bluuebunny/crossref_metadata_2025 huggingface dataset:
An increase in domestic tap water consumption led to a decline in the groundwater reserves of Delhi
Authors: Ajay Ajay , Sanyal Prasanta
Published: February 2023

Despite the riparian state of river Yamuna and local groundwater reserves, Delhi depends on other rivers to fulfil the rising demand for drinking water.  In the last ten years, the water demand has increased by 39% (2006-2016). In this study, we have tried to understand the domestic water supply system by studying the spatiotemporal variation in the stable isotopic composition of tap water. The stable water isotopes are powerful tracers of hydrological processes in natural and human-managed systems. There are three primary sources with distinct stable water isotopic composition River Yamuna, Upper Ganga canal, Munak canal and local groundwater reserves; the glacial-fed Himalayan rivers and canals fulfil around 90% of the water demand. Numerous government-operated treatment plants in Delhi purify the water from one of the above sources and supply it to consumers. We collected the water sample at every stage of the water supply, from the primary source to the sink, such as samples of canal or river water, raw water before treatment, filtered water after treatment, storage reservoirs, groundwater samples and finally, the household tap waters. Contrary to the river, canal water’s isotopic composition shows no spatial variation. Also, the isotopic composition of raw water is similar to the filtered water, indicating no significant loss due to evaporation or any other hydrological process. However, the isotopic composition of tap water shows considerable variation and deviation from its source value. In most regions, tap water’s isotopic composition is higher than that of source water. In Delhi, among all the other sources, the isotopic composition of surface water is lower than that of groundwater. Thus, only the mixing of groundwater with surface water before supplying it to households can explain the observed large variation in the isotopic composition of tap water. Furthermore, our observation suggests groundwater extraction for domestic purposes has increased from 2019 to 2021. The demand for domestic water per capita is rising with the increase in the population. However, the production of treated water is almost constant and depends upon the raw water availability. The excess extraction of groundwater fulfils the gap between supply and demand. Our study suggests that the surface water (river and canal water), or the number of treatment plants, is insufficient to meet the rising water demand in Delhi, which has led to the overexploitation of limited groundwater reserves in the past few years. Therefore, besides irrigation, the excessive groundwater extraction for domestic purposes results in a drop in the North-west India groundwater table. 
Water and carbon fluxes along a land use gradient in the tropical mountain dry forest of South Ecuador
Authors: Murkute Charuta , Cofrep Franz Pucha , Raffelsbauer Volker , Scholz Sebastian , Limberger Oliver , Carillo-Rojas Galo , Bendix Jörg , Trachte Katja
Published: February 2023

Ecosystems play an important role in controlling the exchange of energy, water and carbon between the land surface and the atmosphere, which contributes to the regulation of the climate through biogeochemical process. Changes in vegetation or biomass impacts the microclimatological conditions of the landscapes with feedbacks to the heat and water budgets. Knowledge about the dynamics and driving factors of the exchange processes contributes to our understanding of the land surface – atmosphere interactions as drivers of the Earth’s surface energy budget.In the Tumbesian mountain dry forest (MDF) in the Laipuna reserve on the western escarpment of the Andes mountains in South Ecuador two eddy-covariance measurement stations have been installed over natural forest and an anthropogenic replacement system to observe atmospheric water and carbon fluxes. The MDF is characterized by a distinct seasonality, which can be divided into a dry (May - December) and wet (November - May) season following the inter-hemispherical shift of the ITCZ. Mean monthly precipitation totals ranges between 50 and 400mm with an annual amount of 650mm, while the temperature varies between 21 – 26°C. The forest ecosystem is dominated by deciduous trees and hold a clear annual cycle in the water budget and carbon sequestration. In the scope of global climate change such water limited landscapes are strongly vulnerable to climatic stress situations which lead to changes in the phenological cycles in the ecosystem associated with feedbacks to the water and carbon cycle. The aim is thus, to investigate the energy, water and carbon dynamics along a land use gradient in order to estimate the impact of deforestation on net-ecosystem exchange and evapotranspiration in the MDF region. The study shows first results of microclimatological conditions, such as radiative fluxes, moisture and soil conditions of both sites as well as water and carbon fluxes.
Greenhouse-gas balance of a drained peatland in western Iceland
Authors: Salimi Asra , Bjarnadóttir Brynhildur , Óskarsson Hlynur , M.Stefánsdóttir Helena , Áskelsdóttir Sunna , D.Sigurðsson Bjarni
Published: February 2023

The uptake and emissions of the greenhouse gasses (GHGs) CO2, CH4, and N2O are strongly linked to terrestrial land use. According to Iceland’s National Inventory Report to the UNFCCC, the single largest component of Iceland‘s overall greenhouse gas (GHG) emissions is the release of GHGs from drained peatland. On the other hand, foreign studies have shown peatland restoration to be a promising measure for reducing emissions of drained areas. Therefore, studies on the GHG-balance of drained and rewetted peatlands are now a very hot topic internationally.Within Iceland, the use of peatland- and other wetland restoration as a GHG mitigation measure is hampered by a lack of more country-specific data on GHG balances of such ecosystems. Therefore, there is an urgent need to increase the research on this topic in Iceland.In this project, the main aim is to gather high-quality data on the GHG dynamics of a drained and restored peatland. The site is located at the farm Lækjarnes in W-Iceland and was drained ca. 50 years ago, but has never been cultivated. That is the land use category of most drained peatland in Iceland, they mostly remain uncultivated and are used for livestock grazing. In this Research, we are using an Eddy covariance system to collect CO2 and CH4 flux data, while N2O fluxes are measured with a static chamber method. The eddy covariance technique has become a “standard method” in ecosystem flux- and process-based research worldwide. We are also measuring auxiliary parameters, such as full energy balance, climatic variables, groundwater levels, soil water and temperature, and more. Our eddy system was installed at the research site in Jan 2023. The site is currently drained and will remain so for the first two years, but then it will be rewetted and the measurements will continue after the rewetting. The specific research goals I have chosen to address in my PhD project are: a) Determine the diurnal, seasonal, and annual CO2, CH4, N2O, water, and energy balances of a drained wetland and b) Determine the initial change in those fluxes following ecosystem restoration (rewetting).  The first preliminary data on CO2, H2O, and CH4 winter fluxes from the drained peatland will be presented at the conference.
Development and validation of flood inundation models for estuaries
Authors: Vasilopoulos Grigorios , Coulthard Tom , Robins Peter , Lyddon Charlotte , Barkwith Andrew , Chien Nguyen , Lewis Matt
Published: February 2023

Estuaries, at the interface between catchment and coast, are vulnerable to flooding from the combination of riverine and marine inputs. High river flows generated from intense precipitation can occur synchronously with high tides and storm surges, amplifying flood hazard. In the United Kingdom 20 million people are estimated to live near estuaries, with estuarine flooding regarded as the costliest impact to these areas and second highest hazard to civil emergency. On-going global warming increases sea-levels and modifies hydroclimate variability, thus affecting river fluxes, tidal maxima and the intensify of storm surges. There is therefore a need for improved methods and tools to understand compound flooding events, their impacts and how they may change into the future. In the present paper we developed a validated flood inundation model for the Conwy estuary in North Wales, one of the flashiest catchments in Britain where flooding makes headline news at least once every year. The Caesar-Lisflood 2D hydrodynamic flow model was combined with a range of publicly available datasets to represent channel bathymetry, land elevation, location and heights of flood defences and the hydraulic roughness across the model domain. The model was forced with recorded time-series (15-minute resolution) of tidal oscillations and river discharge data and validated by comparing simulated water levels against observations from existing water level gauges within the estuarine channel. Flood predictions were validated against observed flood extents extracted from SAR imagery using the Google Earth Engine. Calibrated, ortho-corrected (GRD) C-band interferometric Synthetic Aperture Radar (SAR) images captured by the Sentinel-1 constellation of satellites using a dual-band cross-polarization (VH) was used. SAR images were filtered to remove speckle noise and Otsu’s method of thresholding was adopted to automatically extract inundated areas from each available image. Comparison of model-based simulated flood extents against their SAR-derived equivalents was used as a means to validate the flood inundation model.
Development of a daily gridded wind speed observation product using artificial intelligence in Spain
Authors: Plaza Martin Nuria P. , Khorchani Makki , Azorin-Molina Cesar , Zhou Lihong , Zeng Zhenzhong , Latorre Borja , Vicente Serrano Sergio M. , McVicar Tim R. , Chen Deliang , Guijarro Jose A.
Published: February 2023

Historical near-surface wind speed (NSWS; ~10 m above the ground) measurements from terrestrial weather stations are crucial for assessing NSWS changes and variability and its implications for various socioeconomic and environmental issues, such as wind energy. However, currently there is no all-Spain gridded NSWS observation product with higher spatial coverage than station-based wind series. A new methodological approach based on image reconstruction using artificial intelligence could help to solve this limitation. We use a partial convolutional neural network (PCNN) and station-based NSWS series from the Spanish Meteorological Agency (AEMET) to create a 0.1º daily gridded wind speed observation product over Spain for 1961-2021. The deep neural network is trained with wind data from the ERA5-Land reanalysis (at 9-km grid-spacing, ECMWF), and a mask where grid points with historical wind observations are identified. Thus, the 0.1º resolution wind distribution grid is treated as the pixel values of an image with the masked grid points being pixels to be reconstructed. The training process allows the PCNN model to learn the physical laws, such as momentum conservation, present as internal relationships between pixels in the reanalysis data. The learned laws were then implemented to estimate the wind speed of the masked grid points. During the training process, the PCNN model predictions are iteratively compared to the reanalysis data and improved according to the error (i.e., MAE or RMSE) between prediction and the original reanalysis data. Once trained, the model is applied to NSWS measurements in the target domain to predict wind at locations with no observations. The gridded NSWS product provides a high-resolution wind speed data for whole Spain that respects the available observations and reliably predict wind speed in unsampled places, which is useful to many applications requiring wind information.
Efficiency of carbon dioxide removal by ocean alkalinity enhancement via enhanced weathering of mine tailings
Authors: Weeks Jennifer , Khatiwala Samar , Bullock Liam , Yang Aidong
Published: February 2023

Global mitigation commitments which aim to limit global warming to less than 2ºC require dramatic and rapid reductions in atmospheric carbon dioxide (CO2) over the coming century. Carbon Dioxide Removal (CDR) technologies, whereby CO2 is actively taken out of the atmosphere and “durably” stored terrestrially, geologically or in the ocean could be employed to help reduce or counter-balance CO2 emissions to meet national net zero and net negative mitigation targets. Weathering processes would naturally draw atmospheric CO2 down towards pre-industrial levels over hundreds of thousands of years. One such CDR approach involves accelerating the uptake of CO2 through “enhanced weathering” (EW). CDR through EW of silicate minerals such as olivine or carbonate minerals can be achieved, for example, by spreading pulverized rocks on soils or employing mine tailings in specialized reactors to increase the weathering rate and hence carbon sequestration on decadal timescales. Here, we explore the efficiency of using mining waste to achieve CDR through EW. We exploit the results of a recent study by Bullock et al. (Science of the Total Environment, 2022) which produced one of the first comprehensive assessments of the global and country level suitability of mine tailings, accounting for reaction kinetics, and their potential for CO2 drawdown. While the overall CDR from EW of mine tailings is relatively modest, such an approach may still help individual countries meet their net zero goals and it is useful to investigate the broader implications of the deployment of this approach. EW leads to the production of alkalinity and bicarbonate ions (through CDR). We use Bullock et al.’s estimates of the annual generation of these quantities over the coming century to force an ocean biogeochemical model to investigate the impact of the release of these constituents into the ocean on atmospheric CO2 and ocean chemistry under various emission scenarios. In our simulations, alkalinity and dissolved inorganic carbon (DIC) are injected into the Exclusive Economic Zones of each suitable country or region as identified in Bullock et. al (2022). We examine in particular the competing effects of alkalinity (which increases CO2 solubility) and outgassing of CO2 (both due to the injection of DIC and reduction of atmospheric CO2) on CDR and find that the latter can substantially reduce the efficiency of carbon dioxide removal (by as much as 25% in the lowest emission scenario).
Common high-frequency variations of water storage in remotely sensed soil moisture and daily satellite gravimetry
Authors: Blank Daniel , Eicker Annette , Güntner Andreas
Published: February 2023

Information on water storage changes in the soil can be obtained on a global scale from different types of satellite observations. While active or passive microwave remote sensing is limited to investigating the upper few centimeters of the soil, satellite gravimetry can detect changes in the full column of terrestrial water storage (TWS), but cannot distinguish between storage variations occurring in different soil depths. Jointly analyzing both data types promises interesting insights into the underlying hydrological dynamics and may enable a better process understanding of water storage change in the subsurface.In this study, we investigate the global relationship of (1) several satellite soil moisture (SM) products and (2) non-standard daily TWS data from the GRACE and GRACE-FO satellite gravimetry missions on a sub-monthly time scale. The analysis of these GRACE data on a daily basis could be beneficial for identifying hydro-climatic extreme events such as heavy precipitation or flood events that occur on a sub-monthly basis.We sample all TWS and SM data sets to a common 1 degree spatial resolution and decompose each signal to sub-monthly frequencies by high-pass filtering. We find increasingly large correlations between the TWS and SM for deeper SM integration depths (root zone vs. surface layer). Even for high-pass-filtered (sub-monthly) variations, significant correlations of up to 0.6 can be found in regions with large high-frequency variability. Time spans with particularly large signal variability, that might hint at extreme events, are identified and compared in both in the TWS and the SM time series. Precipitation data were added to the analysis to provide further evidence for the causes/generation of SM and TWS variations.
Measurements of nitrous acid (HONO), hydroxyl (OH), nitric oxide (NO), hydroperoxyl (HO2), and nitrogen dioxide (NO2) in the upper troposphere: is peroxynitrous acid (HOONO) a missing source of HONO?
Authors: Weyland Benjamin , Kluge Flora , Pfeilsticker Klaus , Rohloff Roland , Harder Hartwig , Tadic Ivan , Fischer Horst , Doerich Raphael , Crowley John , Bohn Birger , Taraborrelli Domenico , Rosanka Simon , Obersteiner Florian
Published: February 2023

Discrepancies between expected and observed NO-NO2 ratios in the upper troposphere suggest the presence of an unknown NOX reservoir. We report on airborne remote sensing limb observations from the mini-DOAS instrument on board the HALO (High Altitude Long Range) aircraft during the CAFÉ-Africa (Chemistry of the Atmosphere Field Experiment) campaign in 2018. Nitrous acid (HONO) slant column densities in limb scattered sunlight in the ultraviolet wavelength range retrieved by DOAS (Differential Optical Absorption Spectroscopy) are converted to volume mixing ratios using the O3 / O4 scaling method. Over the tropical Atlantic Ocean, in the cold upper troposphere, HONO is found in excess of what may be expected from known gas phase formation mechanisms or is predicted by the ECHAM/MESSy Atmospheric Chemistry (EMAC) model. At these altitudes (10-15 km), heterogeneous sources of the excess HONO are inefficient and thus unlikely. Therefore, we investigate the possibility of a gas phase HONO source, namely the oxidation of peroxynitrous acid (HOONO) formed in the reactions NO + HO2 and OH + NO2. Since there are no reported atmospheric measurements of HOONO, we use complementary, simultaneous in situ measurements of OH, NO, HO2, NO2, O3 and photolysis frequencies from onboard HALO to make steady state arguments and quantify reaction rate coefficients for both formation pathways and destruction of HOONO by O3, OH, and NO, the last of which may form HONO and NO2.
Personal exposure to UFP from bicycling measurements in Birmingham, UK
Authors: Damayanti Seny , Harrison Roy M. , Pope Francis
Published: February 2023

Cycling activity has benefits for both health and the environment. However, there are also health risks for cyclists due to their direct exposure to air pollutants from on-road vehicle emissions. Higher breathing rates and the proximity to the emission sources while cycling could also increase the health risk for the cyclist. Airborne particle exposure, particularly ultrafine particles (UFP, Dp smaller than 100nm) has been considered to have a detrimental effect on human health. The assessment of exposure to UFP is essential for UFP management, which is also included in a Good Practice Statement by WHO.In this study, we estimated the personal exposure to UFP using mobile measurements (bicycling) between 17 October and 18 November 2022, in Birmingham, UK. The measurements were conducted at three (3) different times (morning, afternoon, and evening) on weekdays and weekends. A miniature particle counter (DiscMini) that measures particle number concentration (PNC), and average diameter with 1s resolution was used. Besides, a similar instrument was also deployed at an urban background site which was passed during the bicycling measurements.A total of 34 trips (~1.5 hours, and ~12km per trip) were completed. Overall, the result revealed that the exposure to PNC varied substantially both spatially and temporally. Relatively higher PNC exposure was found during the morning (MWD) and evening (EWD) trips on weekdays, while the lowest was during morning weekend (MWE) trips. The mean concentration of MWD, EWD, and MWE was 16664#/cm3, 15255 #/cm3, and 4004#/cm3, respectively. A moderate level was observed during the afternoon on weekdays and weekend (AWD, AWE), and evening weekend (EWE) ranging from 8321-9676 #/cm3.During weekend trips, the average geometric mean diameter was observed to be larger (43-52.3 nm), suggesting a greater relative background contribution during the weekend, especially in the morning. All the average PNC from bicycling measurements were 2.3-2.6x higher than that measured at the background site due to more emission sources being present along the route. However, PNC and average diameter measured at the background site revealed similar behaviour to the mobile measurement with high concentrations during morning and evening on  weekdays.Spatial analysis indicated some hotspots that were at intersections and traffic lights. A construction area and shopping park area also exhibited high concentrations, especially during afternoon and evening weekend trips. These results may be of value in support of strategies to mitigate UFP personal exposure, particularly for cyclists who commute daily in this area and on similar routes elsewhere.
Shear-wave velocity structure and Moho depth variation in northern Algeria from joint inversion of teleseismic P-wave receiver functions and Rayleigh wave dispersion from local earthquakes
Authors: Melouk Billel , Yelles-Chaouche Abdelkrim , Semmane Fethi , Galiana-Merino Juan Jose
Published: February 2023

AbstractWe investigated the Moho depth and the velocity structure of the crust and upper mantle in northern Algeria. We used teleseismic P-wave receiver functions jointly inverted with Rayleigh wave dispersion curves obtained from local earthquakes. The events used are collected from the seismic broadband stations of the Algerian broadband seismic network. These stations are located in different geological settings including the Tell Atlas, High Plateaus, and the Saharan Atlas. The H–κ stacking method of receiver functions was applied to first obtain the crustal thickness and the Vp/Vs ratio. The inversion results show the variation in Moho depth in the different geological structures. The shallowest depths of the Moho (~20–30 km) are estimated along the Algerian continental margin and Tell Atlas. In the High Plateaus region, the Moho depths vary from 30–36 km, whereas the deepest Moho depths are found in the Saharan Atlas (36–44 km). The crust is divided in two layers in the whole study area. The upper crust, ~8 –14 km thick, presents an average shear velocity of ~3.0 km/s. The lower crust of about 12–30 km thick has an average shear-wave velocity that ranges between 3.4–3.8 km/s. The upper crust is thinner than the lower crust particularly in the Saharan Atlas. The upper mantle shear-wave velocity varies from 4.1 to 4.5 km/s maximum and is stable, generally, below ~60 km depth. We clearly observed two low-velocity zones particularly in the eastern part of the Tell Atlas and the High Plateaus. The obtained results are in accordance with the previous results found in the region, particularly those using land gravity and seismic data. As the first estimate of the Moho depth from earthquake data in northern Algeria, using the receiver function method, this study sheds new insights on the crustal structure and the Moho depth in this region of the world.
A comparison study of Mg/Ca-, alkenone- and TEX86-derived temperatures for the Brazilian Margin during Marine Isotope Stages 6–5
Authors: Bahr André , Jaeschke Andrea , Hou Alicia , Chiessi Christiano M. , Spadano Albuquerque Ana Luiza , Rethemeyer Janet , Friedrich Oliver
Published: February 2023

The reconstruction of accurate sea-surface temperatures (SST) is of utmost importance due to the central role of the ocean in the global climate system. Yet SST-proxies might be influenced by a number of environmental processes that may potentially bias the accurate reconstruction of the target variable. Here, we investigate the fidelity of SST reconstructions for the Western Tropical South Atlantic (WTSA) for Marine Isotope Stages (MIS) 6–5, utilizing a core collected off eastern Brazil at ~20°S. This interval was selected as previous SST estimates based on Mg/Ca ratios of planktic foraminifera suggested a peculiar pooling of warm surface waters in the WTSA during MIS 6 despite glacial boundary conditions. To ground-truth the Mg/Ca-based SST data we generated SST reconstructions from the same core using both, alkenone and TEX86 paleothermometers. Comparison with alkenone-based temperature estimates corroborate the previous Mg/Ca-based SST reconstructions, supporting the presumed warm-water anomaly during MIS 6. In contrast, while core top samples indicate that TEX86-derived temperatures represent annual mean SST, the TEX86-derived paleo-temperatures are up to 6°C colder than Mg/Ca- and alkenone-based SST reconstructions. We interpret the periods of anomalously cold TEX86-temperatures as a result of a vertical migration of the TEX86 producers (heterotrophic marine Thaumarchaeota) to deeper water depths in response to an increase in food availability during phases of enhanced fluvial suspension input.
Recent data assimilation developments in the Mediterranean Sea Analysis and Forecasting System (MedFS)
Authors: Aydogdu Ali , Pistoia Jenny , Miraglio Pietro , Cipollone Andrea , Grandi Alessandro , Drudi Massimiliano , Clementi Emanuela , Masina Simona , Pinardi Nadia
Published: February 2023

The Mediterranean Sea Analysis and Forecasting System (MedFS) is continuously under development to provide improved ocean state estimates and daily forecasts through the Copernicus Marine Service. Since the beginning of the second phase of Copernicus Marine Service, there have been various upgrades in the data assimilation (DA) component of the MedFS and assimilated observations. MedFS consists of a NEMO-based modelling system coupled with WW3 for improved hydrodynamic representation and it is interfaced to OceanVar, the CMCC 3D variational ocean data assimilation scheme to incorporate observations. Here we present the most important novelties recently included in the operational system which consist in the use of a new observation-based Mean Dynamic Topography (MDT) and a new set of Empirical Orthogonal Functions (EOFs) computed from 35 years of Mediterranean high-resolution reanalysis both covering also the Atlantic side of the domain, as well as the ingestion of Sentinel-6A Sea Level anomaly (SLA) altimeter data. An initial assessment of the assimilation of 5 Hz (~1 km) SLA observations will be presented. Moreover, we will show the impact of the assimilation of glider observations in the Mediterranean Sea with a focus on the western basin. Finally, we will outline our future plans for this phase of the Copernicus Marine Service towards higher-frequency assimilation with an improved background representation and observation operators for satellite products.
Remote sensing techniques to assess the weeds adaptability to salinity stress induced by soil changes
Authors: Nikolić Nebojša , Cucchiaro Sara , Straffelini Eugenio , Tarolli Paolo , Masin Roberta
Published: February 2023

Weeds pose one of the major threats to plant production, as they can reduce yield, interfere with harvest, and host different harmful organisms. Unlike crops, weeds are characterized by great plasticity and adaptability to agroecosystem changes, making them an even more critical threat in a constantly changing environment. The influence of climate change in the form of different stresses to which plants are being more and more exposed is being extensively studied in crops, yet there are few studies concerning weeds. Still, considering the adaptability potential of weeds, they can represent an even more significant threat to agricultural production when abiotic stress, such as salinity, is introduced in the agroecosystem. Currently, remote sensing techniques may be exploited to derive useful, frequent, and low-cost information at different spatial scales. In this work, the Structure from motion (SfM) technique paired with Unmanned Aerial Vehicles (UAV) was used to map the distribution changes of Abutilon theophrasti in July and August 2022 in three different crop fields in the Po river delta, North-Eastern Italy. The multi-temporal orthomosaics obtained by two various SfM surveys had an image resolution of 2 cm, allowing an accurate photo interpretation and the realization of precise maps of species distribution. In the meantime, different soil samples have been taken from the fields above, and their position was measured by a Global Navigation Satellite System (GNSS), GeoMax Zenith 40. The salinity level of soil samples has been determined by measuring the electrical conductivity using XS Instruments COND 80 electrical conductivity meter (Giorgio Bormac s.r.l, Carpi, Italy) at a sensitivity of 1 µS. Salinity values were spatialized in the study areas, realizing salinity maps through the spatial interpolation tools of the Geographic information system (GIS) software. The salinity maps overlapped the maps of single plants of A. theophrasti. In both of the multi-temporal surveys performed, results show that plants of A. theophrasti can be found in areas where the soil salinity is higher than 8 dS/m, where most of the crop plants have perished.  Considering that the weed plants were present at the same place in both surveys, this indicates that A. theophrasti can tolerate the rise of salinity in the fields better than the crop plants and can therefore outcompete them. These results suggest that soil salinization can have a double negative effect on crop production, both causing abiotic stress and increasing competition.
Acknowledgments: This study was carried out within the Agritech National Research Center and received funding from the European Union Next-GenerationEU (PIANO NAZIONALE DI RIPRESA E RESILIENZA (PNRR) – MISSIONE 4 COMPONENTE 2, INVESTIMENTO 1.4 – D.D. 1032 17/06/2022, CN00000022).
Geological fieldwork in the time of COVID-19: Comparing the student learning experience during virtual and outdoor fieldwork
Authors: Laurent Valentin , Guillaume Louise , Genge Matthew
Published: February 2023

Fieldwork is a pedagogical cornerstone of many geoscience degrees. During the academic year 2020-21, the worldwide COVID-19 pandemic made outdoors fieldwork difficult, resulting in an urgent need to develop virtual alternatives. However, there is still more to learn about the impact of teaching fieldwork virtually on the student learning experience. This study aims to compare the student learning experience during virtual and outdoor fieldwork and establish the value of digital techniques to improve the inclusivity of geosciences degrees. Quantitative and qualitative data were collected to assess students’ attitudes to both outdoor and virtual fieldwork in terms of accessibility, inclusivity and their learning experience. Our results show overall positive student responses to virtual fieldwork, with over half stating it adequately replicated the learning experience of outdoor fieldwork. Students also value outdoor fieldwork for the degree of autonomy it provides, and idea-sharing with peers; yet simultaneously the majority believed outdoor fieldwork is inherently exclusionary. This study concludes that virtual fieldwork, taught using interactive three-dimensional virtual outcrops set within virtual worlds, replicates the outdoor fieldwork learning experience as closely as possible. However, students missed some fundamental and important aspects of outdoor fieldwork, such as being outside in an immersive environment, or the social interactions with peers and staff that are specific to on-location fieldwork. This study recommends the use of virtual fieldtrips in addition to residential on-location fieldwork, as for a significant number of students virtual fieldwork may be a better way of accessing this valued pedagogy of the geosciences. Furthermore, virtual fieldwork has the potential to make geosciences more inclusive and attractive to a wider range of students.
Temporal phases of GHG emissions in rewetted fen sites using multiyear ecosystem carbon flux measurements
Authors: Kalhori Aram , Wille Christian , Gottschalk Pia , Sachs Torsten
Published: February 2023

Rewetting drained peatlands is recognized as a leading and effective natural climate solution to curbing greenhouse gas (GHG) emissions. However, CO2 source-to-sink transition is not necessarily detected in years immediately following rewetting and temporal dynamics in carbon budgets can be seen in rewetted systems. Here, we investigate long-term (2008 & 2013 - present) ecosystem flux measurements using the eddy covariance technique, revealing the temporal patterns of annual carbon dioxide (CO2) and methane (CH4) fluxes, in a rewetted peatland site in northeastern Germany. We show that site-level annual emissions presented in this study are only approaching the IPCC default Tier 1 emission factors (EFs) and those suggested for the German national inventory report after 13-16 years of rewetting when the optimum range of water level (close to the soil surface) is reached during the vegetation period. Overall, our results indicate that in addition to annual variation in soil temperature, vegetation development (post-rewetting successional vegetation dynamics) along with water table depth have the greatest effect on the carbon sink function. We further observe a transitional change into a new phase in the ecosystem carbon status throughout the study period that includes a source-to-sink transition of annual CO2 fluxes in 2020. The decreasing trend for CO2 fluxes is estimated at -0.37 t CO2-C ha-1 yr-1 and -44 kg CH4 ha-1 yr-1 for CH4 emissions for the period until 2021.  While we found a strong reduction in CH4 emissions in 2019 (following a severe drought), the negative trend in CH4 emissions in the years before the drought event is still statistically significant (-17 kg CH4 ha-1 yr-1). Accordingly, a considerable reduction of the 100-year annual global warming potential (GWP) and sustained-flux global warming potential (SGWP) was observed during the course of the study and potentially approaching a new steady-state phase within the last few years. In Germany, the published long-term datasets from rewetted peatlands only cover a period of ≤10 years after rewetting, thus, the duration of potential phases and development of future emissions are still unclear. This outlines the need for more long-term datasets to cover the source-to-sink transition in rewetted peatlands that also capture the impacts of likely future climate extremes. Here, we aim to establish a baseline to contribute a better understanding of the transitioning, complexity, and climate sensitivity of rewetted systems by analyzing the dynamics within the site and the inter-annual variability via their respective drivers. The introduction, monitoring, and targeted management of an ensemble of site characteristics (coverage/type of dominant vegetation, average water level along with microclimate and microtopographic conditions) is necessary in understanding the transient nature of such systems and further refine the existing static default EFs.
Realistic freshwater forcing around Greenland in climate models
Authors: Devilliers Marion , Yang Shuting , Olsen Steffen , Drews Annika
Published: February 2023

This study summarizes the findings of several realistic freshwater forcing experiments around Greenland and surrounding regions, which were conducted using climate and ocean models over the historical period. The results of the experiments are discussed in terms of their impact on the Atlantic Meridional Overturning Circulation (AMOC) as well as on temperature and salinity changes in the North Atlantic and in the Arctic. It was determined that the addition of freshwater led to a decrease of the AMOC and a reduction of the temperature and salinity biases in the North Atlantic. These results will be of particular interest to researchers interested in the effects of current and future Greenland melting on local and global ocean. 
Reactive transport in channel flows with bed adsorption and desorption
Authors: Zhan Jie , Jiang Weiquan , Wu Zi
Published: February 2023

Researches on the solute dispersion process with adsorption and desorption at boundaries are common in various fields, such as chemistry, biology and hydraulics. However, the Laplace transform as an available method for the adsorption-desorption boundary conditions, is complicated and difficult to apply. Recently, Jiang et al. (J. Fluid Mech., vol. 947, 2022, A37) proposed a much simpler analytical method based on the classic framework of separation of variables to derive solutions of concentration moments for a tube flow, which is valid for the entire range of the reactive transport process. The key of this approach is to solve the eigenvalue problem for the bulk and surface concentration distributions with the adsorption-desorption boundary conditions. Compared with the Laplace transform method, this new method can effectively avoid the complexity caused by the inverse Laplace Transform. Here we apply this simple approach to solute transport in channel flows with bed adsorption and desorption. We investigate the effect of adsorption-desorption on the dispersion process, and the influence of initial conditions on the non-uniformity of dispersion characteristics over the cross-section before the Taylor dispersion regime.
Interferometric synthetic aperture radar and numerical collapse simulation for residual service life prediction of bridges affected by slow deformation phenomena
Authors: Farneti Elisabetta , Cavalagli Nicola , Venanzi Ilaria , Salvatore Walter , Ubertini Filippo
Published: February 2023

The authors present an innovative approach for structural assessment of bridges undergoing slow deformation phenomena induced by hazard sources such as landslides, ground consolidation, subsidence or foundation scouring. The methodology is multidisciplinary in nature and is based on the combination of displacement measurements derived from Synthetic Aperture Radar Interferometry (InSAR), applied to satellite images, with structural and collapse analyses performed through advanced numerical modelling with Applied Element Method (AEM). InSAR allows to follow the temporal evolution of slow deformations affecting the structure and, exploiting observations from two different viewing geometries of the satellite radar antenna, it is possible reconstructing the two-dimensional movements of a bridge over time, with proper defined error bounds on the estimated displacements. AEM instead is capable of reproducing with a high degree of accuracy the structural behavior from the elastic stage to crack initiation and propagation, steel yielding, up to element separation and collision, therefore is particularly suitable for collapse simulations, allowing to improve the comprehension of the structural behavior and identify the most critical structural elements. The combination of these two powerful tools is aimed at detecting anomalies in the deformation trends, identifying potential critical conditions and evaluating the time to failure of the bridge in the event that the slow movements progress with a trend consistent with the measurements in the monitored period. The application of the methodology to the case study of the Albiano-Magra Bridge, in Italy, which collapsed on April 8th, 2020, is discussed. The integration of InSAR displacement measurement and collapse simulations with AEM has allowed identifying the most probable triggering cause of the collapse and estimating the residual service life of the bridge, whose reliability increases with the extent of the available satellite monitoring period.
Changes in satellite-derived vegetation growth trend in the Tibetan Plateau from 2000 to 202
Authors: Anniwaer Nazhakaiti , Hong Songbai
Published: February 2023

Understanding how vegetation growth responds to climate change is a critical requirement for projecting future ecosystem dynamics, yet the temporal dynamics of vegetation growth on the Tibetan Plateau (TP) remain unclear. Using dataset of satellite-derived Normalized Difference Vegetation Index (NDVI) and solar-induced chlorophyll fluorescence (SIF), we investigated spatio-temporal changes in vegetation growth, the similarities and differences on relative trends of NDVI and SIF growing season mean value on the TP from 2000 to 2021. Results indicate that the east part of TP was greening, but the west part was browning in past 22 years. A piecewise linear regression approach shows that the trend in vegetation growth is not continuous through the 22-year period in two parts. The two satellite products produced different spatial patterns of relative trend, likely indicate changes in light-use efficiency (LUE). Our study highlights the importance of observing vegetation dynamics from multiple datasets and provides insights into investigating LUE dynamics.
Vegetation Simulation from the Colonization of Land Plants to the Present
Authors: Guo Jiaqi , Hu Yongyun , Liu Yonggang
Published: February 2023

Climate affects vegetation growth and distribution, and vegetation affects climate by modifying the exchange of carbon, water, momentum, and energy between atmosphere and land throughout evolution history. Therefore, reproducing the vegetation distribution is of great significance for understanding climate evolution, vegetation evolution, and their interaction. However, a systematic map of global vegetation distribution since the colonization of land plants (about 480 million years ago; Ma) has remained to be determined. Here, Community Earth System Model (CESM) version 1.2.2 and BIOME4 vegetation model are applied to simulate vegetation during the past 480 million years based on modern vegetation parameters. First, the simulations reveal multiple maps of global vegetation from 480 Ma to pre-industrial (PI) period with a 10-million-year interval. 28 biomes show different distribution characteristics with the evolution of climate, and parts of characteristics are supported by palaeobotanical evidence. Second, the potential biomass as a measure of plant growth is analyzed to explore causes of vegetation variations here. The results illustrate plant growth and expansion is significantly affected by terrestrial temperature and CO2 concentration, followed by terrestrial precipitation. Besides, more land area in the middle and low latitudes can be more conducive to plant flourish in geological history. The simulations provide a reference for paleo-vegetation data and some insights into the interaction between climate and vegetation evolution.
Investigating the controls on the development of distally steepened carbonate ramps: A stratigraphic forward modelling of the Upper Miocene distally steepened Menorca ramp, Spain.
Authors: Tella Timothy , Winterleitner Gerd , Morsilli Michele , Mutti Maria
Published: February 2023

Despite the numerous studies dedicated to understanding distally steepened carbonate ramps, the origin of these carbonate systems and controls over their development remain an ongoing discussion. Previous studies have shown the possible impact of climate, tectonics, inherited slope, and differential sedimentation on distally steepened ramp development. However, how these processes create steep slopes in carbonate ramps has yet to be fully understood. To test the role of different processes such as sea-level fluctuation, paleosurface inclination, differential sedimentation, and wave propagation on the geometry of carbonate ramps, we developed a highly constrained stratigraphic forward model referenced to the well-studied Upper Miocene Menorca ramp (Spain). Based on this forward model, several sensitivity analyses were performed and revealed that a complex interaction of changes in accommodation, carbonate production and sediment transport controls steep slope development in carbonate ramps. The results also show that protracted sea level low stand followed by high-frequency sea-level fluctuations with amplitude between 30 m and 40 m favour the initiation of steepened slopes in carbonate ramps. In contrast, models developed with low-frequency and higher amplitude sea-level fluctuations of about 115 m showed no significant slope development. Testing with different inclinations of paleosurfaces shows that flat-to-subhorizontal paleosurfaces result in ramps that mirror the antecedent slope. In contrast, steeper paleosurfaces tend to result in ramps with well-defined slopes. Steeper paleosurfaces also enhance facies differentiation and steep slope development than flat paleosurfaces. Our models, thus, show that the ramp profile becomes more influenced by the depth constraints on the carbonate sediment producers than by the geometry of the underlying topography as the inclination of the paleosurface increases. The models also show that shallow carbonate production tends towards steep slopes due to the low-transport characteristic due to seagrass trapping. This steepness could, however, be altered by the introduction of high-transport sediment grains from deeper carbonate producers, which fill the slopes and more distal sections of the ramp profile.
Nitrous Oxide and Climate
Authors: van Wijngaarden William , de Lange Cornelis , Ferguson James , Happer Will
Published: February 2023

Higher concentrations of atmospheric nitrous oxide are expected to slightly warm Earth's surface because of an increase in radiative forcing.  For current concentrations of greenhouse gases, the radiative forcing per added N2O molecule, is about 230 times larger than the forcing per added carbon dioxide molecule.  This is due to the heavy saturation of the absorption band of the relatively abundant greenhouse gas, CO2, compared to the much smaller saturation of the absorption bands of the trace greenhosue gas N2O.  But the rate of increase of CO2 molecules, about 2.5 ppm/year is about 3000 times larger than the rate of increase of N2O molecules, which has held steady at around 0.85 ppb/year since 1985.  So the contribution of nitrous oxide to the annual increase in forcing is 230/3000 or about 1/13 that of CO2.  If the main greenhouse gases, CO2, CH4 and N2O have contributed about 0.1 K/decade of the warming observed over the past few decades, this would correspond to about 0.00064 K per year or 0.064 K per century of warming from N2O.  This rather small warming does not support placing harsh restrictions on nitrous oxide emissions, which could seriously jeopardize world food supplies.