Iron Redistribution Upon Thermokarst Processes in the Yedoma Domain

Ice-rich permafrost has been subject to abrupt thaw and thermokarst formation in the past and is vulnerable to current global warming. The ice-rich permafrost domain includes Yedoma sediments that have never thawed since deposition during the late Pleistocene and Alas sediments that were formed by previous thermokarst processes during the Lateglacial and Holocene warming. Permafrost thaw unlocks organic carbon (OC) and minerals from these deposits and exposes OC to mineralization. A portion of the OC can be associated with iron (Fe), a redox-sensitive element acting as a trap for OC. Post-depositional thaw processes may have induced changes in redox conditions in these deposits and thereby affected Fe distribution and interactions between OC and Fe, with knock-on effects on the role that Fe plays in mediating present day OC mineralization. To test this hypothesis, we measured Fe concentrations and proportion of Fe oxides and Fe complexed with OC in unthawed Yedoma and previously thawed Alas deposits. Total Fe concentrations were determined on 1,292 sediment samples from the Yedoma domain using portable X-ray fluorescence; these concentrations were corrected for trueness using a calibration based on a subset of 144 samples measured by inductively coupled plasma optical emission spectrometry after alkaline fusion (R2 = 0.95). The total Fe concentration is stable with depth in Yedoma deposits, but we observe a depletion or accumulation of total Fe in Alas deposits, which experienced previous thaw and/or flooding events. Selective Fe extractions targeting reactive forms of Fe on unthawed and previously thawed deposits highlight that about 25% of the total Fe is present as reactive species, either as crystalline or amorphous oxides, or complexed with OC, with no significant difference in proportions of reactive Fe between Yedoma and Alas deposits. These results suggest that redox driven processes during past thermokarst formation impact the present-day distribution of total Fe, and thereby the total amount of reactive Fe in Alas versus Yedoma deposits. This study highlights that ongoing thermokarst lake formation and drainage dynamics in the Arctic influences reactive Fe distribution and thereby interactions between Fe and OC, OC mineralization rates, and greenhouse gas emissions.

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ICP/XRF Analysis for Trace Elements in Soil Samples from Gezira and Suki Schemes, Sudan

International Journal of Scientific Research and Management ◽

10.18535/ijsrm/v9i02.c01 ◽

2021 ◽

Vol 9 (02) ◽

pp. 32-39

Author(s):

Marwa M Adam ◽

Mustafa M Osman ◽

Ahmed Salih Elhag ◽

Mohamed A Elsheikh

Keyword(s):

Inductively Coupled Plasma ◽

Optical Emission ◽

Hierarchical Cluster ◽

Soil Samples ◽

Emission Spectrometry ◽

Inductively Coupled ◽

Elemental Concentrations ◽

Accuracy Of Measurements ◽

Significant Difference ◽

Plasma Optical Emission Spectrometry

In the present study, soil samples have been collected from two different agriculture areas: Gezira and Suki schemes in Sudan, The elemental concentrations for Cr, Ni, Cu, Zn, and Pb have been determined using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) and X-ray Fluorescence spectrometry (XRF). The accuracy of measurements has been investigated by using ISE (PT) 1&4 and fortified samples for ICP, IAEA-Soil-7 XRF, respectively. A good agreement was found between certified and measured values. The average elemental concentrations by ICP of these elements Cr, Ni, Cu, Zn, and Pb in loc1 were found as follows: 84.7, 48.15, 33.5, 65.43, and 12.57 ppm, respectively. While the results obtained in loc2 were found as follows: 105, 65.1, 41.3, 55.4, and 12.74 ppm, respectively. The average elemental concentrations by XRF of these elements Cr, Ni, Cu, Zn, and Pb in loc1 were found as follows: 77.21, 43.72, 27.62, 86.96, and 18.74 ppm, respectively. While the results obtained in loc2 were found as follows: 123.33, 57.41, 35.99, 98.85, and 16.43 ppm, respectively. A statistical test (t-test) was applied to the data of both methods without any significant difference between the two techniques. The results obtained were compared to WHO permissible limits. Correlations between different elements were performed. Hierarchical cluster analysis was done for the data. The average elemental concentrations were calculated and compared with data from the literature.

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The silicon content of beer and its bioavailability in healthy volunteers

British Journal Of Nutrition ◽

10.1079/bjn20031082 ◽

2004 ◽

Vol 91 (3) ◽

pp. 403-409 ◽

Cited By ~ 76

Author(s):

Supannee Sripanyakorn ◽

Ravin Jugdaohsingh ◽

Hazel Elliott ◽

Caroline Walker ◽

Payal Mehta ◽

...

Keyword(s):

Healthy Volunteers ◽

Inductively Coupled Plasma ◽

Human Subjects ◽

Optical Emission ◽

Positive Control ◽

Emission Spectrometry ◽

Orthosilicic Acid ◽

Inductively Coupled ◽

Significant Difference ◽

Si Content

Dietary Si, as soluble orthosilicic acid (OSA), may be important for the growth and development of bone and connective tissue. Beer appears to be a major contributor to Si intake, although the Si content of beer and its bioavailability in human subjects have not been well established. Here we investigated the Si content of different beers and then estimated Si absorption from beer in healthy volunteers. The Si content of seventy-six different beers was estimated using inductively coupled plasma optical emission spectrometry and one of the beers, used in the ingestion study, was ultrafiltered to determine OSA content. Next, following the ingestion of 0·6 litres beer (22·5mg Si; 4·6% (v/v) ethanol), serum and urinary Si levels were measured in nine healthy volunteers over a 6h period. A solution of OSA was similarly investigated as a positive control and water and 4·6% ethanol as negative controls. The mean Si level of beer was 19·2 (SD 6·6) mg/l; the median Si level was 18·0mg/l. There was no significant difference in the Si levels of the different beers by geographical origin or type of beer. Serum and urinary Si levels increased considerably following the ingestion of beer or a solution of OSA but not with the ingestion of either 4·6% ethanol or water. The ultrafilterability of Si from beer (about 80%) and its absorption in volunteers (about 55%) was comparable with that of a solution of OSA suggesting that Si in beer is present chiefly in a monomeric form and is readily bioavailable.

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Copper(II) and Sulfur Dioxide in Chardonnay Juice and Shiraz Must: Impact on Volatile Aroma Compounds and Cu Forms in Wine

Beverages ◽

10.3390/beverages5040070 ◽

2019 ◽

Vol 5 (4) ◽

pp. 70

Author(s):

Xinyi Zhang ◽

Nikolaos Kontoudakis ◽

John W. Blackman ◽

Andrew C. Clark

Keyword(s):

Inductively Coupled Plasma ◽

Grape Juice ◽

Optical Emission ◽

Emission Spectrometry ◽

Inductively Coupled ◽

Volatile Aldehyde ◽

Wine Composition ◽

Significant Difference ◽

Bottle Aging ◽

Plasma Optical Emission Spectrometry

This work outlines the influence of Cu(II) and SO2 concentrations in Chardonnay juice or Shiraz must on the respective wine composition. Analyses were conducted pre- and post-fermentation, after cold stabilization, after bentonite treatment (Chardonnay only), at bottling, and 15 months after bottling. The quantification of total Cu was conducted by inductively coupled plasma optical emission spectrometry and free Cu by stripping potentiometry. Low molecular weight sulfur compounds, volatile aldehyde compounds, and general volatile compounds, including esters and terpenes, were quantified with gas-chromatography- or liquid-chromatography-QQQ-mass spectrometry. For Chardonnay, increased Cu concentration in the juice resulted in higher concentrations of Cu in the respective wine, while Shiraz wines showed no significant difference. Increased Cu addition to Chardonnay juice also produced significantly higher concentrations of H2S, 3-methylbutanal, and methional, but lower concentrations of methanethiol and phenylacetaldehyde, while SO2 addition increased 3-methylbutanal and phenylacetaldehyde, and decreased methanethiol production from post-fermentation to post-bottle aging. For the Shiraz, SO2 led to higher concentrations of H2S, and both SO2 and Cu addition increased the concentrations of hexanal, 3-methylbutanal, and phenylacetaldehyde in wine, but this effect diminished after cold stabilization. This study shows that SO2 and Cu in grape juice/must can have long-term implications for wine composition.

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