Time Of Spill Research Articles

Экспериментальные исследования формирования и горения водородно-воздушных смесей при проливах жидкого водорода и при воздействии на горение смесей водяных завес в частично ограниченном пространстве

Experimental studies of processes of liquid hydrogen spill and evaporation and the generation of explosive and fire-hazardous hydrogen-air mixtures in a partially confined space with varying degrees of confinement (varying degrees of leakage of openings) on a stand of 96 m3 volume have been conducted, which involved the ignition of mixtures with delayed and non-delayed inflammation and the measurement of overpressure of explosion; the impact of water screen on these processes have been studied as well. The experiments with duty torches feature rapid combustion of the mixture when the boundary of the generating explosive cloud approaches the area of installed burners, and the volume of the faintly glowing flame of the burning-out mixture rises to a significant height. For all the experiments, the overpressure in the shock wave generated by the flame was approximately the same, equal to 0.8–1.2 kPa. For experiments with delayed ignition, the generation and development of a visible hydrogen-air mixture cloud and its rapid combustion at the activation of burner flares were registered; the visible flame velocities reached 3,050 m/s. At the same time, the delayed ignition within the range of 1–3.2 s did not cause a significant increase of overpressure in the shock wave. Therefore, the specifics of the mixture combustion process in case of liquid hydrogen spills in a confined space are mainly determined by the conditions of mixture generation that significantly differ from the conditions of the generation of hydrogen-air mixture in free space. When hydrogen-air mixtures are exposed to a water screen after the ignition in a confined space, as well as in the air atmosphere, the processes of mixture combustion are activated due to initial combustible mixture flame turbulence. The turbulence of the initial combustible mixture flame is conducted on droplets acting as a periodic volumetric obstacle on the route of the flame front intensifying the flame. At the same time, water screens, with preemptive action, reduce the pressure in the shock wave by the time of the hydrogen spill.

A DiffeRential Evolution Adaptive Metropolis (DREAM)-based inverse model for continuous release source identification in river pollution incidents: Quantitative evaluation and sensitivity analysis

The identification of continuous pollution sources for rivers is of great concern for emergency response. Most studies focused on instantaneous river pollution sources and associated incidents. There is a dire need to address continuous pollution sources, as pollutant discharge may impose a major impact on the water ecosystem. Therefore, in this study, a novel inverse model is proposed to identify the continuous point sources in river pollution incidents that would estimate the source strength, location, release time, and spill time. The proposed inverse model combines the advanced DiffeRential Evolution Adaptive Metropolis (DREAM) algorithm and the forward transport advection-dispersion equation to infer the posterior probability distribution of source parameters for quantifying uncertainties. In addition, the performance of the DREAM-based model is compared with those of the Metropolis-Hastings (MH)-based and genetic algorithm (GA)-based models. The results show that the DREAM-based model performs accurately for both the hypothetical and the field tracer cases. The comparative analysis shows that the DREAM-based model performs better in saving computation time, improving the accuracy of results, and reconstructing pollutant concentrations. Observation errors significantly influence the accuracy of the identification results from the DREAM-based model. In addition, a comprehensive sensitivity analysis of the DREAM-based model is conducted. The identification results from the DREAM-based model are sensitive to the dispersion coefficient and river velocity. The accuracy of the inverse model could be improved by increasing the monitoring number and by monitoring locations closer to the spill site. The findings of this study can improve decision-making during emergency responses to sudden river pollution incidents.

Freshwater turtle populations as bioindicators following an oil spill: Delayed demographic changes reveal long-term impacts

Chronic, long-term impacts of oil spill disasters on wildlife often exceed short-term, highly visible mass mortalities and widespread oiling of individuals. Species with long lifespans, late maturation, and low recruitment rates are particularly vulnerable to long-term population-level impacts but can be useful as indicator species for ecosystem recovery. In 2010, one of the largest freshwater oil spills in the U.S. occurred in the Kalamazoo River, MI, when 3.2 million L of spilled oil impacted 56 km of river and associated wildlife. During cleanup and restoration efforts in 2010–2011, thousands of northern map turtles (Graptemys geographica) were captured, cleaned, and released. During 2019–2020 northern map turtles were captured to evaluate changes in the population size, demography, and size classes nine to ten years later.Population demography shifts occurred in the first few years after the spill in a species that otherwise exhibits minimal demographic fluctuation under “normal” conditions. In comparing demographic parameters at the time of the oil spill to values ∼ 10 years post-spill, a nearly 30% reduction in population size was detected, distribution of body size shifted to smaller males and females, and there was a shift in the population sex ratio between 2011 and 2019. There were also signals of failed recruitment in cohorts that would have hatched during the years immediately before and after the oil spill. These data suggest that beyond the direct mortality caused by the spill, declines in the estimated population size and shifts in the size distribution of northern map turtles are likely indicative of negative demographic impacts incurred following the 2010 oil spill and resulting cleanup.

Performance and emission characteristics of salviniaceae filiculoides aquatic fern oil and SiO2 nano additive biodiesel in CI engine

This present study deals the engine performance and emission of adding SiO2 nano additives in novel salviniaceae filiculoides aquatic fern biomass derived biodiesel. The primary aim of this present study was to investigate the effect of adding SiO2 nano additives into the Azolla Oil Methyl Ester (AZOME) as a sustainable biodiesel in the Compression Ignition (CI) engine and studying the engine performance and emission effects. The Azolla Oil Methyl Ester was prepared via transesterification process and blended with as-present diesel with various percentages. The SiO2 nano particles are mixed with AZOME using sonication. The test was conducted using a single cylinder Compression Ignition engine with different blends of AZOME biodiesel. The fuel was injected into the engine at different spill timings as 20°, 23°, and 26° Crank Angle (CA) before (b) Top Dead Centre (TDC). According to the results the break thermal efficiency of AZOME and its SiO2 blends were improved with spill timings. On compare with the conventional diesel the Injection Time (IT) of 23° b TDC and the average Brake Thermal Efficiency (BTE) of AZ20 fuel at the retarded spill timing of 20° was raised by 3.38%, while the AZ100 fuel at 20° b TDC is decreased by 0.9%. However the emission of AZ100 fuel found to be lesser due to the presence of SiO2 nano additives. Thus the addition of SiO2 nano additives along with aquatic biomass Azolla Oil Methyl Ester reduced the emission without affecting the engine performance.

Ultra-High Dose-Rate Carbon-Ion Scanning Irradiation with a Compact Type Medical Synchrotron toward FLASH Research

<h3>Purpose/Objective(s)</h3> To establish an irradiation system to enable the ultra-high dose-rate (uHDR; FLASH) scanned carbon-ion irradiation with a compact type medical synchrotron. <h3>Materials/Methods</h3> After technical adjustments of the accelerator operation parameters, the medical synchrotron extracted ≥1.0 × 10⁹ carbon-ions (2.0 nC/spill) at 208.3 MeV/u (86 mm in range) within a maximum 100 ms. The uHDR carbon-ion beam delivery system was designed to prevent damage to monitors in the nozzle due to the uHDR beam by avoiding passage through the nozzle. The dose amount was adjusted by the extraction time of the total spill with a function generator. The carbon-ion beam was scanned once to create a field within the extraction time. Advanced Markus chamber and radiographic film were used to measure the absolute dose and the field size respectively, at a plateau depth. Operation voltage of the chamber was set to 400 V at the uHDR. <h3>Results</h3> The FLASH irradiation utilizing beam scanning was confirmed with a dose of 5.4 Gy (homogeneity of ±2%) for the beam in a volume of at least 16 mm × 16 mm in a square field and a corresponding dose-rate of 95 Gy/s (± 1%). The dose was changed to about 0.7, 1.5, 2.9 Gy for the dose-rate and the field size. Details of the results are shown in Table1. <h3>Conclusion</h3> The FLASH dose-rates >40 Gy/s at different dose levels were achieved in a useful field size for research created by the scanned carbon-ion beams with the compact type medical synchrotron. This study reported promising beam characteristics of uHDR scanned carbon-ion beams, at different dose levels, and can be used for further investigation of carbon-ion FLASH research. The dose and dose-rate established with the uHDR irradiation system can be applied in biological experiments.

Numerical Study on the Influence of Model Uncertainties on the Transport of Underwater Spilled Oil.

Oil pollution influences marine biology, ecology, and regional sustainable development capacity, but model uncertainties limit the ability of the numerical model to accurately predict the transport and fate of the underwater oil spill. Based on a three-dimensional underwater oil spill model validated by satellite images of the oil slick at the sea surface, the Penglai 19-3 oil spill accident in the Bohai Sea was simulated; in addition, several sensitivity experiments were set up to investigate the influence of model uncertainties in the background wind, current, start time of the oil spill, and spill site on the transport of underwater spilled oil in the Penglai 19-3 oil spill accident. The experimental results indicate that the uncertainty in the background wind has a certain impact on the simulated centroid position at the sea surface, and little effect on the simulated underwater results, while the uncertainty in the background current has a significant influence on the transport of the underwater spilled oil both at the sea surface and underwater. An uncertainty of 24 h in the start time of the oil spill can cause more than 1 time larger than the benchmark case displacement of the oil spill centroid point and sweeping area at the sea surface, as the periodic tidal current is the main constituent of the ocean current in the Bohai Sea. The uncertainty in the spill site has a large influence on the final position of the oil spill centroid point, but the oil spill trajectories do not intersect with each other within 48 h, which makes it possible to identify the oil spill platform from the actual observations. The influence of uncertainties in the important model inputs and key model parameters on the transport of underwater spilled oil in the Penglai 19-3 oil spill accident is evaluated for the first time, which is of substantial significance for improving the prediction accuracy of the transport and fate of underwater oil spills.

Using satellite-based AOD and ground-based measurements to evaluate the impact of the DWH oil spill on coastal air quality

The 2010 DWH disaster generated atmospheric pollutants of health concern which reached the Gulf Coast. This study evaluated whether changes in coastal air quality due to the disaster were captured by aerosol optical depth (AOD) estimated using satellite data and by ground-based monitoring of air pollution, including fine particulate matter ≤2.5 μm in aerodynamic diameter (PM2.5), benzene and naphthalene. Mean monthly AOD levels were higher in May 2010 [during oil spill time], (mean AOD = 0.355), than for the prior (mean AOD = 0.258) and following years (mean AOD = 0.252) (p < 0.05). PM2.5 concentrations and AOD were significantly correlated (R2 = 0.59, p < 0.05), for one study area. Elevated PM2.5, benzene, and naphthalene concentrations coincided with downwind directions from the location of the oil slicks. A fully-coupled oil fate and transport atmospheric transport model of oil spill emissions, integrated with AOD and more extensive ground-based measurements, is recommended to predict coastal population exposures during oil spills.

Developing an accurate model of spot-scanning treatment delivery time and sequence for a compact superconducting synchrocyclotron proton therapy system

BackgroundA new compact superconducting synchrocyclotron single-room proton solution delivers pulsed proton beams to each spot through several irradiation bursts calculated by an iterative layer delivery algorithm. Such a mechanism results in a new beam parameter, burst switching time (BST) in the total beam delivery time (BDT) which has never been studied before. In this study, we propose an experimental approach to build an accurate BDT and sequence prediction model for this new proton solution.MethodsTest fields and clinical treatment plans were used to investigate each beam delivery parameter that impacted BDT. The machine delivery log files were retrospectively analyzed to quantitatively model energy layer switching time (ELST), spot switching time (SSWT), spot spill time (SSPT), and BST. A total of 102 clinical IMPT treatment fields’ log files were processed to validate the accuracy of the BDT prediction model in comparison with the result from the current commercial system. Interplay effect is also investigated as a clinical application by comparing this new delivery system model with a conventional cyclotron accelerator model.ResultsThe study finds that BST depends on the amount of data to be transmitted between two sequential radiation bursts, including a machine irradiation log file of the previous burst and a command file to instruct the proton system to deliver the next burst. The 102 clinical treatment fields showed that the accuracy of each component of the BDT matches well between machine log files and BDT prediction model. More specifically, the difference of ELST, SSWT, SSPT, and BST were (− 3.1 ± 5.7)%, (5.9 ± 3.9)%, (2.6 ± 8.7)%, and (− 2.3 ± 5.3)%, respectively. The average total BDT was about (2.1 ± 3.0)% difference compared to the treatment log files, which was significantly improved from the current commercial proton system prediction (58 ± 15)%. Compared to the conventional cyclotron system, the burst technique from synchrocyclotron effectively reduced the interplay effect in mobile tumor treatment.ConclusionAn accurate BDT and sequence prediction model was established for this new clinical compact superconducting synchrocyclotron single-room proton solution. Its application could help users of similar facilities better assess the interplay effect and estimate daily patient treatment throughput.

Association of Deepwater Horizon Oil Spill Response and Cleanup Work With Risk of Developing Hypertension

Exposure to hydrocarbons, fine particulate matter (PM2.5), and other chemicals from the April 20, 2010, Deepwater Horizon disaster may be associated with increased blood pressure and newly detected hypertension among oil spill response and cleanup workers. To determine whether participation in cleanup activities following the disaster was associated with increased risk of developing hypertension. This cohort study was conducted via telephone interviews and in-person home exams. Participants were 6846 adults who had worked on the oil spill cleanup (workers) and 1505 others who had completed required safety training but did not do cleanup work (nonworkers). Eligible participants did not have diagnosed hypertension at the time of the oil spill. Statistical analyses were performed from June 2018 to December 2021. Engagement in cleanup activities following the Deepwater Horizon oil spill disaster, job classes, quintiles of cumulative total hydrocarbons exposure level, potential exposure to burning or flaring oil, and estimated PM2.5 were examined. Systolic and diastolic blood pressure measurements were collected during home exams from 2011 to 2013 using automated oscillometric monitors. Newly detected hypertension was defined as antihypertensive medication use or elevated blood pressure since the spill. Log binomial regression was used to calculate prevalence ratios (PR) and 95% CIs for associations between cleanup exposures and hypertension. Multivariable linear regression was used to estimate exposure effects on continuous blood pressure levels. Of 8351 participants included in this study, 6484 (77.6%) were male, 517 (6.2%) were Hispanic, 2859 (34.2%) were non-Hispanic Black, and 4418 (52.9%) were non-Hispanic White; the mean (SD) age was 41.9 (12.5) years at enrollment. Among workers, the prevalence of newly detected hypertension was elevated in all quintiles (Q) of cumulative total hydrocarbons above the first quintile (PR for Q3, 1.29 [95% CI, 1.13-1.46], PR for Q4, 1.25 [95% CI, 1.10-1.43], and PR for Q5, 1.31 [95% CI, 1.15-1.50]). Both exposure to burning and/or flaring oil and gas (PR, 1.16 [95% CI, 1.02-1.33]) and PM2.5 from burning (PR, 1.26 [95% CI, 0.89-1.71]) for the highest exposure category were associated with increased risk of newly detected hypertension, as were several types of oil spill work including cleanup on water (PR, 1.34 [95% CI, 1.08-1.66]) and response work (PR, 1.51 [95% CI, 1.20-1.90]). Oil spill exposures were associated with newly detected hypertension after the Deepwater Horizon disaster. These findings suggest that blood pressure screening should be considered for workers with occupational hydrocarbon exposures.

The 2019 northeast Brazil oil spill: scenarios.

During the last quarter of 2019, the beaches, mangroves, and estuaries of Northeast Brazil received an unprecedented volume of crude oil from the sea, which became the worst environmental disaster ever to reach the Brazilian coast. The oil, having reached the shores completely unnoticed, left both society and government agents completely clueless on (i) where the oil was coming from; (ii) how much oil was still in the ocean to reach the shorelines; and (iii) which beaches were going to be affected next! By exploring remote sensing data and ocean numerical modeling, along with oil dispersion chemistry on sea water, this study investigates the possible origin and path of the spill and whether it could have been detected from space. The oil dispersion modeling simulations performed for this investigation revealed a possible region and timing of the oil spill, also indicating the likelihood of it being advected toward the shoreline under the ocean surface.

Stormwater Runoff Modelling in an Urban Catchment to Plan Risk Management for Contaminant Spills for Stormwater Harvesting

Water quality is a key consideration for urban stormwater harvesting via aquifers. This study assessed catchment spill management options based on a calibrated dynamic wave routing model of stormwater flow in an urban catchment. The study used measured travel times, pluviometer and gauging station observations from 21 storms to calibrate a stormwater model to simulate transport of pollutants from spill locations to the point of harvest. The simulations considered the impact of spill locations, spill durations, storm intensities and storm durations on the pollutant concentration at the point of harvest and travel time of a pollutant spill to the harvesting point. During dry weather, spill events travelled slower than spills occurring during wet weather. For wet weather spills, the shortest travel times tended to occur in higher intensity storms with shorter duration, particularly when a spill occurred in the middle of the storm. Increasing the intensity of rainfall reduced the peak concentration of pollutant at the harvest point via dilution, but it also reduced the time of travel. On a practical level, due to the short response times in urban catchments, management of spills should be supported by automated detection/diversion systems to protect stormwater harvesting schemes.

Feasibility study of 3D time-reversal reconstruction of proton-induced acoustic signals for dose verification in the head and the liver: A simulation study.

In vivo range and dose verification based on proton-induced acoustics (protoacoustics) is potentially a useful tool for proton therapy. Built upon our previous study with two-dimensional reconstruction, the time reversal (TR) method was extended to three-dimensional (3D) and evaluated at two treatment sites (head and liver) through simulation, with the emphasis on a number of aspects such as increased spatial coverage, computational workload, and signal interference among slices. Two mono-energetic pencil beams were modeled in each site. The k-Wave toolbox was used to investigate the propagation and TR reconstruction of acoustic waves. The performance was quantitatively assessed based on mean square error (MSE) for dose verification and Bragg peak localization error (ΔBP ) for range verification, with regard to five parameters: number of sensors, sampling duration, sampling timestep, spill time, and noise level. The respective impacts of five parameters are examined. Under the optimum setting, the achievable ΔBP can be limited within 1 voxel (voxel size: 3×3×3mm3 ) and the achievable MSE can be limited below 0.02, for the head case (56sensors) and the liver case (204sensors), respectively. The feasibility of range and dose verification utilizing the 3D TR method is demonstrated, as the very first step. In spite of several challenges unique to the 3D case (spatial coverage, computational workload, and signal interference among slices, etc.), promising performance is found and can be further improved through optimizing the deployment of sensors. The proposed approach may find potential use in several applications: beam diagnostics, in vivo dosimetry, and treatment monitoring.

A food chain-based ecological risk assessment model for oil spills in the Arctic environment

This paper investigates the linkage between the acute impacts on apex marine mammals with polar cod responses to an oil spill. It proposes a Bayesian network-based model to link these direct and indirect effects on the apex marine mammals. The model predicts a recruitment collapse (for the scenarios considered), causing a higher risk of mortality of polar bears, beluga whales, and Narwhals in the Arctic region. Whales (adult and calves) were predicted to be at higher risk when the spill was under thick ice, while adult polar bears were at higher risk when the spill occurred on thin ice. A spill over the thick ice caused the least risk to whale and adult polar bears. The spill's timing and location have a significant impact on the animals in the Arctic region due to its unique sea ice dynamics, simple food web, and short periods of food abundance.

Multi-stressor Effects of Ultraviolet Light, Temperature, and Salinity on Louisiana Sweet Crude Oil Toxicity in Larval Estuarine Organisms.

When oil is spilled into the environment its toxicity is affected by abiotic conditions. The cumulative and interactive stressors of chemical contaminants and environmental factors are especially relevant in estuaries where tidal fluctuations cause wide variability in salinity, temperature, and ultraviolet (UV) light penetration, which is an important modifying factor for polycyclic aromatic hydrocarbon (PAH) toxicity. Characterizing the interactions of multiple stressors on oil toxicity will improve prediction of environmental impacts under various spill scenarios. This study examined changes in crude oil toxicity with temperature, salinity, and UV light. Oil exposures included high-energy, water-accommodated fractions (HEWAFs) and thin oil sheens. Larval (24-48h post hatch) estuarine species representing different trophic levels and habitats were evaluated. Mean 96h LC50 values for oil prepared as a HEWAF and tested under standard conditions (20 ppt, 25°C, No-UV) were 62.5µg/L tPAH50 (mud snails), 198.5µg/L (grass shrimp), and 774.5µg/L (sheepshead minnows). Thin oil sheen 96h LC50 values were 5.3µg/L tPAH50 (mud snails), 14.7µg/L (grass shrimp), and 22.0µg/L (sheepshead minnows) under standard conditions. UV light significantly increased the toxicity of oil in all species tested. Oil toxicity also was greater under elevated temperature and lower salinity. Multi-stressor (oil combined with either increased temperature, decreased salinity, or both) LC50 values were reduced to 3µg/L tPAH50 for HEWAFs and < 1.0µg/L tPAH50 for thin oil sheens. Environmental conditions at the time of an oil spill will significantly influence oil toxicity and organismal response and should be taken into consideration in toxicity testing and oil spill damage assessments.

Monitoring chemical compositional changes of simulated spilled Brazilian oils under tropical climate conditions by multiple analytical techniques

To comprehensively understand the chemical changes over time of spilled oils subject to tropical climate conditions and the active weathering processes, a spill simulation experiment was conducted along 210 days with two distinct Brazilian oils (19 and 24 API) under irradiation and non-irradiation of sunlight. Isoprenoids and n-alkanes showed a great loss after 40 days for both oils under the two conditions due to evaporation. Diagnostic ratios of saturated biomarkers showed no changes, whereas the polycyclic aromatic hydrocarbons had a decreasing concentration under both conditions mainly due to evaporation. Furthermore, oxygenated polar compounds produced by photooxidation were investigated by ESI(−) FT-ICR MS and showed changes only for the oils exposed to sunlight irradiation. Based on the observed polar compositional changes, new parameters are suggested using heteroatom classes to estimate oil spill time under tropical conditions: NO3/NO2; NO3/(NO + NO2); ∑NOx/N1; (O4 + O3)/(O2 + O1); O4/(O2 + O1); and O3/O2.

Numerical Simulation Study on the Effects of Oil Spill Diffusion in The Qitou Sea Area

A two-dimensional hydrodynamic mathematical model of the sea area near the Qitou sea area was established by using MIKE21 hydrodynamic module, and the tidal level, flow velocity and direction simulated by the hydrodynamic model were verified according to the measured data. Based on MIKE21 hydrodynamic model and particle tracking module, a mathematical model of oil spill diffusion centered on the sea area of Qitou was established, and the influence range of oil spill under six different working conditions and the time of oil spill reaching the main sensitive area near The sea area of Qitou were simulated. The analysis shows that tidal current and wind are the main factors affecting the diffusion process of oil spill in The Qitou sea. The calculation results show the influence area of oil spill 24 hours after the occurrence of the accident and the time when the oil spill reaches the main sensitive area in The sea area of Qitou, which has a certain guiding role in dealing with the offshore oil spill pollution and formulating the emergency treatment plan of oil spill accident in the sea area of Qitou.

An Operational Supporting System for Oil Spill Emergencies Addressed to the the Italian Coast Guard

Oil spill models are used to simulate the evolution of an oil slick that occurs after an accidental ship collision, malfunctioning of oil extraction platforms, or illegal discharges intentionally released by ships into the marine environment. We present an integrated operational oil spill prediction system that improves capacities in preventing and mitigating maritime risks from oil spills. The objective is to provide forecast information about the transport and the fate of a hypothetical oil spill under Nearly-Real Time hydrodynamic conditions in the western and central Mediterranean Sea. This complex forecast system is developed in the framework of the project SOS-Piattaforme &amp; Impatti Off-Shore to the needs of Italian Coast Guard and other institutions, such as the Ministry of the Environment. This service has been operational since July 2020. The innovative aspect of this work is a graphical user interface (the GUI), which allows to select properties, time, and location of a potential oil spill and show the evolution of oil slick concentration and oil fate parameters. This platform represents the first component of a future Decision Support System aimed to identify the risk assessment of oil spills in order to better manage emergencies and minimize economic damages.

Spread characteristics of hydrogen vapor cloud for liquid hydrogen spill under different source conditions

During the storage and transportation processes of liquid hydrogen, the accidental spill could cause great damage. Mixture multiphase model and Realizable k-ε model are adopted to predict the spread of hydrogen cloud in liquid hydrogen spill. Effects of source parameters on spread characteristics of hydrogen cloud, including spill rate and liquid mass fraction, are analyzed. For the spill with various spill rates, the cases of fixed spill amount or spill time are considered in view of emergency response strategy to the spill source. The results show that the spreads of hydrogen vapor cloud in downwind and vertical directions can be both promoted by increasing the spill rate. When the total spill amount is fixed, the volume ratio of detonation cloud to flammable cloud at the spill termination instant increases firstly and then decreases with spill rate, due to the combined effects of near-source turbulence and mixing time with air. When the source is terminated after a fixed spill period, the detachment distances of flammable vapor cloud keep almost constant for the spill rates below 9.52 kg/s, while the cloud is more lifted if further increasing the spill rate, during which the role of the near-source turbulence overweighs that of the spill amount. The upward movement of flammable vapor cloud is promoted by increasing liquid mass fraction, with increased height and reduced detachment distance. The work provides a guidance to risk assessment and safe handling of liquid hydrogen.

Numerical simulation of the environmental impact of oil spill in the Liuheng Island of Zhoushan City

At present, numerical models of 2D tidal current and oil spill have been widely used in simulating the diffusion and spread of spilled oil. Thus, this paper adopts the MIKE21_FM hydrodynamic model, and establishes a 2D tidal current dynamic model based on unstructured meshes in the Liuheng Island of Zhoushan city. After verification by the measured data, it can be found that this model can reflect the hydrodynamic characteristics perfectly, and provide sufficient hydrodynamic conditions for the simulation of oil spill. Based on that, the MIKE21/3 OS model is applied for predicting the risk of oil spill. Accordingly, 8 working conditions are simulated to track the spread and sweeping area of spilled oil. The results show that both oil spill time, tidal current and wind direction can affect oil diffusion, while wind direction is the most dominant factor. Moreover, the sweeping area increases gradually with time, and the maximum area reaches 2018.95 km2 after 72 hours at ebb tide under the wind direction of WNW.

Simulating crude oil exposure, uptake and effects in North Atlantic Calanus finmarchicus populations

A simulation model framework (SYMBIOSES) that includes a 3-dimensional ocean physics and biology model and a model for transport and fate of oil was used to investigate the potential for bioaccumulation and lethal/sublethal effects of oil components in the copepod Calanus finmarchicus in the Lofoten–Vesterålen archipelago of Norway. The oil model is coupled with the biology model by way of a bioaccumulation model, from which mortality and reduction in reproduction are calculated via a total body burden (TBB). The simulation results indicate that copepod body burden levels are affected by the spill type (surface spill, subsea blowout) and the spill timing (spring, autumn). The effects of oil component bioaccumulation on the copepod population for all scenarios are small, though greatest in the subsea blowout scenarios. We attribute this to the limited spatial and temporal overlap between copepods and oil in the environment simulated by the model. The coupling of the processes of oil transport, bioaccumulation/excretion and the associated effects are discussed in the context of the model framework and with a view towards applications for Ecological Risk Assessment (ERA).