Distribution and source apportionment of hydrocarbons in sediments of oil-producing continental margin: a fuzzy logic approach.

Investigation were carried out targeting distribution and source apportioning of hydrocarbons in surface sediments from shallow to deep waters in the Campos Basin, one of the most important oil-producing provinces in Brazil. The observed levels of aliphatic (≤ 124 µg g-1) and polycyclic aromatic hydrocarbons (PAHs ≤ 599 ng g-1) are lower than those considered relevant for environmental risk to the benthic habitats. Higher median concentrations of aliphatic hydrocarbons (8.49 µg g-1) and PAHs (84.8 ng g-1) in the middle slope sediments (700-1000-m water depths) showed the influence of hydrodynamics upon hydrocarbon accumulation in the sediments. Diagnostic ratios and conventional statistical analysis applied to hydrocarbon data produced insufficient information on the contribution of different sources. These traditional approaches do not consider the potential changes affecting source assignment and therefore cannot deal with the uncertainties. The fuzzy logic applied as an alternative method for data treatment successfully incorporated the uncertainties in the differentiation between petrogenic and pyrolytic sources, including those due to degradation. Moreover, by using fuzzy logic, it was possible to identify that water circulation patterns, mass transport, deposition, and degradation processes are more relevant factors in determining hydrocarbon composition than source proximity.

Hydrocarbons and trace metals in mussels in the Macaé coast: Preliminary assessment for a coastal zone under influence of offshore oil field exploration in southeastern Brazil.

Concentrations of PAHs and metals were obtained from mussels collected in beaches, coastal island and estuary of the Macaé coast, the main operational basin for offshore oil exploration in Brazil. This survey provides reference levels for scenarios of increasing exploration, as well as for other areas of the coast undergoing urbanization to support exploration. As expected, urban areas such as the Macaé river estuary presented high concentrations of PAHs, although unsuspected sites such the island also presented signs of contamination. PAH in mussels originated from pyrolytic and petrogenic sources. Metals were typical of non-contaminated coastal environments, although Cr concentrations were above Brazilian Reference Levels.

Urban rivers as conveyors of hydrocarbons to sediments of estuarine areas: source characterization, flow rates and mass accumulation.

Aliphatic (n-C12-n-C40, unresolved complex mixture, resolved peaks) and aromatic hydrocarbons (46 PAH) were investigated in suspended particulate matter (SPM) sampled over eleven months in six of the major rivers and two channels of the Guanabara Bay Basin. PAH flow rates of the most contaminated rivers, the contribution to the PAH sediment load of the receiving bay, and the main sources of hydrocarbons were determined. PAH (38) ranged from 28 ng L(-1) to 11,514 ng L(-1). Hydrocarbon typology and statistical evaluation demonstrated contribution of distinct sources in different regions and allowed quantification of these contributions. Total flow rate for the five major rivers amounts to 3 t year(-1) and responds for 30% of the total PAH annual input into the northern area of the Guanabara Bay. For the first time PAH mass deposited in the bay sediments has been estimated and shall serve as base for decision making and source abatement.

Marine sponges as bioindicators of oil and combustion derived PAH in coastal waters.

The present study evaluates the potential of Hymeniacidon heliophila as bioindicator of PAH contamination. For this, concentration of 33 PAH was determined in organisms from sites with different contamination level including the heavily polluted Guanabara Bay, Rio de Janeiro, and less impacted coastal areas. PAH concentration and typology were determined in sponges collected from different depths and in two different seasons. The brown mussel broadly studied as bioindicator was also sampled from the same sites for comparison. Both species provided similar information on total PAH concentration which is related to site contamination level. Sponges, however, revealed slight tendency to accumulation of combustion-derived PAH in relation to petrogenic compounds. Differences in PAH typology between species may derive from the interspecific variation in particle size ingestion. Different hydrocarbon typologies were observed in sponges from dry and wet season and PAH concentration varied with depth. H. heliophila may be used as an alternative approach to investigate the presence and sources of PAH in estuarine areas.

Revisiting hydrocarbons source appraisal in sediments exposed to multiple inputs.

The aim of this work was to test the efficiency of statistical methods as compared to the traditional diagnostic ratios to improve hydrocarbon source identification in sediments subjected to multiple inputs. Hydrocarbon determination in Guanabara Bay sediments pointed out high degradation and ubiquitous petrogenic pollution through the presence of high unresolved complex mixture. Polycyclic aromatic hydrocarbon (PAHs) ratios suggested pervasive contamination derived from combustion in all sediments and failed discriminating samples despite the specificity of sources in different sampling sites. Principal component analysis (PCA) effectively distinguished the petrogenic imprint superimposed to the ubiquitous combustion contamination, since this technique reduces the influence of PAHs distribution which is common to all samples. PCA associated to multivariate linear regression (MLR) allowed a quantitative assessment of sources confirming predominance of the pervasive contaminant component superimposed to a generalized petrogenic imprint. The pervasive component derives from combustion contributions as well as from differential PAHs degradation.

Formation and identification of PAHs metabolites in marine organisms.

In this study, the development of the technique APCI(+) LC/MS/MS allowed the detection of phenanthrene, pyrene and metabolites of alkyl homologs in fish bile (in situ) and in urine of crabs. Laboratory experiments were carried out exposing crabs from an unpolluted mangrove (Barra de Guaratiba) to phenanthrene, and to the alkylated homologs 1-methyl phenanthrene and 2,6,9-trimethyl phenanthrene. Urine samples were collected at 0, 24, 48, 72, and 96 h. Fishes were captured from strategic sites from Guanabara Bay. Hydroxylated metabolites of phenanthrene, epoxides, orthoquinone and glucoside conjugates were identified in both samples. The method APCI(+) LC/MS/MS showed to be effective in a preliminary assessment of phenanthrene metabolite formation, although the low concentrations of 1-methyl phenanthene and 2,6,9-trimethyl phenanthrene did not allow a systematic evaluation of data. The method, however, proved to be excellent tool for studies of PAHs metabolites due to the high selectivity, sensitivity and separation attained.

Hydrocarbons in sediments of a chronically contaminated bay: the challenge of source assignment.

Aliphatic hydrocarbons and 39 PAH (parental and alkylated homologs) determined in ca. 100 sediment samples from the Guanabara Bay, Rio de Janeiro, were evaluated for source discrimination using new approaches. Concentrations of total PAH were in the range of 96-135,000 µg kg(-1) similar to other coastal urbanized embayment. Traditional diagnostic ratios were not as efficient PAH source indicators, e.g. biomass combustion was assigned as the major source of the pyrolytic PAH although the hydrographic basin is highly industrialized and urbanized. It is proved petrogenic imprint cannot be detected if only the 16 USEPA PAH are determined. The high production in the eutrophic system is not apparent in the aliphatic fraction dominated by land derived n-alkanes due to the effectiveness of microbial degradation. The present work demonstrates the complexity of hydrocarbon forensics when applied to chronically contaminated environments.

Hydrocarbon composition and distribution in a coastal region under influence of oil production in northeast Brazil.

Waters and sediments from the Potiguar Basin (NE Brazilian coast) were investigated for the presence and nature of polycyclic aromatic hydrocarbons (PAH) and aliphatic hydrocarbons. The region receives treated produced waters through a submarine outfall system serving the industrial district. The total dispersed/dissolved concentrations in the water column ranged from 10-50 ng L(-1) for ∑16PAH and 5-10 µg L(-1) for total aliphatic hydrocarbons. In the sediments, hydrocarbon concentrations were low (0.5-10 ng g(-1)for ∑16PAH and 0.01-5.0 µg g(-1) for total aliphatic hydrocarbons) and were consistent with the low organic carbon content of the local sandy sediments. These data indicate little and/or absence of anthropogenic influence on hydrocarbon distribution in water and sediment. Therefore, the measured values may be taken as background values for the region and can be used as future reference following new developments of the petroleum industry in the Potiguar Basin.

Biomarkers of PAHs exposure in crabs Ucides cordatus: laboratory assay and field study.

Pyrene metabolites in urine and micronucleus in haemocytes of crabs (Ucides cordatus) were tested as biomarkers of exposure to oil derived PAHs in mangrove sediments. The goal was to verify how well pyrene metabolites in urine represent levels of oil contamination in mangroves and whether the micronuclei assay indicates exposure. For this, bioassays were performed using crabs from clean and contaminated areas, and field studies were conducted in four mangroves. Results of the bioassay show that U. cordatus assimilates, metabolises, and excretes pyrene in urine as pyrene-1-glucoside, pyrene-sulphate and pyrene-conjugate. OH-pyrene-sulphate was the major metabolite produced/excreted over 120 h of observation by crabs from the clean mangrove. The production/excretion of pyrene-1-glucoside in this case increased linearly with time at a rate of 2.3 x 10(-10)mol L(-1)day(-1). The number of micronuclei in haemocytes also increased with the time after pyrene inoculation, indicating that exposure to pyrene triggers genotoxic and mutagenic response. In crabs from a heavily oil-contaminated mangrove pyrene-1-glucoside was the major metabolite, an indication that production/excretion of a certain metabolite varies depending on adaptation of the animal to the environment. A highly significant correlation was found between the concentration of pyrene metabolites in urine of field crabs expressed as OH-pyrene equivalents and the sum of 38 PAHs determined in hepatopancreas/sediments (r=0.825, n=23, p<0.05). The response of these crabs to the micronuclei assay was not significantly related to concentration of individual or total PAHs. Nevertheless, metabolite results prove U. cordatus as excellent bioindicator for evaluating environmental quality in mangrove areas as related to PAHs and oil contamination.

Distribution of copper in the vicinity of a deactivated mining site at Carajás in the Amazon region of Brazil.

In this work the re-fixation of mobilized copper (Cu) that was released from a deactivated pilot Cu ore dressing plant in the tropical rain forest at Southeastern Amazon (Carajás) was studied. Samples of top soils, decay leaf litter deposited on soils, roots and leaves of standing biomass were taken for the determination of Cu concentration in order to evaluate the distribution of it between different environmental compartments. In the sampling points near to the now extinct plant, total Cu concentrations in the soil reached an average value of 2140 microg g(-1) above the natural level of about 40 microg g(-1), being that bioavailable Cu estimated by DTPA method varied from 1.9 to 20.7% of this total. From the data was possible to calculate that the soil compartment is able to hold around 10 kg Cu/m(2) of ground. Roots of the standing biomass in that area hold around 17 g Cu/m(2), while the Cu content in leaves showed to be largely independent of the Cu level in the soil. Copper in the leaves was estimated as around 1g/m(2) of ground area. In turn, the decay leaf litter deposited on soil can hold about 1.6 g Cu/m(2). The terrestrial system surrounding the abandoned pilot plant demonstrated great buffer capacity to retain mobile Cu released by anthropogenic activities in the area.

Constraints to the implementation of effective environmental management in coastal areas of developing countries.

This paper addresses the limitations the scarcity of reliable scientific information poses to the implementation of effective and sustainable coastal management programmes in developing countries. Alternatives to the current monitoring approaches are suggested as to improve information level on the state of the environment and to decrease data gap on past conditions. The paper aims at encouraging the redesign of monitoring practices in developing countries as to be ground on the best actual scientific knowledge.

Constraints to the implementation of effective environmental management in coastal areas of developing countries

O presente texto trata das limitações, impostas pela escassez de informação científica confiável, à implementação de programas eficazes e sustentáveis de gestão costeira em paises em desenvolvimento. São sugeridas alternativas às abordagens correntes de monitoramento, as quais visam aprimorar o nível de conhecimento sobre o estado do meio ambiente e decrescer a carência de dados sobre suas condições pretéritas. As discussões apresentadas pretendem encorajar o redesenho das práticas de monitoramento em países em desenvolvimento de forma que passem a se fundamentar no melhor conhecimento científico atual.