نتایج جستجو برای: surface sediments

تعداد نتایج: 658804  

2014
Javed Iqbal Munir H Shah

Background: The present study was carried out to assess the seasonal variations, source apportionment, and risk assessment of heavy metals (Cd, Cr, Cu, Fe, Mn, Pb, and Zn) in the surface sediments from the Khanpur Lake, Pakistan. Methods: Composite samples are collected and processed to measure the concentrations of heavy metals in Ca(NO3)2 extract and acid extract of the sediments using flame ...

Journal: :Philosophical transactions of the Royal Society of London. Series B, Biological sciences 2015
Franz Hölker Christian Wurzbacher Carsten Weißenborn Michael T Monaghan Stephanie I J Holzhauer Katrin Premke

An increasing proportion of the Earth's surface is illuminated at night. In aquatic ecosystems, artificial light at night (ALAN) may influence microbial communities living in the sediments. These communities are highly diverse and play an important role in the global carbon cycle. We combined field and laboratory experiments using sediments from an agricultural drainage system to examine how AL...

1999
Timothy G. Ferdelman Henrik Fossing Kirsten Neumann Horst D. Schulz

Sulfate reduction rates in the surface sediments from 17 stations from an along-slope transect (1,300 m) and from a cross-slope transect (855–4,766 m) were determined in the continental margin sediments of the Benguela Upwelling system. Profiles at all sites in the upwelling area showed increasing sulfate reduction rates from near zero at the surface to a peak at 2–5 cm (up to 29 nmol cm23 d21)...

2010
Hilmar Hofmann Luisa Federwisch Frank Peeters

This study investigates the role of surface waves and the associated disturbance of littoral sediments for the release and later distribution of dissolved methane in lakes. Surface wave field, wave-induced currents, acoustic backscatter strength, and the concentration and distribution of dissolved methane were measured simultaneously in Lake Constance, Germany. The data indicate that surface wa...

Ghoochian, Mehrnaz , Sobhanardakani, Soheil , Taghavi, Lobat ,

Background and Purpose: The heavy metal pollution and its fractionations in the surface sediments of Darreh-Morad Beyg River, Hamedan City were monitored for Cd, Cr, Cu, Fe, Ni, Pb, and Zn in 2014.   Materials and Methods: Totally 30 surface sediment samples were taken from 10 stations with three replicates. The samples subjected to bulk digestion and chemical partitioning. The concentr...

Journal: :محیط شناسی 0
عبدالرضا کرباسی دانشکده محیط زیست دانشگاه تهران غلامرضا نبی بیدهندی دانشکده محیط زیست دانشگاه تهران فریدون غضبان دانشکده محیط زیست دانشگاه تهران شکوه کوکبی حبیب زاده کارشناس ارشد مهندسی محیط زیست دانشکدة محیط زیست دانشگاه تهران

in the recent years, sediments are used for the assessment of pollution. since sediments have been in contact for a long time with over lying water, therefore they have been able to adsorb pollution on to their surface. in the present investigation, the surficial sediments of siahrud river have been analyzed. the loose, sulphide and organic bonds of metals with various sedimentary phases has be...

2013
Kumar Manoj Balwant Kumar Pratap Kumar Padhy

The Subarnarekha River is one of the most important east flowing rivers of India. The river in West Bengal and Odisha is site for the Subarnarekha Barrage Project and Kirtania port respectively. The major objectives of the present study were to investigate the pre-projects level of heavy metals in water and sediments of the Subarnarekha River along the projects’ sites. Water and Surface sedimen...

2017
Stuart L. Simpson Brad M. Angel Dianne F. Jolley

The equilibration and bioavailability of metals in laboratory-contaminated sediments has been investigated in order to provide better guidance on acceptable procedures for spiking sediments with metals for use in the development whole-sediment toxicity tests. The equilibration rates of Cd, Cu, Ni and Zn spiked into three estuarine surface sediments with varying properties were investigated. Cha...

Journal: :The Science of the total environment 2013
F Mermillod-Blondin A Foulquier F Gilbert S Navel B Montuelle F Bellvert G Comte V Grossi F Fourel C Lecuyer L Simon

The interactions between invertebrates and micro-organisms living in streambed sediments often play key roles in the regulation of nutrient and organic matter fluxes in aquatic ecosystems. However, benthic sediments also constitute a privileged compartment for the accumulation of persistent organic pollutants such as PAHs or PCBs that may affect the diversity, abundance and activity of benthic ...

2011
Vineet Goswami Sunil K. Singh Ravi Bhushan Vinai K. Rai

[1] Sr and Nd isotopic composition of silicate fractions of sediments have been measured in two well dated gravity cores from the eastern Arabian Sea archiving a depositional history of ∼29 and ∼40 ka. The Sr/Sr and "Nd in the northern core (SS‐3104G; 12.8°N, 71.7°E) ranges from 0.71416 to 0.71840 and −8.8 to −12.8; these variations are limited compared to those in the southeastern core (SS‐310...

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