A world model of soil carbon dioxide

Brook, George A.; Folkoff, Michael E.; Box, Elgene O.

doi:10.1002/esp.3290080108

Cited by 251 publications

(154 citation statements)

References 29 publications

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“…(Wigley and Brown, 1976) we can use the values from Isverna and Ascunsȃ caves to calculate a local lapse rate that should be taken into account when discussing the altitude effect on δ 18 O. Given a 2.8 • C difference between Isverna and Ascunsȃ (POM 2) for the relatively stable period of 2015-2016, we calculated a value of 6.1 • C km −1 , in agreement with the global value of 6.4 • C km −1 (Brunt, 1933).…”

Section: Temperature Regime Of Ascunsȃ and Isverna Cavessupporting

confidence: 60%

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Transfer of environmental signals from the surface to the underground at Ascunsă Cave, Romania

Drăguşin

Balan

Blamart

et al. 2017

Hydrol. Earth Syst. Sci.

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Abstract. We present here the results of a 4-year environmental monitoring program at Ascunsȃ Cave (southwestern Romania) designed to help us understand how climate information is transferred through the karst system and archived by speleothems. The air temperature inside the cave is around 7 • C, with slight differences between the upper and lower parts of the main passage. CO 2 concentrations in cave air have a seasonal signal, with summer minima and winter maxima. These might indicate the existence of an organic matter reservoir deep within the epikarst that continues to decompose over the winter, and CO 2 concentrations are possibly modulated by seasonal differences in cave ventilation.The maximum values of CO 2 show a rise after the summer of 2014, from around 2000 to about 3500 ppm, following a rise in surface temperature. Using two newly designed types of water-air equilibrators, we were able to determine the concentration of CO 2 dissolved in drip water by measuring its concentration in the equilibrator headspace and then using Henry's law to calculate its concentration in water. This method opens the possibility of continuous data logging using infrared technology, without the need for costly and less reliable chemical determinations. The local meteoric water line (δ 2 H = 7.7 δ 18 O + 10.1), constructed using monthly aggregated rainfall samples, is similar to the global one, revealing the Atlantic as the strongly dominant vapor source. The deuterium excess values, as high as 17 ‰, indicate that precipitation has an important evaporative component, possibly given by moisture recycling over the European continent. The variability of stable isotopes in drip water is similar at all points inside the cave, suggesting that the monitored drip sites are draining a homogenous reservoir. Drip rates, as well as stable isotopes, indicate that the transfer time of water from the surface is on the order of a few days.

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Section: Temperature Regime Of Ascunsȃ and Isverna Cavessupporting

confidence: 60%

“…son, 1977, and references therein; Brook et al, 1983), and shows a similar profile to CO 2atm . Supported by the resemblance between CO 2atm and CO 2ca at POM A, we can state that the change in equilibrator type at POM A in November 2015 did not seem to affect the measured values of CO 2ca .…”

Section: Co 2 Concentration In Cave Air and Drip Watermentioning

confidence: 67%

Transfer of environmental signals from the surface to the underground at Ascunsă Cave, Romania

Drăguşin

Balan

Blamart

et al. 2017

Hydrol. Earth Syst. Sci.

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“…Carbonate speleothems arise primarily because of the creation of supersaturated waters by CO 2 -degassing (Holland et al, 1964) and the extent of speleothem growth relates to the difference between soil PCO 2 , higher in warmer, moist climates (Brook et al, 1983) and cave air PCO 2 . There has been a relative neglect of the process of air circulation in caves an essential part of their physiology (Carrasco et al, 1995;Fairchild et al, in press a), which allows CO 2 to be removed and hence CaCO 3 to be precipitated.…”

Section: Cave Airmentioning

confidence: 99%

Modification and preservation of environmental signals in speleothems

Fairchild

Smith

Baker

et al. 2006

Earth-Science Reviews

732

506

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Speleothems are primarily studied in order to generate archives of climatic change and results have led to significant advances in identifying and dating major shifts in the climate system. However, the climatological meaning of many speleothem records cannot be interpreted unequivocally; this is particularly so for more subtle shifts and shorter time periods, but the use of multiple proxies and improving understanding of formation mechanisms offers a clear way forward.An explicit description of speleothem records as time series draws attention to the nature and importance of the signal filtering processes by which the weather, the seasons and longer-term climatic and other environmental fluctuations become encoded in speleothems. We distinguish five sources of variation that influence speleothem geochemistry: atmospheric, vegetation/soil, karstic aquifer, primary speleothem crystal growth and secondary alteration and give specific examples of their influence. The direct role of climate diminishes progressively through these five factors.We identify and review a number of processes identified in recent and current work that bear significantly on the conventional interpretation of speleothem records, for example: 1) speleothem geochemistry can vary seasonally and hence a research need is to establish the proportion of growth attributable to different seasons and whether this varies over time.2) whereas there has traditionally been a focus on monthly mean δ 18 O data of atmospheric moisture, current work emphasizes the importance of understanding the synoptic processes that lead to characteristic isotope signals, since changing relative abundance of different weather types might 1 Corresponding author, fax +44(0)1214145528, E-mail: i.j.fairchild@bham.ac.uk control their variation on the longer-term. 3) the ecosystem and soil zone overlying the cave fundamentally imprint the carbon and trace element signals and can show characteristic variations with time. 4) new modelling on aquifer plumbing allows quantification of the effects of aquifer mixing. 5) recent work has emphasized the importance and seasonal variability of CO 2 -degassing leading to calcite precipitation upflow of a depositional site on carbon isotope and trace element composition of speleothems. 6) Although much is known about the chemical partitioning between water and stalagmites, variability in relation to crystal growth mechanisms and kinetics is a research frontier. 7) Aragonite is susceptible to conversion to calcite with major loss of chemical information, but the controls on the rate of this process are obscure.Analytical factors are critical to generate high-resolution speleothem records. A variety of methods of trace element analysis are available, but standardization is a common problem with the most rapid methods. New stable isotope data on Irish stalagmite CC3 compares rapid laser-ablation techniques with the conventional analysis of micromilled powders and ion microprobe methods. A high degree of comparability between techniques ...

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“…), and may reach 10 -1.5 atm. under extreme conditions (Reardon et al, 1979;Brook et al, 1983). Rapid gas exchange, and thus non-extreme conditions, probably occurred in the seeded pots since relatively rapid desiccation and crack formation were observed.…”

Section: Thermodynamic Stability Ofmentioning

confidence: 99%

The effect of phytostabilization on Zn speciation in a dredged contaminated sediment using scanning electron microscopy, X-ray fluorescence, EXAFS spectroscopy, and principal components analysis

Panfili

Manceau

Sarret

et al. 2005

Geochimica et Cosmochimica Acta

122

129

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Running Title: Effect of phytostabilzation on Zn speciation in dredged sediment 2 ABSTRACTThe maintenance of waterways generates large amounts of dredged sediments, which are deposited on adjacent land surfaces. These sediments are often rich in metal contaminants and present a risk to the local environment. Understanding how the metals are immobilized at the molecular level is critical for formulating effective metal containment strategies, such as phytoremediation. In the present work, the mineralogical transformations of Zn Seven Zn species were identified at the micrometer-scale : sphalerite, gahnite, franklinite, Zncontaining ferrihydrite and phosphate, (Zn-Al)-hydrotalcite, and Zn-substituted, kerolite-like, trioctahedral phyllosilicate. Bulk fractions of each species were quantified by LSF of the powder EXAFS spectra to linear combinations of the identified Zn species spectra.In the untreated and unvegetated sediment, Zn was distributed as ~50 % (mole ratio of total Zn) sphalerite, ~40 % Zn-ferrihydrite, and ~10-20 % (Zn-Al)-hydrotalcite plus Znphyllosilicate. In unvegetated but amended sediments (AP and TS), ZnS and Zn-ferrihydrite each decreased by 10 to 20 % and were replaced by Zn-phosphate (~30-40 %). In the presence of plants, ZnS was almost completely dissolved and the released Zn bound to phosphate (~40-60 %) and to Zn phyllosilicate plus (Zn,Al)-hydrotalcite (~20-40 %). Neither the plant species 3 nor the co-addition of mineral amendment affected the Zn speciation in the vegetated sediment.The sediment pore waters were supersaturated with respect to Zn-containing trioctahedral phyllosilicate, near-saturation with respect to Zn-phosphate, and strongly undersaturated with respect to (Zn,Al)-hydrotalcite. Therefore, the formation of (Zn,Al)-hydrotalcite in slightly alkaline conditions ought to result from heterogenous precipitation on mineral surface. 4

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A world model of soil carbon dioxide

Cited by 251 publications

References 29 publications

Transfer of environmental signals from the surface to the underground at Ascunsă Cave, Romania

Transfer of environmental signals from the surface to the underground at Ascunsă Cave, Romania

Modification and preservation of environmental signals in speleothems

The effect of phytostabilization on Zn speciation in a dredged contaminated sediment using scanning electron microscopy, X-ray fluorescence, EXAFS spectroscopy, and principal components analysis

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