Abstract Pockmarks are circular or elliptical structures formed at the seabed by the expulsion of gas from the subsurface. They are widely distributed along the continental margin off southeastern Brazil and can be over a kilometer wide and 100 meters deep. However, studies concerning the organic characteristics of these pockmark areas are scarce. This study sought to evaluate the organic composition of the sedimentary matter in pockmark areas located in the continental slope region of the southern Brazilian coast. Hydrocarbons, sterols, long-chain alcohols, stable isotopes of C and N, total organic carbon, and total nitrogen were assessed to provide an organic molecular characterization of the pockmarks located in the Southwestern Atlantic Ocean. These compounds did not reflect the organic characteristics of the scape of fluids that generate pockmark structures.

For the evaluation of PAH extraction techniques in adipose and liver tissues of marine tetrapod, samples of some species (Pontoporia blainvillei, Chelonia mydas, Thalassarche melanophris, and Balaenoptera brydei) were spiked with PAH standards and extracted using soxhlet system and microwave oven. The results of both extraction techniques for the two different tissues of the four species of tetrapod were within the quality assurance and quality control criteria, that means both extraction techniques produced acceptable recoveries for surrogate and spiked compounds added to the sample tissues. Although both techniques of extraction met quality criteria and were considered suitable for extraction of marine tetrapod tissues, the soxhlet system produced a higher recovery of the spiked compounds and a lower standard deviation between the replicates than the microwave extraction; therefore the soxhlet system was considered the more efficient extraction method for PAH. The evaluation of liver and adipose tissue PAH accumulation, as well as the influence of tissue heterogeneity, was impaired as the concentrations of PAHs in almost all samples were lower than the detection limits of the analytical method.

Resumo Bifenilas policloradas (PCBs) e pesticidas organoclorados (OCPs) são compostos orgânicos sintéticos que causam efeitos negativos em organismos aquáticos, eventualmente alterando o funcionamento de ecossistemas com consequências locais para o ciclo do carbono. O presente estudo investigou PCBs e OCPs em sedimentos superficiais de dois estuários com distintos históricos de ocupação na costa de Pernambuco. Os pesticidas HCB, aldrin, dieldrin, isodrin, mirex, metoxicloro, endosulfans, HCHs e clordanos não foram encontrados acima de seus limites de detecção nas amostras. As concentrações médias de PCBs na Bacia do Pina e no Estuário de Suape foram 4,37 e 0,94 ng g-1 peso seco (ps), respectivamente. Para DDTs, as concentrações médias nesses estuários foram 5,24 e 0,42 ng g-1 ps, respectivamente. Não foram encontradas correlações significativas entre a fração lamosa do sedimento e os contaminantes (PCBs e DDTs) na Bacia do Pina. Em contrapartida, os PCBs foram encontrados associados à lama no Estuário de Suape. A maior contaminação na Bacia do Pina é condizente com a área historicamente urbanizada e densamente povoada da cidade do Recife. A composição de DDTs no sedimento de ambos os estuários indica uso antigo desse pesticida. Os níveis de DDTs em diversos pontos da Bacia do Pina podem ocasionalmente desencadear efeitos negativos na biota local. Por outro lado, os baixos níveis de PCBs encontrados no Estuário de Suape - uma área que passa por recente processo de industrialização - sugerem que novos complexos industriais tendem a causar baixo impacto em termos de poluentes orgânicos persistentes herdados de práticas antigas.

Abstract Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are man-made organic chemicals that have adverse effects on aquatic organisms, sometimes altering ecosystem functioning with potential consequences for the coastal carbon cycle. This study assessed PCBs and OCPs in surface sediments of two estuaries with distinct historical land use on the coast of Pernambuco, northeastern Brazil. OCPs such as HCB, aldrin, dieldrin, isodrin, mirex, methoxychlor, endosulfans (α- and β-isomers), HCHs (α-, β-, γ- and δ-isomers) and chlordane-related compounds were below their respective limits of detection in all samples. Mean levels of PCBs in Pina Sound and Suape Estuary were 4.37 and 0.94 ng g-1 dry weight (dw), respectively. Average concentrations of DDTs in those same estuaries were 5.24 and 0.42 ng g-1 dw, respectively. No significant correlations were found between mud and contaminants (either PCBs or DDTs) at Pina Sound. In contrast, PCBs were significantly associated with mud at Suape Estuary. The greater contamination found at Pina Sound is consistent with land use of the urban, densely populated city of Recife. Residues of DDTs found in sediments of both estuaries reflect past local usage. Occasional adverse biological effects may be expected due to the levels of DDTs at several sites in Pina Sound. Lower levels of chemicals such as PCBs in the newly industrialized Suape Estuary suggest that a similarly low impact of legacy pollutants may be expected for future industrial enterprises around the world.