Org. Geochem. Vol. 6, pp. 237-248, 1984 I} 146-638()/84 $113. ~ Ill+0.011 Printed in Great Britain. All rights reserved Cop}right © 1984 Pergamon Press Ltd Dissolved, particulate and sedimentary hydrocarbons in a deltaic environment J. ALBAIGl~S l, J. GRIMALT I, J. M. BAYONA I, R. RISEBROUGH 2, B. DE LAPPE 2 and W. WALKER II 2 ~Institute of Bio-Organic Chemistry (CSIC), Jordi Girona Salgado, Barcclona-34, Spain -'Bodega Marine Laboratory, Universitv of California, Bodega Bay, CA 94923, U.S.A. Abstract--A study of biolipid indicators in the Ebro Delta (Spain) involvingthe analysis by cornputcrizcd GC-MS of dissolved, particulate and sedimentary hydrocarbons (saturated and unsaturated) was carried out. Thrcc differcnt depositional environments were considered, namely the river mouth, the open sea and the delta bays. The water column was sampled with a recently designed filtering and extraction system bascd on a Teflon impeller pump which passed water through a glass fibre filter and a Teflon cohtmn packed with polyurethane foam plugs, where respectively particulate and dissolved material was collected. The dccoupling of lipids betwccn the different marine compartments was closely dependent on their sources and exhibited seasonal and spatial variations reflecting environmental conditions. Anthropogenic HCs (UCM. 17a(H),21~(H) hopanes) were mainly concentrated in the dissolved phase. AIIochthonous continental inputs (n-CzT-n-C~t alkanes and alkenes) were recognized in particulates collccted in the opcn sea, whereas autochthonous planktonic inputs (n-C~,. n-Cr. pristenes, HEH'I were idcntilicd mainly in the bays. Bacterial activity was recognized by the presence of 1713(H).2l[5(H) hopanes and hopcnes. A bioconversion of petroleum short chain n-alkanes was observed during spring in the ba\s. New di- and tri-unsaturatcd HCs related to C_,,, and C2~ muhibranched isoprcnoids were identilicd in particulates, pointing to planktonic and metabolic or diagenetic origins. A series of scsquitcrpcnoid cvchmlkcncs (cadinene derivatives) not previously reported in the marine environment affords evidence of inputs of higher plant resins. The corresponding aromatic derivatives were found in the sediments together with abictane and pimarane aromatized HCs. The results presented illustrate that thc study_of lipids m dissolved and particulate phases of the marine environment may provide a better understandine of this cnvironment in terms of both sources of organic matter, transport routes and depositional conditions. Key words: alkenes, dissolved and particulate hydrocarbons, Ebro Delta, marine hydrocarbons, marine sediments, sesquiterpenes INTRODUCTION Recent studies carried out by several authors in different marine regions (Boehm, 1980: Goutx and Saliot, 1980; Boussuge et al., 198(I) have provided evidence of the decoupling of the organic matter with respect to the source, in the dissolved, particulate, surface microlayer and sediment interstitial phases. The precise characterization of these phases not only may provide useful information about the origins but also about the transport paths and fates of organic compounds in the sea, questions which are of con- siderable interest in the study of marine biogeoche- mical cycles. In this respect it is apparent, for example, that through the determination of particu- late compounds it is possible to gain some insight into the processes governing the sedimentation of various chemical species (Honjo, 1978; Spencer et al., 1978; Brewer et al., 1980), to make estimations of fluxes of specific constituents in the water column to the sea floor (Crisp et al., 1979; Burns and Villeneuve, 1983: DeBaar et al., 1983) and to obtain information about diagenetic transformations prior to deposition (Gagosian et al., 1982). Estuarine or deltaic systems are of special interest because they constitute areas of transport and de- position of continental inputs into the coastal en- vironments (Kullenberg, 1983). The dynamics of fine-grained particles and particle-associations in the zones of mixing waters are complex (Soutar et al., 1977: Olsen et al., 1982) and play a significant role in the understanding of the transfer processes from those compartments to the sea. In spite of this, the knowledge of dissolved and particulate organic mat- ter in these systems is rather limited. In the framework of a general investigation on biolipid indicators in deltaic environments (Grimalt, 1983), dissolved, particulate and sedimentary alkanes and alkenes have been determined in the Ebro Delta (Spain) (Fig. 1). Three different deposi- tional environments were considered, namely the river mouth, the open sea and the delta estuaries. Sampling has been carried out using a recently designed water extraction system (DeLappe et al., 1983) which involves the use of polyurethane foam as adsorbent. EXPERIMENTAL Sampling Water and sediment sampling was carried out from R/V Invincible (Bodega Bay Institute). A non- contaminating Teflon impeller pump (Jupiter, Fluorocarbon Corp.) pumped seawater from a depth 237