The hydrogen and oxygen isotope geochemistry of pedogenic clay minerals: principles and theoretical background

Savin, Samuel M.; Hsieh, Jean C.C.

doi:10.1016/s0016-7061(97)00103-1

Cited by 90 publications

(43 citation statements)

References 59 publications

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“…Such an exchange would influence the adsorbed water but it would also influence the unconfined water, which is in equilibrium with the adsorbed water but could not influence the fractionation between them. The same would apply for an exchange between carbonate oxygen and water oxygen (Savin and Hsieh, 1998;Zeebe, 2009), although our samples did not contain any carbonate.…”

Section: Excluding Mechanisms Other Than the Proposed Surface Effectmentioning

confidence: 85%

2H and 18O depletion of water close to organic surfaces

Chen¹,

Auerswald²,

Schnyder³

2016

Biogeosciences

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Abstract. Hydrophilic surfaces influence the structure of water close to them and may thus affect the isotope composition of water. Such an effect should be relevant and detectable for materials with large surface areas and low water contents. The relationship between the volumetric solid : water ratio and the isotopic fractionation between adsorbed water and unconfined water was investigated for the materials silage, hay, organic soil (litter), filter paper, cotton, casein and flour. Each of these materials was equilibrated via the gas phase with unconfined water of known isotopic composition to quantify the isotopic difference between adsorbed water and unconfined water. Across all materials, isotopic fractionation was significant (p<0.05) and negative (on average −0.91 ± 0.22 ‰ for 18/16 O and −20.6 ± 2.4 ‰ for 2/1 H at an average solid : water ratio of 0.9). The observed isotopic fractionation was not caused by solutes, volatiles or old water because the fractionation did not disappear for washed or oven-dried silage, the isotopic fractionation was also found in filter paper and cotton, and the fractionation was independent of the isotopic composition of the unconfined water. Isotopic fractionation became linearly more negative with increasing volumetric solid : water ratio and even exceeded −4 ‰ for 18/16 O and −44 ‰ for 2/1 H. This fractionation behaviour could be modelled by assuming two water layers: a thin layer that is in direct contact and influenced by the surface of the solid and a second layer of varying thickness depending on the total moisture content that is in equilibrium with the surrounding vapour. When we applied the model to soil water under grassland, the soil water extracted from 7 and 20 cm depth was significantly closer to local meteoric water than without correction for the surface effect. This study has major implications for the interpretation of the isotopic composition of water extracted from organic matter, especially when the volumetric solid : water ratio is larger than 0.5 or for processes occurring at the solid-water interface.

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Section: Excluding Mechanisms Other Than the Proposed Surface Effectmentioning

confidence: 85%

2H and 18O depletion of water close to organic surfaces

Chen¹,

Auerswald²,

Schnyder³

2016

Biogeosciences

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“…In contrast to SOM, the isotopic composition of pedogenic clay minerals has been intensively studied since the beginning of the 1970s (Savin and Epstein, 1970;Lawrence and Taylor, 1971;Sheppard and Gilg 1996;Savin and Hsieh, 1998). The δ 2 H value of pedogenic clay minerals mainly depends on (1) the average δ 2 H value of soil water at the site and time of formation, and on (2) the size of the equilibrium isotopic fractionation factor between soil water and clay mineral at the temperature of formation (Savin and Epstein, 1970;Lawrence and Taylor, 1971;Sheppard and Gilg 1996;Savin and Hsieh, 1998). Lawrence (1970) and Lawrence and Taylor (1971) reported a correlation of δ 2 H values of pedogenic clay minerals with average annual δ 2 H values of precipitation at the corresponding sampling site.…”

Section: Introductionmentioning

confidence: 99%

Isotope ratios of nonexchangeable hydrogen in soils from different climate zones

2010

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“…In this sense it is very important to consider that surface temperature change may be coupled with elevation change and that this surface temperature change may modify the isotopic record produced by changing ␦ 18 O precipitation (Savin and Hsieh, 1998). As mineral-water fractionation factors depend upon absolute temperature and do not vary linearly with temperature, assessing the isotopic effect of changing mineral formation temperatures, in principle, requires a priori knowledge of absolute temperatures.…”

mentioning

confidence: 99%

Empirical relationships between elevation and the stable isotope composition of precipitation and surface waters: considerations for studies of paleoelevation change

Poage¹

2001

American Journal of Science

600

436

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ABSTRACT. A compilation of 68 studies from throughout many of the world's mountain belts reveals an empirically consistent and linear relationship between change in elevation and change in the isotopic composition of precipitation along altitudinal transects. The isotopic composition of precipitation decreases linearly with increasing elevation in most regions of the world except in the Himalayas and at elevations >5000 m. There are no significant differences in isotopic lapse rates from most regions of the world (ϳ0.28 permil/100 m) except at the extreme latitudes where isotopic lapse rates are higher. Given information on past changes in the isotopic composition of precipitation preserved in pedogenic or authigenic minerals, this global isotopic lapse rate can be used to place numerical constraints on the topographic development of some ancient mountain belts or plateaus.There are many complicating factors that can confound interpretation of paleoelevation change based on stable isotopes, and many of these are unique to specific mountain belts or time periods. Relevant to all stable isotope based paleoelevation change studies is the temperature dependent isotope fractionation between a pedogenic or authigenic mineral and the water from which it forms. In cases where isotopic proxy minerals are sampled from localities where temperature will change simultaneously with elevation change, the apparent change in the isotopic composition of precipitation may be dampened by several permil. This suggests that samples taken from the rainshadow side of an emerging orographic barrier may be more likely to preserve isotopic changes resulting from mountain uplift than samples taken from atop a rising mountain range or plateau.

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The hydrogen and oxygen isotope geochemistry of pedogenic clay minerals: principles and theoretical background

Cited by 90 publications

References 59 publications

<sup>2</sup>H and <sup>18</sup>O depletion of water close to organic surfaces

<sup>2</sup>H and <sup>18</sup>O depletion of water close to organic surfaces

Isotope ratios of nonexchangeable hydrogen in soils from different climate zones

Empirical relationships between elevation and the stable isotope composition of precipitation and surface waters: considerations for studies of paleoelevation change

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The hydrogen and oxygen isotope geochemistry of pedogenic clay minerals: principles and theoretical background

Cited by 90 publications

References 59 publications

&lt;sup&gt;2&lt;/sup&gt;H and &lt;sup&gt;18&lt;/sup&gt;O depletion of water close to organic surfaces

&lt;sup&gt;2&lt;/sup&gt;H and &lt;sup&gt;18&lt;/sup&gt;O depletion of water close to organic surfaces

Isotope ratios of nonexchangeable hydrogen in soils from different climate zones

Empirical relationships between elevation and the stable isotope composition of precipitation and surface waters: considerations for studies of paleoelevation change

Contact Info

Product

Resources

About

<sup>2</sup>H and <sup>18</sup>O depletion of water close to organic surfaces

<sup>2</sup>H and <sup>18</sup>O depletion of water close to organic surfaces