scholarly journals Biogeochemical and biophysical responses to episodes of wildfire smoke from natural ecosystems in southwestern British Columbia, Canada

2021 ◽  
Author(s):  
Sung-Ching Lee ◽  
Sara H. Knox ◽  
Ian McKendry ◽  
T. Andrew Black
Keyword(s):  
Observational Studies ◽  
Natural Experiment ◽  
Fire Severity ◽  
Fire Season ◽  
Natural Ecosystems ◽  
Diffuse Fraction ◽  
Wildfire Smoke ◽  
Carbon Dioxide Co2 ◽  
Eddy Covariance Measurement

Abstract. Area burned, number of fires, seasonal fire severity, and fire season length are all expected to increase in Canada, with largely unquantified ecosystem feedbacks. However, there are few observational studies measuring the ecosystem‐scale biogeochemical and biophysical properties during smoke episodes, and hence accessing productivity effects of changes in incident diffuse photosynthetically active radiation (PAR). In this study, we leverage two long-term eddy covariance measurement sites in forest and wetland to study four smoke episodes, which happened at different times and differed in length, over four different years. We found that the highest decrease of shortwave irradiance due to smoke was about 50 % in July and August but increased to about 90 % when the smoke arrived in September. When the smoke arrived in the later stage of summer, impacts on H and LE were also greatest. Smoke generally increased the diffuse fraction from ~0.30 to ~0.50 and turned both sites into stronger carbon-dioxide (CO2) sinks with increased productivity of ~18 % and ~7 % at the forest and wetland sites, respectively. However, when the diffuse fraction exceeded 0.80 as a result of dense smoke, both ecosystems became CO2 sources as total PAR dropped to low values. The results suggest that this kind of natural experiment is important for validating future predictions of smoke‐productivity feedbacks.

scholarly journals Semi-Analytical Solution to Assess CO2 Leakage in the Subsurface through Abandoned Wells

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2452
Author(s):  
Tian Qiao ◽  
Hussein Hoteit ◽  
Marwan Fahs
Keyword(s):  
Analytical Solution ◽  
Storage Site ◽  
Co2 Leakage ◽  
Transient Pressure ◽  
Flow Paths ◽  
Abandoned Wells ◽  
Diffusivity Equation ◽  
Carbon Dioxide Co2 ◽  
Good Agreement

Geological carbon storage is an effective method capable of reducing carbon dioxide (CO2) emissions at significant scales. Subsurface reservoirs with sealing caprocks can provide long-term containment for the injected fluid. Nevertheless, CO2 leakage is a major concern. The presence of abandoned wells penetrating the reservoir caprock may cause leakage flow-paths for CO2 to the overburden. Assessment of time-varying leaky wells is a need. In this paper, we propose a new semi-analytical approach based on pressure-transient analysis to model the behavior of CO2 leakage and corresponding pressure distribution within the storage site and the overburden. Current methods assume instantaneous leakage of CO2 occurring with injection, which is not realistic. In this work, we employ the superposition in time and space to solve the diffusivity equation in 2D radial flow to approximate the transient pressure in the reservoirs. Fluid and rock compressibilities are taken into consideration, which allow calculating the breakthrough time and the leakage rate of CO2 to the overburden accurately. We use numerical simulations to verify the proposed time-dependent semi-analytical solution. The results show good agreement in both pressure and leakage rates. Sensitivity analysis is then conducted to assess different CO2 leakage scenarios to the overburden. The developed semi-analytical solution provides a new simple and practical approach to assess the potential of CO2 leakage outside the storage site. This approach is an alternative to numerical methods when detailed simulations are not feasible. Furthermore, the proposed solution can also be used to verify numerical codes, which often exhibit numerical artifacts.

scholarly journals Behavioral medicine challenges in the shadow of a global pandemic

2020 ◽  
Author(s):  
Alyssa T Brooks ◽  
Hannah K Allen ◽  
Louise Thornton ◽  
Tracy Trevorrow
Keyword(s):  
Environmental Factors ◽  
Health Behavior ◽  
Health Behaviors ◽  
Natural Experiment ◽  
Direct Effects ◽  
Global Pandemic ◽  
Wide Range ◽  
Future Data ◽  
Short And Long Term

Abstract Health behavior researchers should refocus and retool as it becomes increasingly clear that the challenges of the COVID-19 pandemic surpass the direct effects of COVID-19 and include unique, drastic, and ubiquitous consequences for health behavior. The circumstances of the pandemic have created a natural experiment, allowing researchers focusing on a wide range of health behaviors and populations with the opportunity to use previously collected and future data to study: (a) changes in health behavior prepandemic and postpandemic, (b) health behavior prevalence and needs amidst the pandemic, and (c) the effects of the pandemic on short- and long-term health behavior. Our field is particularly challenged as we attempt to consider biopsychosocial, political, and environmental factors that affect health and health behavior. These realities, while daunting, should call us to action to refocus and retool our research, prevention, and intervention efforts

scholarly journals Reproductive Performance Following Hysteroscopic Surgery for Uterine Septum: Results from a Single Surgeon Data

2021 ◽  
Vol 10 (1) ◽  
pp. 130
Author(s):  
Ertan Saridogan ◽  
Mona Salman ◽  
Lerzan Sinem Direk ◽  
Ali Alchami
Keyword(s):  
Reproductive Performance ◽  
Observational Studies ◽  
Patient Characteristics ◽  
Reproductive Outcomes ◽  
Hysteroscopic Surgery ◽  
High Quality Evidence ◽  
Study Results ◽  
Significant Difference ◽  
Uterine Septum

Uterine septum can negatively affect reproductive outcomes in women. Based on evidence from retrospective observational studies, hysteroscopic incision has been considered a solution to improve reproductive performance, however there has been recent controversy on the need for surgery for uterine septum. High quality evidence from prospective studies is still lacking, and until it is available, experts are encouraged to publish their data. We are therefore presenting our data that involves analysis of the patient characteristics, surgical approach and long-term reproductive outcomes of women who received treatment for uterine septum under the care of a single surgeon. This includes all women (99) who underwent hysteroscopic surgery for uterine septum between January 2001 and December 2019. Of those 99 women treated for intrauterine septum who were trying to conceive, 91.4% (64/70) achieved pregnancy, 78.6% (55/70) had live births and 8.6% (6/70) had miscarriages. No statistically significant difference was found in the live birth rates when data was analyzed in subgroups based on age, reason for referral/aetiology and severity of pathology. Our study results support the view that surgical treatment of uterine septa is beneficial in improving reproductive outcomes.

scholarly journals Predicting wildfire impacts on the prehistoric archaeological record of the Jemez Mountains, New Mexico, USA

Fire Ecology ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Megan M. Friggens ◽  
Rachel A. Loehman ◽  
Connie I. Constan ◽  
Rebekah R. Kneifel
Keyword(s):  
New Mexico ◽  
Fire Severity ◽  
Fire Effects ◽  
Burn Severity ◽  
Fire Season ◽  
Archaeological Sites ◽  
Archaeological Record ◽  
Human Environment ◽  
Jemez Mountains ◽  
Archaeological Materials

Abstract Background Wildfires of uncharacteristic severity, a consequence of climate changes and accumulated fuels, can cause amplified or novel impacts to archaeological resources. The archaeological record includes physical features associated with human activity; these exist within ecological landscapes and provide a unique long-term perspective on human–environment interactions. The potential for fire-caused damage to archaeological materials is of major concern because these resources are irreplaceable and non-renewable, have social or religious significance for living peoples, and are protected by an extensive body of legislation. Although previous studies have modeled ecological burn severity as a function of environmental setting and climate, the fidelity of these variables as predictors of archaeological fire effects has not been evaluated. This study, focused on prehistoric archaeological sites in a fire-prone and archaeologically rich landscape in the Jemez Mountains of New Mexico, USA, identified the environmental and climate variables that best predict observed fire severity and fire effects to archaeological features and artifacts. Results Machine learning models (Random Forest) indicate that topography and variables related to pre-fire weather and fuel condition are important predictors of fire effects and severity at archaeological sites. Fire effects were more likely to be present when fire-season weather was warmer and drier than average and within sites located in sloped, treed settings. Topographic predictors were highly important for distinguishing unburned, moderate, and high site burn severity as classified in post-fire archaeological assessments. High-severity impacts were more likely at archaeological sites with southern orientation or on warmer, steeper, slopes with less accumulated surface moisture, likely associated with lower fuel moistures and high potential for spreading fire. Conclusions Models for predicting where and when fires may negatively affect the archaeological record can be used to prioritize fuel treatments, inform fire management plans, and guide post-fire rehabilitation efforts, thus aiding in cultural resource preservation.

Spatial and temporal variations of fire regimes in the Canadian Rocky Mountains and Foothills of southern Alberta

2016 ◽  
Vol 25 (11) ◽  
pp. 1117 ◽  
Author(s):  
Marie-Pierre Rogeau ◽  
Mike D. Flannigan ◽  
Brad C. Hawkes ◽  
Marc-André Parisien ◽  
Rick Arthur
Keyword(s):  
Rocky Mountains ◽  
Fire History ◽  
Fire Severity ◽  
Ecological Integrity ◽  
Fire Regimes ◽  
Temporal Variations ◽  
Fire Season ◽  
Canadian Rocky Mountains ◽  
Southern Alberta ◽  
Fire Exclusion

Like many fire-adapted ecosystems, decades of fire exclusion policy in the Rocky Mountains and Foothills natural regions of southern Alberta, Canada are raising concern over the loss of ecological integrity. Departure from historical conditions is evaluated using median fire return intervals (MdFRI) based on fire history data from the Subalpine (SUB), Montane (MT) and Upper Foothills (UF) natural subregions. Fire severity, seasonality and cause are also documented. Pre-1948 MdFRI ranged between 65 and 85 years in SUB, between 26 and 35 years in MT and was 39 years in UF. The fire exclusion era resulted in a critical departure of 197–223% in MT (MdFRI = 84–104 years). The departure in UF was 170% (MdFRI = 104 years), while regions of continuous fuels in SUB were departed by 129% (MdFRI = 149 years). The most rugged region of SUB is within its historical range of variation with a departure of 42% (MdFRI = 121 years). More mixed-severity burning took place in MT and UF. SUB and MT are in a lightning shadow pointing to a predominance of anthropogenic burning. A summer fire season prevails in SUB, but occurs from spring to fall elsewhere. These findings will assist in developing fire and forest management policies and adaptive strategies in the future.

Landscape-scale disturbances and regeneration in semi-arid woodlands of southwestern Australia

1994 ◽  
Vol 1 (3) ◽  
pp. 214 ◽  
Author(s):  
Colin J. Yates ◽  
Richard J. Hobbs ◽  
Richard W. Bell
Keyword(s):  
Tree Mortality ◽  
Landscape Scale ◽  
Eucalyptus Species ◽  
Natural Ecosystems ◽  
Fragmented Landscapes ◽  
The Past ◽  
Adult Tree ◽  
Western Australian ◽  
Semi Arid

Woodlands dominated by Eucalyptus salmonophloia occur both in the fragmented landscapes of the Western Australian wheatbelt and in the adjacent unfragmented goldfields area. We examined the responses of the unfragmented woodlands to landscape-scale disturbances caused by fire, floods, windstorms and drought. Sites known to have experienced disturbances of these types over the past 50 years all had cohorts of sapling-stage E. salmonophloia and other dominant Eucalyptus species. Sites disturbed either by fire, flood or storm during 1991-92 displayed adult tree mortality and extensive seedling establishment, although rates of establishment and survival varied between sites. No regeneration was observed at equivalent undisturbed sites. These results indicate that landscape-scale disturbances of several types are important drivers of the dynamics of these semi-arid woodlands. Lack of regeneration of fragmented woodlands in the wheatbelt is likely to be due to changed disturbance regimes coupled with altered physical and biotic conditions within remnants. We argue that it may be difficult to identify processes which are important for the long-term persistence of natural ecosystems in fragmented landscapes without reference to equivalent unfragmented areas.

Measuring complex for monitoring carbon dioxide in air

2021 ◽  
pp. 68-71
Author(s):  
Igor M. Ageev ◽  
Yuri M. Rybin
Keyword(s):  
Carbon Dioxide ◽  
High Selectivity ◽  
Distilled Water ◽  
Measuring Systems ◽  
Advantages And Disadvantages ◽  
Measuring Complex ◽  
Co2 Level ◽  
Carbon Dioxide Co2 ◽  
Term Monitoring

The advantages and disadvantages of infrared and electrochemical gas analyzers for carbon dioxide CO2 are described. The possibility of using conductometric sensors with distilled water for monitoring the CO2 content in the air has been investigated. Two identical measuring systems were manufactured, each containing two open-type conductometric cells, a matching device and a personal computer. With the help of these complexes, experiments were carried out on the simultaneous measurement of the CO2 content in the air in two places (a laboratory room and a building in a forest, located at a distance of 15 km from each other) with deliberately different daily dynamics of the CO2 level change. A special experiment was carried out, which made it possible to obtain an estimate of the inertia of conductometric cells and a conversion factor for the values of CO2 content into standard units of measurement. It is shown that the daily dynamics of changes in the electrical conductivity of distilled water in open cells corresponds to the expected dynamics of changes in the CO2 content in the rooms where the measurements were carried out. The operability of the measuring complex and the possibility of creating on its basis a device for long-term monitoring of the CO2 content in the air mixture of gases has been confirmed. The principal high selectivity of the measuring complex to CO2 in relation to other gases of the atmosphere has been established.

scholarly journals Update on GOSAT TANSO-FTS performance, operations, and data products after more than 6 years in space

2016 ◽  
Vol 9 (6) ◽  
pp. 2445-2461 ◽  
Author(s):  
Akihiko Kuze ◽  
Hiroshi Suto ◽  
Kei Shiomi ◽  
Shuji Kawakami ◽  
Makoto Tanaka ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Near Infrared ◽  
Satellite System ◽  
Fourier Transform Spectrometer ◽  
Infrared Sensor ◽  
Data Set ◽  
Dry Air ◽  
Retrieval Accuracy ◽  
Carbon Dioxide Co2

Abstract. A data set containing more than 6 years (February 2009 to present) of radiance spectra for carbon dioxide (CO2) and methane (CH4) observations has been acquired by the Greenhouse gases Observing SATellite (GOSAT, available at http://data.gosat.nies.go.jp/GosatUserInterfaceGateway/guig/GuigPage/open.do), nicknamed “Ibuki”, Thermal And Near infrared Sensor for carbon Observation Fourier Transform Spectrometer (TANSO-FTS). This paper provides updates on the performance of the satellite and TANSO-FTS sensor and describes important changes to the data product, which has recently been made available to users. With these changes the typical accuracy of retrieved column-averaged dry air mole fractions of CO2 and CH4 (XCO2 and XCH4, respectively) are 2 ppm or 0.5 % and 13 ppb or 0.7 %, respectively. Three major anomalies of the satellite system affecting TANSO-FTS are reported: a failure of one of the two solar paddles in May 2014, a switch to the secondary pointing system in January 2015, and most recently a cryocooler shutdown and restart in August 2015. The Level 1A (L1A) (raw interferogram) and the Level 1B (L1B) (radiance spectra) of version V201 described here have long-term uniform quality and provide consistent retrieval accuracy even after the satellite system anomalies. In addition, we discuss the unique observation abilities of GOSAT made possible by an agile pointing mechanism, which allows for optimization of global sampling patterns.

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