Two new species of the genus <Emphasis Type="Italic">Cobitis</Emphasis> Linnaeus (Teleostei: Cobitidae) from southern China

Two new species of the genus Cobitis from southern China, C. hereromacula from the Luohe River in Guangdong Province and C. baishagensis from the Nandujiang River in Hainan Province, are described and illustrated here. C. hereromacula can be distinguished from its congeners by possessing the following combination of characteristics: absence of the second and third pigmentary zones of Gambetta; 13–16 oval blotches on the dorsum and 10–13 vertical, elongated triangular blotches below the midlateral line with more than 20 vertical dark brown bars between them; 6–7 narrow rows of dark spots on the caudal fin; a vertical oval spot smaller than the eye diameter on the upper part of the caudal peduncle; pointed mental lobes of the lower lip pointed with a slightly filiform tip; one slender and long needle-shaped lamina circularis at the base of the first branched ray of the male pectoral fins. C. baishagensis can be distinguished from its congeners by the fourth Gambetta zone being covered by 10–12 transverse elongated blotches; 4–5 narrow rows of dark spots on the caudal fin; a vertical blotch smaller than the eye diameter on the upper part of the caudal peduncle; males with a slender and long needle-shaped lamina circularis at the second branched pectoral fin ray in males; large scales with a slightly large focal zone; undeveloped mental lobes with a lower lip that does not end posteriorly in a filiform tip.     

鄂尔多斯盆地南部地区延长组深水沉积构造特征及地质意义

鄂尔多斯盆地南部地区上三叠统延长组长7段发育有典型的重力流沉积。对野外露头剖面进行大量调查研究,发现研究区重力流沉积发育丰富的沉积构造,底层面构造、软沉积变形构造是主要的两种类型。这种深水沉积构造组合能够很好地揭示研究区广泛发育的一定坡度背景下深水重力流沉积体系。滑移-滑塌沉积、砂质碎屑流沉积、浊流沉积是研究区发育最为广泛的深水重力流沉积类型,滑移-滑塌及软沉积变形构造为触发机制沉积响应,底层面构造为砂质碎屑流沉积及浊流沉积响应。综合分析研究区地层发育的大量凝灰岩夹层、深水泥岩中发育的植物碎屑、深水砂岩中发育的大量浅黄色泥砾等沉积特征,认为地震、火山喷发及季节性洪水为研究区深水重力流沉积最有利的触发因素。     

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.     

Preparation of integrative cubes as a novel biological permeable reactive barrier medium for the enhancement of in situ aerobic bioremediation of nitrobenzene-contaminated groundwater

Recent studies have indicated that in situ aerobic bioremediation is one of the most effective methods for remediating groundwater contaminated with nitrobenzene (NB). Aerobic bioremediation is largely dependent on the maintenance of adequate dissolved oxygen (DO) levels in the groundwater. Traditional in situ aeration has various disadvantages, such as high operational costs and nonuniform aeration. In this study, integrative cubes were prepared and utilized as a novel biological permeable reactive barrier (bio-PRB) medium to enhance the aerobic bioremediation of NB-contaminated groundwater. The results revealed an NB removal rate greater than 98.68% after 15–20 days of continuous oxygen release from the bio-PRB medium. DO concentrations reached 8.0 mg/L during treatment, and NB-degrading bacteria were able to tolerate a range of pH conditions. This multifaceted bio-PRB medium can simultaneously adsorb and biodegrade NB, release oxygen, and neutralize the pH with phosphate buffer. The results of this study suggest that this bio-PRB medium represents a highly effective in situ bioremediation method for NB-contaminated groundwater.     

Laboratory investigations of inert gas flow behaviors in compact sandstone

The seepage evolution behavior of compact rock is significant for the stability and safety of many engineering applications. In this research, both hydrostatic and triaxial compression tests were conducted on compact sandstone using an inert gas, namely argon. A triaxial compression test with a water permeability measurement was carried out to study the difference between the gas permeability and water permeability evolutions during the complete stress–strain process. Based on the experimental data, the hydrostatic stress-dependent gas permeability was discussed firstly. A second-order function was proposed to predict and explain the gas slippage effect. The mechanical properties and crack development of the sandstone samples were discussed to better understand the permeability evolution with crack growth during the complete stress–strain process. The results show that the gas permeability evolution can be divided into five stages according to the different crack growth stages. Then, the permeability changes in the crack closure stress \( \sigma_{\text{cc}} \), crack initiation stress \( \sigma_{\text{ci}} \), crack damage stress \( \sigma_{\text{cd}} \) and peak stress \( \sigma_{\text{p}} \) with confining pressures were analyzed. Finally, we found that the difference between the corrected gas permeability and water permeability can be attributed to the interaction between the water and sandstone grains.