- Geosciences, Vol. 9, Pages 53: Multi-Source Based Spatio-Temporal Distribution of Snow in a Semi-Arid Headwater Catchment of Northern Mongolia
Knowledge of the duration and distribution of seasonal snow cover is important for understanding the hydrologic regime in mountainous regions within semi-arid climates. In the headwater of the semi-arid Sugnugur catchment (in the Khentii Mountains, northern Mongolia), a spatial analysis of seasonal snow cover duration (SCD) was performed on a 30 m spatial resolution by integrating the spatial resolution of Landsat-7, Landsat-8, and Sentinel-2A images with the daily temporal resolution of Moderate Resolution Imaging Spectroradiometer (MODIS) snow products (2000–2017). Validation was achieved using in situ time series measurements from winter field campaigns and distributed surface temperature loggers. We found a mean increase of SCD with altitude at approximately +6 days/100 m. However, we found no altitude-dependent changes in snow depth during field campaigns. The southern exposed valley slopes are either snow free or covered by intermittent snow throughout the winter months due to high sublimation rates and prevailing wind. The estimated mean SCD ranges from 124 days in the lower parts of the catchment to 226 days on the mountain peaks, with a mean underestimation of 12–13 days. Snow onset and melt dates exhibited large inter-annual variability, but no significant trend in the seasonal SCD was evident. This method can be applied to high-resolution snow mapping in similar mountainous regions.
- Geosciences, Vol. 9, Pages 52: First Macro-Colonizers and Survivors Around Tagoro Submarine Volcano, Canary Islands, Spain
Tagoro, the youngest submarine volcano of the Canary Islands, erupted in 2011 South of El Hierro Island. Pre-existing sea floor and inhabiting biological communities were buried by the newly erupted material, promoting the appearance of new habitats. The present study pursues to describe the first metazoans colonizing different new habitats formed during the eruption and to create precedent on this field. Through dredge and remote operated vehicle samplings, five main habitat types have been detected based on the substrate type and burial status after the eruption. Inside the Tagoro volcanic complex (TVC), two new habitats are located in and around the summit and main craters—hydrothermal vents with bacterial mats and sulfurous-like fields mainly colonized by small hydrozoan colonies. Two other habitats are located downslope the TVC; new hard substrate and new mixed substrate, holding the highest biodiversity of the TVC, especially at the mixed bottoms with annelids (Chloeia cf. venusta), arthropods (Monodaeus couchii and Alpheus sp.), cnidarians (Sertularella cf. tenella), and molluscs (Neopycnodonte cochlear) as the first colonizers. An impact evaluation was done comparing the communities of those habitats with the complex and well-established community described at the stable hard substrate outside the TVC, which is constituted of highly abundant hydrozoans (Aglaophenia sp.), antipatharians (Stichopates setacea and Antipathes furcata), and colonizing epibionts (e.g., Neopycnodonte cochlear). Three years after the eruption, species numbers at Tagoro were still low compared to those occurring at similar depths outside the TVC. The first dominant species at the TVC included a large proportion of common suspension feeders of the circalittoral and bathyal hard bottoms of the area, which could have exploited the uncolonized hard bottoms and the post eruptive fertilization of water masses.
- Geosciences, Vol. 9, Pages 51: Climate Change-Induced Migration in Coastal Bangladesh? A Critical Assessment of Migration Drivers in Rural Households under Economic and Environmental Stress
Discussions of climate migration have recognized the need for probabilistic, systematic, and empirical analyses. We examine the importance of environmental stressors in migration using a multi-leveled analysis of a household survey of the climate-stressed rural communities of coastal Bangladesh. We find that a relatively small share (6.5%) of rural coastal people have migrated, overwhelmingly domestically and on a temporary basis. The main motives are better employment opportunities in urban areas, marriage/family reunification, and education. About a third are displaced by flooding that created loss of arable land. Being male, younger, and working outside of agriculture facilitate migration, and also those with greater human and horizontal social capital are more likely to migrate. Exposure to severe river erosion, residing closer to major waterways and in saltwater shrimp farming zones spur migration. Climate migration is in its first instance economic-induced with environmental stress contributing as a secondary factor.
- Geosciences, Vol. 9, Pages 50: Biogeochemical Characterization of Metal Behavior from Novel Mussel Shell Bioreactor Sludge Residues
Acid mine drainage (AMD) remediation commonly produces byproducts which must be stored or utilized to reduce the risk of further contamination. A mussel shell bioreactor has been implemented at a coal mine in New Zealand, which is an effective remediation option, although an accumulated sludge layer decreased efficiency which was then removed and requires storage. To understand associated risks related to storage or use of the AMD sludge material, a laboratory mesocosm study investigated the physio-chemical and biological influence in two conditions: anoxic storage (burial deep within a waste rock dump) or exposure to oxic environments (use of sludge on the surface of the mine). Solid phase characterization by Scanning Electron Microscopy (SEM) and selective extraction was completed to compare two environmental conditions (oxic and anoxic) under biologically active and abiotic systems (achieved by gamma irradiation). Changes in microbial community structure were monitored using 16s rDNA amplification and next-generation sequencing. The results indicate that microbes in an oxic environment increase the formation of oxyhydroxides and acidic conditions increase metal mobility. In an oxic and circumneutral environment, the AMD sludge may be repurposed to act as an oxygen barrier for mine tailings or soil amendment. Anoxic conditions would likely promote the biomineralization of sulfide minerals in the AMD sludge by sulfate reducing bacteria (SRB), which were abundant in the system. The anoxic conditions reduced the risk of trace metals (Zn) associated with oxides, but increased Fe associated with organic material. In summary, fewer risks are associated with anoxic burial but repurposing in an oxic condition may be appropriate under favorable conditions.
- Geosciences, Vol. 9, Pages 49: Review of Approval of Flexible Rockfall Protection Systems According to ETAG 027
In 2009, the European Guideline for Flexible Rockfall Protection Kits European Technical Approval Guideline 027 (ETAG 027) became valid. The aim of the guideline was to approve and certify steel barriers available on the market according to a common standard. In 2018, ETAG 027 was replaced by a so-called European Assessment Document (EAD). This contribution summarizes results and experiences that were obtained through the type testing, approval and assessment procedures of 66 protection systems evaluated between 2009 and 2018. Apart from the common main task of the barriers to stop falling blocks successfully, the different test conditions and constructions of barriers result in different performance characteristics. Some of these characteristics follow certain trends, whereas others show a wide range without any trend. In such a case, this contribution helps to classify a single system compared to the others.
- Global meta-analysis of the relationship between soil organic matter and crop yields
Global meta-analysis of the relationship between soil organic matter and crop yields Emily E. Oldfield, Mark A. Bradford, and Stephen A. Wood SOIL, 5, 15-32, https://doi.org/10.5194/soil-5-15-2019, 2019 In this paper, we quantify the global-level relationship between soil organic matter and crop yield. We find that greater concentrations of soil organic matter are associated with greater yields and that increases in yields saturate around 2 % SOC. Using the relationship that we generate, we then provide an estimate of the potential for soil organic matter management to reduce global yield gaps for two of the most important staple crops (maize and wheat) grown worldwide.
- Refining physical aspects of soil quality and soil health when exploring the effects of soil degradation and climate change on biomass production: an Italian case study
Refining physical aspects of soil quality and soil health when exploring the effects of soil degradation and climate change on biomass production: an Italian case study Antonello Bonfante, Fabio Terribile, and Johan Bouma SOIL, 5, 1-14, https://doi.org/10.5194/soil-5-1-2019, 2019 This study is restricted to soil physical aspects of soil quality and health with the objective to define procedures with worldwide rather than only regional applicability, reflecting modern developments in soil physical research and focusing on important questions regarding possible effects of soil degradation and climate change.
- Distribution of phosphorus fractions of different plant availability in
German forest soils and their relationship to common soil properties
and foliar P concentrations
Distribution of phosphorus fractions of different plant availability in German forest soils and their relationship to common soil properties and foliar P concentrations Jörg Niederberger, Martin Kohler, and Jürgen Bauhus SOIL Discuss., https//doi.org/10.5194/soil-2018-40,2018 Manuscript under review for SOIL (discussion: open, 3 comments) At German forest sites, many trees showed a deficiency in P nutrition. Half of soil P is contained in moderately-labile fractions, whereas stable and labile fractions contribute to ca. one quarter of total P. Soil properties such as pH, SOC and soil texture may be used to predict certain P pools in large forest soil inventories. Models using soil properties and soil P pools of different plant availability are not yet adequate to explain the P nutrition status in tree foliage.
- Assessment and quantification of marginal lands for biomass production in Europe using soil-quality indicators
Assessment and quantification of marginal lands for biomass production in Europe using soil-quality indicators Werner Gerwin, Frank Repmann, Spyridon Galatsidas, Despoina Vlachaki, Nikos Gounaris, Wibke Baumgarten, Christiane Volkmann, Dimitrios Keramitzis, Fotis Kiourtsis, and Dirk Freese SOIL, 4, 267-290, https://doi.org/10.5194/soil-4-267-2018, 2018 The need for biomass for energetic or material use is increasing parallel to the need to extend the production of food for a growing world population. This results in conflicts between both land use strategies. Use of marginal lands could solve this conflict, however, the understanding of marginal lands and the knowledge of their potentials are still not fully developed. We present an approach to assess land marginality based on soil quality and an estimation of land potentials all over Europe.
- Multi-source data integration for soil mapping using deep learning
Multi-source data integration for soil mapping using deep learning Alexandre M. J.-C. Wadoux, José Padarian, and Budiman Minasny SOIL Discuss., https//doi.org/10.5194/soil-2018-39,2018 Manuscript under review for SOIL (discussion: open, 2 comments) With the advances of new proximal soil sensing technologies, soil properties can be inferred by a variety of sensors, each having its distinct level of accuracy. This measurement error affects subsequent modelling and therefore must be integrated when calibrating a spatial prediction model. This paper introduces a deep learning model for contextual Digital Soil Mapping (DSM) using uncertain measurements of the soil property. The deep learning model, called Convolutional Neural Network (CNN), has the advantage that it uses as input a local representation of environmental covariates to leverage the spatial information contained in the vicinity of a location. Spatial non-linear relationships between covariate pixel values and measured soil properties are found by optimizing an objective function, which can be weighted with respect to a measurement error of soil observations. In addition, a single model can be trained to predict a soil property at different soil depths. This method is tested in mapping top- and subsoil organic carbon using laboratory analyzed and spectroscopically inferred measurements. Results show that CNNs significantly increased prediction accuracy as indicated by the coefficient of determination and concordance correlation coefficient, when compared to a conventional DSM technique. Deeper soil layer prediction error decreased, while preserving the interrelation between soil property and depths. The tests conducted using different window size of input covariates matrix to predict organic carbon suggest that CNN benefits from using local contextual information up to 260 to 360 metres. We conclude that CNN is a flexible, effective and promising model to predict soil properties at multiple depths while accounting for contextual covariates information and measurement error.