نتایج جستجو برای: bottom sediment

تعداد نتایج: 94716  

Journal: :pollution 2015
akhil p.s. sujatha h

a comprehensive evaluation of the residual levels of organochlorine insecticides (ocis) in the sediment cores of cochin estuarine system (ces) is highlighted in this research article. it assessed the distribution pattern and impact of these xenobiotics in this environmental niche. fifteen persistent organochlorine compounds (ocs) were quantitatively analysed in the six sediment core samples col...

2010
Jaak Heinloo Aleksander Toompuu

The paper suggests a stationary model of the vertical distribution of the concentration of suspended sediment in the bottom layer of a natural water body with a flat bottom. The model explains the concentration distribution, formed jointly by the settling of suspended particles and turbulent diffusion. The flow is assumed geostrophic above the bottom-influenced layer, while in the bottom layer ...

Journal: :The Biological bulletin 1995
M Ilan A Abelson

Infaunal soft-bottom invertebrates benefit from the presence of sediment, but sedimentation is potentially harmful for hard-bottom dwellers. Most sponges live on hard bottom, but on coral reefs in the Red Sea, the species Biemna ehrenbergi (Keller, 1889) is found exclusively in soft-bottom lagoons, usually in the shallowest part. This location is a sink environment, which increases the depositi...

Journal: :The Journal of the Acoustical Society of America 2014
Caglar Yardim Peter Gerstoft William S Hodgkiss James Traer

Surface generated ambient noise can be used to infer sediment properties. Here, a passive geoacoustic inversion method that uses noise recorded by a drifting vertical array is adopted. The array is steered using beamforming to compute the noise arriving at the array from various directions. This information is used in two different ways: Coherently (cross-correlation of upward/downward propagat...

2017
Magdalena Strzebońska Elżbieta Jarosz-Krzemińska Ewa Adamiec

Research was conducted on the most polluted river system in Poland, impacted by active and historical mining. Bottom sediment, suspended particulate matter and river water were collected in 2014 from Przemsza river and its tributaries. Sampling points remained the same as those chosen in a 1995 study. This allowed the comparison of heavy metal accumulation in bottom sediment over a span of almo...

2014
J. C. Harris S. T. Grilli

Wave-induced boundary layer (BL) flows over sandy rippled bottoms are studied using a numerical model that applies a one-way coupling of a “far-field” inviscid flow model to a “near-field” large eddy simulation (LES) Navier– Stokes (NS) model. The incident inviscid velocity and pressure fields force the LES, in which near-field, wave-induced, turbulent bottom BL flows are simulated. A sediment ...

Journal: :Computers & Geosciences 2008
John C. Warner Christopher R. Sherwood Richard P. Signell Courtney K. Harris Hernan G. Arango

We are developing a three-dimensional numerical model that implements algorithms for sediment transport and evolution of bottom morphology in the coastal-circulation model Regional Ocean Modeling System (ROMS v3.0), and provides a two-way link between ROMS and the wave model Simulating Waves in the Nearshore (SWAN) via the ModelCoupling Toolkit. The coupled model is applicable for fluvial, estu...

2014
Kaipo Perez Kuʻulei S. Rodgers Paul L. Jokiel Claire V. Lager Daniel J. Lager

Survival and settlement of Pocillopora damicornis larvae on hard surfaces covered with fine (<63 µm) terrigenous red clay was measured in laboratory Petri dishes. The dishes were prepared with sediment films of various thicknesses covering the bottoms. Coral larvae were incubated in the dishes for two weeks and the percent that settled on the bottom was determined. There was a statistically sig...

Journal: :Journal of environmental quality 2005
B E Haggard P A Moore P B Delaune

Phosphorus inputs into reservoirs include external sources from the watershed and internal sources from the reservoir bottom sediments. This study quantified sediment P flux in Lake Eucha, northeastern Oklahoma, USA, and evaluated the effectiveness of chemical treatment to reduce sediment P flux. Six intact sediment-water columns were collected from three sites in Lake Eucha near the reservoir ...

ژورنال: آبخیزداری ایران 2019

The accumulation of sediments in reservoirs of dams has always been one of the problems of reservoir dams. Accordingly, one of the approaches to address this problem can be referred to as the method of pressure flushing. In this method, during the course of flushing, generally the bottom drainage outlets of the dam are opened for a certain period of time and the reservoir water level is kept al...

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