Importance of freshwater flow in terrestrial–aquatic energetic connectivity in intermittently connected estuaries of tropical Australia

δ¹³C was used to identify seasonal variations in the importance of autochthonous and allochthonous sources of productivity for fish communities in intermittently connected estuarine areas of Australia’s dry tropics. A total of 224 fish from 38 species were collected from six intermittently connected estuarine pools, three in central Queensland (two dominated by C₃ forest and one by C₄ pasture) and three in north Queensland (one dominated by C₃ and two by C₄ vegetation). Samples were collected before and after the wet season. Fish collected in the two forested areas in central Queensland had the lowest δ¹³C, suggesting a greater incorporation of C₃ terrestrial material. A seasonal variation in δ¹³C was also detected for these areas, with mean δ¹³C varying from −20 to −23‰ from the pre- to the post-wet season, indicating a greater incorporation of terrestrial carbon after the wet season. Negative seasonal shifts in fish δ¹³C were also present at the pasture site, suggesting a greater dependence on carbon of riparian vegetation (C₃ Juncus sp.) in the post-wet season. In north Queensland, terrestrial carbon seemed to be incorporated by fish in the two C₄ areas, as δ¹³C of most species shifted towards slightly heavier values in the post-wet season. A two-source, one-isotope mixing model also indicated a greater incorporation of carbon of terrestrial origin in the post-wet season. However, no seasonal differences in δ¹³C were detected for fish from the forested area of north Queensland. Overall, hydrologic connectivity seemed to be a key factor in regulating the ultimate sources of carbon in these areas. It is therefore important to preserve the surrounding habitats and to maintain the hydrologic regimes as close to natural conditions as possible, for the conservation of the ecological functioning of these areas.     

Comparing spatial and temporal changes in metal trends (Cr,Ni, Pb and Zn) on the Portuguese shelf since the 1970s

Comparison between an archive dataset, collected during the 1970s (1974–1977), and samples taken during the PALEO1 cruise (2002) enabled evaluation of large-scale and long-term spatiotemporal changes in Al, Cr, Ni, Pb and Zn contents in bulk surface sediments in four areas of the Portuguese shelf. The so-called gradient method (GM) with normalisation to Al, a proxy for terrigenous clay content, was applied. The studied areas are distributed from north to south along the western margin, with the northernmost located off shore the Ave and Douro rivers, a central one located off shore the Lis River and a southern one located off shore the Mira River. One-way ANOVA and Kruskal-Wallis tests were used to identify differences among study areas and periods of sample collection. A comparison of metal contents in 2002 samples with the Portuguese classification scheme regulation for deposition of dredged materials in coastal areas indicates good environmental quality in terms of Cr, Ni, Pb and Zn levels. Nevertheless, the GM results suggest an increase in metal loadings relative to Al from the 1970s to the 2002 samples (except for Pb). The Algarve area on the southern shelf is characterised by having high number of sites with metal level on class 2. These high values have traditionally been explained by a substantial supply of natural metals from the Guadiana, Tinto and Odiel rivers that drain areas Iberian Pyrite Belt formations. This supply has probably been magnified by present and past mining activities. For quality evaluation of marine sediments, especially when using total metal contents, this study shows the importance of considering all possible sources of metal loading. The natural grain size and composition variability have also a crucial influence on the metal content, and the combined evaluation allows a more holistic perspective.     

Peri-urban agro-ecosystems in the Mediterranean: diversity,dynamics, and drivers

Regional Environmental Change - To address sustainability challenges of agro-ecosystems located in Mediterranean urban regions, this paper focuses on the multidisciplinary subject of urban...     

Emission of polycyclic aromatic hydrocarbons from gasohol and ethanol vehicles

The exhaust emission of the polycyclic aromatic hydrocarbons (PAHs) considered toxic to human health were investigated on two spark ignition light duty vehicles, one being gasohol (Gasohol, in Brazil, is the generic denomination for mixtures of pure gasoline plus 20–25% of anhydrous ethyl alcohol fuel (AEAF).)-fuelled and the other a flexible-fuel vehicle fuelled with hydrated ethanol. The influence of fuel type and quality, aged lubricant oil type and use of fuel additives on the formation of these compounds was tested using standardized tests identical to US FTP-75 cycle. PAH sampling and chemical analysis followed the basic recommendations of method TO-13 (United States. Environmental Protection Agency, 1999. Compendium Method TO-13A – Determination of polycyclic Aromatic hydrocarbons (PAH) in Ambient Air Using Gas Chromatography/Mass Spectrometry (CG/MS). Center for environmental research information, Cincinnati, p. 78), with the necessary modification for this particular application.Results showed that the total PAH emission factor varied from 41.9 μg km^?1 to 612 μg km^?1 in the gasohol vehicle, and from 11.7 μg km^?1 to 27.4 μg km^?1 in the ethanol-fuelled vehicle, a significant difference in favor of the ethanol vehicle. Generally, emission of light molecular weight PAHs was predominant, while high molecular weights PAHs were not detected. In terms of benzo(a)pyrene toxicity equivalence, emission factors varied from 0.00984 μg TEQ km^?1 to 4.61 μg TEQ km^?1 for the gasohol vehicle and from 0.0117 μg TEQ km^?1 to 0.0218 μg TEQ km^?1 in the ethanol vehicle.For the gasohol vehicle, results showed that the use of fuel additive causes a significant increase in the emission of naphthalene and phenanthrene at a confidence level of 90% or higher; the use of rubber solvent on gasohol showed a reduction in the emission of naphthalene and phenanthrene at the same confidence level; the use of synthetic oil instead of mineral oil also contributed significantly to a decrease in the emission of naphthalene and fluorene. In relation to the ethanol vehicle, the same factors were tested and showed no statistically significant influence on PAH emission.     

Regional geochemical baselines for Portuguese shelf sediments

Metal concentrations (Al, Cr, Cu, Ni, Pb and Zn) from the DGM-INETI archive data set have been examined for sediments collected during the 1970s from 267 sites on the Portuguese shelf. Due to the differences in the oceanographic and sedimentological settings between western and Algarve coasts, the archive data set is split in two segments. For both shelf segments, regional geochemical baselines (RGB) are defined using aluminium as a reference element. Seabed samples recovered in 2002 from four distinct areas of the Portuguese shelf are superimposed on these models to identify and compare possible metal enrichments relative to the natural distribution. Metal enrichments associated with anthropogenic influences are identified in three samples collected nearby the Tejo River and are characterised by the highest enrichment factors (EF; EF(Pb)<3, EF(Zn)<4). EF values close to 1 suggest a largely natural origin for metal distributions in sediments from the other areas included in the study.     

Comparison of emission of dioxins and furans from gasohol- and ethanol-powered vehicles

The exhaust emissions of 17 polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) were investigated in two spark-ignition light-duty vehicles, one gasohol-fueled and a flexible-fuel one fueled with hydrated ethanol. Gasohol is a mixture of gasoline and 22% ethanol. The influence of fuel type and quality, lubricant oil type, and use of fuel additives on the formation of these compounds was tested using standardized U.S. Federal Test Procedure (FTP)-75 cycle tests. The sampling of the PCDD/Fs followed the recommendations of a modified U.S. Environmental Protection Agency (EPA) Method 23 (www.epa.gov/ttn/ emc/promgate/m-23.pdf) and the analysis basically followed the U.S. EPA Method 8290 (http://www.epa.gov/osw/ hazard/testmethods/sw846/pdfs/8290a.pdf). Results showed that emission factors of PCDD/Fs for the.gasohol vehicle varied from undetected to 0.068 pg international toxic equivalency (I-TEQ) km(-1) (average of 0.0294 pg I-TEQ km(-1)), whereas in the ethanol vehicle they varied from 0.004 to 0.157 pg (I-TEQ) km(-1) (average of 0.031 pg I-TEQ km(-1)). In the gasohol-powered vehicle, the use of fuel additive diminished the emission of Octachlorodibenzo-p-dioxin (OCDD) significantly, whereas in the ethanol vehicle no significant associations were observed between the investigated variables and the emissions.     

Comparison of Emission of Dioxins and Furans from Gasohol- and Ethanol-Powered Vehicles

ABSTRACT

The exhaust emissions of 17 polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) were investigated in two spark-ignition light-duty vehicles, one gasohol-fueled and a flexible-fuel one fueled with hydrated ethanol. Gasohol is a mixture of gasoline and 22% ethanol. The influence of fuel type and quality, lubricant oil type, and use of fuel additives on the formation of these compounds was tested using standardized U.S. Federal Test Procedure (FTP)-75 cycle tests. The sampling of the PCDD/Fs followed the recommendations of a modified U.S. Environmental Protection Agency (EPA) Method 23 (http://www.epa.gov/ttn/emc/promgate/m-23.pdf) and the analysis basically followed the U.S. EPA Method 8290 (http://www.epa.gov/osw/hazard/testmethods/sw846/pdfs/8290a.pdf). Results showed that emission factors of PCDD/Fs for the gasohol vehicle varied from undetected to 0.068 pg international toxic equivalency (I-TEQ) km^?1 (average of 0.0294 pg I-TEQ km^?1), whereas in the ethanol vehicle they varied from 0.004 to 0.157 pg (I-TEQ) km^?1 (average of 0.031 pg I-TEQ km^?1). In the gasohol-powered vehicle, the use of fuel additive diminished the emission of Octachlorodibenzo-p-dioxin (OCDD) significantly, whereas in the ethanol vehicle no significant associations were observed between the investigated variables and the emissions.

IMPLICATIONS The objective of this work was to analyze differences in emissions from a traditional fossil fuel (gasoline) and an alternative renewable fuel (ethanol from sugarcane), and the influence of fuel additives and lubricant oils on the formation of chlorinated dioxins and furans in spark-ignition light-duty gasohol and ethanol vehicles. Renewable fuels are very important in terms of climate change but the risk to the population's health must not increase. Thus the results of this work could help in the development of environmental impact studies as well as orienting policy-makers in formulating strategies for air pollution control.     

First Step for an Ecological Risk Assessment to Evaluate the Impact of Diffuse Pollution in Lake Vela (Portugal)

Lake Vela, located in the Portuguese littoral-centre, is a temperate shallow lake exhibiting a high trophic status. This aquatic ecosystem has been potentially exposed to contamination generated by agricultural and livestock activities held in their drainage basin, which seriously compromise their health. This work summarizes some background information and presents the problem formulation step of the ERA. Therefore, it evaluates the characteristics of the stressor(s), describes the ecological system and receptors and suggests a conceptual model, which predicts the potential exposure pathways, relating suspected sources to the defined endpoints. This introductory step also described an analysis plan on the entire study, which includes a delineation of the assessment design, data needs, measures, and methods for conducting the analysis phase of the risk assessment process.