1992: Orhon et nl.. 199-t: Tugrul and Polat. in press). In particular. heavily polluted riverine discharges to the western Black Sea have dramatically modified the biochemical properties of the northwestern shelf waters (Baloga 1985: Mcc, 1992) flowing toward the Bosphoms region through alongshore currents (Sur et a/.. 1994 ). T he Black Sea outflow is further contaminated by the waste discharged from the city of Istanbul into the Bosphoms surface current toward the Marmara Sea and by the natural input of vertical mixing from the Mannara lower layer (Orhon et nl . . 199-+: Ba~tlirk et nl.. 1990: Pol at and Tugml. 1995). In the Marmara basin. the biogeochemical properties of the Black Sea outflow arc modified by biorncdiatcd chemical processes. before reaching as far as the Aegean Sea (Ba~tiirk et a/ .. 1990: Polat. 1995).

On the other hand. the salty. oxygen saturated waters of the Aegean Sea are well known to contain low concentrations of inorganic nutrients (Ba~tiirk et nl.. 1990). In the Marmara basin. the salty Mediterranean water becomes marked!) enriched with ino rganic nutrients due to biogenic particle snow from the surface to the Marmara lower layer (Ba~tiirk et a/ .. 1990).

Systematic nutrient data from the T urkish Straits arc of critical importance for establishing chemical balances both in the Sea of Marmara and in the Aegean Sea. though the Bosphoms fluxes arc expected to make an insignificant contribution to the whole Black Sea ecosystem (Fonsclius. 197-l). These data are also essential for ecosystem and water quality models. as well as for the improved understanding of the long-term changes in the chemical oceanography of the TSS. With these goals. a na tional oceanographic monitoring and research programme has been conducted si nce 1986 throughout the TSS by the Institute of Marine Sciences of the Middle East Technical University (IMS-tv!ETU).

In the present paper. recent systematic data arc discussed so as to characterize the hydrochemica l properties of the Aegean and the Black Sea waters excha ng ing via the TSS.

l\latcrials And Methods

Water samples were collected during the 1986- 1994 cmises of RN Bilim either with conventional Nanscn bottles or a 12-bottlc Rozelle a ttached to a Sea-Bird Model CTD probe system. Phosphate and nitrate samples were kept frot.cn until processed by a two-

82

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channel Technicon Model Ali auto-analyzer. The conventional colorimetric methods followed were very similar to those given in Strickland and Parsons ( 1972).

Results lind Discussion

Vertical Profiles: T he typical salinity and nutrient profiles displayed in Figures 2 and 3 enable one to deduce the boundaries of the surface and counter nows at both exits of the Bosphoms and Dardanelles. As shown in Figure 2a, at the northern entrance of t11c Bosphorus Strait, the brackish, 17-18 ppt salinity, waters of the Black Sea occupy the upper layer down to 45-50 m throughout the year. below which a counterflow introduces diluted Mediterranean waters from the Marntara basin to the Black Sea. The Bosphorus surface now becomes as thin as I 0-15 m at the southern exit but more saline by at least 2-3 ppt before spreading into the Mannara basin. The Black Sea outflow via the Bosphon1s increases during spring and early summer and decreases during autumn and winter (Unlliata et a/., 1990; Latif eta/ .. 1991: Ogu z and Sur. 1989; Latif eta/ .. 1992: Ozso) et nl.. 1992: Be~iktepe eta/ .. 1994: Ozsoy eta/ .. 1994).

The typical chemical profiles in Figure 2a demonstrate that the Black Sea waters enter the Bosphoms Strait with vcrticallj uniforn1 but seasonally varying concentrations of inorganic nutrients, namely reactive phosphate (P04-P) and nitrate (in fact nitratc+nitritc). At the northe rn exit of the s trait the nutrient concentrations of the diluted Mediterranean waters increase with depth due to their mixing with t11c Black Sea waters having low nutrient for most of the year: however. in winte r when the Black Sea oulflow becomes enriched with nutrients by the land-based input and the decreasing assimilation by photosynthesis (Polat and Tug ml. 1995), nutrient profiles may become vcrticall} uniform in the entire water column. as is clearly seen in Figure 2a.

The sa lty wate rs of the Marmara Sea at U1c southern entrance of the s trait also possess vertically homogeneous distributions of nutrients (Figure 2b). Moreo\'er. the sal ty water is always enriched in phosphate and nitrate relative to the concentrations in the Bosphorus .mrfacc now. Since the Black Sea outnow generally contains low concentrations of nutrients, a steep nutriclinc is formed within the interface whose slope changes signilicanUy both with season and location in the strait.

The Marmara surface outnow a t the northe rn entrance of the Dardanelles Stra it has a vertically uniform salinity (isohalinc feature) down to 20 m in summer (Figure 3): in winter it becomes thicker and at least 2-4 ppt more saline due to intense mixing in the Marmara basin (Ogu z and Sur. 1989). The countcrflows in the strait arc separa ted by a sharp interface as in the Bosphoms Strait. The surface mixed layer becomes thinne r and more saline in the soutwestcrn entrance of the strai t where. dm\n to the lower haloclinc. the surface waters now toward the Aegean Sea (Polat. 1995). The Aegean outnow (S=39.0 ppt) is diluted insignificantly by vertical mixing in the Dardanelles when the Marmara basin is reached (Figure 3).

As can be reali t.cd from the typical profiles in Figure 3. the salt) Mediterranean wa ter enters the DCirdane lles Strait witlt onl} trace levels of both phosphate and nitra te concentrations: however, the vertically uniform concentrations of nitrate and phosphate

83

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have been observed to increase in \\inter (see Figure 3a) due to vertical mixing in the open sea. Similarly, the Dardanelles surface in1low to the Aegean Sea poscsses IO\\ concentrations of inorganic nutrients in April-September. displaying a homogeneous distribution with depth. During the same period. the entire water colum11 from the surface to the bottom has vertically unifonn chemical profiles due to the similarities between the nutrient concentrations of the upper and lower layer waters at the strait exit. The winter nitrate increases in the salty Aegean outflow result in the fom1ation of a seasonal nitraclinc coinciding with the permanent halocline (interface) at the exit (Figure 3a).

Sub-surface nitrate and phosphate maxima arc generally fonncd in the the water column of the northeastern exit (Figure 3b) for most of the year. Such distinguished features with seasonally varying peak values are the result of intmsion of the nutrient-poor, denser Mediterranean waters below the nutrient-enriched, older Mediterranean water existing in the lower layer of the Marmara-Dardanelles Junction (MDJ). However. when the salt) inflow from the Aegean Sea is strong enough to occupy the entire lower layer of the strait, the subhalocline waters in the DMJ region possess vertically uniform nutrient profiles as do the salty waters of the southern exit.

Seasonal Variations: The well-defined boundaries or the exchange nows in the strait entrances (Polat and Tugml. 1995: Polat. 1995) permit us to determine the layer-averaged nutrient concentrations for the exchanging waters of the adjacent seas through the Turkish Straits. Figttre 4a demonstrates the seasonal variation of inorganic nutrients in the Black Sea outllO\\ via the Bosphoms. The concentrations have been observed to increase markedly from summer to'' tnter: for instance. the nitrate values are always in the range of <0.1-0.2 ~LM in summer. reaching peak values of 4.5-7.5 ~LM in winter months. The winter Increases appear consistently in late November-December when the assimilation of nutrients by photosynthests tends to decrease to a minimum in the \Vestem Black Sea surface layer. Similar winter increases have also been reported for the northwestern coastal margin of the Black Sea (Bologa eta/.. 1981). indicating that in winter. a significant fraction of land-based nutrients introduced to the northwestern Black Sea may have reached as far as the Bosphorus by alongshore currents. Phosphate concentrations of the outflowdisplay a similar seasonalit} : the summer values arc always less than 0.1 ~LM \\-hcreas the \\inter concentrations may range between 0.3 and 0.4 ~LM (Figure -1-a) . In the late winter. whereas nitrate concentrations remain at peak levels. phosphate concentrations may tend to decrease due either to luxury consumption by photosynthesis or to sedimentation by adsorption onto particles in the coastal margins before reaching the Bosphoms. During the early spring bloom, the brackish water enters the Bosphoms with low inorganic nutrient concentrations but with large concentrations of particulate organic nutrients (Polat and Tugml. 1995: Polat. 1995).

The seasonality in the nutrient content of the Marmara surface outnow via the Dardanelles (Figure 5a) is much less pronounced than those in the Black Sea water entering the Marmara Sea via the Bosphoms (Figure 4a). The Marmara surface outflow is unpoverishcd in nitrate and phosphate after the spring bloom. yielding typical summer values of <0.05-0.1 ~LM for nitrate and <0.1 ~LM for phosphate. The winter concentrations for the Mannara surface outflo\\. as high as 1.0-1.3 ~tM for nitrate and 0.2-0.3 ~M for phosphate (Figure 5a). arc therefore consistently less than the peak values recorded in the

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Black Sea outflow (sec Figure 4a). These winter maxima arc the result of entrainment of the inorganic nutrient-enriched salty waters from the lower layer to the surface layer by intense vertical mixing because large winter input by the Bosphoms surface inflow is consumed by biomcdiatcd chemical processes in the eastern Marmara and the majority of the nutrient-associated organic particles sink out of the surface layer before Dardanelles is reached (Ba~ttirk eta/ .. 1990: Po lat. 1995). ·

Comparison of the nutrient contents of the Mediterranean waters flowing in the Dardanelles and the Bosphorus entrances (Figures 4b and 5b) indicates important spatial and temporal changes in the chemical properties of the sally outflow from the Aegean Sea. The Mediterranean water in the Dardanclles-Acgean Junction (DAJ) contains vel) low inorganic nutrient concentrations relative to its chemical properties in the Bosphoms region. Moreover, the concentrations in the DAJ vary markedly with season. increasing consistently from summer to winter (sec Figure 5b). However, the seasonality is much more pronounced in the nitrate concentrations. varying from <0.1 J!M in summer to 2 .0-2.4 ~LM in "~ntcr, whereas the phosphate concentration ranges seasonally between <0.02 (detection limit of the method) and 0.06-0.08 J!M. The consistent \\inter increases in the nutrient content of the salty water in the DAJ is principally the result of the input from the deep layers by convective winter mixing in the open Aegean Sea (Kiic;:tiksct.gin et a/., u1

press). rather than tl1e input from land-based sources. Particulate nutncnt data obtamed in the strait between 1991-1994. Polat (1995), are comparable witl1 the inorganic nutrient concentrations of the Mediterranean water. The PON ranged seasonally between 0.04 and 0.70 ~LM. reaching peak values during the spring bloom though these arc less than the "inter nitrate concentrations. The particulate phosphoms (PP) concentrations were in the range of 0.01-0.35 ~1M: the PP maxima much exceed the phosphate maxima observed in winter (Polat. 1995).

The salty Mediterranean waters. poor in nutrients before they enter the Marmara Sea. become enriched at leal 10 fold with inorganic nutrients during their 6-7 years in the Marmara basin (DnJiiata et a/., 1990: Ba~tiirk et a/ . . 1990: Pol at. 1995). Accordingly. the Mediterranean water leaves the Marmara lower layer \\ith seasonally varying concentrations of 0. 7-1.3 ~LM for phosphate and 7-12 ~LM for nitrate as is clcarl) shown 111

Figure -lb. Since algal productiOn in the Marmara Sea is ltmited to the upper layer. the inorganic nutrient content of the sally Marmara outflow via the Bosphoms is much larger than the concentrations of particulate nutrients which arc of the order of 0.2-l.O ~LM for PON and 0 .03-0.07 ~LM for PP as discussed extensively b) Polat ( 1995) and b) Polat and Tugml ( 1995).

Annual Means of the Nutrient Concentrations: The annual means of the inorgantc and particulate nutrients in the c:xchange flows of the Turkish Straits have been estimated from the long-term data evaluated above as well as those given in Polat ( 1995) and Polat and Tugml ( 1995). Though data is \Cry scarce. the annual mean of ammonia (NH4 +) is less than the nitrate contents of the c:xchangc flows: tt is of the order of 0.05-0.1 ~LM for the salty Mcditcrancan waters both in the Dardanelles and in the Bosphonts region. whereas the Black Sea inflow probabl) contains 0.5 ~LM of NH4 + (Polat and Tugml. 1995) dropping to a lcYel of 0. 1-0.2 ~·M when the surface flo\\ reaches as far as the Dardanelles. The brackish outflow from the Black Sea possesses comparable annual concentrations of

85

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inorganic and particulate nutrients even though the concentrations reach peak values in different seasons: the estimated annual mean concentrations of nitrate and PON arc 1.3 and l. 96 ILM . respectively. The annual mean concentration of nitrate in the Marmara surface outflow via the Dardanelles drops to 0.33 ~LM whereas its PON concentration remains almost constant ( 1.94 ILM) from the Bosphorus to the Dardanelles exit.

The salty Mediterranean water enters the Marmara basin with low annual inorganic and particulate nutrient concentrations: 0 .05 ILM for phosphate, <0.05 ~tM for PP whereas the annual nitrate and PON concentrations arc 1.0 and 0.3 ILM. respectively. The salty water reaches U1e Bosphorus region with relatively high annual concentrations of nitrate (9.6 ILM) and phosphate ( 1.0 ILM). which arc much larger than their particulate components: 0.4 ~tM for PON and 0.05 ~tM for PP. on an annual basis.

In the surface outflows both from the Black and Marmara seas. labile (inorganic and particulate) nutrients have been observed to vary significantly with season: however. the combined concentrations of inorganic+particulate organic nutrients change only by some 10% on a yearly time scale because seasonal decrease in the inorganic nutrient content of the surface waters is partly compensated by an increase in the particulate organic nutrients of biogenic origin. as also emphasized by (Po lat. 1995).

Comparison of U1e annual mean concentrations of chemicals occurring in the exchange nows in the Turkish Straits reveals that the labile nutrient concentrations of the salty waters nowing into the Black Sea are 2-3 times larger than those of the Black Sea inflow to the Mannara surface layer. However. an opposite trend appears in the ratios of the chemical contents of the countcrnows in the Dardanelles Strait. As a concluding remark. when the annual volume nuxcs in the straits are taken into account. biologically labile nutrients exported from the Black Sea arc compensated by the importation from the Marmara lower layer. whereas the chemical export from the Mediterranean is less than the annual load of nutrients inOowing from the Sea of Marmara via U1e Dardanelles.

86

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istanbul ve (anakkale Bogazlannda 1986 ve 1994 ylllan arasmda sistematik olarak toplanan veriler. iki tabakah akinlllann besin turo ozellikJerini ve bunlann mevsimsel degi~imlerini anlamamll.a olanak tamr. Karadenit. suyu, ilkbahar-sonbahar doneminde Marmara Denizi'ne anorganik besin elementlerini dii~iik seviyelerde ta~trken (PO.rP <0. 1 ~tM : N03+NOrN <0. 1-0.2 11M) erken-kt~ donemlerinde ,r.aman zaman yiiksek deri~imlere (PO.t-P=0.3-0A ~tM: N03+N02-N=5-7 11M) rastlamr. Bu suda hesaplanan y llltk ortalama degerler PO-t ve N01+N02 ic;:in Sirastyla 0.11 ve 1.3 JtM'dir. Karadeniz su~ u Marmara Denin boy unca ugradtgt biyokimyasal prosesler ve biyolojik kokenli partikiillerin alt sulara c;:okmesi sonucunda o;:elliklcri yemden ~ekillemni~ olarak (anakkale BogaiJna ula~tr. Ttulu Akdeni;: girdisi. (anakka1e Boga;:t kanah ile Marmara derin basenine dii~iik seviyelerde besin tuzu ta~tr (ortalama N03+N02-N=l.O 11M: PO.t­P=0.05 JtM). Ancak. Akdeniz koken1i bu su istanbul Bogazt kanah ile Karadenile u1a~madan. Marmara Denizi'nde list suyun etkisiyle anorganik besin elementlerince zenginle~ir ve ortalama dcri~imler N03+N02-N ic;:in 9.6 JtM. PO.t-P ic;:inse 1.0 JtM seviyelerine yiikselir. Dtger bir degi~le. ba~langtc;:ta besin clementlerince fakir olan Akdeni;: suyu 10-20 kct. t.enginle~mi~ olarak Karadeniz'e yaylltr ki bu degerler Karadeniz list su giridisindeki degerlerden de yiiksektir.

Acknowledgements

We grateful!) thank the SCICntists or IMS-METU and the captain ami the crews or RN Hllun for thctr contritmtwns to thts study which has been Uu·oughly supported by the Turkish Scientific and Technical Research Council (TlJHITAK) and U1e NATO Scientific AJTairs Division wtUtin the framework of the Science for Stability Programme.

References

Ba~tlirk. 0 .. Tugml S .. Yt1mat .. A.. Saydam. C. ( 1990) Health of the Turkish Straits: Chemical and environmental aspects of the Sea of Marmara. METU-Institute of Marine Sciences. Tech. Rep., 90(-t). Erdemli-ic;:el. Turkey. pp.69

Be~iktepe. S.T.. Ot.so~. E. and Onliiata. 0. (1991) Filling of the Marmara Sea by the Dardanelles lower layer inflow. /)eep ,)'en Research .t0(9): 1815-1838.

Be~iktcpe. S.T .. Sur. H.l.. Ozsoy. E .. Latif. M.A.. Og1tz. T. and Onlliata 0. (199-t) The circulation and the hydrography of the Marmara Sea. Pro?,ress in Oceanography. 1-t:285-33-t.

Bologa. AS .. Usurelu. M. and Frangopol. P.T. ( 1981) Planktonic primary productivity of the Romanian surface coastal waters (Black Sea) in 1979. Ocennolo}!.in .leta . .t(3):343-349.

Bologa. AS. (1985) Planktonic primal) productivity of the Black Sea: a review Thn/lnssia lli?,O.I!nvlcn. 21/22: 1-22.

Fonsclius, S. H. ( 1974) Phosphoms in the Black Sea. In: The Black Sea- Geology. ( 'flemi.ltl:\' and lliolop,y. Memoirc No.20. pp.144-150. The American Assoc. Petroleum Geologists.

92

' ' ... : '· .~ ..

Gunnerson. C.G and bzturgut, E. (1974) The Bosphorus. In: The Black Sea Geology. Chemistry and Biology. Memoire No.20. pp.99-113, The American Assoc. Petroluem Geologists. J Kti<;iiksezgin. F.. Balc1. A.. Konta~. A. and Altay, 0. Distribution of nutrients andy chlorophyU-a in the Aegean Sea. Oceanolof!_ica Acta (in press).

Latif. M.A.. bzsoy. E .. Oguz. T. and Onliiata. 0. (1991) Observation of Mediterranean inflow into the Black Sea. Deep-Sea Research. 38(2):711-725.

Latif. M.L.. b z.soy. E .. Salihoglu. i.. Gaines. A.F., Ba~tiirk. b .. Yllmaz. A. and Tugrul. S. ( 1992) Monitoring via direct measurements of tl1e modes of mixing and transport of wastewater discharges into the Bosphorus underflow. l'vfETU-Institute of Marine Sciences. Tech.Rep. pp.92-2 , 98.

Mee. L.D. ( 1992) The Black Sea in crisis: The need for concerted international action /lmbio 21(4): 278-286.

Oguz. T. and Sur. H. I. ( 1989) A two-layer model of water exchange through the Dardanelles Strait Oceanologica , !eta. 12:23-3 I .

Og11z. T. and Rozman. L. ( 1991) Characteristics of the Mediterranean underflow in the southwestern Black Sea continental shelf/slope region Oceanolo)!.ica Acta. 14: 43 3-445 .

Orhon. D .. Uslu. 0 .. Meri<;. S .. Salihoglu i. and Filibeli. A. (1994) Wastewater management for Istanbul: Basis for treatment and disposal Environmental Pollution. 84:167-178.

bzsoy. E .. Latif. M.A. Be~iktepe. S .. Ogu1.. T.. Salihoglu. i.. Gaines. A.F .. Tugml. S .. Ba~Hirk. b. and Snydam. C. ( 1992) Monitoring via direct measurements of the modes of mixing and transport of wastewater discharges into the Bosphoms underflow. Second Progress Report. Institute of Marine Sciences. Middle East Techni cal University. pp.3 10.

b;.soy. E .. Gaines. A. F .. Latif. M.A.. Tugrul S. and others. I 994. Monitoring via direct measurements of the modes of mixing and transport of wastewater discharges into the Bosphorus underflo\\ . Final Report. Vol.l-2. Institute of Marine Sciences. Middle East Technical University.

Polat. S.(:. and Tugrul. S. ( 1995) Nutrient and organic carbon exchanges between the Black and Marmara seas through the Bosphorus Strait Continental ,)'/w(f Research. 15(9): 1115-1132.

Po lat. S.(:. ( 1995) Nutrient and organic carbon budgets of the Sea of Marmara : A progressive effo11 on the biogeochemical cycles of carbon. nitrogen and phosphoms. Ph.D. Thesis. Institute of Marine Sciences. Middle East Technical University: pp.215

Sorokin. Yu. l. (1983) The Black Sea. ln: Ketchum. B. H. (Ed.). Estuaries and Enclosed Seas Ecosystem o.fthe IJ'orlt!. 253-291. Elsevier-Amsterdam.

Strickland. J.D.H. and Parsons. T .R. ( 1972) A practical lullldbook of seawater analysis. 2nd cd .. Ottowa. Fisheries Research Board.

93

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Sur. H.i.. Ozsoy, E. and Duliiata. D. (1994) Boundary current instabilities. upwelling. shelf mixing and eutrophication processes in the Black Sea Progress in Oceanography, 33:227-26-l.

Tugrul, S. (1993) Comparison of TOC concentrations by persulphate-UV and HTCO techniques in the Marmara and Black Seas, Marine Chemistry, 41 : 265-270.

Tugrul. S. and Polat, S.C. Quantitative comparison of the influxes of nutrients and organic carbon into the Sea of Marmara both from anthropogenic inputs and from the Black Sea Water .\'cience and Teclmolof!,Y (in press).

Dnliiata. D .. T. Oguz. M.A. Latif. E. 0/..soy, 1990: On the physical oceanography of the Turkish Straits. In: Pratt. J. (Ed.) The Physical Oceanography of the Straits. 25-60 NATO/ASI Series. Portrecht. Kluwer Academic Publishers.

Received 2-'.11.1995

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