Artificial recharge engineering has been widely used to solve the water resource crisis. However, there are still some safety hazards regarding reclaimed water quality. Here, chlorinated secondary effluent (SE) was injected into saturated porous media composed of high–purity quartz sands. The column experiment was conducted and modeled through a developed numerical model to predict the evolution of physical clogging. Some representative inorganic and organic indicators were measured both at different times and in different column sections. The study showed that the relative hydraulic conductivity (K/K0) decreased significantly by approximately 63.5% in 40 h. Especially for the first 3 cm of the column, the clogging was the most serious, with a decrease of approximately 85.8%. The porous media has a certain degree of filtration effect on turbidity, TOC, protein (Pr) and polysaccharide (PS) but has slight removal for other water quality indicators. Pr is the main component of the intercepted TOC, and its content is higher than that of Ps. Moreover, the inorganic and organic parameter variations along the column further verified that the organic floc particles were mainly retained in the first 3 cm. The 3D excitation/emission matrix (3DEEM) fluorescence spectra illustrated that the humic acids and fulvic acids were easy to release and that their injection may be harmful to groundwater quality. The study will lay a theoretical foundation and provide a guiding scheme for optimizing China’s reclaimed water reuse technology, ensuring the safety of reclaimed water quality.
Polymer nanocomposites have drawn a lot of attention both from the academic and industrial research in the last decades, thanks to their remarkable mechanical and rheological properties as compared to pure polymers. In particular, they may display reinforcement for moderate volume fractions, and several non linear effects that appear for small deformation amplitudes. In spite of decades of research, the relation between nanocomposites structure and rheology is far from being understood. Atomistic simulations can give a detailed view of the interplay between polymer chains dynamics and fillers at a local scale. However, it is much more difficult to address the properties emerging at a mesoscopic scale, for instance, to simulate a large number of aggregates in an entangled polymeric matrix remains out of reach. In this work, we build a mesoscopic model to simulate the rheology of polymer nanocomposites with a simple fluid and an entangled polymer matrix, by using the Brownian dynamics and the generalized Langevin dynamics, respectively. In both cases, the motion of the polymer chains is not explicitly described and its effect on the filler dynamics is averaged out. Using this model, we quantitatively determine the influences of the filler type, the filler volume fraction, size and morphology on the rheology of the model composite. Of particular interest is the case of fractal-like aggregates, which may be flexible or rigid. We demonstrate that model aggregates display significant reinforcement, which increases with the aggregate size, aggregate rigidity, filler volume fraction and polydispersity. Long relaxation times are also evidenced, which are related to the slow rotation of the aggregates. The well-known Payne effect, associated to the nonlinear response of the dynamic moduli with the shear deformation amplitude, is also seen in our model composites. We relate the behavior of microscopic filler to the macroscopic properties of the composite
The ENE‐striking Chagan Obo shear zone in central Inner Mongolia is critical to constrain the termination of convergence between the North China‐Mongolia and Siberia continents. We recognized three ENE‐striking zones with strong deformation in the Permian biotite monzogranite within the shear zone and investigated the structural and kinematic characteristics. The strong deformation zones developed dense ENE‐striking and NNW‐dipping foliations. The widespread shear sense indicators such as S‐C foliations, mica fish, σ‐type, structures, and typical tight‐to‐isoclinal asymmetric folds show top‐to‐the‐SSE thrusting through NNW–SSE compression. Two 40 Ar‐ 39 Ar ages of muscovites from the muscovite quartz schists in this shear zone show 144.1 ± 1.2 Ma and 142.1 ± 0.9 Ma, respectively, providing the peak compression to be Early Cretaceous (144–142 Ma). Combined with the regional syn‐/post‐collisional magmatic rocks (166–155 Ma) related to the closure of the Mongol‐Okhotsk Ocean, this shear zone's ages (144–142 Ma) suggest that the continental convergence between the North China‐Mongolia and Siberia continents lasted from Late Jurassic to Early Cretaceous. The Early Cretaceous shoshonitic volcanism (137–133 Ma) and rift basins in this region indicate the onset of orogenic collapse in the eastern Central Asian Orogenic Belt.
A series single-pass compression tests of HRB400 slab under the circumstances of different deformation temperature and deformation rate are carried out with Gleeble-1500D thermal simulation testing machine. The experimental results shows as follows. The true stress-true strain curves of the compression process are got from the tests. The state activation energy is 353.542kJ/mol and a mathematical model of high-temperature rheological stress is established. The calculated results by the rheological model are consistent with the experiments.
Based on the law of conservation of energy and heat flow data in continental China, the upper limit of heat production for the crust beneath continental China is determined as 1.3μWm-3. Then, using the data of the heat flow and helium isotopic composition of underground fluids, the heat productions of various tectonic units in the crust of continental China are estimated to be in the range of 0.58-1.12μWm-3 with a median of 0.85μWm-3, and the corresponding U, Th and K abundances are in the ranges of 0.83-1.76μg/g, 3.16-6.69μg/g and 1.0%-2.12% respectively. These data indicate that the abundances of the radioactive elements U, Th and K in continental crust of China are notably higher than those in the Archean crust, suggesting that the components of continental crust of China are highly evolved. In addition, the crustal composition of continental China exhibits significant lateral heterogeneity. The crust beneath eastern China is enriched in highly incompatible elements such as U, Th and K relative to that beneath western China, and the crust beneath fold belts is enriched in U, Th and K relative to that beneath cratonic areas. It is inferred on the basis of a positive correlation between the SiO2 content and heat production of continental crust that the crust beneath eastern China and fold belts are more felsic than beneath western China and cratons. This regional variation is consistent with the results of inference from the seismic wave velocity data in China. According to the fact that the seismic wave velocity and heat production range of the crust of continental China are lower than the global average values, combined with a comparison with the global crustal composition models published by previous studies, it is deduced that the abundances of highly incompatible elements such as U, Th and K in continental crust are overestimated in the average composition models of global continent crust constructed by Rudnick and Fountain (1995), Rudnick and Gao (2003), Weaver and Tarney (1984), Shaw et al. (1986) and Wedepohl (1995).
Abstract Recently, a huge ultrahigh‐pressure (UHP) metamorphic belt of oceanic‐type has been recognized in southwestern (SW) Tianshan, China. Petrological studies show that the UHP metamorphic rocks of SW Tianshan orogenic belt include mafic eclogites and blueschists, pelitic garnet phengite schists, marbles and serpentinites. The well‐preserved coesite inclusions were commonly found in eclogites, garnet phengite schists and marbles. Ti‐clinohumite and Ti‐chondrodite have been identified in UHP metamorphic serpentinites. Based on the PT pseudosection calculation and combined U‐Pb zircon dating, the P‐T‐t path has been outlined as four stages: cold subduction to UHP conditions before∼320 Ma whose peak ultrahigh pressure is about 30 kbar at 500 °C, heating decompression from the P max to the T max stage before 305 Ma whose peak temperature is about 600 °C at 22 kbar, then the early cold exhumation from amphibolite eclogite facies to epidote‐amphibolite facies metamorphism before 220 Ma and the last tectonic exhumation from epidote amphibolite facies to greenschist facies metamorphism. Combining with the syn‐subduction arc‐like 333‐326 Ma granitic rocks and 280‐260 Ma S‐type granites in the coeval low‐pressure and high‐temperature (LP‐HT) metamorphic belt, the tectonic evolution of Tianshan UHP metamorphic belt during late Cambrian to early Triassic has been proposed in this paper.
<p>Supplemental Texts S1–S2, Figures S1–S8, and Tables S1–S3, including the bulk-rock compositions of continental crust and lithospheric mantle used in the phase equilibrium modeling, the model setups and model results for the two-dimensional thermal-petrological models, and the model setups for the India-Asia collisional system.</p>
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