scholarly journals Isotopic Fractionation Accompanying CO2 Hydroxylation and Carbonate Precipitation from High pH Waters at The Cedars, California, USA

2021 ◽  
Author(s):  
John N. Christensen ◽  
James M. Watkins ◽  
Laurent S. Devriendt ◽  
Donald J. DePaolo ◽  
Mark E. Conrad ◽  
...  
Keyword(s):  
Isotopic Fractionation ◽  
Carbonate Precipitation ◽  
High Ph

scholarly journals Carbonate precipitation by the thermophilic archaeon <i>Archaeoglobus fulgidus</i>: a model of carbon flow for an ancient microorganism

2008 ◽  
Vol 5 (4) ◽  
pp. 3409-3432
Author(s):  
L. L. Robbins ◽  
K. A. Van Cleave ◽  
P. Ostrom
Keyword(s):  
Organic Carbon ◽  
Inorganic Carbon ◽  
Isotopic Fractionation ◽  
Archaeoglobus Fulgidus ◽  
Precipitation Process ◽  
Carbonate Precipitation ◽  
Lactate Oxidation ◽  
Thermophilic Archaeon ◽  
Microbial Carbonate ◽  
Microbial Carbonate Precipitation

Abstract. Microbial carbonate precipitation experiments were conducted using the archaeon bacteria Archaeoglobus fulgidus to determine chemical and isotopic fractionation of organic and inorganic carbon into mineral phases. Carbonate precipitation was induced in two different experiments using A. fulgidus to determine the relative abundance of organically derived carbon incorporated into carbonate minerals as well as to define any distinct phases or patterns that could be attributed to the precipitation process. One experiment used a medium containing 13C-depleted organic carbon and 13C-enriched inorganic carbon, and the other used a 14C-labeled organic carbon source. Results indicated that 0.9–24.8% organic carbon was incorporated into carbonates precipitated by A. fulgidus and that this process was mediated primarily by pH and CO2 emission from cells. Data showed that the carbon in the CO2 produced from this microorganism is incorporated into carbonates and that the rate at which precipitation occurs and the dynamics of the carbonate precipitation process are strongly mediated by the specific steps involved in the biochemical process for lactate oxidation by A. fulgidus.

scholarly journals Absence of hexavalent chromium in marine carbonates: implications for chromium isotopes as paleoenvironment proxy

2020 ◽  
Author(s):  
Ziyao Fang ◽  
Liping Qin ◽  
Wei Liu ◽  
Tao Yao ◽  
Xiaoyan Chen ◽  
...  
Keyword(s):  
Early Life ◽  
Direct Evidence ◽  
Atmospheric Oxygen ◽  
Sedimentary Rocks ◽  
Isotopic Fractionation ◽  
Isotopic Signature ◽  
Carbonate Precipitation ◽  
Valence States ◽  
Wide Range ◽  
Marine Carbonates

Abstract The oxygenation of Earth's atmosphere is widely regarded to have played an important role in early-life evolution. Chromium (Cr) isotopes recorded in sedimentary rocks have been used to constrain the atmospheric oxygen level (AOL) over geological times based on the fact that a positive Cr isotopic signature is linked to the presence of Cr(VI) as a result of oxidative continental weathering. However, there is no direct evidence of the presence of Cr(VI) in sedimentary rocks yet. Carbonates are most widely distributed over geological times and were thought to have incorporated Cr(VI) directly from seawater. Here, we present results of Cr valence states in carbonates which show Cr(III) is the dominant species in all samples spanning a wide range of geological times. These findings indicate that Cr(VI) in seawater was reduced either before or after carbonate precipitation, which might have caused Cr isotopic fractionation between seawater and carbonates, or marine carbonates preferentially uptake Cr(III) from seawater. As Cr(III) can come from non-redox Cr cycling, which also can cause isotopic fractionation, we suggest that positively fractionated Cr isotopic values do not necessarily correspond to the rise in AOL.

The orientation of sickle hemoglobin fibers within fascicles

1988 ◽  
Vol 46 ◽  
pp. 400-401
Author(s):  
Christopher A. Miller ◽  
Bridget Carragher ◽  
William A. McDade ◽  
Robert Josephs
Keyword(s):  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Relative Orientation ◽  
Unit Cell ◽  
Red Cell ◽  
High Ph ◽  
Sickle Hemoglobin ◽  
Polar Crystal ◽  
Helical Configuration

Highly ordered bundles of deoxyhemoglobin S (HbS) fibers, termed fascicles, are intermediates in the high pH crystallization pathway of HbS. These fibers consist of 7 Wishner-Love double strands in a helical configuration. Since each double strand has a polarity, the odd number of double strands in the fiber imparts a net polarity to the structure. HbS crystals have a unit cell containing two double strands, one of each polarity, resulting in a net polarity of zero. Therefore a rearrangement of the double strands must occur to form a non-polar crystal from the polar fibers. To determine the role of fascicles as an intermediate in the crystallization pathway it is important to understand the relative orientation of fibers within fascicles. Furthermore, an understanding of fascicle structure may have implications for the design of potential sickling inhibitors, since it is bundles of fibers which cause the red cell distortion responsible for the vaso-occlusive complications characteristic of sickle cell anemia.

Shumard Oaks Successfully Planted on High pH Soils

1985 ◽  
Author(s):  
Harvey E. Kennedy ◽  
Roger M. Krinard
Keyword(s):  
High Ph

Iron Deficiency Chlorosis and Seed Yield in Dry Edible Beans Grown on High-pH Calcareous Soils

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 444f-445
Author(s):  
J.W. Gonzales ◽  
D.P. Coyne ◽  
W.W. Stroup
Keyword(s):  
Iron Deficiency ◽  
Chlorophyll Content ◽  
Seed Yield ◽  
Calcareous Soils ◽  
Yield Reduction ◽  
Iron Deficiency Chlorosis ◽  
Breeding Lines ◽  
High Ph ◽  
The Third ◽  
Content Index

Iron deficiency chlorosis (FeDC) can cause significant seed yield reduction in dry beans (Phaseolus vulgaris L.) grown on high-pH calcareous soils. To determine the effects of FeDC on seed yield, and the effect of Fe-spray as a correction factor for FeDC, 22 breeding lines/cultivars were planted on high-pH (8.0), calcareous (3.2–3.5 calcium carbonate equivalent), and low-Fe (1.8–4.2 ppm DTPA) sandy clay loam Tripp soils at Mitchell and Scottsbluff in western Nebraska. A split-plot design was used with Fe treatments as main plots and breeding lines/cultivars as subplots. Three foliar sprays of Fe-EDDHA (2.4 kg·ha–1) were applied at V4, R5, and R7 dry bean growth stages, during 1996 and 1997. Leaf chlorosis was measured simultaneously by using a Minolta Chroma-meter (CIE L* a* b* color space system), a Minolta Chlorophyll-meter (chlorophyll content index), and by visual ratings (1 = normal green to 5 = severe chlorosis). In 1996 no significant Fe-spray × line interaction (P = 0.776) and Fe-spray effect (P = 0.884) on seed yield was observed. Breeding lines showed significant differences in seed yield (P = 0.0001) with WM2-96-5 being the highest-yielding line (4047 kg·ha–1). In 1997 a significant Fe spray × line interaction (P = 0.029) was observed. The cultivar Chase without Fe spray (3375 kg·ha–1), and lines WM2-96-5 (3281 kg·ha–1), WM2-96-8 (3171 kg·ha–1) with Fe spray were the highest yielding entries under those treatments. Differences in visual ratings after the third Fe spray in 1997 were significant (P = 0.004) for Fe spray × line interaction. In 1996 visual ratings were different only for breeding lines. Chlorophyll content index showed a significant Fe spray × line interaction after the second Fe spray (P = 0.022) and after the third Fe spray (P = 0.0003) in 1997.

Sign in / Sign up

Export Citation Format

Share Document