Bauxite mining will bring huge economic benefit,but it also faces the risk of environmental pollution.Metal pollution problem has been widely concerned in bauxite tailing areas.Biodiversity indices,metal concentration...Bauxite mining will bring huge economic benefit,but it also faces the risk of environmental pollution.Metal pollution problem has been widely concerned in bauxite tailing areas.Biodiversity indices,metal concentrations of moss crusts,and soil contamination indices in Wachangping bauxite tailing areas in Guizhou Province,China were measured and analyzed.In a total of 40 species belonging to 19 genera and 12 families of moss in the study areas,Ditrichum flexicaule(Schwaegr.)Hamp.(DF),Oxystegus cylindricus(Brid.)Hilp.(OC),and Ditrichum brevidens Nog.(DB)are the dominant moss crusts.Moss species diversity in different habitats has a certain regularity:waste residues area<waste rocks area<ore stockpile area<slope shrub area<shrub area by gutter<slope shrub herbaceous area.Sorenson diversity index(β)of moss species is influenced by microenvironment and substrate.Concentrations of Al,Mg,Ca,Fe,K,and Ti are the largest in DB(2,990 to 73,210 mg kg^(-1)),followed by those in DF(2,900 to 61,890 mg kg^(-1)),and are the smallest in OC(690 to 32,240 mg kg^(-1)),which show that the three moss crusts have different bioaccumulation capacities.Metal contents in underlying soils of moss crusts are higher than the background levels.Bioaccumulation factor(BAF)of Al,Mg,Ca,Fe,and K in three moss crusts are decreased in the following order:DB>DF>OC.Single factor pollution index(Ps)and Nemero comprehensive pollution index(Pc)of six metal are much greater than 3,and the index of geoaccumulation(Igeo)(1geo<5)reveals that the soil environment is at moderately to seriously contaminated levels.Principal components analysis(PCA)shows that there is no significant correlation between p H value,and metal contents(Al,Mg,Fe,K and Ti),soil temperature(ST)and metal contents(Al,Mg,Fe,K and Ti).Soil humidity(SH)is negatively correlated with metal contents(Al,Mg,Fe,K and Ti).These three environmental factors have little effect on the distribution of metal.Result also reflects that DB moss is readily able to both tolerate and accumulate metal,which makes it a suitable bioindicator of multiple metal contamination in Wachangping bauxite tailing areas.展开更多
采用随机方法分析了蕴含轴向流动流体的BTA(boring and trepanning association)深孔镗杆在随机力下的横向随机动力行为。建模时考察了流固耦合镗杆承受的弯曲、拉伸和扭转变形;经Galerkin Method离散化处理,分析了BTA镗杆在有、无随机...采用随机方法分析了蕴含轴向流动流体的BTA(boring and trepanning association)深孔镗杆在随机力下的横向随机动力行为。建模时考察了流固耦合镗杆承受的弯曲、拉伸和扭转变形;经Galerkin Method离散化处理,分析了BTA镗杆在有、无随机激励两种情况的特征值和特征频率对振动特性的影响;利用响应方差最大值和谱密度解析了BTA镗杆横向振动的临界转速与临界失稳频率;明确了镗杆随转速、刚度、初始轴向总力和剪切模量等参数变化对系统振动特性的影响机制:镗杆转速变化对系统稳定性不再具有单调性,随BTA镗杆转速持续增加,系统可历经两次转速的临界失稳,相继出现二次失稳和二次稳定;增加系统等效刚度和等效剪切模量会促进工作过程的稳定,改变轴向力对工作过程稳定的影响不明显;并以随机振动物理试验信号的功率谱分析,验证了理论仿真结果与试验结果的一致性。该研究在一定程度上揭示了BTA深孔工艺系统运动状态的复杂性,这种研究模式为进一步分析在复杂状态下的运动演化提供了更多的可能。研究结论为更好地理解BTA深孔镗杆工作时的随机动力行为提供了依据,也为BTA深孔工艺过程的振动控制和参数优化奠定了理论基础。展开更多
基金the National Natural Science Foundation of China(NSFC No.32360309)。
文摘Bauxite mining will bring huge economic benefit,but it also faces the risk of environmental pollution.Metal pollution problem has been widely concerned in bauxite tailing areas.Biodiversity indices,metal concentrations of moss crusts,and soil contamination indices in Wachangping bauxite tailing areas in Guizhou Province,China were measured and analyzed.In a total of 40 species belonging to 19 genera and 12 families of moss in the study areas,Ditrichum flexicaule(Schwaegr.)Hamp.(DF),Oxystegus cylindricus(Brid.)Hilp.(OC),and Ditrichum brevidens Nog.(DB)are the dominant moss crusts.Moss species diversity in different habitats has a certain regularity:waste residues area<waste rocks area<ore stockpile area<slope shrub area<shrub area by gutter<slope shrub herbaceous area.Sorenson diversity index(β)of moss species is influenced by microenvironment and substrate.Concentrations of Al,Mg,Ca,Fe,K,and Ti are the largest in DB(2,990 to 73,210 mg kg^(-1)),followed by those in DF(2,900 to 61,890 mg kg^(-1)),and are the smallest in OC(690 to 32,240 mg kg^(-1)),which show that the three moss crusts have different bioaccumulation capacities.Metal contents in underlying soils of moss crusts are higher than the background levels.Bioaccumulation factor(BAF)of Al,Mg,Ca,Fe,and K in three moss crusts are decreased in the following order:DB>DF>OC.Single factor pollution index(Ps)and Nemero comprehensive pollution index(Pc)of six metal are much greater than 3,and the index of geoaccumulation(Igeo)(1geo<5)reveals that the soil environment is at moderately to seriously contaminated levels.Principal components analysis(PCA)shows that there is no significant correlation between p H value,and metal contents(Al,Mg,Fe,K and Ti),soil temperature(ST)and metal contents(Al,Mg,Fe,K and Ti).Soil humidity(SH)is negatively correlated with metal contents(Al,Mg,Fe,K and Ti).These three environmental factors have little effect on the distribution of metal.Result also reflects that DB moss is readily able to both tolerate and accumulate metal,which makes it a suitable bioindicator of multiple metal contamination in Wachangping bauxite tailing areas.
文摘采用随机方法分析了蕴含轴向流动流体的BTA(boring and trepanning association)深孔镗杆在随机力下的横向随机动力行为。建模时考察了流固耦合镗杆承受的弯曲、拉伸和扭转变形;经Galerkin Method离散化处理,分析了BTA镗杆在有、无随机激励两种情况的特征值和特征频率对振动特性的影响;利用响应方差最大值和谱密度解析了BTA镗杆横向振动的临界转速与临界失稳频率;明确了镗杆随转速、刚度、初始轴向总力和剪切模量等参数变化对系统振动特性的影响机制:镗杆转速变化对系统稳定性不再具有单调性,随BTA镗杆转速持续增加,系统可历经两次转速的临界失稳,相继出现二次失稳和二次稳定;增加系统等效刚度和等效剪切模量会促进工作过程的稳定,改变轴向力对工作过程稳定的影响不明显;并以随机振动物理试验信号的功率谱分析,验证了理论仿真结果与试验结果的一致性。该研究在一定程度上揭示了BTA深孔工艺系统运动状态的复杂性,这种研究模式为进一步分析在复杂状态下的运动演化提供了更多的可能。研究结论为更好地理解BTA深孔镗杆工作时的随机动力行为提供了依据,也为BTA深孔工艺过程的振动控制和参数优化奠定了理论基础。
