Exploring the effects of urban and agricultural land use on surface water chemistry,across a regional watershed,using multivariate statistics     

M.L. Fitzpatrick  D.T. Long  B.C. Pijanowski 《Applied Geochemistry》2007

In this paper, the influence of anthropogenic activity on surface water chemistry is investigated. Base flow samples from dominant land use streams in the Muskegon River Watershed, Michigan, USA, were analyzed for nutrients, major ions, and trace elements. Principal component and hierarchical cluster analysis were used to investigate the processes controlling the effects of land use on the biogeochemistry of streams in this Watershed. Biogeochemical fingerprints of land use were developed based on the results of the cluster analysis. Spider diagrams which referenced the natural environment aided the identification of the individual contributions of urban and agricultural land uses to surface water chemistry. The biogeochemical fingerprints quantified support previous findings (Urb: Na, K, Cl/Ag: Ca, Mg) and produced new insights into the effects of land use on the behavior of nutrients (Ag: N and Urb: N, P) and trace elements (Urb: V, Cr, Co, Cu, Se, Rb, Mo, Sr, Cd, Pb and Ba/Ag: U and As). The higher correlations of urban than agricultural land uses with nutrients, specifically P, were not expected and may reflect the effects of fertilization and wastewater or the season the samples were taken. More study in different geologic and urban settings is needed to help refine these fingerprints, but it is becoming apparent that despite obscuring factors, land use produces consistent, quantifiable associations between biogeochemical analytes.  相似文献   

南海夏季风爆发早晚的越赤道气流特征   总被引：1，自引：0，他引：1  

覃志年  金龙何慧 《广西气象》2007,28(3):8-11

根据国家气候中心提供的南海夏季风爆发期典型偏早（1966、1972、1996、2000、2001年）和偏晚年份（1970、1973、1987、1989、1991年）,利用ECMW F再分析1-5月逐日经向风资料,计算5个通道越赤道气流和越赤道乞流总量的距平值;探讨越赤道气流与南海夏季风爆发早晚的关系与特征。为预测南海夏季风爆发早晚提供判据。  相似文献   

动力延伸预报产品在广西月降水预报中的应用   总被引：1，自引：0，他引：1       下载免费PDF全文

何慧金龙  覃志年陈见 《应用气象学报》2007,18(5):727-731

利用1958—2005年NCEP/NCAR再分析资料和2003—2005年国家气候中心的动力延伸预报产品, 运用自然正交函数展开 (EOF) 求取预报关键区内的空间特征向量及其时间系数, 结合相似离度方法查找与预报月份相似的个例, 进而作出广西月降水量预报。独立样本试验证明, 利用动力延伸预报产品制作的区域月降水预报比利用前期实况高度距平场相关区域制作的预报效果更好。  相似文献   

滇西地区小地震群特征     

龙晓帆  王绍晋  陈立德  张喜玲  陈燕  罗淑进 《华北地震科学》1998,16(1):30-35

根据滇西地区（23°．8－28°N;97°．0－101°．5E）1966年1月－1996年7月89个ML≤4．7的小地震震群资料分别总结出滇西地区H,K,U,η,b,△M参数的判别指标和地区特征。着重讨论了小地震震群与云南及邻区中强震关系,以及综合利用上述参数尝试预报未来中强震。  相似文献   

A hybrid discrete-continuum approach to model hydro-mechanical behaviour of jointed rocks     

Lingli Wei  John A. Hudson 《Engineering Geology》1998,49(3-4):317-325

A hybrid discrete-continuum approach has been presented in this paper to simulate water flow in the near and far fields of deformable fractured rocks. In the near field, the discrete model is used; while in the far field, the equivalent continuum model is employed. The discrete element method (with the static relaxation algorithm) is used in the near field and the boundary integral equation method in the far field. Along the interface of these two domains, both mechanical and hydraulic compatibility conditions are satisfied. Fully coupled hydro-mechanical analysis can be conducted in the combined near and far fields. Application to a dam foundation problem has demonstrated the capability of the developed approach.  相似文献   

四湖排水系统运行规划优化模型   总被引：1，自引：0，他引：1       下载免费PDF全文

龙子泉  欧光华 《水科学进展》1998,9(3):237-244

分析了四湖排水系统的运行特点,应用大系统理论对系统进行了递阶分析并确定了该系统运行规划的NLP/DP/LP优化模型结构。在确定系统运行规则的基础上,分层建立了系统运行规划优化模型。  相似文献   

High-resolution ion-microprobe measurement of lead isotopes: Variations within single zircons from Lac Seul,northwestern Ontario     

R.W. Hinton  J.V.P. Long 《Earth and Planetary Science Letters》1979,45(2):309-325

Selected-area measurements of lead-isotope ratios in zircons have been made at high mass resolution using a modified A.E.I. IM20 ion-microprobe. At a working resolution of 3200 it is shown that the important interfering molecular peaks generated from the zircon matrix may be separated from atomic lead peaks. Corrections for overlapping peaks, which are necessary in measurements of lead isotopes at low mass resolution, are then only required for ²⁰⁸Pb.Measurements on N.B.S. standards show no isotope discrimination within counting statistics. Determination of ²⁰⁷Pb/²⁰⁶Pb on 29 single zircon grains from a tonalite gneiss and a granite from Lac Seul, northwestern Ontario, give very variable ratios with mean values close to those of bulk separates. Peaks in the distribution of 207/206 ratios obtained from the tonalite gneiss may be interpreted as evidence for two stages of lead loss. High 207/206 ratios are shown to be significant for at least two zircons and probably record a minimum age of formation of 3.3 ± 0.1 b.y. for the gneiss.  相似文献   

The specification of wide-band recorders     

R.E. Long 《Physics of the Earth and Planetary Interiors》1979,18(2):51-57

Working models for signal, path and earth-noise characteristics are developed which collectively define the input expected to a seismic recorder. These are used to elucidate the problems of frequency and dynamic ranges of wide-band recorders designed to record the whole body-wave signal received above earth noise. An optimised recorder characteristic is derived which minimises dynamic range.  相似文献   

Rb-Sr dating of Paleozoic glauconite from the Llano region,central Texas     

John P. Morton  Leon E. Long 《Geochimica et cosmochimica acta》1980,44(5):663-672

Glauconite from eight stratigraphic horizons (Cambrian to Pennsylvanian) in the Llano Uplift, central Texas and two Cretaceous glauconites were analyzed by the Rb-Sr method. Only two untreated samples provide ages in agreement with those anticipated from current best estimates of the geologic time scale. With one exception all the other apparent ages fall short of the estimated age of deposition by as much as 22%. Low ages, the pattern customarily observed, are attributed to postdepositional loss of radiogenic ⁸⁷Sr from expandable layers by weathering or during diagenesis.Detailed leaching experiments using a variety of reagents were performed to characterize the behavior of glauconite. The most promising treatment, which we recommend as standard procedure in all future studies, is with ammonium acetate which is able to purge the mineral of loosely-bound Rb and Sr while leaving tightly-bound components intact. After appropriate leach, three other Rb-Sr ages were brought into coincidence with their estimated ages of deposition.In contrast an Upper Cambrian glauconite was found to be extremely resistant to further alteration by chemical attack′, providing an age of 429 ± 17 M yr. Although 17% short of the age of deposition, this age is interpreted as the time of a real event: diagenetic recrystallization induced by burial. Comparison of data from four samples indicates that for Paleozoic glauconite, conditions exist in which the Rb-Sr system is less susceptible to mild disturbance than is the K-Ar system.  相似文献   

B. Le Mehaute, An introduction to hydrodynamics in water waves, Springer, Berlin (1976), p. 311 DM 60.60 or U.S. $24.80.     

R.R. Long 《Dynamics of Atmospheres and Oceans》1978,2(4)

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