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Comparison of the Variation of Soil Respiration in Carbon Cycle in Temperate and Subtropical Forests and the Relationship with Climatic Variables

Shi Z., Zhang Y., Chen B., Zhou W., Du E., Fang J.

Polish Journal of Ecology

2015

Vol. 63, nr 3

365--376

Forest soil respiration (SR) has become a vital issue in global change ecology because of its critical role in global warming processes. However, SR remains the least understood component of the terrestrial carbon cycle because of its high spatial-temporal variability, inaccessibility of the soil substrate, and the high cost of measurement equipment. This study investigated the spatial and temporal variations of SR in six temperate and subtropical forest sites in eastern China. Seasonal variations of SR, the relationship between SR and soil temperature (ST) and volumetric water content (SW) were analyzed. Mean monthly SR varied seasonally and peaked in summer. SR varied temporally with ST (R2 = 0.43∼0.79) in different sites and varied spatially with latitude (R2 = 0.68). The responses of SR to the changes of SW varied across different sites and forest types. Their relationships were simulated by piecewise functions in the north three sites. The modules of ST and SW showed that ST is the dominant environmental factor in regulating seasonal dynamics of SR. This study is the first to examine the temporal and spatial variations of SR using a consistent method in situ in temperate and subtropical forests in eastern China. The results provide a scientific basis for accurately assessing future soil CO2 efflux as a result of climate changes, and aid predictions of the changes of forest SR.

Rheological Properties and Water-in-Oil Structural Stability of Emulsion Matrixes

Wang L., Fang J.

Central European Journal of Energetic Materials

2013

Vol. 10, no. 1

87--102

The emulsion explosive is one of the important industrial explosives.The structural stability of the water-in-oil (W/O) emulsion matrix of an emulsion ex plosive determines the reliability of its initiation, safety and detonation performance. It is known that the emulsifier is one of the most important factors affecting W/O structural stability. In this paper, several emulsifiers with the functionalities of imide, amide, ester, salt, and sorbin monooleate (SMO) were selected. From the perspective of the rheological properties, the effects of the emulsifier structure and its functionality on the viscosity and visco-elastic properties of the emulsion matrix were analyzed and researched. The results show that emulsifiers with imide/amide functionality and their corresponding emulsion matrixes have higher viscosity at normal temperatures and better fluidity at high temperatures than those of the others. The linear visco-elastic region (LVR) for emulsion matrixes containing these emulsifiers is wider than that of the others. The effect of a change in ambient temperature on the viscosity for a complex emulsifier is small. The emulsion matrix containing the emulsifier named LZ2727B is the most stable, followed by the emulsifier named LZ2727D. This conclusion is consistent with the conclusions from tension tests and from high and low temperature cycling experiments. From the emulsifiers studied in this paper, LZ2727B and LZ2727D emulsifiers are very suitable for manufacturing packaged emulsion explosives. On the other hand emulsifiers based on SMO functionalities, named LZ2731 and LZ2735, are the best choices for manufacturing bulk emulsion explosives.