Using long-term datasets to study exotic plant invasions on rangelands in the western United States

Invasions by exotic species are generally described using a logistic growth curve divided into three phases: introduction, expansion and saturation. This model is constructed primarily from regional studies of plant invasions based on historical records and herbarium samples. The goal of this study is to compare invasion curves at the local scale to the logistic growth curve using long-term datasets. Five datasets ranging 41–86 years in length were recovered from five sites in four western states. Data for the following seven exotic species were analyzed using regression analysis to evaluate fit to a non-linear sigmoidal logistic curve: crested wheatgrass (Agropyron cristatum), dwarf alyssum (Alyssum desertorum), cheatgrass (Bromus tectorum), Lehmann lovegrass (Eragrostis lehmanniana), halogeton (Halogeton glomeratus), Russian thistle (Salsola tragus) and tumble mustard (Sisymbrium altissimum). A greater variety of curve shapes was documented by long-term datasets than those published based on herbaria sampling. Only two species from three different sites and with three different data types met the criteria for fitting a logistic curve. Many of the other species/location combinations were characterized by sporadic spikes and crashes. The general lack of fit with the model may be the results of the complex interactions that drive vegetation change in rangeland environments.     

准南前陆冲断带的油气输导体系与有利区预测

准南前陆冲断带油气资源丰富,但油气探明率较低,原因在于油气输导体系不清。通过对储集层、断裂和不整合面等构成油气输导体系的单一因素的发育特点的分析,阐明了每一种因素对油气输导过程的影响。准南前陆冲断带发育一套冲积扇一辫状河一辫状河三角洲．浅湖的沉积体系。储层具有较强的非均质性,相对高孔渗的砂体是油气运移的主要通道;该区发育上、下两套断裂体系,它们的组合形式为油气垂向快速运移提供了良好的输导条件;不整合面的发育为油气大规模的侧向运移提供了输导空间。     

油气成藏动力学研究方法与应用

油气成藏过程的动力学研究是以一期油气成藏过程中从油气源到油气藏的统一动力环境系统为单元,定量研究油气供源、运移、聚集的机理、控制因素和动力学过程。以此为基础有望解决油气成藏定量的动力学研究中的几个关键问题。输导层概念的提出及砂岩输导层模型基本工作程序的建立,形成了可以利用通常的物性参数进行输导层量化表征的方法,实现了对油气运移通道的量化表征; 采用断层连通概率的概念对各种参数表征断层开启性的能力进行比较和评价,探讨了各种地质参数的有效性和代表性,建立起了断层启闭性表征参数的评价方法; 采用数值模拟方法,耦合运聚动力与输导体系,实现成藏系统内油气运移过程的模拟分析; 以运移途中烃损失量估算为基础,建立新的物质平衡方法,以模拟获得的运移路径为线索,评估油气在研究不同方向上的运移聚集量,展现油气运移的路径特征、运移方向及运移量,初步形成了以油气成藏动力学成因为基础的油气资源预测方法。     

液液萃取-固相萃取富集地下水中毒杀芬的对比研究

应用液液萃取、固相萃取柱、固相萃取盘等传统和现代富集技术,对半挥发性有机物进行提取,建立了气相色谱-负化学电离质谱测定地下水中毒杀芬的方法。对性能较好的自制GDX-502固相萃取柱进行了条件优化。结果表明,使用填制的GDX-502固相萃取柱富集地下水中的毒杀芬,基体加标回收率为92.3%～98.5%,优于商品固相苯取柱LC-C18、ENVITM-C18以及固相萃取盘(92.8%～96.8%)和液液萃取(80.3%～88.5%);GDX-502固相萃取柱富集速度低于固相萃取盘,但远高于LC-C18和ENVITM-C18;GDX-502固相萃取柱的批量处理样品能力(12个)高于固相萃取盘(6个);同时所使用的有机试剂量远低于液液萃取。GDX-502固相萃取柱的萃取效率、分析通量、经济性和环保性具有更大的优势。     

新型有机-无机杂化涂层-气相色谱/质谱联用测定正构烷烃性能研究

水体中正构烷烃的含量反映了研究区域有机物污染水平.痕量正构烷烃的测定常常需要结合分离富集方法才能保证灵敏度和选择性,液液萃取等常规分离富集方法存在耗时长、有机溶剂使用量大等缺点,而新型固相微萃取(SPME)分离富集技术相比而言具有高效简便、富集效率高的特点.本文采用溶胶-凝胶法自制稳定性和耐基质性能更优的有机-无机杂化SPME涂层,结合气相色谱-质谱(GC - MS)检测技术,对水样中26种正构烷烃进行同时测定.在优化的SPME - GC/MS条件下,采用浸入式萃取方式,萃取温度为25℃,萃取时间为30 min,26种正构烷烃的分析信号与浓度之间有良好的线性关系(线性相关系数为0.9935 ～0.9999),方法检出限为0.011 ～0.085μg/L(k=3),相对标准偏差(RSD,n=5)为3.9％ ～10.0％.新型有机-无机杂化涂层与传统的分离富集技术相比,减少了有机溶剂的使用,提高了工作效率;与商用PDMS涂层相比,增加了正构烷烃同时检测的种类,提高了灵敏度,检出限低2～10倍.自制的有机-无机杂化SPME涂层体现出优异的分析性能和应用潜力.     

H2O content of deep-seated orogenic continental crust: the Ulten Zone,Italian Alps

To estimate the amount of H₂O stored at lower crustal levels after burial, we considered the pile of migmatitic paragneisses in the Variscan Ulten Zone as a case study area. We constructed a pseudosection in the system K₂O-Na₂O-CaO-FeO-MnO-MgO-Al₂O₃-SiO₂-TiO₂-H₂O for an average paragneiss, a relevant prograde PT path (8.5 kbar, 600°C; 11.5 kbar, 750°C; 14.0 kbar, 1000°C) and H₂O contents between 0 and 10 wt.%. Based on an assemblage of garnet?+?biotite?+?white mica?+?kyanite?+?20–30 vol.% former melt (now represented mainly by leucosomes composed of plagioclase?+?quartz), a bulk H₂O content of 3.2 ± 1.1 wt.% was estimated for a peak temperature ranging between 770 and 800°C. Before melting, somewhat less than 1.8 wt.% H₂O was stored in minerals. Thus, a considerable amount of H₂O must have either resided in pore spaces along grain boundaries or, much less likely, infiltrated the paragneisses from below. Evidently, significant quantities of H₂O as a free phase may be stored in buried sialic crust, resulting in considerable melting of deep-seated rocks during continent–continent collision.     

鄂尔多斯盆地富县地区延长组成岩相特征及控制因素

通过野外剖面、岩心观察、薄片鉴定,结合扫描电镜与能谱分析等测试手段,在充分认识富县地区长6、长8油层组储层特征、成岩作用基础上,研究长6、长8油层组成岩相类型.主要成岩相包括有泥岩强烈压实相、砂岩压实(压溶)相、砂岩剩余原生粒间孔隙-次生溶蚀孔隙相、砂岩次生溶蚀孔隙相和微裂缝相等5种类型.结合沉积环境及沉积相平面展布特征,阐述了成岩相平面分布,结合储层发育特征主控因素深入研究成岩相特征主控因素,表明沉积环境为成岩相特征提供了物质基础,沉积物在后期成岩演化过程中受成岩作用控制,即成岩相为沉积物在成岩演化后的具体体现.     

湿润中低山景观条件下土壤金属活动态找矿试验

对长江中下游成矿带内的城门山铜多金属矿床进行金属活动态找矿试验.结果表明,处于湿润中低山景观区的城门山矿区,上覆土壤中的Au主要以有机态形式存在,Cu主要以有机态和铁锰氧化物态形式存在,且在矿体上方它们的活动态率均达到30％以上,能较好的反映深部矿化信息.结合试验结果,在土壤测量中发现了城门山南侧的联盟银金矿化点.     

大地电磁测深视电阻率和相位曲线之间近似互算方法及程序实现

介绍了大地电磁测深曲线中视电阻率曲线和相位曲线之间互相近似推算的原理和方法,并给出基于MATLAB平台的主要实现代码,为实测视电阻率曲线和相位曲线的编辑和处理提供了一种近似参考依据。     

用于地震反射界面识别的瞬时相位复合属性

复地震道技术采用Hilbert变换通过求解实地震信号的解析信号,可将反映地震信号局部变化情况的地震波的瞬时振幅、瞬时相位和瞬时频率等信息分离开,瞬时相位是一种独立于地震振幅,并且不受其影响的地震属性参数,因此瞬时相位能更好地反映构造几何形态的细节.通过理论模型分析发现,瞬时振幅与极性反转前后地震记录的瞬时相位一阶差分之和进行加权,得到的复合属性可以较为准确、可靠地识别地震反射界面的位置,具有较好的应用效果.