12 Operational pollution fromshippingSources, environmental impactand global contributionGillian ReynoldsIntroductionPollution from shipping has traditionally been thought of in terms of oil pollu-tionresultingfromcatastrophictankeraccidents,orsmallerslicksassociatedwithday-to-dayshipoperations.Generallylessnewsworthy,butrecognisedinternationallyasasourceofpollutionsincethe1970s,hasbeenthelossofother environmentally damaging cargoes carried in chemical tankers or in con-tainers,andthedischargeofship-generatedwastes,primarilysewageandgarbage.The ship itself as a source of pollution received scant consideration until theearly1990s,whenrstairpollution,andsubsequentlyantifoulingpaintsandballastwater,wereaggedasmajoroperationalpollutants.Itisnowacknow-ledgedthatshippingisassociatedwithabroadrangeofenvironmentalissues(Figure12.1).Mostland-basedenvironmentalconcernsincludingsewage,garbage,exhaustemissions,volatileorganiccompounds,chlorouorocarbons(CFCs) and halon reghting media are associated with shipping. But beyondthis, ships give rise to additional concerns relating to: damage to the hull and loss of fuel oils or cargo; the transfer of live organisms and chemical pollutants in ballast water; and coating of the hull with biocides to keep it free of fouling.Ship-generatedpollutantsareassociatedwitharangeofenvironmentalimpactsandmaybeofconcernatalocal,regionaland/orgloballevel.Allstagesoftheshipslifecycle,fromconstructionthroughtoscrapping,impacton the environment. However, this chapter will focus on day-to-day operationsbecausealthoughtheywererelativelyneglecteduntilrecentlytheyarewidelyconsideredtobeofgreatestsignicanceintermsofemissionsanddis-chargestotheenvironment.Againstthisbackground,thechapterisprimarilyconcerned to demonstrate the breadth of the problem of shipping-related pollu-tion and the challenges still to be met. To do so, discussion is structured aroundthefollowingpollutioncategories:emissionstoair,dischargestowaterandwaste streams. Accidental pollution is largely excluded.Emissions to airExhaust emissionsComposition and environmental impactOfprimaryinterestareexhaustemissionsfromdieselengines,currentlythemajorproviderofpropulsivepowerinthemarineindustry.Emissionslargelycomprisenitrogen,oxygen,carbondioxide(CO2)andwatervapour,togetherwithsmallerquantitiesofcarbonmonoxide,oxidesofnitrogen(NOx),oxidesofsulphur(SOx),partiallyreactedandnon-combustedhydrocarbons,andpar-ticulate material (Figure 12.2). Trace quantities of organic micropollutants suchaspolyaromatichydrocarbons(PAHs),dioxinsandheavymetalsarealsopresent.OfespecialconcernareNOx,SOxandCO2,plusparticulatematerialandvarious micropollutants. The formation of oxides of nitrogen occurs as a resultoftheoxidationeitherofmolecularnitrogenincombustionair,oroforganicnitrogeninfuel.Nitricoxide(NO),theprincipalreactionproduct,nitrogendioxide(NO2)andnitrousoxide(N2O)areprimarilyformed.Adverseeffectsdue to NOxare diverse: NO2 affects respiration and vegetation, as well as con-tributing signicantly to acid deposition. NOxand volatile organic compounds(VOCs) can produce tropospheric ozone, which adversely affects human health,cropyieldandnaturalvegetation.Atagloballevel,N2Oplaysasmallroleinboth stratospheric ozone depletion and global climate change.Carbondioxideandoxidesofsulphurderive,respectively,fromtheoxida-tionofhydrocarbonsandsulphurinthefuel.Oxidesofsulphurprincipally234 Gillian ReynoldsFirefightingmediaGarbageOilSewage Antifouling paint Ballast waterCargospillagesor lossesoverboardExhaustemissionsRefrigerantgasesCargo vapouremissionsFigure 12.1 Operational pollution from shipping.consist of sulphur dioxide (SO2), with much lower quantities of sulphur trioxide(SO3).ConcernoverSO2emissionsarisesfromtheirdetrimentalimpactonhumanrespiration,vegetationandbuildingmaterials.Althoughtraditionallynot regarded as a pollutant, CO2has become of increasing concern because ofits importance as a greenhouse gas and the possibly far-reaching consequencesof rising CO2concentrations for global climate change.Theparticulatefractionofexhaustgasesrepresentsacomplexmixtureofinorganic and organic substances largely comprising elemental carbon, ash min-eralsandheavymetals,plusavarietyofnon-orpartiallycombustedhydro-carbonsfromshipsfuelandlubricatingoils.Anintermittentdischargeofaccumulateddepositsfromtheexhaustsystemmayalsobeencountered.Withthe exception of the latter, the majority of diesel particulates are likely to be lessthan 1m in diameter, readily transportable by air currents and of low settlingvelocity. Potentially detrimental effects may thus be encountered away from theimmediatevicinityoftheexhaustgasplume.Althoughstudyofthemarinediesel particulate composition is limited, the extrapolation of results from otherdieselapplicationswouldsuggestthatnotonlygeneralrespiratoryproblems,but also more serious toxic, mutagenic and carcinogenic effects, may be associ-ated with these emissions.Thetermmicropollutantsgenerallyreferstothosepollutantspresentintrace quantities, typically at the parts per billion level, which demonstrate severeadverse effects even at low concentrations. In the context of diesel exhaust emis-sions,micropollutantsencompassbothorganicmicropollutantsandheavymetals. The former typically include such trace organic contaminants as polyaro-maticPAHs,dioxinsandfurans.Withrespecttocombustionprocesses,thepresence, and in many cases carcinogenicity, of PAHs in the exhaust gas streamarewelldocumented.HighlymutagenicnitratedPAHshavealsobeenidenti-edandarebelievedtooriginatefromchemicalreactionbetweenPAHandOperational pollution from shipping 235ParticulatesHydrocarbonsNOxN2O2CO2H2OCOSOxFigure 12.2 Marine diesel exhaust emission composition.NOxin the exhaust gas system. In addition, highly toxic emissions of polychlo-rinatedbiphenyls(PCBs),polychlorinateddibenzodioxins(PCDDs)andpoly-chlorinateddibenzofurans(PCDFs)havebeenreported(LloydsRegister1993).1Heavy metals include many transition elements such as cadmium, chromium,copper, mercury, nickel and zinc; some non-transition metals such as lead; andthemetalloidsarsenicandselenium.Thepresenceoftheseelementsinmarineexhaustemissionsgenerallyreectsconcentrationsintheoilfuelscombusted.Thisinturnreectsthecomponentoilblendsplusanyelementsincorporatedduring storage and transfer, but minus those removed in the course of onboardtreatment.Thesignicanceofheavymetalsisthattheyarewell-knowninhibitorsofbiologicalprocesses,withtoxiceffectsmediatedthroughthepoisoningofenzymesinvolvedinbiochemicalreactions.Consequently,theirwidespreadimpacts range from reduced diversity of aquatic ecosystems, through sh kills torenal dysfunction and cancer in humans.Marine emissions estimatesThefocusonmarinedieselexhaustemissionsthroughoutthe1990swasaccompaniedbysignicantprogressinconstructinginventoriesofkeycom-ponents.Internationallyacceptedemissionfactorswereestablished(LloydsRegister1995).Detailedmethodologiesforconstructinginventoriesofshipemissions were developed by the UNECE Task Force on Emission Inventoriesand published in the Atmospheric Emission Inventory Guidebook (EEA 2002).Anumberofinventorieswereundertakenonbothregionalandglobalbases(Table12.I).Despitevariationsintheresults,2comparisonofglobalemissionsfrom shipping with those from all other sources indicates that marine emissionsofCO2,NOxandSOxamounttoaround2percent,1015percentand46per cent respectively of global anthropogenic emissions (Endresen et al. 2003a).Beyondthis,thereisageographytothepollution:mostship-generatedemis-sionstakeplaceinthenorthernhemisphere.Corbettetal.(1999)reportthat85percentofshippingemissionsoccurthere,with52percentimpactingonthe North Atlantic and Northern Europe, and 27 per cent on the North Pacic.Some information also exists on regional and global estimates of other emis-sion components of signicant environmental interest, for example PAH, heavymetals and nitrous oxide (N2O). However, the emission factors on which theseestimates are based tend to be derived from very limited data sets, and/or to beadopted from other industries or transport modes. Consequently, they must betreated with caution.Control mechanismsMechanisms for controlling diesel engine exhaust emissions tend to focus eitheronspecicallyreducingSOxorNOxemissions,orontheintroductionoffuel236 Gillian ReynoldsTable 12.1Summary of shipping exhaust emission estimates (M tonnes/annum)ReferenceBase yearNOxCOHydrocarbonsSO2CO2WorldwideEndresen et al. (2003a)1996/200010.8/11.91.0/1.10.33/0.36 6.1/6.8461/501(NMVOC)Ship & Ocean Foundation 1997387(2001)Skjlsvik et al. (2000)199610.31.00.33 (NMHC)5.84380.04 (CH4)Corbett et al, 1999199310.1 8.5Olivier et al. (1996)19908.6a0.10.02 (CH4)4.9350Lloyds Register, pers. 199011.36.4comm. (2002)Bremnes (1990) and Melus19865.0854.58European areaNorth Sea/BalticWhall et al. (2002)20001.0740.0390.76341North SeaJerre et al. (1994)19900.269Southern North SeaCONCAWE (1994)19920.206NE Atlantic, Black and Mediterranean SeasWhall et al. (2002)20002.5430.0951.815116NE AtlanticLloyds Register (1995)19901.940.170.041.37Baltic SeaLloyds Register (1998)19900.350.030.0080.23Baltic Sea Alexandersson et al. (1993)19870.1630.084Mediterranean and Black SeasLloyds Register (1999)19901.730.150.041.25Sources: Individual references citedNote:aAmended gure, T.G.J. Olivier, personal communication (2002).economymeasuresthatprovideacross-the-boardemissionreduction.Thereare two approaches to reducing SOx: reducing fuel sulphur content and treatingtheexhaustgasstream.Reducingfuelsulphurlevelscanprovidebenetsintermsofreducedmaintenancecostsandincreasedreliabilityandavailabilityofthe engine. There are also savings associated with the reduced requirements forfuel treatment equipment and the absence of quantities of sludge. These bene-ts are, however, associated with the combustion of cleaner fuel such as marinediesel oil rather than the use of desulphurised residual fuel. Moreover, problemsmay be encountered with the availability and high cost of low-sulphur distillatefuel.Exhaustgascleaningsystemshavereceivedlittleattention,owingtocon-cernssuchascorrosionproblemscausedbythegenerationofdilutesulphuricacid, and the washing of other emission components particularly highly toxicorganic micropollutants and heavy metals into the marine environment. Ship-boardtrialsarebeinginitiated,however,andthesemaydemonstratethatexhaust gas cleaning is a viable approach to SOxemission control.AswithSOx,therearecurrentlytwodifferentapproachestoreducingNOxemissions.Primarymethodsinvolveeithermodicationstotheengineortheintroduction of pollution-reducing substances into it. Secondary methods treatthe exhaust emissions generated.Primarymethodsincludeoptimisingfuelinjectionandignitiontiming,exhaust gas recirculation, the use of fuelwater emulsion, direct water injectionandthehumidairmotorconcept.Althoughthereisanextensiveliteraturerelatingtothesemeasures(BMT2000;Croner2000;Marintek2000;MER1999;Fleischer1996),theinformationpresentedisoftenconictingintermsoftheeffectivenessofNOxreduction.Moreover,mostmeasuresappeartobeassociatedwithincreasedfuelconsumption,whichisneitherenvironmentallynoreconomicallyrecommended.TheuseofNOx-optimisedslidevalvesdoes,however, appear to be an exception: both NOxreduction and fuel savings havebeen reported. Even so, all data are very preliminary and are rarely based on in-service experience.Possible secondary methods of NOxcontrol include selective catalytic reduc-tion(SCR)oftheexhauststreamandnon-thermalplasmasystems.TheSCRsystem is currently the only available technology proven at full scale to meet 90per cent NOxreduction levels, but obstacles are that its capital investment andoperating costs are high. Moreover, analysis of through-life environmental costhas still to demonstrate an overall environmental advantage to its use.The less well known non-thermal plasma technique is potentially capable ofat least matching an SCR system in marine applications. Moreover, there is theprospectthatitwillbeasimpler,morerobustandmorecompactsystem,withouttherequirementforseparate(catalytic)consumables.Theplasmaisapartially ionised gas comprising a neutral mixture of atoms, molecules, free radi-cals,ionsandelectrons.Thisconstitutesanextremelyreactivemediumthatbreaksdowntheexhaustcomponentsintosimplermolecules.TrialsofbothSCRandplasmasystemshaveindicatedthatnon-thermalplasmascompare238 Gillian Reynoldsfavourably with SCR in terms of emission reduction efciency, costs, installationand operational efciency. The system does, however, consume approximately 5percentofthepowerproducedbytheengine,effectivelyincreasingfuelcon-sumption.The available literature provides some estimates of the costs of implementingthevariousoptionsforcontrollingNOxemissionsbut,giventhatNOxreduc-tionmethodsarenotwidelyused,reliablemarket-basedcostinformationislimited,exceptforSCRsystems.WhilecostsarelikelytofallastheuptakeofNOxemissiontechnologiesincreases,manyownersareunlikelytoinvestuntilreliabledataonthevariouscontrolmeasuresareavailable.Thetaskofmakingreliable estimates of the cost of emission abatement is further complicated as itis generally a function of operating hours and/or distance travelled. The nan-cial cost is thus dependent upon the individual ship, its efciency and its tradingpattern. For example, capital costs for SCR systems have been calculated to varyfrom$27,500tonearly$1.8million,withannualoperatingcostsrangingbetween$8,000and$533,000dependentuponshiptypeandinstalledpower(BMT 2000).In addition to those measures specically targeted at reducing NOxor SOx,fueleconomymeasureswillachieveanacrosstheboardreductioninemis-sions. Energy savings can be obtained on new ships by good hull design and theuseofavarietyofunconventionalpropellerarrangements.Upto20percentreductionsinfuelconsumptioncanreportedlybeachievedbythesemeans,althoughsucheconomieshavebeendifculttodemonstrateinpractice.Forships in service, fuel savings of up to 5 per cent can be made through best-prac-ticemaintenancetoretainas-builthullsmoothness,andalsobymaintainingpropeller nish.Operational measures such as slow steaming, weather routing, eet planningandcargohandlingcanalsoresultinsignicantfuelsavings.Aboveall,speedreductionisthemosteffectiveinreducingemissionssincefuelconsumptionincreases with the square of the speed. Despite the economic pressures for max-imisation of asset use and fast delivery, the latter discussed by Slack in Chapter2, there may be scope for fuel savings by weather routing and speed reductionwithin the scope of client commitments. Although these measures are no doubttakenforeconomicreasons,environmentalgainsareanimportantadditionalbenet.Conversely,ofcourse,thequestforhighspeedinsomepartsoftheshipping sector detailed by Ridol in Chapter 8 currently entails signicantemission increases and thus environmental costs.In the longer term, design options such as measures to reduce ship resistanceby,forexample,modicationofthehullssurfacegeometryandwhaletailpropulsionareatapreliminarystageofdevelopment.Harnessingrenewableenergyisalsobeingconsideredbysome.Thegreatestpotential,however,appears to be in the use of fuel cells for propulsion and auxiliary power. Thesecouldpotentiallyprovideameansofdramaticallycuttingemissionsassociatedwithshippropulsionandon-boardelectricalgeneration.However,progressinthiscontextwillbedependentonthesourceofhydrogen.AlthoughfuelcellOperational pollution from shipping 239powergenerationinshippingisatpresenttheoreticallypossible,3capitalcostsare as yet extremely high and there are other practical problems to resolve, suchasthesafetyofhydrogenstorage.Evenso,insensitivemarkets(e.g.,ecologi-cally vulnerable areas targeted by the cruise industry; see Hall, Chapter 6) auxil-iary power provided by fuel cells could be viable for passenger ships in ten years.Refrigerants and reghting agentsEnvironmental impactChlorouorcarbons (CFCs) and hydrochlorouorocarbons (HCFCs) have, untilrecently, been in widespread use in the shipping industry as refrigerants and ininsulatingfoams.Halons(brominateduorocarbons)havealsobeenusedextensivelyasreghtingagentsinbothxedextinguishingsystemsandportable extinguishers. Both groups of compounds are now considered environ-mentallyunacceptablebecauseoftheirsignicantozonedepletionpotential(ODP) and greenhouse warming potential (GWP) (Table 12.2). Consequently,followingtheMontrealProtocolonSubstancesthatDepletetheOzoneLayerandsubsequentamendments,theuseofCFCsandhalonstheagentsofkeyconcernisnowprohibitedinnewships.ButHCFCssuchasR-22arestillpermittedinexistingplant,andR-22continuestobeusedwidely.Withthissolution still available, utilisation of the more environmentally acceptable hydro-uorocarbons(HFCs)hasbeenslowtobeadopted.Somesuccesshasbeenachievedinspecicapplicationsparticularlyrefrigeratedcontainers(R134a)and reefer ships (R407c) and, more generally, R404a. More recently, R410ahas been adopted for use in air-conditioning systems. However, the unfamiliar-ityoftheindustrywiththeserefrigerants,andconcernsovertheiravailability240 Gillian ReynoldsTable 12.2 Environmental factors for selected refrigerant gasesRefrigerant no. Name ODPaGWPbR-11 Trichlorouoromethane (CFCl3) 1.000 4,000R-12 Dichlorodiuoromethane (CF2Cl2) 1.000 8,500R-22 Chlorodiuoromethane (CHClF2) 0.055 1,700R-134a 1,1,1,2-Tetrauoroethane (CF3CH2F) 0.000 1,300R-407c Blend of R-32/125/134a (CH2F2/CF3CH2/ 0.000 1,610CF3CHF2F)R-717 Ammonia (NH3) 0.000 0R-170 Ethane (CH3CH3) 0.000 3R-290 Propane (C3H8) 0.000 3R-600 Butane (C4H10) 0.000 3Source: British Standards Institution (2000)Notesa Ozone depletion potential.b Global warming potential.worldwide,hasmilitatedagainsttheirextensiveuse.Furthermore,althoughthey are non-ozone-depleting, HFCs do have a signicant GWP and will them-selvesultimatelybephasedout.Thismayleadtoaresurgenceintheuseofnatural refrigerants, such as carbon dioxide, ammonia and hydrocarbons.Similarly, the manufacture of halon reghting agents has been phased out.Althoughtheiruseinexistingvesselsisstillpermitted,thisisgraduallydimin-ishing,owingtotheimpracticalityofobtainingadditionalhalonfortoppingup existing cylinders or replacing those that have been discharged. Alternativehalocarboncompounds(e.g.FM-200)havebeendevelopedasmoreenviron-mentally benign, but they still exhibit signicant GWP (Table 12.3), and thereare concerns on health and safety grounds due to the toxicity of their degrada-tion products. They are also expensive, and consequently their use tends to beconnedtosmallerships.Water(delugeormist),CO2orfoamarethemostfrequentlyusedalternativesatpresent,dependentupontheapplication.Replacementofhalonsystemsinexistingshipsgenerallynecessitatesreplace-ment of the entire reghting system.Marine emissions estimatesThe available data for regional or global emissions of refrigerant gases and re-ghtingagentsarelimited.However,emissionsofCFCsfromtheworldship-pingeetwereestimatedat3,0006,000tonnesin1990equivalenttobetween 1 and 3 per cent of total global emissions. Halon emissions from ship-ping for the same year were estimated to be 300400 tonnes, or around 10 percent of the world total (International Maritime Organization, personal commu-nication). Although more recent gures are not readily available, it is likely thatnewsurveyswouldshowasignicantreductioninCFCandhalonemissionsbecause of the phase-out of these compounds.Operational pollution from shipping 241Table 12.3 Environmentalfactorsforselectedgaseousre-extinguishingagentsasalternatives to halon 1301Trade name Chemical formula ODPaGWPb(100 year) Atmospheric lifetime(years)Halon 1301 CBrF31216 4,900 0,065CEA410 C4F100 7,000 2,600FE13 CHF30 11,700 0,264FM200 C3HF70 2,900 0,036.5Source: Department of Trade and Industry (2001)Notesa Ozone depletion potential.b Global warming potential.Control mechanismsControlstrategiescentrearoundtheselectionofmoreenvironmentallybenignrefrigerantgasesorreghtingmedia(seeEnvironmentalimpact,pp. 240241)combinedwitheffectiveloss-minimisationstrategies.Thelatterareparticularlyimportantforrefrigerantgases,forwhichhighleakagerateshavepreviouslybeenreported. However, leak detection and preventive maintenance are now widely prac-tised on a voluntary basis to reduce discharge to the environment from operationalsystems.VentingofrefrigerantsandCFCorHCFCfoam-blowingagentstotheatmosphereisalsoillegalundertheMontrealProtocol.Whereinsulatingfoamhasbeen blown using CFC or HCFC, the foam should be removed, degassed and thegas recovered, prior to disposal. Similarly, refrigerant gas must be recovered duringmaintenance,orpriortoscrapping,usingappropriaterecoveryequipment.Whilerecovery does generally occur during maintenance, refrigerant gas and blowing agentrecovery is unlikely to be well established in most ship scrapping facilities at present.Cargo vapour emissionsEnvironmental impactEmissions of volatile organic compounds (VOCs) from oil and chemical tankersare of increasing concern, due to the part they play in the formation of photo-chemicaloxidantssuchasground-levelortroposphericozone.Ozonehasnosignicant anthropogenic sources in the atmosphere. It, and other photochemi-caloxidants,aregeneratedbychemicalreactioninvolvingnitrogenoxidesandVOCs in the presence of sunlight.Ozoneisastrongoxidisingagentandoneofthemostaggressiveofthecommonairpollutants.Exposurecanharmhumanhealth,reduceforestryandcropyields,anddamagematerials,includingnaturalandsyntheticrubber,paints, varnishes and textiles. Ozone also acts as a greenhouse gas, although itswarming potential is uncertain.Marine emissions estimatesMost estimates of global emissions of VOCs from the handling and transport ofcrudeoilandoilproductsareintherangeof1.71.8milliontonnesperyear.This is equivalent to 0.10.15 per cent of all cargo transported (Martens 1993;Endresenetal.2003a).Emissionsaregenerallygeographicallylimited,partlybecauseoiltransporttakesplacewithinawell-denedsystemofinternationalsea routes, but also because most of the evaporation takes place during loading.Control mechanismsTheprimarymechanismforcontrolofcargovapouremissionsistheuseofvapouremissioncontrolsystems(VECS),whichacttocondensevapourand242 Gillian Reynoldsreturnittotheonshoretankorservicevessel.Thisrequirescompatibleship-andshore-basedinstallations,forwhichboththeUSCoastGuardandtheInternationalMaritimeOrganizationhavepublishedessentiallyequivalentstandards.VECSarenowcommonplaceintheUnitedStatesandtheiruseisincreasinginEurope.Asanalternativetothecombinedship-andshore-basedsystems two other innovations a self-contained shipboard VOC recovery plantandasystemthatsubstantiallyreducesVOCformationduringloadinghavebeendeveloped.Whatmaybenotedisthat,aswithslowsteamingandfueleconomy,thedriversfortheoilindustryinthiscontextmaynotbepurelyenvironmental:thecostoflossesintransitisconsideredsufcientlyserioustowarrant detailed monitoring and annual reviews in, for example, the PetroleumReview.Nonetheless,evenifthemotivationiseconomic,theconsequentialenvironmental benets are genuine.Discharges to waterBallast waterEnvironmental impactShips require ballast for stability. This is taken on and discharged as required. Inthe past a number of materials have been used as ballast, but now water, primar-ilyfromportsandcoastalareas,isusedalmostexclusively.Millionsoftonnesare transported around the world annually.Two major environmental problems are associated with ballast water: theuptakeofballastfromchemicallypollutedwaters(containing,forexample,heavymetals,persistentorganicsandnutrients)anditssub-sequent discharge into a clean environment; and the transfer of live organisms from one region to another. This is of majorconcern since, if conditions are right in the port of discharge, non-native orpathogenic organisms may survive and establish themselves. Potentially thiscanleadtoseveredisruptionofthelocalmarineecologyortheintroduc-tionofdisease,particularlyinsituationswherethenaturalpredatorsnor-mallypresentinthehomeportareabsentandconsequentlycannotkeepthe organisms in check.Thissecondproblemiswidelyrecognisedasbeingoneofthemostseriousimpactsaffectingthemarineenvironment.Manyorganismscanpotentiallybetransported in ballast water. All that is needed is for them to be present in thewater or sediment alongside the vessel when it is ballasting and be able to passthroughtheintakegrill.ManyorganismshavebeenintroducedtotheUnitedKingdom, including microscopic plankton, barnacles and Chinese mitten crabs.So far these have caused only localised problems, such as fouling of jetties, out-competinglocalspeciesanddamagingembankments.However,elsewhereinOperational pollution from shipping 243theworld,organismsintroducedviaballastwaterhavehadmajoreconomic,ecological and health impacts.The havoc caused by the introduction of the European zebra mussel into theAmerican Great Lakes is well known. Some estimates put the costs of cleaningfouled pipes and generally controlling the zebra mussel invasions at $400$500million a year in the Great Lakes alone. However, the problem is not exclusivetoNorthAmerica.IntheBlackSeaacarnivorouscombjellyshintroducedfromNorthAmericaisnowpresentinhugenumbersand,byfeedingonanchovylarvae,hascausedthecollapseofthisshery.Humanhealthcanalsosuffer: cholera is known to have been transported from Asia to Latin America inthis way, and microscopic dinoagellates, which cause paralytic shellsh poison-ing, have been introduced into Australia.Ballast water is unique among the environmental issues associated with ship-ping in that it is associated with detrimental effects caused by living organisms.Thedensitiesandcompositionoforganismscarriedbyindividualvesselsareextremelyvariable,andthereisnosimplerelationshipbetweenthequantityofballastdischargedandenvironmentalimpact.Theoriginofthewater,theenvironmental compatibility of uptake and discharge ports, and the interactiondischargedorganismshavewithnativespeciesarealsoofkeyimportanceinassessingtheriskofnon-nativeorganismsbecomingestablished.Giventhepotential threat, it is understandable that tools for estimating the potential riskof introducing non-native species have been recently developed (IMO 2002d).Discharge estimatesFor commercial reasons, vessels will strive to operate with maximum cargo andminimum ballast at all times. Ballast water capacity varies as a function of cargocarryingcapacityandshiptype,withtypicalvaluesrangingfrom25to40percentofthedeadweighttonnage(Carltonetal. 1990,1995;Hayetal. 1997;Endresenetal. 2003b).Assumingballastwateronaverageamountsto30percentofthecargotransportedannually,globaltransferquantitiesareestimatedtobeapproximately2.72.8billiontonnes(Endresenetal. 2003b;LloydsRegister,personalcommunication,2002).Thegreaterpartofthedischargeisgeographicallylimited,owingtothewell-denedsystemofinternationalsearoutes.Informationonestimatedquantitiesdischargednationallyandworld-wideispresentedinTable12.4.Informationisalsoavailableontypicaldis-chargequantitiesbydifferentshiptypes(e.g.Hayetal. 1997;Carltonetal.1990).Aswithothersourcesofpollution,variationbetweentheseestimatesmay be attributable to factors such as the use of different base years, calculationmethodologies and eet segments.Control mechanismsBecause the potential seriousness of the ballast water problem is acknowledged,international regulations to lessen the risk of introducing non-native organisms244 Gillian Reynoldshavebeenunderdiscussionforoveradecade(IMO1997).Atpresenttheprimarymethodforcontrollingsuchtransfersisbymid-oceanballastwaterexchange. This relies on the fact that deep ocean water contains few organismsand those that do exist are unlikely to survive removal to a coastal or freshwaterenvironment. However, the exchange procedure can be a hazardous operation.Fewshipshavebeendesignedwithballastexchangeatseainmind,andtheprocess of pumping out and relling tanks in sequence can compromise longitu-dinalstrengthiftheshipisnotdesignedwiththisinmind.Also,ifseacon-ditionspickupwhenthetanksarepartiallyemptied,sloshingdamagecanoccur. In some cases, bulkheads can be completely destroyed.Thealternativetosequentialexchangeiscontinuousushinginwhichatleastthreetimesthetankvolumeispumpedthroughthetank.Butthispro-cedure is not ideal, since it can leave behind much of the sediment that tends tohost the most undesirable organisms. It can also be impractical, because ballasttankairpipesarenotdesignedforcontinuouslyoverowingballastwater.Itmaythereforebenecessarytoroutetheoverowthroughopenedmanholes,butthisisnotalwaysfeasible,particularlywherethesearelocatedinholdsorstorerooms.Otheroptionsforcontrollingthetransferoforganismsarecon-sequentlybeinginvestigated.Theyincludetheretentionofballastwateronboard; designs which eliminate the need for ballast water; discharge to receptionfacilities;andtreatmentbyltration,ultravioletirradiation,chemicaldisinfec-tionorheat.Whilethereareisolatedcasesofwatertreatmentplantbeinginstalledonships,effectivecommerciallyapplicabletechniquesaresomewayOperational pollution from shipping 245Table 12.4 Ballast water discharge estimatesaVolume Referencedischarged(M tonnes/annum)USA 0,079 Carlton et al. (1995)0,101 Endresen et al. (2003b)Australia 0,121 Australian Bureau of Statistics (1997)0,058 Jones (1991)0,098 Endresen et al. (2003b)New Zealand 0,0 3.75.0 Hay et al. (1997)Netherlands 0,0 7.5bGotje et al. (1998)0,026 Endresen et al. (2003b)Worldwide 3,0005,000 IMO, pers. comm. (2002)2,700 Endresen et al. (2003b)2,800 Lloyds Register, pers. comm. (2002)Sources: Individual references citedNotesa Variations between estimates may be attributable to factors such as the use of different base years,calculation methodologies and eet segments.b Stated to represent 42 per cent of ballast water discharged in Europe.off.Intheinterim,ballastwaterexchangeatseaislikelytoremainthemostwidely used option.Antifouling paintsEnvironmental impactAntifouling systems are applied to the wetted surface of ships hulls to preventsettlementofmarineorganisms,thusaidingfuelefciency.Thesesystemsaretraditionally paints containing one or more biocides which act to kill organismsattemptingtosettleonthehull.Theymayalsobenon-biocidalnon-stickcoatings or systems working on a different principle altogether, but the marineenvironmentalimpactofcoatingsgenerallyrelatestotheirbiocidalcontent.4Theactivecomponentsintheseareprimarilytributyltin(TBT),copperandorganic booster biocides such as triazines. Conventional coatings emit biocidesconstantly, and 8090 per cent will leach into the sea within three to ve years.Since its introduction in the late 1960s, TBT has been the most effective andmostwidelyusedantifoulant.Whileitisintendedtoactatthesurfaceoftheshipshull,TBTwillleachintotheseaandaccumulateinthebiotaandsedi-ment. Adverse impacts were initially reported in the 1970s, particularly in com-mercialoysterbeds,wheresevereshellmalformationswereapparent,makingtheoystersuntforhumanconsumption.Populationlevelsalsodeclined,leading to multi-billion-dollar losses in the mariculture industry. TBT was sub-sequentlyfoundtoberesponsibleforthedeclineofthedogwhelk,Nucellalapillus, in the vicinity of marinas exposure resulting in the inability to repro-ducefollowingthedevelopmentofmalesexualcharacteristicsbyfemales(imposex).Discharge estimatesIthasbeenestimatedthatTBT-basedantifoulingpaintisusedon70percentoftheworldseet(MayellandSwanson1998).WhileIsenseeetal. (1994)estimatedannualTBTinputtothemarineenvironmenttobebetween1,400and2,400tonnes,EndresenandSrgrd(1999)calculatedthatin1996theglobal input mainly from oil tankers, bulk carriers and general cargo vessels wasintherange7501,500tonnes.Thiscalculationwasbasedonaleachingrateof24g/cm2/dayandanestimatedtotalwettedareaofabout148million m2.Because attention has focused on TBT, few data are available on the input ofotherantifoulingbiocidesintothemarineenvironment.However,bydeni-tion,anybiocideusedforantifoulingpurposesislikelytohaveanadverseenvironmentaleffect.Consequently,withtheplannedphasingoutofTBT-basedpaints(seethefollowing)itisbecomingincreasinglyimportanttomonitorrisinginputsofotherbiocidesfromalternativeantifoulingcoatings.Howthiscanbedoneeffectivelyisuncertain;however,itmaybepossibleto246 Gillian Reynoldsderiveanapproximationfromthebiocidecontentofpaintsoldformarineapplication.Control mechanismsConcernovertheinputofTBTintotheenvironmenthasledtotheInter-nationalMaritimeOrganisationsInternationalConventionfortheControlofHarmfulAnti-foulingSystemsonShips(IMO2001).Thisshouldensuredecreasing inputs of TBT into the marine environment. Yet at present none ofthe alternatives provides a clearly preferable alternative solution. There are alsoimplications for atmospheric pollution. It has been estimated that a switch fromTBTtomoderntin-freecoatingswouldattractanenvironmentalpenaltyofaround 5 million tonnes of CO2resulting from the increased fuel requirementsassociated with the current performance of alternative antifouling coatings rela-tive to TBT-based paints.Currentlythemainalternativesarecopper-basedpaints,butthesestillcarryenvironmentalrisks,andtheirconcentrationsinthemarineenvironmentarelikelytoriseastheuseofTBTdeclines.Non-stickcoatings,whichpreventadhesionoffoulingorganisms,havebeenunderdevelopmentforsometime.Althoughthesearebeginningtobeusedcommercially,experienceofapplica-tionandperformanceinserviceislimited.Theyarealsorelativelyexpensive.Natural biocides provide another possibility, but they are far from the commer-cial marketplace. A different approach the physical removal of fouling by peri-odicscrubbingisconsideredbysometobeapotentialshort-termsolution.Popular though this is with some environmentalists, however, the feasibility andcosts of establishing sufcient scrubbing capacity, as well as the overall environ-mental effects, are uncertain.OilSources and scale of pollutionThe public commonly associates marine oil pollution with losses of crude oil orrened petroleum products as a result of tanker groundings and collisions. BestknownareincidentssuchasthoseinvolvingtheTorreyCanyon andExxonValdez, which respectively spilled 107,000 tonnes of oil off the coast of Corn-wall,England,in1967and30,000tonnesintoPrinceWilliamSound,Alaska,inMarch1989.Partlybecauseofthepublicperceptionfactor,moreinforma-tiononaccidentialspillagesisavailablethanforanyothercause.Forexample,the International Tanker Owners Pollution Federation makes available a regu-larly updated database of oil spilled in the marine environment (ITOPF 2002).Similarly, Oil Spill Intelligence Report (Aspen, weekly) provides information onaccidental pollution from marine transport.In reality, tanker accidents are responsible for only a minor proportion of oilenteringthemarineenvironment.PrecisedataforothersourcesarerareOperational pollution from shipping 247compared with those for accidents, but a 1990 survey showed that as much as50 per cent of the oil entering the seas and oceans was land based (Table 12.5).Moreover, little more than 20 per cent of ship-generated oil pollution was theconsequenceofaccidents,theremainderbeingcausedbydischargesduringnormal ship operations (Table 12.6).Oneofthemajorsourcesofoilenteringthemarineenvironmentasacon-sequence of normal shipping operations is the discharge of crude oil and prod-uctsduringtankcleaning,aproblemcausedprimarilybyolder,single-hulled,tankersthatusetanksforbothcargoandballastwater.Quantitativelygreaterthanthis,however,arethelossesarisingfromshipsfueltanksandbilges.As248 Gillian ReynoldsTable 12.5 Inputs of oil to the marine environment, 1990 Source Tonnes Per centMunicipal/industrial 1,175,000 50Transportation 0,564,000 24Atmosphere 0,305,000 13Natural sources 0,258,500 11Offshore production and exploration 0,047,000 2Total 2,350,000Source: Etkin et al. (1998).Table 12.6 Estimates of oil entering the marine environment from shipping, 1989/90Source Discharge (tonnes/year) Discharge(%)Operational discharge of oil cargo from tankers 158,600 27.9 Crude oil: longhaul 45,600 8.0 Crude oil: short haul 20,300 3.6 Product oil: longhaul 20,800 3.7 Product oil: short haul 71,900 12.6Dry docking 4,000 0.7Marine terminals (eg bunker operations) 30,000 5.3Bilge and fuel oil 252,600 44.4 Machinery space bilges 64,400 11.3 Fuel oil sludge 186,800 32.9 Oily ballast from fuel oil tanks 1,400 0.2Accidental spillage 121,000 21.2 Tanker accidents 114,000 20.0 Non-tanker accidents 7,000 1.2Scrapping of ships 2,600 0.5Total 568,800 100Source: IMO (1990).Table12.6demonstrates,thesetwoformsofdischargehavetogethertypicallyaccounted for 4050 per cent of ship-generated oil pollution, made manifest asslicksatsea,oilingofseabirdsandseamammals,andchronicpollutionofbeaches with tar-like deposits. Inevitably there is a geography to these impacts,sincewhiledischargesaresubjecttorestrictionsintermsofdistancefromland5 operational oil pollution tends to be concentrated around the main ship-ping and oil transportation routes.Controls and pollution trendsTherelativeimportanceofaccidentalandotherdischargeswillnaturallyvaryfrom year to year, depending on the severity of tanker accidents. As a long-termtrend, however, signicant reductions in both accidental and operational pollu-tionshouldoccurasareectionofimprovedtechnologiesandregulation.OfparticularimportanceisAnnexItotheInternationalConventionforthePre-vention of Pollution from Ships, MARPOL 73/78. This covers the handling ofoilleakagesandoilywastesintheengineroom,andtheminimisationofdis-charges from oil tanker cargo tanks.Allshipsencounterleakagesfrommachinery,whetherroutinelyorduringmaintenance. This oil will tend to collect in the ships bilges, where it may lie orbetransferredtoabilgewaterholdingtank.InlinewithMARPOLAnnexI,this oily bilge water may then be discharged ashore, for which a charge is gener-allymade,ordischargedtoseathroughanoilywaterseparatororlterwhichtheoreticallyreducestheoil-in-watercontenttoamaximumvalueof15ppm.Larger ships, or those trading in designated special areas such as the Baltic, arealso required to monitor the concentration of oil in water and to cease discharg-ing if the 15 ppm oil-in-water threshold is reached. Additional treatment, suchas the use of ltration to further reduce the oil content of the water discharged,issometimesused,butthisisrareatpresent.Alldischargesaresubjecttorestrictions in terms of distance from land and location outside special, environ-mentally vulnerable, areas.Otheroilywastessuchasthesludgeresultingfromfuelpurication,whichcannot be passed through the oily water separator, will be stored on board in adedicatedtankuntiltheycanbedischargedashore.Inordertoreduceopera-tionaloilpollutionassociatedwiththecleaningofcargo/ballasttanks,proce-dureshavebeendevelopedbytheoilindustryandsubsequentlyincorporatedintointernationallegislation.Theseincludeaparticularsequenceoftankwashing,termedtheloadontopprocedure,whichactstominimisethedis-charge of oil to the sea in tank washings. A system of crude oil washing has alsobeendevelopedwherebycargotanksarewashedwithcargousinghighlycon-trollable tank washing machines. In this process the lighter fraction of the crudeoilactsasasolvent,washingtheheavierfractionsfromthetankwalls.Bythismeans, cargo out-turn can be greatly increased.Despite these measures, assessing the scale of progress remains difcult. Reli-able surveys are few and far between, and evidence can be contradictory. Thus,Operational pollution from shipping 249ithasbeenestimatedthatfollowingtheadoptionofAnnexItoMARPOL,operationaloilpollutionfellbyalmosttwo-thirdsbetween1981and1990fromapproximately1.4millionto0.56milliontonnesayear(Patin2002).However, the annual number of slicks recorded between 1990 and 1998 in theNorth and Baltic Seas areas in which ofcial vigilance is high did not show aconsistent decline (Figure 12.3). For this reason, the recent work of Koops andHuisman(2001),whichhasproducedadvancesinestimatingthevolumeofindividual operational oil discharges, is to be welcomed because of the potentialfor improvements in both data availability and reliability.Waste streamsComposition and environmental impactShipboardwastestreamscomprisesewageorblackwater,domesticwastewater or grey water, oily wastes and garbage. The latter is particularly diverseand can include plastics, packing, glass, crockery, metal, rags, food wastes, cargoresidues, medical waste, ropes, paint, equipment, and so on. As oily wastes frombilges and oil cargo residues have been covered in the previous section, they arenot considered here.Forthepurposesofthischapter,wastesdisposedofashorewillbeassumednot to cause environmental pollution. The environmental impact of wastes dis-charged to sea will be diverse, consistent with their diverse composition and thedisposal route. Although some wastes will be discharged directly to the marineenvironment, particularly outside coastal or various special areas, other wasteswill be actively managed. Sewage and garbage may, for example, be dischargedtoreceptionfacilitiesashore,treatedpriortodischargeorincinerated.Grey250 Gillian Reynolds0.450.400.350.300.250.200.150.100.050.00120010008006004002001990Number of slicksNumber of slicks/flight hours1991 1992 1993 1994 1995 1996 1997 19980Figure 12.3 Annual number of oil slicks from illegal discharges observed by aerial surveil-lance in the North and Baltic Seas. (Source: EEA 2001.)waterisexceptionalinthatitsdischargeisnotrestrictedbyinternationallawand it is most commonly discharged directly to the environment.Somestreamsandespeciallygarbagetendtobeunsightly,butoftenthereareotherimpacts.Discardedropesornetsarehazardoustowildlifeonshoreandatsea.Otheritemsofgarbagepaints,equipmentandmedicalwastes may contain marine pollutants. Sewage and grey water have a high bio-logical oxygen demand (BOD) that depletes receiving waters of oxygen. Sewageandgreywateralsointroducenitrateandphosphateintoreceivingwaters,potentiallycausingrapidalgalgrowthwherewatersarestaticandenclosed.Sewageisnaturallylikelytocarrypathogenicmicrobes,includingE.coli.Thedangerofsomecoliformbacteriaisdemonstratedintherecentdeathsassoci-ated with E. coli food poisoning.Quantication and control of ship-generated wastesQuanticationofship-generatedwastessewage,greywaterandgarbageisreasonablywellcovered.Figuresareavailablefromseveralsourcesonwastesgeneratedperpersonperdayforthevariousshiptypes(NorwegianEnviron-mentalDepartment1994;Schnitler1995;EMARC1998).Wastefactorsincombination with time spent at sea, ship size and type, and crew and passengernumbershavebeenusedtoderiveannualguresforwasteproductionbyshipping on a regional basis (Table 12.7). Some information is also available ontheamountsofwashingagents,onbiologicaloxygendemand(BOD)andnitrogenandphosphorusnutrientsdischargedinsewageand/orgreywaterinthe Baltic Sea (Swedish Shipowners Association 1995).Controlofpollutionfromshipboardwasteshasprimarilybeenachievedthrough international regulation, specically the MARPOL 73/78 Convention,whichaddressespreventionofpollutionbysewageandgarbageintwoofits(currently)sixannexes.Managementofgarbageisgenerallyachievedbycom-paction and storage on board prior to disposal ashore, or by the controlled dis-posal to sea of certain categories of waste in line with restrictions specied in theOperational pollution from shipping 251Table 12.7 EstimatesofsewageandgarbagewastegeneratedannuallybyshippinginEurope Sewage Garbage(000 cu m) (000 tonnes)Eastern Mediterranean 0,0916 12Iberian Peninsula 3,437 44Northern Europe 4,141 51Southern Europe 9,300 112Scandinavia 4,887 61UK/Eire 3,667 45Total 26,348 325Source: EMARC (1998).Convention. Alternatively, waste may be incinerated on board. Control of pol-lution by sewage is achieved either by retention on board and discharge ashore,orbypassagethroughanapprovedsewagetreatmentplant,certiedtomeetinternationalrequirementswithregardtoperformanceandefuentquality.However,whilethereleaseofsewageisnotallowedwithin4nauticalmiles(7.4km)ofthecoast,evenifithasbeencomminutedanddisinfected,outsidethe 12-mile (19-km) limit untreated sewage may be freely discharged to sea.Although,asnotedearlier,thereisnointernationalrequirementtocontrolgrey water discharge, some more environmentally proactive authorities, such asAlaska,areintroducinglocalornationallegislation.Thishasresultedinsomeships,particularlycruiseshipsandmilitaryvessels,takingstepstotreatgreywater on board prior to discharge using systems similar to, or the same as, thoseused for sewage treatment. A development of this approach is that, in additionto waste management systems processing specic wastes, integrated waste man-agementsystemsarebeginningtoemerge.Usingacombinationoftechnolo-gies,thesesystemscanprocessmostwastesproducedonboardincludingsewage and grey water; bilge water; metal, glass, paper, plastics and food waste;and clinical and sanitary wastes (Smith et al. 2002).ConclusionThis chapter has underlined the extent of the range of environmental problemsassociated with day-to-day shipping operations that affect both the atmosphereandthemarineenvironment.Ithasalsoindicatedrelationshipsbetweentheseproblemsandtheotherdominantthemesinthisvolume:globalisationandtechnologicalchange.Shipsworkingatthelocalandregionalscalesnaturallycontributetoenvironmentalpollutionatlocal,regionaland,indeed,globallevels. But in addition there are the problems related to the increasing globalisa-tionoftrade,suchasthepotentialfornon-nativeorganismstobetransportedmany thousands of miles in ships ballast water. These global impacts are in turnlinkedwiththenecessityforenvironmentalpollutionproducedbyshipstoberegulated internationally.Regulationcan,however,rarelyachieveaninstantaneoussolution.Instead,progress is usually a much more incremental process, brought about by pressureondifferentsectorsatdifferentpointsintimeandbydifferentinstitutions,oftenasnewprioritiescometobeappreciated.ThisiswellillustratedbyAlaskasrecentunilateraldecisiontoimposelocalcontrolsongreywaterdis-charge into the states highly sensitive waters while geographically more wide-spread legislation is not yet being considered by the international community.Signicantleadtimesarealsointimatelylinkedwithtechnologicalfactors.Althoughinsomeinstanceslegislationcanlimitpollutioneffectivelyintheshortterm,technologicaladvancesarefrequentlyrequiredbeforecontrolbecomes a realistic proposition for example, to reduce emissions to the atmo-sphereorprocesswastes.Inevitably,theseadvancestaketime.Moreover,evenwhen appropriate technologies become available, progress may still be retarded252 Gillian Reynoldsbythetechnicaldifculties,and/orcost,ofapplyingthemtoexistingvessels.This dictates the necessity for measures such as phase-out periods and grandfa-therclauses,wherebylegislationisnotappliedtoexistingships.Despitesuchobstacles,however,thereisnodoubtthattechnologicalchangehasakeyroleto play in the reduction of vessel pollution, a role complementing other techno-logical advances such as those reviewed in Part II of this book aimed primar-ily at economic efciency.AcknowledgementManyofthedataonemissionanddischargeestimatesquotedinthischapterwere compiled in the context of the Technologies for Reduced EnvironmentalImpact from Ships (TRESHIP) thematic network, under contract to DG-XII oftheEuropeanCommission.ThecontributionofthenetworkparticipantsandcolleaguesatLloydsRegistertotheinformationreportedhereisgratefullyacknowledged.Notes1 Signicantconcentrationsofpolychlorinatedcompoundsareonlylikelytobeassoci-ated with isolated incidents of chemical contamination of fuels.2 This variation can be attributed to such factors as the use of different base years, calcu-lationmethodologies,emissionfactors,eetsegmentsandgeographicallimitsforthedifferent inventories.3 The application of fuel cell technology is much further advanced for road vehicles.4 VOCemissionsduringcoatingapplicationcanalsobeofsignicance,thoughthisrelates to air, rather than water, pollution.5 No discharge is allowed within 50 nautical miles (92.6km) of land or within a specialarea.Beyond50nauticalmiles,dischargeispermittedwhenatankerisenroute,subjecttorateandvolumerestrictions.SpecialareascurrentlyincludetheMediter-ranean, the Black, Baltic and Red Seas, the Gulf area, the Gulf of Aden, and AntarcticandNorth-WestEuropeanwaters.ThelattercomprisetheNorth,IrishandCelticSeas, the English Channel and western approaches, and the north-east Atlantic imme-diately west of Ireland.ReferencesAlexandersson,A.,Flodstrm,E.,berg,R.andStlberg,P.(1993)ExhaustGasEmis-sion from Sea Transportation, TFB report 1993/1, Goteborg: MariTerm AB.AspenPublishersInc.(weekly)InternationalOilSpillStatistics,OilSpillIntelligenceReport,NewYork:AspenPublishersInc.,availableatwww.aspenpublishers.com(accessed 8 January 2004).Australian Bureau of Statistics (1997) 4605.0 Australian Transport and the Environment,available at www.abs.gov.au (accessed 8 January 2004).BMT (2000) Study on the Economic, Legal, Environmental and Practical Implications of aEuropean Union System to Reduce Ship Emissions of SO2and NOx, European Commis-sionContractB43040/98/000839/MAR/B1,availableat:www.europa.eu.int/comm/environment/enveco/studies2.htm#27 (accessed 8 January 2004).Operational pollution from shipping 253Bremnes, P.K. and Melhus, . 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