Vent Flow Research Articles

Mechanical Measurement Approach to Characterize Venting Behavior during Thermal Runaway of 18650 Format Lithium-Ion Batteries

The propagation of thermal runaway in a battery system is safety-critical in almost every application, such as electric vehicles or home storage. Abuse models can help to undestand propagation mechanisms and assist in designing safe battery systems, but need to be well-parametrized. Most of the heat during thermal runaway is released by venting that is why the characteristic of the vent flow plays an important part in the safety assessment. During venting, the cell generates a recoil force like a rocket, which depends on the flow speed and flow rate of the gas. This principle is used in this work to measure the velocity and mass flow rate of the vent gas. High-power and high-energy 18650 format lithium-ion batteries were overheated and the recoil and weight forces were measured to determine the venting parameter during thermal runaway. Our results show, that the linearized gas flow rate for the high-power and high-energy cell is 22.15gs−1 and 27.92gs−1, respectively. The progress of the gas velocity differs between the two cell types and in case of the high-energy cell, it follows a single peak asymmetrical pattern with a peak of 398.5ms−1, while the high-power cell shows a bumpy pattern with a maximum gas velocity of 260.9ms−1. The developed test bench and gained results can contribute insights in the venting behavior, characterize venting, support safety assessments, simulations and pack design studies.

Numerical investigation on upper layer thickness and temperature rise in a fire in two rooms connected through a side vent

Upper layer thickness and temperature rise in a fire in two rooms connected through a side vent were numerically investigated. Side vents of SV-1 and SV-2 were installed between two rooms (R-1 and R-2) and between R-2 and the outside, respectively. Situations in which fires occurred in R-1 and R-2, referred to as R-1-F and R-2-F, respectively, were tested. Effects of heat release rate (HRR), SV-1 width (W1), SV-2 width (W2), and room boundary wall material (hk) on the upper layer thickness and temperature rise in the fire and adjacent rooms were examined using the velocity profile and mass flow rate of vent flow. W1 and W2 had the greatest impact on the upper layer thickness in R-1 of R-1-F and in the other rooms, respectively, whereas the effect of hk was the smallest. HRR and hk had the greatest and smallest impacts, respectively, on the upper layer temperature rise. Bias factors and model's relative standard deviations of upper layer thickness, upper layer temperature rise, and vent flow velocity were evaluated. Based on the numerical simulation data and bias factor, correlations for predicting the upper layer temperature rises in the fire and adjacent rooms of R-1-F and R-2-F were proposed.

Validation of a New Method for Continuous Flare Combustion Efficiency Monitoring

A new method is described for calculating flare combustion efficiency (CE) and destruction and removal efficiency (DRE) using a numerical parametric model. The method combines key variables that affect flare performance including the flare vent gas net heating value (NHV), flare design, flow rate, exit velocity, and inert gas composition, alongside the environmental influence of crosswind speed. Each effect is characterized using a parametric model derived from experimental testing data and computational fluid dynamics (CFD). The inclusion of CFD allows the model to be extended into the high-wind conditions that cannot be adequately controlled for in empirical testing yet represent some of the most challenging conditions in which to maintain good combustion. This new parametric model method (PMM) is coupled with ultrasonic flowmeters from which the molecular weight and net heating value of the flare gas can be derived using the vent gas speed of sound measurement. In doing so, this method provides a reliable continuous flare combustion efficiency measure that can be deployed at scale with minimum hardware updates. The system was verified using an extractive sampling method with tests conducted on three full-scale industrial flares including non-assisted, single-arm pressure-assisted, and multi-arm pressure-assisted flare designs. A total of seventy valid test points were carried out with varying flow rate and flare gas heating value, covering a CE range from 46–100%. The uncertainty of the method was assessed using both traditional error propagation and Monte Carlo methodology. The results from the new method agree with the extractive method to within 0.8% in the ≥98% DRE region where flares are expected to operate to limit the impacts of flaring as a source of methane as a greenhouse gas. Uncertainty analysis revealed that the larger DRE discrepancy for DRE ≤ 98% correlates to the measurement uncertainties for both methods.

Effect of Compartment Height with Fire Source on Horizontal Vent Flow and Temperature Distribution

The effect of compartment height with a fire source on the horizontal vent flow and temperature distribution was numerically investigated. Two compartment heights were examined, namely 1.1 m (H1.1) and 5.5 m (H5.5). Horizontal vent areas were set at 1% (HV01) and 10% (HV10) of the floor area, and fire sources were positioned at the center (FSC) and side (FSS). H1.1 exhibited a larger mass flow rate and higher velocity of vent flow than H5.5 for FSC cases with HV01 and HV10. In the case of HV01 with FSS, the mass flow rates between H1.1 and H5.5 were comparable. However, in the case o f HV10 w ith F SS, H5.5 d emonstrated a larger m ass flow r ate than H 1.1. V ent flow v elocities a ppeared similar between H1.1 and H5.5 for FSS cases with both HV01 and HV10. Meanwhile, H1.1 exhibited a higher temperature distribution than H5.5 for HV01 cases with FSC and FSS. For HV10 with FSC, H5.5 showed a higher temperature distribution than H1.1. Conversely, for HV10 with FSS, the opposite trend was observed. The previous correlation overestimated the results of the present numerical simulation regarding the fire plume centerline temperature rise. It was speculated that mixing within the compartment affected the trend of fire plume centerline temperature rise.

Experimental investigation of the dynamic evolution of cavity during the free water-exit of a high-pressure venting vehicle

The underwater vehicle is subjected to complex hydrodynamic loads during water-exit process, which seriously affect the structural strength and water-exit stability of the vehicle. This paper investigates the effect of high-pressure venting conditions on the dynamic evolution characteristics of the cavity during the completely free water-exit of a vehicle based on self-designed experiments. Some novel phenomena are found in the experiment, and the hypothesis of constant acceleration is established to explain the formation mechanism. The results reveal that the reentrant jet is the main factor influencing the pattern of cavity development and causes great differences between the partial and supercavity states. The balance between the initial cavity volume increase and the gas leakage rate results in the fact that increasing the launch Froude number in the partial cavity state does not cause significant changes in the cavity size. There is a stable interval between 0.0038 and 0.03 for the effect of gas entrainment coefficient on the development of the cavity. The influence of the launch Froude number on the cavity morphology varies within different gas entrainment coefficient ranges. Besides, six patterns of cavity closure are found for free water-exit conditions. The coupling closure pattern of reentrant jet and interaction vortex tube is the most stable during the water-exit process. The stable development intervals of cavity closure pattern and cavity morphology are roughly the same. The present study aims to provide a reference for the active venting flow control of the vehicle during water-exit.

Successful treatment of cardiogenic shock due to Takotsubo syndrome with implantation of a temporary microaxial left ventricular assist device in transaxillary approach

ObjectivesCardiogenic shock (CS) can occur in patients with Takotsubo syndrome (TTS). As TTS has received increasing attention and has been more closely researched, several aspects of the pathogenesis have been identified, particularly that an excessive release of catecholamines plays an important role. Nevertheless, evidence on specific therapy concepts is still lacking. As a result, TTS with severe hemodynamic instability and low cardiac output creates unique challenges, and mechanical circulatory support is needed with as few inotropic drugs as possible.MethodsWe present a 77-year-old female patient who underwent minimally invasive surgical mitral valve replacement. After an uneventful course, the patient developed acute heart failure eleven days after surgery. Transthoracic echocardiography (TTE) revealed a new onset of TTS. The patient needed left ventricular venting and full haemodynamic flow. We successfully implanted a microaxial left ventricular assist device (Impella 5.5) using the transaxillary approach. The haemodynamic situation stabilised immediately. The patient was weaned and the Impella 5.5 was explanted after five days.ConclusionWe present the first-in-man implantation of a transaxillary Impella 5.5 in a patient with TTS. The patient benefitted from Impella 5.5 therapy with full haemodynamic support and venting of the left ventricle.

Comparative Study of Numerical Simulation and Experiment on Temperature Distribution and Central Vent Flow Velocity in Ceiling-vented Compartment Fire

In this study, we conducted numerical simulations to analyze fire phenomena in a compartment with a ceiling vent and compared these numerical simulation results with previous experimental data. Based on the previous experimental conditions, under the heat release rate of 1.5 kW, the vent areas of 1% and 10% of the floor area and the fire sources both at the center and side of the floor were tested. Overall trends of temperature distribution and central vent flow velocity in the present numerical simulations were consistent with those in the previous experiments. The temperature within the compartment was observed to be higher when the vent area was smaller. For compartment with a smaller vent area, the temperature distribution showed minor variations with the fire source location. However, with a larger vent area, temperatures were notably higher when the fire source was at the side than at the center. The present numerical simulations slightly overestimated the temperatures from the previous experimental results, resulting in a bias factor of 1.07 and a model's relative standard deviation of 0.07 for temperature. Regarding the flow velocity at the center of ceiling vent, the fluctuations over time were more pronounced when the fire source was centrally located. When the fire source was at the center, the average central vent outflow velocity was higher for compartment with a larger vent area. When the fire source was positioned to the side, the vent area appeared to have minimal impact on the average central vent outflow velocity. It was also observed that the average central vent outflow velocity was higher when the fire source was centrally placed when compared to a side location. The present numerical simulations underestimated the previous experimental results for the average central vent outflow velocity, and the bias factor and the model’s relative standard deviation for the average central vent outflow velocity were 0.63 and 0.39, respectively.

Effects of Fire Source Conditions on Vent Flow Velocity and Hot Gas Layer Characteristics in Two Rooms Connected by Vertical Opening

In this study, the effects of fire source conditions on the vent flow velocity and hot gas layer characteristics in two rooms (ROOM-I and ROOM-II) connected by a vertical opening (VO-I) were investigated experimentally. In ROOM-II, the vertical opening (VO-II) connected to the outside was installed. The fire sources were located at the centers of ROOM-I and ROOM-II, and the heat release rates were 1.32, 3.32, and 5.21 kW. Regarding the vent flow velocity, when the fire source was located in ROOM-I, the outflow of the hot gas and inflow of cold air occurred in the upper and lower parts of VO-I and VO-II, respectively, which were the same as those of VO-II when the fire source was located in ROOM-II. However, when the fire source was located in ROOM-II, the hot gas in the upper part of VO-I flowed out to ROOM-I and flowed again into ROOM-II. Additionally, the hot gas layer thickness and temperature rise in the fire and adjacent rooms were compared. In the fire room, the case where the fire source was placed in ROOM-I showed a thicker hot gas layer and a higher hot gas layer temperature rise than the case where the fire source was placed in ROOM-II. In the adjacent room, the case where the fire source was placed in ROOM-I showed a thinner hot gas layer and a higher hot gas layer temperature rise than the case where the fire source was placed in ROOM-II. The dependence of the hot gas layer temperature rise on the heat release rate was higher than that of the hot gas layer thickness.

Experimental investigation on effect of fire source location on compartment fire phenomena with a single natural ceiling vent

ABSTRACT The effect of fire source location (FSL) on compartment fire phenomena with a single natural ceiling vent was experimentally investigated under various vent area (VA) and heat release rate (HRR) conditions. Two FSL cases, where the fire source was located at the centre (FSLC) and on the side (FSLS) of the floor, were tested. In the bidirectional vent flow patterns of FSLC and FSLS, the detailed locations where the smoke outflow and the fresh air inflow occurred were different. Empirical correlations were proposed for predicting the smoke outflow areas. FSLC exhibited a higher central velocity of the outflow, larger estimated mass flow rate of the outflow, and lower temperatures inside the compartment than FSLS. The estimated mass flow rate of the outflow depended more on VA than on HRR. A previous correlation was more suitable for FSLS than FSLC in predicting the mass flow rate of the outflow.

Shock wave dynamics and venting overpressure hazards induced by indoor premixed hydrogen/air explosion

To further investigate the venting shock wave dynamics and overpressure hazards induced by indoor hydrogen/air explosion, an explosion-venting model of 6 m × 3 m × 2.5 m with a vent was established by computational fluid dynamics (CFD) technology. The results show that the combustion rate structure of venting flame composed of three peaks completely reflects the evolution of the venting flow field, and the significance and arrival time of the peak R3 reflect the severity and hysteresis of the external explosion; The propagation of the external explosion wave in two directions, away from and near the vent, resulting in the evolution of the traditional two-wave and three-area structure into a three-wave and four-area structure. The new wave structure contains the reverse cancellation of the external explosion wave and explosion-venting wave, and the co-direction superposition with the precursor wave, in which the wave-wave superposition forms a new significant peak Ps-max; The distribution characteristics of venting overpressure hazard under the external explosion and wave-wave superposition become unpredictable. The severe damage zone to building will evolve repeatedly on the explosion-venting path, and the dead zone may appear far away from the vent. The research results provide a scientific basis for the prevention and mitigation of explosion disasters in hydrogen-related industrial plants.

Effect of Vent Area Ratio on Vent Flow Characteristics and Temperature D istribution in a C ompartment F ire with T wo Ceiling Vents

In this study, the effect of the vent area ratio on vent flow characteristics and temperature distribution in a compartment during a fire in the compartment with two ceiling vents was examined. The area ratio (A<sub>1</sub>/A<sub>2</sub>) between ceiling vent 1 (CV1), with a duct height of 0.19 m, and ceiling vent 2 (CV2), with a duct height of 0.05 m, was varied from 0.052 to 0.542, 1, 5.587, and 19.36, and numerical simulation was performed under these conditions. As the A<sub>1</sub>/A<sub>2</sub> ratio increased, the flow pattern changed from unidirectional inflow to bidirectional flow for CV1 and from bidirectional flow to unidirectional inflow for CV2. When the A<sub>1</sub>/A<sub>2</sub> ratio was 0.542, the outflow and inflow mass flow rates for CV1 and CV2 were found to be nearly equal. The outflow and inflow mass flow rates at CV1 were higher than those at CV2 when the A<sub>1</sub>/A<sub>2</sub> ratio was high, while the outflow and inflow mass flow rates at CV2 were higher than those at CV1 when the A<sub>1</sub>/A<sub>2</sub> ratio was low. Furthermore, it was observed that the temperature was lower and the temperature difference between the higher and lower regions in the upper part of the measurement position decreased near the lower part of the vent with a larger area compared to the vent with a smaller area. This was probably because the mixing effect increased near the vent with a larger area due to the occurrence of the active bidirectional flow pattern. When the flow pattern at CV1 was bidirectional, the previous correlation for predicting mass flow rate was examined. It was found that the previous correlation underestimated the mass flow rate of the numerical simulation conducted in this study.

Effects of Duct Height and Fire Location on Fire Phenomena of Enclosure with Two Horizontal Vents Installed on Ceiling

The effects of duct height (DH) and fire location (FL) in an enclosure on the mass flow rate and flow pattern of horizontal vent (HV) flow and temperature distribution in the enclosure were investigated through numerical simulations under the condition that two HVs were installed on the ceiling of the enclosure. To evaluate the effect of DH, DHs of HV1 were set to 0.19 m (HV1_DH0.19) and 0.05 m (HV1_DH0.05) under the condition that DH of HV2 was 0.05 m (HV2_DH0.05). The effect of FL was evaluated in three cases where the fire sources were located in the center of the floor (F LC), below HV1 (F L1), and below HV2 (F L2). With respect to the DH effect, the total mass flow rate of the vent flow was slightly higher and temperature was slightly lower in the case of HV1_DH0.19 than that in the case of HV1_DH0.05. However, considering the error bars, the effect of DH in this numerical simulation condition was considered to be insignificant. Furthermore, bidirectional flow patterns appeared in HV1 and HV2 in both DH conditions. Meanwhile, with respect to the FL effect, a bidirectional flow dominated by the mass flow rate of outflow occurred in the HV where the fire source was located, and a unidirectional inflow dominated by the mass flow rate of inflow occurred in the HV where the fire source was not located. The total mass flow rates of FL1 and FL2 conditions were similar, which were higher than those of FLC condition. The temperature was higher in FLC than those in FL1 and FL2. This was due to the small mass flow rate through the HV in the FLC. Meanwhile, an increasing trend of the temperature with the rising measurement height from the floor was observed at most of the temperature measurement points. However, when the fire source was located below HV1 and HV2, as the height from the floor increased, the temperature decreased and the overall temperature was low at the temperature measurement points below the vent where the fire source was not located. This trend was attributed to the occurrence of a strong unidirectional inflow wherein a large volume of low-temperature air flowed into the enclosure from the HV where the fire source was not located.

Influence of vent size and vent burst pressure on vented ethylene-air explosion: Experimental and numerical study

This paper describes the numerical simulation of the vented explosion of ethylene-air mixtures. The influence of concentration, vent size, and vent burst pressure on the vented ethylene-air explosion is investigated by comparing simulation results and experiments. The different phases of external flame propagation are concluded by comparing the experimental photos and the simulation results. The external explosion process is captured by the high-speed camera and simulation. It is found that the unburned mixture expanded to the external atmosphere, which was ignited by the flame. The flow velocity, velocity vector, and turbulence kinetic energy are applied to analyze the mechanism of external flame propagation. The velocity vector is deflected to both sides of the flame front and the reverse flow velocity is captured in the external flow field. The change of ethylene concentration and the venting flow velocity is used to explain the relationship between the pressure rise, chemical reaction rate, and venting flow. Results show that the internal pressure for AV= 0.18 m2 is significantly greater than the internal pressure for AV= 0.55 m2 in this case. The smaller vent size results in higher flow velocity and turbulence kinetic energy inside of the vessel. The vent burst pressure growth promotes the acceleration of the flame front inside of the vessel. The variation curve of ethylene concentration and venting flow velocity has a similar law with different vent burst pressures. The experimental and simulated results can provide technical and theoretical support for the design of gas explosion prevention in the field of process safety and risk engineering.

Stochastic modelling of wellbore leakage in British Columbia

Wellbore leakage is complicated to understand due to the range of potential leakage pathways and uncertainties regarding their capacities. In this study we present a novel approach to modelling realistic leakage along microannulus pathways of varying thickness. We use stochastic methods to calibrate leakage pathway dimensions to the surface casing vent flow (SCVF) leakage rates reported in British Columbia, Canada. Results shows that representing dry microannulus thicknesses with a lognormal distribution provides a good fit for the intermediate ranges of SVCF flow rates, but that a dry microannulus alone cannot account for all instances of wellbore leakage. We then approach small and high flow rates independently, offering explanations for these. This includes a wet microannulus/mud channel model to account for instances of poor mud removal, which is better able to account for the less frequent higher leakage rates. We conclude that flow rates above 10 m3/day are progressively likely to be caused by significant failures in mud displacement during primary cementing, or other extreme events such as casing failure due to geological or operational factors.

Feasibility study and 3E analysis of blowdown heat recovery in a combined cycle power plant for utilization in Organic Rankine Cycle and greenhouse heating

Greenhouse heating plays a key role in the growth and yield of greenhouse crops in cold regions. Moreover, heat loss and energy wastage are abundant in the industry. Therefore, these two subjects are combined in this study to analyze the feasibility of using the steam vent and waste drain flow of a blowdown tank in a combined cycle power plant (CCPP) to provide the required additional heating in a greenhouse by installing a radiant floor heating (RFH) system. For this purpose, a tunnel greenhouse with an east-west orientation is modeled in steady states. In addition, a CCPP integrated with the Organic Rankine Cycle (ORC) is modeled on the energy, exergy, and economic (3E) analysis to comprehensively evaluate the system. The effect of greenhouse heating was analyzed in three months of the year with highest heating demand. According to the results of analyzing four scenarios, the RFH system managed to increase the greenhouse temperature up to 7.5 °C. The results indicated an increase in energy efficiency and exergy efficiency of the system by 0.04% and 0.05%, respectively. Based on the economic analysis, the payback period in the proposed scenario was determined 4.81 years.

Left ventricular venting in veno-arterial extracorporeal membrane oxygenation: A computer simulation study.

Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is the fastest way to restore circulation in refractory cardiogenic shock, however it cannot unload the failing left ventricle. There is a lack of consensus regarding optimal approach to left ventricular venting in V-A ECMO patients with severely depressed or absent left ventricular function. A computer model was developed in Matlab Simulink R20016b (MathWorks, Inc., Natick, MA, USA) to analyze different venting options as well as atrial septostomy in the setting of cardiogenic shock and V-A ECMO. The model has shown an inverse linear relationship between left atrial pressure and either vent, Impella or atrial septum defect flow rate. The minimum vent flow required to prevent pulmonary edema in complete loss of left ventricular function needed to be higher than the bronchial blood flow. Atrial septostomy restored normal pulmonary blood flow with low left atrial pressure but induced stasis in the left ventricle. Venting the pulmonary artery induced stasis in the entire pulmonary circulation as well as left atrium and left ventricle. Venting the left ventricle directly with a cannula or Impella device avoided blood stasis. Our data suggest that reduction of left atrial pressure is linearly related to the vent, Impella or atrial septal defect flow rate. The preferred vent location is the left ventricle as it avoids stasis in the pulmonary circulation and cardiac chambers.

Direct thermal desorption-gas chromatography-tandem mass spectrometry versus microwave assisted extraction and GC-MS for the simultaneous analysis of polyaromatic hydrocarbons (PAHs, PCBs) from sediments

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) are regulated contaminants usually investigated in sediments. Conventional approaches often use GC-MS to analyse them with a preliminary extraction step which can be solvent- and time-consuming. Here two extraction methodologies were optimized using experimental designs, and compared: microwave assisted extraction (MAE) and thermal desorption (TD); the latter was rarely used for sediments analyses. Several factors that may influence extraction recoveries were studied including matrix parameters (mass, organic matter (OM) content) and processing parameters. A definitive screening design DSD was performed to screen the 6 most influencing factors and model the extraction recoveries using TD. Whatever the OM content, a minimum sediment mass (5 mg) was better for an optimal extraction, with a minimum temperature rate (15 °C min−1), a maximum final temperature (350 °C) associated with a minimum hold time (5 min), and a maximum vent flow (150 mL min−1) between the TD unit and the cryogenic trap. Thereafter matrix effects were evaluated using standard addition, and quality assurance and control were implemented for comparing MAE and TD. TD-GC-MS/MS sensitivity was higher than MAE-GC-MS with detection limits in the range 5–1160 pg and 20–125 pg for PAHs and PCBs, respectively. When considering the appropriate strategy for quantification, TD was also reliable for sediments analysis. Although MAE was less sensitive to matrix effects, TD could significantly improve the analytical process, due to direct coupling with GC-MS/MS and complete automation. Moreover, TD offered possible higher spatial resolution than MAE, particularly for sediment cores analysis, due to the 1000-times lower sample size. At last, TD-GC-MS/MS appeared as a greener analytical procedure.

Non-invasive internal pressure measurement of 18650 format lithium ion batteries during thermal runaway

The dynamics of 18650 format lithium ion battery pressure build-up during thermal runaway is investigated to inform understanding of the subsequent pressure-driven venting flow. Battery case strain and temperature were measured on cells under thermal abuse which was used to calculate internal pressure via hoop and longitudinal stress relations. Strain measurement is a non-invasive approach with no impact on the chemical decomposition within batteries that leads to thermal runaway. The experimental methodology and test apparatus were developed and validated through predictable, representative test specimens of open cases and pressurized gas cylinders. Live battery experiments reliably captured the final pressure rise before venting onset. The pressure build up was observed to coincide with the beginning of thermal runaway.

Numerical Simulation on Effects of Horizontal Natural Opening Area and Heat Release Rate on Temperature Distribution and Vent Flow in Small Compartment

In this study, the numerical simulation to investigate the effects of horizontal natural opening areas and heat release rates on temperature distribution and vent flow in a small compartment was performed using a fire dynamics simulator. The reduced scale model of a stage in a real scale theater with horizontal natural opening was selected for this study. The horizontal opening areas were 0.0196, 0.1024, and 0.2025 m<sup>2</sup> (1, 5, and 10% of the floor area, respectively), and the heat release rates were 0.46, 1.35, and 2.61 kW. By decreasing the horizontal opening area and increasing the heat release rate, the temperature in the compartment increased. Additionally, by increasing the heat release rate, the average velocity near the center of the opening increased. For the increase in the horizontal opening area from 0.0196 to 0.1024 m<sup>2</sup>, the velocity near the center of the opening increased. However, when the horizontal opening area increased from 0.1024 to 0.2025 m<sup>2</sup>, the variation in velocity was not noticeable. Considering the analyses of temperature and velocity distributions of vent flow, the bidirectional flow pattern was observed, where the outflow and inflow occurred at the center and edge of the horizontal opening, respectively. The mass flow rate through the horizontal opening increased with the increase in the horizontal opening area and heat release rate. The previous correlation for mass flow rate under-predicted the present numerical simulation data.

Organic Biogeochemistry in West Mata, NE Lau Hydrothermal Vent Fields

AbstractThe impact of submarine hydrothermal systems on organic carbon in the ocean—one of the largest fixed carbon reservoirs on Earth—could be profound. Yet, different vent sites show diverse fluid chemical compositions and the subsequent biological responses. Observations from various vent sites are to evaluate hydrothermal systems' impact on the ocean carbon cycle. A response cruise in May 2009 to an on‐going submarine eruption at West Mata Volcano, northeast Lau Basin, provided an opportunity to quantify the organic matter production in a back‐arc spreading hydrothermal system. Hydrothermal vent fluids contained elevated dissolved organic carbon, particulate organic carbon (POC), and particulate nitrogen (PN) relative to background seawater. The δ13C‐POC values for suspended particles in the diffuse vent fluids (−15.5‰ and −12.3‰) are distinct from those in background seawater (−23 ± 1‰), indicative of unique carbon synthesis pathways of the vent microbes from the seawater counterparts. The first dissolved organic nitrogen concentrations reported for diffuse vents were similar to or higher than those for background seawater. Enhanced nitrogen fixation and denitrification removed 37%–89% of the total dissolved nitrogen in the recharging background seawater in the hydrothermal vent flow paths. The hydrothermal plume samples were enriched in POC and PN, indicating enhanced biological production. The total “dark” organic carbon production within the plume matches the thermodynamic prediction based on available reducing chemical substances supplied to the plume. This research combines the measured organic carbon contents with thermodynamic modeled results and demonstrates the importance of hydrothermal activities on the water column carbon production in the deep ocean.