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Unpaved roads could be a significant source of dust emission. A common and effective practice to suppress this emission is the application of brine solution on these roads. However, this application could increase the risk of water source salinization in arid and semiarid regions, such as Israel. The general objective of the present study was to investigate the potential effects of treated wastewater (TWW), fresh water (FW), and brine applications as anti-dust emission solutions on water source salinization in these regions. A rainfall simulator experiment and a mass balance model were used for this goal. The TWW loaded the highest amounts of Cl, Na, and Ca+Mg on the unpaved roads, while the brine loaded higher amounts of Cl and Ca+Mg than the FW, and ~0 Na. In the rainfall experiment, runoff was not formed, and ~100% of the loaded amounts were leached downwards by rain, indicating a negligible salinization risk to surface water. We estimated that the average increases in the Cl concentrations in the modeled aquifer, following TWW, brine, and FW applications, were low: 1.2–1.6, 0.58–0.8, and 0.32–0.4 mg L−1, respectively. Thus, the solution selection for preventing dust emission should be based on the total cost of the solution application. [ABSTRACT FROM AUTHOR]

Excess soils from construction sites (waste soils) become a problem when exposed to soil erosion by water or wind. Understanding waste soil erodibility can contribute to its proper reuse for various surface applications. The general objective of the study was to provide a better understanding of the effects of soil properties on erodibility of waste soils excavated from various depths in a semiarid region under rainfall and wind erosive forces. Soil samples excavated from the topsoil (0–0.3 m) and subsoil layers (0.3–0.9 and > 1 m depths) were subjected to simulated rainfall and wind. Under rainfall erosive forces, the subsoils were more erodible than the topsoil, in contrast to the results obtained under wind erosive forces. Exchangeable sodium percentage was the main factor controlling soil erodibility ( K i ) under rainfall, and a significant logarithmic regression line was found between these two parameters. In addition, a significant, linear regression was found between K i and slaking values for the studied soil samples, suggesting that the former can be predicted from the latter. Soil erodibility under wind erosion force was controlled mainly by the dry aggregate characteristics (mean weight diameter and aggregate density): their higher values in the subsoil layers resulted in lower soil erodibility compared to the topsoil. [ABSTRACT FROM AUTHOR]

Dust storms are a common phenomenon in arid and semi-arid areas, and their impacts on both physical and human environments are of great interest. Number of studies have associated atmospheric PM pollution in urban environments with origin in natural soil/dust, but less evaluated the dust spatial patterns over a city. We aimed to analyze the spatial-temporal behavior of PM concentrations over the city of Beer Sheva, in southern Israel, where dust storms are quite frequent. PM data were recorded during the peak of each dust episode simultaneously in 23 predetermined fixed points around the city. Data were analyzed for both dust days and non-dust days (background). The database was constructed using Geographic Information System and includes distributions of PM that were derived using inverse distance weighted (IDW) interpolation. The results show that the daily averages of atmospheric PM10 concentrations during the background period are within a narrow range of 31 to 48 μg m-3 with low variations. During dust days however, the temporal variations are significant and can range from an hourly PM10 concentration of 100 μg m-3 to more than 1280 μg m-3 during strong storms. IDW analysis demonstrates that during the peak time of the storm the spatial variations in PM between locations in the city can reach 400 μg m-3. An analysis of site and storm contribution to total PM concentration revealed that higher concentrations are found in parts of the city that are proximal to dust sources. The results improve the understanding of the dynamics of natural PM and the dependence on wind direction. This may have implications for environmental and health outcomes. [ABSTRACT FROM AUTHOR]

Over the last decades, changes in dust storms characteristics have been observed in different parts of the world. The changing frequency of dust storms in the southeastern Mediterranean has led to growing concern regarding atmospheric PM 10 levels. A classic time series additive model was used in order to describe and evaluate the changes in PM 10 concentrations during dust storm days in different cities in Israel, which is located at the margins of the global dust belt. The analysis revealed variations in the number of dust events and PM 10 concentrations during 2001–2015. A significant increase in PM 10 concentrations was identified since 2009 in the arid city of Beer Sheva, southern Israel. Average PM 10 concentrations during dust days before 2009 were 406, 312, and 364 μg m −3 (median 337, 269,302) for Beer Sheva, Rehovot (central Israel) and Modi'in (eastern Israel), respectively. After 2009 the average concentrations in these cities during dust storms were 536, 466, and 428 μg m −3 (median 382, 335, 338), respectively. Regression analysis revealed associations between PM 10 variations and seasonality, wind speed, as well as relative humidity. The trends and periodicity are stronger in the southern part of Israel, where higher PM 10 concentrations are found. Since 2009 dust events became more extreme with much higher daily and hourly levels. The findings demonstrate that in the arid area variations of dust storms can be quantified easier through PM 10 levels over a relatively short time scale of several years. [ABSTRACT FROM AUTHOR]

Vegetation gap patterns in arid grasslands, such as the "fairy circles" of Namibia, are one of nature's greatest mysteries and subject to a lively debate on their origin. They are characterized by small-scale hexagonal ordering of circular bare-soil gaps that persists uniformly in the landscape scale to form a homogeneous distribution. Pattern-formation theory predicts that such highly ordered gap patterns should be found also in other water-limited systems across the globe, even if the mechanisms of their formation are different. Here we report that so far unknown fairy circles with the same spatial structure exist 10,000 km away from Namibia in the remote outback of Australia. Combining fieldwork, remote sensing, spatial pattern analysis, and process-based mathematical modeling, we demonstrate that these patterns emerge by self-organization, with no correlation with termite activity; the driving mechanism is a positive biomass- water feedback associated with water runoff and biomass-dependent infiltration rates. The remarkable match between the patterns of Australian and Namibian fairy circles and model results indicate that both patterns emerge from a nonuniform stationary instability, supporting a central universality principle of pattern-formation theory. Applied to the context of dryland vegetation, this principle predicts that different systems that go through the same instability type will show similar vegetation patterns even if the feedback mechanisms and resulting soil-water distributions are different, as we indeed found by comparing the Australian and the Namibian fairy-circle ecosystems. These results suggest that biomass-water feedbacks and resultant vegetation gap patterns are likely more common in remote drylands than is currently known. [ABSTRACT FROM AUTHOR]

Eolian (wind) erosion is a widespread process and a major form of soil degradation in arid and semi-arid regions. The present study examined eolian soil loss and changes in soil properties at a field scale, in response to different soil treatments in two rain-fed agricultural practices by short-term field experiments using a boundary-layer wind tunnel and soil properties analysis. Two practices with different soil treatments of mechanical tillage and stubble grazing intensities were applied in the fallow phase of the rotation (dry season). Mechanical tillage operations and stubble grazing intensities had immediate and direct effects on soil aggregation but not on the soil texture, and the contents of soil water, organic matter, and CaCO 3 . Higher erosion rates, measured as fluxes of total eolian sediment (TAS) and particulate matter <10 μm (PM 10 ), were recorded under mechanical tillage and grazing intensities compared with the undisturbed topsoil of the control plots. The erosion rates were higher in grazing plots than in tillage plots. The calculated soil fluxes in this study indicate potentially rapid soil degradation due to loss of fine particles. [ABSTRACT FROM AUTHOR]

Quantitative information on the contribution of dust storms to atmospheric PM10(particulate matter with an aerodynamic diameter ≤10 µm) levels is still lacking, especially in urban environments with close proximity to dust sources. The main objective of this study was to quantify the contribution of dust storms to PM10concentrations in a desert urban center, the city of Beer-Sheva, Negev, Israel, during the period of 2001–2012. Toward this end, a background value based on the “dust-free” season was used as a threshold value to identify potentially “dust days.” Subsequently, the net contribution of dust storms to PM10was assessed. During the study period, daily PM10concentrations ranged from 6 to over 2000 µg/m3. In each year, over 10% of the daily concentrations exceeded the calculated threshold (BVt) of 71 µg/m3. An average daily net contribution of dust to PM10of 122 µg/m3was calculated for the entire study period based on this background value. Furthermore, a dust storm intensity parameter (Ai) was used to analyze several storms with very high PM10contributions (hourly averages of 1000–5197 μg/m3). This analysis revealed that the strongest storms occurred mainly in the last 3 yr of the study. Finally, these findings indicate that this arid urban environment experiences high PM10levels whose origin lies in both local and regional dust events. [ABSTRACT FROM PUBLISHER]

Abstract: A single shrub in a widely spaced shrubby area acts as a roughness element and, therefore, it can affect the distribution of the rainfall received on the ground surface surrounding it. This paper focuses on such rainfall distribution on arid hillslopes and its eco-geomorphic implications. Relatively simple methods were used to measure the rainfall around shrubs growing in a small basin that is associated with a prevailing wind direction during rain events. There was a trend toward significantly reduced rainfall onto bare soil areas located on the leeward side, compared with that on other bare soil areas along the hillslope. This may alert to another potential cause for patchiness in the hydrological response of arid hillslope systems. [Copyright &y& Elsevier]

Abstract: Understanding the dynamic patch mosaic of topsoil moisture on arid hillsides has implications for understanding eco-geomorphic processes. The present study used high-resolution maps to investigate the spatial distribution of moisture in the topsoil on the shrub microenvironment scale, and its dynamics during the first days after rain events. These maps were acquired by a thermal infrared (TIR) method, based on close-range TIR imaging and on a model in which spatially consecutive TIR data are converted into soil moisture values. The main results show that, in addition to the general diminishing trend of topsoil moisture content, and in spite of the specific differences between the two research sites, there was, in both arid and semi-arid zones, a general spatio-temporal pattern of topsoil moisture in a shrub microenvironment during the first days after rainfall. This pattern is manifested in the presence of a changing moist patch under the shrub, and diminishing moisture content gradients, from the shrub center towards the bare soil that vary over space and time. An improved understanding of surface water resources is gained from investigations of the spatio-temporal patterns of soil moisture during and following rainfall events. [Copyright &y& Elsevier]