Characterization and distribution of polycyclic aromatic hydrocarbons in sediments from Suru Mangrove, Guanabara Bay, Rio de Janeiro, Brazil

摘要

Four sediment cores were collected in Suru Mangrove. Cores 0.30-m long were sliced into small cores corresponding to 00.03, 0.050.10, 0.100.15, 0.150.20, 0.200.25, and 0.250.30-m depths. Polycyclic aromatic hydrocarbons, total organic carbon (TOC), and total sulfur (TS) were determined. Total organic carbon varied between 0.8% and 7.8%, with mean values varying according to sampling location (5.2% for core 1, 3.2% for core 2, 4.2% for core 3, and 2.7% for core 4). Total sulfur also varied in the studied cores with a mean ± standard deviation of 1.1% ± 0.7%. The lowest value (0.01%) was found in core 2 (0.100.15 m), and the largest one (2.6%) was observed in core 4 (0.25030 m). The TOC/TS ratio indicated that most sediments showed reducing characteristics, except for four samples (core 1 of 0.100.15 m and 0.250.30 m, and core 2 of 00.03 m and 0.050.10 m). Total PAH concentrations varied between 4.4 and 1387 g g ~(-1), indicating a local and restricted contamination of parts of the studied area. The highest percentages for total and carcinogenic PAHs and toxic equivalent factors were found in the sediment from core 1 from Suru Mangrove, with a predominance of benzo[k]fluoranthene, benzo[a]pyrene, and naphthalene. In cores 3 and 4, collected closer to Guanabara Bay, benzo[a]anthracene and benzo[a]pyrene were also found. The sediment in Suru Mangrove is functioning as a reservoir of compounds that are carcinogenic to the fauna and flora of the mangrove itself, and to the adjacent waters of Guanabara Bay.