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l <br /> gin•-ts � <br /> Nacural ecosystems have corLsZderaale exposure co petroleum <br /> 'iydrocz=ons f_cta nazursl emissions. icc-denral contaatztazi.on t`trouan <br /> oil spills and srara¢e cs^y lea,L�, o;d dali:grata 'application to 1ant <br /> t u to disaosal acciritias such as land-car=zag; therefore <br /> • their <br /> biodegra�ttan is of enviror_an=.L L sort::ice. Numerous authors have <br /> observed ch biodegraoar:ion of perro'lau= hydrocarbons. and.2255sever.2Xal ~ <br /> extensive reviews and reports ' are available (1846,2252 <br /> x2531- An exrMaszve and diverse grcun of pezreleum hydrocarbon. <br /> degrading bacteria and funq_i are widely disc—bused in the emrirorarsenc. <br /> -kithnugra the microbioza of =ost non Cha sails include runny <br /> naturally occurring hydrocarbon-degrading popular-tons. the. addition of <br /> Petroleum saLeccively enriches chat sector able to adapt and iaei <br /> Cho new substrate. Ocher iize environmental faccors shown to have a major <br /> effect ora biodegradability are availability of oxygen and �modaraca <br /> or _. <br /> cempaxaturea- The resdar is referred to Chapcar 64 for a more daeailed <br /> SuMMary of the biodegradation of petroleum hydrocarbons. <br /> The aualicaclve hvdrocarzon content of pecroleum mixtures <br /> rLargel _ <br /> ecermines their degracabiiicv. In general. micraorgantsms exhibity <br /> decreasing abilicv co de3raae aLiphattc hydrocarbons with increasing � <br /> chain Length; aromactcs are generally more rapidly biodegraded than <br /> alkanes • The composition of diesel oil suggests chat some of the <br /> aromatic species '-rill be biodegradable: biodegradation of the highs <br /> =olecular seighc aromatics etipecred to he presenc in residual oils will <br /> be slower (2339) . <br /> In summary. 1 <br /> biodegradation of the petroleum hydrocarbons <br /> comprising diesel and fuel oils may occur under conditions Favorable <br /> for microbial activity <br /> the and when Fuel components are freely available to <br /> rmicroorgantsms, Degradation may be <br /> environments Limited and/or slow in <br /> environmentsLich few degrading organises , low pH, lav temperatures. <br /> Ona high salinxc•r (e • g- • arct_a environmeencs) . Cc should be mentioned <br /> MC! Valker ec a1 . (2257) stale chat even under optimum conditions. <br /> .ocal and complete bioaegracacion is not expeccaa ca occur except <br /> possibly over an extremely long time Deride- ... <br /> 66.1.3 Pri=ry Rouces of Exposure from Soil/Ground-Lacer Systems <br /> The above discussion of face achuays su <br /> have tow %- p g$escs chat pure fuel DLLs <br /> spar pressure but that chef; components -ary in chair � <br /> volacilzcr from vacer• The components are strongly or t-ery scronly <br /> soroed co soil. `-y <br /> The poi�cvclzc aromatic hvdrocarbons in iuel oils <br /> a moderate or high ipotethential for biOaccUmuiacion• •.chile d <br /> longer-cnan aliphatic comaounas have low potential <br /> 'biaacctUmulscion. These °-ate characzerisc.cs suggest chat thevarious <br /> for <br /> or <br /> components may have SGRiewnac different potential exposure oachuays . <br /> Volatilization of fuel oils f.o:m a dis <br /> not be expected to result pasal site or spill would <br /> writers or residents in the s ea. Gravic-.• uouldlaand totion car.exposures bulk <br /> .tun t��es or `h$ oil town cow-arcs .-Re •_acer table leaving only a <br /> ? r � <br /> c� <br /> 6/87 <br />