bluuebunny/crossref_metadata_2025 huggingface dataset:
Using modelling and tools for advice on improved agricultural management to achieve climate neutrality in croplands
Authors: Kuhnert Matthias
Published: February 2023

Cropland soils show large potential to sequester carbon to achieve climate neutrality. Changes in management can affect an increase of carbon sequestration or reducing carbon losses in form of emissions or leaching. However, the impact of management changes on the sequestration and other processes needs to be quantified to provide advice to farmers. Experiments to analyse impacts of management changes are costly and labour intensive. Additionally, these experiments take time and cover only a small range of environmental conditions. Therefore, modelling is widely used to over-come these limitations. Model results allow the estimation of all relevant fluxes for the overall greenhouse gas emission balance or, depending on the model, for some parts. This is a fast and efficient method to quantify soil organic carbon (SOC) changes due to modifications in agricultural management. Even though, models proved their quality of simulating SOC changes, there are some restrictions in the use of models for actual advice based on model results. In the here presented study, three key points will be analysed: First, the additional impacts beside the SOC changes. Carbon sequestration can be offset by emission of other greenhouse gases or management changes affect yield, which needs to be included in the analysis. While these two variables are well covered by usual model approaches, other aspects like food quality are more difficult to include. Second, how does the complexity of the model affect the result. The simple assumption that more complex models are potentially more accurate, but also require more input data is in most cases realistic (this is a generic assumption which is not always true). More input data and more complexity are also associated with potentially increased uncertainty. Third, who is running the model. While research-based advice using more complex models might be potentially more accurate, models used by farmers might be more specific and direct in providing key information. Additionally, the impact of the increased data demand and required data can affect an increased error. These points are analysed on examples and case studies. This includes an analysis beyond the carbon sequestration and how to include these aspects in the analysis. Further, results of a tool developed for stakeholders/farmers is compared with results of a biogeochemical model for selected sites. Finally, an analysis of the limitations of the models due to data demand and data availability. The analysis of wheat yields shows mainly positive impacts on the SOC change, but mainly reduced yield. The comparison of the two models indicates the impracticability of the more complex option, as the data demand is not orientated on the data availability. The decision based on model results requires a careful use of models and a good understanding of the results.
Evaluating the Performance of the WRF model in reproducing the Rainfall Onset and Cessation over Eastern Africa
Authors: Gudoshava Masilin , Bahaga Titike , Barimalala Rondrotiana , Sobolowski Stefan , Atheru Zachary , Demissie Teferi , Artan Guleid
Published: February 2023

Knowledge of the onset, cessation and length of the rainy season is important for decision-making in various climate sensitive sectors over Eastern Africa. In the agricultural sector for example the forecast information on these characteristics can be used to decide on when and what to plant.  We customize the Weather Research and Forecasting (WRF) model over the region and evaluate the skill of producing the onset and cessation over the region. The WRF regional climate model is utilised in sub-seasonal to seasonal forecasting over the region.  We utilize the threshold on accumulated rainfall method for calculating the rainfall onset and cessation as is currently done operationally over the region by the IGAD Climate Prediction and Applications Centre.   The customization experiments focus on the land surface, cumulus and microphysics schemes for the long rains (March-April- May), June to September and the short rains (October-November-December). In this study 3 land surface schemes, 5 cumulus and 6 microphysics schemes are utilized in combination with other physics schemes.  The WRF model is able to simulate the seasonal rainfall over the region. In addition it is shown that some physics combinations represent the onset and cessation  dates  better compared to others. The preliminary results  highlight the usefulness of the WRF model in reproducing the onset and cessation characteristics over the region. 
Thermal and thermocapillary instabilities in a fluid film over a phase boundary
Authors: Sam Darish Jeswin Dhas , Roy Anubhab , Toppaladoddi Srikanth
Published: February 2023

Fluid flows over phase-changing boundaries find relevance in the study of many problems in astrophysical, geophysical, and engineering settings. A detailed understanding of the nonlinear coupling between fluid flow and the moving boundary is often critical to the evolution of the system. Growth of sea ice in the Earth's polar regions and the dynamics of ice sheets and the Earth's interior are a few examples that highlight their ubiquity across scales.Here, we consider the stability of a layer of liquid that is bounded by its solid phase at the bottom and a free surface at the top. The liquid has a temperature of maximum density, Tm, and convective motions in the liquid layer ensue when the temperature of the free surface is greater than Tm. We use a combination of linear and asymptotic analyses to explore the effects of the phase-changing boundary, density anomaly, and the free surface on the thermal and thermocapillary instabilities in this system.
A new methodological approach for the assessment of plastic pollution in estuarine waters: Guadalquivir River (SW Spain)
Authors: Quintana Sepúlveda Rocío , González-Fernández Daniel , Cózar Andrés , Manzano-Medina Sandra , Pérez-López Lucía , Morales-Caselles Carmen
Published: February 2023

Rivers and estuaries are a key transport pathway for plastics from inland to the sea. These systems are subject to fluctuations depending on sources of plastics and local environmental factors, causing variation in the plastic concentration up to several orders of magnitude within limited time ranges. Due to this large variability, in freshwater systems, it is challenging to obtain representative monitoring data. This study presents a new methodological approach to determine the number of plastic particles needed to obtain representative data for plastic pollution characterization in estuarine waters. The method used monthly in situ observations during a period of two years in the Guadalquivir River estuary (SW Spain). The data allowed the characterization of plastic concentrations across all size categories (micro-, meso- and macroplastics). The items were categorized into different size classes (<5 mm, 5-25 mm, 2.5-5 cm, 5-10 cm and >10 cm) and a resampling simulation was applied to generate 95% confidence intervals for plastic concentration variability. Our results suggest that, when using a limited number of samples, there is an underestimation of all size classes, e.g., up to three quarters of the samples could underestimate the average number of particles. Differences up to 3 orders of magnitude can be established between the lower (<5 mm) and the higher (>10 cm) size class in terms of number of particles sampled. This approach will help to optimize time and define sample size for specific particle size classes to improve plastic monitoring in freshwater environments.
Open geospatial standards and reproducible research
Authors: Cannata Massimiliano , Giuliani Gregory , Ingensand Jens , Ertz Olivier , Collombin Maxime
Published: February 2023

In the era of cloud computing, big data and Internet of things, research is very often data-driven: based on the analysis of data, increasingly available in large quantities and collected by experiments, observations or simulations. These data are very often characterized as being dynamic in space and time and as continuously expanding (monitoring) or change (data quality management or survey). Modern Spatial Data Infrastructures (e.g.  swisstopo or INSPIRE), are based on interoperable Web services which expose and serve large quantities of data on the Internet using widely accepted and used open standards defined by the Open Geospatial Consortium (OGC) and the International Organization for Standardization (ISO). These standards mostly comply with FAIR principles but do not offer any capability to retrieve a dataset how it was in a defined instant, to refer to its status in that specific instant and to guarantee its immutability. These three aspects hinder the replicability of research based on such a kind of services. We discuss the issue here and the state of the art  and propose a possible solution to fill this gap, using or extending when needed the existing standards and or adopting best practices in the fields of sensor data, satellite data and vector data.
Ion specific Interactions and Surface Enrichment on Mixed Aerosol Surfaces
Authors: Saak Clara M. , Mika Sofie M. , Backus Ellen H.G.
Published: February 2023

Aerosols have a net cooling effect in our atmosphere, mainly due to their ability to act as cloud condensation nuclei (CCN) and to reflect incoming solar radiation [1]. In aerosols the surface is particularly important as it is the site for many processes which are central to cloud formation, in particular evaporation and condensation. Aerosol surfaces contain a wide variety of organic and inorganic chemical compounds. Understanding the resulting surface structure and composition is a necessary first step in gaining a better understanding of the role aerosols play in the atmosphere.In particular, the surface composition affects the hygroscopicity of the particle and thereby its ability to act as a CCN [2]. While the surface propensity of individual compounds has been studied widely, much less is known about cooperative effects in more complex mixed systems [3]. Here we use sum-frequency-generation (SFG) spectroscopy in conjunction with surface tension data to study whether surface competition or cooperative enhancement can be observed in mixed solutions of halides and acids or alcohols of different chain length.We find that in certain cases the presence of different ions can affect the surface structure in a unique way. However, these effects are not systematic and appear to depend on the specific nature of the interaction between the ions and the respective organic compound. This further highlights that the surface structure of mixed systems cannot be extrapolated from studies of simple solutions. [1] IPCC. Climate Change 2013: The Physical Science Basis. [2] P. Zieger et al., Nat. Commun. 2017, 8, 15883. [3] M.T. Lee et al., Phys. Chem. Chem. Phys. 2019, 21, 8418
Whole Mantle Convection with Two Structures and Timescales of Flow
Authors: Morgan Jason P. , Shi Ya-Nan , Vannucchi Paola
Published: February 2023

Mantle convection has often been debated to be either a mode of ‘top-to-bottom’ whole mantle convection, or flow within separated geochemical ‘reservoirs’ such as a denser layer often proposed to be the origin of lower mantle LLSVPs. Here we propose a straightforward resolution in which plate tectonic downwelling is linked to a ~3000 km-broad N-S circumglobal ‘ring’ of higher-than-average seismic wavespeeds in the lower mantle that has been recognized since the first global models of non-radial seismic structure. In the high-viscosity lower mantle, subduction-linked downwelling occurs at speeds of <~1.3 mm/yr, which is the origin of the long-known ~1.7Ga ‘isochrons’ seen in both hotspot and mid-ocean ridge volcanism.  This ~3000 km-wide great-circle ring of slow downward flow is associated with two antipodal axial spokes of twice-as-fast but still very slow largescale upward flow in the ‘LLSVP’ regions. In addition to this background pattern of large-scale lower mantle circulation, upward counterflow to plate subduction preferentially takes material from a warmer D’’ thermal boundary layer at the core-mantle boundary through ~10-20 mantle plumes that feed a sublithospheric plume-fed asthenosphere. In the lower mantle, the relatively warmer and lower viscosity plumes preferentially rise through and are slowly attracted towards the LLSVP regions by the low-order mode of slow lower mantle flow, with plume-conduits further warming their surrounding LLSVP lower mantle.In this contribution we review the seismological and geochemical observations that support this scenario of two interlocking modes of whole mantle convection with very slow flow in the lower mantle that is linked to and pierced by much faster flow in a D’’-plume-asthenosphere upward flow circuit. We then present 3-D thermomechanical models designed to elucidate under what conditions this mode of flow can arise from a highly variable viscosity mantle with both internal heating and significant heatflow across the core-mantle boundary. Finally we briefly touch on some further implications of this scenario for Earth’s radial mantle structure, supercontinent evolution, the geoid, and the geodynamo.
How calving could affect the future of Thwaites and Pine Island Glaciers
Authors: Barnes Jowan , Gudmundsson G. Hilmar
Published: February 2023

Thwaites and Pine Island Glaciers in the Amundsen Sea Embayment, West Antarctica, are among the fastest evolving on the continent, and hold enough ice between them to raise sea levels by over a metre. In their present states, the two glaciers represent different configurations of floating ice, and therefore may not respond in the same way to changes in ocean forcing. Pine Island Ice Shelf is contained within a bay and provides a large amount of buttressing to its glacier. Thwaites Ice Shelf has two components; a heavily damaged ice tongue and a shelf which is only restrained by a single pinning point. Neither of these provide much buttressing. In our modelling experiments, we prescribe calving rates to the ice shelves of these two glaciers alongside thermal forcing from ISMIP6, to investigate the combined effects of warming oceans and continued calving on the future of the region. We demonstrate the potential impacts of adding the calving process into our model by using a range of constant calving rates. Examining the different responses can tell us how important the process is for each glacier, and how sensitive they are to changes in calving. This in turn can be used to determine whether or not significant effort should be invested in improving calving laws to more accurately predict the future shape of the ice front. 
Warming responses of tropical trees and forest stands explored in an elevation gradient experiment
Authors: Uddling Johan , Dusenge Mirindi E. , Manishimwe Aloysie , Manzi Olivier J. L. , Mujawamariya Myriam , Ntirugulirwa Bonaventure , Tarvainen Lasse , Wittemann Maria , Zibera Etienne , Nsabimana Donat , Wallin Göran
Published: February 2023

The responses of tropical forests to climate change depends on the ability of trees to acclimate to warming, as well as how interspecific variation in these responses affect tree community composition. In a unique tropical elevation gradient experiment in Rwanda, Rwanda TREE, we examine the sensitivity of tropical trees and forest stands to warming and altered water supply. Mixed multi-species plantations (20 tree species, 1800 trees per site) have been established at three sites with large variation in elevation (1300-2400 m) and climate (17-24 °C mean daytime temperature), with additional water and nutrient manipulation treatments being applied at each site. Here we present an overview of results obtained this far regarding: (1) leaf gas exchange physiology; (2) photosynthetic heat tolerance; (3) water-use traits; (4) tree growth and mortality; (5) stand-level tree community composition. We also discuss the potential implications of our findings for the biodiversity and carbon storage of tropical forests in a changing climate.
Seasonal dynamics and temperature sensitivity of soil CO2 efflux in a medium-term warmed subarctic grassland
Authors: Protti Sanchez Fabrizzio , Janssens Ivan , Sigurdsson Bjarni D. , Sigurdsson Páll , Bahn Michael
Published: February 2023

Climate warming is expected to occur stronger and faster in high-latitude terrestrial ecosystems compared to other regions of the world. It has been suggested that high-latitude systems are characterized by large soil C stocks which are highly vulnerable to warming. Warmer conditions can stimulate soil microbes to decompose more soil organic matter and increase the activity of plant roots, therefore, increasing soil CO2 emissions. However, our current understanding of soil warming effects on soil CO2 efflux is largely restricted to short-term warming observations which could over- or under-estimate warming effects. Additionally, the warming effects could vary seasonally, and it is important to consider this variation to better predict how natural ecosystems will respond to prolonged warming.In this study, we aim to assess the seasonal dynamics of soil CO2 efflux in a subarctic grassland under medium-term warming (>10 years) and examine how soil warming modifies the temperature sensitivity of soil CO2 efflux. We take advantage of a geothermally heated grassland in Iceland for 13 years that is part of the ForHot and FutureArctic Research Network. We measured soil CO2 efflux in ambient and warmed plots (from +1°C to +10°C above ambient soil temperature) between mid-2020 and early 2022 and during various field campaigns, we analysed the isotopic composition (δ13C) of soil CO2 efflux for partitioning between biogenic and geogenic soil CO2 and disentangle the soil respiration (a biological process) response to medium-term warming. We found strong seasonality in soil CO2 efflux, with particularly higher fluxes during the growing season. After accounting for the geogenic soil CO2 efflux, we found that long-term warming increases soil respiration during winter, spring, and fall. That means that warmer conditions keep microbes more active during the colder months. However, during summer the response was the opposite and soil respiration was unexpectedly lower in warmed plots. This can be related to decreasing soil C stocks in the topsoil during the first years of warming and lower root biomass and soil microbial biomass, limiting soil CO2 efflux under warming during the growing season. Additionally, we found that the apparent temperature sensitivity of soil CO2 efflux (Q10) decreases with warming in a non-linear way, inducing thresholds at different soil warming levels. From these results, we conclude that medium-term warming effects on soil CO2 efflux vary seasonally and warming decreases the temperature sensitivity of soil respiration.
Key Role of Equilibrium HONO Concentration over Soil in Quantifying Soil-Atmosphere HONO Fluxes
Authors: Bao Fengxia , Cheng Yafang , Kuhn Uwe , Li Guo , Wang Wenjie , Kratz Alexandra , Weber Jens , Weber Bettina , Pöschl Ulrich , Su Hang
Published: February 2023

Nitrous acid (HONO) is an important component of the nitrogen cycle in the atmosphere. Photolysis of HONO generates hydroxyl (OH) radicals and significantly influences the atmospheric oxidative capacity. Early laboratory work discovered that soil nitrite, produced via biological nitrification or denitrification, can be an important HONO source. However, the laboratory-determined chamber HONO fluxes can largely deviate from those in the real world for the same soil sample. Therefore, quantification of soil fluxes of HONO in the atmosphere remains challenging. [HONO]*, the equilibrium gas-phase concentration over the aqueous solution of nitrous acid in the soil, has been suggested as a key parameter for quantifying soil fluxes of HONO; but it has not yet been well-validated and quantified. In this project, we present a method to retrieve [HONO]* by conducting controlled dynamic chamber experiments with soil samples and validate the existence of [HONO]* over the soil. We show that [HONO]* is a soil characteristic, independent of HONO concentrations in the chamber. Therefore, it is reliable to use [HONO]* to quantify soil fluxes of HONO. [HONO]* performs as an indicator of the potential of soil to be a source or a sink for atmospheric HONO and helps to better quantify the role of HONO fluxes of soil in the HONO budget and its implications on the oxidizing capacity in the atmosphere. 
Correlating flow field with river bank erosion opposite to an accreting bank: a large-eddy simulation approach
Authors: Chakraborty Pratik , Valero Daniel , Vargas-Luna Andrés , Bregoli Francesco , Crosato Alessandra
Published: February 2023

Bank erosion in riverine systems is one of the most complex, yet rampant, morphodynamic processes with significant implications for riparian activities and thereby the population. Therefore, it is an important aspect of the geomorphological evolution of a river reach that must be taken into consideration by river engineers while planning training, restoration or other engineering works of interest. Erosion of river banks are in essence a result of a combination of bank material entrainment by the river flow and mass failure.In particular, it has been found that bank accretion on one river side could play an important role in triggering erosion of the opposite bank. Such bank accretion could be a result of a natural bar formation due to morphodynamic instability or even forced by an intervention, such as a groyne. To understand this process, we conducted a computational fluid dynamics (CFD) numerical study.  We set up a high-resolution 3D Large Eddy numerical model replicating data-rich experiments which have been previously conducted in a large flume with a mobile bed, where bank erosion has been observed opposite to a bar formation.The CFD hydrodynamic model takes as input the boundary conditions and the high-resolution bed topography data which had been collected during the experiment at given time intervals. The hydrodynamic simulation runs until steady-state, thus provides the flow field at that given time of the experiment, i.e., for a particular bed topography configuration. Thereafter, the next time-instances, with an updated bed topography, are simulated similarly. This provids a set of flow-field data for each time instance. The evolution of the flow field can then be related to the evolution of the opposite bank erosion. Various flow field variables and parameters such as near-bank velocities and Q-criterion, were analysed so as to determine the process driving factors. Furthermore, the large eddy simulations allowed for the identification of coherent turbulent structures and their role in driving bank erosion. Results are here presented and discussed.
Changes in cloudiness cause a changing seasonality in the Baltic Sea region
Authors: Post Piia , Aun Margit
Published: February 2023

In the Baltic Sea region, a significant decrease and subsequent increase in solar radiation have been detected during the past half-century. But the rise in shortwave irradiance is not seen for all seasons; significant changes appear in the seasonality of the cumulative sum of daily shortwave irradiance and the sea surface temperature of the Baltic Sea. Kahru et al. (2016) show that the accumulated surface incoming shortwave (SIS) energy has decreased in winter and increases during the spring and summer. The cumulative thresholds of surface incoming shortwave irradiance up to 1000 W/m2 are reached later in the season, but higher thresholds are reached earlier. The shift from later towards earlier cumulative thresholds occurs in spring, around March 15.Changes in shortwave irradiance are associated with atmospheric transparency and cloudiness parameters like cloud fraction and albedo. The more substantial factor here is cloudiness, and therefore, we concentrate on reasons for changes in cloud properties. One of the most important reasons here is the synoptic-scale atmospheric circulation. The satellite-based cloud climate data record CLARA-A2 has been used to analyse regional time series and trends in the Baltic Sea region, from 1982-2019. The investigated cloud parameters were total fractional cloud cover (CFC) and SIS.In March the interannual variability in CFC is high. The Increasing trend in incoming shortwave radiation could be explained by the decrease in CFC. The decrease in CFC is due to a smaller number of overcast days, that vary in the same rhythm with “cloudy” circulation patterns. This shows, that the shift in seasons that is connected to the earlier accumulated sums of SIS is at least partly explained by the changes in synoptic-scale atmospheric circulation. 
Ice- Ocean - Atmosphere interactions in the Arctic
Authors: Fotheringham Morag , Gourmelen Noel , Slater Donald
Published: February 2023

Arctic glaciers and ice caps are currently major contributors to global sea level rise. The monitoring of smaller land-ice masses is challenging due to the high temporal and spatial resolution required to constrain their response to climate forcing. This dynamic response of land-ice to climate forcing constitutes the main uncertainty in global sea level projections for the next century. The relative significance of these forcings is currently unknown with most recent categorisations focusing on separating loss caused by internal dynamics versus surface mass balance changes, with only initial investigations into processes instigating these changes. This leaves the specific roles of processes in the atmosphere, ocean and sea ice unconstrained. This knowledge is key to improving our projections of how these smaller land-ice masses will respond to future climate forcing and by extension their contribution to future sea level rise.This study uses CryoSAT-2 swath interferometric radar altimetry to provide high spatial and temporal observations to produce elevation timeseries for the land-ice masses in Svalbard Archipelago. It also utilises the regional atmospheric model (MAR) to gain timeseries of surface mass balance. These are combined with climate datasets, and by separating land-ice mass into land versus marine terminating, are used to quantify the effects of different processes. Additionally, in order to observe the relative impact of atmospheric versus oceanic forcing, an ocean thermal forcing model, previously used to study Greenland’s outlet glaciers, has been initialised.The aim of this case study is to develop a framework that will quantify the connections and processes linking loss of land-ice to processes in the ice and, atmosphere and sea ice across the Arctic region.
Routes of Interaction – Research on pre-modern route-setting, pedogenic and geomorphic effects of trampling, and feedback mechanisms between pathways and gully erosion in the Northern Ethiopian Highlands (Tigray)
Authors: Busch Robert , Hardt Jacob , Nir Nadav , Pfeiffer Kristina
Published: February 2023

In order to investigate the interaction between different human societies and their effect on the natural environment, we focus on three main questions. 1: Where were historical settlements located? 2: Where have the routes connected these settlements passed? 3: How have both these settlements and routes interacted with local pedological and geomorphological processes? The northern Ethiopian Highlands (Tigray) have a documented settlement history spanning at least the last three millennia. Some sites have a centuries- or even millennia-long settlement continuity and the reconstruction of their entanglement can help to learn about the interaction between past societies. Pathways, be it over long- or short distances, provide the potential to investigate past and present decision-making processes in route planning. Furthermore, pathways are an impressive example of human-environment interactions. These pedogeomorphological expressions of human trampling on the same piece of land over a certain period of time have different soil characteristics (soil compaction, pedogenic iron contents) than adjacent land areas and can influence the surface hydrology. Under certain conditions in hilly terrain, pathways can either stabilize or destabilize the landscape, depending on their orientation with regard to the local hydrological network, and their degree of incision into the surface (holloways). As such, we analyzed geomorphic and pedogenic properties of pathways as well as feedback mechanisms between pathways and gully erosion, and how these may influence route planning. The reconstruction of historical routes in northern Ethiopia using a combined approach of geolocating historical travel reports and historical maps dating back to the 15th century as input data for least-cost-path analyses, have the potential to reveal points of interest for further archaeological research.
Track and trace: how aeolian dust can help to understand East African climate
Authors: Meyer Inka , Verschuren Dirk , De Batist Marc
Published: February 2023

Samples of present-day aeolian dust collected with the help of various kinds of dust sampling devices are currently a widely used resource to measure distinct characteristics of aeolian transported material, such as variations in the amount of dust flux over space and/or time, chemical and mineralogical composition and isotopic signatures of the material to ultimately infer the origin of the aeolian transported sediment, to understand transport pathways and to identify the sensitivity of aeolian dust to changes in local or global climate variability. However, so far the majority of samples captured by dust traps originate from classical desert environments, such as the Saharan desert or the Australian or Asian deserts. Due to smaller sample amounts, longer depositional periods, difficulties in installing the traps, and labor-intensive trap maintenance, continuous dust-trap records from semi-arid regions are rare.In this study we present a record of aeolian dust deposits from the semi-arid region at Lake Chala, in SE Kenya/ NE Tanzania, comprising a nearly continuous sampling period of 5 years from three different locations. The first dust traps were installed in 2016 during the ICDP DeepCHALLA drilling and deliver a monthly record of dust characteristics in the area. A combination of microscopic investigations, detailed grain-size measurements, as well as mineralogical analysis allows us to infer changes in the amount and characteristics of the monthly deposited aeolian sediments and provide a first insight into seasonal changes and fluctuations of atmospheric forcing factors responsible for dust transport and the deposition in our study area.
Modelling the Uptake and Exchange of Microplastics in Marine Ecosystems using a Novel, Integrated System of High-Resolution Numerical Models
Authors: Coyle Róisín , McKinley Jennifer , Hardiman Gary , Service Matthew , Witte Ursula
Published: February 2023

Microplastics (mPs), defined as plastic particles that are less in 5mm in size, are ubiquitous within the marine environment. They are difficult to remove from natural water streams and persist for long periods of time, breaking down into continually smaller particles. Since the diversity of organisms that can ingest plastic particles increases as the particle size decreases, microplastics have been identified as an emerging contaminant of concern in the marine environment and the determination of the potential ecological harm caused by mPs is a key objective of the EU Marine Strategy Framework Directive (MSFD 2008/56/EC). However, the completion of a comprehensive risk assessment of this marine pollutant is prevented by the current lack of consensus on the processes influencing mP transport, uptake and exchange in the marine environment. For example, the processes driving the transport of mPs with buoyant polymers to the deepest part of the ocean are surrounded in uncertainty. The potential for mPs to accumulate within organisms and consequently the significance of trophic transfer as an uptake route for mPs is also unclear, particularly at lower trophic levels where contrasting arguments have formed on the risk of trophic transfer of mPs via zooplankton.In this study, an integrated system of numerical models has been proposed to improve our understanding of mP processes in the marine environment by simulating the transport and ecosystem uptake and exchange of mPs at lower trophic levels in the northwest European continental shelf region. The continued refinement of the mathematical models will be presented, including the results of tests undertaken to evaluate the efficacy of empirical models for the calculation of the vertical settling velocity of irregularly-shaped particles from the perspective of mP transport modelling. Based on the current availability of data on mP distribution and uptake by lower trophic level organisms in the study area, the feasibility of model implementation will be examined as well as the significance of this research in providing information required by policy makers to complete risk assessment and implement suitable management strategies for marine mP pollution.
A new landslide database for Iceland: what it tells us.
Authors: Drouin Vincent , Stefani Martina
Published: February 2023

Landslides pose a considerable risk over communities and infrastructure in Iceland. There have been large landslides in the recent years and a least one related to permafrost. Taking into account the changing climate, knowing past and active moving slopes increases preparedness for civil protection purposes. In order to have a better overview of the actual hazard, we mapped and classified all landforms reminiscent of landslides into a database. The mapping was done using aerial orthophotos, digital elevation models (DEM), and satellite interferometry (InSAR) velocity map. To begin with, this allows to extract statistics about the spatial distribution and size of various type of landslides. The largest landslide features mapped covers over 10 km2, the smallest below 100 m2. The most common type of large landform can be classified as complex: a mix of slide and slow flow. As expected, most landslides are located where there is steep topography: the West Fjords, the Trollaskagi peninsula, and the East Fjords. However, the distribution of landslide landforms is extremely varied within these areas. Some valleys show numerous landslides while other none. To help figuring out this heterogeneity, this database is put into relation with other type of geographical information: digital elevation models, lithology, bedrock geology, volcanic systems, faults, hydrology, permafrost, ground deformation velocities, constructions and infrastructures.
Estimation of exhaust emissions of inland shipping - a case study on German waterways
Authors: Weber Daniel , Stachel Hauke , Schröder Michael , Noss Christian
Published: February 2023

Traffic is a significant contributor to anthropogenic air pollution. Although inland shipping constitutes only a small part of the total traffic and transports cargo very energy-efficient, inland vessels emit not negligible amounts of pollutants like nitrogen oxides and particulate matter. In order to quantify the contribution of inland transportation to the air pollution as well as to develop necessary strategies to mitigate current emissions, exact knowledge about vessel-born emission rates along waterways are required.A mechanistic model has been developed to simulate fuel demand and emission rates of inland vessels with high temporal and spatial resolution. It links ship positions reported in the signals of the Automatic Identification System (AIS) with representative emission factors of inland vessel engines. The resistance, propulsion and brake power are calculated for each point of a vessel’s trajectory. Emission rates for quasi steady-state estimations of the brake power will be obtained via power-related emission factors. The integral of a large number of these point values ​​provides a quantification of inland shipping emissions along a waterway, e.g., in section-related emission rates.This new model was applied on relevant German inland waterways. We present current exhaust emission rates and an example for a simulation to evaluate the mitigation potential of a modernized fleet.
DOM accumulation in oligotrophic surface waters: new insights from the Mediterranean Sea
Authors: Bachi Giancarlo , Furia Marta , Balestra Cecilia , Casotti Raffaella , Civitarese Giuseppe , Cossarini Gianpiero , Guerrazzi Mirco , Repeta Daniel , Ribera d'Alcalà Maurizio , Santinelli Chiara
Published: February 2023

Dissolved Organic Matter (DOM), the largest pools of reduced carbon on Earth, represents the major source of energy for micro-heterotrophs, starting the microbial loop. In the open ocean, most of the autochthonous DOM is labile and is therefore respired within days, but a small fraction, called recalcitrant, persists for years to millennia. There are large oligotrophic areas in the oceans, such as the North Atlantic subtropical gyre and the Mediterranean Sea, where the decoupling between production and consumption of DOM leads to its accumulation with implications for the microbial loop.The main goal of this study is to investigate the putative functioning of the microbial loop all across the Mediterranean Sea following the main path of the Atlantic water entering through the Gibraltar Strait. Dissolved Organic Carbon (DOC) concentration and fluorescence of chromophoric DOM were measured together with heterotrophic prokaryotes, nanoflagellates and virus abundance by flow cytometry. Samples were collected during the MSM72 oceanographic cruise carried out in March-April 2018. Results show that in the western Mediterranean Sea the heterotrophic prokaryotes are relatively abundant and DOM is efficiently removed, suggesting an active transfer of carbon to the higher trophic levels. In contrast, in the eastern Mediterranean Sea DOM accumulates, prokaryote abundance is low and low nucleic acid prokaryotes dominates, suggesting a malfunctioning of the microbial loop leading to a less efficient carbon transfer to the food web. Following the core of the Atlantic Water flowing eastward, as the nutricline deepens, an ecological succession in the phytoplankton communities (from picoeukaryotes to cyanobacteria) is observed, together with a depletion of the fluorescent components in the DOM pool, reflecting changes in the DOM quality.Different hypotheses can be formulated to explain these observations: the microbial communities could be limited by nutrient availability, by an enhanced top-down pressure by grazers or viruses or by the quality of DOM that could be recalcitrant due to abiotic processes such as photobleaching or to the progressive use of its labile fraction by micro-heterotrophs.With the upcoming increase in water column stratification, a change in the quality of DOM due to the combined effect of abiotic (e.g., photobleaching) and biotic (e.g., change in the phytoplankton community) is expected with consequences for the functioning of the microbial loop. The questions about the malfunctioning of the microbial loop and its implications in a global change scenario have puzzled the scientists for years and the Mediterranean Sea is a well-suited natural laboratory to answer them.
Clay mineral alignment during early stages of burial
Authors: Lang Dustin , Kuehn Rebecca , Kilian Rüdiger
Published: February 2023

The formation of crystallographic preferred orientations (CPO/texture) in sediments is often attributed to rigid grain rotation of minerals and aggregates, plastic-brittle deformation and dissolution-precipitation processes. Due to their platy habit, clay minerals have a large shape anisotropy and are expected to develop a CPO most readily under favorable conditions. Here, we present an experimental approach in order to quantitatively explore the influence of particle settling and subsequent compaction in an undisturbed, ideal environment.For the experiments, a powder of idiomorphic kaolinite grains (texture-forming components) was mixed with a fine-ground, illite aggregates (texture-inhibiting components) in mass proportions of 0, 30, 50, 70 and 100 %. The illite aggregates have compact shapes and are built up of submicron-sized crystallites. The modal particle size of both components is about 5 µm. Particles were mixed with artificial seawater and the resulting sludge was left to settle in 80 cm high acrylic tubes. For each composition three samples were produced: Sedimentation-only and two drained compaction experiments. The latter were carried out in a in a mechanical press, progressively applying a uniaxial load up to 0.4 MPa and 4 - 8 MPa, respectively. Compaction resulted in a volume decrease of 30 and 60 vol-%. The CPO of clay minerals was measured using high energy X-ray diffraction at beamline P07b at Deutsches Elektronen-Synchrotron (DESY) in Hamburg and pole figure data was directly extracted using single peak evaluation.The results show that sedimentation alone, can yield a strong texture of the clay minerals. In the compaction experiments, texture strength is logarithmically related to the applied load, i.e. increase of texture strength is decreases at higher loads. Texture strength is linearly related to shortening and porosity reduction. In all cases, kaolinite texture strength is inversely correlated with illite aggregate content.The results indicate that only a fraction of clay minerals is deposited flat on the sediment surface. Further, alignment during settling is hampered in the presence of particles with compact shapes. It is interpreted that rigid body rotation is limited to the very initial stages of settling and compaction. Additional texture strengthening is hampered by the lack of particles prone to rotate. Sediment surface processes as well as rigid body rotation during initial loading in the first few centimeters of burial are thus the most important processes in the formation of a CPO in clay rich sediments. Subsidence history beyond principal porosity elimination does not have a strong impact on the CPO. Therefore, the texture strength of a fine-grained sedimentary rock can be indicative of settling and early compaction conditions. In return, texture-related properties of artificial clays can be regulated by controlling those conditions.
Transport and emissions of gaseous air pollutants in a high-traffic urban street canyon
Authors: Sungur Leyla , Babel Wolfgang , Arzberger Sophie , Ramer Sophia , Schneider Johann , Bachmann Frederik R. , Bamberger Ines , Nölscher Anke , Thomas Christoph
Published: February 2023

Urban air quality directly determines urban quality of life. To improve it, we need to know about local emissions, chemical transformations, and transport processes of the energy-containing vortices in the air. The combination of high-resolution ultrasonic anemometers and state-of-the-art vortex-resolving Large Eddy Simulation (LES) technique is a powerful key tool enabling this understanding. Here, we investigated the dynamics and transport of air with particular focus on nitrogen dioxide (NO2) in a highest-traffic street canyon with eight driving lanes in the urban setting of the city of Munich, Germany. Using spatially distributed observations and results from flow-resolving simulations, temporally and spatially resolved patterns and trends of airflow and pollutant concentrations are presented. The airflow conditions in the wide (approx. 80m) urban street canyon are largely decoupled from the synoptic flow over the city. The street is mostly characterized by a channeled, northerly current and weak wind speeds and turbulence kinetic energy (TKE) during the day, independent of prevailing synoptic forcing conditions. At night, the channeled current shifts to southern flow and reverses back to northerly winds in the early morning transition. One exception to this rule are infrequent synoptic easterly flows perpendicular to the street canyon orientation, which lead to a deflection of the flow by the building fronts and a flow reversal to westerly flows at the street level. In this case, TKE is strongly enhanced, and pollutant concentrations are low due to enhanced mixing and inflow of less polluted above-city air. Emission coefficients from the Handbook for Emission Factors for Road Transport (HBEFA) have been used in combination with traffic demand data from loop detectors to compute the respective NO2 emissions. These emissions show daily peaks in the morning and afternoon hours, and a significant differentiation between weekday, Saturday, and Sundays with less traffic. The individual lanes also differentiate in amount of emission. Linking the results from the point turbulence and NO2 measurements with the LES approach helps to understand the turbulent air transport and NO2 in parts of the street canyon where no observations exist. The first results from an LES run in a twofold nested domain with a spatial resolution of Δx,y,z = 1m for the street canyon and buildings show promising similarities in airflow patterns and dynamics compared to the observations and are currently undergoing further validation. This study is financed by the Bavarian Ministry of the Environment and Consumer Protection.
The current state and prospects for the development of geotourism in the Jeti-Oguz Valley in the Issyk-Kul Region, Kyrgyzstan
Authors: Bozzhigit kyzy Tolgonai , Kostrzewski Andrzej , Majewski Mikołaj
Published: February 2023

In recent decades, the tourism industry has become one of the key sectors in the global economy, which is related not only to the number of people employed in tourism services but also to significant revenues from tourism to state budgets. Along with the development of tourism and the increase in the number of tourists, the new so-called phenomenon of "overtourism" has appeared. It causes various negative effects on nature as well as on society. Therefore, in recent years sustainable development of regions in all areas of the economy has been emphasized, especially in the tourism industry. This process is mainly implemented in highly developed countries; however, the problem is likewise significant in developing countries, including Central Asia. Geotourism fits perfectly into this trend, as residents and tourists benefit from it, and public awareness of the environment is a positive side effect. In addition, geotourism can serve as a powerful tool in educating society about the protection of abiotic and biotic elements of the natural environment.The main aim of the study is to analyze the current state and prospects for the development of geotourism in the Jeti-Oguz Valley in the southern part of the Issyk-Kul Region, Kyrgyzstan. This region is one of the most attractive destinations for tourists throughout Central Asia. The Jeti-Oguz Valley was selected as an area for detailed research based on geoinformation analysis of individual elements of the natural environment.The analysis of the current state and prospects for the development of geotourism is primarily based on a detailed inventory of georesources and tourist infrastructure of the Jeti-Oguz Valley. The inventory was supplemented by surveys among the local community. Based on the collected research material, a SWOT (Strengths, Weaknesses, Opportunities, and Threats) analysis was carried out regarding the further development of geotourism in the Issyk-Kul Region.