Trajectory, fate, and magnitude of continental microplastic loads to the inner shelf: A case study of the world's largest coastal shallow lagoon.

The Patos Lagoon estuary is a highly significant ecosystem where freshwater from a vast and densely populated area continuously flows into the Atlantic Ocean by coastal plumes, exporting not only freshwater but also sediment, nutrients, plastics, and other contaminants. In this work, numerical modeling tools together with field data were used to assess for the first time the capacity of the coastal plume to export microplastics (MPs) to the inner shelf under different hydrodynamic conditions. Two field surveys were conducted during plume events to quantify MP concentrations and validate the model approach. A bottom-up approach was employed to estimate the potential MP export from the estuary's domain to the Atlantic Ocean. MP concentration in surface plume waters ranged from 0.20 items m-3 to 1.37 items m-3, confirmed by FTIR as synthetic polymers in a 90 %, being Polypropylene (PP) and Polyethylene (PE) the most abundant in a 73 %. The accumulation pattern was observed on the plume's frontal system, consistent with simulation results. The estimated average MP potential export rate attained 9.0 million items day-1 during moderate plume events and 47.5 million items day-1 during high discharge plume events. Strong discharge events, coupled with intense northeast winds, facilitated rapid southwestward export of MPs. Conversely, moderate to weak discharge events retained MPs closer to the estuary's mouth, enabling either longer trajectories or earlier deposition. Significant MP accumulation hotspots were identified in the gyre between the jetties and Cassino beach, as well as in the saline front within the plume boundaries. These accumulation zones may function as reservoirs for MP particles, potentially posing threats to local ecosystems. Understanding these dynamics is crucial for ongoing monitoring efforts to assess potential harmful interactions over time.

Simulation Analysis on the Characteristics of Aerosol Particles to Inhibit the Infrared Radiation of Exhaust Plumes.

Aerosol infrared stealth technology is a highly effective method to reduce the intensity of infrared radiation by releasing aerosol particles around the hot exhaust plume. This paper uses a Computational Fluid Dynamics (CFD) two-phase flow model to simulate the exhaust plume fields of three kinds of engine nozzles containing aerosol particles. The Planck-weighted narrow spectral band gas model and the Reverse Monte Carlo method are used for infrared radiation transfer calculations to analyze the influencing factors and laws for the suppression of the infrared radiation properties of exhaust plumes by four typical aerosol particles. The simulation calculation results show that the radiation suppression efficiency of aerosol particles on the exhaust plume reaches its maximum value at a detection angle (ϕ) of 0° and decreases with increasing ϕ, reaching its minimum value at 90°. Reducing the aerosol particle size and increasing the aerosol mass flux can enhance the suppression effect. In the exhaust plume studied in this paper, the radiation suppression effect is best when the particle size is 1 µm and the mass flux is 0.08 kg/s. In addition, the inhibition of aerosol particles varies among different materials, with graphite having the best inhibition effect, followed by H2O, MgO, and SiO2. Solid particles will increase the radiation intensity and change the spectral radiation characteristics of the exhaust plume at detection angles close to the vertical nozzle axis due to the scattering effect. Finally, this paper analyzed the suppression effects of three standard nozzle configurations under the same aerosol particle condition and found that the S-bend nozzle provides better suppression.

A Gaussian-plume based Monte Carlo method for calculating radiation dose in the near field of buildings.

A Monte Carlo (MC) programme was written using the dose point kernel method to calculate doses in the roof zone of a building from nearby releases of radioactive gases. A Gaussian Plume Model (GPM) was parameterised to account for near-field building effects on plume spread and reflection from the roof. Rooftop recirculation zones and building-generated plume spread effects were accounted in a novel Dual Gaussian Plume (DGP) formulation used with the MC model, which allowed for the selection of angle of approach flow, plume release height in relation to the building and position of the release point in relation to the leading edge of the building. Three-dimensional wind tunnel concentration field data were used for the parameterisation. The MC code used the parameterised concentration field to calculate the contributions to effective dose from inhalation, cloud immersion from positron/beta particles, and gamma-ray dose for a wide range of receptor dose positions in the roof zone, including receptor positions at different heights above the roof. Broad trends in predicted radiation dose with angle of approach flow, release position in relation to the building and release height are shown. Alternative approaches for the derivation of the concentration field are discussed.

Increased methane emissions from oil and gas following the Soviet Union's collapse.

Global atmospheric methane concentrations rose by 10 to 15 ppb/y in the 1980s before abruptly slowing to 2 to 8 ppb/y in the early 1990s. This period in the 1990s is known as the "methane slowdown" and has been attributed in part to the collapse of the former Soviet Union (USSR) in December 1991, which may have decreased the methane emissions from oil and gas operations. Here, we develop a methane plume detection system based on probabilistic deep learning and human-labeled training data. We use this method to detect methane plumes from Landsat 5 satellite observations over Turkmenistan from 1986 to 2011. We focus on Turkmenistan because economic data suggest it could account for half of the decline in oil and gas emissions from the former USSR. We find an increase in both the frequency of methane plume detections and the magnitude of methane emissions following the collapse of the USSR. We estimate a national loss rate from oil and gas infrastructure in Turkmenistan of more than 10% at times, which suggests the socioeconomic turmoil led to a lack of oversight and widespread infrastructure failure in the oil and gas sector. Our finding of increased oil and gas methane emissions from Turkmenistan following the USSR's collapse casts doubt on the long-standing hypothesis regarding the methane slowdown, begging the question: "what drove the 1992 methane slowdown?"

The critical mixed transport process in remediation agent radial injection into contaminated aquifer plumes.

Accurately depicting the subsurface mixing of radially injected remediation agents with contaminated plumes remains paramount yet challenging for understanding and simulating reactive transport. To address this, the present research employed the mixing dynamics of a potassium permanganate plume injected into a pre-existing contaminated plume. Through combining colour deconvolution and thresholding, we effectively isolated local mixing values within the Gaussian annular narrow mixing zone from the noise of mixed double-plume images. Key findings revealed increasing injection rate promotes plume mixing while adding xanthan gum to increase fluid viscosity moderates interface mixing, reducing mixing zone width by 25.3% and 37.4% for 100 mg/L and 400 mg/L xanthan gum, respectively. Grain size is pivotal, with a 30% increase in mixing areas observed in coarse-grained sands over medium-grained sands. Balancing sufficient mixing and preventing contaminated plume growth is essential for effective remediation. Injection rates below 5 mL/min may suppress contaminated plume expansion, albeit at the possible cost of protracted remediation durations. For the attainment of optimal remediation, it's imperative to harmonize robust mixing processes with the mitigation of contaminated plume expansion - a balance that adding xanthan gum during the initial injection phase seems poised to achieve (xanthan gum optimized the average mixing index (AMI)). These findings provide valuable insights into groundwater plume mixing, supporting effective remediation strategies.

Nanoparticle Concentration in Surgical Plume During Tonsillectomy: A Comparison of Four Techniques.

OBJECTIVE: Surgical plume has known potential occupational health hazards. This study compares nanoparticle concentrations in surgical plumes generated between different pediatric tonsillectomy surgical techniques and assesses the efficacy of mitigation measures. METHODS: This is a cross-sectional study performed at a tertiary care academic center. Extracapsular or intracapsular tonsillectomy was performed in 60 patients using four techniques and in 10 additional patients using mitigation measures. Two nanoparticle counters were used to measure particulate concentrations: CPC™ and DiSCmini™. Tonsillectomy techniques included: (1) microdebrider (MD), (2) Bovie with manual suctioning by an assistant (B), (3) Bovie with built-in smoke evacuation system (BS), and (4) Coblator™ (CB). An additional Yankauer suction was used in the mitigation groups (BSY) and (CBY). Comparative analysis was performed using one-way ANOVA on ranks and pairwise comparisons between the groups. RESULTS: The mean concentrations (particles/cm3) and coefficient of variants for the DiSCmini particulate counter were MD: 5140 (1.6), B: 30700 (1.5), BS: 25001 (0.8), CB: 54814 (1.7), CBY: 2395 (1.3) and BSY: 11552 (1.0). Mean concentrations for the CPC particulate counter were MD: 1223 (1.4), B: 3405 (0.7), BS: 5002 (0.9), CB: 13273 (1.0), CBY: 1048 (1.2) and BSY: 3046 (0.6). The lowest mean concentrations were noted in cases using MD and the highest in cases using CB. However, after mitigation, CBY had the lowest overall levels. CONCLUSION: Tonsillectomy technique does impact the levels of nanoparticles emitted within the surgical plume, which may present an occupational hazard for operating room personnel. LEVEL OF EVIDENCE: 3 Laryngoscope, 134:2444-2448, 2024.

Chemical constituents, viable micro-organism and malignant cell content in ultrasonic scalpel plume: A literature review.

PURPOSE: To identify all published data on the chemical, micro-organism and malignant cell contents of ultrasonic scalpel plume, if any, and on any clinical implications of the contents on patients and operating staff. METHODS: Searches were conducted aiming to identify all published evidence on the chemical constituents, presence/absence of viable micro-organisms and malignant cells in ultrasonic scalpel plume. Attempts were made to source unpublished industry data. RESULTS: There is evidence from human and in vitro studies of the presence of a range of harmful, and some human carcinogenic, chemicals within ultrasonic plume, mostly at very low concentrations. Any clinical relevance of this has not been studied. There is evidence from experimental studies of the presence of hepatitis virus, human coronavirus and human papillomavirus material within ultrasonic plume. Any clinical effect of this has not been studied. There is conflicting evidence from combined in vitro and mouse model studies of the presence of viable malignant cells within ultrasonic plume. Any clinical relevance of this has also not been studied. CONCLUSION: Overall, relatively little research into the plume has been published, and further study is required to more clearly delineate any potential risk to patients, surgeons and other theatre staff. Current safety recommendations are discussed.

Numerical analysis of dispersion characteristics of underwater gas-oil two-phase leakage process.

Fatigue failure, third-party destruction and internal corrosion may easily trigger gas and oil leakage during the operation of submarine multiphase pipelines. In order to analyze the underwater gas-oil plume development and migration law, a 3D model based on coupled Eulerian-Lagrangian numerical approach is proposed. The model is validated by laboratory experiment and the dynamic dispersion process of gas-oil plume in a large scale shallow sea environmental is further explored. Influencing factors such as leak location, leak size and water depth, flow pattern are investigated. The simulated results show that leak location affects the gas-oil plume migration behaviors by influencing the leakage amount. Water depth significantly affects gas-oil migration and the separation of gas plume and oil plume is gradually apparent as water depth increases. This study fills in the gap of ignoring the influence of flow pattern previously and is expected to help build more accurate emergency response guidelines.

Active smelling in the American cockroach.

Motion plays an essential role in sensory acquisition. From changing the position in which information can be acquired to fine-scale probing and active sensing, animals actively control the way they interact with the environment. In olfaction, movement impacts the time and location of odour sampling as well as the flow of odour molecules around the olfactory organs. Employing a detailed spatiotemporal analysis, we investigated how insect antennae interact with the olfactory environment in a species with a well-studied olfactory system - the American cockroach. Cockroaches were tested in a wind-tunnel setup during the presentation of odours with different attractivity levels: colony extract, butanol and linalool. Our analysis revealed significant changes in antennal kinematics when odours were presented, including a shift towards the stream position, an increase in vertical movement and high-frequency local oscillations. Nevertheless, the antennal shifting occurred predominantly in a single antenna while the overall range covered by both antennae was maintained throughout. These findings hold true for both static and moving stimuli and were more pronounced for attractive odours. Furthermore, we found that upon odour encounter, there was an increase in the occurrence of high-frequency antennal sweeps and vertical strokes, which were shown to impact the olfactory environment's statistics directly. Our study lays out a tractable system for exploring the tight coupling between sensing and movement, in which antennal sweeps, in parallel to mammalian sniffing, are actively involved in facilitating odour capture and transport, generating odour intermittency in environments with low air movement where cockroaches dwell.

Emission Measurements on a Large Sample of Heavy-Duty Diesel Trucks in China by Using Mobile Plume Chasing.

Real-world heavy-duty diesel trucks (HDTs) were found to emit far more excess nitrogen oxides (NOX) and black carbon (BC) pollutants than regulation limits. It is essential to systematically evaluate on-road NOX and BC emission levels for mitigating HDT emissions. This study launched 2109 plume chasing campaigns for NOX and BC emissions of HDTs across several regions in China from 2017 to 2020. It was found that NOX emissions had limited reductions from China III to China V, while BC emissions of HDTs exhibited high reductions with stricter emission standard implementation. This paper showed that previous studies underestimated 18% of NOX emissions in China in 2019 and nearly half of the real-world NOX emissions from HDTs (determined by updating the emission trends of HDTs) exceeded the regulation limits. Furthermore, the ambient temperature was identified as a primary driver of NOX emissions for HDTs, and the low-temperature penalty has caused a 9-29% increase in NOX emissions in winter in major regions of China. These results would provide important data support for the precise control of the NOX and BC emissions from HDTs.

Applications of bubble curtains in marine oil spill containment: Hydrodynamic characteristics, applications, and future perspectives.

Although the marine oil spill pollution issue does not bring us to flock in droves as the new emerging oceanic techniques like wave energy converters, remote operated vehicle (ROV), blue ammonia and green hydrogen, the huge pollution risks of the marine oil spills caused by man-made intentional discharge, old equipment, accidental leakage, war and other aspects should arouse our sufficient attention and concern. As the primary countermeasure of emergency response to a marine oil spill, rapid & efficient oil containment is crucial to limit the pollution scope and the subsequent recovery and treatment. Here, we summarized the existing investigations on oil-spill containment with a marked emphasis on the applications of bubble curtains and their working mechanisms. The critical research progress and trends about the remediation techniques and the application of bubble curtains in marine environments were briefly introduced. The article thoroughly analyzed the basic working mechanism of the bubble curtains in oil spill containment, the technical difficulties of the existing methods, the potential application prospects of coupling with the traditional oil containment booms and the critical scientific problems to be studied in the future. Regarding the issues involving insufficient oil retention performance and inconvenient deployment of the existing traditional oil boom under complex and variable sea conditions, the performance and structural optimization of bubble curtain enhanced oil containment boom will get the top priority in developing the next-generation oil containment techniques.

Investigation of the Contents of the Stack Emissions of Iron Ore Sinter Plants With and Without Bag Filter.

This investigation aims to identify the reasons for the plumes' visibility, compare the stacks with other sinter plant stacks worldwide, and suggest countermeasures to completely stop the visibility of emissions. The appearance of the sinter plant stack emission changes with time and the background color of the sky due to the scattering effect of the sunlight and incidence angle. The flue gas samples were collected at the outlet of the emission control equipment and observed under optical and scanning electron microscopes. The characterization was performed with the help of an electron dispersive spectroscope and mapping technique. The contents of the stack of a sinter plant without a bag filter had much higher levels of PM10, SO2, and NOx. The emissions from all the sinter plants were invariably found to have particulates of SO2 and NOx of size less than 2.5 microns. It is suggested to opt for state-of-the-art fabric filter technology to eliminate PM2.5 emissions also.

Cluster and multivariate analysis to study the diffuse contamination of emerging per- and polyfluoroalkyl substances (PFAS) in the Veneto Region plain (North-eastern Italy).

In recent years, per- and polyfluoroalkyl substances (PFAS) have emerged as major pollutants of concern. This study considered a real case of superficial and groundwater contamination caused by a set of 15 persistent, carcinogenic, and bioaccumulative compounds. The study area is the Veneto Region floodplain in Italy, where a huge contamination mainly caused by a persistent spill-over from a former chemical factory was discovered in 2013. The contamination path studied in 2013 followed mainly two directions: the first towards east, to the city of Vicenza, and the second following the course of Chiampo and Agno streams, southwards. To identify the major patterns of contamination, a Factor Analysis (PCA) in conjunction with a Cluster Analysis (CA) was performed. The reviewed dataset is composed by PFAS concentration values collected from 2013 to 2021 in groundwater, superficial waters, in natural sources, and in proximity to three industrial discharges, throughout a 3600 km2 area. The CA results were cross-referenced with the water table interpolation, yielding a match between the groundwater flow directions and the observed patterns of the two main plumes. The persistence of pollutants was finally investigated by analyzing distances between the former chemical factory, an industrial wastewater collector which lies along Chiampo and Agno valleys that host residential and industrial areas, and the other sampling points collected in the dataset. The findings confirmed the importance of assessing anthropic background levels of contamination and highlighted the necessity to include the PFAS issue in a national health-based drinking water quality guideline.

Relative sensitivity of hydrodynamic, thermodynamic, and chemical processes for simulating the buoyant multiphase plume and surfacing flows of an oil and gas blowout.

Deepwater hydrocarbon releases experience complex chemical and physical processes. To assess simplifications of these processes on model predictions, we present a sensitivity analysis using simulations for the Deepwater Horizon oil spill. We compare the buoyant multiphase plume metrics (trap height, rise time etc), the hydrocarbon mass flowrates at the near-field plume termination and their mass fractions dissolved in the water column and reaching the water surface. The baseline simulation utilizes a 19-component hydrocarbon model, live-fluid state equations, hydrate dynamics, and heat and mass transfer. Other simulations turn-off each of these processes, with the simplest one using inert oil and methane gas. Plume metrics are the least sensitive to the modeled processes and can be matched by adjusting the release buoyancy flux. The mass flowrate metrics are more sensitive. Both liquid- and gas-phase mass transfer should be modeled for accurate tracking of soluble components (e.g. C1 - C7 hydrocarbons) in the environment.

The Problem with 'Suction Only' Methods to Reduce Surgical Smoke Exposure.

Surgical staff and patients are frequently exposed to surgical smoke and there is mounting evidence that this may be harmful. Borsetti et al. have devised a novel approach to minimising intraoperative exposure to surgical smoke. Here, I briefly outline my concerns with the 'suction only' approach to addressing this problem. LEVEL OF EVIDENCE V: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Assessing the influence of non-uniform gas speed on the melt pool depth in laser powder bed fusion additive manufacturing.

Purpose: This paper aims to investigate the influence of non-uniform gas speed across the build area on the melt pool depth during laser powder bed fusion. The study focuses on whether a non-uniform gas speed is a source of process variation within an individual build. Design/methodology/approach: Parts with many single-track laser scans were printed and characterized in different locations across the build area coupled with corresponding gas speed profile measurements. Cross-sectional melt pool depth, width, and area are compared against build location/gas speed profiles, scan direction, and laser scan speed. Findings: The study shows that the melt pool depth of single-track laser scans produced on parts are highly variable. Despite this, trends were found showing a reduction in melt pool depth for slow laser scan speeds on the build platform near the inlet nozzle and when the laser scans are parallel to the gas flow direction. Originality/value: A unique dataset of single-track laser scan cross-sectional melt pool measurements and gas speed measurements was generated to assess process variation associated with non-uniform gas speed. Additionally, a novel sample design was used to increase the number of single-track tests per part, which is widely applicable to studying process variation across the build area.

Integrated Infrared Radiation Characteristics of Aircraft Skin and the Exhaust Plume.

Infrared radiation (IR) characteristics are important parameters for detecting, identifying, and striking military targets in the context of systematic countermeasures. Accurate calculation of IR characteristics for aircraft is significant for the simulation of war situations and the designation of combat strategy. In this work, integrated IR characteristics of aircraft skin and exhaust plume and their interaction are investigated by considering the reflection based on a bi-directional reflectance distribution function and various influence factors such as solar irradiation, ground reflection, aerodynamic heating, and projection radiation from the background. Combined with infrared emission and reflection characteristics of the skin, omnidirectional IR intensity distributions of 3-5 µm and 8-14 µm at different Mach numbers are obtained. The exhaust plume IR characteristic for different waves and wavebands are also investigated by considering the presence or absence of base and the difference in nozzle inlet temperature. On this basis, integrated IR characteristics between the skin and exhaust plume are investigated. Results show that aircraft IR characteristics of 3-5 µm are concentrated in the exhaust plume and high-temperature skin near the exhaust plume, while the signals of 8-14 µm are concentrated in the skin. The research results are expected to supply guidance for better detection and identification of typical flight targets.

A dry ancient plume mantle from noble gas isotopes.

Primordial volatiles were delivered to terrestrial reservoirs during Earth's accretion, and the mantle plume source is thought to have retained a greater proportion of primordial volatiles compared with the upper mantle. This study shows that mantle He, Ne, and Xe isotopes require that the plume mantle had low concentrations of volatiles like Xe and H2O at the end of accretion compared with the upper mantle. A lower extent of mantle processing alone is not sufficient to explain plume noble gas signatures. Ratios of primordial isotopes are used to determine proportions of solar, chondritic, and regassed atmospheric volatiles in the plume mantle and upper mantle. The regassed Ne flux exceeds the regassed Xe flux but has a small impact on the mantle Ne budget. Pairing primordial isotopes with radiogenic systems gives an absolute concentration of 130Xe in the plume source of ∼1.5 × 107 atoms 130Xe/g at the end of accretion, ∼4 times less than that determined for the ancient upper mantle. A record of limited accretion of volatile-rich solids thus survives in the He-Ne-Xe signatures of mantle rocks today. A primordial viscosity contrast originating from a factor of ∼4 to ∼250 times lower H2O concentration in the plume mantle compared with the upper mantle may explain (a) why giant impacts that triggered whole mantle magma oceans did not homogenize the growing planet, (b) why the plume mantle has experienced less processing by partial melting over Earth's history, and (c) how early-formed isotopic heterogeneities may have survived ∼4.5 Gy of solid-state mantle convection.

Direct Measuring Particulate Matters in Smoke Plumes from Chimneys in a Textile Dyeing Industrial Park by a Self-Developed PM Detector on an UAV in Yangtze River Delta of China.

Directly measuring particulate matters (PM) from chimneys in an industrial park is difficult due to it being hard to reach the peak heights. A self-developed PM detector on an unmanned aerial vehicle (UAV) had been deployed to directly measure the PM emissions in smoke plumes from chimneys in a textile dyeing industrial park. Compared with a commercial PM device (LD-5R, SIBATA, Kyoto, Japan), the self-developed detector showed similar performance with a good correlation (R2 varying from 0.911 to 0.951) in simultaneously vertical PM measurements on UAV. The PM emissions from chimneys after different textile treating processes, including pigment printing, dyeing process, and digital printing, were investigated. PM mass concentrations and particle number concentrations (PNC) in different sizes were found to be significantly higher in pigment printing than those in dyeing process and digital printing by 2 or 3 times after electrostatic precipitation. The activated carbon adsorption and electrostatic precipitation were the major PM controlling techniques in the park. The PM mass concentrations and PNC were the highest in the process of dyeing after activated carbon adsorption with the concentrations of PM1 (1000 µg·m-3), PM2.5 (1600 µg·m-3), and PM10 (2000 µg·m-3), respectively. According to the results of PM and PNC, PM2.5 was found to be the dominant particles accounting for 99% of the PM emissions. It may be due to the high temperature in thermo-fixing machine, which is beneficial to the PM2.5 generation. This study revealed PM2.5 was the dominant particles to be reduced in textile dyeing enterprises to mitigate PM pollution.

Robotic-assisted Total Hysterectomy with Low Pneumoperitoneal Pressure (6 mmHg) and Use of Surgical Plume Evacuator System to Minimize Potential Airborne Particles According to the Joint Statement on Minimally Invasive Gynecologic Surgery during the COVID-19 Pandemic: A Case Report from Japan.

We presented a case of uncontrolled genital bleeding caused by subserosal fibroid and treated by robotic-assisted hysterectomy during the coronavirus disease 2019 (COVID-19) pandemic. A 49-year-old woman had severe anemia with hypermenorrhea due to submucosal fibroid. Hysterectomy was deemed necessary to control genital bleeding. However, at that time, the number of confirmed COVID-19 cases has been increasing in Japan. Serious concerns have been raised about the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) dissemination during minimally invasive surgery due to pneumoperitoneum-associated aerosolization of particles. We tried to prevent the spread of surgical plume by performing surgery under low pneumoperitoneal pressure at 6 mmHg and by using an evacuation/filtration system. As a result, we successfully performed robotic-assisted hysterectomy with minimized risk of spreading surgical plume-containing aerosol particles into the operating room. It is essential to follow the guidelines issued by the relevant societies and act accordingly to reduce the risk of SARS-CoV-2 infection in medical settings while performing surgery. We hope that our experience will help prevent secondary cases of future SARS-CoV-2 infections.