Little attention has been devoted to the effects on children's respiratory health of exposure to sulphur dioxide (SO2) in ambient air from local industrial emissions. Most studies on the effects of SO(2) have assessed its impact as part of the regional ambient air pollutant mix.
To examine the association between exposure to stack emissions of SO(2) from petroleum refineries located in Montreal's (Quebec) east-end industrial complex and the prevalence of active asthma and poor asthma control among children living nearby.
The present cross-sectional study used data from a respiratory health survey of Montreal children six months to 12 years of age conducted in 2006. Of 7964 eligible households that completed the survey, 842 children between six months and 12 years of age lived in an area impacted by refinery emissions. Ambient SO(2) exposure levels were estimated using dispersion modelling. Log-binomial regression models were used to estimate crude and adjusted prevalence ratios (PRs) and 95% CIs for the association between yearly school and residential SO(2) exposure estimates and asthma outcomes. Adjustments were made for child's age, sex, parental history of atopy and tobacco smoke exposure at home.
The adjusted PR for the association between active asthma and SO(2) levels was 1.14 (95% CI 0.94 to 1.39) per interquartile range increase in modelled annual SO(2). The effect on poor asthma control was greater (PR=1.39 per interquartile range increase in modelled SO(2) [95% CI 1.00 to 1.94]).
Results of the present study suggest a relationship between exposure to refinery stack emissions of SO(2) and the prevalence of active and poor asthma control in children who live and attend school in proximity to refineries.
Arctic shipping and oil exploration are expected to increase, as sea ice extent is reduced. This enhances the risk for accidental oil spills throughout the Arctic, which emphasises the need to quantify potential consequences to the marine ecosystem and to evaluate risk and choose appropriate remediation methods. This study investigated the sensitivity of Arctic marine plankton to the water accommodated fraction (WAF) of heavy fuel oil. Arctic marine phytoplankton and copepods (Calanus finmarchicus) were exposed to three WAF concentrations corresponding to total hydrocarbon contents of 0.07?mg?l-1, 0.28?mg?l-1 and 0.55?mg?l-1. Additionally, the potential phototoxic effects of exposing the WAF to sunlight, including the UV spectrum, were tested. The study determined sub-lethal effects of WAF exposure on rates of key ecosystem processes: primary production of phytoplankton and grazing (faecal pellet production) of copepods. Both phytoplankton and copepods responded negatively to WAF exposure. Biomass specific primary production was reduced by 6, 52 and 73% and faecal pellet production by 18, 51 and 86% with increasing WAF concentrations compared to controls. The phototoxic effect reduced primary production in the two highest WAF concentration treatments by 71 and 91%, respectively. This experiment contributes to the limited knowledge of acute sub-lethal effects of potential oil spills to the Arctic pelagic food web.
Crude oil accidentally spilled into the marine environment undergoes natural weathering processes that result in oil components being dissolved into the water column or present in particulate form as dispersed oil droplets. Oil components dissolved in seawater are typically considered as more bioavailable to pelagic marine organisms and the main driver of crude oil toxicity, however, recent studies indicate that oil droplets may also contribute. The adhesion of crude oil droplets onto the eggs of pelagic fish species may cause enhanced transfer of oil components via the egg surface causing toxicity during the sensitive embryonic developmental stage. In the current study, we utilized an oil droplet dispersion generator to generate defined oil droplets sizes/concentrations and exposed Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) to investigate if the potential for dispersed oil droplets to adhere onto the surface of eggs was species-dependent. The influence of a commercial chemical dispersant on the adhesion process was also studied. A key finding was that the adhesion of oil droplets was significantly higher for haddock than cod, highlighting key differences and exposure risks between the two species. Scanning electron microscopy indicates that the differences in oil droplet adhesion may be driven by the surface morphology of the eggs. Another important finding was that the adhesion capacity of oil droplets to fish eggs is significantly reduced (cod 37.3%, haddock 41.7%) in the presence of the chemical dispersant.
A series of alkyl bicarbamates supramolecular organogelators were synthesized with different structures and lengths of alkyl chains. The driving forces for the self-assembly of small molecules, including the intermolecular H bonding, p-p stacking and van der Waals interactions, played an important role in the formation of different 3D network structures, i.e., fibers, ribbons, sheets, and prisms. And a probable formation process of the gel networks was proposed. Furthermore, the phase-selective gelling performances were investigated for oil removal from aqueous solution. Interestingly, the gelling properties were found to be affected by the length and structure of alkyl chains, while some gelators with intermediate alkyl chain lengths could effectively gel all the tested oils from water surface within 15 min, such as Russian crude oil, diesel, gasoline, soybean oil, peanut oil, olive oil, cyclohexane, hexane and ethyl acetate. Advantageously, fast gelation, high rate of oil removal (>95%) and excellent oil retention rate (close to 100%) were realized in the recovery of oil spills from water surface. This kind of supramolecular gelators demonstrates good potential applications in the delivery or removal of organic pollution from oil/water mixtures.
There is significant risk associated with increased oil and gas exploration activities in the Arctic Ocean. This paper presents a probabilistic methodology for Ecological Risk Assessment (ERA) of accidental oil spills in this region. A fugacity approach is adopted to model the fate and transport of released oil, taking into account the uncertainty of input variables. This assists in predicting the 95th percentile Predicted Exposure Concentration (PEC95%) of pollutants in different media. The 5th percentile Predicted No Effect Concentration (PNEC5%) is obtained from toxicity data for 19 species. A model based on Dynamic Bayesian Network (DBN) is developed to assess the ecological risk posed to the aquatic community. The model enables accounting for the occurrence likelihood of input parameters, as well as analyzing the time-variable risk profile caused by seasonal changes. It is observed through the results that previous probabilistic methods developed for ERA can be overestimating the risk level.
The risk of oil spills is an ongoing societal concern. Whereas several decision support systems exist for predicting the fate and drift of spilled oil, there is a lack of accurate models for assessing the amount of oil spilled and its temporal evolution. In order to close this gap, this paper presents an online platform for the fast assessment of tanker grounding accidents in terms of structural damage and time-dependent amount of spilled cargo oil. The simulation platform consists of the definition of accidental scenarios; the assessment of the grounding damage and the prediction of the time-dependent oil spill size. The performance of this integrated online simulation environment is exemplified through illustrative case studies representing two plausible accidental grounding scenarios in the Gulf of Finland: one resulting in oil spill of about 50?t, while in the other the inner hull remained intact and no spill occurred.
Oil and gas exploration and marine transport in the Arctic region have put the focus on the ecological risk of the possibly exposed organisms. In the present study, the impacts of sea ice, extreme light regime, various polar region-specific physiological characteristics in polar cod (Boreogadus saida) and their effects on xenobiotic distribution and metabolism are studied. A Bayesian belief network is used to model individual fish toxicity. The enzyme activity in the fish liver and other pertinent organs is used as a proxy for cellular damage and repair and is subsequently linked to toxicity in polar cod. Seasonal baseline variation in enzyme production is also taken into consideration. The model estimates the probability of exposure concentration to cause cytotoxicity and circumvents the need to use the traditionally obtained No Observed Effect Concentration (NOEC). Instead, it uses biotransformation enzyme activity as a basis to estimate the probability of individual cell damages.
We simulate oil spills of 1500 and 4500m3/day lasting 14, 45, and 90days in the spawning grounds of the commercial fish species, Northeast Arctic cod. Modeling the life history of individual fish eggs and larvae, we predict deviations from the historical pattern of recruitment to the adult population due to toxic oil exposures. Reductions in survival for pelagic stages of cod were 0-10%, up to a maximum of 43%. These reductions resulted in a decrease in adult cod biomass of
This study presents a series of oil spill indexes for the characterization of physical and biological sensitivity in unsheltered coastal environments. The case study extends over 237 km of Lithuanian-Russian coastal areas subjected to multiple oil spill threats. Results show that 180 km of shoreline have environmental sensitivity index (ESI) of score 3. Natural clean-up processes depending on (a) shoreline sinuosity, (b) orientation and (c) wave exposure are favourable on 72 km of shoreline. Vulnerability analysis from pre-existing Kravtsovskoye D6 platform oil spill scenarios indicates that 15.1 km of the Curonian Spit have high impact probability. The highest seafloor sensitivity within the 20 m isobath is at the Vistula Spit and Curonian Spit, whereas biological sensitivity is moderate over the entire study area. The paper concludes with the importance of harmonized datasets and methodologies for transboundary oil spill impact assessment.