Occurrence and conceptual sedimentary model of Cambrian gypsum-bearing evaporites in the Sichuan Basin,SW China

During the Cambrian, gypsum-bearing evaporites formed in the Sichuan Basin, SW China. These rocks are important for oil and gas sealing, but details of their distribution and origin are not well established. This study examines the regional distribution and origin of the gypsum-bearing evaporites using a comprehensive analysis of drilling data from 34 wells, 5 measured cross-sections in the basin and surrounding area, and 96 maps of area-survey data. Results show that in the stratigraphic succession, the gypsum-bearing evaporites occur mainly in the Lower Cambrian Longwangmiao Formation, the Middle Cambrian Douposi Formation, and the Middle-Upper Cambrian Xixiangchi Group. Geographically, the rocks are found mainly in the southeastern part of the basin, and the distribution of deposits shows an overall SW-NE trend. The sedimentary environments for evaporite formation were evaporative lagoon and inter-platform basin in a platform setting. Gypsum was generated by the underwater concentration of sea water in a strongly evaporative environment. Both an evaporative restricted platform and a mixeddeposition restricted platform model appear to be applicable to the development of gypsum in the Sichuan Basin. The gypsum-bearing evaporites with the best sealing capacity are located mostly in the southeastern part of the basin. These constraints can be applied directly to regional exploration, and have implications for the regional paleogeography and paleoclimate.     

Experimental Study of the SiO<Subscript>2</Subscript>–H<Subscript>2</Subscript>O–KF–KCl–NaF System at 700–800°C and 1–2 kbar Based on Synthetic Fluid Inclusions in Quartz

The phase state of the fluid in the H₂O–KF ± KCl ± NaF system is studied in the presence of quartz for an experimental assay of the mutual influence of various salts of the fluid-forming mixture on heterogeneous fluid equilibria. The fluid inclusions were synthesized in quartz by the fracture healing method from solutions with KF + KCl and KF + NaF mixtures at 1 or 2 kbar and 700, 750, or 800°C. The results of the fluid inclusion study indicate a heterogeneous state of the fluid and variation in the fluid composition during experiments as a result of its interaction with quartz. The increase in temperature and pressure, as well as variation in the proportions of the salt contents in the fluid-forming mixture, changed the course of chemical reactions. After all the experiments, a glassy phase was observed in some types of inclusions. It is known that aqueous KF or KCl solutions, the solubility of which increases during heating, are characterized by phase equilibria of systems of the first type (Valyashko, 1990), when liquid and vapor are equilibrated for a heterogeneous state of the fluid. In this case, some inclusions should homogenize to vapor. However, no similar inclusions were observed in contrast to denser fluid phases (liquids), which are typical of the upper heterogeneous area of systems of the second (P–Q) type. Some inclusions host solid phases, the solubility of which decreases as the temperature increases. The results of experiments in the presence of KF + NaF solutions showed that the amount of inclusions of heterogeneous entrapment increases at higher temperatures simultaneously with a decrease in the H₂O content of the glassy phase.     

The oldest (~ 1.9 Ga) metadolerites of the southern Siberian craton: age,petrogenesis, and tectonic setting

Geological, geochronological, and isotope-geochemical studies of the metadolerites of the Angaul complex, widespread in the Urik-Iya graben of the southern Siberian craton, were carried out. The metadolerites forming separate conformal bodies (sills) among the metasandstones of the Ingash Formation were studied in detail. U-Pb zircon (SHRIMP) dating of metadolerites yielded an age of 1913 ± 24 Ma, and U-Pb baddeleyite (ID-TIMS) dating of these rocks yielded an age of 1914.0 ± 1.7 Ma. Thus, the date of 1914 ± 2 Ma can be taken as the most precise age estimate for the studied rocks. The metadolerites of the Angaul complex correspond in chemical composition to the normal-alkaline tholeiitic basalts. Metadolerites are differentiated rocks with mg# of 36 to 58. They show fractionated REE patterns: (La/Yb)_n = 1.2-3.5. All metadolerites, independently of their mg# value, have low contents of Nb (1.6-10.2 ppm) and show well-pronounced negative Nb-Ta anomalies in multielement patterns (Nb/Nb* = 0.19-0.54). The metadolerites are characterized by positive ε_Nd(T) values ranging from 0.4 to 5.2, which correlate well with their SiO₂ content and mg# value. The isotope-geochemical parameters of the metadolerites of the Angaul complex indicate that fractional crystallization, along with the assimilation of the host rocks (AFC), might have been the main process during the formation of the most differentiated metadolerites. The geochemical characteristics of metadolerites with the maximum mg# values of 57-58 and ε_Nd(T) = 5.2 suggest that the parental mantle source of the metadolerites resulted from mixing of predominant depleted mantle material with the subcontinental-lithosphere material. Intrusion of the dolerites of the Angaul complex, as well as the deposition of the sedimentary strata of the Ingash Group, took place at the Paleoproterozoic stage of intracontinental extension caused by the collapse of the orogen resulted from the collision of the Biryusa block with the Tunguska superterrane in the southern Siberian craton.     

A robust mesh optimisation method for multiphase porous media flows

Flows of multiple fluid phases are common in many subsurface reservoirs. Numerical simulation of these flows can be challenging and computationally expensive. Dynamic adaptive mesh optimisation and related approaches, such as adaptive grid refinement can increase solution accuracy at reduced computational cost. However, in models or parts of the model domain, where the local Courant number is large, the solution may propagate beyond the region in which the mesh is refined, resulting in reduced solution accuracy, which can never be recovered. A methodology is presented here to modify the mesh within the non-linear solver. The method allows efficient application of dynamic mesh adaptivity techniques even with high Courant numbers. These high Courant numbers may not be desired but a consequence of the heterogeneity of the domain. Therefore, the method presented can be considered as a more robust and accurate version of the standard dynamic mesh adaptivity techniques.     

Landslides triggered by the 2016 Mj 7.3 Kumamoto,Japan, earthquake

The aim of this study is to establish a detailed and complete inventory of the landslides triggered by the Mj 7.3 (Mw 7.0) Kumamoto, Japan, earthquake sequence of 15 April 2016 (16 April in JST). Based on high-resolution (0.5–2 m) optical satellite images, we delineated 3,467 individual landslides triggered by the earthquake, occupying an area of about 6.9 km². Then they were validated by aerial photographs with very high-resolution (better than 0.5 m) and oblique field photos. Of them, 3,460 landslides are distributed in an elliptical area about 6000 km², with a NE-SW directed 120-km-long long axis and a 60-km-long NW-SE trending short axis. Most of the landslides are shallow, disrupted falls and slides, with a few flow-type slides and rock and soil avalanches. The analysis of correlation between the landslides and several control factors shows the areas of elevation 1000–1200 m, stratum of Q₃-Hvf, seismic intensity VIII and VIII+, and peak ground acceleration (PGA) 0.4–0.6 g register the highest landslide abundance. This study also discussed the relationship between the spatial pattern of the landslides and the seismotectonic structure featured by a strike-slip fault with a normal component and the volcanism in the study area.     

Health risk of heavy metals from vegetables irrigated with sewage water in peri-urban of Dera Ismail Khan,Pakistan

Health risks of heavy metals in vegetables irrigated with sewage water were investigated in the present study. The findings indicated a massive accumulation of heavy metals in soil and vegetables collected from Dera Ismail khan, Pakistan. The concentration levels of heavy metal in vegetables grown on soil irrigated with untreated sewage water were significantly higher at (P ≤ 0.001) than in vegetables grown on fresh-water-irrigated soil and proceeded the recommended limits of World health organization. Moreover, the findings also indicated that the adults and children consuming such vegetables ingested a large proportion of the selected toxic metals. Health risk index was greater than one for Pb and Cd in all the selected vegetables and was greater than one for Ni in three vegetables like Spinacia oleracea, Benincasa fistulosa and Lactuca sativa. Health risk assessment would be a useful tool for information regarding any threats of heavy metals contamination in vegetables.     

Photodegradation of dimethyl phthalate (DMP) by UV–TiO<Subscript>2</Subscript> in aqueous solution: operational parameters and kinetic analysis

In this paper, the adsorption and degradation phenomenon involved in the photocatalytic degradation of dimethyl phthalates (DMPs) by titanium dioxide (TiO₂) was studied. A variety of operating variables were selected firstly. Then, it was proved that even for such weak adsorption properties molecules as DMP, adsorption was still an important prerequisite for photolysis. A surface-mediated reaction process was proposed that the photodegradation of DMP assisted by TiO₂ particles occurred primarily at the surface of the photocatalyst rather than in the homogeneous phase. According to Langmuir–Hinshelwood model, the adsorption constant determined from the dark adsorption was far less than that obtained in the light condition. Enhanced DMP adsorption on the surface of TiO₂ under irradiation was the possible reason for the improvement of photodegradation efficiency. Under the irradiation of light, a synergistic mechanism of adsorption and photocatalysis was responsible for DMP degradation. The quantitative analysis by adding scavengers indicated that ^·OH radical was primarily responsible for the photodegradation of DMP. It was further verified that ^·OH was produced much more from conduction band electrons rather than valance band holes toward photodegradation of DMP by adding foreign Cu²⁺.     

Preservation of thermophilic mixed culture for anaerobic palm oil mill effluent treatment by convective drying methods

The generation of huge amount of liquid waste known as palm oil mill effluent is a major problem in oil palm industry. Meanwhile, anaerobic biodegradation of such organic effluent at thermophilic condition is a promising treatment technology due to its high efficiency. However, storage and transportation of thermophilic mixed culture sludge are challenging due to constant biogas generation and heating requirement. Hence, drying of thermophilic sludge was conducted to obtain dormant thermophiles and thus enables easier handling. In this study, thermophilic sludge was dried using heat pump at 22 and 32 °C as well as hot air oven at 40, 50, 60, and 70 °C. Subsequently, quality of dried sludge was examined based on most probable number enumeration, chemical oxygen demand, and methane yield. Average drying rate was found to increase from 3.21 to 17.84 g H₂O/m² min as drying temperatures increases while average moisture diffusivity values ranges from 5.07 × 10^?9 to 4.34 × 10^?8 m²/s. Oven drying of thermophilic mixed culture resulted in highest chemical oxygen demand removal and lowest log reduction of anaerobes at 53.41% and 2.16, respectively, while heat pump drying resulted in the highest methane yield and lowest log reduction of methanogens at 53.4 ml CH₄/g COD and 2.09, respectively. To conclude, heat pump at 22 °C was most suitable drying technique for thermophilic mixed culture as the original methane-producing capability was largely retained after drying, at a slightly lower yet still comparable chemical oxygen demand removal when palm oil mill effluent was treated with the rehydrated culture.     

Application of magnetic adsorbent with silicate and phenyl polymers to adsorb Rhodamine B

The extensive use of Rhodamine B (RhB) for textile, paper, pigment, food, cosmetic, and drug manufacturing and its indiscriminate disposal leads to serious human, biological, and environmental hazards. A magnetic adsorbent with silicate and phenyl polymers (Ph/SiO₂/Fe₃O₄) has been prepared to absorb RhB. The morphology and structure of the adsorbents have been characterized by TGA, XRD, FTIR, and adsorption–desorption measurement. The results revealed that Ph/SiO₂/Fe₃O₄ exhibited a paramagnetic behavior and could easily and quickly be separated from a suspension. The RhB adsorption behavior was almost pH independent due to the adsorption between the phenyl ring of Ph/SiO₂/Fe₃O₄ and RhB by π–π electron-donor–acceptor interactions. The adsorption behavior of RhB adsorption was in good agreement with the Langmuir adsorption isotherm, and the maximum adsorption capacity was 142.186 mg g^?1. Good desorption performance of Ph/SiO₂/Fe₃O₄ showed that this novel magnetic adsorbent cannot only be activated by ethanol extraction process but also reuse by the recovery of magnetic force.     

Soil column infiltration tests on biomediated capillary barrier systems for mitigating rainfall-induced landslides

Rainfall-induced landslide is a common geohazard in tropical and humid regions. Capillary barrier system (CBS) is a popular and widely studied mitigating measure for rainfall-induced landslides. However, several previous studies have shown that the performance of the conventional CBS under intense rainfalls has not been particularly convincing. This paper aims to explore the feasibility and effectiveness of a newly proposed system, known as “biomediated capillary barrier system” (B-CBS) in minimizing water infiltration into soil. A one-dimensional soil column was used to investigate the infiltration characteristics of the proposed system. The results showed that the B-CBS of biomediated residual soil overlying original residual soil (Test IV) could effectively control the infiltration into soil by taking advantage of the less-permeable biomediated soil cover. The B-CBS of biomediated residual soil overlying gravelly sand (Test V) and the three-layered B-CBS of fine sand overlying gravelly sand and biomediated residual soil (Test VI) showed the best performance in terms of minimizing the water infiltration. A suction of about 5 kPa still remained in the soil column after 60 min of infiltration from the ponded water on the soil surface.