scholarly journals Spatio-temporal variations of cave-air CO2 concentrations in two Croatian show caves: Natural vs. anthropogenic controls

2021 ◽  
Vol 74 (3) ◽  
pp. 273-286
Author(s):  
Maša Surić ◽  
◽  
Robert Lončarić ◽  
Matea Kulišić ◽  
Lukrecija Sršen ◽  
...  
Keyword(s):  
Co2 Flux ◽  
Co2 Concentration ◽  
Temporal Variations ◽  
Natural Processes ◽  
Air Temperatures ◽  
Show Caves ◽  
Spatio Temporal ◽  
Bora Wind ◽  
Carbon Dioxide Co2 ◽  
The Right

Carbon dioxide (CO2) concentration (CDC) plays an important role in karst processes, governing both carbonate deposition and dissolution, affecting not only natural processes, but also human activities in caves adapted for tourism. Its variations due to various controlling parameters was observed from 2017 to 2021 in two Croatian show caves (Manita peć and Modrič) where we examined inter- and within-cave correlation of internal aerology regarding the sources, sinks and transport mechanism of CDC in a karst conduit setting. In both caves, the main sources of CO2 are: i) plant and microbial activity i.e. root respiration and organic matter decay within soil horizons and fractured epikarst, and ii) degassing from CO2-rich percolation water. The main sink of CO2 is dilution with outside air due to cave ventilation. Chimney-effect driven ventilation controlled by seasonal differences between surface and cave air temperatures shows winter (Tout<Tcave) and summer (Tout>Tcave ) ventilation regime, which are modulated by the geometry of cave passages, the transmissivity of the overlying epikarst, and occasionally by the external winds, especially the gusty north-eastern bora wind. In these terms, the Modrič Cave appears to be more confined and less ventilated, with a substantial CDC difference between the left (550-7200 ppm) and right (1475- >10,000 ppm) passages. The Manita peć Cave is, in contrast, ventilated almost year-round, having 7 months of CDC equilibrated with the outside atmosphere and the highest summer CDC values of ~1410 ppm. In both caves, at the current level of tourist use, anthropogenic CO2 flux is not a matter of concern for cave conservation. In turn, in the innermost part of the right Modrič Cave passage visitors’ health might be compromised, but the tourists are allowed only in the left passage. Speleothem growth rate, recognized as a useful palaeoenvironmental proxy for speleothem-based palaeoclimate studies, strongly depends on CDC variations, so the high CDCs recorded in the Modrič Cave indicate the potential periods with no speleothem deposition due to the hampered degassing of CO2 from the dripping groundwater. The opposite effect i.e. enhanced ventilation (that supports calcite precipitation) during the windy glacials/stadials, as well as substantial vegetational changes must also be taken into consideration when interpreting environmental records from spelean calcite.

scholarly journals Spatio-Temporal Validation of AIRS CO2 Observations Using GAW, HIPPO and TCCON

2020 ◽  
Vol 12 (21) ◽  
pp. 3583
Author(s):  
Hui Yang ◽  
Gefei Feng ◽  
Ru Xiang ◽  
Yunjing Xu ◽  
Yong Qin ◽  
...  
Keyword(s):  
Co2 Concentration ◽  
Satellite Observations ◽  
Total Carbon ◽  
Near Surface ◽  
Temporal Validation ◽  
Satellite Sensors ◽  
Spatio Temporal ◽  
The Difference ◽  
Carbon Dioxide Co2

Carbon dioxide (CO2) is a significant atmospheric greenhouse gas and its concentrations can be observed by in situ surface stations, aircraft flights and satellite sensors. This paper investigated the ability of the CO2 satellite observations to monitor, analyze and predict the horizontal and vertical distribution of atmospheric CO2 concentration at global scales. CO2 observations retrieved by an Atmospheric Infrared Sounder (AIRS) were inter-compared with the Global Atmosphere Watch Program (GAW) and HIAPER Pole-to-Pole Observations (HIPPOs), with reference to the measurements obtained using high-resolution ground-based Fourier Transform Spectrometers (FTS) in the Total Carbon Column Observing Network (TCCON) from near-surface level to the mid-to-high troposphere. After vertically integrating the AIRS-retrieved values with the column averaging kernels of TCCON measurements, the AIRS observations are spatio-temporally compared with HIPPO-integrated profiles in the mid-to-high troposphere. Five selected GAW stations are used for comparisons with TCCON sites near the surface of the Earth. The results of AIRS, TCCON (5–6 km), GAW and TCCON (1 km) CO2 measurements from 2007 to 2013 are compared, analyzed and discussed at their respective altitudes. The outcomes indicate that the difference of about 3.0 ppmv between AIRS and GAW or other highly accurate in situ surface measurements is mainly due to the different vertical altitudes, rather than the errors in the AIRS. The study reported here also explores the potential of AIRS satellite observations for analyzing the spatial distribution and seasonal variation of CO2 concentration at global scales.

scholarly journals Environmental Variables of the Seti Gandaki River Basin Pokhara, Nepal

2018 ◽  
Vol 22 (2) ◽  
pp. 129-139 ◽  
Author(s):  
Kishor Kumar Pokharel ◽  
Khadga Bahadur Basnet ◽  
Trilok Chandra Majupuria ◽  
Chitra Bahadur Baniya
Keyword(s):  
Water Temperature ◽  
River Basin ◽  
Environmental Variables ◽  
Temporal Variations ◽  
Total Alkalinity ◽  
Urban Site ◽  
Water Conductivity ◽  
Free Carbon Dioxide ◽  
Spatio Temporal ◽  
Carbon Dioxide Co2

Present paper focuses on the spatio-temporal variations and correlations among the environmental variables of the Seti Gandaki River basin, Pokhara, Nepal. A total of five sites, three along the river and two in tributaries were selected for this study. Water sampling was done fortnightly for environmental variables following standard methods during July 2011 to June 2012. Mean and standard deviation of the environmental variables revealed that the depth (0.9 ± 0.3), pH (8 ± 0.4), total phosphates (PO4) (0.10 ± 0.03) and nitrates (NO3) (0.13 ± 0.04) were normally variable among the sites. But the discharge (40.00 ± 37.00), width (32.30 ± 13.00), turbidity (81.40 ± 51.00), transparency (29.10 ± 15.00), conductivity (166.00 ± 80.00), water temperature (18.00 ±4.00), dissolved oxygen (DO) (8.00 ± 2.00), free carbon dioxide (CO2) (7.00 ± 2.00) and total alkalinity (98.00 ± 22.00) varied among sites equally. Correlation coefficient between the sites and environmental variables revealed that sites were found significantly correlated with water conductivity (r2 = 0.6), DO (r2 = -0.52), and free CO2 (r2 = 0.6); depth of water with width (r2 = 0.94), discharge (r2 = 0.96), turbidity (r2 = 0.71), transparency (r2 = -0.62), water temperature (r2 = 0.60), pH (r2 = -0.52) and DO (r2 = -0.48); water temperature with pH (r2 = -0.54), DO (r2 = -0.79), free CO2 (r2 = 0.69), total alkalinity (r2 = -0.58), total PO4 (r2 = 0.54) and NO3 (r2 = 0.62), etc. The enhancement of turbidity, conductivity, free CO2, phosphates and nitrates, while, suppression of transparency, pH and DO at the urban site indicated the urban influence. Journal of Institute of Science and TechnologyVolume 22, Issue 2, January 2018, page: 129-139

Soil CO2 flux affected by Aporrectodea caliginosa earthworms

2010 ◽  
Vol 5 (3) ◽  
pp. 364-370 ◽  
Author(s):  
Miloslav Šimek ◽  
Václav Pižl
Keyword(s):  
Co2 Emissions ◽  
Co2 Flux ◽  
Co2 Concentration ◽  
Experimental Period ◽  
Aporrectodea Caliginosa ◽  
Soil Co2 Flux ◽  
Soil Air ◽  
Soil Microbial ◽  
Carbon Dioxide Co2 ◽  
Soil Accumulation

AbstractThe effects of Aporrectodea caliginosa earthworms on both carbon dioxide (CO2) accumulation in and emissions from soil, as well as the simultaneous impact of earthworms on soil microbiological properties were investigated in a microcosm experiment carried out over 5.5 months. Concentration of CO2 in soil air was greater at a depth of 15 cm when compared with a depth of 5 cm, but varied during the season both in control and earthworm-inhabited chambers. Peaks of CO2 concentrations at both depths occurred in both treatments during August, approximately 80 days after the experiment started. Generally, the presence of earthworms increased the CO2 concentration at 15-cm depth. Larger CO2 emissions were consistently recorded in conjunction with higher amounts of CO2 in soil air when chambers were inhabited by earthworms. The total CO2 emissions during the experimental period covering 161 days were estimated at 118 g CO2-C m−2 and 99 g CO2-C m−2 from chambers with and without earthworms respectively. Moreover, the presence of earthworms increased microbial biomass in the centre and at the bottom of chambers, and enhanced both dehydrogenase activity and nitrifying enzyme activity in the soils. We suggest that the effect of earthworms on both the enhanced soil accumulation of CO2 as well as emissions of CO2 was mostly indirect, due to the impacts of earthworms on soil microbial community.

scholarly journals Measurements of CO<sub>2</sub> exchange with an automated chamber system throughout the year: challenges in measuring nighttime respiration on porous peat soil

2013 ◽  
Vol 10 (8) ◽  
pp. 14195-14238 ◽  
Author(s):  
M. Koskinen ◽  
K. Minkkinen ◽  
P. Ojanen ◽  
M. Kämäräinen ◽  
T. Laurila ◽  
...  
Keyword(s):  
Friction Velocity ◽  
Peat Soil ◽  
Co2 Flux ◽  
Co2 Concentration ◽  
Chamber System ◽  
Fitting Method ◽  
Starting Point ◽  
Best Fitting ◽  
Flux Estimation ◽  
Carbon Dioxide Co2

Abstract. We built an automatic chamber system to measure greehouse gas (GHG) exchange in forested peatland ecosystems. We aimed to build a system robust enough which would work throughout the year and could measure through a changing snowpackin addition to producing annual GHG fluxes by integrating the measurements without the need of using models. The system worked rather well throughout the year, but it was not service free. Gap filling of data was still necessary. We observed problems in carbon dioxide (CO2) flux estimation during calm summer nights, when a CO2 concentration gradient from soil/moss system to atmosphere builds up. Chambers greatly overestimated the nighttime respiration. This was due to the disturbance caused by the chamber to the soil-moss CO2 gradient and consequent initial pulse of CO2 to the chamber headspace. We tested different flux calculation and measurement methods to solve this problem. The estimated flux was strongly dependent on (1) the type of the fit (linear and polynomial), (2) the starting point of the fit after closing the chamber, (3) the length of the fit, (4) the speed of the fan mixing the air inside the chamber, and (5) atmospheric turbulence (friction velocity, u&amp;ast;). The best fitting method (the most robust, least random variation) was linear fitting with the period of 120–240 s after chamber closure. Furthermore, the fan should be adjusted to spin at minimum speed to avoid the pulse-effect, but it should be kept on to ensure mixing. If nighttime problems cannot be solved, emissions can be estimated using daytime data from opaque chambers.

scholarly journals The BrIdge voLcanic LIdar—BILLI: A Review of Data Collection and Processing Techniques in the Italian Most Hazardous Volcanic Areas

2020 ◽  
Vol 10 (18) ◽  
pp. 6402
Author(s):  
Stefano Parracino ◽  
Simone Santoro ◽  
Luca Fiorani ◽  
Marcello Nuvoli ◽  
Giovanni Maio ◽  
...  
Keyword(s):  
Data Collection ◽  
Co2 Flux ◽  
Volcanic Eruptions ◽  
Co2 Concentration ◽  
Volcanic Hazards ◽  
Volcanic Gases ◽  
Volcanic Gas ◽  
Mt Etna ◽  
Carbon Dioxide Co2 ◽  
Processing Techniques

Volcanologists have demonstrated that carbon dioxide (CO2) fluxes are precursors of volcanic eruptions. Controlling volcanic gases and, in particular, the CO2 flux, is technically challenging, but we can retrieve useful information from magmatic/geological process studies for the mitigation of volcanic hazards including air traffic security. Existing techniques used to probe volcanic gas fluxes have severe limitations such as the requirement of near-vent in situ measurements, which is unsafe for operators and deleterious for equipment. In order to overcome these limitations, a novel range-resolved DIAL-Lidar (Differential Absorption Light Detection and Ranging) has been developed as part of the ERC (European Research Council) Project “BRIDGE”, for sensitive, remote, and safe real-time CO2 observations. Here, we report on data collection, processing techniques, and the most significant findings of the experimental campaigns carried out at the most hazardous volcanic areas in Italy: Pozzuoli Solfatara (Phlegraen Fields), Stromboli, and Mt. Etna. The BrIdge voLcanic LIdar—BILLI has successfully obtained accurate measurements of in-plume CO2 concentration and flux. In addition, wind velocity has also been retrieved. It has been shown that the measurements of CO2 concentration performed by BILLI are comparable to those carried out by volcanologists with other standard techniques, heralding a new era in the observation of long-term volcanic gases.

scholarly journals Deriving a sea surface climatology of CO<sub>2</sub> fugacity in support of air–sea gas flux studies

2014 ◽  
Vol 11 (4) ◽  
pp. 1895-1948 ◽  
Author(s):  
L. M. Goddijn-Murphy ◽  
D. K. Woolf ◽  
P. E. Land ◽  
J. D. Shutler ◽  
C. Donlon
Keyword(s):  
Co2 Flux ◽  
Co2 Concentration ◽  
Sea Surface ◽  
Climate Variables ◽  
Gas Flux ◽  
Concentration Difference ◽  
Surface Measurements ◽  
Thermodynamic Driving Force ◽  
Ocean Carbon ◽  
Carbon Dioxide Co2

Abstract. Climatologies, or long-term averages, of essential climate variables are useful for evaluating models and providing a baseline for studying anomalies. The Surface Ocean Carbon Dioxide (CO2) Atlas (SOCAT) has made millions of global underway sea surface measurements of CO2 publicly available, all in a uniform format and presented as fugacity, fCO2. fCO2 is highly sensitive to temperature and the measurements are only valid for the instantaneous sea surface temperature (SST) that is measured concurrent with the in-water CO2 measurement. To create a climatology of fCO2 data suitable for calculating air–sea CO2 fluxes it is therefore desirable to calculate fCO2 valid for climate quality SST. This paper presents a method for creating such a climatology. We recomputed SOCAT's fCO2 values for their respective measurement month and year using climate quality SST data from satellite Earth observation and then extrapolated the resulting fCO2 values to reference year 2010. The data were then spatially interpolated onto a 1° × 1° grid of the global oceans to produce 12 monthly fCO2 distributions for 2010. The partial pressure of CO2 (pCO2) is also provided for those who prefer to use pCO2. The CO2 concentration difference between ocean and atmosphere is the thermodynamic driving force of the air–sea CO2 flux, and hence the presented fCO2 distributions can be used in air–sea gas flux calculations together with climatologies of other climate variables.

Simulating the Use of CO2 Concentration Inputs for Controlling Temperature in a Hydronic Radiant System

2017 ◽  
Author(s):  
Michael Sterman ◽  
Melody Baglione
Keyword(s):  
High Performance ◽  
Energy Use ◽  
Numerical Models ◽  
Co2 Concentration ◽  
Ann Model ◽  
Heating And Cooling ◽  
Air Temperatures ◽  
Demand Fluctuations ◽  
Carbon Dioxide Co2 ◽  
And Control

Incorporating predictive control into heating, ventilation and air conditioning (HVAC) systems has the potential to improve occupancy comfort and reduce energy use. This paper simulates the novel use of carbon dioxide (CO2) concentration inputs to augment temperature prediction and control. An artificial neural network (ANN) model and a least mean squares (LMS) filtering algorithm are used to simulate the temperature and control of a classroom in a high performance academic building with hydronic radiant heating and cooling panels. Numerical models are populated with variables that affect the heat energy entering, leaving, and being generated in a classroom. These variables include indoor and outdoor air temperature, radiant water and supply air temperatures, and classroom CO2 concentrations. The models are compared and then used to simulate the effect of a new control system that inputs CO2 measurements to account for the heat being generated by occupants of the controlled space. Simulation results suggest that augmenting HVAC control systems with CO2 measurements has the potential to improve temperature regulation by anticipating heating and cooling demand fluctuations in spaces with abrupt changes in occupancy.

scholarly journals Additions of Tropospheric Ozone (O3) in Regional Climates (A case study: Saudi Arabia)

2019 ◽  
Vol 01 (01) ◽  
Author(s):  
Syed Shehzad Hassan ◽  
Maham Mukhtar ◽  
Ehsan ul Haq ◽  
Muneeb Aamir ◽  
Hafiz M Rafique ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Saudi Arabia ◽  
Sulfur Dioxide ◽  
Nitrogen Dioxide ◽  
Optical Depth ◽  
Anthropogenic Activities ◽  
Temporal Variations ◽  
Vertical Column ◽  
Spatio Temporal ◽  
Carbon Dioxide Co2

Anthropogenic activities are responsible for enhancing the concentration of various toxic gases that produces bad Ozone in the troposphere which is harmful to human health. The specific objective of this research was to analyze the spatio-temporal variations in a vertical column of Ozone (O3) over Saudi Arabia during 2006-2016 using Atmospheric Infrared Sounder (AIRS) onboard AQUA platform and AErosol RObotic NETwork (AERONET) data. The results show that the optical depth of Ozone column varied from 252 Dobson Units (DU) to 264 DU. The main reason of this variation corresponds to the increase in O3 precursors including Carbon Dioxide (CO2), Nitrogen Dioxide (NO2) and Sulfur Dioxide (SO2). The concentration of CO2 varied between (379-401) Parts Per Million (PPM), SO2 varied (3.5x10-6 - 4x10-6kg m-2) kg m-2 and NO2 varies (2.25x1015 - 2.5x1015)1/cm2 during the investigated timeframe. The results confirm that NO2 and SO2 have contributed directly in O3 formation while CO2 just increased regional temperatures that enhanced the optical depth of O3. Keywords: AIRS, AERONET, Carbon dioxide, Nitrogen dioxide, Sulfur dioxide, Aerosol optical depth and Dopson Unit.

scholarly journals Spatio–Temporal Characterization of Land Surface Air Temperature Anomaly over Nigeria

2019 ◽  
pp. 1-9
Author(s):  
O. O. Ajileye ◽  
S. S. Aladodo ◽  
A. B. Rabiu
Keyword(s):  
Air Temperature ◽  
Land Surface ◽  
Temperature Anomaly ◽  
Surface Air Temperature ◽  
Temporal Variations ◽  
Capital City ◽  
Percentage Increase ◽  
Air Temperatures ◽  
Spatio Temporal ◽  
Air Temperature Anomaly

In this study, seventeen gridded stations across the latitude over Nigeria were selected with a view to determine and characterize land surface air temperature anomaly for both minimum and maximum values. The study intends to present graphic illustrations of spatial and temporal variations of land surface air temperature anomaly within a period 2008 – 2013. Long-term averages of minimum and maximum land surface air temperatures were obtained from National Aeronautic and Space Administration satellite meteorological dataset (1983 – 2007). Also, monthly and annual averages of land surface air temperatures were obtained from tutiempo.net to compute monthly anomaly, annual anomaly and percentage departure of minimum and maximum land surface air temperatures within a period of 2008 – 2013. The results showed that Jos had consistently experienced -10.8 and -4 percent decrease in minimum and maximum LSAT anomaly for the period under review. The implication is that Jos is getting colder than usual. The minimum LSAT anomaly declined by -2.8 percent in Lagos. Other stations across Nigeria showed a considerable percentage increase in minimum LSAT anomaly led by Yola (19.5%), Sokoto (18%) and Katsina (15.5%). Inland stations had percentage increase of minimum LSAT anomaly ranging between 5.8% and 10% except in Osogbo where the percentage increase was 1.8%. Osogbo is a less populated capital city of Osun state with active agricultural activities as heat sink. Percentage increase of minimum LSAT anomaly was not significant in Nigerian coastal areas most especially at Port Harcourt (0.5%). The spatial distribution of maximum LSAT anomaly across Nigerian latitudinal belt, unlike minimum LSAT anomaly, reduced in trend except in Lagos, Makurdi, Abuja, Bida, Minna and Kano. The minimum and maximum anomaly for maximum LSAT was observed at Jos and Makurdi respectively. There are 2 stations to be watched in terms of getting colder in the years to ahead namely Jos and Osogbo while Makurdi and Yola are gradually becoming hotspots.

scholarly journals Analysis of CO<sub>2</sub> spatio-temporal variations in China using a weather–biosphere online coupled model

2021 ◽  
Vol 21 (9) ◽  
pp. 7217-7233
Author(s):  
Xinyi Dong ◽  
Man Yue ◽  
Yujun Jiang ◽  
Xiao-Ming Hu ◽  
Qianli Ma ◽  
...  
Keyword(s):  
Ecosystem Respiration ◽  
Thermal Structure ◽  
Coupled Model ◽  
Correlation Coefficients ◽  
Co2 Concentration ◽  
Temporal Variations ◽  
Atmospheric Co2 ◽  
Spatio Temporal ◽  
Emission Growth ◽  
Photosynthesis And Respiration

Abstract. The dynamics of atmospheric CO2 has received considerable attention in the literature, yet significant uncertainties remain within the estimates of contribution from the terrestrial flux and the influence of atmospheric mixing. In this study we apply the WRF-Chem model configured with the Vegetation Photosynthesis and Respiration Model (VPRM) option for biomass fluxes in China to characterize the dynamics of CO2 in the atmosphere. The online coupled WRF-Chem model is able to simulate biosphere processes (photosynthetic uptake and ecosystem respiration) and meteorology in one coordinate system. We apply WRF-Chem for a multi-year simulation (2016–2018) with integrated data from a satellite product, flask samplings, and tower measurements to diagnose the spatio-temporal variations of CO2 fluxes and concentrations in China. We find that the spatial distribution of CO2 was dominated by anthropogenic emissions, while its seasonality (with maxima in April 15 ppmv higher than minima in August) was dominated by the terrestrial flux and background CO2. Observations and simulations revealed a consistent increasing trend in column-averaged CO2 (XCO2) of 2.46 ppmv (0.6 % yr−1) resulting from anthropogenic emission growth and biosphere uptake. WRF-Chem successfully reproduced ground-based measurements of surface CO2 concentration with a mean bias of −0.79 ppmv and satellite-derived XCO2 with a mean bias of 0.76 ppmv. The model-simulated seasonality was also consistent with observations, with correlation coefficients of 0.90 and 0.89 for ground-based measurements and satellite data, respectively. Tower observations from a background site at Lin'an (30.30∘ N, 119.75∘ E) revealed a strong correlation (−0.98) between vertical CO2 and temperature gradients, suggesting a significant influence of boundary layer thermal structure on the accumulation and depletion of atmospheric CO2.

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