Cumulative Flux Research Articles

Nitrous oxide emissions and yields from potato production systems as influenced by nitrogen fertilization and irrigation: A meta‐analysis

AbstractPotato (Solanum tuberosom) is a globally significant crop in relation to the scale of its consumption, being the third most consumed worldwide. The overall sustainability of global agriculture is increasingly of concern, specifically in relation to increasing anthropogenic emissions of the greenhouse gas nitrous oxide (N2O) emissions from nitrogen fertilizer additions to croplands and its contribution to climate change. Against this backdrop, a meta‐analysis of 119 experimental comparisons from 18 studies—spanning 19 study sites in 10 countries—was employed to investigate the impact of irrigation, cumulative water input, N fertilizer application rate, soil pH, and soil texture on cumulative N2O fluxes and tuber yield in potato production. Compared to non‐fertilized controls, N2O emissions from fertilized potato production decreased by 34% when irrigation provided 61%–90% of total water input (corresponding to averages of 321–473 mm). Likewise, N2O emissions increased by 53% with 200–475 mm seasonal water input and by 37% with N fertilization rates of 101–200 kg N fertilizer ha−1. Furthermore, soil pH between 7.1 and 7.5 reduced emissions by 6%, while medium‐textured soils showed an increase of 2%. Conversely, tuber yields from fertilized potato production were comparatively maximized under 31%–60% of water input as irrigation (7%) and 751–1025 mm cumulative seasonal water input (28%). Alongside 201–300 kg N fertilizer ha−1 (97%), soil pH of 7.1–7.5 (48%), and in coarse‐textured soils (49%). Overall, these findings underscore the importance of considering irrigation and N fertilization options specifically in optimizing potato production for reduced N2O emissions and enhanced tuber yield.

Coastal <i>Synechococcus</i> strains can exploit low oxygen habitats

We found that PhycoErythrin-rich <i>Synechococcus</i> achieved faster growth rates (µ), across the spectral bandwidths from 405 – 730 nm, under 2.5 µM [O<sub>2</sub>], characteristic of Oxygen Minimum Zones (OMZs), than under 250 µM [O<sub>2</sub>], whereas PhycoCyanin-rich strain showed generally similar µ under 2.5 and 250 µM [O<sub>2</sub>]. For PhycoCyanin- and PhycoErythrin-rich <i>Synechococcus</i>, µ showed also positive linear responses to both Phycobiliproteins:Chlorophyll <i>a</i>, and to cumulative diel PSII electron flux, although the relations vary across strain and [O<sub>2</sub>]. Electron transport downstream of Photosystem II was generally higher for both PhycoCyanin- and PhycoErythrin-rich strains under 250 µM [O<sub>2</sub>], since cyanobacteria show strong capacity for electron flow away from PSII to O<sub>2</sub>, particularly under excess excitation. Even though electron transport was faster under 250 µM [O<sub>2</sub>], the PhycoErythrin-rich strain showed a higher growth yield of electron transport under 2.5 µM [O<sub>2</sub>]. PhycoErythrin-rich <i>Synechococcus</i> are currently typically found at greater depths, and lower light, than are PhycoCyanin-rich strains, but we suggest that the PhycoErythrin-rich strains are actually limited to lower light by an interaction between light and full air-saturated [O<sub>2</sub>]. In expanding Oxygen Minimum Zones PhycoErythrin-rich strains will likely exploit higher light niches, across a wider spectral range.

Impact of Skin Decontamination Wipe Solutions on the Percutaneous Absorption of Polycyclic Aromatic Hydrocarbons.

Firefighter occupational exposures were categorized as a class 1 (known) carcinogen by the International Agency for Research on Cancer in 2022. As a result, firefighters have become heavily focused on identifying effective and easy to implement decontamination strategies to reduce their chemical exposures. Skin decontamination using wipes post-exposure is one decontamination strategy that every firefighter has available to them. However, firefighters have expressed concerns over the ingredients in the wipe solution increasing dermal absorption. The goal of this study was to determine if the ingredients in skin decontamination wipe solution had any enhancement effect on the dermal absorption of phenanthrene. To determine any enhancement effects, the additive solution of four skin decontamination wipe products was applied to porcine skin 15 min after chemical dosing. The absorption of phenanthrene was tested in vitro using a flow-through diffusion cell system over eight hours. The wipe solution effects on dermal absorption were determined by measuring multiple absorption characteristics including cumulative absorption (µg/cm2), absorption efficiency (% dose absorbed), lag time (minutes), flux (µg/cm2/h), diffusivity (cm2/h), and permeability (cm/h). No penetration enhancement effects were observed in any of the skin decontamination wipe solutions tested; rather, all wipe solutions decreased the absorption of phenanthrene. Slight differences in cumulative absorption among two pairings of skin decontamination wipe solutions, wipes 1 and 3 vs. wipes 2 and 4, were observed, indicating that some ingredients may impact dermal absorption. These findings show that firefighters should continue using skin decontamination wipes to reduce their dermal exposures to fireground contaminants with little concern of increasing the absorption of phenanthrene.

Warming events and their causes at the Bering Sea section B in summer of 1999–2019

Based on hydrological data for the Bering Sea from 1999 to 2019 during the Chinese National Arctic Research Expeditions (CHINAREs), along with oceanographic and meteorological data from the National Centers for Environmental Information (NCEI) and the European Centre for Medium-Range Weather Forecasts (ECMWF), we investigated trends in summer at the Bering Sea section B over the past 20 years and their underlying causes. The results revealed a pronounced rise in temperature at the Bering Sea section B in 2003, 2014, 2016, 2018, and 2019, suggesting a shift towards a new phase of warmth starting in 2014. In warm years (2003, 2014, 2016, 2018, and 2019), the mean maximum temperature in the upper layer in the basin north of 57°N and on the continental shelf were roughly 2.7 °C, 2.6 °C higher than that in cold years (1999, 2008, 2010, and 2012). Additionally, the mean minimum temperature of the cold water in the middle layer in the basin was roughly 0.7 °C higher in the warm years compared to the cold years. This difference between the warm and cold years was evident in the heat content: the average heat content in the upper to middle layers in the basin north of 57°N and on the continental shelf were about 1.2 and 0.9 GJ/m2 higher, respectively, in the warm years than the cold years. However, there was a modest warming trend in the basin south of 57°N, and the temperature in the mid-layer on the continental shelf showed year-to-year stability, in contrast to the significant warming observed elsewhere. Further study suggested that temperature fluctuation in the basin was closely tied to seasonal 2-m air temperature. In addition, the southern basin, divided at 57°N, experienced larger positive or negative anomalous wind stress curl compared to the northern basin. This discrepancy resulted in differing causes of temperature variation between the two regions. Temperature change in the upper layer on the continental shelf was attributed to an increase in cumulative net heat flux resulting from reduced sea ice, while the temperature in the middle layer on the continental shelf was limited by the enhanced density gradient between the upper and middle layer caused by melt ice, preventing significant warming. Overall, the thermal state for the Bering Sea section B was influenced by a combination of factors, including net heat flux, sea ice, and atmospheric conditions, contributing to the year-to-year variation characterized by alternating cold and warm regimes.

Effect of dairy manure‐based fertilizers on nitrous oxide emissions in a semi‐arid climate

AbstractManure treatment technologies are of interest to dairy operations to improve nutrient management, although there are little data related to nutrient availability and environmental impacts of these manure‐based fertilizer products. This field trial experiment investigated the impact of two manure‐based fertilizer sources (phosphorus enriched solids [PE] and mechanical vapor recompression solids [VR]) on soil nutrients, crop yields, and N2O emissions in a forage rotation. The study was a factorial random complete block design, with two main factors: manure history (with [M]; without [NM]) and manure‐based fertilizer product (control [Con], PE, VR), under a continuous corn and triticale rotation. M had greater soil organic carbon, total carbon, total nitrogen, and M3‐P (30%–128%) and reduced NH4‐N (15%) than NM, with no other treatment differences. Corn silage yields were greater in NM versus M (7%) treatments only in 2021, while in 2022 VRNM was 17% greater than ConNM only. Triticale yields were 14% greater in M plots versus NM treatments only in 2021. In 2022, triticale yields were 1.7 times lower in ConNM versus all other treatments, and PENM was 71% greater than ConM. The greatest N2O fluxes occurred in May, June, and July with M having 69% greater average cumulative fluxes than NM, while average VR cumulative fluxes were 102% greater than PE and Con. Over both years, net loss of Napplied as N2O‐N was 1.9%–2.2% for VR and 0.4%–0.8% for PE solids. While manure‐based fertilizers performed well as a nutrient source, their susceptibility to N2O loss needs to be considered in management strategies.

An innovative soil mesocosm system for studying the effect of soil moisture and background NO on soil surface C and N trace gas fluxes

Nitric oxide (NO) is a key substance in atmospheric chemistry, influencing the formation and destruction of tropospheric ozone and the atmosphere's oxidizing capacity. It also affects the physiological functions of organisms. NO is produced, consumed, and emitted by soils, the effects of soil NO concentrations on microbial C and N cycling and associated trace gas fluxes remain largely unclear. This study describes a new automated 12-chamber soil mesocosm system that dynamically changes incoming airflow composition. It was used to investigate how varying NO concentrations affect soil microbial C and N cycling and associated trace gas fluxes under different moisture conditions (30% and 50% WFPS). Based on detection limits for NO, NO2, N2O, and CH4 fluxes of < 0.5 µg N or C m−2 h−1 and for CO2 fluxes of < 1.2 mg C m−2 h−1, we found that soil CO2, CH4, NO, NO2, and N2O were significantly affected by different soil moisture levels. After 17 days cumulative fluxes at 50% WFPS increased by 40, 400, and 500% for CO2, N2O, and CH4, respectively, when compared to 30% WFPS. However, cumulative fluxes for NO, and NO2, decreased by 70, and 40%, respectively, at 50% WFPS when compared to 30% WFPS. Different NO concentrations tended to decrease soil C and N fluxes by about 10–20%. However, with the observed variability among individual soil mesocosms and minor fluxes change. In conclusion, the developed system effectively investigates how and to what extent soil NO concentrations affect soil processes and potential plant–microbe interactions in the rhizosphere.

Greenhouse gas emissions in response to tillage, nitrogen fertilization, and manure application in the tropics

Cultivation of maize (Zea mays L.) can emit significant greenhouse gases (GHGs) due to root respiration, soil organic matter decomposition, and fertilizer losses in a tropical environment. Our objective was to examine the effect of tillage (conventional tillage [CT], minimum tillage [MT], and no-tillage [NT]), N fertilization rate (0, 90, and 120 kg N ha−1), and manure application rate (0, 5, and 10 Mg ha−1) on CO2, N2O, and CH4 emissions under maize in two growing seasons (July-October 2018 and May-August 2019) in southwest Nigeria. We measured CO2, N2O, and CH4 fluxes using the static chamber method and soil temperature and water content weekly, global warming potential (GWP), maize yield, and greenhouse gas intensity (GHGI). The CO2 and N2O fluxes peaked immediately following planting, fertilization, and intense precipitation, with most fluxes concentrated at 2–6 wk after planting. The CH4 flux showed little change throughout the duration of the study. Cumulative CO2 and N2O fluxes were greater for CT and MT than NT, but cumulative CH4 flux was greater for MT than CT and NT. Higher N fertilization rate increased N2O and CH4 fluxes. The GWP was greater for CT than MT and NT and greater for 90 than 0 kg N ha−1. Maize yield was greater for MT than CT and NT and increased with higher N fertilization rate. The GHGI was lower for MT than CT and lower for 120 than 0 and 90 kg N ha−1. Because of overall lower maize yield, MT with reduced N ferilization rate in split applications may be needed to reduce GHG emissions while sustaining yield in the sandy soils of southwest Nigeria.

Co-accumulation characteristics and interaction mechanism of microplastics and PFASs in a large shallow lake

Microplastics (MPs) and per- and polyfluoroalkyl substances (PFASs) coexist widely in lakes and affect ecological security. The coexistence characteristics and adsorption-desorption mechanisms between MPs and typical PFASs were explored in a typical eutrophic shallow lake (Taihu Lake). Polyvinyl chloride (PVC) and polyethylene (PE) are the primary types of MPs in Taihu Lake, with average abundances in water and sediment of 18630 n/m3 and 584 n/kg, respectively. The average concentrations of PFASs in water and sediment are 288.93 ng/L and 4.33 ng/g, with short-chain PFASs (C4-C7) being the main pollutants. Perfluorobutanoic acid (PFBA) in both water and sediment contributed 38.48 % and 44.53 %, respectively, followed by hexafluoropropylene oxide dimer acid (HFPO-DA). The morphological characteristics of MPs influence the distribution of long-chain PFAS in lake water, while the presence of HFPO-DA and perfluorohexanoic acid (PFHxA) in sediment is directly linked to the concentration and size of MPs. A combination of field investigations and indoor experiments revealed that the irreversible adsorption characteristics between MPs and HFPO-DA may promote the high cumulative flux of HFPO-DA in sediment, and the biofilm on the surface of MPs significantly accelerates this accumulation process. The results provide a new perspective on the co-transport behavior of emerging pollutants in aquatic environments.

Duration, not timing during the photoperiod, of far-red application determines the yield increase in tomato

Supplementary far-red light may increase fruit yield in greenhouse tomato cultivation. Apart from end-of-day applications, research has focussed on the effects of far-red light during the entire photoperiod, while few studies focused on the timing of far-red application. In this study, we assessed the impact of timing and duration of far-red application on fruit yield and quality in a high-wire tomato crop. Two commercial tomato cultivars were grown under 226 μmol m−2 s−1 of red and white supplementary LED lighting. Far-red light (63 μmol m−2 s−1) was additionally supplied during either the first or the second half of the photoperiod. These treatments were compared to a negative control, where no far-red light was supplied, and a positive control, where far-red light was supplied during the whole photoperiod. A yield component analysis was conducted to identify the parameters responsible for changes in fruit yield. We determined that fruit yield, total fruit dry weight and fruit production per unit of supplementary PAR light (400–700 nm) increased linearly with the duration of far-red application. Fruit yield was increased to a similar extent whether far-red was supplemented in the first or in the second half of the photoperiod. While different light treatments included 0, 14, or 28 % far-red in their cumulative supplementary photon flux density, there were no significant differences in their fruit production per unit of supplementary radiation (400–800 nm). Supplementary far-red increased fruit dry weight per unit of cultivation area by 23 % to 25 % as a result of increasing both plant dry weight (10 % to 12 %) and dry weight partitioning to the fruits (10 % to 14 %). The increase in fruit yield was less than the corresponding increase in total fruit dry weight due to a simultaneous increase in fruit dry matter content. Total soluble solids and pH of the fruits were hardly affected by far-red application. We concluded that supplementary far-red increased tomato fruit yield without compromising fruit quality, with this increase being determined by the duration of far-red application, not by its timing during the photoperiod.

Artificial neural network based model to predict mega cusp characteristics in Hasaki, Japan

Cusps, characterized by a series of horns and embayments, are notable coastal features observed along shorelines in various areas. When the horn-to-horn distances of cusps are substantial, they are referred to as mega cusps. There is a scarcity of measured morphological data for mega cusps, especially long-term data, making it challenging to acquire comprehensive insights. In this study, the morphodynamic characteristics of mega cusps such as mega cusp cross-shore extent and length were analyzed using data collected from Hasaki Beach in Japan over the period of 2007 to 2020. The analysis aimed to address the lack of accurate formulation and numerical models for simulating mega cusp morphological characteristics, which poses another obstacle in mega cusp prediction. To overcome this, different Artificial Neural Networks (ANNs) were employed to predict the horn-to-horn and horn-to-embayment distances of mega cusps following storm events. Storm wave parameters, including significant wave height, wave period, and wave direction, along with additional data such as cumulative energy flux and storm event duration, were utilized as input variables for the ANNs. The accuracy of the predicted results was assessed using the Pearson correlation coefficient, which was calculated based on a comparison with field data. The findings of this study demonstrated that the inclusion of significant wave height, wave period, wave direction, cumulative energy flux, and storm duration in the ANNs yielded satisfactory accuracy in predicting mega cusp characteristics. Overall, this investigation contributes to advancing our understanding of beach mega cusp dynamics and offers a viable approach for predicting mega cusp characteristics by utilizing artificial neural networks and incorporating relevant storm wave parameters.

Precipitation Patterns, Mountaintop Removal Mining, and the July 2022 North Fork Kentucky River Flood

ABSTRACT Heavy rain over eastern Kentucky during late July 2022 caused catastrophic flooding along the North Fork Kentucky River. A disproportionate number of the 45 deaths attributed to the flood occurred along or near Troublesome Creek, a tributary that has had 25 percent of its watershed affected by mountaintop removal coal mining over the last 40 years. Flood recurrence intervals at gages along the North Fork ranged from 94 years at Jackson to 2 years upstream at Hazard to 850–1,000 years farthest upstream at Whitesburg. The recurrence interval variability is consistent with the spatial distribution of rainfall during the event, which varied by a factor of 3 over the watershed upstream from Jackson. A topographically driven cumulative flux model based upon a cumulative precipitation map, a lidar digital elevation model, and absorption coefficients calibrated to streamflow and precipitation data show that Troublesome Creek contributed 35 percent of the cumulative discharge of the North Fork at the confluence from 28 percent of the upstream watershed area. Comparison of the calibrated model to a hypothetical model that assumes no mining-related reduction in absorption suggests the maximum increase in cumulative stream discharge during the flood potentially attributable to mountaintop removal mining is 22 percent along the North Fork at Whitesburg, 28 percent along the North Fork at Jackson, 41 percent along Troublesome Creek at its confluence with the North Fork, greater than 50 percent upstream along reaches adjacent to mined areas, and 50 to 150 percent in small tributaries emanating from mined areas.

Nitrous oxide fluxes during a winter cover crop season in a Mississippi corn cropping system

Agroecosystems are the largest source of anthropogenic N2O fluxes. While cover crops (CC) offer benefits for soil health, their impacts on greenhouse gas fluxes are inconsistent. In the southeastern US, where intensive agriculture and low CC adoption are prevalent, few studies have investigated CC impact on soil N2O fluxes. Our study explored the effects of CC species and management practices on soil N2O fluxes during the winter CC growing season in Mississippi, which was conducted in a non-tilled corn cropping system with seven CC treatments. We measured in situ soil N2O fluxes, along with soil moisture and temperature, throughout the CC growing season from 2022 to 2023. Surface soil samples were also collected to analyze soil mineral nitrogen (N) content and enzyme activity. Over the study period (a total of 188 days), cumulative N2O fluxes were 0.50–1.03 ​kg N2O–N ha−1, with the lowest values from the annually-rotated Elbon rye treatment and the highest from the annually-rotated Austrian winter pea. Our results show that both CC treatments and sampling time significantly affected soil N2O fluxes. There was a strong positive correlation (r ​= ​0.34, p ​< ​0.05) between N2O fluxes and NO3–N content, which was lowest under continuous rye and rotated-rye treatments (0.31 and 0.34 ​mg ​kg−1 ). The results suggest that Elbon rye effectively reduced soil N2O fluxes during this period by lowering the soil NO3–N content, the primary substrate for denitrification. This study is one of the few studies to examine the impacts of cover crops on soil N2O fluxes in cropping systems in the southeastern US, offering insights into the cover crop effects on soil N2O fluxes during their growing season.

Eddy covariance fluxes of greenhouse gasses observed in a renewed pasture in the southeast of Brazil

The recovery of degraded pastures and the increase in their capacity for storing carbon is a key strategy in Brazil's commitment to meeting its Nationally Determined Contribution (NDC) to the international effort to halt global warming. Here we report the fluxes of CO2, N2O and CH4 gasses and their balances, obtained by the eddy covariance method, from a representative pasture area in southeast Brazil. The measurements covered more than five years, starting with the old degraded pasture, covering the renewal process and then the re-establishment of pasture. The latter only received nitrogen fertilization once after the renewal – the common practice. The net ecosystem carbon balance (NECB), which considered the sum of the net ecosystem exchange (NEEpasture) of CO2 and methane (FCH4pasture) without the cattle respiration and enteric fermentation, as well the export/import of carbon by grazing and as feces (stocking rates of 1.8 to 3.3 AU ha−1), was positive in the old pasture (236 ± 104 g CO2m−2 year−1) representing a source to the atmosphere, but a sink (negative) during the first year of the renewal (-1603 ± 122 g CO2m−2 year−1) when it was fertilized and the recorded rainfall was normal. In the following two years it was neutral (77 ± 93 and 5 ± 100 g CO2m−2 year−1), partially a consequence of the lower rainfall received. In the fourth year it was a sink again (-736 ± 131 g CO2m−2 year−1). On average the cumulative fluxes of CH4 (42 ± 19 g CO2 eq. m−2 year−1) without the animals’ enteric fermentation and N2O (20 ± 10 g CO2 eq. m−2 year−1) were small and positive, being offset by the net carbon gain. The NECB for this site covering the period of measurements was an overall source of 671 ± 254 g CO2m−2.

Effect of agricultural management system (“cash crop”, “livestock” and “climate optimized”) on nitrous oxide and ammonia emissions

AbstractThe study aimed to measure soil-atmosphere N2O fluxes and their controlling factors, as well as NH3 emissions and yields for two soils (silt loam and clay loam) in three management systems over two years under subsequent wheat and maize cultivation. The management systems were characterized as follows: (1) cash crop (C) with mineral fertilizer and conventional tillage; (2) livestock (L) with biogas residue fertilization and its incorporation prior to sowing in maize and reduced tillage; and (3) climate optimized (O) with minimum tillage, 8-year crop rotation, with biogas residue fertilization, in maize without incorporation in clay loam soil or incorporation by strip-tillage prior to seeding in silt loam soil. Stable isotope ratios of N2O and mineral N were determined to identify N2O processes. Within the organically fertilized maize treatments, cumulative N2O fluxes were highest in the O-system treatments of both sites (4.0 to 9.4 kg N ha− 1 a− 1), i.e. more than twice as high as in the L-system (1.5 to 3.1 kg N ha− 1 a− 1). Below root-strip till fertilizer application did not enhance N2O fluxes. Fluxes with mineral fertilization of wheat (1.1 to 3.1 kg N ha− 1 a− 1) were not different from those with organic fertilization. Isotopic values of emitted N2O revealed that bacterial denitrification dominated most of the peak flux events, while the N2O/(N2 + N2O) ratio of denitrification was mostly between 0.1 and 0.5. It can be concluded that, contrary to the intention to lower greenhouse gas fluxes by the O-system management, the highest N2O fluxes occurred in the O-system without biogas digestate incorporation in maize. With respect to NH3 fluxes, we could confirm that the application of digestate application in growing crops without incorporation or late incorporation in fertilization before sowing induces high fluxes. The beneficial aspects of the O-system including more stable soil structure and resource conservation, are thus potentially counteracted by increased N2O and NH3 emissions.

Helium in Exoplanet Exospheres: Orbital and Stellar Influences

Searches for helium in the exospheres of exoplanets via the metastable near-infrared triplet have yielded 17 detections and 40 nondetections. We performed a comprehensive reanalysis of published studies to investigate the influence of stellar X-ray and extreme-ultraviolet (XUV) flux and orbital parameters on the detectability of helium in exoplanetary atmospheres. We identified a distinct “orbital sweet spot” for helium detection, 0.03 to 0.08 au from the host star, where the majority of detections occurred. This sweet spot is influenced by the stellar luminosity and planet size. Notably, a lower ratio of XUV flux to mid-UV flux is preferred for planets compared to nondetections. We also found that helium detections occur for planets around stars with effective temperatures of 4400–6500 K (i.e., spectral type K and G stars), with a sharp gap between 5400 and 6000 K, where no detections occur. We also report an upper-limit efficiency of 6% for energy-limited atmospheric escape from our analysis. Additionally, our analysis of the cumulative XUV flux versus escape velocity shows planets with helium detections above the “cosmic shoreline,” where atmospheres are not thought to be present, suggesting the shoreline needs revision. The unexpected trends revealed in our meta-analysis can contribute to a better understanding of star–planet interaction and exosphere evolution.

White Clover does not Increase Soil N2O Emissions Compared to Ryegrass in Non-Frozen Winter, but Increases CH4 Uptake

As one of the most important forage species in Europe, white clover (Trifolium repens) is a legume that is well recognized for its potential to increase productivity especially under reduced N input. It is hypothesized that legumes have the potential to decrease overwinter soil greenhouse gas (GHG) emissions due to more efficient N recycling as compared to non-legume forbs. We conducted a field experiment recording high-resolution soil nitrous oxide (N2O) and methane (CH4) fluxes during the winter months (December 2019 to March 2020) on a five-year-old grassland in central Germany with white clover, fertilized and unfertilized perennial ryegrass (Lolium perenne), and bare soil. White clover and fertilized ryegrass stimulated soil N2O emissions by 174% and 212% as compared to bare soil, and by 36% and 56% as compared to unfertilized ryegrass, respectively, due to their greater N availability and higher water-filled pore space (WFPS). The estimated cumulative CH4 fluxes under white clover were a net CH4 sink, whereas ryegrass and bare soil were net CH4 sources. Soil N2O fluxes were predominantly regulated by both mineral N and WFPS, while CH4 fluxes were mainly explained by WFPS. N-fertilization during the growing season did not affect off-season N2O and CH4 fluxes in perennial ryegrass plots. The combined non-CO2 global warming potential highlighted the possible mitigation effect of white clover on overwinter GHG emissions. Our findings suggest that GHG emissions from legumes are not offsetting their productive benefits during the non-frozen winter seasons.

Confocal Raman spectroscopy coupled with in vitro permeation testing to study the effects of formalin fixation on the skin barrier function of reconstructed human epidermis

Confocal Raman Spectroscopy is recognised as a potent tool for molecular characterisation of biological specimens. There is a growing demand for In Vitro Permeation Tests (IVPT) in the pharmaceutical and cosmetic areas, increasingly conducted using Reconstructed Human Epidermis (RHE) skin models. In this study, chemical fixation of RHE in 10 % Neutral Buffered Formalin for 24 h has been examined for storing RHE samples at 4 °C for up to 21 days. Confocal Raman Spectroscopy (CRS), combined with Principal Components Analysis, revealed the molecular-level effects of fixation, notably in protein and lipid conformation within the stratum corneum and viable epidermis. IVPT by means of high-performance liquid chromatography, using caffeine as a model compound, showed minimal impact of formalin fixation on the cumulative amount, flux, and permeability coefficient after 12 h. While the biochemical architecture is altered, the function of the model as a barrier to maintain rate-limiting diffusion of active molecules within skin layers remains intact. This study opens avenues for enhanced flexibility and utility in skin model research, promising insights into mitigating the limited shelf life of RHE models by preserving performance in fixed samples for up to 21 days.

Alder expansion stimulates nitrogen oxide (NOx) emissions from southern Eurasian permafrost peatlands

AbstractNitrogen oxides (NOx) play an important role for atmospheric chemistry and radiative forcing. However, NOx emissions from the vast northern circumpolar permafrost regions have not been studied in situ due to limitations of measurement techniques. Our goals were to validate the offline analytical technique, and based on this, to widely quantify in situ NOx emissions from peatlands in the southern Eurasian permafrost region. To this end, we conducted a comparison of online and offline flux measurements in 2018 and 2019 using the synthetic air flushing, steady‐state opaque chamber method. With differences in annual average and cumulative fluxes less than 0.1 μg N m−2 h−1 and 0.01 kg N ha−1 year−1, the online and offline fluxes were in good agreement, demonstrating the feasibility of conducting offline measurements in remote regions without power supply. The flux measurements over 2 years showed obvious NOx emissions of 0.05–0.14 and 0.13–0.30 kg N ha−1 year−1 in the hollow and hummock microtopography of permafrost peatlands, respectively. The rapid expansion of alder (Alnus sibirica) in the peatlands induced by permafrost degradation significantly increased soil mineral N contents and NOx emissions depending on the age of alder (0.64–1.74 and 1.44–2.20 kg N ha−1 year−1 from the alder forests with tree ages of 1–10 years and 11–20 years, respectively). Alder expansion also intensively altered the thermal state of permafrost including the sharp increases of soil temperatures during the non‐growing season from October to April and active layer thickness. This study provides the first in situ evidences of NOx emissions from the northern circumpolar permafrost regions and uncovers the well‐documented expansion of alders can substantially stimulate NOx emissions and thus, significantly affect air quality, radiative forcing, and ecosystem productivity in the pristine regions.

Inspecting PGC 165324 and PGC 977941 Galaxies Using a Combination ofPhotometric and Spectroscopic Methods

Photometric and spectroscopic approaches were utilized to examine the two galaxies, PGC 165324 and PGC 977941. Data releases (DR7 and DR17) from "The Sloan Digital Sky Survey (SDSS)” were employed to acquire the observed data. Then, ellipsoids were fitted via employing the Image Reduction and Analysis Facility (IRAF) with utilising STSDAS Library, the ELLIPS task. Along with the astrometric characteristics, the surfaces’ brightness of the galaxies PGC 165324 and PGC 977941, as well as their magnitudes, cumulative flux, central axis position angles, ellipticities, vertical and horizontal shifts, isophotal shape variables (B4), and also the star-forming rates (SFRs), were analysed and evaluated. It was indicated that the two galaxies, are members of a close pair galaxy system; in addition, they are considered a physical system; the PGC 165324 galaxy was a merging galaxy with a higher SFR. It was likely that the PGC 977941 had separated itself from the galaxy collision and drifted away.

Carbon footprint and carbon balance of three long‐term dryland cropping sequences

AbstractCarbon footprints from plants, soil, and the environment are needed to evaluate C balance of an agroecosystem, which indicates if a system is a C source or sink for mitigating climate change. There is scarce information about C footprint and C balance in dryland agroecosystems. We measured C storage of above‐ and belowground crop biomass, CO2 fluxes, soil C sequestration rates, and C balances of three long‐term (34‐year‐old) dryland cropping sequences from 2016 to 2018 in the US northern Great Plains. Cropping sequences were no‐till continuous spring wheat (NTCW; Triticum aestivum L.), no‐till spring wheat–pea (NTWP; Pisum sativum L.), and conventional till spring wheat–fallow (CTWF). Carbon storage in grain, straw, root, and rhizodeposit were 29%–61% greater for NTCW and NTWP than CTWF. The CO2 flux peaked immediately after tillage, planting, fertilization, and intense precipitation (&gt;10 mm) for 3 months in 2016–2017. Cumulative annual CO2 flux was 8%–37% greater for NTCW than NTWP and CTWF in 2016–2017, but was not different among cropping sequences in 2017–2018. Soil C sequestration rate at 0–10 cm measured from 2012 to 2019 was in the order: NTCW (0.27 Mg C ha−1 year−1) &gt; NTWP &gt; CTWF (−0.23 Mg C ha−1 year−1). Carbon balance remained negative and was not significantly different among cropping sequences but varied by year. Carbon loss increased with increased precipitation, regardless of cropping systems. Although a C source, the legume–nonlegume rotation can reduce C loss due to greater grain C output than other cropping sequences in the semiarid region of the northern Great Plains.