Satellite Mapping and Stabilization of the Aeolian deposits of QAFCO site 5/6

Aeolian processes produce vast areas of sand and dunes in the arid region and need monitoring since they are encroaching land and degrading infrastructures. In this study, we used the satellite data of ASTER and mineral indices namely quartz index (QI) and carbonate index (CI), and identified and discriminated the sand deposits, dunes, and associated rock formations that occurred in and around the QAFCO site 5/6, Qatar. The mapping of the area using high spatial resolution WorldView-2 satellite data confirmed the presence of sand deposits, dunes, and sand encroachments in the site. Our field studies validated the satellite data results. The grain size analyses of samples showed that the deposits have predominantly sand grains (81.3 to 99.81 %). The XRD analyses of samples identified the presence of quartz, calcite, dolomite, albite, and halite minerals. These are confirmed by geochemical analyses, which showed the high concentration of SiO2, Al2O3, CaO, MgO, Na2O, CO3, SO4, Cl, and B. In addition, the study of sand stabilization by bacteria method to stop the erosion at selected places of the site showed the applicability of the technique. All results allowed us to assess the implications of the deposits and encroachments at the industry site.

Experimental Study on Sand Stabilization Using Bio-Cementation with Wastepaper Fiber Integration

Recently, green materials and technologies have received considerable attention in geotechnical engineering. One of such techniques is microbially-induced carbonate precipitation (MICP). In the MICP process, CaCO3 is achieved bio-chemically within the soil, thus enhancing the strength and stiffness. The purpose of this study is to introduce the wastepaper fiber (WPF) onto the MICP (i) to study the mechanical properties of MICP-treated sand with varying WPF content (0–8%) and (ii) to assess the freeze–thaw (FT) durability of the treated samples. Findings revealed that the ductility of the treated samples increases with the increase in WPF addition, while the highest UCS is found with a small fiber addition. The results of CaCO3 content suggest that the WPF addition enhances the immobilization of the bacteria cells, thus yielding the precipitation content. However, shear wave velocity analysis indicates that a higher addition of WPF results in rapid deterioration of the samples when subjected to freeze–thaw cycles. Microscale analysis illuminates that fiber clusters replace the solid bonding at particle contacts, leading to reduced resistance to freeze–thaw damage. Overall, the study demonstrates that as a waste material, WPF could be sustainably reused in the bio-cementation.

Biology, parasitoid complex and potential distribution of saxaul's dominant defoliators, Teia dubia (Lepidoptera: Lymantriidae)

Natural enemies that impact pest populations must be understood in order to build integrated pest control strategies and to understand the most important aspects affecting pest dynamics. Haloxylon ammodendron (C. A. Mey.) Bunge is an important perennial plant species extensively used in sand stabilization and wind prevention in arid areas. This study aimed to determine the main defoliators that damage H. ammodendron and the parasitoid complex associated with them. Twelve species of defoliators were found in Northern Xinjiang, and Teia dubia (Tauscher) (Lepidoptera: Lymantriidae), Scrobipalpa sp. (Lepidoptera: Gelechiidae), and Eucharia festiva Hüfnagel (Lepidoptera: Arctiidae) were the dominant pests. T. dubia is the predominant defoliator with three generations a year. Northwest China, Central Asia, and the Mediterranean region are potentially suitable habitats for T. dubia in the world, while Xinjiang is the primary distribution area in China. Parasitoids belonging to seven species and four families were reared from the larvae of T. dubia, they were all endoparasitoids and koinobiont. Cotesia sp. (Hymenoptera: Braconidae) is the dominant parasitoid and prefer to parasitic in the 3rd–5th instar larvae. The present study provides the basis for understanding the species composition and natural enemies of lepidopteran defoliators. It will be an effective tool for the integrated pest management programs of H. ammodendron forest.

Acacia saligna (Port Jackson wattle).

A. saligna is a fast-growing, nitrogen-fixing large shrub or small tree from southwestern Western Australia. It coppices readily and is tolerant of calcareous, alkaline and saline soils in temperate climates. A. saligna is planted in North Africa, the Middle East and South America for fodder, fuelwood, sand stabilization and as a windbreak. In Australia it is most commonly used as an ornamental, but is being increasingly planted in agroforestry systems for fodder production and soil conservation.

Soil Erosion: Dust Control and Sand Stabilization

This Special Issue on soil erosion invites novel and original articles based on physical and chemical theories, field and laboratory experimental, soil analyses, and/or statistical and mathematical modeling that advance our knowledge on dust control and sand stabilization.