Sampling strategies to evaluate the status of offshore soft sediment assemblages     

Rogers SI  Somerfield PJ  Schratzberger M  Warwick R  Maxwell TA  Ellis JR 《Marine pollution bulletin》2008,56(5):880-894

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Effects of changing land use on the microbial water quality of tidal creeks     

DiDonato GT  Stewart JR  Sanger DM  Robinson BJ  Thompson BC  Holland AF  Van Dolah RF 《Marine pollution bulletin》2009,58(1):97-106

Population growth along the southeastern United States coast has precipitated the conversion of forested watersheds to suburban and urban ones. This study sampled creeks representing forested, suburban, and urban watersheds along a longitudinal gradient for indicators of water quality, including traditional indicator bacteria (fecal coliforms and enterococci) and alternative viral indicators (male-specific and somatic coliphages). Tested microorganisms were generally distributed with highest concentrations in creek headwaters and in more developed watersheds. The headwaters also showed the strongest predictive relationship between indicator concentrations and urbanization as measured by impervious cover. A seasonal pattern was observed for indicator bacteria but not for indicator viruses. Coliphage typing indicated the likely source of contamination was nonhuman. Results suggest that headwater creeks can serve as sentinel habitat, signaling early warning of public health concerns from land-based anthropogenic activities. This study also implies the potential to eventually forecast indicator concentrations under land use change scenarios.  相似文献   

PRESENT　SITUATION，FEATURE　AND　DEVELOPMENTAL　IDEAS　OF　BORDER　OPENING　IN　XINJIANG     

谢香方  李春华 《中国地理科学(英文版)》1995,5(3):212-221

ＰＲＥＳＥＮＴＳＩＴＵＡＴＩＯＮ，ＦＥＡＴＵＲＥＡＮＤＤＥＶＥＬＯＰＭＥＮＴＡＬ　ＩＤＥＡＳＯＦＢＯＲＤＥＲＯＰＥＮＩＮＧＩＮＸＩＮＪＩＡＮＧＸｉｅＸｉａｎｇｆａｎｇ（谢香方）；ＬｉＣｈｕｎｈｕａ（李春华）（ＸｉｎｊｉａｎｇＩｎｓｔｉｔｕｔｅｏｆＧｅ...  相似文献   

金属成矿过程中的有机质：研究进展与展望   总被引：1，自引：0，他引：1  

Disn.  JR 刘金钟 《地质地球化学》1992,(3):7-16

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Triton: topside ionosphere and nitrogen escape     

Yung YL  Lyons JR 《Geophysical research letters》1990,17(10):1717-1720

The principal ion in the ionosphere of Triton is N+. Energetic electrons of magnetospheric origin are the primary source of ionization, with a smaller contribution due to photoionization. To explain the topside plasma scale height, we postulate that N+ ions escape from Triton. The loss rate is 3.4 x 10(7) cm-2 s-1 or 7.9 x 10(24) ions s-1. Dissociative recombination of N2+ produces neutral exothermic fragments that can escape from Triton. The rate is estimated to be 8.6 x 10(6) N cm-2 s-1 or 2.0 x 10(24) atoms s-1. Implications for the magnetosphere of Neptune and Triton's evolution are discussed.  相似文献   

Primary production of the cryptoendolithic microbiota from the Antarctic Desert     

Vestal JR 《Polarforschung》1988,58(2-3):193-198

Primary production in the Antarctic cryptoendolithic microbiota can be determined from biomass and photosynthetic 14CO2 incorporation measurements. Even though good nanoclimate data are available, it is difficult to determine the amount of time when abiotic conditions permit metabolism. Making appropriate assumptions concerning the metabolism of the cryptoendolithic microbiota during periods of warmth, light and moisture, the primary production of the biota was calculated to be on the order of 0.108 to 4.41 mgC/m2/yr, with a carbon turnover time from 576 to 23,520 years. These production values are the lowest found on planet Earth.  相似文献   

基于可持续发展思想的县域城镇体系规划   总被引：14，自引：3，他引：14  

张小雷  李春华 《干旱区地理》1997,20(2):1-8

探讨可持续发展思想与城镇体系规划的关系，以新疆库车县为例，分析县域城镇体系规划中如何体现这一基本思想，以促进以城镇为中心的县域社会、经济、环境的协调有序发展。  相似文献   

Lost Hills油田减饱和带的确定及其对蒸汽驱开发...     

Kerns  JR 周征 《国外石油地质》1992,(2):68-77

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美国南阿帕拉契亚晚古生代上冲地体的复原再造     

JR.  R.D.Hatcher  刘永江 《世界地质》1991,(1)

阿帕拉契亚造山带经历了早中古生代期间的增生历史,并伴有变形作用、变质作用和深成岩浆侵入作用。早中古生代期间形成的构造在二叠纪与非洲大陆碰撞期间,被阿勒格尼逆冲断层所切割。该逆冲断层从碰撞带下部的韧一脆性过渡带依次进入晚元古代和古生代裂谷边缘和地台,其上的构造迁移主要向北美内陆,但阿勒格尼走向滑移构造域也在包括主要为右行运动的内构造带中形成。有些地区(东部山麓)的右行位移明  相似文献   

分数维与节理粗糙度     

Carr  JR 陈浩东 《水文地质工程地质译丛》1991,(2):28-34

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