HYDROCARBONS AND BACTERIAL ACTIVITY IN MANGROVESEDIMENTS FROM GUANABARA BAY, BRAZIL

摘要

In this study, a very extended law protected mangrove area in the Easternpart of the Guanabara Bay was screened for petroleum hydrocarbons (PAHs) and bacterialactivity. The aim was to understand the processes that control oil contamination inthe mangrove sediments and if there is a relationship between this contamination andbacterial activity. Surface sediment samples were collected from 23 stations covering themangrove interface with the bay. The parameter pH, Eh, salinity, and temperature weremeasured in situ. The sediments were immediately analyzed for bacterial activity thatincludes: 1) electron transport system activity (ETSA); 2) activity of esterase enzyme(EST); and 3) bacterial biomass. Analyses of the PAHs were performed by UV- visiblespectrofluorescence and total organic carbon was analyzed by titration. The results showthat although the amounts of hydrocarbons loaded into the bay are considerable,Guapimirim mangrove presents low concentrations. Although the indicators of bacterialactivity (ETSA and EST) can be considered extremely elevated, they did not show anysignificant correlation with PAHs (p<0.05). The bacterial biomass is correlated withPAHs (p<0.05). It can be drawn from the results that although the bacterial activity iselevated, the presence of important amounts of organic matter constitutes a significantsource of food for bacteria that consume very little PAHs.