Search

Schematic figure showing climate driving mechanisms on wetland hydrological and vegetational evolution. The relatively strong East Asian summer monsoon (EASM) with high precipitation tends to generate a higher water-level condition with more hygrophilous herbaceous plants while blocking the deposition of coarse grain-size fractions (a), and vise versa for weak EASM stages (b). [Display omitted] • The late-Holocene hydrological and vegetational regimes were reconstructed. • An ecological lake-to-wetland transition occurred at ~4.5 ka BP. • The wetlands evolution was largely controlled by monsoonal precipitation. The responding mechanism of wetland ecosystem to climate change is currently unclear due to a lack of long-term records incorporating multiple ecological factors. This paper presents a well-dated and multi-proxy cored record from a natural freshwater wetland developed in a paleo-pingo-related depression on the Sanjiang Plain. The study aims to reconstruct the wetland water-level and vegetational regimes during the past ~6.0 ka BP and discuss the wetland evolution response to the East Asian summer monsoon (EASM) circulation. The results show that a shallow-water lake with hygrophilous herbs developed in the depression with a strong EASM during ~6.0–4.5 ka BP. The paleolake was succeeded by a wetland with a lowered mean water level and an increase in tree cover controlled by the weakened EASM during the past 4.5 ka BP. Such an ecological lake-to-wetland transition corresponds well to the sharp decline of the EASM around 4.5 ka BP which has been well documented in various geological records across the EASM domain. During the wetland developing stage over the past 4.5 ka BP, the water-level and vegetational changes in the studied depression were also closely related to the EASM variations. The strengthened EASM usually generated higher water levels with more hygrophilous herbs around 4.0 ka BP, 3.5 ka BP, 3.0 ka BP, 2.0 ka BP, and 1.3 ka BP. Considering the prevalent EASM climate serving as the predominant water supply for the wetlands on the modern Sanjiang Plain, we suggest the EASM circulation has played a critical role in driving the wetland ecological evolution during the mid-to-late Holocene Epoch. The past 0.4 ka BP is an exception as the local Trees/Herbs ratio visibly increased with the declined water level, while the monsoonal precipitation shows no equivalent shift. The wetland evolution at this stage was attributed to human interference. [ABSTRACT FROM AUTHOR]

A new derivation of the three-dimensional (3D) limit equilibrium method for slope stability analyses is presented, which applies linear algebra operations to matrices to achieve a highly efficient algorithm while maintaining the rigorousness of the formulation. It satisfies six equilibrium conditions and includes all of the components of the intercolumnar forces. The generalized 3D Morgenstern-Price's (MP) assumption for the intercolumn forces is recast into incremental forms. The advantage is that the unknowns of the different physical meanings (i.e., factor of safety (FS) and the coefficients in the MP assumption) are determined by balancing the forces and moments independently. Along with the recasting correction coefficients, they are solved with the triple nested algorithm. The numerical instability that is related to the different orders of magnitude for the residuals is avoided. The varication examples show: (i) the insensitivity of the FS to the prescribed functions in the MP assumption, (ii) the reliability of the method to cope with a complicated slope geometry (simplified methods may provide a larger FS for certain cases), and (iii) the superior efficiency of the algorithm (requires several seconds to converge). This study proposes a practical way to track the irregular 3D tension cracking by repeating the analysis and excluding the columns with the negative normal forces at the bottom. This formulation is applied to a valley landfill slope in China. In comparison to the two-dimensional analysis, there are more reasonable/cost-effective measures to increase the system stability through 3D analyses for several conditions (e.g., seismic loading). • A new three-dimensional method is devised by concise linear algebra operations. • It considers 6 equilibrium conditions and all intercolumnar force components. • Triple nested algorithm achieves a high-efficiency and a good convergence. • Factor of safety is insensitive to the intercolumn force distribution function. • A practical way is proposed to track highly irregular tension cracking surface. [ABSTRACT FROM AUTHOR]

The environmental impacts of grid-connected photovoltaic (PV) power generation from crystalline silicon (c-Si) solar modules in China have been investigated using life cycle assessment (LCA). The life cycle inventory was first analyzed. Then the energy consumption and greenhouse gas (GHG) emission during every process were estimated in detail, and finally the life-cycle value was calculated. The results showed that the energy payback time ( T EPBT ) of grid-connected PV power with crystalline silicon solar modules ranges from 1.6 to 2.3 years, while the GHG emissions now range from 60.1 to 87.3 g-CO 2 ,eq/kW h depending on the installation methods. About 84% or even more of the total energy consumption and total GHG emission occupied during the PV manufacturing process. The solar grade silicon (SoG-Si) production is the most energy-consuming and GHG-emitting process, which accounts for more than 35% of the total energy consumption and the total GHG emission. The results presented in this study are expected to provide useful information to enact reasonable policies, development targets, as well as subsidies for PV technology in China. [ABSTRACT FROM AUTHOR]

Highlights: [•] China’s PV industry’s development history and status quo were introduced. [•] The existing problems and challenges were analyzed based on field studies. [•] Policy recommendations and possible implementation incentives were provided. [ABSTRACT FROM AUTHOR]

Abstract: A new concept of ‘low-carbon towns’ (LCTs) has emerged in the urban planning and development of China in recent years to face the challenge of global climate change. This manuscript presents the current status, basic concepts, and town practices for the development of LCTs in China. First, we summarize the driving forces and regional activities for the development of LCTs in China; then, we introduce the town types and related programs. We propose the definition of a Chinese LCT and the main approaches to developing Chinese LCTs through a system analysis revealing what they are and how they may be developed in a Chinese context. The proposed approaches to develop Chinese LCTs include economic, social, layout, technology, and reuse approaches, each of which is introduced in the context of typical town planning and management in China. [Copyright &y& Elsevier]

• Clay minerals promote LTO with larger O 2 consumption and COx release. • The yield of coke increased and that of produced oil decreased by montmorillonite. • The composition and properties of coke are obviously changed by clay minerals. • The compositions of produced oil and hydrocarbons remain nearly unchanged. • The mechanism how the clay minerals affect the LTO of heavy oil is analyzed. In situ combustion (ISC) is an efficient method to recover heavy oil, in which low-temperature oxidation (LTO) is an important process. A fixed-bed reactor was used to conduct ramped temperature oxidation experiments on a mixture of heavy oil from China, silica and clay minerals, including montmorillonite, kaolinite, illite and chlorite. The four clay minerals promoted the LTO of heavy oil, which was reflected in the increase in the total amount of O 2 consumption with the decrease in the peak temperature and the change in the composition and yield of gas, liquid and solid products. The total amounts of CO and CO 2 release increased, and the peak temperature decreased. The total amount of hydrocarbons in the gas phase decreased, whereas the peak temperature and main components didn't change. The presence of clay minerals showed little effect on the composition of produced oil, whereas the presence of montmorillonite decreased the yield of produced oil. The yield and O/C ratio of coke increased, the heat value of coke decreased and the oxidation activity of coke improved in the presence of clay minerals. Montmorillonite showed the most notable effect. The mechanism of the effects of clay minerals on the LTO of heavy oil was analyzed by combining the change in the distribution proportion of O and C in products. Montmorillonite had large specific surface area and adsorption capacity and catalyzed decarbonylation, decarboxylation and polycondensation. The other three clay minerals mainly affected the LTO of heavy oil through the catalysis of decarbonylation, decarboxylation and polycondensation. [ABSTRACT FROM AUTHOR]