14C Content Research Articles

Protected palmitic acid to mitigate milk fat depression in grazing Holstein cows in the Mexican Highlands

ABSTRACT The cis-9 trans-11 and trans-10 cis-12 isomers of conjugated linoleic acid (CLA) are associated with anticancer and lipolytic effects in tissues, respectively, but in lactating cows, the latter isomer reduces the milk fat concentration, a detrimental aspect for the dairy industry, as it reduces the yield of milk derivatives. Therefore, the objective of this study was to evaluate the effect of providing protected palmitic acid (PA P ) to grazing lactating Holstein cows supplemented with soybean oil as a source of conjugated linoleic acid, on milk production, fat concentration and mitigation of milk fat depression. Nine multiparous Holstein cows were used, distributed in three groups of three cows each, with initial means of days in milk, live weight, milk production, and number of calvings: 124 ± 16 days, 494 ± 53 kg, 20.9 ± 1.3 kg, and 3.2 ± 2.2, respectively. A crossover design with three treatments was used: control (base diet, BD, = grazing +4 kg concentrate without soybean oil + 2.5 kg corn silage), soybean oil (BD with inclusion of 300 g dry basis soybean oil cow−1 day−1), and soybean oil + PA P (BD with inclusion of 300 g dry basis soybean oil and 412 g PA P cow−1 day−1). The groups of cows were on rotational grazing in a mixed pasture of Alfalfa (Medicago sativa) and Orchard grass (Dactylis glomerata). The variables evaluated were as follows: dry matter intake (DM), milk production, concentration of protein, fat and lactose in milk, and milk fat profile. Statistical analysis was through PROC MIXED and comparison of means with Tukey’s test (p < 0.05). There were no differences (p > 0.05) between treatments in dry matter intake, milk production or milk protein and lactose content. But the addition of PA P in the cow diet increased fat-corrected milk production (p = 0.010), yield (p = 0.030) and fat concentration (p = 0.040), and improved the milk fatty acid profile, by increasing (p = 0.010) the concentration of cis-9, trans-11 CLA in milk fat. Soybean oil supplementation in the diet of grazing lactating cows showed no differences in productive variables, and did not cause the expected milk fat depression. However, combining soybean oil with PA P improved the fatty acid profile, increasing the cis-9, trans-11 isomer CLA and palmitic acid in milk fat, with higher yield and fat concentration.

BDH1 identified by transcriptome has a negative effect on lipid metabolism in mammary epithelial cells of dairy goats

BackgroundThe 3-hydroxybutyrate dehydrogenase 1 (BDH1) mainly participates in the regulation of milk fat synthesis and ketone body synthesis in mammary epithelial cells. In our previous study, BDH1 was identified as a key candidate gene regulating lipid metabolism in mammary glands of dairy goats by RNA-seq. This study aimed to investigate the effect of BDH1 on lipid metabolism in mammary epithelial cells of dairy goats (GMECs).ResultsThe results suggest that BDH1 plays a significant role in reducing triacylglycerol content and lipid droplet accumulation in GMECs (p < 0.05). Overexpression of BDH1 significantly decreased the expression of lipid metabolism-related genes (SREBF1 and GPAM) and reduced the levels of C14:0 and C17:1, while increasing FABP3 expression and C10:0 concentration (p < 0.05). Interference with BDH1 significantly increased the expression of SREBF1 and GPAM and the concentration of C14:0, C15:1, and C20:1, but significantly decreased FABP3 and C18:0 (p < 0.05). Treatment of GMECs with β-hydroxybutyric acid (R-BHBA) significantly decreased the expression of FASN, ACACA, LPL, SREBF1, FABP3, ACSL1, GPAM, DGAT1, and triacylglycerol content, while significantly increasing the expression of BDH1 (p < 0.05). Interference with BDH1 rescued the reduction of cellular TAG content and the expression of FASN, LPL, SREBF1, ACSL1, and GPAM in BHBA-treated GMECs.ConclusionIn conclusion, BDH1 negatively regulates lipid metabolism in mammary glands of dairy goats. Furthermore, it may mitigate the inhibitory effect of R-BHBA on lipid metabolism in GMECs.Graphical BDH1 serves as a negative regulator of milk lipid synthesis in GMECs, and BDH1 counteracts the inhibitory effect of R-BHBA on lipid synthesis in mammary epithelial cells of dairy goats.

Radiocarbon measurements of dissolved inorganic carbon (DIC) in sediment porewater and seawater at AWI MICADAS

Abstract Radiocarbon (14C) measurements on dissolved inorganic carbon (DIC) are a powerful tool to trace water masses and carbon cycling in the ocean. Existing methodologies to determine the 14C content of seawater DIC requires large volumes of sample (usually &gt;100 mL) and specialized graphitization techniques to achieve the accuracy and precision needed for meaningful data interpretation. The advancement of the CO2 gas ionization accelerator mass spectrometry (AMS) technique today allows routine 14C measurements on small samples (&lt;100 µgC) and may thus permit reducing the sample volumes needed to determine 14C content of seawater DIC to ∼2 mL. The proposed method utilizes the carbonate handling system (CHS), gas interface system (GIS) and MICADAS AMS, and provides good accuracy but reduced precision compared to established methods. Good accuracy is shown by comparing results for a marine in-house DIC standard and a DIC seawater profile from Antarctica between the proposed CHS-GIS-MICADAS approach and reference measurements conducted on the same material at established laboratories (ETH and NOSAMS). Further, two sedimentary porewater profiles from a fjord system in Svalbard are presented. Despite good agreement, the precision of the CHS-GIS-MICADAS approach is reduced, potentially limiting possible interpretations on seawater DIC. Nonetheless, the reduction of sample volumes proves particularly helpful to analyze porewater DIC from sediment cores, where sample material is notoriously limited, reduces the required amounts of toxic HgCl2 and simplifies expedition logistics.

Investigating the impact of COVID-19 on the atmospheric 14C trend and fossil carbon load at urban and background sites in Hungary

Abstract The study analyses in situ CO2 mole fraction, 14CO2, and fossil based excess CO2 mole fraction (Cfoss) data at Hegyhátsál (HUN) rural monitoring station (Central Europe) supplemented by passive monitoring of 14C content of tree-rings. Through the observed period (2014–2020) we focused on revealing trends in atmospheric CO2 and 14C levels, particularly during the year of the first COVID lockdown, in comparison to the preceding five years. In addition, monthly integrated samples of atmospheric CO2 and tree-rings from the six years were subjected to 14C analysis. The passive tree-ring measurements focuses on two major urban areas (Budapest and Debrecen) in Hungary, along with the rural monitoring site. Results show a steady increase in CO2 levels at HUN between 2014 and 2020. The calculated fossil based excess CO2 concentrations for the initial year of COVID are in good agreement with the previous five-year averages both at 115 m and 10 m elevations. These results also show seasonal variations of CO2 mole fractions, peaking in winter and decreasing in summer. Tree-ring results from Debrecen show a good alignment with the results of the atmospheric monitoring station, and it does not show a significant fossil contribution in the urban background area during the vegetation periods. Tree-ring results from Budapest show a stronger fossil contribution compared to the Debrecen ones. Our atmospheric CO2 results do not show a large decrease in fossil CO2 atmospheric contribution during the first lockdown. We found that the use of this passive CO2 monitoring technique can provide a valuable tool for investigating such differences.

Impact of dietary lysophospholipids supplementation on growth performance, meat quality, and lipid metabolism in finishing bulls fed diets varying in fatty acid saturation

BackgroundThe objective of this study was to evaluate the effects of dietary fatty acids (FA) saturation and lysophospholipids supplementation on growth, meat quality, oxidative stability, FA profiles, and lipid metabolism of finishing beef bulls. Thirty-two Angus bulls (initial body weight: 623 ± 22.6 kg; 21 ± 0.5 months of age) were used. The experiment was a completely randomized block design with a 2 × 2 factorial arrangement of treatments: 2 diets with FA of different degree of unsaturation [high saturated FA diet (HSFA) vs. high unsaturated FA diet (HUFA)] combined with (0.075%, dry matter basis) and without lysophospholipids supplementation. The bulls were fed a high-concentrate diet (forage to concentrate, 15:85) for 104 d including a 14-d adaptation period and a 90-d data and sample collection period.ResultsNo interactions were observed between dietary FA and lysophospholipids supplementation for growth and meat quality parameters. A greater dietary ratio of unsaturated FA (UFA) to saturated FA (SFA) from 1:2 to 1:1 led to lower DM intake and backfat thickness, but did not affect growth performance and other carcass traits. Compared with HSFA, bulls fed HUFA had greater shear force in Longissimus thoracis (LT) muscle, but had lower intramuscular fat (IMF) content and SOD content in LT muscle. Compared with HUFA, feeding the HSFA diet up-regulated expression of ACC, FAS, PPARγ, and SCD1, but down-regulated expression of CPT1B. Compared with feeding HSFA, the HUFA diet led to greater concentrations of c9-C18:1 and other monounsaturated FA in LT muscle. Feeding HUFA also led to lower plasma concentrations of cholesterol, but there were no interactions between FA and lysophospholipids detected. Feeding lysophospholipids improved growth and feed conversion ratio and altered meat quality by increasing muscle pH24h, redness values (24 h), IMF content, and concentrations of C18:3, C20:5 and total polyunsaturated fatty acids. Furthermore, lysophospholipids supplementation led to lower malondialdehyde content and up-regulated the expression of ACC, FAS, and LPL in LT muscle.ConclusionsResults indicated that supplementing a high-concentrate diet with lysophospholipids to beef bulls can enhance growth rate, feed efficiency, meat quality, and beneficial FA. Increasing the dietary ratio of UFA to SFA reduced DM intake and backfat thickness without compromising growth, suggesting potential improvements in feed efficiency.

Erythrocyte Fatty Acid Patterns Are Associated with Skeletal Muscle Mass in Chinese Children.

Nutritional factors are important for skeletal muscle mass and grip strength development in children. This study aimed to investigate the relationship between erythrocyte membrane fatty acid patterns (FAPs) and skeletal muscle mass and grip strength in children. A total of 452 children aged 6-9 y were included in this study. Appendicular skeletal muscle mass (ASM) was assessed by dual-energy X-ray absorptiometry. Hand grip strength was determined by the Jamar Plus+ hand dynamometer (Sammons Preston). Appendicular skeletal muscle mass index (ASMI) was calculated, and the relative concentrations of 20 fatty acids in erythrocyte membranes were measured by gas chromatography-mass spectrometry. Factor analysis was used to explore the relationship between fatty acids and skeletal muscle mass and grip strength. Five FAPs were identified by factor analysis, and after adjusting for covariates, a multiple linear regression model showed that FAP2 (high C17:0, C20:5 n-3, C22:6 n-3) showed a negative correlation with ASM (β = -0.214; P < 0.001), ASMI (β = -0.085; P < 0.001), and left-hand grip strength (β = -0.235; P = 0.012). FAP3 (high C14:0, C15:0, C16:0, C16:1 n-7, low C20:4 n-6) scores were positively correlated with ASM (β = 0.134, P = 0.017). No other associations between FAPs and skeletal muscle mass were found. The relationship between different FAPs and skeletal muscle health in children aged 6-9 y may be different. The pattern characterized by higher concentrations of C17:0, C20:5 n-3, and C22:6 n-3 in erythrocyte membranes may be associated with lower skeletal muscle mass. The pattern featuring higher concentrations of C14:0, C15:0, C16:0, and C16:1 n-7 and lower concentrations of C20:4 n-6 may be protective factors for muscle mass.

Reducing dietary crude protein levels while meeting metabolizable protein requirements: Performance of dairy cows over a full lactation period.

A total of 90 Holstein dairy cows (24 primiparous, 66 multiparous, mean parity = 3.0) were fed diets containing either 150, 160, or 170 g CP/kg DM from 8 to 180 DIM, with all diets designed to supply at least 100% MP requirements. On d 181, half of the cows in each treatment changed to a diet containing 140 g CP/kg DM (supplying 100% MP requirements), with the remaining cows continuing to be offered their original treatment diets. This resulted in 6 treatments in the mid-late lactation period (181-280 DIM): 150, 150/140, 160, 160/140, 170, and 170/140 g CP/kg DM. Decreasing dietary CP concentration from 170 to 150 g CP/kg DM did not affect DMI, milk yield, milk fat or protein yield in early lactation (8-181 DIM), but reduced MUN and the ratio of n-6 to n-3 fatty acids in milk, as well as serum albumin, globulin, total protein, and urea concentrations. In addition, reducing dietary CP content from 170 to 160 g CP/kg DM improved N use efficiency (NUE; milk N/N intake), with no further improvement with 150 g CP/kg DM. Treatment had no effect on apparent total-tract ration digestibility in early lactation. Urinary N output decreased with decreasing dietary CP content in early lactation, whereas manure N (fecal N plus urinary N) output increased. Urinary N/manure N decreased from 170 to 160 g CP/kg DM diet, whereas no further reduction was observed with the 150 g CP/kg DM diet. Cows that remained on the 150 g CP/kg DM treatment in mid-late lactation (181-280 DIM) had a lower DMI than those which remained on the diet containing 170 g CP/kg DM. Reducing the dietary CP concentration to 140 g CP/kg DM in mid-late lactation reduced DMI, milk yield, and milk fat and protein yields, compared with offering the 170 or 160 g CP/kg DM diet throughout lactation, possibly reflecting a response to oversupply of MP with the latter treatments, rather than an undersupply of MP with the former, although this is uncertain. Concentrations of C18:2 cis-9,trans-11 and the ratio of n-6 to n-3 fatty acids in milk were lower for cows offered diets containing 140 or 150 g CP/kg DM in mid-late lactation compared with 160 or 170 g CP/kg DM. Reducing dietary CP concentration from 170 to 140 g CP/kg DM improved NUE from 0.28 to 0.34 in mid-late lactation. Nitrogen digestibility was reduced when cows were offered the 140 g CP/kg DM diet compared with the 150 or 160 g CP/kg DM diet. Lowering the dietary CP concentration from 170 to 140 g CP/kg DM in mid-late lactation decreased N output in milk, feces, urine, and manure. These results indicate that a dietary CP content of 160 g CP/kg DM, which met the MP requirement of cows, may be optimal to support performance over a whole lactation, improve NUE, and reduce N excretion, thus contributing to a more sustainable approach to dairy cow production.

Effects of Coix seed polyphenol extract on rumen fermentation, milk production, fatty acid profile, antioxidant activity, and polyphenol content in dairy goats.

The transfer of natural antioxidants from feed to milk has become a research hotspot. Polyphenols are a source of potent natural antioxidants that may play important roles in improving antioxidant activity and milk quality in dairy goats. The aim of this study was to evaluate the effects of polyphenol-rich Coix seed extract (CSE) on rumen fermentation, milk production, fatty acid profile, antioxidant activity, and polyphenol content in milk from lactating dairy goats. Forty dairy goats were allocated to 4 treatments, and the treatments containing 0, 1.5, 3.0, or 4.5 g of CSE per kg of total mixed ration. The results indicated that the ruminal fluid total volatile fatty acid level increased linearly and quadratically, the acetic acid concentration and acetate:propionate ratio decreased quadratically, and the propionic acid level increased quadratically with increasing CSE concentration. An increase in dietary CSE linearly and quadratically increased milk production parameters, and quadratically increased milk protein, lactose, and solids-not-fat. The concentrations of C18:3n-3, C20:3n-3, and C22:5n-3 in milk were affected by the treatment, and increased quadratically, whereas those of C18:2n-6c, C20:3n-6, and C20:4n-6 decreased quadratically with increasing CSE. An increase in the concentration of CSE in the diet linearly and quadratically increased 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity in plasma and total antioxidant capacity (TAC) and catalase (CAT) activities in milk. The levels of gallic acid, protocatechuic acid, catechin, apigenin, kaempferol, and bergapten in milk were affected by the treatment, and linearly and quadratically increased with increasing dietary CSE levels. Significant positive correlations were detected between TAC, CAT, and DPPH scavenging activity and gallic acid, protocatechuic acid, apigenin, kaempferol, and bergapten, and positive correlations were detected between CAT and DPPH scavenging activity and catechin concentration in milk. In addition, significant positive correlations were detected between DPPH scavenging activity in plasma and TAC, DPPH scavenging activity in milk. Taken together, these findings indicate that dietary supplementation with CSE appears to be a promising strategy for improving the production performance of lactating dairy goats. Overall, the appropriate supplemental level of CSE was 1.5 g/kg in dairy goats under the conditions of the current experiment.

Effects of black soldier fly larvae oil on lipid metabolism, liver fatty acid composition, and plasma metabolite profiles in gilthead seabream juveniles.

The potential of insects as alternative ingredients in animal feeds is well-established. However, limited information is available on the use of insect oils as alternative lipid sources in aquafeeds. To address this, a study was conducted on gilthead seabream (Sparus aurata) juveniles to evaluate the effects of including black soldier fly (Hermetia illucens) larvae oil (HIO). Diets were formulated to include 4, 7.9, and 9.5 % HIO, replacing a vegetable oil blend at 42, 84, or 100 %, respectively. After 70 days, the effects on liver fatty acid profiles, plasma metabolites, and lipid metabolism gene expression were assessed. The results showed that HIO inclusion led to a linear decrease in plasma lipids and triglycerides, while high-density lipoprotein levels increased. The experimental diets also altered the liver's fatty acid composition without affecting total lipid content. There was an increase in the liver's saturated fatty acid content, like lauric acid, and monounsaturated FA, like oleic acid. In contrast, n-3 and n-6 polyunsaturated fatty acid content was reduced, although EPA and DHA levels remained unaffected. Additionally, the content of C16:0 and C18:0 (% of total fatty acids) was higher in the liver than in the corresponding diets. The inclusion of HIO had minimal impact on the expression of genes associated with fatty acid synthesis, transport, and β-oxidation. However, a downregulation of elongation of very long-chain fatty acids proteins 6 and 1b (elovl6 and elovl1b) was observed with increasing HIO levels. Overall, the study indicates that up to 9.5 % HIO inclusion in diets is well tolerated by gilthead seabream juveniles, with minimal effects on plasma metabolites and key gene expression related to fatty acid metabolism. These findings support the use of HIO as a viable alternative lipid source for juvenile gilthead seabream, contributing to the sustainable development of aquafeeds.

A Latent Cardiomyocyte Regeneration Potential in Human Heart Disease.

Cardiomyocytes in the adult human heart show a regenerative capacity, with an annual renewal rate of ≈0.5%. Whether this regenerative capacity of human cardiomyocytes is employed in heart failure has been controversial. We determined cardiomyocyte renewal in 52 patients with advanced heart failure, 28 of whom received left ventricular assist device support. We measured the concentration of nuclear bomb test-derived 14C in cardiomyocyte genomic DNA and performed mathematical modeling to establish cardiomyocyte renewal in heart failure with and without LVAD unloading. We show that cardiomyocyte generation is minimal in end-stage heart failure patients at rates 18 to 50× lower compared with the healthy heart. However, patients receiving left ventricle support device therapy, who showed significant functional and structural cardiac improvement, had a >6-fold increase in cardiomyocyte renewal relative to the healthy heart. Our findings reveal a substantial cardiomyocyte regeneration potential in human heart disease, which could be exploited therapeutically.

Radiocarbon in aquatic biota samples in a brackish lake adjacent to a reprocessing plant in Rokkasho, Japan, from 2006 to 2022.

The commercial spent-nuclear-fuel reprocessing plant in Rokkasho, Japan, is scheduled for completion in 2024. Its fuel rods were cut into segments and chemically processed between 2006 and 2008, as part of the plant's test operations. During the test, 14C (4.4 TBq) were discharged from the plant's main stack into the atmosphere. At reprocessing plants, 14C has the largest contribution to the effective dose to the public among the nuclides released into the atmosphere, and it important to understand the concentration distribution and impact of 14C in the surrounding environment. This study conducts a continuous monitoring of 14C in aquatic biota samples around the plant from 2006 to 2022. The 14C concentration in most samples was determined at the background level, and the effect of the plant was slightly recognized in some samples. Moreover, the specific radioactivity of 14C decreased faster than the theoretical decay from 0.242 to 0.225Bq-g C-1.

Improving the method for calculating carbon emissions from waste incineration: confirmed with carbon-14 testing of flue gas

An improved method was developed to calculate direct emissions from seven municipal solid waste incineration plants by adjusting the physical compositions of waste by invoking the proportion of co-incinerated waste and the bottom ash yield. The fossil carbon fractions of the waste components were determined by carbon-14 (14C) testing. Based on the improved method, direct emissions were in the range of 222–610 kg CO2-eq/t waste, corresponding to reductions of 3.4–221 kg CO2-eq/t waste compared with the method without waste composition adjustment. The 14C contents of the flue gas before and after gas cleaning were tested to validate the improved method, and indicated fossil CO2 emissions of 249–446 and 233–405 kg CO2-eq/t waste, respectively. The direct emissions obtained by the improved method were closer to the results of 14C testing, due to more accurate estimations of the actual waste composition. The method was further combined with a life cycle analysis of the waste incineration process, obtaining total carbon emissions in the range from –33.2 to 483 kg CO2-eq/t waste. The findings provide a new means of accurately calculating carbon emissions from waste incineration.Graphical

Optically Detectable Magnetic Resonance of NV-Center Ensembles in CVD Diamond with Different 13C Contents

Optically Detectable Magnetic Resonance of NV-Center Ensembles in CVD Diamond with Different 13C Contents

Bound phenolics extracts of jujube peel relieve cadmium-induced toxicity by reducing lipid accumulation of Caenorhabditis elegans.

To investigate the effect of bound phenolics extracts (BPEs) of jujube peel on relieving cadmium (Cd)-induced toxicity and its mechanism, the behavioral deficits, lipid accumulation, and fatty acid synthesis-related gene expression in Caenorhabditis elegans in Cd exposure group and BPEs improvement groups were determined and compared. The results showed that BPEs significantly improved Cd-induced behavioral deficits in C. elegans, and no significant differences could be found in low-dose (12.5µg/mL) and high-dose (100µg/mL) BPEs improvement groups. The treatment of BPEs effectively improved intestinal injury and lipofuscin and lipid accumulation. Especially, oil red O staining intensity in C. elegans treated with BPEs at 50µg/mL was reduced by 12.60%. BPEs significantly controlled the increase in content of C16:0, C16:1, C18:0, C18:1, and C18:2 induced by Cd by regulating the lipid accumulation in Escherichia coli OP50. Cd exposure induced lipid accumulation in C. elegans by upregulating oleic acid synthesis-related gene expression in E. coli OP50. Furthermore, BPEs treatment significantly downregulated the fatty acid synthesis-related gene expression in C. elegans and E. coli OP50. This research could reveal the mechanism of BPEs of jujube peel in relieving Cd-induced toxicity and provide a theoretical basis for the development of functional foods rich in polyphenols. PRACTICAL APPLICATION: Jujube peel, a by-product of jujube processing, is usually discarded due to its coarse texture. However, jujube peel has been proven to possess abundant polyphenols, polysaccharides, and cyclic adenosine phosphate. In addition, in our previous research, bound phenolics extracts (BPEs) of jujube peel were found to perform better in lowering lipid accumulation than that of free phenolics extracts. This study further investigate the effect of BPEs of jujube peel on relieving Cd-induced toxicity and its mechanism on the base of our previous research. It could realize the comprehensive utilization of by-products of jujube processing.

Feedbacks From Young Permafrost Carbon Remobilization to the Deglacial Methane Rise

AbstractThe abrupt warming events punctuating the Termination 1 (about 11.7–18 ka Before Present, BP) were marked by sharp rises in the concentration of atmospheric methane (CH4). The role of permafrost organic carbon (OC) in these rises is still debated, with studies based on top‐down measurements of radiocarbon (14C) content of CH4 trapped in ice cores suggesting minimum contributions from old and strongly 14C‐depleted permafrost OC. However, organic matter from permafrost can exhibit a continuum of 14C ages (contemporaneous to &gt;50 ky). Here, we investigate the large‐scale permafrost remobilization at the Younger Dryas‐Preboreal transition (ca. 11.6 ka BP) using the sedimentary record deposited at the Lena River paleo‐outlet (Arctic Ocean) to reflect permafrost destabilization in this vast drainage basin. Terrestrial OC was isolated from sediments and characterized geochemically measuring δ13C, Δ14C, and lignin phenol molecular fossils. Results indicate massive remobilization of relatively young (about 2,600 years) permafrost OC from inland Siberia after abrupt warming triggered severe active layer deepening. Methane emissions from this young fraction of permafrost OC contributed to the deglacial CH4 rise. This study stresses that underestimating permafrost complexities may affect our comprehension of the deglacial permafrost OC‐climate feedback and helps understand how modern permafrost systems may react to rapid warming events, including enhanced CH4 emissions that would amplify anthropogenic climate change.

ORIGIN AND AGE OF CARBON IN THE CELLULOSE OF MID-LATITUDE TREE RINGS

ABSTRACT Cellulose of tree rings is often assumed to be predominantly formed by direct assimilation of CO2 by photosynthesis and consequently can be used to reconstruct past atmospheric 14C concentrations at annual resolution. Yet little is known about the extent and the age of stored carbon from previous years used in addition to the direct assimilation in tree rings. Here, we studied 14C in earlywood and latewood cellulose of four different species (oak, pine, larch and spruce), which are commonly used for radiocarbon calibration and dating. These trees were still growing during the radiocarbon bomb peak period (1958–1972). We compared cellulose 14C measured in tree-ring subdivisions with the atmospheric 14C corresponding to the time of ring formation. We observed that cellulose 14C carried up to about 50% of the atmospheric 14C signal from the previous 1–2 years only in the earlywood of oak, whereas in conifers it was up to 20% in the earlywood and in the case of spruce also in the latewood. The bias in using the full ring of trees growing in a temperate oceanic climate to estimate atmospheric 14C concentration might be minimal considering that earlywood has a low mass contribution and that the variability in atmospheric 14C over a few years is usually less than 3‰.

Plasma ceramides as biomarkers for microvascular disease and clinical outcomes in diabetes and myocardial infarction

BackgroundCeramides have recently been identified as novel biomarkers associated with diabetes mellitus (DM) and major adverse cardiac and cerebrovascular events (MACCE). This study aims to explore their utility in diagnosing microvascular disease.MethodsThis study prospectively enrolled 309 patients from 2018 to 2020 into three groups: healthy controls (Group 1, N = 51), DM patients without acute myocardial infarction (AMI) (Group 2, N = 150), and DM patients with AMI (Group 3, N = 108). We assessed outcomes using stress perfusion cardiac magnetic resonance (CMR) imaging for coronary microvascular disease (CMD) (Outcome 1), retinography for retinal microvascular disease (RMD) (Outcome 2), both CMD and RMD (Outcome 3), and absence of microvascular disease (w/o MD) (outcome 4). We evaluated the classification performance of ceramides using receiver operating characteristic (ROC) analysis and multiple logistic regression. 11-ceramide panel previously identified by our research group as related to macrovascular disease were used.ResultsAverage glycated hemoglobin (HbA1c) values were 5.1% in Group 1, 8.3% in Group 2, and 7.6% in Group 3. Within the cohort, CMD was present in 59.5% of patients, RMD in 25.8%, both CMD and RMD in 18.8%, and w/o MD in 38.5%. The AUC values for the reference ceramide ratios were as follows: CMD at 0.66 (p = 0.012), RMD at 0.61 (p = 0.248), CMD & RMD at 0.64 (p = 0.282), and w/o MD at 0.67 (p = 0.010). In contrast, the AUC values using 11-ceramide panel showed significant improvement in the outcomes prediction: CMD at 0.81 (p = 0.001), RMD at 0.73 (p = 0.010), CMD & RMD at 0.73 (p = 0.04), and w/o MD at 0.83 (p = 0.010). Additionally, the plasma concentration of C14.0 was notably higher in the w/o MD group (p < 0.001).ConclusionsPlasma ceramides serve as potential predictors for health status and microvascular disease phenotypes in diabetic patients.

Traveling Light: Arctic Coastal Erosion Releases Mostly Matrix Free, Unprotected Organic Carbon

AbstractThe Arctic rapidly warms and sea ice retreats, a large fraction of organic carbon (OC), currently stored in coastal permafrost will be released into the marine system. Once reintroduced into the active carbon cycle, this material will either be decomposed or buried on the shelf depending on its hydrodynamic and chemical properties. Currently, carbon estimates are based on bulk measurements, which does not take the hydrodynamic pathway of different fractions into account. Therefore, eight coastal permafrost locations have been sampled along the Canadian Beaufort Sea Coast, hydrodynamically fractionated and analyzed for their C, N, 13C and 14C content. We found that the matrix‐free fraction (low density &lt;1.8 g/cm3, and high‐density &gt;1.8 g/cm3; &lt;38 μm) account for 77%–98% of the OC. By using a coastal classification combined with field data, our results showed that short coastal segments can become key players in delivering matrix‐free, easily degradable OC to the marine system.

Strontium isotopes in the atmosphere, geosphere and hydrosphere: Developing a systematic “fingerprinting” framework of rocks and water in sedimentary basins in eastern Australia

Understanding the connection between aquifers, aquitards, and groundwater-dependant ecosystems remains a key challenge when developing a conceptual hydrogeological model. The aim of this study was to develop a systematic strontium isotope (87Sr/86Sr) fingerprinting framework of rocks and water within the sedimentary Surat and Clarence-Moreton basins (SCM basins) in eastern Australia – an area of extensive coal seam gas development and high potential for aquifer and groundwater-surface water connectivity. To do this, new groundwater samples (n = 298) were collected, analyzed and integrated with published data (n = 154) from the basins' major sedimentary, volcanic and alluvial aquifers, including the major coal seam gas target, the Walloon Coal Measures. Samples were also analyzed from rainfall (n = 2) and surface water (n = 40). In addition, rock core samples (n = 39) from exploration and stratigraphic wells were analyzed to determine the range of Sr isotope composition from host rocks. The analyses of cores demonstrate a distinct and systematic contrast in 87Sr/86Sr between different hydrogeological units. This confirms that all major hydrogeological units have a narrow range with unique 87Sr/86Sr population characteristics that are useful for guiding conceptual model development. Comparison with selected hydrochemical and groundwater age tracers (14C and 36Cl) suggests only limited changes of 87Sr/86Sr from recharge beds to the deeper parts of the basins or with a decrease in natural 14C and 36Cl tracer content along flow paths. Stream sampling during baseflow conditions confirms that 87Sr/86Sr in surface waters are similar to those of the underlying bedrock formations. We demonstrated that 87Sr/86Sr analyses of rocks and water provide a powerful hydrostratigraphic and chemostratigraphic fingerprinting framework in the SCM basins, enabling reliable assessments of plausible aquifer and groundwater-surface water interconnectivity pathways. Applied in other complex multi-aquifer sedimentary basins in Australia, and globally, a similar approach can help to constrain conceptual hydrogeological models and facilitate improved water resource management.

Radiocarbon analysis reveals underestimation of soil organic carbon persistence in new-generation soil models

Abstract. Reflecting recent advances in our understanding of soil organic carbon (SOC) turnover and persistence, a new generation of models increasingly makes the distinction between the more labile soil particulate organic matter (POM) and the more persistent mineral-associated organic matter (MAOM). Unlike the typically poorly defined conceptual pools of traditional SOC models, the POM and MAOM soil fractions can be directly measured for their carbon content and isotopic composition, allowing for fraction-specific data assimilation. However, the new-generation model predictions of POM and MAOM dynamics have not yet been validated with fraction-specific carbon and 14C observations. In this study, we evaluate five influential and actively developed new-generation models (CORPSE, MEND, Millennial, MIMICS, SOMic) with fraction-specific and bulk soil 14C measurements of 77 mineral topsoil profiles in the International Soil Radiocarbon Database (ISRaD). We find that all five models consistently overestimate the 14C content (Δ14C) of POM by 69 ‰ on average, and two out of the five models also strongly overestimate the Δ14C of MAOM by more than 80 ‰ on average, indicating that the models generally overestimate the turnover rates of SOC and do not adequately represent the long-term stabilization of carbon in soils. These results call for more widespread usage of fraction-specific carbon and 14C measurements for parameter calibration and may even suggest that some new-generation models might need to restructure or further subdivide their simulated carbon pools in order to accurately reproduce SOC dynamics.