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111.
Shifts in the spatio-temporal growth dynamics of shortleaf pine   总被引:2,自引:0,他引:2  
Previous studies focusing on the growth history of Pinus echinata at the edge of its geographical range have suggested that changes in growth correspond to climatic and non-climatic (e.g., anthropogenic) factors. We employ a regime-dependent state-space model that allows us to detect and characterize the changes in tree growth dynamics over space and time using readily available dendrochronological and climatic data in the presence of various sources of uncertainty. We utilize methods common in atmospheric sciences but relatively unknown in ecology and forestry to develop a hierarchical model for tree growth and describe the growth dynamics. The utility of such methods for addressing ecological problems will grow as more high dimensional spatio-temporal processes are considered and datasets become more readily available.  相似文献   
112.
介绍了当前国内利用碱性印染废水进行燃煤锅炉烟气湿法脱硫除尘的技术,并对其进行了技术经济分析。  相似文献   
113.
刘文奎 《火灾科学》1998,7(2):14-20
1990年以来,淮南矿区11个矿井共发生自燃火灾49起,自燃发火率平均为每百万吨习煤量0.53次。通过对该矿区井下煤炭自燃因素和地质条件及开采中出现的自燃发火原因作了具体分析,从中找出发火规律;并对井下煤层自燃发火采取均压通风和直接灭火做了新的尝试,提出了对井下煤炭自燃防治措施。  相似文献   
114.
用经济学的观点分析了其它防火要素的投入量不变,仅改变某种可变防火要素的投入时,减灾效益E、边际减灾效益EM、平均减灾效益E/Fi与单一可变防火要素Fi的关系。提出了如何采用连际分析的方法确定单一防火要素的最佳投入问题。  相似文献   
115.
Open-focused microwave-assisted extraction and ICP-OES determination of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn from surface sediments of the estuary of Bilbao (Basque Country, North of Spain) was carried out. All the samples were collected at three different tributaries of the estuary (Asua, Galindo and Nerbioi-Ibaizabal) every two months during 1999. The digestion procedure was proposed from the conclusions of a fractionated factorial design, and the precision and accuracy of the method was verified using a certified reference sediment (RTC008-050). The results of the analysis were statistically treated by means of principal component analysis and correlation analysis. The principal component analysis of sediment data (32 samples × 9 metals) indicated different patterns of contamination regarding the tributary and sampling station. The two main patterns observed were a steady increment of the metal concentration along all the campaigns in the samples collected in the Galindo River and a seasonal variation in the Nerbioi-Ibaizabal River, with higher metallic content during summertime and lower content during wintertime.  相似文献   
116.
浙江省生态环境可持续发展评价指标体系的建立   总被引:8,自引:0,他引:8  
生态环境的可持续发展评价是生态安全与生态建设中的重要内容。本研究应用主成分分析法,收集浙江省1990~2000年的数据,对评价指标进行初步筛选.同时采用德尔斐法进行专家咨询,得到评价指标的分层排序。最后从初选的54个评价指标中,根据主成分分析法、专家咨询法的指标筛选结果,结合有关国家及地方生态环境建设规划,建立了由40个指标组成的浙江省生态环境可持续发展评价指标体系。  相似文献   
117.
随着荧光分析技术和传感技术的发展,荧光化学传感器已经成为一种重要的连续分析测量装置.它具有很高的选择性和灵敏度,可以实现对pH、溶解氧、含氮化合物、有毒害重金属离子、有机污染物进行实时和在线测定,因此在环境分析监测方面具有广泛的应用前景.简要介绍了荧光化学传感器的原理、制备及分类,综述了近年来荧光化学传感器的发展及其在环境分析监测中的最新研究成果,并探讨了荧光化学传感器在环境分析监测领域的应用前景和发展方向.  相似文献   
118.
Sakurai T  Suzuki N  Morita M 《Chemosphere》2002,46(9-10):1359-1365
Past dioxin (coplanar polychlorinated biphenyl (Co-PCB), 2,3,7,8-substituted polychlorinated dibenzo-p-dioxin (PCDD) and 2,3,7,8-substituted polychlorinated dibenzofuran (PCDF)) fluxes recorded in dated aquatic-sediment cores were analyzed using principal component analysis (PCA). The data set consisted of samples from four cores collected from the Kanto region of Japan. Time trends and spatial differences in the dioxin flux were examined, and the potential relationship to emission sources was investigated. Twenty-five compounds and 58 core slices, corresponding to the later half of the 20th century, were subjected to the analysis. The PCA of both log-transformed and maximum-value-standardized data successfully divided the dioxin compounds into a small number of groups, and three similar clusters of Co-PCBs, PCDDs and penta- to hepta-CDFs were identified. PCB formulations used in the past are judged to have been responsible for the major part of the Co-PCB flux recorded in the sediment cores. However, the relationship to emission sources needs further investigation. It is suggested that most 2,3,7,8-substituted PCDDs and PCDFs are different from Co-PCBs in their emission sources or movements in the environment. The subcore clusters obtained from the PCA of log-transformed data show that the cores from different sampling areas exhibited distinct dioxin fluxes and compositions. Common time trends among the cores were more effectively summarized by the PCA of maximum-value-standardized data focusing on relative time trends. PC scores show that recently the flux of each dioxin compound in the four cores has been generally declining after having reached a peak.  相似文献   
119.
生态补偿机制目前是国内外研究的热点,生态建设补偿机制是生态补偿机制的重要组成部分。本文首先分析了生态建设补偿机制的内涵,研究构建了生态建设补偿机制的框架。  相似文献   
120.
针对水体中磺酸类有机化合物的分离分析,较为系统地总结了近年来国内外学者在磺酸类化合物检测方面所作的研究工作,主要介绍了高效液相色谱、气质联用和电位等检测方法的应用。  相似文献   
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