The Mediterranean Sea

393 Pages·2005·14.633 MB·English

by  Lucien Laubier (auth.), Alain Saliot (eds.)

HdbEnvChemVol.5,PartK(2005):3–27
DOI10.1007/b107142
© Springer-VerlagBerlinHeidelberg2005
Publishedonline:20June2005
MediterraneanSeaandHumans:
ImprovingaConflictualPartnership
LucienLaubier
Centred’OcéanologiedeMarseille,RuedelaBatteriedesLions,13007Marseille,France
[email protected]
1 InternationalFramework . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 TheMediterraneanSeaanditsRegion . . . . . . . . . . . . . . . . . . . . 6
2.1 GeographicSetting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 HydrodynamicSystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.3 MarineBiodiversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3 HumanActivitiesandPressures . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1 DemographicTrendsandUrbanDevelopment . . . . . . . . . . . . . . . . 10
3.2 Tourism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.3 UrbanSewageOutfalls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.4 DischargesviaRivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.4.1 RiverPollutionLoads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.4.2 SedimentFluxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.5 AgriculturalRunoff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.6 LivingResources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.6.1 MarineFisheries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.6.2 Aquaculture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.6.3 EutrophicationandBiodiversityChanges . . . . . . . . . . . . . . . . . . . 20
3.7 IndustrialActivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.8 MaritimeTraffic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.9 Sea-bedandSubsoilExploitation . . . . . . . . . . . . . . . . . . . . . . . 24
3.10 RadioactivePollution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Abstract Intense human activities in regions surrounding enclosed and semi-enclosed
seas such as the Mediterraneanproduce, in the long range, a strong environmentalim-
pact. The Mediterranean Sea was selected as early as 1975 as one of the first regional
projectsoftheUnitedNationsEnvironmentProgram(UNEP).Severalpoliticalinitiatives,
suchastheBarcelonaConvention,havereinforcedtheimpactoftheUNEPregionalpro-
gram.TheMediterraneanSeabenefitsfromamildsub-tropicalclimate.Riverdischarges
andprecipitationdonotcompensateforthestrongevaporationrate.Biodiversityishigh
compared with other oceans. Human impacts and pressures come from demographic
trends, tourism, urbansewageoutfalls,allland-based pollutionsources, and discharges
viarivers,agriculturerunoff,andindustrialactivity.Theseinducemarineeutrophication
andbiodiversitylosses.Fisheriesandaquaculture,togetherwiththeimpactofmaritime
transport and offshore hydrocarbon exploitation, complete the picture. In recent years,
4 L.Laubier
globalchangesandatemperatureincreasehaveaddedanunexpected impactoncoastal
ecosystems.
Keywords Anthropogenicpressure·Demography·Economicdevelopment·
MediterraneanSea·Pollutionsources
1
InternationalFramework
The use of the oceans as waste space for human discards has been accepted
throughout history. Only recently has such use been questioned because of
possible loss of, or restricted use of, marine resources, in particular living
resources.Asearlyasthe1960s,severalissueslinkedtomarinepollutionoc-
curredinthenorth-westernMediterraneanbasin,suchasthetitaniumoxide
wastesdischargedbetweentheItaliancoastandCorsicabyMontedisonorthe
dumpingofmineralsludgesresultingfrombauxiteprocessinginasubmarine
canyonsouth-eastofMarseilles.
Nevertheless, general public awareness of pollution problems was raised
by the first United Nations Conference on Environment held in Stockholm
in 1972, which gave birth to the United Nations Environment Program
(UNEP).Themainrecommendationsoftheconferencearewellknown:“Hu-
mans should protect and improve the environment of present and future
generations, and safeguard the natural resources thanks to good manage-
ment.” As far as the oceans are concerned, the conference recommended
that “states should take all possible actions to prevent pollution of the
seas.”
One year later, in June 1973, the UNEP decided to elaborate a continu-
ous monitoring program on pollution of the seas and its impact on marine
ecosystems, paying particular attention to the specific problems of certain
water bodies, such as semi-enclosed seas. On these lines, 16 Mediterranean
riverine countries (out of a total of 18) decided that the degradation of the
marine environment was a problem calling for global action at both na-
tional and regional levels. In 1975, the Mediterranean Action Plan (MAP),
in the framework of the UNEP regional seas program, was adopted. The
plan includes three different parts: a socio-economic one (known as Blue
Plan), a scientific one (known as MED POL) and a legal one (leading to the
BarcelonaConvention,seebelow).
The initial focus of MAP was on marine pollution monitoring and con-
trol.However,itiscurrentlyrecognizedthatpoormanagementandplanning
of development are at the origin of most environmental problems; hence
environmental protection is directly linked with social and economic de-
velopment. Although initially focusing on sea pollution abatement, MAP
also contributed to Integrated Coastal Zone Management through a special
MediterraneanSeaandHumans:ImprovingaConflictualPartnership 5
Coastal Area Management Program (CAMP), which has been oriented to-
wardspracticalcoastalmanagementprojectsinselectedcountries.
Parallel to MAP, the International Commission for Scientific Exploration
of the Mediterranean Sea decided to set up special scientific meetings on
Mediterranean Sea pollution during its biennial General Assemblies, called
PollutionDays.
The Barcelona Convention for the Protection of the Mediterranean Sea
Against Pollution was signed one year later, in 1976, by the same 16 coun-
tries.Twoprotocolsofactionwerealsoadopted:thefirstprotocoldealswith
the prevention of pollution by dumping operations from ships and aircraft
(Dumping Protocol)andthesecondonewithpollutionbyhydrocarbonsand
other noxious chemicals (Protocol Concerning Cooperation in Combating
Pollution of the Mediterranean Sea by Oil and other Harmful Substances in
Cases of Emergency). Other related protocols were later on adopted: a pro-
tocolagainstland-based pollutionin1980(ProtocolfortheProtectionofthe
Mediterranean Sea against Pollution from Land-Based Sources); a protocol
onSpecially ProtectedAreasofMediterranean Importance(SPAMI) in1982;
aprotocolagainstpollutionoftheseafloorandsubsoilresultingfromconti-
nentalshelfexplorationandexploitationin1994;aprotocolonthePrevention
ofPollutionoftheMediterraneanSeabyTransboundaryMovementsofHaz-
ardousWastesandtheirDisposalin1996[1].
More recently, the second United Nations Environment Conference held
in Rio de Janeiroin 1992 adopted, inter alia, several global conceptssuch as
sustainabledevelopmentandtheprecautionaryapproachprinciple.
In 1995, the European Union launched an important program for devel-
opment of Mediterranean third-world countries, called MEDA. At this oc-
casion, the European Union member states and the European Commission
decided to join the Barcelona Convention, which was revised accordingly
and renewed. A Euro-Mediterranean partnership was established with the
aim of guaranteeing peace, stability, and prosperity in the region through
enhanced dialog, free trade, and co-operation. The environment was iden-
tified as a major field of co-operation. A new Mediterranean Action Plan,
MAP II, was also adopted. A special consultative body to the contract-
ing parties of the Barcelona Convention, the Mediterranean Commission
for Sustainable Development (MCSD) was establishment. The MCSD pro-
duced recommendations and proposals for actions on water demand man-
agement, coastal zone management, tourism, industry, urban development,
etc.[2,3].
Interestinglyenough,overthelast30yearstheMediterraneanSeaisprob-
ably the marine area for the protection of which the largest international
co-operation has developed. Although great progress has been achieved in
various areas, it is generally admitted that these efforts have not yet re-
ceived the support from the general public and stakeholders that was ex-
pected. One of the reasons is probably the difficulty in providing relevant
6 L.Laubier
informationonthoselargeprojectsofinternationalinitiativestotheMediter-
ranean public at local tonational levels. Another reasonis the relatively low
Mediterraneanpublicawarenessofenvironmentalprotectionandsustainable
development.
2
TheMediterraneanSeaanditsRegion
Located half way between the temperate and subtropical zones and sur-
rounded by large continents, the Mediterranean region has a climate with
hot dry summers, mild winters, and a wet fall and spring. Its landscapes
and monuments are the greatest tourist attractions in the world. Urban de-
velopment has been particularly strong along the coastline, accommodating
bothpermanentandtemporarypopulations,whichinturnhavesubstantially
modifiedthecoastline[4].
Thehighlyindustrializedcountriesinthenorthstronglycontrastwiththe
countries in the south. This situation has significant consequences on envi-
ronmentalissues,particularlythoserelatedtotransboundarypollution.
2.1
GeographicSetting
The Mediterranean Sea has an extension of 3.5×106km2, nearly 1% of the
world ocean, and an average water depth of 1.5km. Its maximum depth in
the Matapan trench is 5121m. The length of the basin along the east-west
axis is 4000km, with a maximum width of 800km. The coastline length is
46000km,ofwhich40%represents islands. Itiscommonlydividedintotwo
major basins (east and west basins) and eleven sub-basins as indicated in
Table1.
The Mediterranean Sea is connected to the Atlantic Ocean through the
StraitofGibraltar(width12.8km,depthover300m),whilethenorth-eastern
partisconnectedwiththeBlackSeathroughtheStraitofDardanelles(depth
97m), the Marmara Sea, and the Strait of Bosphorus. In the SLE, the man-
made Suez Canal links the Mediterranean with the Red Sea, offering an
entrancefortropicalspeciescomingfromtheRedSeaandIndianOcean(so-
calledlessepsianspecies).
ThemainriversaretheRhôneriver(France,averagedischarge1721m3s–1,
no change from 1960 to 2000); the Po river (Italy, average discharge
1569m3s–1, no change from1960 to 2000); the Nile river (Egypt, 873m3s–1
between 1973 and1982, 1542m3s–1 from 1912 to 1982, change –43%); the
Ebro river (Spain, average discharge 416m3s–1, change from 1960 to 2000
–53.8%).
MediterraneanSeaandHumans:ImprovingaConflictualPartnership 7
Table1 ListoftheelevenMediterraneansub-basins
Sub-basin Code Borderingcountries
1.Alboran ALB Spain,Morocco,Algeria
2.North-Western NWE Spain,France,Monaco,Italy
3.South-Western SWE Spain,Italy,Algeria,Tunisia
4.Tyrrhenian TYR Italy,France,Tunisia
5.Adriatic ADR Italy,Croatia,Albanian
6.Ionian ION Italy,Albanian,Greece
7.Central CEN Italy,Tunisia,Libya,Malta
8.Aegean AEG Greece,Turkey
9.North-Levantine NLE Turkey,Cyprus,Syria,Lebanon
10.South-Levantine SLE Lebanon,Israel,Egypt,Libya
11.MarmaraSea MAS Turkey
2.2
HydrodynamicSystem
The hydrological regime of the Mediterranean rivers is very particular. Dif-
ferencesbetweenlowandhighwaterdischargescanbeextreme.Inthesouth,
most of the water discharge occurs during short floods (flash floods). Main
rivers located in the north are fueled by precipitations occurring on rather
large areas, while intense rainfall falling on small catchments is the main
causeoffloodsinshortriversfromtheMediterraneanarea.
Theartificialdammingofriversmainlyoccurredduringthesecondhalfof
thelastcenturyforhydroelectricity,landirrigation,andpublicwatersupply,
andhashadaconsiderableimpact onthenatural system. Asaresult,strong
reductions of water discharge (around 54% in the Ebro river) are presently
occurring.Long-termtrendscanbeestablished forsome30riversforwhich
reliable records of more than 7 years are available [5]. In most cases, clear
negativetrendsareprominentoverthelast70years.
At regional level, water discharge reductions vary according to the sub-
basin, the highest reduction being recorded in the SLE sub-basin due to
the Aswan dam (today, the river Nile discharge represents around 5–10%
of the situation at the beginning of the last century), while the ADR sub-
basinstillreceivesmorethanone-thirdoftheoverallfreshwaterinput(about
140km3/yr). The NLE, NWE, and ADR sub-basins are the least affected by
the reduction (about 10–20%), whereas the dropis larger in TYR, ION, and
AEGsub-basins(25–50%).TheALBsub-basinshowsthestrongestreduction
(about75%).Thereductionratefrom1920to1970wasmoreorlesssimilarin
allsub-basins,whiledifferencesappearedtowardstheendofthe20thcentury.
From1970 to1995 thegeneral trendofdecrease offreshwater dischargewas
accelerated, and the overall reduction was around 110km3/yr.This is com-
8 L.Laubier
pared with a reduction of 170km3/yr during the first period of 50 years,
although this period was affected by the closure of the Aswan dam [3]. As
awhole,from1920to1995,thefreshwaterdischargetotheMediterraneanby
rivers was actually about 330km3/yr compared to about 600km3/yr at the
beginningofthelastcentury.SimilarfigureshadbeengivenbyBoukhtirand
Barnierwithadecreasefromabout600km3/yrtoabout350km3/yr[6].
The average discharge of the two northern rivers, the Rhône and Po (as
well as the Danube river) has remained more or less constant, thus increas-
ing their contribution tothereduced totalfreshwater dischargefrom17% at
the beginning of last century to about 30%. This relative stability is in good
agreementwiththerainfallregime.
The Mediterranean Seaisawell-knownexample ofan evaporation basin,
withanegativebalancewiththeAtlanticocean.IftheGibraltarStraitbecame
closed,theMediterraneanlevelwoulddecreaseatarateofabout0.5–1m/yr.
As early as the 1980s, it was estimated that Atlantic surface water of low
salinityenters theMediterraneanatarateof1.2×106m3s–1,whileMediter-
ranean deep water of higher salinity goes out to the Atlantic at a rate of
1.14×106m3s–1 [7]. More recent estimations indicate that the Atlantic sur-
face water inflow is about 1×106m3s–1, the Mediterranean deep water out-
flow being 90% of the Atlantic surface water inflow, although water budget
estimatesgiveahighervalueofupto1.6×106m3s–1(thisvolume,seecontri-
butionsbyC.MillotandJ.-P.Béthouxetal.)[8].Duringsummer,thesurface
waters are characterized by a thermocline, whose depth, temperature gradi-
ent, and durationincrease slowly fromthewesterntotheeastern basin. The
deepMediterraneanwaters(from250mtomaximumdepth)areveryhomo-
◦
geneous,withatemperatureofabout12.80 Candasalinityofabout38.2.An
◦
increaseof+0.12 Cand+0.05insalinityhasbeenrecordedduring thelast
40years. Duringwintertime,deepwaterformationoccursinseveralsurface
areascooledandevaporatedbynorthernwinds.Verticalmovementsreaching
around10cms–1mayoccurforseveraldays.Recentresultsshowthatmostof
thisprocesstakeplaceintheeasternbasin,althoughitwasinitiallyanalyzed
inthenorth-westernbasin.Residencetimeofwatersinthewesternbasinhas
recently been estimated to be 15 years whereas it is around 50 years in the
easternbasin(seecontributionbyBéthouxetal.,thisvolume).
2.3
MarineBiodiversity
The whole Mediterranean Sea shows a high biological diversity, with about
10000–12000marinespecies(bacteriaexcluded);speciesnewtoscienceare
still regularly described and added to this total. Compared with the world
ocean fauna, the Mediterranean Sea contains about 7% of the known world
marine fauna and 18% of the known world marine flora. The most typi-
calcoastalcommunities arerepresented by thesea-grass Posidonia oceanica
MediterraneanSeaandHumans:ImprovingaConflictualPartnership 9
Table2 Decreaseofspeciespercentagewithincreasingdepth
Zones Depth Species
(m) %
Infralittoralzone 50 63
Circalittoralzone 100 44
Bathyalzone 150 37
Bathyalzone 200 31
Bathyalzone 300 25
Bathyalzone 500 18
Bathyalzone 1000 9
Abyssalzone 2000 3
ecosystem whichextends to adepth of25–40m depending onwater turbid-
ity. This is followed by the coralligenous ecosystem built up by calcareous
red algae, which constitute the most spectacular underwater seascape of the
Mediterraneanandextendstoatleastadepthof40m(westernbasin)to70m
(easternbasin)duetoincreasingtransparencyofcoastalwaters.
The biodiversity is much higher in the western basin than in the eastern
basin, where the 600 hundred or so species that entered the Mediterranean
throughtheSuezcanal(calledLessepsian migrants)arenotsufficienttobal-
ancethewest-eastdecreasingbiodiversitygradient.TheMediterraneangreat
depths (2000–5000m) are extremely poor in both species and individuals,
whichispartlyduetotherecent geologicalhistoryoftheMediterraneanSea
(Messiniancrisis,5.5millionyearsago)andpartlytothethermohalinechar-
acteristics of the Mediterranean deep waters. Table2 shows the percentage
reductionofspecieswithdepth[9].
3
HumanActivitiesandPressures
This section describes the Mediterranean Sea and its coastal zone by re-
viewing the human activities, including urbanization, tourism, loads and
discharges from agriculture, fisheries and aquaculture, industries, and mar-
itime traffic together with the main threats. Problems and success in policy
andmanagementimplementationarealsodiscussed.
Thestartingpointisthepopulationissue,withitsgrowthscenarioswhere
north-south and urban versus rural development trends are clearly visible,
enhanced in the northern part of the region by strong seasonal/tourism-
inducedvariations,especiallyalongthecoastline.
10 L.Laubier
3.1
DemographicTrendsandUrbanDevelopment
The population of the coastal states of the Mediterranean has increased
rapidlyduringthelast40years:itwas246millionin1960and380millionin
1990.In2000,thecountriesborderingtheMediterraneanSeahadatotalpop-
ulation of about 430 million people. The distribution of population between
thenorthernandsoutherncountriesvariesdramatically:in1950, thenorth-
erncountriesrepresented two-thirdsofthetotalpopulation,whiletodayitis
only50%,andmaybeone-thirdin2025.Alargenumberofthemlivedirectly
in the coastal zone. Coastal population densities vary from 20 along coastal
Libya to more than 1000/km2 in the Nile delta. These figures are compared
withdemographicprojectionsfortheyear2025[3,10].
Table3 PresentMediterraneanpopulationandprojectionforyear2025
Population Density
Country Area 2000 2025 Trend Med/Tot∗
(km2) (Thousandinhabit.) (%) (Total
inhabit./km2)
Albania 28748 3114 3820 +22.7 113 1.29
Algeria 2381741 30332 42329 +39.6 10 22.21
BosniaH 51129 3972 4324 +8.9 87 0.58
Croatia 56538 4473 4193 –6.3 87 0.58
Cyprus 9251 54 1.00
Egypt 997739 66007 94895 +43.8 59 3.54
France 547026 59412 64177 +8.0 103 1.20
Greece 131944 10558 10393 –1.6 78 1.18
Israel 20770 5851 7861 +34.4 263 2.98
Italy 301277 57456 53925 –6.1 190 1.04
Lebanon 10230 3206 4147 +29.4 293 1.88
Libya 1759500 6038 8832 +46.3 3 8.28
Malta 316 389 430 +10.5 1145 1.00
Monaco 2 34 41 +20.6 15000 1.00
Morocco 710850 28505 38174 +33.9 37 2.39
Palestine 6165 3150 6072 +92.8 365 6.33
Slovenia 20251 1965 2029 +3.3 100 0.57
Spain 504783 39815 40769 +2.4 78 2.13
Syria 185180 15936 24003 +50.6 77 4.23
Tunisia 154530 9615 12892 +34.1 57 2.37
Turkey 779452 65627 87303 +33.0 72 1.28
TOTAL 8759422 426311 522826
∗
Ratioofpopulationdensity ontheMediterraneanpartofthecountryoverthatinthe
entirecountry.
MediterraneanSeaandHumans:ImprovingaConflictualPartnership 11
The demographic trend couldadd about 96 million people to the perma-
nent population of the Mediterranean riverain countries, of which a large
majority will be settled in the coastal strip. This will have an important im-
pact on urban development. The present rate of increase averages 1.3% per
annum, but is showing a tendency to diminish, mainly due to a decrease in
thebirthratewhichbeganinthe1970s. Populationgrowthshowsimportant
differencesbetweennorthandsouth.ThenorthernEuropeancountrieshave
nearly stable populations. In contrast, population increase in the southern
countriesrangesfrom1.5tomorethan3%peryear.Thepopulationisbecom-
ingyounger,whichcreatesincreasedproblemsofeducationandjob-creation
inthosecountries.
3.2
Tourism
TheMediterraneanregionbecameattractivetotouristsinthemid-nineteenth
century mainly because oftheregion’sculturalheritage, thebeauty andvar-
ietyofthesurroundingcountryside,anditsmildclimateandspeciallifestyle.
Upuntilthe1930s,touristsweregenerallywell-offandratherfewinnumber.
Theeffectonthelocalenvironmentanditsinhabitantswasrelativelysmallat
thattime,althoughitdidleadtothebeginningofurbanizationoftheregion
(e.g.,theFrench“Riviera”).
Fromthe1930s onwardandespecially after theSecondWorldWar, mass-
tourism started to develop mainly due to increased incomes in many coun-
tries, paid holidays, and more leisure time. The development of transport
facilitiesconcentratedthismovementintheseasideareas.
Atpresent,theMediterraneanregionisthemostimportanttouristregion
intheworld,accountingfor30%ofinternationaltouristarrivalsandfor25%
of the receipts from international tourism. Tourism, both international and
domestic, is one of the most active sectors of the region, and up to now has
been very affected by the unevenness of economic growth in the countries
oforigin.TourismisamatterofinterestforallMediterraneancountriesthat
have ambitious plans to develop international as well as domestic tourism.
Alltogether,6millionpeoplearepresentlyemployeddirectlyorindirectlyby
tourism.
According to Blue Plan scenarios, the number of tourists in the Mediter-
ranean countries will increase from 135 million people in the year 1990 to
235–353millionpeopleintheyear2025.ThemajorityofthemwillbeofEuro-
peanorigin.Abreakdownofarrivalsbynationalitiesfortheyear1993showed
that out of the 160 million international touristsvisiting the Mediterranean,
24%camefromMediterraneancountries.
Mediterraneantourismisincreasinglyconcentratedonthecoast.Insome
countries,coastaltourismrepresentsupto90%ofalltourism.Itisalsoheav-
ilyseasonal,thehighseasonofaboutthreemonthsculminatinginfourweeks
12 L.Laubier
of very heavy activity, around mid-July to mid-August, which leads to an
under-utilization of lodgings and other facilities during most of the year. At
present,thenorth-westernMediterraneandominatesthetourismmarket;ac-
cordingtoBluePlanscenarios,thiswillcontinueoverthenext25years[1].
Tourism development implies environmental protection. Environmental
awarenessamongsttourists,particularlyfromnorthernEurope,isincreasing.
Interactionsbetweentourismandenvironmentarenumerous:landuse,con-
sumptionofwaterresources,pollutionandwaste,physicalandsocio-cultural
pressures. Forlocalpopulations, theseissues oftenresultinabandonment of
traditional activities, degradation of the coastal and marine ecosystems, de-
terioration of human conditions, unemployment and poverty, deterioration
ofhistoricalsites,etc.Inrecentyears,therequirementsoftourismitselfhave
producedastrongincentiveforprotectionofthelandscapeandthequalityof
theenvironment.
Theimportanceoftourismhasbeenacceptedasoneofthemajorissuesfor
the region;theMediterranean CommissiononSustainable Development has
selecteditasoneofitsprioritythemes.Itisgenerallyrecognizedthattourism
couldmakeamuchgreatercontributiontotheprotectionandmanagementof
thehistoricalandnaturalsitesthatitexploits.
3.3
UrbanSewageOutfalls
Uncontrolled discharges into the sea result in degradation of the quality of
marine ecosystems (mainly benthic communities) due to the release of nu-
trients and organic and inorganic pollutants, toxic effects on aquatic fauna
and flora, and dispersion of pathogenic bacteria generating risks for human
health. Varioustypesoftreatment areused, fromthesimplest (primarysed-
imentation) to the most sophisticated (activated sludge plus filtration and
ultravioletdisinfectanttreatment).Physical/chemicaltreatmentiscommonly
usedinMediterraneancountries;recenttechnologiesenablereductionofthe
nitrogenandphosphorusloads(e.g.,themodernIzmirtreatmentplantoper-
atingsince2001).Theefficiencyofthedifferenttreatmentsisevaluatedusing
thebiologicalandchemicaloxygendemands(BODandCOD).Thepollution
introducedintheseabyurbanstormwateristakingonagreaterimportance.
During rainy weather, urban waste waters are composed of the overflow
from combined systems and direct discharges of urban storm water in the
caseofseparatesystems.Urbanstormwaterispollutedbydustandwastesac-
cumulatedontheroadsystemandmayhavesignificantpollutionloads.Upto
nowithasbeenconsideredasunpollutedoronlyslightlypollutedsoitisof-
tendischargedintheclosevicinityofcitiesinordertoavoidfloods.Dataon
loadsofmetals,hydrocarbons,andothermicropollutants(mainlyherbicides)
inurbanstormwater areextremely variable. Using theimpermeable surface
area per inhabitant (around 0.006ha in two case studies, Marseilles and Tu-