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.
Subject(s)
Groundwater , Lakes , Ecosystem , Water , Rivers , Water Supply , China , Environmental MonitoringABSTRACT
The source characterization of nitrate (NO3-) in groundwater of Muling-Xingkai Plain (MXP) and the influence of NO3- on the water environment were studied by hydrogeochemical and multivariate statistical analysis. A total of 164 groundwater samples were collected, and the samples were classified into three clusters by using hierarchical cluster analysis. Cluster 1 (C1), accounting for 13% of total samples, was mainly located in local residential zones where the top soils were the medium-textured sediments. Cluster 2 (C2) and cluster 3 (C3) were mainly located in farmlands and residential zones where the clay sediments were overlaying the aquifers. The soil media covering the aquifers was an important factor controlling the concentration of NO3- in groundwater, which determined the infiltration rate of wastewater and the redox environment of aquifers. Only the samples in C1 exceeded the WTO standards for NO3- (50 mg/L), and the samples in C2 and C3 had low NO3- concentration (less than 10 mg/L). The excessive NO3- in groundwater was observed in the shallow groundwater under local residential zones, and it was closely related to the anthropogenic activities since the 1950s. The domestic sewage was responsible for the elevated NO3- contents in the MXP. Then, it was still necessary to construct the sewage disposal system in rural areas to further protect the groundwater resource to avoid the formation of extensive nitrogen pollution. At present, NO3- in the groundwater mainly shows a fertilizer and natural rainwater origin and is not demonstrating the significant deterioration of groundwater qualities and water environment.
Subject(s)
Groundwater , Water Pollutants, Chemical/analysis , China , Environmental Monitoring , Nitrates/analysisABSTRACT
The internal fixation using metal bone plate is one of common method for the clinical treatment of fracture, it plays a role in fixation, protection and supporting of the fractured bone segments, but it also suffers high failure rates in clinical practice. This article reviewed the commonly used methods of failure analysis of bone plate, and described the research results of the failure analysis of bone plate in detail. The fatigue fracture of bone plate caused by stress concentration is the common fracture pattern. In addition, the article summarized the performance optimizations according to the cause of failure, then discussed its future development trends.
Subject(s)
Bone Plates , Fracture Fixation, Internal , Biomechanical Phenomena , Fractures, Bone , Humans , MetalsABSTRACT
Most of the shale gas production in northwest China is from continental shale. Identifying hydrogeochemical and isotopic indicators of toxic hydraulic fracturing flowback fluids (HFFF) has great significance in assessing the safety of drinking water from shallow groundwater and streamwater. Hydrogeochemical and isotopic data for HFFF from the Dameigou shale formations (Cl/Br ratio (1.81 × 10-4-6.52 × 10-4), Ba/Sr (>0.2), δ11B (-10-1), and εSWSr (56-65, where εSWSr is the deviation of the 87Sr/86Sr ratio from that of seawater in parts per 104)) were distinct from data for the background saline shallow groundwater and streamwater before fracturing. Mixing models indicated that inorganic elemental signatures (Br/Cl, Ba/Sr) and isotopic fingerprints (δ11B, εSWSr) can be used to distinguish between HFFF and conventional oil-field brine in shallow groundwater and streamwater. These diagnostic indicators were applied to identify potential releases of HFFF into shallow groundwater and streamwater during fracturing, flowback and storage. The monitored time series data for shallow groundwater and streamwater exhibit no clear trends along mixing curves toward the HFFF end member, indicating that there is no detectable release occurring at present.
Subject(s)
Groundwater , Hydraulic Fracking , Natural Gas , China , Rivers , Water , Water Pollutants, ChemicalABSTRACT
We demonstrated a real-time monitoring of live cells upon laminar shear stress stimulation via surface plasmon resonance (SPR) in gold nanoslit array. A large-area gold nanostructure consisted of 500-nm-period nanoslits was fabricated on a plastic film using the thermal-annealed template-stripping method. The SPR in the gold nanoslit array provides high surface sensitivity to monitor cell adhesion changes near the sensor surface. The human non-small cell lung cancer (CL1-0), human lung fibroblast (MRC-5), and human dermal fibroblast (Hs68) were cultured on the gold nanoslits and their dynamic responses to laminar shear stress were measured under different stress magnitudes from 0 to 30 dyne/cm(2). Cell adhesion was increased in CL1-0 under shear flow stimulation. No adhesion recovery was observed after stopping the flow. On the other hand, MRC-5 and Hs68 decreased adhesion and recovered from the shear stress. The degree of recovery was around 70% for MRC-5. This device provides dynamic study and early detection of cell adhesion changes under shear flow conditions.
