Search

Currently, China is at a critical stage of economic transformation and pollution control. The environmental pollution control efficiency (PCE) deserves more in-depth study. This paper adopts a three-stage global data envelopment analysis (DEA) model and a global Malmquist index model to measure the PCE and the sources of its changes in China from 1991 to 2019. Study shows that: (1) the overall level of PCE has remained low over the past 29 years, and it has a slowly fluctuating upward trend, with an average annual growth rate of only 0.92 %; (2) the lower pure technical efficiency hinders the effectiveness of environmental pollution control, which is mainly affected by the slow technological progress; and (3) at the provincial level, the overall efficiency of Shanghai and Guangxi has long been above 0.9, while the efficiency of other provinces has been below 0.9 for quite a long time. At the regional level, the Yangtze River Delta is the most effective area, while the Yellow River Basin is the most ineffective area. In consideration of this, we provide specific strategies for improving PCE of each province, from three aspects of increasing the capital input, optimizing the scale structure, and upgrading technology level. [Display omitted] [ABSTRACT FROM AUTHOR]

• Mechanism of high frequency harmonic resonance of Luxi VSC-HVDC project is analyzed. • Time delay and system impedance will influence the high frequency harmonic resonance. • A method to suppress the high frequency harmonic resonance is proposed. This paper introduces the basic situation of high frequency harmonic resonance in Guangxi on April 10, 2017, which is based on the Luxi back-to-back voltage source converter based high voltage direct current transmission (VSC-HVDC) project in China. Firstly, the harmonic amplification mechanism and its key links in the event are analyzed in detail and verified by simulation. Secondly, the relationship among high frequency harmonic resonance, voltage feedforward control loop and system harmonic impedance is obtained, and the formulas among voltage feedforward control parameters, system harmonic impedance and high frequency harmonic resonance frequency amplitude are deduced. Then, a method to suppress high frequency harmonic resonance by adding a reasonably filter to the voltage feedforward control loop is proposed. Finally, the effectiveness of the proposed method in this paper is verified by simulation and field operation. [ABSTRACT FROM AUTHOR]

Mineral resource extraction is often accompanied by severe environmental pollution and ecological damage, hindering mining economies from achieving sustainable development. This paper aims to promote the goal of cleaner production in extractive industries from the perspective of environmental management through a more accurate understanding of how human activities affect the extractive industries. This requires more granular data for environmental damage in mining. The article proposes an ecological threat assessment framework for mining to support sustainable processes in the extractive industry. It integrates biophysical variables, technical indicators, and human activity data. The study is based on data at the mine level with 17 indicators used to evaluate the ecological impact of 13960 mines in Guangxi, China, from 2008-to 2018 in four dimensions: economic and technical indicators of mines themselves, surrounding economic activity, geological and environmental vulnerability, and ecological status of mining sites. Data from multiple sources were used to assess, map, and monitor ecological impacts in mining areas, such as high-resolution satellite images, interview data, environmental assessment reports, and mining rights data. We evaluated the ecological impact level of each mine and the extent to which spatial heterogeneity of regional economic and environmental preferences affected the degree of ecological impact. The results show that growth in population income has changed environmental preferences and driven down environmental disturbances in mines. Reduced dependence of regional economies on the industrial sector has also contributed to environmental improvements. In addition, increasing environmental regulation has limited the ecological impacts of mining, but these environmental regulation impacts are regionally heterogeneous. The effect of laws and rules is lower in cities and regions dependent on mineral resources, where resource extraction companies have more bargaining power. The results of this study will inform environmental management in the mining sector and support sustainable development in the region. [Display omitted] [ABSTRACT FROM AUTHOR]

The defected kaolinite is common in sedimentary kaolin, but its structure and disorder mechanism remains unclear. In this paper, three different size distributions of kaolinite particles: 0–300 nm, 200–1000 nm, and 500–2000 nm, were separated and classified from high-defect sedimentary kaolin, collected from Quaternary sedimentary kaolin in Guangxi Zhuang Autonomous Region of China. The three particle sizes of kaolinite have been monitored by particle size analyzer, high-resolution magic-angle spinning NMR (MAS NMR), small and wide-angle X-ray scattering (SAXS and WAXS), X-ray diffraction (XRD), BET surface analyzer, nitrogen gas-adsorption, scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). The results revealed that the smallest particle size of kaolinite exhibited high degrees of broken Al-O-Al and Si-O-Si bonds, more disordered structure, and elevated specific surface area. The degree of the structural disorder of kaolinite increases as the particle size decreases, which can be attributed to the more aluminum substituted for silicon in tetrahedron sheet in the finer kaolinite crystal, compared to the coarser kaolinite crystals. • Kaolinite particles were separated into three parts, <300 nm, 200–1000 nm, and 500–2000 nm. • The degree of the disorder increases as the kaolinite particle size decreases. • The smallest particle size of kaolinite showed high degrees of broken Al-O-Al and Si-O-Si bonds. [ABSTRACT FROM AUTHOR]

[Display omitted] • Trace elements in sphalerite and pyrite distributed in the form of solid solutions or micro-inclusions. • The mineralization in the Beishan Pb-Zn ore district was under a low-temperature condition. • The Pb-Zn deposits in the Beishan Pb-Zn ore district are MVT deposits. The Beishan Pb-Zn ore district, located in northern Guangxi, China, is a giant carbonate-hosted Pb-Zn ore district. In-situ trace element analysis was performed using LA-ICP-MS on sphalerite and pyrite from three representative Pb-Zn deposits in the Beishan Pb-Zn ore district. The analysis of these trace elements reveals the trace element compositions of the sulfides, the distributions and the substitution mechanisms of trace elements, physicochemical characteristics of the ore-forming fluids, and ore genesis. Sphalerite is enriched in Mn, Fe, Ge, and Cd, while it is poor in Co, Ni, Ga, As, In. Pyrite is enriched in Co, Ni, As, Tl, Sb, and Pb, but poor in Mn, Ga, Ge, Cd, In, Sn. Mn, Fe, Cd, Ga, Ge, Sb, Ag, and As in sphalerite enter the mineral lattice mainly by simple or coupled substitution mechanisms, while Cu and Pb can enter the mineral lattice in the form of solid solution or micro-inclusions. Mn, Co, Ni, As, Tl, and Sb in pyrite substituted Fe2+ by simple or coupled mechanisms, while Pb can enter the mineral lattice in the form of solid solution or micro-inclusions. Studies of trace elements related to temperature (e.g., Mn, Fe, Ga, Ge, In) in sphalerite and pyrite indicated that mineralization in the Beishan Pb-Zn ore district occurred under a low-temperature condition. And according to the sphalerite GGIMFis geothermometer, the mineralization temperature of the Beishan Pb-Zn ore district was 55–268 °C (average 153 °C), of which 110–230 °C(average 153 °C) in Duchuan, 92–268 °C (average 149 °C) in Beishan, and 55–243 °C (average 167 °C) in Dongyong. The Mn, Fe, Ga, Ge, and In contents of sphalerite are similar to those of MVT deposits. The combination of some binary pattern diagrams, principal component analysis (PCA), and Co/Ni ratios of pyrite, with the geological features and physicochemical properties of the ore-forming fluids, indicates that the Beishan Pb-Zn ore district is an MVT district. This paper, combined with previous studies, shows that the Co/Ni ratio of pyrite has some guiding significance for mineral exploration of this kind of Pb-Zn deposit, with Co/Ni values around 0.1 indicating that the deposit has a better prospect of developing into a large deposit, and Co/Ni much less than 0.1 indicating that the deposit may not have a good prospect. [ABSTRACT FROM AUTHOR]

This paper reports the discovery of a new mammalian assemblage at Mocun cave in 2000 by the Natural History Museum of Guangxi. The Mocun site is located in a residual karst peak in southwest Guangxi, south China. Abundant mammalian fossil teeth and bones were extracted from relatively thick deposits, well constrained stratigraphically. The results show that 1) the Mocun fauna is composed of typical species of the " Ailuropoda - Stegodon association", including Stegodon, Ailuropoda, Rhinoceros, Pongo, Tapiru s, Megatapirus, and Elephas, common in the Middle to the Late Pleistocene, with a larger portion of modern species; 2) By employing U-series dating (MC-ICP-MS) method on both the soda straw stalactites and mammalian teeth collected from deposits, the age of the Mocun fauna has been constrained between 66 and 101 ka, a transitional period from the interglacial stage MIS5 to the beginning of the last glacial stage (MIS4), representing one of the securely dated Late Pleistocene sites in southern China so far; 3) The composition in large mammals suggests a forested environment which harboured a great biodiversity in large species; 4) The taphonomic analysis indicates that the fossil accumulation is mainly due to activities of porcupines and to water flows; 5) Interestingly, our taxonomic study reveals some changes in the occurrence of Tapirus sinensis and Megatapirus augustus between ∼66 and ∼86 Ka, along with a change in the abundance of artiodactyls versus primates. It remains to demonstrate with more comprehensive records if these changes may be related to the mid-Late Pleistocene climatic transition. • a new mammalian fauna cave site (Mocun cave) with accurate date to 66 and 101 ka in southwest Guangxi. • The composition in large mammals suggests a compatible habitat for a great biodiversity of species. • Some changes between layers with Tapirus sinensis replaced by Megatapirus augustus between ∼66 and ∼86 Ka, along with a change in the abundance of artiodactyls versus primates. [ABSTRACT FROM AUTHOR]

Within the cultural context of "guanxi" in China, it is particularly challenging to develop a framework capable to capture the complexity and adaptability of farmers facing conflicts between wetland conservation and livelihood development. In this paper, we integrate agent-based model (ABM) and field experimental methods to develop a hybrid simulation experiment model for wetland conservation behavior, in order to reveal the driving forces of land change and understand the dynamic change process of farmers' behavior. Through a field experiment and a questionnaire survey of farmers around the Shankou Mangrove Ecological Nature Reserve (SMENR) in Guangxi, China, the intention of different types of farmers to adopt wetland conservation behavior was assessed from different angles, constructing a rational choice theory (RCT) framework and ABM proxy behavior rules. The results showed that after 5 years, the adoption rate of farmers' wetland conservation behavior reached 100% under the assumption of bounded self-interest, but only about 80% under bounded rationality. This confirms that herd is more conducive to promoting farmers' wetland conservation behavior. Decision makers should consider the importance of bounded rationality and bounded self-interest interaction, foster farmers' sense of belonging and responsibility toward wetlands, and guide farmers to participate in the ecological protection and sustainable use of wetlands. [Display omitted] • Herd is more conducive to promoting farmers to protect wetlands. • The fastest take-off can be achieved at a threshold of about 20%. • Livelihood patterns lead to differences in willingness to protect wetlands. • Sense of belonging and responsibility is important for wetland conservation. • Combining experimental economics and ABM can improve the accuracy of the model. [ABSTRACT FROM AUTHOR]