نتایج جستجو برای: rivers

تعداد نتایج: 19001  

2015
Molly Lipscomb Ahmed Mushfiq Mobarak

Decentralization can improve service delivery, but it can also generate externalities across jurisdictional boundaries. We examine the nature and size of water pollution externalities as rivers flow across jurisdictions. Panel data on water pollution in Brazilian rivers coupled with county splits that change the locations of borders allow us to identify the spatial patterns of pollution as rive...

2015
Carley E. Iles Gabriele C. Hegerl

Following large explosive volcanic eruptions precipitation decreases over much of the globe1-6, particularly in climatologically wet regions4,5. Stratospheric volcanic aerosols reflect sunlight, which reduces evaporation, whilst surface cooling stabilises the atmosphere and reduces its water-holding capacity7. Circulation changes modulate this global precipitation reduction on regional scales1,...

Journal: :Journal of environmental sciences 2018
Bin Qu Mika Sillanpää Shichang Kang Fangping Yan Zhiguo Li Hongbo Zhang Chaoliu Li

Rivers are critical links in the carbon and nitrogen cycle in aquatic, terrestrial, and atmospheric environments. Here riverine carbon and nitrogen exports in nine large rivers on the Tibetan Plateau - the "Water Tower of Asia" - were investigated in the monsoon season from 2013 to 2015. Compared with the world average, concentrations of dissolved inorganic carbon (DIC, 30.7mg/L) were high in r...

2008
ZHANG Lijuan HUANG Wei JIANG Jie

River length has been the particular interest of people. Topographic data, which are obtained from field survey or digitizing from topographies, can serve as ideal data source for river length calculating. The topographic data are vector-based data, which represent river entities as polygonal line. Depending on data scale, rivers are represented in topographic data as single-line (narrow) or do...

Journal: :Environmental management 2005
Andrea J Radwell Thomas J Kwak

Preservation of extraordinary natural resources, protection of water quality, and restoration of impaired waters require a strategy to identify and protect least-disturbed streams and rivers. We applied two objective, quantitative methods to determine stream ecological integrity of headwater reaches of 10 Ozark rivers, 5 with Wild and Scenic River federal protective status. Thirty-four variable...

Journal: :Chemosphere 2007
Jun Yang Wenjing Zhang Yunfen Shen Weisong Feng Xinhua Wang

Polyurethane foam unit (PFU) systems were collected from 11 lakes and three rivers in the Yunnan Plateau, China and, the PFU extrusion liquids were analyzed for organochlorine pesticides (OCPs) by gas chromatography with electron capture detection (GC-ECD). The concentrations of pp'-DDE, HCB and HCHs were undetectable to 1.86 microgl-1 (mean 0.27 microgl-1), undetectable to 0.72 microgl-1 (mean...

Journal: :Water research 2011
Dong Li Rong Qi Min Yang Yu Zhang Tao Yu

To investigate bacterial community characteristics under long-term antibiotic selection pressures, water samples from the upstream and the downstream sections of two rivers individually receiving the treated penicillin G and oxytetracycline production wastewater, as well as the anaerobic and the aerobic effluent of the penicillin G production wastewater treatment plant, were taken and analyzed....

Journal: :The Science of the total environment 2002
D J Gilvear K V Heal A Stephen

Hydrology is a primary control on the ecological quality of river systems, through its influence on flow, channel geomorphology, water quality and habitat availability. Scottish rivers are widely perceived to be of high ecological quality, with abundant flow volumes and high water quality. However, historical and current river flow regulations, and land use change have altered the physical and ...

2018
Mohamadreza Masoudinejad Mansour Ghaderpoori Ahmad Zarei Jamal Nasehifar Alireza Malekzadeh Jalil Nasiri Afshin Ghaderpoury

Due to the great possibility of water contamination of many rivers by human activities in Iran, the study of water quality is crucial for water resource protection and human health. High level of phosphorous is the main reason for eutrophication of freshwater systems. The main aim of this study was to investigate the concentration of phosphorus in the rivers feeding into Taham dam in Zanjan, us...

Journal: :J. Systems Science & Complexity 2006
Jing He Xikang Chen Yong Shi

China is experiencing from serious water issues. There are many differences among the Nine Major Rivers basins of China in the construction of dikes, reservoirs, floodgates, flood discharge projects, flood diversion projects, water ecological construction, water conservancy management, etc. The shadow prices of water resources for Nine Major Rivers can provide suggestions to the Chinese governm...

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