نتایج جستجو برای: sediment source

تعداد نتایج: 452323  

Journal: :journal of agricultural science and technology 2010
s. k. mirnia s. a. kowsar

the artificial recharge of groundwater (arg), where practicable, is an easy and economical method for desertification control in the arid and semi-arid zones where overpumping has critically lowered the watertable. although desiltation of floodwaters, which is a prerequisite for the arg, leads to rehabilitation of the eroded sites that house the sedimentation basins (sbs), the gradual imper...

2006
Carlos E. Ramos-Scharrón Lee H. MacDonald

Unpaved roads are believed to be the primary source of terrigenous sediments being delivered to marine ecosystems around the island of St John in the eastern Caribbean. The objectives of this study were to: (1) measure runoff and suspended sediment yields from a road segment; (2) develop and test two event-based runoff and sediment prediction models; and (3) compare the predicted sediment yield...

Journal: :Journal of environmental science and health. Part A, Toxic/hazardous substances & environmental engineering 2008
R D Delaune R P Gambrell Aroon Jugsujinda Istavan Devai Aixin Hou

Concentration of total Hg, methyl Hg, and other heavy metals were determined in sediment collected along a salinity gradient in a Louisiana Gulf Coast estuary. Surface sediment was collected at established coordinates (n = 292) along a salinity gradient covering Lake Maurepas, Lake Pontchartrain, Lake Borgne and the Chandeleur Sound located in the 12,170 km(2) Pontchartrain basin estuary southe...

2008
F. E. Rhoton W. E. Emmerich

Soil Sci. Soc. Am. J. 72:1102-1112 doi:10.2136/sssaj2007.0066 Received 15 Feb. 2007. *Corresponding author ([email protected]). © Soil Science Society of America 677 S. Segoe Rd. Madison WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information ...

2011
Subramaniam D. Rajan

Modal dispersion data i.e. mode arrival time as a function of frequency have been used in inversion schemes that estimate sediment properties in a range-independent environment. This method has now been extended to include range-dependent environment. Simulation studies show that range-dependent sediment properties can be extracted if modal dispersion data are obtained for multiple source/recei...

Journal: :Biochemical Society transactions 2011
Bonnie Laverock Jack A Gilbert Karen Tait A Mark Osborn Steve Widdicombe

Sediments play a key role in the marine nitrogen cycle and can act either as a source or a sink of biologically available (fixed) nitrogen. This cycling is driven by a number of microbial remineralization reactions, many of which occur across the oxic/anoxic interface near the sediment surface. The presence and activity of large burrowing macrofauna (bioturbators) in the sediment can significan...

Journal: :Environmental science & technology 2011
Patrick Belmont Karen B Gran Shawn P Schottler Peter R Wilcock Stephanie S Day Carrie Jennings J Wesley Lauer Enrica Viparelli Jane K Willenbring Daniel R Engstrom Gary Parker

Although sediment is a natural constituent of rivers, excess loading to rivers and streams is a leading cause of impairment and biodiversity loss. Remedial actions require identification of the sources and mechanisms of sediment supply. This task is complicated by the scale and complexity of large watersheds as well as changes in climate and land use that alter the drivers of sediment supply. P...

2018
Christopher L Dutton Amanda L Subalusky Shimon C Anisfeld Laban Njoroge Emma J Rosi David M Post

The Mara River Basin in East Africa is a trans-boundary basin of international significance experiencing excessive levels of sediment loads. Sediment levels in this river are extremely high (turbidities as high as 6,000 NTU) and appear to be increasing over time. Large wildlife populations, unregulated livestock grazing, and agricultural land conversion are all potential factors increasing sedi...

2013
Yuan Yao Enlou Zhang Nikolaus Kuhn Richard Jones Peter Langdon Ji Shen Philip Greenwood

Composite fingerprinting represents an effective method of reconstructing sediment-source changes in remote areas where long-term hydrological and sediment accretion records do not exist. A ca. 50-year record of sediment deposition was determined for a small catchment at Shudu, situated in northwest Yunnan Province, China. Woodland, pasture, shrubland and channel bank material are identified as...

2015
Richard B. Coffin Christopher L. Osburn Rebecca E. Plummer Joseph P. Smith Paula S. Rose Kenneth S. Grabowski Enrico Sciubba

Coastal methane hydrate deposits are globally abundant. There is a need to understand the deep sediment sourced methane energy contribution to shallow sediment carbon relative to terrestrial sources and phytoplankton. Shallow sediment and porewater samples were collected from Atwater Valley, Texas-Louisiana Shelf, Gulf of Mexico near a seafloor mound feature identified in geophysical surveys as...

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