Abstract This study evaluated the bioavailability of polycyclic aromatic hydrocarbons (PAHs) in Santos Bay (SB) and the adjacent Santos Continental Shelf (SCS) in Brazil. Biliary metabolites were measured in several fish species to establish a baseline for future monitoring programs. Bile samples from different species of fish were collected monthly from July to December 2005 in SB, and in August 2005 and February 2006 on SCS. Metabolite concentrations were determined using high-performance liquid chromatography with fluorescence detectors. Naphthalene, phenanthrene, and benzo[a]pyrene metabolite concentrations ranged from 24 to 810 µg g -1 of bile, 1.8 to 68 µg g -1 of bile, and below the limit of quantitation to 1.3 µg g -1 of bile, respectively. Despite its high concentrations, the levels of naphthalene metabolites were in regions of low-contamination, while benzo[a]pyrene metabolite were in the same range as those reported in moderately contaminated areas, which may indicate pyrolytic contamination by PAHs. No significant differences in the metabolite concentrations were found between the SB and the SCS samples or during the periods of collection. Future studies with a single biomonitoring species should be conducted, considering age, sex, and feeding condition of the individuals. The metabolite data presented in this study is an important baseline information for this urbanized region, which hosts several sources of contaminants. PAHs (PAHs (SB (SCS Brazil programs 200 highperformance performance detectors Naphthalene phenanthrene benzoapyrene benzo pyrene 2 81 1 - bile 18 8 1. 6 13 3 respectively lowcontamination, lowcontamination low contamination, low-contamination areas collection conducted age sex individuals region contaminants 20

ORGANIC MATTER SOURCES TO THE SUPERFICIAL SEDIMENT OF THE ITAPICURU RIVER ESTUARY (BAHIA - BRAZIL). The present study evaluated the sources of organic matter (O.M.) in the Itapicuru River estuary (IRE), which is in an environmentally protected area surrounded by the Atlantic Rainforest in the northeast of Brazil. Eleven sediment samples were collected along the study area. Total organic carbon (TOC) and the δ13C values were determined using an elemental analyzer coupled with an isotope ratio mass spectrometer. The n-alkanes composition was evaluated through gas chromatography coupled to a flame ionization detector. TOC and total n-alkanes concentrations ranged, respectively, from not detected to 0.72%, and from lower the limit of detection to 5024 ng g-1. There was a significant concentration of n-C22 and n-C24 in some samples showing bacterial production and recycling of O.M. Values of δ13C ranged from -27.6 to -21.9‰. Carbon preference index, terrestrial-aquatic ratio, aquatic production index, average chain length, and the ratio between n-C29 and n-C31 values ranged, respectively, from 1.42 to 4.11; 2.82 to 9.40; 0.00 to 0.25; 27.7 to 29.9; and 0.27 to 0.43. These results show that concentrations of O.M. to IRE are low, and its main source is C3 plants, such as those from mangroves. There is also the contribution of macrophytes. BAHIA BRAZIL. BRAZIL . BRAZIL) OM O M (O.M. IRE, , (IRE) Brazil (TOC δC δ C spectrometer nalkanes n alkanes detector respectively 072 0 72 0.72% 502 g1. g1 g 1. 1 g-1 nC22 nC C22 n-C2 nC24 C24 O.M 27.6 276 27 6 -27. 21.9‰. 219 21 9 -21.9‰ index terrestrialaquatic terrestrial length nC29 C29 nC31 C31 n-C3 142 42 1.4 4.11 411 4 11 282 2 82 2.8 9.40 940 40 000 00 0.0 0.25 025 25 277 7 27. 29.9 299 29 027 0.2 043 43 0.43 low plants mangroves macrophytes (O.M (IRE 07 0.72 50 g- nC2 C2 n-C -27 21.9‰ -21.9 nC3 14 4.1 41 28 8 2. 9.4 94 0. 02 29. 04 0.4 0.7 5 -2 21.9 -21. 4. 9. 21. -21