Land degradation affects more than 52 billion hectares of land around the world. This is caused to a large extent by anthropogenic activities such as land abandonment, mining activities, deforestation, and inadequate land use and management. Disturbance or insufficient rebuilding of the soil physicochemical and biological characteristics can modify the ecosystem functions and services. In the absence of appropriate restoration, soils and ecosystems would remain in a disturbed state or continue to decline. Therefore, restoration and rehabilitation of degraded soils is critical to create healthy and functional ecosystems that support essential functions and services.
In this session, we welcome contributions covering research conducted in this area of research describing experimental, observational, and theoretical studies. Topics of interest are (although not limited to) causes and impacts of land degradation and remedial actions and strategies for soil restoration and rehabilitation at local, regional or global scales.
vPICO presentations: Mon, 26 Apr
In a large-scale restoration project, we studied the spontaneous vegetation development after the elimination of landscape scars in a former military training area in Hortobágy National Park, Central Hungary. After the removal of approximately 40,000 unexploded ordnances the bomb-craters have been soil-filled, leaving large unvegetated surfaces on a total area of 4,000 hectares in 2017. These research settings provided a unique opportunity to study the effects of environmental heterogeneity on vegetation recovery in a study system, where soil salt content and micro-topography are the major drivers of vegetation patterns. Due to the mixing of soil layers, there were patches with extremely high salt content on the recovering surfaces and several red-listed halophyte plant species, established from the seed bank already in the first year after restoration. We found that the diversity of plant species was the largest in the first year. We detected a significant increase in the vegetation cover and the cover of perennial species from the first year to the second. In the subsequent years the recovery of the vegetation continued but slowed down from the second to the third year. By eliminating landscape scars, the restoration project was successful in increasing the area of alkaline grasslands at the landscape scale and providing grazing lands for local farmers.
How to cite: Valkó, O., Borza, S., Godó, L., Lukács, K., Kiss, R., Kelemen, A., Miglécz, T., Tóth, Á., and Deák, B.: Restoration of landscape scars in former military areas: vegetation recovery in relation to fine-scale environmental heterogeneity, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-667, https://doi.org/10.5194/egusphere-egu21-667, 2021.
From 1999 onwards, China has initiated a large-scale landscape restoration project on the Chinese Loess Plateau, which has had profound but variable impacts on the local ecosystem services supply. In this study, we evaluate the spatial and temporal dynamics in 11 ecosystem services in the Yan’an area on the Chinese Loess Plateau from 1990 to 2018 based on the InVEST model and statistical yearbook data. To consider trade-offs and synergies between ecosystem services, the concept of ecosystem service bundles was used to understand the dynamics of ecosystem services. A significant increase of fruit production, sediment retention, habitat quality, aesthetic landscape value as well as learning and inspiration value was found over time in Yan’an area, while a decrease of timber production and water yield was also observed. Synergistic relations were found between sediment retention, carbon sequestration, habitat quality and outdoor recreation, while trade-offs were observed between timber production and water yield. The majority of ecosystem services bundles of Yan’an area were transformed from having a focus on timber production to aesthetic landscape value. The dynamics of ecosystem services change by land restoration was discovered, to start with increasing regulating services at expense of provisioning services, cultural services exceeding regulating services and occupied the main proportion subsequently. The most obvious change was observed in 2000, coinciding with the start of large-scale restoration activities. The implementation of the large-scale restoration project is recognized as a key driving force inducing these changes. Based on the results, it is recommended that the Yan’an government pays attention to local water resource management and timber supply.
How to cite: Chen, H., Fleskens, L., Schild, J., Moolenaar, S., Wang, F., and Ritsema, C.: Using ecosystem service bundles to evaluate spatial and temporal impacts of large-scale landscape restoration on ecosystem services on the Chinese Loess Plateau, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1718, https://doi.org/10.5194/egusphere-egu21-1718, 2021.
If not carefully managed, use of saline and sodic irrigation waters, a common practice in dryland regions, has the potential to cause significant harm to soils. Application of saline and sodic irrigation waters can lead to reductions in hydraulic conductivity, Ks, the mechanisms of which (e.g., slaking, swelling, clay dispersion) have been the focus of a vast body of scientific literature. The rehabilitation process, by contrast, is far less understood. Despite experimental evidence showing a significant degree of irreversibility, traditionally models have treated the degradation and rehabilitation processes as reversible. We demonstrate how this assumption obfuscates our ability to analyze the risk of long-term degradation and to estimate the resources and time required to rehabilitate. We achieve this by using the SOTE model — a minimalistic model that can be used to study dynamics of soil water content, salinity, and sodicity, as driven by irrigation practices and climatic conditions. Crucially, SOTE also accounts for the feedback between changing salinity and sodicity and soil Ks. This feedback includes irreversible changes in hydraulic conductivity, such that a soil’s history of degradation and rehabilitation informs its future state. We compare SOTE to existing models, which do not include hysteresis in Ks, and demonstrate that SOTE predicts more gradual rehabilitation of degraded soils, in line with the limited experimental evidence that has examined this question. For the test case of a degraded soil in a typical Mediterranean climate, SOTE forecasts that rehabilitation requires 50% more time and water resources, in comparison to models without hysteresis. This difference underscores the need to limit the risk of potential degradation, which SOTE also shows increases by 50% when hysteresis is accounted for. A sensitivity analysis indicates that SOTE is most sensitive to parameters connected to soil texture. The sensitivity analysis further indicates that our results are robust -- under all ranges of parameter values SOTE continues to forecast greater time requirements for rehabilitation and increased risk of soil degradation.
How to cite: Kramer, I., Bayer, Y., and Mau, Y.: Rethinking Rehabilitation: Application of the SOTE model to soil rehabilitation following salinity and sodicity induced degradation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5085, https://doi.org/10.5194/egusphere-egu21-5085, 2021.
Given that mining sites, active or closed, represent almost 1 percent of Earths’ surface, the choice of adequate rehabilitation strategy is of crucial importance. In our previous work, we were examining the types of rehabilitation and biodiversity developed in consequence, and suggested that natural succession should be favoured whenever possible.
As advocated by IPBES, in its report of the second session of the plenary meeting (2012), indigenous and local knowledge should be valued and taken into account in decision-making processes, in order to stop the biodiversity loss. Yet, the decisions on rehabilitations are being taken by environmental professionals, without consulting with site managers. In this study, we were examining whether there is a local knowledge, which could be used when choosing the adequate rehabilitation technique. We were interested in how quarries and sand and gravel pits managers apprehend biodiversity, since they are the ones conducting actions impacting biodiversity. We were interested in their apprehension of their own actions and its consequences on biodiversity.
Managers of 46 quarries and sand and gravel pits were interviewed, on site, using Critical Incident Technique (Flanagan, 1954), in order to obtain examples of concrete situations showing their relationship with biodiversity as well as their degree of conscience on biodiversity issues. Every interview lasted about one hour and a half and consisted of two parts: the first where general questions were asked in the office for about 15 minutes and the second where the questions about the situations related to biodiversity were asked, during the walk around the site for better contextualization.
We analyzed the collected data using Grounded Theory (Glaser et al. 1967) which is a method used to analyze the field data (e.g. interviews), in order to obtain a theory that explains the underlying phenomenon. Often used in social sciences in order to understand the phenomena and identify the paradigms, this method was well adapted to reveal the causes and motivations of actions conducted by site managers.
Results of this study allowed us to comprehend the site managers as not just actors at the source of impact on biodiversity, but also as actors that are informed and that invest themselves in a relationship with nature. They perceive the value of biodiversity in quarries and gravel pits, conduct a lot of non-mandatory actions for biodiversity, during the life cycle of the site and are motivated to conduct additional measures in order to favor biodiversity. We discovered that there is a hidden expertise among site managers. For instance, they are capable of recognizing a lot of animal species present on site and even to predict the failure of certain rehabilitation techniques.
Following this conclusion, it seems unfortunate that the experience of site managers is not used when choosing the type of rehabilitation. A more participatory, interactive and more educational two-way process would seem much more appropriate for this type of actors who are very important for the implementation of biodiversity protection policies and who see themselves more proactive than reactive.
How to cite: Pavlovic, V.: Are we neglecting local knowledge while choosing rehabilitation strategy for mining sites?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6613, https://doi.org/10.5194/egusphere-egu21-6613, 2021.
Progressive loss of productivity and plant diversity is a major in global rangelands. In African rangelands ecosystems, this process is partly attributed to heavy and uncontrolled grazing by livestock and wildlife, leading to land degradation. Therefore, restoring such degraded rangelands is critical for enhancing ecosystem health and securing the livelihoods of millions of people. Active restoration strategies, e.g. reseeding using indigenous perennial grasses has been identified as a viable ecological solution for restoring degraded African rangelands. Grass species indigenous to African rangelands Cenchrus ciliaris L. (African foxtail grass), Eragrostis superba Peyr. (Maasai love grass), Enteropogon macrostachyus (Hochst. Ex A. Rich.) Monro ex Benth. (Bush rye grass), Chloris roxburghiana Schult. (Horsetail grass) and Chloris gayana Kunth. cv Boma (Rhodes grass) were established in a semi-arid rangeland in Africa under natural conditions to compare their morphoecological characteristics and suitability for use in ecological restoration. Biomass dry matter yields, plant densities, basal cover, seed production, tiller densities and plant height were measured. Chloris gayana cv Boma and E. superba produced significantly higher dry matter biomass yields and seed production than other species. High biomass and seed production demonstrate their suitability to support livestock production and replenish depleted soil seed banks, respectively. Enteropogon macrostachyus and C. ciliaris displayed significantly higher values for plant densities, tiller densities and basal cover, also a component of establishment and ecological restoration success. Chloris roxburghiana ranked lowest in all the measured morphoecological characteristics. This may be a strong indicator of ecological site-specific characteristic of C. roxburghiana. Successful restoration of degraded African semi-arid rangelands using indigenous grass reseeding can best be achieved through careful selection of grasses to take advantage of their specific morphoecological characteristics. This selection should primarily be informed by the intended use of the rangeland.
How to cite: Mganga, K.: Morphoecological characteristics of grasses used to restore degraded semi-arid African rangelands, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9909, https://doi.org/10.5194/egusphere-egu21-9909, 2021.
Redistribution of soil organic carbon (SOC) in response to soil erosion along slopes plays an important role in understanding the mechanisms of SOC’s spatial distribution and turnover. Consequently, SOC redistribution has been considered in many conceptual or mathematical models of soil carbon stability and storage. Vegetation restoration has been identified as an effective method to alleviate soil erosion on the Loess Plateau, however, little research has addressed vegetation restoration’s effect on the SOC redistribution processes, particularly SOC’s spatial distribution and stability. This study quantified the SOC stock and pool distribution on slopes along geomorphic gradients in naturally regenerating forests (NF) and an artificial black locust plantation (BP), and used a corn field as a control (CK). The following results were as follows: (1) Vegetation restoration, particularly NF, slowed the migration of SOC and reduced the heterogeneity of its distribution effectively. The topsoil SOC ratios of the sedimentary area to the stable area were 109%, 143%, and 210% for NF, the BP and CK, respectively; (2) Vegetation restoration decreased the loss of labile organic carbon by alleviating the loss of dissolved organic carbon (DOC) and easily oxidized organic carbon (EOC). The DOC/SOC in the BP and NF increased significantly, and were 13.14 and 17.57 times higher, respectively, than in the CK (p < 0.05), while the EOC/SOC in the BP and NF was slightly higher than in the CK. (3) A relevant schematic diagram of SOC cycle patterns and redistribution along the Loess slope was drawn under vegetation restoration. These results suggest that vegetation restoration in the Loess slope effectively alleviated the redistribution and spatial heterogeneity of SOC through reducing soil erosion. Thus, the effects of vegetation restoration on SOC redistribution should be pay more attention in regional carbon storage estimation, especially in the Loess gully regions.
Keywords: Vegetation Restoration, Soil Organic Carbon Redistribution, Loess Slope, Soil Erosion, Soil Organic Carbon Stability
How to cite: Liang, Y., Zha, T., Li, X., and Zhang, X.: Vegetation restoration alleviated the soil surface organic carbon redistribution in the hillslope scale on the Loess Plateau, China, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5994, https://doi.org/10.5194/egusphere-egu21-5994, 2021.
Despite the efforts to reducing residues derived from thermal power stations, as near as 70% of fly-ash and other wastes end up in landfills. Definitive landfill covers are generally limiting for native plant establishment as these materials lack the characteristics of functional soils. This could compromise the success of restoration efforts increasing the risk of erosion. As part of a restoration project, we tested the efficacy of different erosion control covers to enhance soil functions, including C and nutrient cycling, water regulation, and erosion control. First, the fly-ash was encapsulated and covered with a one-meter of sandy-clay sediment mixed with 20 cm pine bark compost. Five native tree species were planted in four plots considering different soil cover treatments (Hydro-mulch, Coconut fiber mulch, Seeded mixed grasses, and no-cover). These were established considering a complete block design with nine replicates for cover treatment. To elucidate what soil function responded more rapidly to these treatments, we measured chemical soil indicators (C, N, and P total and available pools, pH, EC, CEC), microbial (Biomass and C, N, P pools), and physical (bulk density, texture, and infiltration). All these parameters were measured at three sampling intervals (0-20, 20-40, and 60-80 cm) immediately after the plantation and a year later (n=117 per year). Also, we installed triplicated erosion plots for each cover to quantify which cover was more effective in reducing erosion and runoff. Overall, total carbon and nitrogen content increases were found after the first year (p=0.04 and p<0.001 respectively) at 20 to 40 cm.
Similarly, available nutrients such as NO₃⁻, NH₄₊ showed a significant decrease in the first two depth intervals (p<0.001). Available phosphorus also showed a net decline in the first two depth intervals (p=0.02 and p<0.001). The no-cover treatment showed significantly higher amounts of water runoff and soil erosion (p=0.04) than the other three treatments. No differences were found in runoff and erosion between hydro-mulch, coconut fiber mulch, and grass cover. Our results show that soil's chemical properties (i.e., nutrient pools and nutrient availability) are sensitive to different cover types and respond rapidly after one year of plantation with native species. On the other hand, significant changes in physical properties are not visible yet. The experiment also concludes that all tested soil covers effectively reduced runoff and erosion compared to the control. These covers should be implemented in the initial stages of the revegetation.
How to cite: Crovo, O., Montecino, F., Alvarez, E., and Aburto, F.: Effectiveness of erosion control covers on soil quality recovery, runoff, and sediment production after forest restoration in a fly-ash landfill, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13844, https://doi.org/10.5194/egusphere-egu21-13844, 2021.
Rehabilitated soils from post mining fields are considered to have poor soil structure, low nutrient content and microbial activity. Soil development during rehabilitation is a complex biogeochemical process influenced by the inherent properties of the substrate used for the rehabilitation. Besides disturbed soil properties, in Australia soil rehabilitation success is also influenced by climatic conditions like high evaporation rate which affects rebuilding of soil system functions. There are several studies looking into the development of soil properties post rehabilitation in temperate climates, however, the intertwined development of soil structure, quality and quantity of soil organic matter (SOM) after the rehabilitation under water stressed environment is not clear until now.
In this study, we used a space-for-time chronosequence approach in the rehabilitated open-cast mine site at Yallourn (Victoria, Australia) to elucidate the development of soil structure and soil organic matter after rehabilitation. We selected five different fields with increasing rehabilitation ages (2, 3, 10, 21 and 39 years) and two mature soils that are used as grazing land. In each field, we sampled 6 independent locations with stainless steel cylinders (100 cm3) at two depths of 0-4 cm and 10-14 cm. All samples were analysed for bulk density, organic carbon (OC) and total nitrogen (TN) concentration. Selected samples were wet sieved into four aggregate size classes of <63 µm, 63-200 µm, 200-630 µm and >630 µm. Each aggregate size class was characterized by OC and TN concentration. The chemical composition of the SOM of selected samples was characterized using solid-state 13C NMR spectroscopy.
The studied soils have a strong temporal dynamic and variability as determined for the soil properties bulk density and SOM stocks. Aggregate fractionation showed that large macroaggregates (>630 µm) were the most abundant size class fractions in each rehabilitation field, representing 95-75% of the total soil mass. SOM played an important role in the formation of large macroaggregates, where the highest contribution to total OC content was observed. It became evident that plant derived carbon had a decisive role in the structural formation, because O/N-alkyl-C and alkyl-C chemical shift regions represented the highest relative intensities throughout the chronosequence.
How to cite: Haberstok, T., Pihlap, E., Bucka, F., Klör, T., Baumgartl, T., and Kögel-Knabner, I.: Soil structural development in a rehabilitated open-cast mine site in south-east Australia, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8791, https://doi.org/10.5194/egusphere-egu21-8791, 2021.
Dryland areas are being seriously affected by degradation processes. The use of organic amendments in ecosystem restoration is an effective technique for accelerating soil regeneration processes in degraded drylands. The goal of this paper is to establish the effect of application of various organic amendments to degraded soil, on soil buffering capacity after 10 years. Buffering capacity is an important indicator, which is evidence of the overall condition of the soil ecosystem and influences a whole range of other soil properties, because buffering in soil is defined as the resistance of the soil to variations in pH. The experiment was carried out at the location called El Pinarillo in the Sierra de Tejeda, Almijara and Alhama Natural Park (southern Spain). The site is located at 470 m a.s.l., in the upper part of an alluvial fan (calcareous conglomerates). The experiment treatments were natural soil, bare soil, hydropolymers, pinus mulch, prescribed burnt, Sewage sludge. Application of hydrogel had the smallest effect on buffering capacity 10 years after application and manifested as just a slight decrease in soil buffering capacity while maintaining or improving other soil properties. The good buffering capacity of this variant also allows further work with the specific soil without greater risk of further degradation. Sludge was identified as the worst variant, whereas soil buffering capacity fell markedly, because sewage sludge may significantly inhibit microbial activity and decomposition of organic matter. This variant is not suitable for further use, because there is a risk of further soil degradation.
How to cite: Hueso González, P., Dvořáčková, H., Hladký, J., and Vlček, V.: Buffering Capacities in Mediterranean soils under different soil management, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9648, https://doi.org/10.5194/egusphere-egu21-9648, 2021.
The application of rock powder is an option to improve soil fertility while valorising the overburden material produced by industries. The “enhanced weathering” of silicate rock has also gained recent interest in the scientific community for its potential to mitigate climate change. However, the effect of rock powder on the soil physical properties remains unclear, especially under climate change (e.g., increasing drought events). Prior to any large scale application of rock powder, it is crucial to disentangle the potential effects of rock powder application on its environment. In a mesocosm experiment, we explored the effect of three rock powders on plant biomass, soil aggregation and organic carbon (OC) allocation within aggregates, in two soils with clayey and sandy textures, under regular watering or severe drought conditions. We demonstrate that the rock powder was the third factor after drought and soil texture significantly affecting the plant growth, resulting in a significant plant biomass decrease ranging from - 13 % to - 42 % compared with the control. We mainly attribute this effect to the increase of the already neutral soil pH, along with the release of excessive heavy metal amounts at a toxic range for the plant. Yet, we found that adding rock powder to the soil resulted in an increase of the relative amount of microaggregates in the soil by up to + 70 %, along with a re-distribution of OC within the fine fractions of the soil (up to + 32 % of OC in < 250 µm fractions). The new mineral-mineral and organo-mineral interactions promoted by the rock powder addition could potentially favour OC persistence in soil on the long term. With our results, we insist on the potential risks for plant growth associated to the application of rock powder when not handled properly. In addition to the current enthusiasm around the capacity of rock powder to enhance carbon sequestration in the inorganic form, we also encourage scientists to focus their research on its effect on soil structure properties and OC storage.
How to cite: Reifschneider, L., Eichinger, V. F., Pihlap, E., Garcia-Franco, N., Kühnel, A., Bucka, F., Kögel-Knabner, I., and Vidal, A.: Can we improve soil properties and plant biomass using rock powder as soil amendment?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4512, https://doi.org/10.5194/egusphere-egu21-4512, 2021.
Arsenic is a trace metalloid, potentially toxic for humans, animals and for plants. The problem of soil pollution with arsenic occurs in Poland only on a local scale, but in the Sudetes and in their foreland, there are several sites were arsenic was mined in the past. Particularly high concentrations of As in soils were confirmed in Złoty Stok, formerly the main European centre of arsenic industry. Decomposing forest litter as well as flooding can affect mobilization of As and other toxic elements, change their speciation in pore water and influence the toxicity to biota. This study examined the chemistry and ecotoxicity of pore water acquired from two soils that developed in a former As mining site: from the “Orchid dump” and from a nearby forest. Soils used in the experiment contained very high concentrations of As: 2020 and 19600 mg/kg. An unpolluted soil was used as a control. Soil samples were incubated in various moisture conditions (70% of water holding capacity and 100% flooding), in the presence and absence of organic matter introduced with forest litter collected from a beech stand. Soil pore water was collected three times (after 7, 21 and 90 days) with MacroRhizon suction samplers. Chemical analysis of pore water involved the measurements of concentrations of As and potentially toxic metals, including Mn and Fe, as well as the concentrations of P. Ecotoxicity of pore water was examined in two bioassays: THAMNOTOXKIT F and RAPIDTOXKIT F. The Thamnocephalus platyurus toxicity test is a 24h bioassay based on the mortality of the test organisms (freshwater crustaceans). The sublethal effects were determined using RAPIDOTOXKIT, based on ISO standard 2011. This procedure measures the feeding inhibition of the juveniles of T. platyurus. A very high toxicity to T. platyurus was confirmed in the pore water of the soil richer in As, where all the organisms died. High mortality of crustaceans > 83,33 % was found in the pore water of soil collected from the Orchid dump, in particular after a longer incubation period. The addition of beech litter, as well as soil flooding, caused an increased mortality of test organisms that reached 100%, regardless of the time of incubation. In the pore water of less polluted soil, collected from the forest site in Złoty Stok, an increased mortality of crustaceans was observed upon the addition of beech litter. The RAPIDOTOXKIT test turned out less sensitive to high concentrations of As and other toxic components present in soil pore water. The feeding inhibition did not correspond directly with the concentrations of As. However, in the case of samples with the highest As concentration (130 mg/L), found in pore water of the Orchid dump soil treated with beech litter and fully flooded, the feeding inhibition reached 100%.
This research was funded by the National Science Centre of Poland; Project No. 2016/21/B/ST10/02221
How to cite: Szopka, K., Gruss, I., Gruszka, D., Karczewska, A., Dradrach, A., and Gałka, B.: The effects of organic matter and flooding on the ecotoxicity of pore water in soils developed in the sites of historical arsenic mining: application of biological tests with crustacean zooplankton , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6573, https://doi.org/10.5194/egusphere-egu21-6573, 2021.
Reclamation measurements are commonly applied to mitigate the leaching of metal pollutants in order to reduce the risk for humans and the environment. Organic and/or inorganic amendments are often recommended to stabilize tailings and to reduce leaching of contaminants. In a recent microcosm percolation experiment (Thouin et al., 2019), the addition of a mining slurry called ochre and manure, either alone or in combination, drastically reduced the leaching of several metal pollutants, notably Pb. Nevertheless, the biogeochemical processes involved in the immobilization of metal pollutants remain unknown, preventing the management of this remediation technique from being optimized and its extension to other sites. To fill this gap, a multicomponent reactive model was developed to simulate and forecast the impact of amendments on the leaching of metal pollutants. This model accounts for the following biogeochemical processes: kinetically-controlled dissolution and precipitation reactions, sorption reactions (i.e. surface complexation reactions), water-gas interactions and microbially-driven redox reactions with an explicit microbial growth. For all treatments, simulations revealed that Pb reactivity followed dynamic patterns driven by watering steps. The decrease in Pb concentration in the leachates of amended tailings compared to untreated tailings was also accurately reproduced. In untreated tailings, Pb reactivity is mainly controlled by the dissolution of Pb-bearing mineral phases. These reactions were maintained in thermodynamic disequilibrium due to the renewal of pore solution at each watering step. In amended tailings, this pattern was strengthened as the iron oxides contributed by ochre maintained a low Pb concentration in pore solution by sorbing released Pb. Sorption reactions were enhanced by the increase in pH induced by the dissolution of calcium carbonate initially present in ochre. The latter reaction was partially counterbalanced in tailings amended with manure as organic matter provided sufficient energy to fuel microbial aerobic respiration, leading to the release of protons. Pb desorption was promoted by this pH drop. By providing a better understanding of the effect of amendment, this multicomponent reactive model is a powerful tool to optimize the reclamation of tailings, in order to limit contaminant transfer to the environment.
Thouin H. et al. (2019), Appl. Geochem. 111, 104438
How to cite: Mertz, S., Le Forestier, L., Bataillard, P., and Devau, N.: Leaching of trace metals (Pb, Zn) from contaminated tailings: New insight from a modelling approach, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2232, https://doi.org/10.5194/egusphere-egu21-2232, 2021.
Open-cut coal mining operations remove enormous quantities of overburden material inorder to access coal seam. Upon interaction with atmospheric conditions, this overburden material referred to as spoils from which salts are leached, possesses the risk of affecting surface and groundwater quality around the mine sites. Due to a distinct lack of field data on leachate rates and chemistry for full-scale spoil piles, studies have relied on geochemical testing at laboratory-scale experiments such as free-draining funnels and columns. While laboratory leaching techniques under a controlled environment are a general predictor of how spoil behaves upon weathering, there remain gaps in understanding the leachate rates taking into consideration actual particle size, flow rates, water content, temperature, and oxygen supply. This study proposes and assesses a new mesoscale approach for predicting salinity release from spoils that is designed to obtain data more relevant to the closure options under consideration. 5 coal mine spoils from 3 mines located in Queensland, Australia was sampled, characterised (physical, geochemical, and mineralogical), and were subjected to weathering at mesoscale (1-2 tonnes sample volume) leaching for 11 cycles under natural conditions. Results showed that soil-like spoils with significant pockets of less permeable clayey or silty material have the ability to retain and release solute slowly with time while rock-like spoils followed a steady decay rate. The mesoscale tests produced distinctive characteristic decay curves of salt release from typical soil-like and rock-like spoils and have been useful in the calibration of flow and moisture-dependent salt kinetic parameters. The mesocosm leaching approach developed as a part of this study was close to real-sized spoil conditions such that it mimicked the water/rock ratios, preferential flow paths, and governing solute transport processes.
How to cite: Jain, K. R., Edraki, M., and McIntyre, N.: Prediction of salt release from coal mine spoils at meso-scale, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13651, https://doi.org/10.5194/egusphere-egu21-13651, 2021.
Self-overgrowing recovery of disturbed soils is one of important processes in reclamation of disturbed soils. Different types of anthropogenic disturbances followed by variety of soil types and their genesis leads to different bacterial communities, envolved in reclamation processes. Here we describe regional self-overgrowing soils in two location (Novgorod region, Northwest Russia). We analyse top level of industrial disturbed soils after coil mining (spoil tips with extremely low pH, and overburden soil) and sand quarry dumps followed by local undisturbed soils.
We perform 16s amplicone sequencind (v4-region) by Illumina MiSEQ and chemical routine analysis (pH, C, N and other). We provide alpha- and beta-diversity analysis, followed by CCA and analysis of differential abundance of taxa.
Sand quarry dumps and regional soils looks common on phyla level, and represent common soil phyla like Proteobacteria, Actinobacteria and Verrucomicrobia. Alpha-diversity metrics aslo are similar, despite difference in beta-diversity. Overburden soil and soil from spot tips, by contrast, is very different even in phylum level. Main intermediants here are Actinobacteria, Chloroflexi и Nitrospirae. Also they show extremely low alpha-diversity metrics.
This work was supported by RSF 17-16-01030, «Dynamics of soil biota in chronoseries of post-technogenic landscapes: analysis of soil-ecological efficiency of ecosystem restoration processes»
How to cite: Zverev, A., Kimeklis, A., Gladkov, G., Kichko, A., Andronov, E., and Abakumov, E.: Microbiological description of self-overgrowing spoil heaps and sand quarries in Nordwest Russia, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2086, https://doi.org/10.5194/egusphere-egu21-2086, 2021.
Australia faced the most extreme and prolonged fire season in 2019-2020, resulting in tragic habitat loss for many threatened species and the destruction of many ecological communities. Newnes Plateau Shrub Swamps are peatlands located in the upper Blue Mountains region of New South Wales, Australia. These ecosystems perform many important ecological functions while absorbing and filtering water and releasing it slowly back to the environment. Their functions are related to the control of peak flow events, water purification and the harboring of many threatened plant and animal species. Despite their ecological importance, the area has been intensively degraded through longwall mining processes, resulting in the lowering and loss of water tables in the area. In December 2019 these impacts were compounded by an intense prolonged drought period and extensive wildfire. While the effects of these combined factors on the vegetation have been analysed and revealed remarkable negative impacts in the swamps under mining pressures, the effects on the soil microbial communities and related soil functions have not yet been studied. To investigate both drivers (fire and mining activities), we selected three mined swamps and three unmined swamps to assess their soil microbial composition and diversity through Next Generation Sequencing, and to characterise the soil chemical composition. At each site, we collected samples considering three treatments, one in the swamp valley fill and two at two different heights of the swamp valley margin, focusing on the soil close to specific groups of plants (e.g. sedges and shrubs). For each site and treatment, three soil samples (~ 10 m from each other) of 10x10 cm and ~ 3 to 5 cm of depth were collected using a trowel. We aim to build 16S rRNA gene libraries and co-relate them with the soil chemical variables, to assess the impact on these microbial communities and their possible use as environmental indicators and basis for future applied initiatives in conservation and restoration.
How to cite: Machado de Lima, N., Thomsen, A., Ooi, M., and Muñoz-Rojas, M.: Bushfire impacts on a threatened swamp ecosystem: responses of the soil microbial communities and restoration, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3778, https://doi.org/10.5194/egusphere-egu21-3778, 2021.
Nowadays, land use change and the impacts of climate change are accelerating land degradation processes in drylands. These regions occupy around 40% of the Earth land’s surface and their extension is likely to represent around 45% by 2050. Biocrusts (complex communities formed by bacteria, cyanobacteria, microalgae, fungi, lichens and mosses which live in the uppermost layer of soil and can cover up to 70% of the interplant areas) play a decisive role in soil stabilization and fertility in these regions, so that they have been proposed as restoration agents in degraded dryland sites, where water scarcity and the harsh environmental conditions can hinder traditional restoration based on the use of vegetation establishment. Within the different biocrust-forming organisms, the use of cyanobacteria as a biotechnological tool to combat soil degradation, is gaining increasing importance. Cyanobacteria are the pioneer colonizers of terrestrial ecosystems, they are able to resist extreme environmental conditions, i.e. high temperatures, prolonged UV radiation and nutrients scarcity. At the same time, they improve physical-chemical properties of the soil by fixing carbon and many species also the atmospheric nitrogen and by producing exopolysaccharides that strongly increase soil stability and eventually creating a more favorable environment for colonization by other organisms. Despite several laboratory studies demonstrate the effectiveness of inoculating soil with cyanobacteria and their effect in increasing soil carbon and nutrient content, few field studies are available and many of them show a limited success probably because of the harsh environmental conditions that hamper an optimal growth. In the present work, soils collected from different ecosystems in SE Spain were inoculated with a consortium of four native cyanobacteria species: Nostoc comune, Trichocoleus desertorum, Tolypothrix distorta and Leptolyngbia sp., and different techniques to reduce abiotic stresses were tested in outdoors conditions: 1) cyanobacteria + soil covered with a mesh made of Stipa tenacissima, 2) cyanobacteria+ Plantago-based stabilizer amendment, and 3) cyanobacteria + sewage sludge (incorporated as an organic amendment) . The application of plant-based ameliorating strategies resulted in a higher chlorophyll a content, which reflects an improvement of cyanobacterial growth compared to the inoculation lacking the application of ameliorating techniques. The soil albedo also decreased due to surface darkening, thus also indicating a higher cyanobacterial growth in these treatments. Wind tunnel experiments also demonstrated a lower susceptibility to wind erosion in the cyanobacteria-inoculated soils combined with application of the plant mesh or the Plantago amendment. These results highlight the importance of using plant-based amelioration techniques to reduce abiotic stresses, especially in the early stages of soil colonization after cyanobacteria inoculation. Regarding the use of sewage sludge, it was demonstrated that their application at low doses improved cyanobacteria growth, which was reflected in an increase in chlorophyll a content as well as in a significant increase of aggregate stability and reduced soil susceptibility to wind erosion. This study shows promising results to enhance cyanobacterial growth and prevent cyanobacteria inoculum loss under natural conditions. Ongoing experiments will evaluate the effectiveness of these strategies under field conditions.
How to cite: Maggioli, L., Alameda, A., Román, J. R., Chamizo, S., Pagli, C., Roncero-Ramos, B., and Cantón, Y.: Innovative techniques to improve cyanobacterial survival and growth in inoculated dryland soils, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15907, https://doi.org/10.5194/egusphere-egu21-15907, 2021.
Seed-based ecosystem restoration has huge potential to restore degraded lands but currently less than 10 % of directly sown seeds successfully establish in drylands. Soil microbial communities are important for improving plant establishment in degraded land. However, current methods such as soil translocation can potentially disturb the donor site. In this study, we investigated a novel non-destructive method for improving seedling growth of native plants used in restoration through seed-soil-microbial pelleting. We assessed seedling emergence and survival of Triodia epactia and Acacia inaequilatera seeds inoculated with whole soil bacteria and cyanobacteria consortia retrieved and isolated from a pristine ecosystem. A field experiment was set-up in a 35m x 40m purpose-built rain exclusion shelter that contained reconstructed soil profiles typically encountered in mine rehabilitation programs of Australia’s arid north-west. We hypothesized that inoculated seed-soil pellets would improve seedling emergence and survival of these species. After three weeks of planting, seedling emergence in microbially inoculated Acacia inaequilatera and Triodia epactia were 48% and 55% higher than non-inoculated seeds in bacteria and cyanobacteria, respectively. We also tested whether the use of cyanobacteria consortia as inocula promoted higher seedling emergence over whole soil bacteria. We found that there was no significant difference in seedling emergence between the microbial taxa. We show that, improving the diversity of soil microorganisms improves seedling emergence and the seed-soil pellet method used is viable to improve seed-based restoration outcomes.
Key words: Seed-based restoration, microbial community, cyanobacteria, bacteria community, seedling emergence.
How to cite: Dadzie, F., Moles, A., Erickson, T., and Munoz-Rojas, M.: Native bacteria and cyanobacteria consortia improve seedling emergence and establishment in dryland restoration, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10412, https://doi.org/10.5194/egusphere-egu21-10412, 2021.
Arid and semi-arid (from hereafter dryland) ecosystems cover 70% of Australia, with climate change set to increase this area through desertification. Increased temperatures and reduced water availability are compounded through agricultural overgrazing. This degradation and habitat loss has led to biodiversity loss which disrupts the biogeochemical cycles that maintain these environments, creating a negative feedback loop, and making restoration efforts largely unsuccessful. With soil microbes being important drivers in dryland systems, understanding how different stressors impact the soil biome is needed to improve conservation and restoration efforts and promote resilience and resistance to climate change. Particularly lacking is understanding of these interactions over time.
Fowlers Gap Research Station is the only research station in the arid zone of Australia and was a working sheep station until 2019. Due to agricultural overgrazing the site is largely degraded however exclusion zones have been set up on the property ranging in time from 3 years to 40 years. These exclusion zones provide a powerful comparison for the impact of soil degradation on drylands. To investigate the impact of overgrazing on the soil biodiversity and ecosystem functions, we selected three of the exclusion zones paired with three degraded sites directly outside of the exclusion zone to assess their microbial composition and functional diversity, along with soil physicochemical properties. We aim to build 16S rRNA gene libraries and co-relate them with the soil chemical variables, to assess the impact of overgrazing on these microbial communities and the ecosystem functions they provide. This knowledge can be used to improve monitoring of conservation and restoration initiatives by providing environmental indicators for soil health over time.
How to cite: Stewart, J., Machado de Lima, N., Kingsford, R., and Muñoz-Rojas, M.: Soil microbial responses to passive restoration strategies in drylands: a temporal comparison of soil biodiversity and ecosystem function, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16398, https://doi.org/10.5194/egusphere-egu21-16398, 2021.
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