Structural and hydrological alterations of soil due to addition of coal fly ash

Purpose: We tested the potential of using coal fly ash for improving the physical and hydrological characteristics of coarse and medium-textured agricultural soils. Materials and methods: Acidic (FWA) and alkaline (FNSW) fly ashes were used to amend a range of representative agricultural soils. In the first experiment, fly ash was applied to the top 10 cm of 1-m long intact cores of a sandy loam soil at rates of 0, 12, 36 or 108 Mg/ha and sown with canola; after harvest, bulk density (BD), aggregate stability and mean weight diameter (MWD) were measured on the soil. In the second experiment, we assessed water retention at field capacity (-300 kPa) and permanent wilting point (-1,500 kPa) for sandy and loamy soils amended with FNSW at 0.0-16% (w/w). The third experiment used rainfall simulation to assess erodibility of sandy and loamy soils mixed with FNSW at rates of 0, 5 or 20 Mg/ha. Results and discussion: In the first experiment, fly ash had no significant effect on MWD of the soil. The BD in the 0-10 cm layer (topsoil) was increased with addition of FWA, while FNSW applied at 108 Mg/ha reduced BD, relative to the control treatment. This was because FNSW had lower particle and bulk densities than FWA and the test soils. Ash addition increased macro-aggregation, significantly so in the 10-20 cm layer (subsurface layer), by reducing the percentages of micro-aggregates and silt + clay particles. Thus, macro-aggregation was positively correlated (p < 0.01) with MWD, but both were inversely correlated (p < 0.01) with micro-aggregates. In the second experiment, addition of fly ash enhanced plant water availability by increasing water retention at field capacity by threefold in the sandy soil and 1.5-fold in the loamy sand, but water retention at permanent wilting point was not affected. In Experiment 3, the addition of ash at 20 Mg/ha, but not at 5 Mg/ha, increased turbidity of runoff water from the amended soil due to the dispersal of fine particles by the impact of the simulated raindrops. Conclusions: Moderate rates of fly ash (<12 Mg/ha or ≤2% w/w) addition can improve aggregation and plant water availability in light to medium-textured soils. Soil applications thus provide a significant end-use for fly ash and can be a part of strategies for minimising environmental footprints from coal-fired power generation. Future studies are needed to further optimise application practices for long-term sustainability. © 2010 Her Majesty the Queen in Right of Australia as represented by the University of New England, Australia

Uncertainty and uncertainty propagation in soil mapping and modelling

In previous chapters, the use of geostatistical modelling for soil mapping was addressed. We learnt that one of the advantages of kriging is that it not only produces a map of predictions but that it also quantifies the uncertainty about the predictions, through the kriging standard deviation. In this chapter we will look into this in more detail. We will also examine another way to assess the accuracy of soil prediction maps, namely, through independent validation. This approach has the advantage that it is model-free and hence makes no assumptions about the structure of the spatial variation and relationships between the target soil property and covariates. Finally, we will examine how uncertainties in soil maps propagate through environmental models and spatial analyses. Throughout this chapter we will use the Allier data set and case study, Limagne rift valley, central France, to illustrate concepts and methods. We will only consider soil properties that are measured on a continuous-numerical scale. Many of the concepts presented can also be extended to categorical soil variables, but this is more complicated and beyond the scope of this chapter

First thorough identification of factors associated with Cd, Hg and Pb concentrations in mosses sampled in the European Surveys 1990, 1995, 2000 and 2005

The aim of this study was, for the first time ever, to thoroughly identify the factors influencing Cd, Hg and Pb concentrations in mosses sampled within the framework of the European Heavy Metals in Mosses Surveys 1990–2005. These investigations can be seen as a follow up of a previous study where only the moss data recorded in the survey 2005 was included in the analysis (Schröder et al. 2010). The analyses of this investigation give a complete overview on the statistical association of Cd, Hg and Pb concentrations in mosses and sampling site-specific and regional characteristics, encompassing data from 4661 (1990), 7301 (1995), 6764 (2000) and 5600 (2005) sampling sites across Europe. From the many metals monitored in the European moss surveys, Cd, Hg and Pb were used as examples, since only for these three metals deposition measurements are being recorded in the framework of the European Monitoring and Evaluation Programme (EMEP). As exemplary case studies revealed that other factors besides atmospheric deposition of metals influence the element concentrations in mosses, the moss datasets of the above mentioned surveys were analysed by means of bivariate statistics and decision tree analysis in order to identify factors influencing metal bioaccumulation. In the analyses we used the metadata recorded during the sampling as well as additional geodata on, e.g., depositions, emissions and land use. Bivariate Spearman correlation analyses showed the highest correlations between Cd and Pb concentrations in mosses and EMEP modelled total deposition data (0.62 ≤ rs ≤ 0.73). For Hg the correlations with all the tested factors were considerably lower (e.g. total deposition r s  ≤ 0.24). Decision tree analyses by means of Classification and Regression Trees (CART) identified the total deposition as the statistically most significant factor for the Cd and Pb concentrations in the mosses in all four monitoring campaigns. For Hg, the most significant factor in 1990 as identified by CART was the distance to the nearest Hg source recorded in the European Pollutant Emission Register, in 1995 and 2000 it was the analytical method, and in 2005 it was the sampled moss species. The strong correlations between the Cd and Pb concentrations in the mosses and the total deposition can be used to calculate deposition maps with a regression kriging approach on the basis of surface maps on the element concentrations in the mosse

Model of Post Fire Erosion Assessment Using RUSLE Method, GIS Tools and ESA Sentinel DATA

Soil erosion in fired areas is one of the main environmental problem involves degrading the quality of the soil and reducing the productivity of the affected lands. The aim of this work is to implement a procedure that analyzes the change detection of the potential soil eroded in a burned area, and discriminate the amount of potential soil loss. As part of the MESARIP project (in agreement with the Regional Civil Protection) in order to implement the analyses of soil erosion pre and post fire event, using Sentinel 2 data and with the RUSLE (Revised Universal Soil Loss Equation) method in a GIS open source environment, a graphical model has been developed. The application of the RUSLE requires a series of consequential spatial analysis elaborations and, according to this scheme, the model has been developed with the Graphical Modeler. QGIS contains in a single environment a multiplicity of tools and algorithms native to other open source GIS software, such as, for example, SAGA GIS and GRASS GIS. The user interface is very simple and requires basic and thematic input data such as DEM, MASK areas or vegetation indices etc. The advantages in the construction of the model can be identified in the standardization of map algebra operations and also in the speed of execution of the steps. Currently the model has been tested in some burned areas in 2019 located in the northern part of the Apulia Region and will be tested in operational mode during the 2020 summer season