Environmental impact of the largest petroleum terminal in SE Brazil: A multiproxy analysis based on sediment geochemistry and living benthic foraminifera

Abstract

The Dutos e Terminais do Centro Sul (DTCS) is one of the largest petroleum terminals of the South America located in the São Sebastião Channel (SSC) on the southeastern Brazilian coast. The aims of this study were to compare the sediment quality near the DTCS with that of several sites in the SSC region including the Araçá (AR) domestic sewage outfall and to assess the efficiency of the DTCS wastewater treatment plant. To achieve these goals, textural, geochemical, and living benthic foraminifera results were analyzed for the DTCS, AR, and SSC regions. Sediments in the DTCS area were silty with high concentrations of total organic carbon (1.7–2.4%), total nitrogen (0.2–0.3%), total sulfur (0.4–0.6%), and total (0.12–0.18%) and inorganic phosphorous (0.07–0.11%). These values were higher than those in sediments collected in the SSC and Araçá regions. The sediments’ concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in the SSC and AR regions were lower than their corresponding probable effect levels (PELs). However, sediments near the DTCS were enriched with As, Cu, and Ni, whose concentrations exceeded their corresponding threshold effect levels (TELs). Around the DTCS outfall diffusers, living foraminiferal densities and diversities were lower than those for the other areas studied. In the DTCS area, it was necessary to search 50 to 190 cm3 of sediment to find 100 live specimens. In the SSC and Araçá areas, a maximum of 40 cm3 of sediment was enough to locate 100 live specimens. The lower density and diversity of living foraminifera around the DTCS than around the other areas illustrates the impact of the environmental stress caused by the presence of pollutants. These results indicate that the wastewater treatment plant efficiency is low and its discharge of pollutants from petrochemical waste liquids affects the benthic fauna around the DTCS in a potentially harmful manner.

Response of Benthic Foraminifera to Environmental Variability: Importance of Benthic Foraminifera in Monitoring Studies

“…Surface sediment samples were collected for the following analyses: (i) grain size analyses; (ii) geochemical analyses; and (iii) determination of living benthic foraminifera. Textural, trace elements, and foraminifera data from TB, AR, and SSC areas were previously studied by Teodoro et al [46,53], which described in detail the methods of sedimentological and geochemical analysis.…”

“…Canonical correspondence analysis (CCA) was used to investigate the relationship between foraminifera and sedimentological variables of the three areas: TEBAR, Araçá, and São Sebastião Channel (see details in [53]). The Monte Carlo permutation test (999 permutations) was used to assess the statistical significance of the correlations (at p < 0.05 and p < 0.01).…”

“…When they occur separately, it is often in environments with different natural conditions, which makes comparison problematic. São Sebastião Channel (SSC) is an open area where industrial and domestic effluents are separately disposed, but under similar natural conditions, offering the opportunity to compare their impact on benthic biota [53].…”

“…Among these, the central region of the channel has the largest petroliferous terminals of South America, "Dutos e Terminais Centro Sul" (DTCS) of PETROBRAS. According to Duleba et al [53], the DTCS generates two types of liquid effluents. The first type consists mostly of water, separated from oil by density during transportation from drilling platforms in the oil tankers; the second type consists of rainwater and industrial water from the DTCS, contaminated by oil.…”

Petrochemical Wastewater and Produced Water

“…A multiproxy analysis based on sediment geochemistry and living benthic foraminifera was carried out to evaluate the environmental impact of the largest petroleum terminal in SE Brazil (Duleba et al, 2018). The wastewater treatment plant efficiency was found to be low and its discharge of pollutants from petrochemical waste liquids affected the benthic fauna in a potentially harmful manner.…”