In order to improve the fine structure inversion ability of igneous rocks for the exploration of underlying strata, based on particle swarm optimization(PSO), we have developed a method for seismic wave impedance inve...In order to improve the fine structure inversion ability of igneous rocks for the exploration of underlying strata, based on particle swarm optimization(PSO), we have developed a method for seismic wave impedance inversion. Through numerical simulation, we tested the effects of different algorithm parameters and different model parameterization methods on PSO wave impedance inversion, and analyzed the characteristics of PSO method. Under the conclusions drawn from numerical simulation, we propose the scheme of combining a cross-moving strategy based on a divided block model and high-frequency filtering technology for PSO inversion. By analyzing the inversion results of a wedge model of a pitchout coal seam and a coal coking model with igneous rock intrusion, we discuss the vertical and horizontal resolution, stability and reliability of PSO inversion. Based on the actual seismic and logging data from an igneous area, by taking a seismic profile through wells as an example, we discuss the characteristics of three inversion methods, including model-based wave impedance inversion, multi-attribute seismic inversion based on probabilistic neural network(PNN) and wave impedance inversion based on PSO.And we draw the conclusion that the inversion based on PSO method has a better result for this igneous area.展开更多
Native plant communities are commonly invaded by invasive plants to different degrees.However,the relative contribution of the invasive plant abundance vs.phylogenetic evenness to the responses of wetland communities ...Native plant communities are commonly invaded by invasive plants to different degrees.However,the relative contribution of the invasive plant abundance vs.phylogenetic evenness to the responses of wetland communities to different degrees of invasion is still unclear.In addition,whether such contribution varies with environmental conditions such as flooding is also unclear.To address these questions,we chose Alternanthera philoxeroides as the invasive plant,and set up four invasive degrees by changing the community species composition under both flooding and non-flooding conditions.The relative abundance of A.philoxeroides and phylogenetic evenness changed simultaneously with the change in the community invasion degree.The invasion degree significantly affected the individual biomass of A.philoxeroides and some native species.Variation partitioning showed that the relative abundance of A.philoxeroides contributed more to variation in community indicators than phylogenetic evenness,regardless of flooding.Spearman rank correlation test showed that the relative abundance of A.philoxeroides was negatively correlated with the individual biomass of A.philoxeroides and some native species,while the phylogenetic evenness was positively correlated with only a few native species.And their correlation strength and significance were all affected by specific species and flooded environment.In conclusion,our results suggest that the relative abundance of A.philoxeroides can more effectively explain the wetland community response to different invasion degrees than phylogenetic evenness,regardless of flooding.展开更多
Tailings of a Pb and Zn mine as a metal-contaminated area （Zone 1） with two pioneer plant species, Peganum harmala and Zygophyllum fabago, were investigated and compared with a non-contaminated area （Zone 2） in th...Tailings of a Pb and Zn mine as a metal-contaminated area （Zone 1） with two pioneer plant species, Peganum harmala and Zygophyllum fabago, were investigated and compared with a non-contaminated area （Zone 2） in the vicinity. Total concentrations of Pb, Zn, and Cu in the soil of Zone 1 were 1 416, 2 217, and 426 mg kg-1, respectively, and all exceeded their ranges in the normal soils. The soil pH was in the neutral range and most of the physical and chemical characteristics of the soils from both zones were almost similar. The species Z. fabago accumulated higher Cu and Zn in its aerial part and roots than the normal plants. On the other hand, their concentrations did not reach the criteria that the species could be considered as a metal hyperaccumulator. The species P. harmala did not absorb metals in its roots; accordingly, the accumulation factor values of these metals were lower than 1. The contents of chlorophyll, biomass, malondialdehyde, and dityrosine in these two species did not vary significantly between the two zones studied. In Zone 1, leaf vacuoles of Z. fabago stored 35.6% and 43.2% of the total leaf Cu and Zn, respectively. However, in this species, the levels of phytochelatins （PCs） and glutathione （GSH） and antioxidant enzyme activities were significantly higher in Zone 1 than in Zone 2. In conclusion, metal exclusion in P. harmala and metal accumulation in Z. fabago were the basic strategies in the two studied pioneer species growing on the metal-contaminated zone. In response to metal stress, elevation in antioxidant enzyme activities, increases in the PCs and GSH levels in the aerial parts, and metal storage within vacuoles counteracted each other in the invasion mechanism of Z. ]abago.展开更多
基金provided by the National Science and Technology Major Project(No.2011ZX05004-004)China National Petroleum Corporation Key Projects(No.2014E2105)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘In order to improve the fine structure inversion ability of igneous rocks for the exploration of underlying strata, based on particle swarm optimization(PSO), we have developed a method for seismic wave impedance inversion. Through numerical simulation, we tested the effects of different algorithm parameters and different model parameterization methods on PSO wave impedance inversion, and analyzed the characteristics of PSO method. Under the conclusions drawn from numerical simulation, we propose the scheme of combining a cross-moving strategy based on a divided block model and high-frequency filtering technology for PSO inversion. By analyzing the inversion results of a wedge model of a pitchout coal seam and a coal coking model with igneous rock intrusion, we discuss the vertical and horizontal resolution, stability and reliability of PSO inversion. Based on the actual seismic and logging data from an igneous area, by taking a seismic profile through wells as an example, we discuss the characteristics of three inversion methods, including model-based wave impedance inversion, multi-attribute seismic inversion based on probabilistic neural network(PNN) and wave impedance inversion based on PSO.And we draw the conclusion that the inversion based on PSO method has a better result for this igneous area.
基金supported by the Fundamental Research Funds for the Central Universities(2015ZCQ-BH-01)the National Key Research and Development Program(2016YFC1201100)the China Major Science and Technology Program for Water Pollution Control and Treatment(2017ZX07602-004-003).
文摘Native plant communities are commonly invaded by invasive plants to different degrees.However,the relative contribution of the invasive plant abundance vs.phylogenetic evenness to the responses of wetland communities to different degrees of invasion is still unclear.In addition,whether such contribution varies with environmental conditions such as flooding is also unclear.To address these questions,we chose Alternanthera philoxeroides as the invasive plant,and set up four invasive degrees by changing the community species composition under both flooding and non-flooding conditions.The relative abundance of A.philoxeroides and phylogenetic evenness changed simultaneously with the change in the community invasion degree.The invasion degree significantly affected the individual biomass of A.philoxeroides and some native species.Variation partitioning showed that the relative abundance of A.philoxeroides contributed more to variation in community indicators than phylogenetic evenness,regardless of flooding.Spearman rank correlation test showed that the relative abundance of A.philoxeroides was negatively correlated with the individual biomass of A.philoxeroides and some native species,while the phylogenetic evenness was positively correlated with only a few native species.And their correlation strength and significance were all affected by specific species and flooded environment.In conclusion,our results suggest that the relative abundance of A.philoxeroides can more effectively explain the wetland community response to different invasion degrees than phylogenetic evenness,regardless of flooding.
基金Supported by the Tarbiat Moallem University,Iran
文摘Tailings of a Pb and Zn mine as a metal-contaminated area （Zone 1） with two pioneer plant species, Peganum harmala and Zygophyllum fabago, were investigated and compared with a non-contaminated area （Zone 2） in the vicinity. Total concentrations of Pb, Zn, and Cu in the soil of Zone 1 were 1 416, 2 217, and 426 mg kg-1, respectively, and all exceeded their ranges in the normal soils. The soil pH was in the neutral range and most of the physical and chemical characteristics of the soils from both zones were almost similar. The species Z. fabago accumulated higher Cu and Zn in its aerial part and roots than the normal plants. On the other hand, their concentrations did not reach the criteria that the species could be considered as a metal hyperaccumulator. The species P. harmala did not absorb metals in its roots; accordingly, the accumulation factor values of these metals were lower than 1. The contents of chlorophyll, biomass, malondialdehyde, and dityrosine in these two species did not vary significantly between the two zones studied. In Zone 1, leaf vacuoles of Z. fabago stored 35.6% and 43.2% of the total leaf Cu and Zn, respectively. However, in this species, the levels of phytochelatins （PCs） and glutathione （GSH） and antioxidant enzyme activities were significantly higher in Zone 1 than in Zone 2. In conclusion, metal exclusion in P. harmala and metal accumulation in Z. fabago were the basic strategies in the two studied pioneer species growing on the metal-contaminated zone. In response to metal stress, elevation in antioxidant enzyme activities, increases in the PCs and GSH levels in the aerial parts, and metal storage within vacuoles counteracted each other in the invasion mechanism of Z. ]abago.
