نتایج جستجو برای: sediments

تعداد نتایج: 28437  

Journal: :FEMS microbiology ecology 2016
Yongqin Liu John C Priscu Jinbo Xiong Ralf Conrad Trista Vick-Majors Haiyan Chu Juzhi Hou

Archaeal communities and the factors regulating their diversity in high altitude lakes are poorly understood. Here, we provide the first high-throughput sequencing study of Archaea from Tibetan Plateau lake sediments. We analyzed twenty lake sediments from the world's highest and largest plateau and found diverse archaeal assemblages that clustered into groups dominated by methanogenic Euryarch...

2018
Maria Fajer Martyna Anna Rzetala

The geochemical characteristics of sediments deposited within a channel-type reservoir situated behind the weir of a water mill on the River Liswarta (southern Poland) were studied in relation to land use in the catchment. The catchment in question is an agricultural one with large forest areas. The contamination of sediments with trace elements was assessed using the geoaccumulation index. The...

Journal: :Environmental geochemistry and health 2004
H Wang C X Wang Z J Wang Z H Cao

The BCR (European Communities Bureau of Reference) three-step sequential extraction procedure was applied to fractionate heavy metals in the sediment of Taihu Lake. For the determination of total metal concentration of the sediments, sample digestion was achieved by using HF/H2O2/HNO3 (2/1/1) acid mixture in a microwave-irradiated closed vessel system. The concentrations of Cd, Ni, Cr, Zn, Cu a...

Journal: :Journal of water and health 2009
Sylvain Skraber Jack Schijven Ronald Italiaander Ana Maria de Roda Husman

Our study aimed to assess the accumulation of bacteriophages in sandy and clayey fresh water sediments. All of the 24 natural fresh water sediments were positive for somatic and F-specific phages, though their concentrations in the overlying water were undetectable in 1 and 11 samples, respectively, out of 24, corresponding to 4 and 46% for somatic and F-specific phages, respectively. Based on ...

2012
A. Baran M. Tarnawski

Deposition of sediments on land in atmospheric conditions causes many risks connected with environmental protection. Particularly dangerous is leaching of heavy metals from sediments deposited on land The research aimed at assessment of leaching of heavy metals from dredged bottom sediments potentially disposed on land. In this research it has been shown that the leaching of heavy metals during...

2016
Lauren E. Kinsman-Costello Stephen K. Hamilton Jay T. Lennon

Phosphorus (P) retention is an important ecosystem service provided by sediments and soils. However, when shallow aquatic sediments and poorly drained soils dry and re-flood, they can be a source, rather than a sink, of P. Using experimental drying and re-flooding in the laboratory, we assessed the resultant sediment–water P exchange in a biogeochemically diverse set of sediments from 16 sites ...

2009
C. Soares P. Sobral

Bioturbation can modify the biogeochemical properties of cohesive sediments and affect sediment stability. Here, we investigate the effects of the clam, Scrobicularia plana, on the erodibility of estuarine sediments. Muddy sediments with different mud contents were collected with minimal disturbance at Ponta da Erva, Hortas and Samouco in the Tagus Estuary. S. plana 40.7±0.3 mm length, (mean ± ...

2010
Qingren Wang Yuncong Li

Purpose The aim of this study was to assess phosphorusretention (Pret) capacities via P adsorption (Pads) and desorption (Pdes) by sediments collected from six different sources associated with various origins, physical, and chemical characteristics. Materials and methods Sediment samples were collected in the State of Florida, the USA, from estuary, marine, wetland, canal, river, and lake, res...

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...

Journal: :Environmental pollution 2009
Xiuling Bai Shiming Ding Chengxin Fan Tao Liu Dan Shi Lu Zhang

Organic phosphorus (P) fractions in surface sediments from a large shallow, eutrophic Lake Taihu, China, were extracted with 0.1 M NaOH after pre-treatment of the sediments with a solution composed of 0.1 M EDTA and 2% (w/v) Na(2)S(2)O(4). Composition of organic P in the extracts was then characterized by (31)P nuclear magnetic resonance spectroscopy ((31)P NMR). Several P species, including ph...

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