scholarly journals Mercury flux measurements in a naturally enriched area: Correlation with environmental conditions during the Nevada Study and Tests of the Release of Mercury From Soils (STORMS)

1999 ◽  
Vol 104 (D17) ◽  
pp. 21845-21857 ◽  
Author(s):  
Laurier Poissant ◽  
Martin Pilote ◽  
Alain Casimir
Keyword(s):  
Environmental Conditions ◽  
Flux Measurements ◽  
Mercury Flux

Sources of variability in mercury flux measurements

2001 ◽  
Vol 106 (D6) ◽  
pp. 5421-5435 ◽  
Author(s):  
G. C. Edwards ◽  
P. E. Rasmussen ◽  
W. H. Schroeder ◽  
R. J. Kemp ◽  
G. M. Dias ◽  
...  
Keyword(s):  
Flux Measurements ◽  
Mercury Flux

Spatial soil respiration measurements under varying environmental conditions in a dry grassland

2020 ◽  
Author(s):  
János Balogh ◽  
Szilvia Fóti ◽  
Bernadett Gecse ◽  
Marianna Papp ◽  
Gabriella Süle ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Spatial Variability ◽  
Environmental Conditions ◽  
Summer Drought ◽  
Dry Grassland ◽  
Greenhouse Gas Flux ◽  
Major Disadvantage ◽  
Flux Measurements ◽  
Eddy Covariance Measurements ◽  
Footprint Area

<p>Spatial variability of ecosystem processes constitutes significant uncertainty source in greenhouse gas flux measurements and estimations. The major disadvantage of the chamber-based flux measurements is the poor spatial representativeness, but eddy-covariance measurements also have an uncertainty due to the unequal and not constant footprint area. One way to overcome these difficulties is the spatial sampling improving the field-scale data coverage.</p><p>The aim of this study was to describe the spatial variability of grassland soil CO<sub>2</sub> efflux under varying environmental conditions. For this reason, we conducted spatial measurements on a range of variables including soil respiration, above-ground biomass, greenness index of the vegetation, soil water content and soil temperature during a seven-year study in a dry grassland site in Hungary. Altitude and soil organic carbon (SOC) content of the measuring positions were also used as background factors. Measurements were repeated 19 times at 78 positions during the study, in the main phenological stages of the grassland vegetation: spring growth, summer drought, autumn regrowth. The sampling scheme was based on 80×60 m grid of 10 m resolution. SOC content was highly variable among the positions due to the exposure differences and their environmental constrains. We analyzed the effect of the drivers on soil respiration grouping the measuring positions by the SOC content of the soil.</p>

Low-cost methane (CH4) sensors for use in in flux chambers

2020 ◽  
Author(s):  
David Bastviken ◽  
Jonatan Nygren ◽  
Jonathan Schenk ◽  
Roser Parrelada Massana ◽  
Nguyen Thanh Duc
Keyword(s):  
Greenhouse Gas ◽  
Environmental Conditions ◽  
Large Scale ◽  
Variable Temperature ◽  
Low Cost ◽  
Local Level ◽  
Limiting Factor ◽  
Gas Flux ◽  
Greenhouse Gas Flux ◽  
Flux Measurements

<p>The lack of reliable low-cost greenhouse gas flux measurement approaches limit our ability quantify regulation and verify mitigation efforts at the local level.   Methane (CH4), one of the most important greenhouse gases, is particularly dependent on local measurements because levels are regulated by a complex combination of sources, sinks and environmental conditions. There are still major gaps in the global methane budget and the reasons for the irregular development over time remains unclear. Facilitation of local flux measurements in all parts of the world therefore seem important to constrain large-scale assessments. As the high cost of gas analysers is a limiting factor for flux measurements, we here present how low-cost CH4 sensors can be used outside their specified range to yield reasonably accurate chamber-based flux measurements. By using a two-step calibration approach, testing multiple alternatives on how to model interference from temperature and humidity, an R2 ≥ 0.99 was achieved over a CH4 concentration range of 2 – 700 ppm under variable temperature and relative humidity. We also demonstrate ways to reach such calibration results without complicated calibration experiments and instead using in the order of 20 in situ reference measurements at different environmental conditions. Finally we, constructed and described a make-it-yourself Arduino based logger with the tested sensors for CH<sub>4</sub>, temperature, humidity and carbon dioxide (CO<sub>2</sub>) intended for flux chamber use with a material cost of approximately 200 Euro. We hope that this can contribute to more widespread greenhouse gas flux measurements in many environments and countries.</p>

scholarly journals Interannual variability of the ecosystem CO<sub>2</sub> fluxes at paludified spruce forest and ombrotrophic bog in southern taiga

2021 ◽  
Author(s):  
Vadim Mamkin ◽  
Vitaly Avilov ◽  
Dmitry Ivanov ◽  
Andrey Varlagin ◽  
Julia Kurbatova
Keyword(s):  
Interannual Variability ◽  
Environmental Conditions ◽  
Ecosystem Respiration ◽  
Growing Season ◽  
Southern Taiga ◽  
Co2 Uptake ◽  
Forest Site ◽  
Spruce Forest ◽  
Ombrotrophic Bog ◽  
Flux Measurements

Abstract. Climate warming in high latitudes impacts CO2 sequestration of northern peatlands through the changes in both production and decomposition processes. The response of the net CO2 fluxes between ecosystems and the atmosphere to the climate change and weather anomalies can vary across the forest and non-forest peatlands. To better understand the differences in CO2 dynamics at forest and non-forest boreal peatlands induced by changes in environmental conditions the estimates of interannual variability of the net ecosystem exchange (NEE), total ecosystem respiration (TER) and gross primary production (GPP) was obtained at two widespread peatland ecosystems – paludified spruce forest and adjacent ombrotrophic bog in the southern taiga of west Russia using 6-year of paired eddy covariance flux measurements. The period of measurements (2015–2020) was characterized by both positive and negative annual and growing season air temperature and precipitation anomalies. Flux measurements showed that in spite of the lower growing season TER (332…339 gC∙m−2) and GPP (442…464 gC∙m−2) rates the bog had a lower NEE (−132…−108) than the forest excepting the warmest and the wettest year of the period and was a sink of atmospheric CO2 in the selected years while the forest was a CO2 sink or source between years depending on the environmental conditions. Growing season NEE at the forest site was between −142 and 28 gC∙m−2, TER between 1135 and 1366 gC∙m−2 and GPP between 1207 and 1462 gC∙m−2. Annual NEE at the forest was between −62 and 145 gC∙m−2, TER between 1429 and 1652 gC∙m−2 and GPP between 1345 and 1566 gC∙m−2 respectively. Anomalously warm winter with sparse and thin snow cover lead to the increased GPP as well as lower NEE in early spring at forest and to the increased spring TER at the bog. Also, the shifting of the compensation point to the earlier dates at the forest and to the later dates at the bog following the warmest winter of the period was detected. This study suggest that the warming in winter can increase CO2 uptake of the paludified spruce forests of southern taiga in non-growing season.

Vibration Isolator System for Electron Microscope

1990 ◽  
Vol 48 (1) ◽  
pp. 182-183
Author(s):  
K. Ohi ◽  
M. Mizuno ◽  
T. Kasai ◽  
Y. Ohkura ◽  
K. Mizuno ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Magnetic Fields ◽  
Environmental Conditions ◽  
Vibration Isolator ◽  
Air Conditioners ◽  
Vibration Isolators ◽  
Large Size ◽  
Electron Microscopes

In recent years, with electron microscopes coming into wider use, their installation environments do not necessarily give their performance full play. Their environmental conditions include air-conditioners, magnetic fields, and vibrations. We report a jointly developed entirely new vibration isolator which is effective against the vibrations transmitted from the floor.Conventionally, large-sized vibration isolators which need the digging of a pit have been used. These vibration isolators, however, are large present problems of installation and maintenance because of their large-size.Thus, we intended to make a vibration isolator which1) eliminates the need for changing the installation room2) eliminates the need of maintenance and3) are compact in size and easily installable.

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