Search

Abstract Protecting and restoring the degraded arid lakes are globally urgent issues. We document a potential recovery of the dried salt-lake, Lop Nur called "the Sea of Death" which is located at the terminus of the largest inland basin in China, the Tarim River Basin. The changes and relationship of surface water with climate parameters and groundwater in the basin over the last 30 years are analyzed, by using satellite remote sensing and land data assimilation products. We find that with increased surface water in the basin, the groundwater level in Lop Nur began to show an obvious positive response in 2015; and the rate of decline of the groundwater level is slowing down. We argue that after a balance is achieved between regional groundwater recharge and evapotranspiration, the Lop Nur ecosystem will gradually recover. This study shows an encouraging case for the protection and restoration of degraded lakes in dryland regions around the world.

Rivers are the main supply sources in inland areas for human activities, but they are also regarded as the most susceptible water bodies to pollutants. Understanding the key factors influencing the chemical characteristic is the basis for water supply and public health concern. And it is helpful for the protection of surface water under the influence of human activities. To reveal the hydrochemical process of river water and the key factors affecting the chemical compositions, a total of 33 samples from rivers in Muling-Xingkai Plain are collected for principal component analysis and hydrochemical analysis. Results indicate that river water is characterized by the type of HCO3-Ca and mixed HCO3-Ca·Na. But some samples with relative high nitrate content have Cl− as the dominant anion. The natural sources of chemical ions in river water are silicate and carbonate minerals. The chemical fertilizers only slightly influence the chemical compositions of river water due to the retardation of black soil with weak permeability. The chemical compositions of river water in Muling river are significantly influenced by domestic sewage compared with that in Abuqin river and Qihulin river. The widespread thick black soils play a key roles in protecting the river quality and groundwater quality, and human activities only play a limited roles in determining the river quality in the Muling-Xingkai Plain. At present, the contents of major chemical ions in river water meet the irrigation standard. Although the irrigation with river water do not lead to the food safety issue, the government agencies should adopt adequate measures to control the indiscriminate discharge of domestic sewage and application of fertilizers for preventing the accumulation of pollutants in rivers. This study is beneficial to the efficient management of surface water resources in agricultural areas with similar geological conditions and hydrogeological conditions.

The origin and geochemical evolution of formation water trapped in continental shale of the Dameigou Formation in the Northern Qaidam Basin have been investigated for selecting unique signatures of formation water compared with shallow groundwater and conventional oilfield brines (COB). The formation water, which is trapped in a closed shale with no halite and sylvite in it, has a higher Cl/Br ratio (1183.43) than that of seawater (657.89). Furthermore, δ2H (--67‰) and δ18O (--8.1‰) values of the formation water lies near the local evaporation line. These suggest that the formation water originated from evaporated rainwater. The temperature (>120°C) of the Dameigou Formation and the vitrinite reflectance values (1.0-1.3%) of the shale indicate that thermochemical sulfate reduction (TSR) was responsible for the depletion of SO4 in the formation water. The increased CO2 concentration and Mg/Ca ratio in formation water leading by TSR caused kaolinization of plagioclase feldspar and dolomitization, respectively. The formation water depletion in Ca and HCO3 was caused mainly by calcitization. The Na/Ba ion exchange and dissolution of continental borate occurring in the shale-formation water system were vital to the geochemistry of trace elements in formation water. All these geochemical processes have given the formation water distinctive δ34S-H2S (25.9‰), 87Sr/86Sr ratio (0.713842), Ba/Ca ratio (2.60×10-2) and δ11B (1.1‰) signatures compared with COB in shallow groundwater. [ABSTRACT FROM AUTHOR]

This paper proposes a wideband dual-polarized magneto-electric dipole antenna composed of two pairs of vertical shorted patches and two pairs of horizontal double-layered planar dipoles. To achieve dual-polarization radiation, two orthogonal G-shaped stepped-impedance strip feed lines are designed to excite the antenna. The regions between the vertical shorted patches are loaded by dielectric materials to reduce the antenna profile. In addition, the antenna is backed with a rectangular cavityshaped reflector to improve radiation pattern stability and diminish back radiation. Experimental results demonstrate that the proposed antenna has obtained a wide impedance bandwidth of 57.1% from 1.5 to 2.7GHz and high port isolation of better than 30 dB within the bandwidth. The average antenna gain is about 9.7 dBi with a variation of below ±1.5 dB, and the radiation patterns are unidirectional, symmetric with low back radiation and low cross-polarization radiation across the entire operating band. [ABSTRACT FROM AUTHOR]