ANNUAL ACTIVITY REPORT - Instituto de Biologia da UFRJ

and associated to natural contribution. Values observed forthese compounds are 0.01 to 0.02 μg.g –1 (coprostanol) and0.01 to 0.03 μg.g –1 (epicoprostanol) (Table 1).Concentrations of coprostanone also can be attributed tonatural contribution, since it is assigned to marine mammalfeces, such as fecal sterols. Higher values (>0.50 μg.g –1 ) inthe most recent layers are found at REF (0.69 – 3.62 μg.g –1 )and PTH (0.32 – 0.52 μg.g –1 ). Coprostanone from sewageinput in these sites was not expected as none of the stationslocated in the two inlets discharge sewage in the region(Martins et al., 2002).In order to minimize the ambiguity of sources for thesecompounds, the use of numerical ratio involving fecalsterols are important tools in the differentiation of thesources of fecal organic matter. Venkatesan and Santiago(1989) have proposed specific indexes as the ratio betweenthe concentration of coprostanol and epicoprostanol,as a way to distinguish the places studied in relation tothe contribution of fecal sterols from human or marinemammals, specifically to the Antarctic environment. Valuesbelow 2.50 may indicate natural contribution, while valuesabove 2.50 are strongly related to sewage. REF did not showvalues exceeding 2.50 in any section (1.67 ± 0.71), suggestingthat the main source of sterols are marine mammals. Thesame results occurred to the sediment cores from EzcurraInlet (1.24 ± 0.57 – PTH; and 0.86 ± 0.40 – BAR) (Table 1).The results of this ratio showed that the source ofsedimentary fecal steroids is from natural contributions. Atwhich point, background values can be determined, whichare useful to evaluate a hypothetical sewage discharge in theseregions. In Martel Inlet, the background values related tonatural sources of fecal sterols (coprostanol+epicoprostanol)have been established as 0.19 μg.g −1 (Montone et al., 2010).Considering the mean value obtained for each threecores, the background values to the sum of coprostanoland epicoprostanol, the purpose of this study are:(0.06 ± 0.02) μg.g −1 (REF), (0.04 ± 0.03) μg.g −1 (PTH) and(0.03 ± 0.01) μg.g −1 (BAR). Coprostanone did not presenta regular distribution according to the depth, showingincreased concentrations in the top layers and low levelsin the bottom cores, in that it is difficult to establishbackground values to this compound. In this case, it isnecessary to consider the degradation processes in topsections and unusual inputs in specific layers of REF andPTH.ConclusionsConcentrations of fecal sterols (coprostanol andepicoprostanol) in all locations studied were