Benthic foraminifera as proxies for assessing the effects of a pier marina construction: A case study in the naturally stressed environment of the Saco da Ribeira (Flamengo Bay, SE Brazil).

Brazilian coastal areas have been exposed to various anthropic influences including physical alteration such as marina construction. To assess the impact of the pier marina construction in the Saco da Ribeira cove (Flamengo Bay, SE Brazil), sedimentological (grain size), geochemical (organic and trace elements) parameters and benthic foraminifera were analyzed on a 50-cm-long dated sediment core covering the last century. The multiproxy approach applied to a numerical hydrodynamic model shows that the circulation in the study area underwent an overall reduction (ca. 30 %) after the pier marina construction in the 1970s, promoting an increase of mud accumulation and higher concentrations of total organic carbon and trace elements (i.e., Enrichment Factor Cu from 0.80 to 1.4) as well as a shift in the benthic foraminiferal assemblages (i.e., foraminiferal density from 63 to 23.20 specimens per 10 cm3 and dominance from 0.13 to 0.73). On the basis of these integrated data, better environmental conditions occurred before the 1970s, then an overall increase in environmental stress took place after the pier's marina construction. Our results provide a baseline for future biomonitoring projects in a stressed region and exemplify the strong capability and reliability of benthic foraminifera as bioindicators of paleoenvironmental changes in coastal environments and for understanding how human pressure might induce such changes.

Unusual natural polycyclic aromatic hydrocarbons in sediment cores of an Amazon estuary.

Polycyclic aromatic hydrocarbons (PAHs) most likely derived from natural sources were observed in two sediment cores covering the last 100 years in an Amazon estuarine region. A considerable change in the PAHs main source was observed in the 1960s. Before the 1960s, the sources of PAHs seem to be related to biogenic and/or early-diagenetic processes. Concentrations of perylene were higher before the 1960s and suggest that its primary source to the sediments in the Amazon region is linked to a short-term diagenetic transformation of their biogenic precursors. The natural formation of alkylated PAHs in sediments was linked to the methylation of the parental aromatic hydrocarbons due to sediment maturation processes and the dehydrogenation of sterols in the sediments. The relatively rapid reaction occurring in recent sediments of the Amazon region suggests the importance of the microbial community in the transformation of biogenic precursors to alkylated-PAHs in the sediments.

Depositional input of hydrocarbons recorded in sedimentary cores from Deception and Penguin Islands (South Shetland Archipelago, Antarctica).

Polycyclic aromatic hydrocarbons (PAHs) and aliphatic hydrocarbons (AHs), including petroleum biomarkers, were studied in four sediment cores collected around Deception and Penguin Islands, Antarctica. Total PAHs in Deception Island (DCP) samples ranged from 2.0 to 26.8 ng g-1, and in Penguin Island (PGI) varied between 13.2 and 60.3 ng g-1. Multiple sources of PAHs were verified in DCP, with petrogenic-derived compounds being predominant over the last 10 years. In PGI, PAHs related to natural contributions from the erosion of coal deposits were reported. Total AHs in DCP ranged from 4.5 to 19 µg g-1 and in PGI varied between 5.3 and 21.9 µg g-1. In DCP, the n-alkanes distribution pattern showed the presence of petroleum residues in the top sections and both terpanes and hopanes were detected, related to the use of fossil fuels for power generation and in different types of vessels. In PGI, the main source of n-alkanes was marine inputs and only terpanes were detected. The slight increase in hydrocarbon levels observed from 1980 onward in DCP was assumed to be due to the development of tourism in the region and to the scientific station activities. In PGI, anthropogenic-related hydrocarbons were detected in the recent sections and were linked to the development of tourism near the island, scientific activities and the increase in vessel traffic. In general, the concentrations of hydrocarbons found around both islands were comparable to those found in uncontaminated Antarctic regions.

Depositional history of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) in an Amazon estuary during the last century.

The sources and depositional history of OCPs (organochlorine pesticides), PCBs (polychlorinated biphenyls) and PAHs (polycyclic aromatic hydrocarbons) over the last 100years were determined in two sediment cores collected in the Amazon region. It was possible to distinguish two depositional periods along the cores. The first period occurred before extensive anthropogenic effects were registered in the sediments. During this time interval, the concentrations of all OCPs and PCBs were below the detection limits (DL), and the PAH concentrations were low and essentially constant (58.19-124.28ngg-1). The second period starts in the mid-1960s and reflects the increased human influence in the area. The concentrations of OCPs, PCBs, and PAHs increased towards the top of the cores, varying between

Coupling spectroscopic and chromatographic techniques for evaluation of the depositional history of hydrocarbons in a subtropical estuary.

Spectroscopic and chromatographic techniques can be used together to evaluate hydrocarbon inputs to coastal environments such as the Paranaguá estuarine system (PES), located in the SW Atlantic, Brazil. Historical inputs of aliphatic hydrocarbons (AHs) and polycyclic aromatic hydrocarbons (PAHs) were analyzed using two sediment cores from the PES. The AHs were related to the presence of biogenic organic matter and degraded oil residues. The PAHs were associated with mixed sources. The highest hydrocarbon concentrations were related to oil spills, while relatively low levels could be attributed to the decrease in oil usage during the global oil crisis. The results of electron paramagnetic resonance were in agreement with the absolute AHs and PAHs concentrations measured by chromatographic techniques, while near-infrared spectroscopy results were consistent with unresolved complex mixture (UCM)/total n-alkanes ratios. These findings suggest that the use of a combination of techniques can increase the accuracy of assessment of contamination in sediments.

Assessment of historical fecal contamination in Curitiba, Brazil, in the last 400 years using fecal sterols.

A 400-year sedimentary record of the Barigui River was investigated using fecal biomarkers and nutrient distribution. The temporal variability in cholesterol, cholestanol, coprostanol, epicoprostanol, stigmastanol, stigmasterol, stigmastenol, sitosterol, and campesterol between 1600 and 2011 was assessed. Anthropogenic influences, such as deforestation and fecal contamination from humans and livestock, were observed from 1840. The sterol ratios exhibit evidence of hens, horses, cows, and an unknown herbivore, which may be a capybara (Hydrochoerus hydrochaeris), from 1820 and has been observed more markedly from 1970 onward. Human fecal contamination was detected from 1840 and was observed more markedly from 1930 due to population growth. Thus, the sanitation conditions and demographic growth of Curitiba seemed to be the main factors of human sewage pollution, as the coprostanol concentration over time was strongly correlated with the population growth (r=0.71, p<0.001) although diagenetic processes have also been observed.(1.)

Sedimentary record of PAHs in the Barigui River and its relation to the socioeconomic development of Curitiba, Brazil.

Concentrations of polycyclic aromatic hydrocarbons (PAHs) were determined in a sediment core collected from the Barigui River, in Curitiba, South Brazil. The USEPA's 16 priority PAH concentrations ranged from 39ng g(-1) to 2350ng g(-1) of dry sediment over a period that corresponds temporally to between ca. 1855 and 2011. The concentrations and patterns of PAH distribution changed over this time period and may be associated with several episodes in the Curitiba's history. Two major PAHs concentration peaks occurred in approximately 1910 and 1970, which might reflect population increases due to immigration programs in the 1890s and the sudden economic development that occurred in Brazil from 1960 to 1980, "The Economic Miracle Period", respectively. Isomeric ratios revealed that the PAHs had predominantly pyrolytic sources. The population, number of highways and electric energy consumption of Curitiba, as indices of socioeconomic development, were positively correlated with PAH deposition in the sediment core from 1855 to 1970, indicating the influence of socioeconomic development on the environmental load of sedimentary PAHs.