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Samples of organic aerosol were collected in Santiago de Chile. An activated-charcoal diffusion denuder was used to strip out organic vapors prior to particle collection. Both polynuclear aromatic hydrocarbons (PAHs) and aliphatic hydrocarbons were determined using gas chromatography/mass spectrometry (GC/MS). Organic particle sources were resolved using both concentration diagnostic ratios and multivariate methods such as hierarchical cluster analysis (HCA) and factor analysis (FA). Four factors were identified based on the loadings of PAHs and n-alkanes and were attributed to the following sources: (1) high-temperature combustion of fuels; (2) fugitive emissions from oil residues; (3) biogenic sources; and (4) unburned fuels. Multilinear regression (MLR) analysis was used to determine emission profiles and contributions of the sources. The reconstructed concentrations of particle phase aliphatic and polynuclear aromatic hydrocarbons were in good agreement (R2 > 0.70) with those measured in Santiago de Chile.

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The chemical and physical (water content) changes in sediment profiles beneath a n d around fish farm cages were investigated on a seasonal basis In Cephalonia Bay, Greece, a relatively enclosed marine area wlth weak currents and silty substrate. The surface concentrations and the vertical distribution of the sedimentary variables studied (organic matter, organic carbonhitrogen, chlorophyll, phaeopigments, water content and total phosphorus) varied substantially with distance from the cages and with season The black-coloured top layer (farm sediment) showed high concentrations of organic matter, phaeopigments and total phosphorus as well as high water content while the compact subsurface layer had concentrations close to (or lower than) those at the control site. The thickness of the farm sediment layer under the cages varied with season, while in all seasons it decreased rapidly with increasing distance from the cages.

After the removal of fish cages at an intensive aquaculture site, the sedimentary environment was monitored over 23 mo for redox potential, total organic carbon and nitrogen, total phosphorus, algal pigments and macrofauna. Three sampling stations were established: one under the previous location of the cages (R-0), a second one (R-10) at 10 m distance from the edge of the cages and a control site (R-c) at > l km distance. At both stations near the farming site the sediment was initially found to be anoxic and overlain by a highly organic black layer. Most geochemical variables at Stn R-10 attained values close to those at Stn R-c within 11 mo. Large fluctuations In the values of most variables were observed at Stn K-0 over the 23 mo, indicating that the environment had not fully recovered before the end of the observations. Similar results were obtained from the macrofaunal analysis, which revealed that after 2 3 mo a high proportion of benthic fauna at Stn R-0 was still composed of opportunistic species; abundance biomass and species composition showed marked successive changes in the direction of succession. This regression was attributed to a secondary disturbance due to a benthic algal bloom, caused by the seasonal release of nutrients from the farm sediment. It is concluded that the recovery process of heavily enriched benthos in a dynamic coastal environment is subject to the influence of different factors, resulting in progress and regression, and therefore the succession model proposed by Pearson & Rosenberg (1978; Oceanogr Mar Biol Annu Rev 161229-31 1) may not be applicable in the early stages of succession. KEY WORDS: Fish farms. Aquaculture. Benthic recovery. Redox. Organic carbon. Nitrogen. Phosphorus. Pigments. Macrofaunal succession. Abundance-Biomass Comparison curves O Inter-Research 1999 Resale of full article not permitted

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