نتایج جستجو برای: lakes

تعداد نتایج: 17721  

Journal: :Remote Sensing 2017
Karolina Korzeniowska Oliver Korup

The Tibetan Plateau, the world’s largest orogenic plateau, hosts thousands of lakes that play prominent roles as water resources, environmental archives, and sources of natural hazards such as glacier lake outburst floods. Previous studies have reported that the size of lakes on the Tibetan Plateau has changed rapidly in recent years, possibly because of atmospheric warming. Tracking these chan...

Journal: :Environmental monitoring and assessment 2009
Anthony R Olsen Blaine D Snyder Leanne L Stahl Jennifer L Pitt

The National Lake Fish Tissue Study (NLFTS) was the first survey of fish contamination in lakes and reservoirs in the 48 conterminous states based on a probability survey design. This study included the largest set (268) of persistent, bioaccumulative, and toxic (PBT) chemicals ever studied in predator and bottom-dwelling fish species. The U.S. Environmental Protection Agency (USEPA) implemente...

2007
P. Rosén

Near infrared spectroscopy (NIRS), diatoms, pollen, charcoal, loss-on-ignition (LOI), and nutrient elements in lake sediments were used to assess important factors controlling Holocene changes in the total organic carbon (TOC) concentration, pCO2, color and pH of lake water in three boreal forest lakes in northern Sweden. The results suggest that mire formation, fire frequency and humidity are ...

2012
Jordan S. Read David P. Hamilton Ankur R. Desai Kevin C. Rose Sally MacIntyre John D. Lenters Robyn L. Smyth Paul C. Hanson Jonathan J. Cole Peter A. Staehr James A. Rusak Donald C. Pierson Justin D. Brookes Alo Laas Chin H. Wu

[1] High-frequency physical observations from 40 temperate lakes were used to examine the relative contributions of wind shear (u*) and convection (w*) to turbulence in the surface mixed layer. Seasonal patterns of u* and w* were dissimilar; u* was often highest in the spring, while w* increased throughout the summer to a maximum in early fall. Convection was a larger mixed-layer turbulence sou...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2015
Shengli Tao Jingyun Fang Xia Zhao Shuqing Zhao Haihua Shen Huifeng Hu Zhiyao Tang Zhiheng Wang Qinghua Guo

Lakes are widely distributed on the Mongolian Plateau and, as critical water sources, have sustained Mongolian pastures for hundreds of years. However, the plateau has experienced significant lake shrinkage and grassland degradation during the past several decades. To quantify the changes in all of the lakes on the plateau and the associated driving factors, we performed a satellite-based surve...

2017
J. M. Ramstack Sherilyn C. Fritz D. R. Engstrom S. A. Heiskary

Significant population growth over the last three decades, as well as efforts to improve surface-water quality mandated by the Clean Water Act, potentially have had opposing influences on aquatic ecosystems in the U.S. Because historical data on water-quality trends are limited over this time period, we developed a diatom-based transfer function to reconstruct chloride, color, acid neutralizing...

1999
NEIL F. LAIRD

Mesoscale vortices are one of several types of wintertime lake-effect structures that are observed over the Great Lakes region as cold arctic air is rapidly modified from below by warm lake waters. These vortices are thought to occur less frequently than other lake-effect structures, such as wind-parallel snowbands (e.g., Kristovich 1993), which are responsible for greater than half of the year...

2012
Michael T. Brett George B. Arhonditsis Sudeep Chandra Martin J. Kainz

Many studies have concluded terrestrial carbon inputs contribute 20-70% of the carbon supporting zooplankton and fish production in lakes. Conversely, it is also known that terrestrial carbon inputs are of very low nutritional quality and phytoplankton are strongly preferentially utilized by zooplankton. Because of its low quality, substantial terrestrial support of zooplankton production in la...

Journal: :Ecology 2009
James J Elser Marcia Kyle Laura Steger Koren R Nydick Jill S Baron

Atmospheric nitrogen (N) deposition to lakes and watersheds has been increasing steadily due to various anthropogenic activities. Because such anthropogenic N is widely distributed, even lakes relatively removed from direct human disturbance are potentially impacted. However, the effects of increased atmospheric N deposition on lakes are not well documented. We examined phytoplankton biomass, t...

2018
Alex Echeverría-Vega Guillermo Chong Antonio E. Serrano Mariela Guajardo Olga Encalada Victor Parro Yolanda Blanco Luis Rivas Kevin C. Rose Mercedes Moreno-Paz José A. Luque Nathalie A. Cabrol Cecilia S. Demergasso

Laguna Negra and Lo Encañado are two oligotrophic Andean lakes forming part of the system fed by meltwater from distinct glacial tongues of the Echaurren glacier in central Chile, which is in a recession period. The recent increase in temperature and decline in precipitation have led to an increase of glacial meltwater and sediments entering these lakes. Although the lacustrine systems are also...

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