Natural and anthropogenic sterols inputs in surface sediments of Patos Lagoon, Brazil

Abstract

A Lagoa dos Patos (RS), considerada a maior lagoa costeira do mundo, tem sido afetada por diversas atividades antrópicas. Um risco de contaminação por esgoto ocorre devido ao estabelecimento de mais de 2 milhões de habitantes ao longo da bacia de drenagem desta região. Amostras de sedimentos foram coletadas e analisadas por CG-EM. Dez diferentes esteróis, incluindo coprostanol e epicoprostanol (fecais), e cetonas foram identificados e quantificados. A maior concentração de coprostanol foi encontrada próximo à cidade de Porto Alegre (1.423 ng g -1 ). Nos demais pontos, a concentração variou desde o limite de detecção até 91,78 ng g -1 .As maiores concentrações foram encontradas próximo à descarga de esgotos e os níveis diminuíram com o aumento da distância desde as fontes. As razões isoméricas 5β / (5β+5α) indicaram sedimentos contaminados próximo a Porto Alegre. A razão epicoprostanol/coprostanol mostrou valores característicos do aporte de esgoto sem tratamento ao longo da Lagoa dos Patos.The Patos Lagoon, the largest coastal lagoon in the world, has long been receiving considerable anthropogenic input resulting from urban, rural and industrial activities. Thus, sewage contamination possibly originating from the more than 2 million inhabitants living within its drainage basin is examined in this study. Sediment samples collected from various points along the Lagoon were extracted, purified and analysed by GC-MS. Ten different sterols and ketones, including coprostanol and epicoprostanol, were identified and quantified. The highest coprostanol concentration was found near Porto Alegre City (1,423 ng g -1 dry wt.), whilst most sediment levels ranged between < DOL and 91.78 ng g -1 . The highest concentrations were found at those three sites located closest to domestic outfalls though levels tended to decrease with distance from the sources. The 5β/(5β+5α) isomeric ratios indicated sewagecontaminated sediments near Porto Alegre City, while the epicoprostanol/coprostanol ratio showed values characteristic of untreated sewage input.

Assessment of historical fecal contamination in Curitiba, Brazil, in the last 400 years using fecal sterols

“…Since the first human settlements, the discharge of sewage, especially untreated sewage, has been primarily responsible for the degradation of surface waters and aquatic environments, as well as of groundwater (Martins, 2007). The use of micro-organisms (e.g., Escherichia coli) to study and confirm domestic sewage contamination in water samples and sediments is limited due to a lack of specificity, light sensitivity (Chevremont et al, 2012), short lifetime, and little resistance to temperature variation (Bebianno and Mudge, 1997;Martins, 2007), making it impossible to study past contaminations.…”

“…The use of micro-organisms (e.g., Escherichia coli) to study and confirm domestic sewage contamination in water samples and sediments is limited due to a lack of specificity, light sensitivity (Chevremont et al, 2012), short lifetime, and little resistance to temperature variation (Bebianno and Mudge, 1997;Martins, 2007), making it impossible to study past contaminations.…”

Validation of an Analytical Method for Geochemical Organic Markers Determination in Marine Sediments

“…Colest-5-en-3β-ol foi o esterol mais abundante neste testemunho, resultado verificado em outros estudos na região antártica, 22,[36][37][38] uma vez que esse composto é abundante em sistemas marinhos devido à sua distribuição no plâncton marinho. 39,40 Além dessa fonte, animais superiores como aves e mamíferos marinhos também são uma importante fonte desse composto para os sedimentos na região antártica. 41 A distribuição dos esteróis ressalta a contribuição de organismos do fito e do zooplâncton, com predomínio do colest-5-en-3β-ol, e com a presença de 24-etilcolest-5-en-3β-ol, 24-etilcolest-5,22E-dien-3β-ol, 24-metilcolest-5,22E-dien-3β-ol e 4α,23,24-trimetil-5α-colesta-22E-en-3β-ol indicando que cianobactérias, diatomáceas, algas primnesiófitas e dinoflagelados compõem os principais contribuintes da matéria orgânica na região.…”

Vertical profiles of bacterial-sewage derived biomarkers in marine sediment

“…Coprostanol and epi-coprostanol are compounds of sterol which are mainly used as sewage tracers. Coprostanol is a product of cholesterol microbial reduction in the digestive tracts of human and higher vertebrates [8], while epi-coprostanol is the isomer of coprostanol which is formed during the microbial digestion process from coprostanol [9]. These groups of compounds were chosen because they are related to each other because of the presence of bacterial colonies together with the sewage or when there are presence of organic matter that needs to be decomposed [8,10].…”