Fire Site Research Articles

Natural Disaster Risk Assessments for Pine Honey Apiaries in Muğla, Turkey

Since Muğla province has 90% of the world's total pine honey production, ensuring efficiency and economic income requires the determination of measures for apiary locations and estimation of risks. However, ensuring development and productivity requires identifying natural disasters susceptibility such as forest fires and floods to maintain productivity. Muğla province has a high forest fire potential due to its dense forest cover and approximately 200 forest fires occur each year. Forest fires are one of the main factors that threaten apiaries, as there are a lot of apiary places (approximately 15,000) in forests for pine honey. On the other hand, due to the mountainous topography and high precipitation rate of Muğla, the province has a high rate of flood formation (20 per year), which threatens the hive sites by destroying the entire colony. In this study, Apiary Locations Risk Index (ALRI) was carried out to guide the insurance process for apiary locations by applying the Forest Fire Risk Index (FFRI) and the Flood Hazard Risk Index (FHRI). Determination of forest fire risk zones and flood hazard maps requires environmental, forestry, topographic, economic and meteorological parameters to be handled within a decision support platform. For this purpose, Analytical Hierarchy Process (AHP) technique supported by Geographic Information System (GIS) was used in the creation of sensitivity maps. As a result, 1533.40 ha (11.82%) of the study area was determined as extremely risky areas for apiary areas. The results were confirmed with 1454 forest fire sites and 20 flood hazard sites where the Eşen, Dalaman, Çine, Sarıçay, Akçay, Kamiişdere and Namnam rivers were stated to be highly susceptible to flood hazard.

Electrical fire risk assessment of high‐rise buildings based on hybrid decision model considering asymmetric proximity

AbstractAt present, there are some problems in the research of electrical fire risk assessment of high‐rise buildings, such as the evaluation index is relatively single and the fuzziness of evaluation state boundary is not considered. This study proposed an electrical fire risk assessment method of high‐rise buildings based on hybrid decision model considering asymmetric proximity. Based on the occurrence mechanism of electrical fire in high‐rise buildings, a four‐level evaluation index system considering disaster causing body, fire site environment, affected body and fire driving factors is established based on FP growth (Frequent Pattern Tree Growth) mining association rules, and the risk grade is divided further. An improved index weight assignment method for balancing the interaction relationship between indexes is proposed, and a hybrid decision‐making model for electrical fire risk assessment of high‐rise buildings is established. Combined with specific examples, the effectiveness of the proposed building electrical fire risk assessment method is verified. The weight standard deviation of the proposed method is 0.0464, which is about 13.8% smaller than that of analytic hierarchy process (0.0528). So the method can better balance each risk evaluation index, fully consider the fuzziness and randomness in the electrical fire risk assessment of high‐rise buildings, and improve the accuracy and applicability of electrical fire risk assessment.

Zonal features of bioecological properties and honey productivity of species of the family Onagraceae Juss

Representatives of the cypress family (Onagraceae) are among the most valuable melliferous plants of the herbaceous flora of temperate latitudes in Russia. These honeybees are inferior to linden and white acacia among woody plants. It is known that maximum honey yields from the narrow-leaved willow (Epilobium angustifolium L.) are obtained in fresh heaths (3-5 years). The paper considers the dynamics of nectar production in different geographical zones depending on the bioecological characteristics of the honeybee. The ecological conditions on the unforested lands of the Middle Taiga in the Northwest region (Leningrad region) differ significantly from those of the rangelands. Distinct from particularly young havens, which form during certain periods of plant community development. Therefore, the willow herb on forest edges and glades is not as abundant (20 pcs./m2). The number of flowers per plant is lower (62 pcs.) than that of plants on fire sites (92 pcs.). The honey productivity is 140 kg/ha on fallow land and 50 kg / ha at the forest edges. In the taiga zone of western Siberia after deforestation and fires, narrow-leafed willow (Epilobium angustifolium) produces abundant nectar for the first 5-7 years. Control hive readings reach 18-24 kg per day, honey production reaches 350 kg/ha. Analysis of the main pollinators and honey collectors on Cypress flowers showed that in the southern regions of Western Siberia, beekeepers do not feel the presence of competing honeybees. A census of melliferous species in the Vasyugany region revealed the presence of marsh bunting (Epilobium palustre L.), from which bees collect pollen (21.31 g, 2.09 % of total pollen) in July in a beige-purple color. In the south, the honey productivity of the strong bearer cypress (Epilobium angustifolium L.) reaches 800 kg/ha, while in the north it does not produce nectar. On the territory of the Republic of Mari El, the productivity of honey in the burned areas of pine and linden spruce forests, where powerful thickets of willow herb develop, reaches 492 kg/ha.

목재용 오일 마감재(오일스테인) 자연발화 위험성에 관한 연구

Recently, as natural interiors have been in the spotlight, there is a trend to produce and assemble interior accessories using wood or bark. For small items made in this way, an oil finishing material for wood must be used, and the most used currently is oil stain. Linseed oil, which is classified as a drying oil among vegetable oils, is used as the main ingredient in oil stain. Linseed oil, which is a drying oil, consists of unsaturated fatty acids, and many of them are composed of polyunsaturated fatty acids, so it oxidizes very quickly in the air. Because of these properties, there is a risk of spontaneous ignition due to oxidative heat in the process of improperly processing the painting tools generated after wood painting. Therefore, this study analyzes fire cases that occurred at the fire site, and based on this, deduces the possibility of spontaneous ignition due to oxidative heat in painting tools with oil stains through a re-enactment experiment, and suggests considerations for fire detection and fire prevention measures.

Wildfire decouples soil multi-element cycles: Contributions of legacy effects and temporal variations

High-severity wildfires may lead to significant impacts on biogeochemical cycling both by burning biomass and by fire legacies. However, the legacy effects of wildfires on multiple soil element cycles across temporal trajectories have rarely been discussed. Here, we evaluated the availability and stability of seven essential soil elements and their stoichiometric ratios, as well as the coupling of multiple and individual elements, over more than two years in a half-mature, severely burnt (SB) artificial Pinus tabuliformis Carr. forest in North China (Beijing) in comparison with the unburnt (UB) control. Despite element concentrations jumped up and down remarkably during the first few months, results showed that the average availability and stability of all elements in soils of the SB site were lower than those of the UB site and legacy effects of fire were consistently significant on available nitrogen (N), phosphorus (P) and sodium. Temporal trajectories (months to years) varied amongst elements, and organic carbon (C) and N depleted more than other elements did. High levels (i.e. above the null model threshold) of multi-element coupling in soils of the UB site were maintained during our monitoring periods. By contrast, a reduction in the degree of element coupling was detected over time in soils of the SB site, which was concomitant with the core role of C and the great variability of P. Fire- and time-induced shifts in cation exchange capacity, acid phosphatase activity, capillary porosity and aggregate fraction dominated the uncoupling of multiple soil elements, implying the critical contributions of fire legacy effects and temporal variations. These responses have important implications for the consideration of additional long-term studies because such biogeochemical decoupling of elements may have unpredicted consequences under global change scenarios. Meanwhile, this work is helpful to predict the direction of ecosystem succession and to provide scientific evidence for management practices.

Monitoring the spontaneous combustion zone of a rock-coal massif using the ground-penetrating radar method

Introduction. Endogenous fires are common and one of the most complex types of accidents in the mining industry. The main cause of endogenous fires is oxidation of combustible rock by oxygen. Existing fires significantly complicate mining operations, lead to the loss of coal reserves prepared for excavation, expensive coal-mining equipment, and cause huge economic losses associated with firefighting operations. Fired areas are sources of emissions of gases harmful for breathing into the atmosphere, so the environmental damage is also very significant. Due to the fact that endogenous fires are difficult to predict and forecast, especially in their initial stages, their study is relevant to scientists of the leading research institutes of the mining industry. Research objective is to investigate and analyze the effectiveness of the ground-penetrating radar (GPR) method for diagnosing the spontaneous-combustion zones of the rock-coal massif. Methods of research. In order to assess the effectiveness of the GPR method, field experimental studies on the recognition and localization of underground fires were carried out. In order to determine the informative value of this method, wells were drilled and geological data was compared with the GPR survey results. Results. The site of an active underground fire was visually inspected to predefine the combustion areas; inspection results were presented in the paper. Using the method of GPR sounding and based on the typical anomalous zones location on fire radiograms, the fire sources were diagnosed by depth and on the plan. Boreholes were drilled to study the lithological structure of the rock mass. Additional GPR sounding was aimed at defining the width of the fire in plan more precisely. Conclusions. The GPR method makes it possible to obtain on-line data on the location of coal massif spontaneous-combustion zones and their sizes. This technology contributes to timely measures for preventing the development of underground fires in the territories of mines and open pits surface plants.

A Wilderness of Smoke and Mirrors: Exploring Interstitial Spaces in the Anthropocene

Monument 83/Holdover Peak is located along the international border of Canada and the United States. Situated in a subalpine clearing of E.C. Manning Park in southwestern British Columbia, this area is part of the shared traditional territories the Stó:lōand Similkameen First Nations. It was traditionally used as a meeting ground for fishing, hunting,and trading, and the present-day Skyline Trail was a well-used travel route. Monument 83 is notable for its location as a fire lookout site. The US Forest Service built a cupola-style log cabin in 1930, but an international border survey during the 1960’s determined that the existing lookout was actually located on the Canadian side of the border, so it became the southernmost fire outlook in Canada(Redwic, n.d.). Today two fire towers exist, situated in a burnt-outregion: the old lookout ontothe Canadian side and the more recently built fire tower on the American sideof the border, which is still used occasionally. ...

Assessing Ecological Recovery of Reclaimed Well Sites: A Case Study From Alberta, Canada

Empirical evaluations of reclamation success are critical for understanding the speed of ecosystem recovery and improving best practices. In this study, we provide a quantitative evaluation of the effectiveness of past (pre-1995) and current (2010) reclamation criteria in creating functioning forest ecosystems on former industrial sites in boreal Alberta, Canada. We compared ecological indicators of ecosystem recovery (vegetation structure and soil properties) on mineral surface leases (MSLs) certified to the pre-1995 or 2010 reclamation criteria with nearby reference areas recovering from harvest (CUT) or fire (FIRE) disturbances. Six CUT and FIRE sites were chosen to compare six 1995MSLs and five 2010MSLs. Averaging 8 years since reclamation, most of the 2010MSLs were characterized by many of the same vegetation structure and soil properties as the FIRE and CUT sites. The 1995MSLs tended to support more agronomic species, notably grasses and non-native forbs, and fewer shrubs, trees, and native forbs than CUT or FIRE sites. Sites with the greatest coverage of herbaceous species (native and non-native grasses as well as non-native forbs) were the most ecologically impaired sites, based on the extreme deviation from reference site conditions. Based on these results, 2010 reclamation criteria appear to be more effectively promoting ecosystem recovery on reclaimed industrial sites than the pre-1995 criteria. While this case study illustrated the potential benefits of straightforward changes to reclamation criteria in terms of including metrics around soil quality and conservation, woody stem requirements and native plant coverage, there is ultimately always room for improvement. For jurisdictions where the objective of the criteria is to restore a forest ecosystem, including criteria geared toward tree establishment would likely be of value in ensuring the speedy return to a forest canopy state. Adding criteria with measures of native plant species diversity may also be of utility as it is well understood that having plant diversity is also a beneficial metric in creating a more resilient vegetation community.

Regional impacts of black carbon morphologies on shortwave aerosol–radiation interactions: a comparative study between the US and China

Abstract. Black carbon (BC) is one of the dominant absorbing aerosol species in the atmosphere. It normally has complex fractal-like structures due to the aggregation process during combustion. A wide range of aerosol–radiation interactions (ARIs) of BC have been reported throughout experimental and modeling studies. One reason for the large discrepancies among multiple studies is the application of the oversimplified spherical morphology for BC in ARI estimates. In current climate models, the Mie theory is commonly used to calculate the optical properties of spherical BC aerosols. Here, we employ a regional chemical transport model coupled with a radiative transfer code that utilizes the non-spherical BC optical simulations to re-evaluate the effects of particles' morphologies on BC shortwave ARI, and the wavelength range of 0.3–4.0 µm was considered. Anthropogenic activities and wildfires are two major sources of BC emissions. Therefore, we choose the typical polluted area in eastern China, which is dominated by anthropogenic emissions, and the fire region in the northwest US, which is dominated by fire emissions in this study. A 1-month simulation in eastern China and a 7 d simulation in the fire region in the northwest US were performed. The fractal BC model generally presents a larger clear-sky ARI compared to the spherical BC model. Assuming BC particles are externally mixed with other aerosols, the relative differences in the time-averaged clear-sky ARI between the fractal model with a fractal dimension (Df) of 1.8 and the spherical model are 12.1 %–20.6 % and 10.5 %–14.9 % for typical polluted urban cities in China and fire sites in the northwest US, respectively. Furthermore, the regional-mean clear-sky ARI is also significantly affected by the BC morphology, and relative differences of 17.1 % and 38.7 % between the fractal model with a Df of 1.8 and the spherical model were observed in eastern China and the northwest US, respectively. However, the existence of clouds would weaken the BC morphological effects. The time-averaged all-sky ARI relative differences between the fractal model with a Df of 1.8 and the spherical model are 4.9 %–6.4 % and 9.0 %–11.3 % in typical urban polluted cities and typical fire sites, respectively. Besides, for the regional-mean all-sky ARI, the relative differences between the fractal model and the spherical model are less than 7.3 % and 16.8 % in the polluted urban area in China and the fire region in the US, respectively. The results imply that current climate modeling may significantly underestimate the BC ARI uncertainties as the morphological effects on BC ARI are ignored in most climate models.

Modeling the systemic risks of COVID-19 on the wildland firefighting workforce

Wildfire management in the US relies on a complex nationwide network of shared resources that are allocated based on regional need. While this network bolsters firefighting capacity, it may also provide pathways for transmission of infectious diseases between fire sites. In this manuscript, we review a first attempt at building an epidemiological model adapted to the interconnected fire system, with the aims of supporting prevention and mitigation efforts along with understanding potential impacts to workforce capacity. Specifically, we developed an agent-based model of COVID-19 built on historical wildland fire assignments using detailed dispatch data from 2016–2018, which form a network of firefighters dispersed spatially and temporally across the US. We used this model to simulate SARS-CoV-2 transmission under several intervention scenarios including vaccination and social distancing. We found vaccination and social distancing are effective at reducing transmission at fire incidents. Under a scenario assuming High Compliance with recommended mitigations (including vaccination), infection rates, number of outbreaks, and worker days missed are effectively negligible, suggesting the recommended interventions could successfully mitigate the risk of cascading infections between fires. Under a contrasting Low Compliance scenario, it is possible for cascading outbreaks to emerge leading to relatively high numbers of worker days missed. As the model was built in 2021 before the emergence of the Delta and Omicron variants, the modeled viral parameters and isolation/quarantine policies may have less relevance to 2022, but nevertheless underscore the importance of following basic prevention and mitigation guidance. This work could set the foundation for future modeling efforts focused on mitigating spread of infectious disease at wildland fire incidents to manage both the health of fire personnel and system capacity.

Development and Validation of Earthquake Fire Response Simulation Protocol for Korean College Students in Health Programs.

The purpose of this study is to evaluate the adequacy of the developed protocol by verifying the validity of the expert group for the earthquake and fire response simulation protocol. A protocol development team consisting of one emergency rescue professor, one counseling psychology professor, three paramedics, and one firefighter developed the study’s protocols to promote the core response and capabilities required at an earthquake fire site. We checked the content validity for the appropriateness of the contextual connection for each stage for the protocol. We also created an evaluation checklist to measure the items for each stage. The protocol developed in this study consists of earthquake response, fire response, evacuation, and fire suppression. We set the situation for each stage and composed learner activities and learning performance goals. The earthquake response stage included (1) shout “it’s an earthquake,” (2) protect yourself, (3) turn off electricity and gas, and (4) evacuate to a safe place. In the fire response stage, (1) shout “fire,” (2) press the emergency bell and call 119, (3) close the door of a dangerous place where fire can spread, and (4) evacuate to a safe place. In the evacuation stage, (1) open the emergency exit, (2) cover your nose and mouth, (3) lower your posture, and (4) evacuate quickly in one direction. Lastly, in the firefighting stage, (1) pull out the safety pin, (2) hold the nozzle and face the fire, (3) grab the handle, and (4) spray the powder evenly. The protocol contributes to the development of systematic and elaborate simulation education materials in the future. Furthermore, it provides basic data for future disaster simulation operation and protocol development through continuous training and practical exercises.

Information presentation method for teleoperated robots to support the multifaceted understanding of fire sites

Although the overall number of fires is decreasing, the number of special fires as buildings become larger, taller, and deeper and fires and spills in hazardous materials facilities such as petroleum complexes is on the rise and ensuring the safety of firefighters has become a problem. The use of teleoperated firefighting robots is expected to be a solution to this problem. It is important to be able to operate the robot well, recognize the environment, and make decisions on what actions to take to perform the firefighting more effectively. This is closely related to the design of human machine interface (HMI) for teleoperated robots, but much of the research on HMI for teleoperated robots is concerned with how to operate the robot and how to present the information that is needed for operation. In addition, as the overall number of fires is decreasing, young firefighters' (novices’) lack of experience in firefighting has become a problem. Therefore, teleoperated firefighting robots are required to have the HMI that enables supports to recognize the environment and make decisions in firefighting. This study presents an information presentation method that is based on the control mode in the contextual control model (COCOM) to ensure that novices can have multifaceted perspectives during reconnaissance and attenuation like experienced firefighters (experts). The effectiveness of this method is confirmed by 12 firefighters. As a result, this study confirms that the information presentation is designed considering the control mode in the COCOM, and it improves the score from multiple perspectives. The findings of this study will contribute to the future development of teleoperated firefighting robots.

A GSM and Arduino Based Fire Detection and Control System

Fire alarm and detection systems play a significant role in preventing life and property damages from fire disasters. Many of the existing fire alarm systems could incur significant expense that is not moderate for low-income users. The main purpose of our project is to design and implement a fire detection and control system that can be produced at a low cost at effective and competitive usage with a main objective of saving life and property damages. The system will be able to detect the temperature of the environment, the presence of fire flame, the gas level and send SMS alert to a user through an inbuilt GSM number. The remote user responds to the received fire STATUS information by turning ON/OFF a fire extinguisher or protection equipment installed at the fire site. The system gets power from a 12 V control supply utilizing a step-down transformer; the Arduino Uno Microcontroller is the core part of the system and it is interfaced with the GSM SIM900 module, flame, temperature and smoke sensors and the fire extinguisher equipment. Keywords—Fire Alarm System, Fire-Detector, GSM Module, Arduino UNO Microcontroller, Temperature sensor, Flame sensor, Smoke sensor.

Optimizing the process of fire detection in warehouses considering the type and location of fire detectors

An integral condition for avoiding damage due to fires in warehouses, or at least minimizing them, is the early detection of fires using fire protection systems, as well as its timely localization. Depending on which fire detectors are selected to protect the relevant premises and where they are installed, the time of operation of all elements of automatic control systems in case of a fire will depend. The review of literary data revealed that at present there is no comprehensive approach to choosing the optimal placement in warehouses. In addition, the optimal placement of fire detectors within the room, taking into consideration the type of fire load, has not been sufficiently studied. Therefore, the purpose of the current study is to establish the dependence of the time of operation of different types of fire detectors on the type of combustible material, namely its mass burnout rate, distance, and height of placement of detectors from a potential fire site. This paper reports a procedure for conducting an experimental study to identify the appropriate dependence for warehouses. The results of the experiments showed that the most effective in warehouses are targeted fire smoke detectors and aspiration systems. Based on the results of a complete factor experiment, nonlinear empirical dependences to determine the time of operation of smoke fire detectors on the above factors were built. The resulting empirical dependences make it possible to choose fire detectors and optimally place them within a room. The average error in these dependences when compared with the experimental data is 6.9 %. The use of the derived dependences makes it possible to reduce the time of operation of fire detectors by 14 s in comparison with their placement in accordance with building codes

A Field Study of Tropical Peat Fire Behaviour and Associated Carbon Emissions

Tropical peatlands store vast volumes of carbon belowground. Human land uses have led to their degradation, reducing their carbon storage services. Clearing and drainage make peatlands susceptible to surface and belowground fires. Satellites do not readily detect smouldering peat fires, which release globally significant quantities of aerosols and climate-influencing gases. Despite national and international desire to improve management of these fires, few published results exist for in situ tropical peat fire behaviour and associated carbon emissions. We present new field methodology for calculating rates of fire spread within degraded peat (average spread rates, vertical 0.8 cm h−1, horizontal 2.7 cm h−1) and associated peat volume losses (102 m3 ha−1 in August, 754 m3 ha−1 in September) measured at six peat fire sites in Kalimantan, Indonesia, in 2015. Utilizing locally collected bulk density and emission factors, total August and September gas emissions of 27.2 t ha−1 (8.1 tC ha−1) and 200.7 t ha−1 (60.2 tC ha−1) were estimated. We provide much needed, but currently lacking, IPCC Tier 3-level data to improve GHG estimates from tropical peat fires. We demonstrate how calculations of total emission estimates can vary greatly in magnitude (+798% to −26%) depending on environmental conditions, season, peat burn depth methodology, bulk density and emission factors data sources, and assumed versus observed combustion factors. This illustrates the importance of in situ measurements and the need for more refined methods to improve accuracies of GHG estimates from tropical peat fires.

Design of intelligent fire-fighting robot based on multi-sensor fusion and experimental study on fire scene patrol

Based on the current situation that most fire-fighting robots are operated by humans and do not have independent planning and operation abilities, in this paper an intelligent fire-fighting robot is designed using multi-sensor fusion. The robot has the functions of automatic inspection and fire-fighting, and can integrate the information of the operational environment and make decisions based multi-sensor fusion. An improved path-planning mechanism is proposed in order to overcome some disadvantages of the ant colony optimization algorithm, such as its easy tendency to reach local optimal solutions, slow convergence speed and weak global searching ability. A comprehensive evaluation method of the improved ACO is established to quantify its relevance and effectiveness. A joint calibration scheme for the color and temperature information obtained using an infrared thermal imager and a binocular vision camera was designed, and the internal and external parameters and distortion coefficient of the camera were successfully obtained. Based on the principle of binocular vision, a fire source detection and location strategy is proposed. When a fire source is detected, the location of the fire source is determined quickly and rescue path planning can be carried out, which improves the intelligence level of the fire-fighting robot. Finally, MATLAB and ROS are used to analyze the improved algorithm, and a fire site patrolling experiment is carried out. The results showed that the improved ACO greatly improves the convergence, reduces the number of iterations and greatly shortens the length of the patrol path, while the robot can effectively determine the location of the fire source efficiently during independent patrols and sound alarms, which will save precious time for fire-fighting and emergency rescue personnel.

Fire Detection and Water Discharge Activity for Fire Fighting Robots using IoT

A fire is a calamity that can result in the loss of life, property damage, and the victim's lasting incapacity. Our obstacle remover and fireman Robot has been declared. In the case of a fire, we are compelled to employ human resources, which are not safe, to rescue people and put out the fire. With the advent of technology, particularly in robotics, it is now possible to respond quickly to fire locations and combat fires. This would increase firefighter efficiency while simultaneously preventing them from putting their lives in danger. In this project, we created a prototype robot using Arduino that detects and extinguishes fires autonomously. When the flame sensor detects a fire, the water pump and servo motor are activated. The capacity to detect fire sites automatically and extinguish fire remotely at a distance of 20 cm from the fire. The robot is designed to locate fires and spray water into them in order to decrease the amount of damage.

PFAS in drinking water and serum of the people of a southeast Alaska community: A pilot study

Per- and polyfluoroalkyl substances (PFAS) have become a target of rigorous scientific research due to their ubiquitous nature and adverse health effects. However, there are still gaps in knowledge about their environmental fate and health implications. More attention is needed for remote locations with source exposures. This study focuses on assessing PFAS exposure in Gustavus, a small Alaska community, located near a significant PFAS source from airport operations and fire training sites. Residential water (n = 25) and serum (n = 40) samples were collected from Gustavus residents and analyzed for 39 PFAS compounds. In addition, two water samples were collected from the previously identified PFAS source near the community. Fourteen distinct PFAS were detected in Gustavus water samples, including 6 perfluorinated carboxylic acids (PFCAs), 7 perfluorosulfonic acids (PFSAs), and 1 fluorotelomer sulfonate (FTS). ΣPFAS concentrations in residential drinking water ranged from not detected to 120 ng/L. High ΣPFAS levels were detected in two source samples collected from the Gustavus Department of Transportation (14,600 ng/L) and the Gustavus Airport (228 ng/L), confirming these two locations as a nearby major source of PFAS contamination. Seventeen PFAS were detected in serum and ΣPFAS concentrations ranged from 0.0170 to 13.1 ng/mL (median 0.0823 ng/mL). Perfluorooctanesulfonic acid (PFOS) and perfluorohexanesulfonic acid (PFHxS) were the most abundant PFAS in both water and serum samples and comprised up to 70% of ΣPFAS concentrations in these samples. Spearman's correlation analysis revealed PFAS concentrations in water and sera were significantly and positively correlated (r = 0.495; p = 0.0192). Our results confirm a presence of a significant PFAS source near Gustavus, Alaska and suggest that contaminated drinking water from private wells contributes to the overall PFAS body burden in Gustavus residents.

Working toward a fire-scar network for the Cumberland Plateau—Fire history results from Bridgestone Nature Reserve at Chestnut Mountain, Tennessee1

We reconstructed historical fire regime characteristics at the Bridgestone Nature Reserve at Chestnut Mountain using tree-ring dated fire scars on live and dead shortleaf pine (Pinus echinata Mill.) trees. Fire-scar records described the historical fire frequency and seasonality from the mid-18th century to present. Overall, we found historical fires occurred relatively frequently, predominantly in the dormant season, and were likely low-severity events. Mean fire intervals (MFIs) were slightly longer in the pre-Euro-American period (1744–1834; MFI = 9.6 yrs) versus the post-Euro-American period (1834–1935; MFI = 5.6 yrs). No fires were recorded after 1940, which in combination with past logging and land uses, is likely a major contributor to the ongoing decline of shortleaf pine and pyrophytic oak species observed here. Surprisingly, the majority of fire event years after 1834 were also recorded at Savage Gulf State Natural Area (52 km to the south), raising questions about potential historical fire sizes, patterns, and driving factors across the Cumberland Plateau landscape. In a landscape where fire-scarred remnants are present but relatively scarce and rapidly disappearing, these data are important for evidencing historical fire regimes and developing a more comprehensive regional network of fire history sites that could reveal valuable historical ecological information for the Cumberland Plateau.

Ca2+ signalling in interstitial cells of Cajal contributes to generation and maintenance of tone in mouse and monkey lower oesophageal sphincters.

The lower oesophageal sphincter (LES) generates tone and prevents reflux of gastric contents. LES smooth muscle cells (SMCs) are relatively depolarised, facilitating activation of Cav 1.2 channels to sustain contractile tone. We hypothesised that intramuscular interstitial cells of Cajal (ICC-IM), through activation of Ca2+ -activated Cl- channels (ANO1), set membrane potentials of SMCs favourable for activation of Cav 1.2 channels. In some gastrointestinal muscles, ANO1 channels in ICC-IM are activated by Ca2+ transients, but no studies have examined Ca2+ dynamics in ICC-IM within the LES. Immunohistochemistry and qPCR were used to determine expression of key proteins and genes in ICC-IM and SMCs. These studies revealed that Ano1 and its gene product, ANO1, are expressed in c-Kit+ cells (ICC-IM) in mouse and monkey LES clasp muscles. Ca2+ signalling was imaged in situ, using mice expressing GCaMP6f specifically in ICC (Kit-KI-GCaMP6f). ICC-IM exhibited spontaneous Ca2+ transients from multiple firing sites. Ca2+ transients were abolished by cyclopiazonic acid or caffeine but were unaffected by tetracaine or nifedipine. Maintenance of Ca2+ transients depended on Ca2+ influx and store reloading, as Ca2+ transient frequency was reduced in Ca2+ free solution or by Orai antagonist. Spontaneous tone of LES muscles from mouse and monkey was reduced ∼80% either by Ani9, an ANO1 antagonist or by the Cav 1.2 channel antagonist nifedipine. Membrane hyperpolarisation occurred in the presence of Ani9. These data suggest that intracellular Ca2+ activates ANO1 channels in ICC-IM in the LES. Coupling of ICC-IM to SMCs drives depolarisation, activation of Cav 1.2 channels, Ca2+ entry and contractile tone. KEY POINTS: The lower oesophageal sphincter (LES) generates contractile tone preventing reflux of gastric contents into the oesophagus. LES smooth muscle cells (SMCs) display depolarised membrane potentials facilitating activation of L-type Ca2+ channels. Interstitial cells of Cajal (ICC) express Ca2+ -activated Cl- channels encoded by Ano1 in mouse and monkey LES. Ca2+ signalling in ICC activates ANO1 currents in ICC. ICC displayed spontaneous Ca2+ transients in mice from multiple firing sites in each cell and no entrainment of Ca2+ firing between sites or between cells. Inhibition of ANO1 channels with a specific antagonist caused hyperpolarisation of mouse LES and inhibition of tone in monkey and mouse LES muscles. Our data suggest a novel mechanism for LES tone in which Ca2+ transient activation of ANO1 channels in ICC generates depolarising inward currents that conduct to SMCs to activate L-type Ca2+ currents, Ca2+ entry and contractile tone.