How does acid treatment to remove carbonates affect the isotopic and elemental composition of soils and sediments?

2008 ◽  
Vol 5 (1) ◽  
pp. 33 ◽  
Author(s):  
Milena Fernandes ◽  
Evelyn Krull
Keyword(s):  
Organic Carbon ◽  
Isotopic Analysis ◽  
Isotopic Signature ◽  
Isotopic Signatures ◽  
Carbon And Nitrogen ◽  
Isotopic Shifts ◽  
Soils And Sediments ◽  
Significant Difference ◽  
Acid Treatments

Environmental context. The ability to accurately determine the elemental and isotopic composition of soils and sediments has important implications to our quantitative understanding of global biogeochemical cycles. However, the analysis of organic carbon in solid matrices is a time-consuming task that requires the selective removal of carbonates, a treatment that has the potential to significantly alter the composition of the original sample. In the present work, we compare three of the most common acid treatments used for carbonate removal, and critically evaluate their effect on the content and isotopic signature of organic carbon and nitrogen in both soils and sediments. Abstract. In the present work, we compared the efficacy of three acid treatments in removing carbonates from soils and sediments for elemental and isotopic analysis. The methods tested were (1) refluxing with H2SO3; (2) in situ treatment with H2SO3 in silver capsules; and (3) treatment with HCl followed by rinsing with water. Refluxing with H2SO3 led to substantial losses of organic carbon and nitrogen, but comparatively small nitrogen isotopic shifts. The in situ treatment was inadequate for carbonate-rich samples (contents ≥30%) as a consequence of the formation of a mineral precipitate. Treatment with HCl led to substantial losses of nitrogen from carbonate-rich samples, and deviations in nitrogen isotopic signatures (δ15N) of up to 3.7‰. δ15N values showed no significant difference between acid-treated and untreated samples or between treatments, although variability was high and influenced by sample composition. Carbonate-poor samples showed no statistical difference in δ13C values between treatments, whereas carbonate-rich samples tended to be more 13C-depleted when treated with HCl, potentially suggesting the preferential preservation of 13C-depleted compounds (e.g. lipids or lignin).

The effects of some grazed tropical grass-legume mixtures and nitrogen fertilized grass on total soil nitrogen, organic carbon, and subsequent yields of Sorghum vulgaris

1967 ◽  
Vol 7 (24) ◽  
pp. 66 ◽  
Author(s):  
RJ Jones
Keyword(s):  
Organic Carbon ◽  
Soil Nitrogen ◽  
Crop Yields ◽  
Low Fertility ◽  
Apparent Lack ◽  
Carbon And Nitrogen ◽  
Total Soil ◽  
Significant Difference ◽  
Nitrogen Treatments ◽  
Total Soil Nitrogen

Mixtures of some tropical legumes and Paspalum plicatulum (Michx) cv. Hartley, and stands of P. plicatulum were fertilized with urea at 100 and 200 lb nitrogen an acre a year, and were intermittently grazed by cattle over a period of four years. Soil analyses for organic carbon and for total soil nitrogen in the fourth year of the pasture phase revealed large treatment effects in three of the five replicates. These three replicates which were on a podsolic soil were lower in fertility than the remaining two on a latosolic soil. Soil nitrogen at the 0-3 inch depth in the high nitrogen treatment, and in two Phaseolus atropurpureus D.C. treatments was significantly higher than the control (P<0.05). Organic carbon at the 0-3 inch depth was significantly higher than the control (P<0.05) in the nitrogen treatments and in one of the P. atropurpureus treatments. For both soil nitrogen and organic carbon the Lotononis bainesii Bak. treatment did not differ from the control. There was no significant difference between treatments for soil nitrogen or organic carbon at the 3-6 inch depth though trends were similar to those at 0-3 inches. Organic carbon and nitrogen were closely correlated for all treatments at both depths, and there were no significant differences in the C : N ratio in any treatment. Yields of sorghum grown as a test crop after the pastures were significantly correlated with soil nitrogen values in the three low fertility replicates. A high correlation (r = +0.976) also existed between yields of nitrogen obtained in the pasture phase and test crop yields of nitrogen for all treatments except L. bainesii. Reasons for the apparent lack of improvement in soil nitrogen and carbon on the higher fertility replicates and for the poor test crop yields following L. bainesii are discussed.

scholarly journals Isotopic composition of cow tail switch hair as an information archive of the animal environment

2003 ◽  
pp. 147-152 ◽  
Author(s):  
M. Schwertl ◽  
C. Matthew ◽  
K. Auerswald ◽  
H. Schnyder ◽  
K. Crook
Keyword(s):  
Average Distance ◽  
Nutritional Ecology ◽  
Isotopic Analysis ◽  
Isotopic Signature ◽  
Animal Tissue ◽  
Scientific Investigation ◽  
Isotopic Abundance ◽  
Proof Of Concept ◽  
Isotopic Signatures ◽  
C And N

Using isotopic signatures from animal tissue, it is possible to recover certain information about the environment of the animal - notably the diet - at the time the hair was laid down. In the case of tail switch hair of cattle, a single hair may often represent an archive of information spanning a year or more in time. Isotopic analysis by mass spectrometry is now becoming cheap enough to be considered accessible for routine diagnostic or scientific investigation. The ratios of 13carbon (C):12carbon and 15nitrogen (N):14nitrogen ar e ideal for such investig ation, since C and N are constituents of all animal proteins. This paper explains the theory of isotopic analysis in layman's terms, and repor ts an exper iment in which tail switch hair of 9 cattle from three Northland dairy farms was analysed in a 'proof of concept' study, to demonstrate the information-retrieval potential offered by isotopic analysis. Changes in isotopic abundance are measured in parts per thousand (, ‰). When matching signatures on replicate hairs, the average distance from the 'interpolation' line was ± 0.13‰ for 13C, and ± 0.11‰ for 15N. In contrast to this, differences in 13C between different hair segments analysed exceeded 11‰ , while between farm dif ferences in 15N exceeded 2.0‰ . We suggest possible reasons for these differences in isotopic signature. Keywords: 13C, 15 N, isotopic archive, nutritional ecology, stable isotope

scholarly journals The Effect of Increased Ozone Levels on the Stable Carbon and Nitrogen Isotopic Signature of Wheat Cultivars and Landraces

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 883
Author(s):  
Melissa Chang-Espino ◽  
Ignacio González-Fernández ◽  
Rocío Alonso ◽  
Jose Luis Araus ◽  
Victoria Bermejo-Bermejo
Keyword(s):  
Stomatal Conductance ◽  
Nitrogen Concentration ◽  
Isotopic Signature ◽  
Ozone Exposure ◽  
Negative Effects ◽  
Strong Negative Correlation ◽  
Isotopic Signatures ◽  
Carbon And Nitrogen ◽  
Grain Nitrogen ◽  
Δ15n And Δ13c

Several studies have highlighted the negative effects of ozone (O3) on wheat development and productivity. The negative effects of O3 are mediated by changes in photosynthetic carbon and nitrogen metabolism, which are difficult and time-consuming to assess and are thus only measured sporadically throughout the plant cycle. Stable isotope measurements in grains can help integrate the effects of chronic O3 exposure over the lifespan of the plant. This particular study focuses on the extent to which the stomatal conductance and productivity of Mediterranean wheat are related to carbon and nitrogen isotopic signatures under chronic O3 exposure. An open top chamber experiment was designed to analyse the effects of the pollutant on 12 Spanish wheat genotypes, which included modern cultivars, old cultivars and landraces. Four O3 treatments were considered. Stomatal conductance (gs) measurements were carried out during anthesis, and yield and nitrogen content parameters were taken at maturity, along with the carbon (δ13C) and nitrogen (δ15N) isotopic composition measured in grains. Modern and old cultivars responded similarly to O3 and were sensitive to the pollutant regarding yield parameters and gs, while landraces were more O3-tolerant. Grain δ13C had a strong negative correlation with grain yield and stomatal conductance across genotypes and O3 conditions, and increased under higher O3 concentrations, showing its capacity to integrate O3 stress throughout the wheat cycle. Meanwhile, a higher nitrogen concentration in grains, coupled with smaller grains, led to an overall decreased grain nitrogen yield under higher O3 concentrations. This nitrogen concentration effect within the grain differed among genotypes bred at different ages, following their respective O3-sensitivity. δ15N showed a possible indirect effect of O3 on nitrogen redistribution, particularly under the highest O3 concentration. The correlations of δ15N and δ13C to the usual effects of ozone on the plant suggest their potential as indicators of chronic ozone exposure.

scholarly journals The Carbon and Nitrogen Isotope Characteristics of Type Ib-IaA Cuboid Diamonds from Alluvial Placers in the Northeastern Siberian Platform

2017 ◽  
Author(s):  
Dmitry Zedgenizov ◽  
Vadim Reutsky ◽  
Michael Wiedenbeck
Keyword(s):  
Siberian Platform ◽  
Secondary Ion Mass Spectrometry ◽  
Nitrogen Isotope ◽  
Isotopic Signature ◽  
Crustal Material ◽  
Aggregation State ◽  
Carbon And Nitrogen ◽  
Three Samples ◽  
Nitrogen Contents

Cuboid diamonds are particularly common in the placers of the northeastern Siberian platform but their origin remains unclear. These crystals usually range in color from dark yellow&nbsp; to orange and more interestingly, are characterized by unusual low aggregated nitrogen impurities (non-aggregated C-center) suggesting a short residence time and/or low temperatures at which they have been stored in the mantle. In order to track possible isotopic signature that could help deciphering cuboid diamond's crystallization processes, &delta;13C values, &delta;15N values and nitrogen contents have been determined in-situ in three samples using secondary ion mass spectrometry (SIMS), whereas nitrogen aggregation state have been determined by FTIR spectroscopy. The samples fall out the &delta;13C vs. &delta;15N field of canonical mantle composition. Different scale of carbon and nitrogen fractionation may produce the observed variations. Alternatively, mixing of mantle and crustal material would obscure initial co-variations of &delta;13C values with &delta;15N or nitrogen content.

scholarly journals Changes in Particulate and Mineral Associated Organic Carbon with Land Use in Contrasting Soils

2019 ◽  
Author(s):  
Sabina Yeasmin ◽  
Balwant Singh ◽  
Cliff T. Johnston ◽  
Donald L. Sparks ◽  
Quan Hua
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Organic Carbon ◽  
Land Use Change ◽  
Crop Residues ◽  
Isotopic Signature ◽  
Surface Soils ◽  
Isotopic Signatures ◽  
Mineral Associations ◽  
C Stock

Abstract. Soil organic carbon (OC) is the largest terrestrial C stock and soils' capacity to preserve OC varies with many factors including land use, soil type and depth. We investigated the effect of land use change on particulate organic matter (POM) and mineral-associated organic matter (MOM) in soils. Surface (0–10 cm) and sub-surface (60–70 cm) soil samples were collected from paired-sites (native and cropped lands) of four contrasting soils. Bulk soils were isolated into POM and MOM fractions, which were analysed for mineralogy, OC and nitrogen, isotopic signatures and 14C content. POMs of surface soils were relatively unaffected by land use change, possibly because of continuous input of crop residues, while corresponding POM in sub-surface lost more OC. In surface soils, oxides-dominated MOM lost more OC than phyllosilicates- and quartz -dominated MOM, which is attributed to diverse OM input and the extent of OC saturation limit of soils. In contrast, oxides-associated fractions were less affected in the sub-surface soils than the other two MOM fractions, possibly due to OC protection via organo–mineral associations. Changed isotopic signature (linked with vegetation) across the fractions suggested that fresh crop residues constituted the bulk of OM in surface soils (supported by greater 14C). Increased isotopic signatures and lower 14C in sub-surface MOM fractions suggested the association of more microbially processed, aged OC in oxides-rich fractions than other MOMs. Results reveal that quantity and quality of OC after land use change was influenced by the nature of C input in surface soils and by mineral-organic association in sub-surface soils.

scholarly journals The Effect of Storage on the Radiocarbon, Stable Carbon and Nitrogen Isotopic Signatures and Concentrations of Riverine DOM

Radiocarbon ◽  
2010 ◽  
Vol 52 (3) ◽  
pp. 1113-1122 ◽  
Author(s):  
P Gulliver ◽  
S Waldron ◽  
E M Scott ◽  
C L Bryant
Keyword(s):  
Stream Water ◽  
River System ◽  
Isotopic Signature ◽  
Health Impacts ◽  
Stable Carbon ◽  
Isotopic Signatures ◽  
Carbon And Nitrogen ◽  
Storage Method ◽  
Baseline Values ◽  
Chemical Preservatives

Chemical preservatives (e.g. mercuric chloride) are routinely added to freshwater samples to prevent biological activity compromising the isotopic signature of dissolved organic matter (DOM) with time. However, alternative preservation methods are needed due to regulations restricting the use of preservatives with potentially adverse environmental and health impacts, rendering such additions unviable. This study investigates whether a non-chemical storage method is sufficient to maintain the radiocarbon and stable carbon and nitrogen signatures of freshwater DOM from a low order river system draining a peaty catchment. Some 50 L of stream water were collected in 1 plastic carbuoy and, within 24 hr, 1-L aliquots were transferred to acid-washed plastic bottles. Five aliquots were analyzed immediately to determine the baseline values for 14C (pMC), δ13C (VPDB‰), δ15N (AIR‰), %C (mg L–1), and %N (mg L–1). Of the remaining subsamples, 20 were frozen and a further 20 refrigerated at <4 °C. After 7, 30, 90, and 180 days, 5 frozen and 5 refrigerated aliquots were analyzed in the same manner as the baseline aliquots. Analysis of the results shows that there is no statistically significant interaction between the variables storage method or length of storage for any of the determinants. Storage method has a statistically significant effect on 14C (pMC) and [C] (mg L–1). Length of storage has a statistically significant effect on δ13C (VPDB‰), [C] (mg L–1), and [N] (mg L–1) values. Neither storage method nor length of storage appear to have a statistically significant effect on 815N (AIR‰) values.

Groundwater–Surface Water Relationships in Boreal Forest Watersheds: Dissolved Organic Carbon and Inorganic Nutrient Dynamics

1989 ◽  
Vol 46 (1) ◽  
pp. 41-49 ◽  
Author(s):  
T. E. Ford ◽  
Robert J. Naiman
Keyword(s):  
Surface Water ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Nutrient Dynamics ◽  
Total N ◽  
Carbon And Nitrogen ◽  
Significant Difference ◽  
Forest Watersheds ◽  
Study Sites ◽  
Total P

Dissolved organic carbon (DOC) and inorganic nutrients (NH4-N, NO3-N, soluble total N, PO4-P, soluble total P, and Si) were measured in ground and surface waters in the Matamek River drainage network, Quebec, Canada. In general, concentrations of carbon and nitrogen were significantly higher in groundwater than in surface water (up to 340% for DOC and up to 700% for total N). No significant difference was detected for phosphorus whereas considerable variation occurred for silicon, with significantly higher groundwater concentrations at 50% of the study sites. We hypothesize that (1) groundwater is a source of DOC and nitrogen in these systems and (2) nutrients introduced through groundwater seepage are rapidly utilized via oxidative, biotic processes within the hyporheal zone or at the sediment–water interface.

The Blackstones Bank igneous complex: geochemistry and crustal context of a submerged Tertiary igneous centre in the Scottish Hebrides

2002 ◽  
Vol 139 (2) ◽  
pp. 199-207 ◽  
Author(s):  
A. P. DICKIN ◽  
G. P. DURANT
Keyword(s):  
Continental Shelf ◽  
Isotopic Analysis ◽  
Isotopic Signature ◽  
The West ◽  
Early Proterozoic ◽  
Isotopic Signatures ◽  
Crustal Rocks ◽  
Published Evidence ◽  
Igneous Province ◽  
Proterozoic Basement

The Blackstones Bank, located about 60 km WSW of the Isle of Mull in Western Scotland, is a submarine plutonic complex in the British Tertiary Igneous Province. Geochemical and isotopic analysis of gabbros, microgabbros and basic dykes shows that the magmas interacted strongly with crustal rocks during their emplacement. The isotopic signature of the contaminated Tertiary intrusions shows no evidence of any interaction with Archaean basement, despite the location of the Blackstones complex to the west of the Great Glen fault. Instead, the Blackstones rocks have crustal signatures resembling the Proterozoic basement and cover rocks of western Islay. It is therefore inferred that Early Proterozoic crust extends to the west of the Great Glen fault at this point on the Scottish continental shelf. In addition, the occurrence of similar isotopic signatures in Tertiary igneous rocks east of the Loch Gruinard fault confirms that Early Proterozoic basement extends under the Grampian block of mainland Scotland. When combined with published evidence from the Rockall bank, the new data constrain the location of an Archaean–Proterozoic crustal suture with a WNW trajectory which cuts across the continental shelf of northwest Britain.

scholarly journals Comparison on soil organic carbon and nitrogen dynamics between urban impervious surfaces and vegetation

2021 ◽  
Author(s):  
Xiaolin Dou ◽  
Meng Lu ◽  
Liding Chen
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Isotopic Analysis ◽  
Bare Soil ◽  
Soil C ◽  
Carbon And Nitrogen ◽  
Stable Isotopic ◽  
Carbon And Nitrogen Dynamics ◽  
Urban Impervious Surfaces ◽  
A Minor

The soil carbon (C) and nitrogen (N) dynamic was usually considered as a minor change based on a static process in the sealed soil under decades of impervious surface (IS). However, no systematic studies concerning the soil organic carbon (SOC) and nitrogen (SON) dynamic were conducted under IS in contrast with urban vegetation (i.e., forest, grass). Here we utilized fractional distillation of soils as well as stable isotopic analysis to examine soil C&N cycles after 20 and 30 years of vegetation planting and IS construction in Guangzhou and Shenzhen, Pearl River Delta, China. Soil samples including bare soil (CK) and four land use treatments were split into different chemical fractions. Then we analyzed the C&N content, C/N ratio, δ13C, δ15N, C&N recalcitrant indices (RIC, RIN), and the mean residence time (MRT). We found that the soil C&N increased first (i.e., 20 years) because of enhanced C&N stocks in both labile (LP) and recalcitrant pool (RP), and then stabilized or decreased (i.e., 30 years) with the IS ages in both cities. IS had a lower SOC decomposition rate and thus resulted in the five to ten times longer MRT (about 259–465 years) than that in vegetated soils (about 39–55 years). Moreover, the SOC&SON always showed a decoupling relation in labile pools (i.e., LC and LN) in forests in both cities. The study showed the IS remarkably altered the soil C&N dynamics, showing a great difference in SOC&SON fractions composition and turnover compared with vegetation.

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