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348 results on '"Bao, Haifeng"'

74. Typical steppe ecosystems maintain high stability by decreasing the connections among recovery, resistance, and variability under high grazing pressure

Author

Zhang Xuefeng, Kang Saruul, Zhang Qing, Jianming Niu, Han Guodong, Zhao Mengli, Li Jiangwen, and Bao Haifeng

Subjects
Ecological stability, China, geography, Environmental Engineering, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Resistance (ecology), Ecology, Steppe, Biodiversity, 010501 environmental sciences, Grassland, 01 natural sciences, Pollution, Grazing pressure, Intermediate Disturbance Hypothesis, Environmental Chemistry, Environmental science, Ecosystem, Herbivory, Waste Management and Disposal, Restoration ecology, 0105 earth and related environmental sciences
Abstract

Grasslands in Inner Mongolia have been confronted with unprecedented degradation in recent years. Research on ecosystem stability is important to inform evaluation of the health of degraded grassland ecosystems. We examined synthetic stability, which was defined by the relationships between multiple components of stability, known as multidimensional stability, in grasslands at four stages of degradation (undegraded, slightly degraded, moderately degraded, and intensely degraded) in the Xilin River Basin, Inner Mongolia, China. We analyzed the connections between multidimensional stability and its relationship with four stability components, including community resistance and recovery measured on the basis of plant functional traits, and community functional (aboveground net primary productivity) and structural (Jaccard dissimilarity) variability, calculated on the basis of ten plots from different spatial distributions in a study site. Our results showed that (i) 9 of 17 traits displayed a significant trend along the grazing intensity gradient, indicating a clear turnover of species within communities in response to the grazing intensity gradient; (ii) moderately degraded (C) grasslands showed higher recovery, resistance, and synthetic stability than undegraded (A) and slightly degraded (B) grassland communities overall (recovery: p = 0.026, p = 0.032, for pairs of samples from A and C, and B and C, respectively; resistance: p = 0.024, for a pair of samples from A and C), which conformed with the intermediate disturbance hypothesis and positive diversity-stability relationship; and (iii) the multidimensionality of stability varied between different stages of degradation and were strongly dependent upon the correlations between stability components. Our study is expected to enrich the theory of stability maintenance in grassland ecosystems and provide guidance for grassland restoration and biodiversity conservation.

Published
2019

81. Desulfurization mechanism of thioether compounds in heavy oil on the (111) surface of inverse spinel Fe3O4.

Author

Li, Chen, Zhao, Mengmeng, Wang, Xing, Fang, Zheng, Chen, Yanling, and Bao, Haifeng

Abstract

The elimination of S-containing compounds in heavy oil is of significant importance to viscosity reduction and oil quality elevation in order to enhance oil recovery. In this study, the decomposition behavior of S-containing compounds in heavy oil was elucidated from a theoretical perspective in conjunction with simulative experiments. CH3SCH3 was employed as a model molecule on behalf of straight-chain saturated sulfides in heavy oil. The common cost-friendly inverse spinel Fe3O4 was selected as the catalyst. Our theoretical calculations revealed that the most feasible reaction pathway of entire CH3SCH3 decomposition occurred in two steps with the assistance of weakly adsorbed H2O molecules, generating two CH3OH molecules and one H2S molecule, of which the first step was the rate-determining step. These calculated results were confirmed with experimental results, which contributed to a clear and reliable catalytic desulfurization mechanism for S-containing compounds in heavy oil during aquathermolysis. [ABSTRACT FROM AUTHOR]

Published
2022
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