Assessment of Ventilation Efficiency in School Classrooms Based on Indoor–Outdoor Particulate Matter and Carbon Dioxide Measurements

The concentration of indoor suspended particulate matter is considered to be one of the main factors that affect health and quality of life. In Poland, in response to the pressure of public opinion, a few thousand air purifiers have been installed in public buildings where children spend time. However, another factor that also impacts upon the quality of indoor air, namely increased CO2 mixing ratios, is frequently overlooked. The only way to remove CO2 excess from interiors is through intensive ventilation. This is often an action at odds with the need to maintain low concentrations of particulate matter in indoor air. Two methods are presented to assess the rate of air exchange using CO2 or particulate matter as a tracer. One of the methods using indoor/outdoor PM (particulate matter) concentrations is based on the use of box models for analysis. The second one uses indoor CO2 concentration change analysis. At the tested locations, they showed large deviations of the determined values of the air exchange coefficients from its limits. Both methods showed consistent ventilation parameters estimation.

Humic Carbon to Fix Food, Climate and Health

Shutdown for just six days enables land plants to entirely fix CO2 excess of +4 Gt C per yr. Rebuilding soil organic carbon (SOC) in worm-worked humus is the only practical carbon capture and storage (CCS) capable of freely offsetting annual anthropogenic emissions. A case is made to redirect all available resources towards proven, earthworm-based, organic husbandry. Priority is to safely combat mounting global threats due to irreversible species extinction, perilous climate change and deteriorating human wellbeing (mental/physical health). All three interlinked risks are underpinned by a relentless, yet largely ignored, critical loss of precious topsoil. A first step to topsoil recovery is vermi-composting all vegetable and animal ‘wastes’ for return to the field.

Temporal Variation of Atmospheric Fossil and Modern CO2 Excess at a Central European Rural Tower Station between 2008 and 2014

In 2008, the atmospheric CO2 measurements at the Hegyhátsál rural tower station were extended further by 14CO2 air sampling from two elevations (115 and 10 m a.g.l.), in cooperation with HEKAL (ICER). Since then, a complete six-year-long (2008–2014) dataset of atmospheric CO2, Δ14C, fossil, and modern CO2 excess (relative to Jungfraujoch) has been assembled and evaluated. Based on our results, the annual mean CO2 mole fraction rose at both elevations in this period. The annual mean Δ14CO2 values decreased with a similar average annual decline. Based on our comparison, planetary boundary layer height obtained by modeling has a larger influence on the variation of mole fraction of CO2 (relative to Jungfraujoch), than on its carbon isotopic composition, i.e. the boundary layer rather represents a physical constraint. Fossil fuel CO2 excess at both elevations can rather be observed in wintertime and mainly due to the increased anthropogenic emission of nearby cities in the region. The mean modern CO2 excess at both elevations was even larger in winter, but it drastically decreased at 115 m by summer, while it remained at the winter level at 10 m.

Detection and variability of combustion-derived vapor in an urban basin

Water emitted during combustion may comprise a significant portion of ambient humidity (> 10 %) in urban areas, where combustion emissions are strongly focused in space and time. Stable water vapor isotopes can be used to apportion measured humidity values between atmospherically transported and combustion-derived water vapor, as combustion vapor possesses an unusually negative deuterium excess value (d-excess, d = δ2H − 8δ18O). We investigated the relationship between d-excess of atmospheric vapor, ambient CO2 concentrations, and atmospheric stability across four winters in Salt Lake City, UT. We found a robust inverse relationship between CO2 excess above background and d-excess on sub-diurnal to seasonal timescales, which was most prominent during periods of strong atmospheric stability that occur during Salt Lake City winter. We developed a framework for partitioning changes in water vapor d-excess between advective changes in vapor and the addition of combustion derived vapor. Using a Keeling-style mixing model approach, we estimated the d-excess of combustion derived vapor in Salt Lake City to be between −125 ‰ and −308 ‰, broadly consistent with theoretical estimates. Moreover, our analysis highlights that changes in the observed d-excess during periods of high atmospheric stability cannot be explained without a vapor source possessing a strongly negative d-excess value. Further refinements in our estimate of the isotopic composition of combustion derived vapor require constraints on valley-scale stoichiometry between CO2 and H2O in combustion products, yet our results demonstrate the utility of stable water vapor isotopes to constrain contributions of combustion to urban humidity and meteorology.

Spatial and temporal variations of dissolved organic carbon and inorganic carbon concentrations and δ¹³C in a peatland-stream continuum: implications of peatland invasion by vascular plants

Dissolved fluxes of C which are an important component of the global C budget of peatlands may be affected by global change in different ways. The evolution of peatland vegetation is an issue caused by the indirect effect of global change that still needs to be addressed. The aim of this study was to study the temporal and spatial variations in the quantity and the characteristics of dissolved C within in a peatland stream continuum, the peatland being invaded by Molinia caerulea and Betula spp. The study highlighted the following key points: (i) Vegetation change tends to increase the DOC concentration of peat surface water. (ii) DOC exports were in the range of those found in the literature, and it was clearly established that peatland DOC can reach second order streams. (iii) Peat water was supersaturated in CO2 especially in summer during the peak of microbial activity. (iv) the CO2 critical layer at the surface of the soil may promote CO2 excess build-up in the peat water. This critical layer may promote CO2 export out of the peatland. The effect of vegetation change on the DOC content of peat water deserves further attention as it may have a deep impact on downstream river water quality. In particular, it is necessary to clarify whether the concentration of C dynamics is affected by the invading species. More attention should be paid to hydrological processes (e.g. pumping capacity of the different plants) and the microbial activity in the rhizosphere of the invading plants. Also, the relation between the CO2 critical zone at the surface of the soil and the CO2 concentration in water should be studied in detail.