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  • 1
    Online Resource
    Online Resource
    MDPI AG ; 2018
    In:  Geosciences Vol. 8, No. 10 ( 2018-09-20), p. 356-
    In: Geosciences, MDPI AG, Vol. 8, No. 10 ( 2018-09-20), p. 356-
    Abstract: The effects of compaction on soil shrinkage behavior need to be considered for engineering long-term durable mineral liners of landfill capping systems. For this purpose, a new three-dimensional laser scanning device was coupled with a mathematical-empirical model to simultaneously determine the shrinkage behavior of a boulder marl (bm) and a marsh clay (mc). Therefore, both materials were precompacted in 200 soil cores (100 cm3) on the basis of the Proctor test results with five different degrees of compaction (bm1-bm5; mc1-mc5). Thus, the shrinkage behavior, intensity, and tendency were determined during a standardized drying experiment. The volume shrinkage index was used to describe the pore size dependent shrinkage tendency and was classified as high to very high (11.3–17.7%) for the marsh clay and medium (5.3–9.2%) for the boulder marl. Additionally, only the boulder marl (bm2), compacted up to 88% of Proctor density, could be installed as landfill bottom liner in drier locations if the local matric potentials did not exceed the previously highest observed drying range (i.e. values below −300 hPa), to avoid crack formation and generation.
    Type of Medium: Online Resource
    ISSN: 2076-3263
    Language: English
    Publisher: MDPI AG
    Publication Date: 2018
    detail.hit.zdb_id: 2655946-8
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  • 2
    Online Resource
    Online Resource
    MDPI AG ; 2018
    In:  Geosciences Vol. 8, No. 10 ( 2018-10-10), p. 372-
    In: Geosciences, MDPI AG, Vol. 8, No. 10 ( 2018-10-10), p. 372-
    Abstract: Mineral temporary capping systems of landfills are required to accomplish the long-term coverage prerequisites or to use them as a basis layer prior to later permanent sealing. Such a capping system for a municipal waste landfill in Rastorf (Northern Germany) was developed and tested for its sealing capability on the basis of observed and simulated water balance components for the period between 2008 and 2015, considering observed local weather data and complemented by the Hydraulic Evaluation of Landfill Performance (HELP 3.95 D) model. The modeling results of this case study could be improved by the correction of previously used global solar radiation data due to the consideration of exposure and inclination angle of landfill surface areas. The model could positively be validated by comparing observed and simulated outflow (surface runoff and lateral drainage) data with R2 values ranging between 0.95 and 0.99, as well as for the leachate rates with R2 values of 0.78–0.87. The statistical-empirical HELP model was found useful in predicting the leachate generation of a temporary landfill capping system for specific soil and site conditions, even if only a restricted set of observed data was available.
    Type of Medium: Online Resource
    ISSN: 2076-3263
    Language: English
    Publisher: MDPI AG
    Publication Date: 2018
    detail.hit.zdb_id: 2655946-8
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  • 3
    Online Resource
    Online Resource
    MDPI AG ; 2019
    In:  Soil Systems Vol. 3, No. 4 ( 2019-09-25), p. 63-
    In: Soil Systems, MDPI AG, Vol. 3, No. 4 ( 2019-09-25), p. 63-
    Abstract: Biochar impacts soil-water related processes such as infiltration and contributes to the hydrological response of catchments. The aim of this work is to determine the impact of wetting and drying conditions on the infiltration behavior of two biochar amendments and to validate the performance of three infiltration models: Kostiakov, Horton, and Philips. Two materials, sand and a sandy loam, were mixed with 0%, 2.5%, and 5% (by dry wt.) mango wood biochar produced at a highest heating rate of 600 °C and with a particle size of 〈 63 μm. A sequence of four wetting and drying cycles were simulated. In each cycle, infiltration was measured. We found that biochar addition decreased infiltration because the formation of narrower pores reduced infiltration capacity. The higher the biochar dosage, the more resilient the treatment became concerning the changes on the water infiltrated. Repetitive wetting and drying cycles resulted in a reconfiguration of structural pores affecting the transport of water and air. The infiltration models of Kostiakov and Horton could predict the infiltration dynamics in the amended materials, although they show some instabilities along the WD cycles.
    Type of Medium: Online Resource
    ISSN: 2571-8789
    Language: English
    Publisher: MDPI AG
    Publication Date: 2019
    detail.hit.zdb_id: 2932897-4
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  • 4
    In: Soil Systems, MDPI AG, Vol. 4, No. 3 ( 2020-07-28), p. 46-
    Abstract: The COVID-19 pandemic has disrupted the global food supply chain and exacerbated the problem of food and nutritional insecurity. Here we outline soil strategies to strengthen local food production systems, enhance their resilience, and create a circular economy focused on soil restoration through carbon sequestration, on-farm cycling of nutrients, minimizing environmental pollution, and contamination of food. Smart web-based geospatial decision support systems (S-DSSs) for land use planning and management is a useful tool for sustainable development. Forensic soil science can also contribute to cold case investigations, both in providing intelligence and evidence in court and in ascertaining the provenance and safety of food products. Soil can be used for the safe disposal of medical waste, but increased understanding is needed on the transfer of virus through pedosphere processes. Strengthening communication between soil scientists and policy makers and improving distance learning techniques are critical for the post-COVID restoration.
    Type of Medium: Online Resource
    ISSN: 2571-8789
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2932897-4
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  • 5
    In: Water, MDPI AG, Vol. 8, No. 10 ( 2016-09-27), p. 424-
    Abstract: Accurate simulation of soil water and heat transfer is critical to understand surface hydrology under cold conditions. Using an extended freezing code in HYDRUS-1D (freezing module), this study was conducted: (1) to evaluate the freezing module using field data collected in a grazed steppe of Inner Mongolia; and (2) to further simulate grazing effects on frozen soil hydrological processes. The experimental data consisted of soil water and temperature profiles measured during freeze-thaw cycles from 2005 to 2006 in two plots (ungrazed since 1979 (UG79) and winter grazing (WG)). To check the sensitivity of the freezing module, a model without a freezing scheme (normal module) was used for comparison. We found that while the normal module can only simulate soil water and heat transfer under unfrozen conditions, the freezing module can simulate well under both frozen and unfrozen conditions. The freezing module can reasonably compute water phase change and, therefore, substantially improved the simulation of the evolution of liquid water and temperature in frozen soil. It overestimated liquid water content during spring snowmelt and, thus, underestimated surface runoff from underlying frozen soil layers. Furthermore, the weak prediction of soil moisture at the WG site, compared with the UG79 site, might relate to the less than ideal parameterization of soil hydraulic properties. Our results confirmed that the freezing module was able to accurately predict behaviors of soil freezing and thawing, as well as the effects of land management. We suggest that detailed knowledge of the soil-atmosphere processes is needed to improve the surface runoff algorithm in the frozen soil module.
    Type of Medium: Online Resource
    ISSN: 2073-4441
    Language: English
    Publisher: MDPI AG
    Publication Date: 2016
    detail.hit.zdb_id: 2521238-2
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  • 6
    Online Resource
    Online Resource
    MDPI AG ; 2018
    In:  Sustainability Vol. 10, No. 11 ( 2018-11-02), p. 4025-
    In: Sustainability, MDPI AG, Vol. 10, No. 11 ( 2018-11-02), p. 4025-
    Abstract: The soil shrinkage behavior of mineral substrates needs to be considered for engineering long-term durable mineral liners of landfill capping systems. For this purpose, a novel three-dimensional laser scanning device was coupled with (a) a mathematical-empirical model and (b) in-situ tensiometer measurements as a combined approach to simultaneously determine the shrinkage behavior of a boulder marl, installed as top and bottom liner material at the Rastorf landfill (Northern Germany). The shrinkage behavior, intensity, and geometry were determined during a drying experiment with undisturbed soil cores (100 cm3) from two soil pits; the actual in-situ shrinkage was also determined in 0.2, 0.5, 0.8, and 1.0 m depth by pressure transducer tensiometer measurements during a four-year period. The volume shrinkage index was used to describe the pore size dependent shrinkage tendency and it was classified as low (4.9%) for the bottom liner. The in-situ matric potentials in the bottom liner ranged between −100 and −150 hPa, even during drier periods, thus, the previously highest observed drying range (pre-shrinkage stress) with values below −500 hPa and −1000 hPa was not exceeded. Therefore, the hydraulic stability of the bottom liner was given.
    Type of Medium: Online Resource
    ISSN: 2071-1050
    Language: English
    Publisher: MDPI AG
    Publication Date: 2018
    detail.hit.zdb_id: 2518383-7
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  • 7
    In: Agronomy, MDPI AG, Vol. 11, No. 10 ( 2021-10-13), p. 2052-
    Abstract: Soil degradation and water stress in Costa Rica challenge the production of highly sensitive crops. This work is aimed at evaluating the physical and chemical changes in sandy loam (SL) and a silt loam (SiL) soil when amended with bamboo biochar while estimating the enhancement of tomato productivity. Biochar, obtained from Guadua Angustifolia bamboo feedstock, was mixed into sieved bulk soil substrate from the topsoil, from Andosol and Umbrisol groups, at application rates of 1, 2.5, and 5% (dry mass). Physicochemical and morphological properties of biochar such as pH, hydrophobicity, scanning electron microscopy images, helium picnometry, specific surface area by the Brunauer–Emmett–Teller (BET) method, CHNS, and ash content were determined. Soil hydrophobicity, acidity, electrical conductivity, cation exchange capacity and water retention, available water content, and air capacity were analyzed for the amended soils. Tomato yield was quantified after a harvest period of two months. The admixture of biochar did not significantly increase soil cation exchange capacity but increased water retention in the range of available water content. Class A ( 〉 200 g) tomato yield increased 350% in the SL and 151% in the SiL. Class B (100–200 g) tomato yields increased 27% in the SL but decreased about 30% in the SiL. Tomato yield response seems attributable to variation of water retention capacity, available water content, and air capacity. These results support the use of adapted water management strategies for tomato production based on soil physical changes of biochar.
    Type of Medium: Online Resource
    ISSN: 2073-4395
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2607043-1
    SSG: 23
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  • 8
    Online Resource
    Online Resource
    MDPI AG ; 2018
    In:  Geosciences Vol. 9, No. 1 ( 2018-12-20), p. 1-
    In: Geosciences, MDPI AG, Vol. 9, No. 1 ( 2018-12-20), p. 1-
    Abstract: Mineral landfill liners require legally-fixed standards including a sufficiently-high available water capacity (AWC) and relatively low saturated hydraulic conductivity values (Ks). For testing locally available and potentially suitable materials with respect to these requirements, the soil hydraulic properties of boulder marl (bm) and marsh clay (mc) were investigated considering a defined compaction according to Proctor densities. Both materials were pre-compacted in 20 soil cores (100 cm3) each on the basis of the Proctor test results at five degrees of compaction (bm1–bm5; mc1–mc5) ranging between 1.67–2.07 g/cm3 for bm and 1.09–1.34 g/cm3 for mc. Additionally, unimodal and bimodal models were used to fit the soil water retention curve near saturation and changes in the pore size distribution (PSD). The structural peak of the PSD in the fraction of pore volume between −30 and −60 hPa was more pronounced on the dry side (bm1–2, mc1–2) than on the wet side of the Proctor curve (bm4–5, mc4–5). Therefore, the loss in structural pores can be attributed to an increasing dry bulk density for bm and an increasing gravimetric moisture content during Proctor test for mc. While the mc fulfils the legal standards with AWC values between 0.244–0.271 cm3/cm3, the Ks values for bm between 1.6 × 10−6 m/s and 3.8 × 10−7 m/s and for mc between 7.4 × 10−7 m/s and 1.2 × 10−7 m/s were up to two orders of magnitude higher than required. These results suggest that the suitability of both materials as landfill liner is restricted.
    Type of Medium: Online Resource
    ISSN: 2076-3263
    Language: English
    Publisher: MDPI AG
    Publication Date: 2018
    detail.hit.zdb_id: 2655946-8
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