Greenhouse Gas Measurements Research Articles

Fluxes of CO2, CH4, and N2O in tundra-covered and Nothofagus forest soils in the Argentinian Patagonia

While most soils in periglacial environments present high fluxes of CO2 (FCO2), CH4 (FCH4), and N2O (FN2O), few of them have a tendency to drain greenhouse gases from the atmosphere. This study aimed to assess greenhouse gas fluxes at different sub-Antarctic sites and time periods (at the beginning of thaw and height of summer). To investigate the time of year effect on greenhouse gas emissions, FCO2, FCH4, and FN2O were measured at two sites tundra-covered (Ti and Th) and Nothofagus forest soil (Nf) on Monte Martial, at the southernmost tip of South America, Tierra del Fuego, Argentina. FCO2 ranged from 96.33 to 225.72 μg CO2 m−2 s−1 across all sites and periods, showing a positive correlation with soil temperature (Ts) (4.1 and 8.2 °C, respectively) (r2 > 0.7; p < 0.05). The highest values of FCO2 were found at Ti and Th (728.2 and 662.64 μg CO2 m−2 s−1, respectively), which were related to higher temperatures (8.2 and 8.6 °C, respectively) when compared to those of Nf. For FCH4, the capture (drain) occurred during both periods at Nf (−26 and −79 μg C–CH4 m−2 h−1) as well as Ti and Th (−21 and 12 μg C–CH4 m−2 h−1, respectively). FN2O also presented low values during both periods and showed a tendency to drain N2O from the atmosphere, especially at Nf (−2 μg N–N2O m−2 h−1). In addition, FN2O was slightly positive for Ti and Th (0.3 and 0.55 μg N–N2O m−2 h−1, respectively). Soil moisture did not show a correlation (p > 0.05) with the measured greenhouse gas fluxes. A scenario of increased temperatures might result in changes in the balance between the emissions and drains of these gases from soils, leading to higher emission values of CH4 and N2O, especially for tundra covered soils (Ti and Th), where the highest average fluxes and thermohydric variations were observed over the year.

Synthetic Zero Air Reference Material for High Accuracy Greenhouse Gas Measurements.

The purity analysis of zero air is a significant contributor to the uncertainty in preparing reference materials of high impact greenhouse gases, limiting progress toward coherent and comparable measurements required to assess climate trends. We have produced a commutable synthetic zero air reference material with an oxygen, nitrogen, and argon matrix closely matching atmospheric composition. This is the critical step in preventing systematic biases from pressure broadening effects when using these reference materials to calibrate instruments based on optical spectroscopy. The amount fractions of carbon dioxide, methane, and carbon monoxide, which are present as minor impurities in the zero air reference material, have been accurately quantified using a novel dilution device that can generate gas mixtures of these components at trace amount fractions. These developments will have a significant impact on advancing the state of the art in high accuracy reference materials and for baseline calibration of spectroscopic instrumentation.

LISA: a lightweight stratospheric air sampler

Abstract. We developed a new lightweight stratospheric air sampler (LISA). The LISA sampler is designed to collect four bag samples in the stratosphere during a balloon flight for CO2, CH4 and CO mole fraction measurements. It consists of four multi-layer foil (MLF) sampling bags, a custom-made manifold, and a diaphragm pump, with a total weight of ∼2.5 kg. A series of laboratory storage tests were performed to assess the stability of CO2, CH4 and CO mole fractions in both MLF and Tedlar bags. The MLF bag was chosen due to its better overall performance than the Tedlar bag for the three species CO2, CH4 and CO. Furthermore, we evaluated the performance of the pump under low pressure conditions to optimize a trade-off between the vertical resolution and the sample size. The LISA sampler was flown on the same balloon flight with an AirCore in Sodankylä, Finland (67.368∘ N, 26.633∘ E, 179 m a.s.l.), on 26 April and 4–7 September 2017. A total of 15 stratospheric air samples were obtained during the ascent of four flights. The sample size ranges between 800 and 180 mL for the altitude between 12 and 25 km, with the corresponding vertical resolution ranging from 0.5 to 1.5 km. The collected air samples were analysed for CO2, CH4 and CO mole fractions, and evaluated against AirCore retrieved profiles, showing mean differences of 0.84 ppm for CO2, 1.8 ppb for CH4 and 6.3 ppb for CO, respectively. High-accuracy stratospheric measurements of greenhouse gas mole fractions are useful to validate remote sensing measurements from ground and from space, which has been performed primarily by comparison with collocated aircraft measurements (0.15–13 km), and more recently with AirCore observations (0–30 km). While AirCore is capable of achieving high-accuracy greenhouse gas mole fraction measurements, it is challenging to obtain accurate altitude registration for AirCore measurements. The LISA sampler provides a viable low-cost tool for retrieving stratospheric air samples for greenhouse gas measurements that is complementary to AirCore. Furthermore, the LISA sampler is advantageous in both the vertical resolution and sample size for performing routine stratospheric measurements of the isotopic composition of trace gases.

Direct and indirect carbon emissions in foundation construction – Two case studies of driven precast and cast-in-situ piles

Precast technique has gained significant reputation in the construction industry due to improved efficiency and reduced construction waste. Pile foundation is often built through driven precast or cast-in-situ construction technique. The two types of pile foundations have been widely utilised in various building construction types. The selection of the piling methods has been largely based on the project scope, soil conditions and availability of resources. However, little research has been conducted on environmental impacts brought by driven precast piles compared to cast-in-situ bored piles. The paper aims to address the research gap by conducting a comparative study to measure greenhouse gas (GHG) emissions of driven precast and cast-in-situ piles construction using two case studies in China. A process-based quantification model is developed to measure the major emissions and impacts due to materials, transportation and equipment usage. Results of the study indicated 113.04 and 107.46 kgCO2 per pile per metre of excavated depth for case study A and B respectively. Results of the study also observed a reduction for equipment usage and an increase for transportation in GHG emissions for driven precast piles as compared to cast-in-situ piles. Four scenarios were selected to further investigate the GHG emissions variation. Results indicated that use of sustainable materials can achieve the maximum GHG emissions reduction for both types of pile construction. Transportation distance was recorded as a key factor to be considered in reducing GHG emissions for driven precast piles construction. Results of the study can be effectively utilised to compare life cycle GHG emissions of precast construction with cast-in-situ construction.

Site-specific carbon footprints of Scandinavian wastewater treatment plants, using the life cycle assessment approach

The carbon footprints of seven wastewater treatment plants using different technologies in Denmark and Sweden were evaluated. The life cycle assessment approach was applied by using site-specific data including measured plant-integrated methane and nitrous oxide emissions. Four different functional units were adopted: 1 Mg of input material entering the wastewater treatment plant in 2015, and the removal of 1 kg of carbon, total nitrogen and phosphorus. The net carbon footprint values found in this study were between 0.15 and 0.66 kg CO2 eq (Mg of input material)−1 depending on the treatment facility. Direct greenhouse gas emissions were the main contributors to the carbon footprint, accounting for between 44 and 71% of the total burden. The remaining share of the total burden (66 and 29%) was mainly made by energy consumption, chemicals used, and emissions from effluent and land application of biosolids. Direct greenhouse gas emissions were very sensitive model parameters driving result uncertainties. When default values from emission reporting guidelines were applied instead of measured greenhouse gas emission rates, the net carbon footprint was up to four times smaller or seven times larger. The consumption of electricity from the energy grid for plant operation had a great impact on the carbon footprint, due to differences between the energy systems. The share of electricity consumption to the total carbon footprint burden for the Swedish plants was only 2%, whereas it was between 16 and 28% for the Danish plants. This difference was due to the smaller carbon footprint potential of the electricity mix in Sweden than in Denmark. Normalisation of the carbon footprint to the plant pollution load, and the calculation of model uncertainty, allowed for a reliable comparison of plants operating within the same energy system. Finally, suggestions were provided for performing a sound carbon footprint evaluation of wastewater treatment plants.

Are secondary forests second-rate? Comparing peatland greenhouse gas emissions, chemical and microbial community properties between primary and secondary forests in Peninsular Malaysia

Tropical peatlands are globally important ecosystems with high C storage and are endangered by anthropogenic disturbances. Microbes in peatlands play an important role in sustaining the functions of peatlands as a C sink, yet their characteristics in these habitats are poorly understood. This research aimed to elucidate the responses of these complex ecosystems to disturbance by exploring greenhouse gas (GHG) emissions, nutrient contents, soil microbial communities and the functional interactions between these components in a primary and secondary peat swamp forest in Peninsular Malaysia. GHG measurements using closed chambers, and peat sampling were carried out in both wet and dry seasons. Microbial community phenotypes and nutrient content were determined using phospholipid fatty acid (PLFA) and inductively-coupled plasma mass spectrometry (ICP-MS) analyses respectively. CO2 emissions in the secondary peat swamp forest were > 50% higher than in the primary forest. CH4 emission rates were ca. 2 mg m−2 h−1 in the primary forest but the secondary forest was a CH4 sink, showing no seasonal variations in GHG emissions. Almost all the nutrient concentrations were significantly lower in the secondary forest, postulated to be due to nutrient leaching via drainage and higher rates of decomposition. Cu and Mo concentrations were negatively correlated with CO2 and CH4 emissions respectively. Microbial community structure was overwhelmingly dominated by bacteria in both forest types, however it was highly sensitive to land-use change and season. Gram-positive and Gram-negative relative abundance were positively correlated with CO2 and CH4 emissions respectively. Drainage related disturbances increased CO2 emissions, by reducing the nutrient content including some with known antimicrobial properties (Cu & Na) and by favouring Gram-positive bacteria over Gram-negative bacteria. These results suggest that the biogeochemistry of secondary peat swamp forest is fundamentally different from that of primary peat swamp forest, and these differences have significant functional impacts on their respective environments.

Energy calibration of integrated path differential absorption lidars.

The stringent requirements for energy reference measurement represent a challenging task for integrated path differential absorption lidars to measure greenhouse gas columns from satellite or aircraft. The coherence of the lidar transmitter gives rise to speckle effects that have to be considered for accurate monitoring of the energy ratio of outgoing on- and off-line pulses. Detailed investigations have been performed on various measurement concepts potentially suited for deployment within future satellite missions.

SI traceability and scales for underpinning atmospheric monitoring of greenhouse gases

Metrological traceability is the property of a measurement result whereby it can be related to a stated reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty. The stated reference can be the International System of Units, and more specifically a realisation of a primary standard with its value and uncertainty expressed in SI units, which offers many benefits such as long term stability and the ability to reproduce the standard within its stated uncertainty at any time. Alternatively, measurements can be made traceable to an empirical scale, an approach that has evolved for practical reasons to meet the needs of certain measurement communities. We explore the benefits and drawbacks of these two measurements systems as they have evolved for greenhouse gas measurements at background levels and outline the advantages of using elements from each to secure a more robust measurement infrastructure. In particular, this work examines the importance of compatibility, the accuracy of measurement results and the benefits of comparisons with independent primary standards.

Assessment of Methane and Nitrous Oxide Fluxes from Paddy Field by Means of Static Closed Chambers Maintaining Plants Within Headspace

This protocol describes the measurement of greenhouse gas (GHG) emissions from paddy soils using the static closed chamber technique. This method is based on the diffusion theory. A known volume of air overlaying a defined soil area is enclosed within a parallelepiped cover (named "chamber"), for a defined period of time. During this enclosure period, gases (methane (CH4) and nitrous oxide (N2O)) move from soil pore air near their microbial source (i.e., methanogens, nitrifiers, denitrifiers) to the chamber headspace, following a natural concentration gradient. Fluxes are then estimated from chamber headspace concentration variations sampled at regular intervals throughout the enclosure and then analyzed with gas chromatography. Among the techniques available for GHG measurement, the static closed chamber method is suitable for plot experiments, as it does not require large homogenously treated soil areas. Furthermore, it is manageable with limited resources and can identify relationships among ecosystem properties, processes, and fluxes, especially when combined with GHG driving force measurements. Nevertheless, with respect to the micrometeorological method, it causes a minimal but still unavoidable soil disturbance, and allows a minor temporal resolution. Several phases are key to the method implementation: i) chamber design and deployment, ii) sample handling and analyses, and iii) flux estimation. Technique implementation success in paddy fields demands adjustments for field flooding during much of the cropping cycle, and for rice plant maintenance within the chamber headspace during measurements. Therefore, the additional elements to be considered with respect to the usual application of non-flooded agricultural soils consist of devices for: i) avoiding any unintended water disturbance that could overestimate fluxes, and ii) including rice plants within the chamber headspace to fully consider gases emitted through aerenchyma transportation.

Assessment of Methane and Nitrous Oxide Fluxes from Paddy Field by Means of Static Closed Chambers Maintaining Plants Within Headspace

This protocol describes the measurement of greenhouse gas (GHG) emissions from paddy soils using the static closed chamber technique. This method is based on the diffusion theory. A known volume of air overlaying a defined soil area is enclosed within a parallelepiped cover (named "chamber"), for a defined period of time. During this enclosure period, gases (methane (CH4) and nitrous oxide (N2O)) move from soil pore air near their microbial source (i.e., methanogens, nitrifiers, denitrifiers) to the chamber headspace, following a natural concentration gradient. Fluxes are then estimated from chamber headspace concentration variations sampled at regular intervals throughout the enclosure and then analyzed with gas chromatography. Among the techniques available for GHG measurement, the static closed chamber method is suitable for plot experiments, as it does not require large homogenously treated soil areas. Furthermore, it is manageable with limited resources and can identify relationships among ecosystem properties, processes, and fluxes, especially when combined with GHG driving force measurements. Nevertheless, with respect to the micrometeorological method, it causes a minimal but still unavoidable soil disturbance, and allows a minor temporal resolution. Several phases are key to the method implementation: i) chamber design and deployment, ii) sample handling and analyses, and iii) flux estimation. Technique implementation success in paddy fields demands adjustments for field flooding during much of the cropping cycle, and for rice plant maintenance within the chamber headspace during measurements. Therefore, the additional elements to be considered with respect to the usual application of non-flooded agricultural soils consist of devices for: i) avoiding any unintended water disturbance that could overestimate fluxes, and ii) including rice plants within the chamber headspace to fully consider gases emitted through aerenchyma transportation.

Comparison between a Photo-Acoustic Analyzer System (PAS) and Gas Chromatograph (GC) for Measuring CO2 and N2O Emissions in a Corn/Soybean Field

There is a need to compare greenhouse gases (GHGs) measurements methods for data harmonization. The objective of this study was to compare Gas Chromatography (GC) and a Photo-Acoustic Analyzer System (PAS) as methods for measuring carbon dioxide (CO2) and nitrous oxide (N2O) emissions in a corn/soybean field. The study was conducted on a Waldron silt loam soil at Freeman farm of Lincoln University of Missouri. Sixteen cylindrical polyvinylchloride static chambers measuring 0.30 m in height and 0.20 m in diameter were permanently inserted into the soil to a depth of 0.05 m for GHGs measurements. Soil air samples were collected in each chamber with a 60 ml syringe and stored in a Tedlar bag for CO2 and N2O analysis by GC within 2 hours of sampling. CO2 and N2O measurements with PAS were done directly in-situ. Significant, stronger and positive correlations were found between PAS and GC in 11 out of 15 months - measurement cycles for CO2. The most significant correlation was observed in April 2015 (r = 0.90, p = 0.0001). For N2O, however, only 5 out of 15 measurements between PAS and GC had positive, but weak correlations. The highest correlation between PAS and GC measurements for N2O was also found in April 2015 (r = 0.71, p = 0.0020). Continuous monitoring of GHGs emissions is necessary to better understand their dynamics and how they are exacerbated by agricultural management practices. However, accurate measurement techniques are also needed.

Big data cloud computing framework for low carbon supplier selection in the beef supply chain

Purpose– With the rapid economic development of nations across the globe, there is proportionate increment in corresponding carbon footprint. There are numerous counter measures proposed to mitigate it in terms of legislation and policy framing. However, they have a shortsighted vision of predominantly focusing on manufacturing and transportation industry thereby neglecting one of the significant contributor of global emissions- agricultural industry. Among all the agri-food products, beef has the highest carbon footprint and majority of its emission are generated in beef farms. The issue is more intensive in developing nations where most of global cattle are raised and simultaneously farmers are less informed and aware of resources/technology to address emissions from their farms. Therefore, there is need to raise awareness among farmers and thereby incorporate carbon footprint as a major cattle supplier selection attribute by abattoir and processor and integrate it as a standard practice in procurement of cattle. Design/methodologyA novel framework based on big data cloud computing technology is developed for eco-friendly cattle supplier selection. It is capable of measuring greenhouse gas emissions in farms and assimilate into the cattle supplier selection process. Fuzzy AHP, DEMATEL and TOPSIS method is employed to make an optimum tradeoff between conventional quality attributes and carbon footprint generated in farms to select the most appropriate supplier. FindingsThe proposed framework would assist in shedding the environmental burden of beef supply chain as the majority of carbon footprint is generated in beef farms. Moreover, the vertical coordination in the supply chain among farmers and abattoir, processor would be strengthened. The execution of the framework is depicted in case study section. OriginalityThe literature is deficient of ecofriendly supplier selection in the agri-food sector particularly in developing countries. This study bridges the gap in the literature by proposing a novel framework to incorporate carbon footprint into traditional supplier selection process via an amalgamation of big data, ICT and Operations Research. The proposed framework would assist in mitigating the carbon footprint of beef products as they have highest emissions among all agri-food products. This framework is generic in nature and can be implemented in any food supply chain.

Measuring greenhouse gas emissions from international air travel of a country’s residents methodological development and application for Sweden

Global civil aviation accounts for 4–5% of total greenhouse gas emissions and these emissions are increasing. In the absence of sufficiently effective global climate instruments, national instruments might be considered as a complement, in which case some way of allocating emissions from international air travel between countries is needed. The purpose of this paper is to develop an accounting method that reflects one country's greenhouse gas emissions from international air travel, and to apply this methodology to Sweden. The new methodology consists of three parts: the number of international air trips made by the country's residents; the average distance of these trips; and the greenhouse gas emissions per passenger km. For Sweden, data for 1990 to 2014 show an increase in the number of trips by Sweden's population of 3.6% per year, resulting in, on average, one international journey (round trip 5800 km) per capita in 2014. The average distance to the final destination has increased only marginally due to simultaneous growth in both long and short trips. However, global average greenhouse gas emissions per passenger km have decreased by 1.9% per year between 1990 and 2014. Because the increase in the number of their trips has outweighed the decrease in emissions per km, the total emissions from Swedish residents' international air travel have increased by 61% between 1990 and 2014. The total emissions from Swedish residents' air travel, including both CO2 and non-CO2-effects, were 11 Mt CO2 equivalents in 2014, which is the same level as the emissions from Swedish car traffic. This type of reliable data is important when designing policies and for getting public support for new policies.

A review on air emissions assessment: Transportation

Abstract The greenhouse gas emissions footprint and global warming potential are widely-used for environmental sustainability studies. However, environmental sustainability is far wider than carbon emissions and climate change. This review aims to highlight the importance of considering air pollutants in optimisation studies and evaluate the limitation of the current assessments for air emissions, particularly in relation to transportation. The source of air pollutants is firstly overviewed with special attention on non-stationary sources, freight and sea transportation. The type of measurement to obtain the emission data and the available optimisation models on transport mode choice selection were then summarised. The strengths and Weaknesses' have been indicated. The identified gap includes greenhouse gas and air pollutants not being evaluated simultaneously and the interaction between the different pollutants are not being adequately considered. A better assessment framework and impact categories classification are consequently required. The summarised assessment model of transportation mode choice shows that the current viewpoint on low emissions, green or environmental sustainability options refers to carbon dioxide as a part of greenhouse gas. Attention towards a better emission assessment and management has been supported in this study through critical discussion. The next step of this work is to develop a methodology to measure greenhouse gas and air pollutants simultaneously by considering the synergistic effect and the discussed limitation. It is important for minimising the potential of footprint shifting and poor decision-making.

Reviews and syntheses: Anthropogenic perturbations to carbon fluxes in Asian river systems – concepts, emerging trends, and research challenges

Abstract. Human activities are drastically altering water and material flows in river systems across Asia. These anthropogenic perturbations have rarely been linked to the carbon (C) fluxes of Asian rivers that may account for up to 40–50 % of the global fluxes. This review aims to provide a conceptual framework for assessing the human impacts on Asian river C fluxes, along with an update on anthropogenic alterations of riverine C fluxes. Drawing on case studies conducted in three selected rivers (the Ganges, Mekong, and Yellow River) and other major Asian rivers, the review focuses on the impacts of river impoundment and pollution on CO2 outgassing from the rivers draining South, Southeast, and East Asian regions that account for the largest fraction of river discharge and C exports from Asia and Oceania. A critical examination of major conceptual models of riverine processes against observed trends suggests that to better understand altered metabolisms and C fluxes in “anthropogenic land-water-scapes”, or riverine landscapes modified by human activities, the traditional view of the river continuum should be complemented with concepts addressing spatial and temporal discontinuities created by human activities, such as river impoundment and pollution. Recent booms in dam construction on many large Asian rivers pose a host of environmental problems, including increased retention of sediment and associated C. A small number of studies that measured greenhouse gas (GHG) emissions in dammed Asian rivers have reported contrasting impoundment effects: decreased GHG emissions from eutrophic reservoirs with enhanced primary production vs. increased emissions from the flooded vegetation and soils in the early years following dam construction or from the impounded reaches and downstream estuaries during the monsoon period. These contrasting results suggest that the rates of metabolic processes in the impounded and downstream reaches can vary greatly longitudinally over time as a combined result of diel shifts in the balance between autotrophy and heterotrophy, seasonal fluctuations between dry and monsoon periods, and a long-term change from a leaky post-construction phase to a gradual C sink. The rapid pace of urbanization across southern and eastern Asian regions has dramatically increased municipal water withdrawal, generating annually 120 km3 of wastewater in 24 countries, which comprises 39 % of the global municipal wastewater production. Although municipal wastewater constitutes only 1 % of the renewable surface water, it can disproportionately affect the receiving river water, particularly downstream of rapidly expanding metropolitan areas, resulting in eutrophication, increases in the amount and lability of organic C, and pulse emissions of CO2 and other GHGs. In rivers draining highly populated metropolitan areas, lower reaches and tributaries, which are often plagued by frequent algal blooms and pulsatile CO2 emissions from urban tributaries delivering high loads of wastewater, tended to exhibit higher levels of organic C and the partial pressure of CO2 (pCO2) than less impacted upstream reaches and eutrophic impounded reaches. More field measurements of pCO2, together with accurate flux calculations based on river-specific model parameters, are required to provide more accurate estimates of GHG emissions from the Asian rivers that are now underrepresented in the global C budgets. The new conceptual framework incorporating discontinuities created by impoundment and pollution into the river continuum needs to be tested with more field measurements of riverine metabolisms and CO2 dynamics across variously affected reaches to better constrain altered fluxes of organic C and CO2 resulting from changes in the balance between autotrophy and heterotrophy in increasingly human-modified river systems across Asia and other continents.

A UAV-based active AirCore system for measurements of greenhouse gases

Abstract. We developed and field-tested an unmanned aerial vehicle (UAV)-based active AirCore for atmospheric mole fraction measurements of CO2, CH4, and CO. The system applies an alternative way of using the AirCore technique invented by NOAA. As opposed to the conventional concept of passively sampling air using the atmospheric pressure gradient during descent, the active AirCore collects atmospheric air samples using a pump to pull the air through the tube during flight, which opens up the possibility to spatially sample atmospheric air. The active AirCore system used for this study weighs ∼ 1.1 kg. It consists of a ∼ 50 m long stainless-steel tube, a small stainless-steel tube filled with magnesium perchlorate, a KNF micropump, and a 45 µm orifice working together to form a critical flow of dried atmospheric air through the active AirCore. A cavity ring-down spectrometer (CRDS) was used to analyze the air samples on site not more than 7 min after landing for mole fraction measurements of CO2, CH4, and CO. We flew the active AirCore system on a UAV near the atmospheric measurement station at Lutjewad, located in the northwest of the city of Groningen in the Netherlands. Five consecutive flights took place over a 5 h period on the same morning, from sunrise until noon. We validated the measurements of CO2 and CH4 from the active AirCore against those from the Lutjewad station at 60 m. The results show a good agreement between the measurements from the active AirCore and the atmospheric station (N = 146; RCO22: 0.97 and RCH42: 0.94; and mean differences: ΔCO2: 0.18 ppm and ΔCH4: 5.13 ppb). The vertical and horizontal resolution (for CH4) at typical UAV speeds of 1.5 and 2.5 m s−1 were determined to be ±24.7 to 29.3 and ±41.2 to 48.9 m, respectively, depending on the storage time. The collapse of the nocturnal boundary layer and the buildup of the mixed layer were clearly observed with three consecutive vertical profile measurements in the early morning hours. Besides this, we furthermore detected a CH4 hotspot in the coastal wetlands from a horizontal flight north to the dike, which demonstrates the potential of this new active AirCore method to measure at locations where other techniques have no practical access.

Carbon Footprint Measurement and Management: Case Study of the School Forest Enterprise

This paper applies a corporate accounting standard approach for measuring greenhouse gas emissions for a particular entity, the GHG Protocol, for a specific type of company in the primary sector. The main goal was to measure the total carbon footprint and carbon balance of the School Forest Enterprise of the Czech University of Life Sciences Prague. The total carbon footprint for Scope 1, Scope 2, and Scope 3 of the forestland managed by the SFE in 2017 was 686 t CO2-eq or 3.5 t/employee, and 3.8 CZK/1000 CZK of turnover or 99 kg CO2-eq/ha. These findings suggested a specific role of forest management in terms of climate change, where, in contrast with other companies in the secondary and tertiary spheres, the sinks outweigh the greenhouse gas production.

Drought drives rapid shifts in tropical rainforest soil biogeochemistry and greenhouse gas emissions

Climate change models predict more frequent and severe droughts in the humid tropics. How drought will impact tropical forest carbon and greenhouse gas dynamics is poorly understood. Here we report the effects of the severe 2015 Caribbean drought on soil moisture, oxygen, phosphorus (P), and greenhouse gas emissions in a humid tropical forest in Puerto Rico. Drought significantly decreases inorganic P concentrations, an element commonly limiting to net primary productivity in tropical forests, and significantly increases organic P. High-frequency greenhouse gas measurements show varied impacts across topography. Soil carbon dioxide emissions increase by 60% on slopes and 163% in valleys. Methane (CH4) consumption increases significantly during drought, but high CH4 fluxes post-drought offset this sink after 7 weeks. The rapid response and slow recovery to drought suggest tropical forest biogeochemistry is more sensitive to climate change than previously believed, with potentially large direct and indirect consequences for regional and global carbon cycles.

Long open-path measurements of greenhouse gases in air using near-infrared Fourier transform spectroscopy

Abstract. In complex and urban environments, atmospheric trace gas composition is highly variable in time and space. Point measurement techniques for trace gases with in situ instruments are well established and accurate, but do not provide spatial averaging to compare against developing high-resolution atmospheric models of composition and meteorology with resolutions of the order of a kilometre. Open-path measurement techniques provide path average concentrations and spatial averaging which, if sufficiently accurate, may be better suited to assessment and interpretation with such models. Open-path Fourier transform spectroscopy (FTS) in the mid-infrared region, and differential optical absorption spectroscopy (DOAS) in the UV and visible, have been used for many years for open-path spectroscopic measurements of selected species in both clean air and in polluted environments. Near infrared instrumentation allows measurements over longer paths than mid-infrared FTS for species such as greenhouse gases which are not easily accessible to DOAS.In this pilot study we present the first open-path near-infrared (4000–10 000 cm−1, 1.0–2.5 µm) FTS measurements of CO2, CH4, O2, H2O and HDO over a 1.5 km path in urban Heidelberg, Germany. We describe the construction of the open-path FTS system, the analysis of the collected spectra, several measures of precision and accuracy of the measurements, and the results a four-month trial measurement period in July–November 2014. The open-path measurements are compared to calibrated in situ measurements made at one end of the open path. We observe significant differences of the order of a few ppm for CO2 and a few tens of ppb for CH4 between the open-path and point measurements which are 2 to 4 times the measurement repeatability, but we cannot unequivocally assign the differences to specific local sources or sinks. We conclude that open-path FTS may provide a valuable new tool for investigations of atmospheric trace gas composition in complex, small-scale environments such as cities.

Greenhouse gas measurements from a UK network of tall towers: technical description and first results

Abstract. A network of three tall tower measurement stations was set up in 2012 across the United Kingdom to expand measurements made at the long-term background northern hemispheric site, Mace Head, Ireland. Reliable and precise in situ greenhouse gas (GHG) analysis systems were developed and deployed at three sites in the UK with automated instrumentation measuring a suite of GHGs. The UK Deriving Emissions linked to Climate Change (UK DECC) network uses tall (165–230 m) open-lattice telecommunications towers, which provide a convenient platform for boundary layer trace gas sampling. In this paper we describe the automated measurement system and first results from the UK DECC network for CO2, CH4, N2O, SF6, CO and H2. CO2 and CH4 are measured at all of the UK DECC sites by cavity ring-down spectroscopy (CRDS) with multiple inlet heights at two of the three tall tower sites to assess for boundary layer stratification. The short-term precisions (1σ on 1 min means) of CRDS measurements at background mole fractions for January 2012 to September 2015 is &lt; 0.05 µmol mol−1 for CO2 and &lt; 0.3 nmol mol−1 for CH4. Repeatability of standard injections (1σ) is &lt; 0.03 µmol mol−1 for CO2 and &lt; 0.3 nmol mol−1 for CH4 for the same time period. N2O and SF6 are measured at three of the sites, and CO and H2 measurements are made at two of the sites, from a single inlet height using gas chromatography (GC) with an electron capture detector (ECD), flame ionisation detector (FID) or reduction gas analyser (RGA). Repeatability of individual injections (1σ) on GC and RGA instruments between January 2012 and September 2015 for CH4, N2O, SF6, CO and H2 measurements were &lt; 2.8 nmol mol−1, &lt; 0.4 nmol mol−1, &lt; 0.07 pmol mol−1, &lt; 2 nmol mol−1 and &lt; 3 nmol mol−1, respectively. Instrumentation in the network is fully automated and includes sensors for measuring a variety of instrumental parameters such as flow, pressures, and sampling temperatures. Automated alerts are generated and emailed to site operators when instrumental parameters are not within defined set ranges. Automated instrument shutdowns occur for critical errors such as carrier gas flow rate deviations. Results from the network give good spatial and temporal coverage of atmospheric mixing ratios within the UK since early 2012. Results also show that all measured GHGs are increasing in mole fraction over the selected reporting period and, except for SF6, exhibit a seasonal trend. CO2 and CH4 also show strong diurnal cycles, with night-time maxima and daytime minima in mole fractions.