Assessment of PCB trajectories along French river corridors between 1945 and 2018

<p>The reconstruction and modelling of contamination trajectories in rivers is a key concern to investigate spatio-temporal impacts of long-term anthropogenic activities. This issue is highly significant for persistent organic pollutants, such as polychlorinated biphenyls (PCBs), known for their toxicity, their low degradation rates and their hydrophobic properties leading to their accumulation in sediments and biota. Increasingly produced and released worldwide from the 1930s to the 1970-1980s, PCBs were analysed in numerous studies dealing with river sediment quality. However, data syntheses are uncommon at the scale of large hydrosystems, and source-to-estuary approaches along rivers are still needed. Accordingly, we propose an original work integrating PCBs analyses on different solid matrices (sediment cores, bed and flood deposits, suspended particulate matters, and dredged sediments) originating from both research programmes and monitoring. Based on more than 1400 validated analyses, temporal trends of the PCB contamination were reconstructed since 1945 along the four main fluvial corridors in France (Rhône, Seine, Loire and Garonne Rivers). The relationships with socio-environmental factors were also deciphered by integrating hydrological and human spatio-temporal data (cumulative river discharge, population hot spots, urban and industrial surfaces). This work highlighted that the main contaminant trends were driven by regulation, but also by sediment transport and accidental releases (especially since the 1990s). In general, urban and industrial areas were the main contributors to the PCB contamination of rivers: around and downstream of Paris and Rouen (Seine River), Lyon and its “Chemical Valley” (Rhône River), Saint-Etienne and Nantes conurbations (Loire River), and probably downstream of Toulouse and Bordeaux (Garonne River). Relatively high concentrations persisted after the end of the PCB production due to chronic diffuse inputs and accidental releases, particularly on the Rhône River. Moreover, the estimation of specific fluxes revealed that up to 12 µg/m²/yr (i.e. 0.9 t/yr on average) of PCBs were brought by French rivers, especially by the Rhône, Seine and Loire Rivers (ranked in order of importance) to Western European seas since the 1970s.</p>

Mechanisms and Occurrence of Detonations in Vapor Cloud Explosions

Not all accidental releases of flammable gases and vapors create explosions. Most releases do not find an ignition source, and of those that do ignite, most of them result in deflagrations that generate low or moderate overpressures. Under some circumstances, however, it is possible for deflagration-to-detonation transition (DDT) to occur, and this can be followed by a propagating detonation that quickly consumes the remaining detonable cloud. In a detonable cloud, a detonation creates the worst accident that can happen. Because detonation overpressures are much higher than those in a deflagration and continue through the entire detonable cloud, the damage from a DDT event is more severe.This paper first provides a brief summary of our knowledge to date of the fundamental mechanisms of flame acceleration and DDT. This information is then contrasted to and combined with evidence of detonations (detonation markers) obtained from large-scale tests and actual large vapor cloud explosions (VCEs), including events at Buncefield (UK), Jaipur (India), CAPECO (Puerto Rico), and Port Hudson (US). The major conclusion from this review is that detonations did occur in prior VCEs in at least part of the VCE accidents. Finally, actions are suggested that could be taken to minimize detonation hazards.

Dispersion Modeling of Accidental Releases of Propane Gas

This paper investigates the impact of accidental release of propane gas in surrounding areas consequences of propane gas leak studying the negative effects on both the environment and individuals. Subject of the research is impact of accidental release of propane gas in in business zone “Ramići-Banja Luka”, Banja Luka. The ALOHA software has been used in this paper to modelling of propane release. The modelling was performed for an accidental release of 4,000 kg propane from unsheltered single storied for one hour. For a typical average atmospheric condition in location, this accidental propane release would cause a red zone of 101 metres (AEGL-3=33,000 ppm), orange zone of 159 metres (AEGL-2=17,000 ppm) and yellow zone of 324 metres (AEGL-1=5,500 ppm) to downwind from the source.

Using 2D and 3D Oil Spill Trajectory and Fate Models to Assess the Risk of Accidental Crude Oil Releases Along the Enbridge Line 3 Replacement Program Pipeline

The proposed Enbridge Line 3 Replacement Program would replace the aging pipeline from Hardisty, Alberta, Canada to Superior, Wisconsin, USA. For the Canadian route, an Ecological and Human Health Risk Assessment (EHHRA) was prepared for the National Energy Board (NEB) in Canada. In the United States, an Assessment of Accidental Releases (AAR) and the Supplemental Release Report were part of an Environmental Impact Statement (EIS) prepared for the Minnesota Public Utilities Commission (PUC) and Minnesota Department of Commerce, Energy Environmental Review and Analysis (DOC-EERA). Computational oil spill modeling was used to assess the predicted trajectory (movement), fate (behavior and weathering), and potential effects (impacts) associated with accidental releases of crude oil along the proposed pipeline. This modeling included the 2-dimensional OILMAPLand and 3-dimensional SIMAP models. A total of 64 hypothetical release scenarios were investigated to understand the range of potential trajectories, fates, and effects that may be possible from multiple product types (Bakken, Federated Crude, and Cold Lake Winter Blend), released at any location, under varying environmental conditions. Trajectory and fate modeling was used to predict the downstream movement and timing of oil, as well as the expected surface oil thickness, water column contamination, shoreline and sediment oiling, and proportion evaporated to the atmosphere. These results were then used to assess the potential environmental effects to demonstrate the variability of outcomes following a release under different release conditions.

Environmental Risk Analysis of Accidental Release From Onshore Oil Pipelines

Accidental releases of oil and oil products will cause extensive damage to environment, if timely and effective measures are not available. Predicting the consequences of spilled oil is of significant importance for emergency management. Although software for risk assessment of gas pipelines is very popular, few are available for hazardous liquid pipelines, due to the difference in behaviors of accidental releases of gases and liquids in the same situation. The major differences are that the spread of released oil is mainly affected by the topography of the land and may result in pollution of soil or waterways, while gas pipeline failure may form gas clouds or explosions and merely pose environmental pollution problems. An integrated model was developed in order to analyze the environmental consequences of spills from oil pipelines. The method presented in this paper allowed to predict the flow trajectory of released liquid from a pipeline and other relevant parameters, including the extent of spread of the oil and the proportion of release reaching any important location, such as a river, in any given topography. The methodology has been applied to a release, which occurred in Marshall, Michigan, in 2010. The results obtained are of the correct order of magnitude compared with realistic data. A case-study is presented and discussed to illustrate the features of the methodology. The results confirmed that the proposed model may be considered an important tool within a comprehensive approach to the management of risk related to onshore oil pipelines.