Emissions tradeoffs among alternative marine fuels: total fuel cycle analysis of residual oil, marine gas oil, and marine diesel oil

Worldwide concerns about sulfur oxide (SOx) emissions from ships are motivating the replacement of marine residual oil (RO) with cleaner, lower-sulfur fuels, such as marine gas oil (MGO) and marine diesel oil (MDO). Vessel operators can use MGO and MDO directly or blended with RO to achieve environmental and economic objectives. Although expected to be much cleaner in terms of criteria pollutants, these fuels require additional energy in the upstream stages of the fuel cycle (i.e., fuel processing and refining), and thus raise questions about the net impacts on greenhouse gas emissions (primarily carbon dioxide [CO2]) because of production and use. This paper applies the Total Energy and Environmental Analysis for Marine Systems (TEAMS) model to conduct a total fuel cycle analysis of RO, MGO, MDO, and associated blends for a typical container ship. MGO and MDO blends achieve significant (70-85%) SOx emissions reductions compared with RO across a range of fuel quality and refining efficiency assumptions. We estimate CO2 increases of less than 1% using best estimates of fuel quality and refinery efficiency parameters and demonstrate how these results vary based on parameter assumptions. Our analysis suggests that product refining efficiency influences the CO2 tradeoff more than differences in the physical and energy parameters of the alternative fuels, suggesting that modest increases in CO2 could be offset by efficiency improvements at some refineries. Our results help resolve conflicting estimates of greenhouse gas tradeoffs associated with fuel switching and other emissions control policies.     

Effect of climate change on flux of N and C: air-land-freshwater-marine links: synthesis

Projected climate change might increase the deposition of nitrogen by about 10% to seminatural ecosystems in southern Norway. At Storgama, increased precipitation in the growing season increased the fluxes of total organic carbon (TOC) and total organic nitrogen (TON) in proportion to the water flux. In winter, soil temperatures near 0 degrees C, common under a snowpack, induced higher runoff of inorganic nitrogen (N) and lower runoff of TOC. By contrast, soil temperatures below freezing, caused by little snow accumulation (expected in a warmer world), reduced runoff of inorganic N, TON, and TOC. Long-term monitoring data showed that reduced snowpack can cause either decreased or increased N leaching, depending on interactions with N deposition, soil temperature regime, and winter discharge. Seasonal variation in TOC was mainly climatically controlled, whereas deposition of sulfate and nitrate (NO3) explained the long-term TOC increase. Upscaling to the river basin scale showed that the annual flux of NO3 will remain unchanged in response to climate change projections.     

Photocatalytic and combined anaerobic-photocatalytic treatment of textile dyes

A photocatalytic process based on immobilized titanium dioxide was used to treat crude solutions of azo, anthraquinone and phthalocyanine textile dyes. In addition, the process was applied to the treat autoxidized chemically reduced azo dyes, i.e. representatives of recalcitrant dye residues after biological sequential anaerobic-aerobic treatment. Photocatalysis was able to remove more than 90% color from crude as well as autoxidized chemically reduced dye solutions. UV-absorbance and COD were also removed but to a lower extent (50% in average). The end products of photocatalytic treatment were not toxic toward methanogenic bacteria. The results demonstrate that photocatalysis can be used as a pre- or post-treatment method to biological anaerobic treatment of dye-containing textile wastewater.     

Long-term survey of heavy-metal pollution, biofilm contamination and diatom community structure in the Riou Mort watershed, South-West France

In a metal-polluted stream in the Riou Mort watershed in SW France, periphytic biofilm was analyzed for diatom cell densities and taxonomic composition, dry weight and metal bio-accumulation (cadmium and zinc). Periphytic diatom communities were affected by the metal but displayed induced tolerance, seen through structural impact (dominance of small, adnate species) as well as morphological abnormalities particularly in the genera Ulnaria and Fragilaria. Species assemblages were characterized by taxa known to occur in metal-polluted environments, and shifts in the community structure expressed seasonal patterns: high numbers of Eolimna minima, Nitzschia palea and Pinnularia parvulissima were recorded in Summer and Autumn, whereas the species Surirella brebissonii, Achnanthidium minutissimum, Navicula lanceolata and Surirella angusta were dominant in Winter and Spring. Commonly used indices such as the Shannon diversity index and Specific Pollution Sensitivity Index reflected the level of pollution and suggest seasonal periodicity, the lowest diversities being observed in Summer.     

PAHs in background soils from Western Europe: influence of atmospheric deposition and soil organic matter

The levels and distribution of polynuclear aromatic hydrocarbons (PAHs) were determined in soil samples from background locations in the UK and Norway, to investigate their spatial distribution and the controlling environmental factors. Concentrations ranged between 42 and 11200 microg kg(-1) (geometric mean 640 microg kg(-1)) and 8.6 and 1050 microg kg(-1) (150 microg kg(-1)) dry weight in the UK and Norwegian soil, respectively. Proximity to sources and locations susceptible to high atmospheric depositional inputs resulted in higher concentrations. Statistically significant relationships were observed between PAH and total organic carbon (TOC) in the Norwegian samples. High molecular weight PAHs correlated with black carbon (BC) in UK-woodland soil. These observations support the hypothesis that TOC plays an important role in the retention of PAHs in soil and that PAHs are often combined with BC during combustion emissions. PAHs with 4 and more rings comprised approximately 90% of total PAHs in the UK soil, but only 50% in the Norwegian soil. The mixture of PAHs implied that fractionation occurred during long-range atmospheric transport and deposition. The lighter PAHs with lower K(ow) values more readily reached the most remote sites. The heavier PAHs with higher K(ow) values remained in closer proximity to sources.     

Heavy metals' content of automotive shredder residues (ASR): evaluation of environmental risk

Every year between 8 and 9 millions of vehicles in the European Union arrive to their end of life. Car wastes can have a very high metal content, falling into hazardous waste class. A preliminary evaluation of these wastes could be made by metals' leaching test runs which is the main objective of the present study. Evaluation of the total metal content was carried out by X-ray fluorescence and the mobility of these metals using two simple standardized extractions such as the TCLP (Toxicity Characterisation Leaching Procedure) of the US EPA and the German leaching test DIN 38414-S4. Additionally, an extraction test with acetone was performed in order to recognise metals bounded to organic matter. The results show that the total metal content of the ASR can overpass the established values for inert residues. Lead and zinc contents are fairly well correlated with grain-size, whilst other metals' contents do not exhibit clear grain-size dependence.     

A strategy for aromatic hydrocarbon bioremediation under anaerobic conditions and the impacts of ethanol: a microcosm study

Increased use of ethanol-blended gasoline (gasohol) and its potential release into the subsurface have spurred interest in studying the biodegradation of and interactions between ethanol and gasoline components such as benzene, toluene, ethylbenzene and xylene isomers (BTEX) in groundwater plumes. The preferred substrate status and the high biological oxygen demand (BOD) posed by ethanol and its biodegradation products suggests that anaerobic electron acceptors (EAs) will be required to support in situ bioremediation of BTEX. To develop a strategy for aromatic hydrocarbon bioremediation and to understand the impacts of ethanol on BTEX biodegradation under strictly anaerobic conditions, a microcosm experiment was conducted using pristine aquifer sand and groundwater obtained from Canadian Forces Base Borden, Canada. The initial electron accepter pool included nitrate, sulfate and/or ferric iron. The microcosms typically contained 400 g of sediment, 600 approximately 800 ml of groundwater, and with differing EAs added, and were run under anaerobic conditions. Ethanol was added to some at concentrations of 500 and 5000 mg/L. Trends for biodegradation of aromatic hydrocarbons for the Borden aquifer material were first developed in the absence of ethanol, The results showed that indigenous microorganisms could degrade all aromatic hydrocarbons (BTEX and trimethylbenzene isomers-TMB) under nitrate- and ferric iron-combined conditions, but not under sulfate-reducing conditions. Toluene, ethylbenzene and m/p-xylene were biodegraded under denitrifying conditions. However, the persistence of benzene indicated that enhancing denitrification alone was insufficient. Both benzene and o-xylene biodegraded significantly under iron-reducing conditions, but only after denitrification had removed other aromatics. For the trimethylbenzene isomers, 1,3,5-TMB biodegradation was found under denitrifying and then iron-reducing conditions. Biodegradation of 1,2,3-TMB or 1,2,4-TMB was slower under iron-reducing conditions. This study suggests that addition of excess ferric iron combined with limited nitrate has promise for in situ bioremediation of BTEX and TMB in the Borden aquifer and possibly for other sites contaminated by hydrocarbons. This study is the first to report 1,2,3-TMB biodegradation under strictly anaerobic condition. With the addition of 500 mg/L ethanol but without EA addition, ethanol and its main intermediate, acetate, were quickly biodegraded within 41 d with methane as a major product. Ethanol initially present at 5000 mg/L without EA addition declined slowly with the persistence of unidentified volatile fatty acids, likely propionate and butyrate, but less methane. In contrast, all ethanol disappeared with repeated additions of either nitrate or ferric iron, but acetate and unidentified intermediates persisted under iron-enhanced conditions. With the addition of 500 mg/L ethanol and nitrate, only minor toluene biodegradation was observed under denitrifying conditions and only after ethanol and acetate were utilized. The higher ethanol concentration (5000 mg/L) essentially shut down BTEX biodegradation likely due to high EA demand provided by ethanol and its intermediates. The negative findings for anaerobic BTEX biodegradation in the presence of ethanol and/or its biodegradation products are in contrast to recent research reported by Da Silva et al. [Da Silva, M.L.B., Ruiz-Aguilar, G.M.L., Alvarez, P.J.J., 2005. Enhanced anaerobic biodegradation of BTEX-ethanol mixtures in aquifer columns amended with sulfate, chelated ferric iron or nitrate. Biodegradation. 16, 105-114]. Our results suggest that the apparent conservation of high residual labile carbon as biodegradation products such as acetate makes natural attenuation of aromatics less effective, and makes subsequent addition of EAs to promote in situ BTEX biodegradation problematic.     

Comparison of arsenic resistance in Mediterranean woody shrubs used in restoration activities

Myrtus communis, Arbutus unedo and Retama sphaerocarpa are Mediterranean shrubs widely used in revegetation of semiarid degraded soils. The aim of this work is to study the resistance of these plants to arsenic under controlled conditions, in order to evaluate their potential use in revegetation and/or phytoremediation of As-polluted soils. R. sphaerocarpa showed higher resistance to As than M. communis or A. unedo according to its higher EC50, P status and P/As molar ratio in both, roots and shoots, and the lower increases in lipid peroxidation and decrease of chlorophyll levels in response to arsenic, while the highest arsenate sensitivity was obtained for A. unedo. Arsenic was mainly retained in roots, and, although M. communis accumulated higher arsenic amounts than the other two species, R. sphaerocarpa showed the highest root to shoot transfer. Most of the studied parameters (chlorophylls, MDA and total thiols) showed significant correlation with arsenic concentration in roots and leaves of plants, so they can be useful indexes in the diagnosis of arsenic toxicity in these species. According to our results, both M. communis and R. sphaerocarpa could be used in the revegetation of moderately arsenic contaminated sites.     

Polychlorinated biphenyls (PCBs) and hydroxy-PCBs in adipose tissue of women in Southeast Spain

Polychlorinated biphenyls (PCBs) and hydroxylated PCBs (OH-PCBs) were investigated in human adipose tissue samples collected from 20 women undergoing surgery. Mean sum of PCB and sum of OH-PCB levels were 737ng/g of lipid and 8pg/g of lipid, respectively. Among PCBs, congeners 180, 153, 138 and 170 were the most frequent and abundant, and together constituted 72% of the total amount of PCBs in adipose tissue. The PCB congener pattern and the frequencies and concentrations of non-dioxin-like and non-hydroxylated congeners observed in adipose tissue were similar in distribution and order of magnitude to the profile previously published in Spain but lower than that found in other European countries. Among OH-PCB congeners studied, 4-OH-PCB 107/118 was found at the highest concentrations followed by 3'-OH-PCB 180 and 3-OH-PCB 138. To date, no information on levels of PCB metabolites in the Spanish population is available for comparison. These three predominant OH-PCBs contributed 97% of all OH-PCBs. Twelve dioxin-like PCBs contributed around 8% of the total PCB exposure, and all were present in all study subjects. Further research is required to determine trends in human exposure to PCBs and OH-PCBs and how existing banning measures affect exposure.     

Mobilisation of sediment-associated metals from historical Pb working sites on the River Sheaf, Sheffield, UK

Spatial and temporal patterns of metal mobilisation from former water-powered, Pb working sites in a suburban area of Sheffield (UK) were investigated. Twelve time-integrated mass flux samplers were strategically deployed over two contrasting campaign periods (summer and winter). Suspended sediment samples were characterised magnetically and subjected to metal analysis. Metal levels in the upper River Sheaf showed a marked spatial and temporal variability. Pb concentrations in particular were relatively high (maximum 2132 mg kg(-1)). Their distribution tended to reflect the historical contamination of the valley by 17th to 19th century industry, especially during summer high discharge conditions. The mean suspended sediment Pb concentration (803 mg kg(-1)) exceeds contamination guidelines. It is unclear whether ground remediation of one of the seven floodplain sites in the catchment has been successful. The river is still affected by the legacy of at least two other Pb working sites.