- Geosciences, Vol. 8, Pages 232: Where She Blows! A Ten Year Dust Climatology of Western New South Wales Australia
Dust emissions contribute significantly to atmospheric processes impacting the functioning of various earth and human systems. The question is often asked “how much dust is acceptable?” From a land management perspective, the aim is to reduce the degradation effects of wind erosion over time. To do this, we need to know the range of dust activity over a long time period and to set a target that shows a reduction in dust activity. In this study, dust activity is described by the number of dust hours per July to June period (dust storm year, DSY). We used the DustWatch network of high resolution particulate matter less than 10 µm (PM10) instruments to characterise the dust climatology for a ten year period for western New South Wales (NSW), Australia. The ten year study period covered one of the driest and wettest periods in south-eastern Australia, providing confidence that we have measurements of extremes of dust (0 to 412 h/DSY), rainfall (98 to 967 mm/DSY), and ground cover (0 to 99% of area/DSY). The dust data are then compared to remotely sensed ground cover and measured rainfall data to develop targets across a rainfall gradient. Quantile regression was used to estimate the number of dust hours for a given DSY rainfall at 21 DustWatch Nodes (DWN). The 75th percentile is used to determine the target number of dust hours for a ten year average DSY. The monitoring network clearly identified locations of high dust activity and changes in dust and ground cover that are associated with rainfall. The dust hour targets for NSW indicated that for every 100 mm increase in DSY rainfall (between 250 and 650 mm) there is a 10 h decrease in dust hours. The dust target enables us to evaluate whether wind erosion is decreasing with time for sites with different rainfall.
- Geosciences, Vol. 8, Pages 231: Pollution Plume Development in the Primary Aquifer at the Atlantis Historical Solid Waste Disposal Site, South Africa
The monitoring of pollution plumes from municipal landfills is essential in order to control and, where necessary, remediate aquifer contamination. The Atlantis historical landfill was established in 1975 and was unlined as it preceded the promulgation of the Minimum Requirements by the Department of Water and Sanitation. As the underlying, unconfined sandy aquifer serves as a water supply source to the town of Atlantis, regular quarterly hydrochemical monitoring was carried out from 1989 to 1997, at irregular intervals until 2003, and resumed in 2015 when new, deep boreholes were drilled. Groundwater monitoring over nearly three decades provided valuable information on the nature of the chemical reactions that take place in the subsurface and the extent of transport of chemical constituents. Ammonium and organic carbon, which are subject to redox reactions, were lagging compared to chloride and sodium, which are transported advectively. The most recent data indicated the plume consisted mainly of salinity (electrical conductivity (EC) > 200 mS m−1) in the form of sodium, calcium, chloride and bicarbonate ions 350–400 m down-gradient of the landfill, and it is still expanding at a maximum rate of about 25 m a−1, with local deviations from the regional flow pattern. It also became evident that the plume migrated to greater depth as it was transported further from the waste pile. The breakthrough of contaminants being observed at different depths highlights the importance of suitably designed monitoring networks.
- Geosciences, Vol. 8, Pages 230: Rehabilitation of Aging Urban Water Systems: Strategic Thinking Required
This paper highlights the fundamental and invaluable role of water services in human settlements and community development. The paper aims at revealing the reasons behind aging infrastructure, the major challenge of the sector worldwide, and finding alternative strategies and means for resolving them. The authors argue that the problems of water services are largely related to management, institutions, organizations, and policies. In many ways, the requirement to see water services in a wider institutional framework is analogical to the proposed framework of Integrated Urban Water Management. The paper first explores the exceptionally long timeframe of water services management, followed by frameworks on core and non-core operations of water utilities in relation to the roles of major parties in municipal decision-making. For solving the major problems of water services both political and professional will is needed, educational programs are to be revised, and better rules of the game (institutions) are needed together with additional inputs on Research and Development activities.
- Geosciences, Vol. 8, Pages 229: Sulfur, Strontium, Carbon, and Oxygen Isotopes of Calcium Sulfate Deposits in Late Carboniferous Rocks of the Loei-Wang Saphung (LWS) Area, Loei Province, Thailand
Sulfate deposits of the Loei-Wang Saphung (LWS) area, northeastern Thailand, intercalated with carbonate and silicic clastic rock were analyzed for S, O, C, and Sr to determine the depositional environment, as well as the age of formation. Sulfate samples yielded average values of δ34S of 14.6‰, while the 87Sr/86Sr ratio of gypsum was 0.708282 and that of anhydrite was 0.708288. The carbonate layers yielded average δ18OPDB, and δ13C values of −12.5‰ and −0.1‰, respectively. Our results revealed that the LWS evaporite deposits were originally formed from seawater, and the relatively negative value of δ18O was a result of meteoric alteration during subaerial exposure of the sections. Comparing these isotopic values with the nearby Nakon Sawan sulfate deposits, the Sr isotopes showed slightly higher values with very mild variations. These isotopic values suggest that the LWS deposits were not affected by subsequent hydrothermal alteration by younger igneous dikes in this area. Therefore, some of these isotope signatures are considered to be primary features of the deposit, despite the fact that the deposit underwent anchizone to epizone metamorphism. The S and Sr isotope values support the depositional age of the LWS sulfate deposit in the Middle to Late Carboniferous.
- Geosciences, Vol. 8, Pages 228: One-Dimensional Nonlinear Seismic Response Analysis Using Strength-Controlled Constitutive Models: The Case of the Leaning Tower of Pisa’s Subsoil
The Leaning Tower of Pisa was built between 1173 and 1360 and began to lean at the beginning of its construction. Extensive investigations to reveal the causes of the tilting only began in the early 20th century. Although few earthquakes have been recorded, there is a renewed interest in the seismic behavior of the tower triggered by the availability of new data and technologies. This paper highlights the influence of using new strength-controlled constitutive models in case of 1D nonlinear response analysis. This is an aspect that has been poorly investigated. Most of the computer codes currently available for nonlinear seismic response analysis (SRA) of soil use constitutive models able to capture small-strain behavior, but the large-strain shear strength is left uncontrolled. This can significantly affect the assessment of a 1-D response analysis and the Leaning Tower’s subsoil can be useful for this study as it represents a well-documented and well-characterized site. After a geological and geotechnical description of the subsoil profile and a synthesis of available data, the seismic input is defined. One-dimensional SRAs were carried out by means of a computer code which considers an equivalent-linear soil modelling and two codes which assume nonlinear soil response and permit to use strength-controlled constitutive models. All the parameters were calibrated on the basis of the same soil data, therefore allowing for a direct comparison of the results.
- Assessing the impact of acid rain and forest harvest intensity with the HD-MINTEQ model – Soil chemistry of three Swedish conifer sites from 1880 to 2080
Assessing the impact of acid rain and forest harvest intensity with the HD-MINTEQ model – Soil chemistry of three Swedish conifer sites from 1880 to 2080 Eric McGivney, Salim Belyazid, Therese Zetterberg, Stefan Löfgren, and Jon Petter Gustafsson SOIL Discuss., https//doi.org/10.5194/soil-2018-17,2018 Manuscript under review for SOIL (discussion: open, 0 comments) Forest management may lead to long-term soil acidification due to the removal of base cations during harvest. By means of the HD-MINTEQ model, we compared the acidification effects of harvesting with the effects of historical acid rain at three forested sites in Sweden. The effects of harvesting were predicted to be much smaller than those resulting from acid deposition during the late 20th century. Soil weathering rates were affected differently depending on dissolved Al3+ and pH.
- Comment on "Soil organic stocks are systematically overestimated by misuse of the parameters bulk density and rock fragment content" by Poeplau et al. (2017)
Comment on "Soil organic stocks are systematically overestimated by misuse of the parameters bulk density and rock fragment content" by Poeplau et al. (2017) Eleanor Ursula Hobley, Brian Murphy, and Aaron Simmons SOIL, 4, 169-171, https://doi.org/10.5194/soil-4-169-2018, 2018 This research evaluates equations to calculate soil organic carbon (SOC) stocks. Although various equations exist for SOC stock calculations, we recommend using the simplest equation with THE lowest associated errors. Adjusting SOC stock calculations for rock content is essential. Using the mass proportion of rocks to do so minimizes error.
- Hot regions of labile and stable soil organic carbon in Germany – Spatial variability and driving factors
Hot regions of labile and stable soil organic carbon in Germany – Spatial variability and driving factors Cora Vos, Angélica Jaconi, Anna Jacobs, and Axel Don SOIL, 4, 153-167, https://doi.org/10.5194/soil-4-153-2018, 2018 Soil organic carbon sequestration can be facilitated by agricultural management, but its influence is not the same on all soil carbon pools. We assessed how soil organic carbon is distributed among C pools in Germany, identified factors influencing this distribution and identified regions with high vulnerability to C losses. Explanatory variables were soil texture, C / N ratio, soil C content and pH. For some regions, the drivers were linked to the land-use history as heathlands or peatlands.
- Separation of soil respiration: a site-specific comparison of partition methods
Separation of soil respiration: a site-specific comparison of partition methods Louis-Pierre Comeau, Derrick Y. F. Lai, Jane Jinglan Cui, and Jenny Farmer SOIL, 4, 141-152, https://doi.org/10.5194/soil-4-141-2018, 2018 To date, there are still many uncertainties and unknowns regarding the soil respiration partitioning procedures. This study compared the suitability and accuracy of five different respiration partitioning methods. A qualitative evaluation table of the partition methods with five performance parameters was produced. Overall, no systematically superior or inferior partition method was found and the combination of two or more methods optimizes assessment reliability.
- Mapping homogeneous spectral response zones in a soil profile
Mapping homogeneous spectral response zones in a soil profile Edward J. Jones and Alex B. McBratney SOIL Discuss., https//doi.org/10.5194/soil-2018-12,2018 Manuscript under review for SOIL (discussion: open, 1 comment) Variable soil moisture content is one of the main factors limiting field application of visible near-infrared spectroscopy. External parameter orthogonalisation of soil spectra was found to conserve intrinsic soil information under variable moisture conditions. k-means clustering of treated spectra yielded similar classifications under in situ, field moist (laboratory) and air-dried condition. Homogeneous spectral response zones were identified that corresponded with field observed horizons.