نتایج جستجو برای: deep water sediments

تعداد نتایج: 764487  

Journal: :مرتع و آبخیزداری 0
محسن پادیاب دانشجوی دکتری آبخیزداری دانشکدة منابع طبیعی، دانشگاه تهران سادات فیض نیا استاد دانشکدة منابع طبیعی، دانشگاه تهران حسن احمدی استاد گروه آبخیزداری، دانشگاه آزاد اسلامی، واحد علوم و تحقیقات تهران اردشیر شفیعی عضو هیئت علمی مرکز تحقیقات کشاورزی و منابع طبیعی استان کهگیلویه و بویراحمد

evaluation of changes present in soil and water resources due to operation implement of floodwater spreading is necessary to assess their positive or negative resultant effect. rate of the internal sediment to diversion spreader channels, surface sedimentation and aggregation of the spreading field depth are most important effective attributes on the yield of floodwater spreading systems. these...

2016
S. Chamoun G. De Cesare

Reservoir sedimentation is a worldwide problem affecting sustainable storage use as well as sediment transport downstream of dams. Various techniques are applied for sediment mitigation, among which, venting of turbidity currents. This paper reviews, discusses and evaluates venting of turbidity currents based on an experimental approach. Data acquisition during the tests is accomplished using f...

2004
M. E. Torres B. M. A. Teichert A. M. Tréhu W. Borowski H. Tomaru

[1] Drilling in the Cascadia accretionary complex enable us to evaluate the contribution of dehydration reactions and gas hydrate dissociation to pore water freshening. The observed freshening with depth and distance from the prism toe is consistent with enhanced conversion of smectite to illite, driven by increase in temperature and age of accreted sediments. Although they contain gas hydrate ...

2016
Ignacio A. Rodriguez-Jorquera Cecilia Silva-Sanchez Mark Strynar Nancy D. Denslow Gurpal S. Toor Todd Miller

Current approaches to protect biodiversity by establishing protected areas usually gloss over water pollution as a threat. Our objective was to determine the longitudinal and seasonal distribution of perfluoroalkyl acids (PFAAs) in water column and sediments from a wastewater dominated stream that enters preservation areas. Water samples were collected along the longitudinal section (six sites,...

2014
Madeline D. Miller Jess F. Adkins David A. Hodell

Despite their potential to inform past ocean salinity, dO, and temperature, high-resolution depth profiles of interstitial water chloride concentration and hydrogen and oxygen isotopes exist in very few locations. One of the primary limitations to the recovery of these depth profiles is that traditional interstitial water sampling requires 5–10 cm whole rounds of the sediment core, which has th...

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 ...

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: :Applied and environmental microbiology 1995
T Hoaki M Nishijima H Miyashita T Maruyama

Microbial communities in marine hydrothermal sediments (0 to 30 cm deep) in an inlet of Kodakara-Jima Island, Kagoshima, Japan, were studied with reference to environmental factors, especially the presence of amino acids. The study area was shallow, and the sea floor was covered with sand through which hot volcanic gas bubbled and geothermally heated water seeped out. The total bacterial densit...

Journal: :Water research 2017
Alexis Grandcoin Stéphanie Piel Estelle Baurès

The widely occurring degradation product aminomethylphosphonic acid (AMPA) is a result of glyphosate and amino-polyphosphonate degradation. Massive use of the parent compounds leads to the ubiquity of AMPA in the environment, and particularly in water. The purpose of this review is to summarize and discuss current insights into AMPA formation, transport, persistence and toxicity. In agricultura...

Journal: :Applied and environmental microbiology 2009
Hongyue Dang Xiwu Luan Jingyi Zhao Jing Li

Diverse nifH and nifH-like gene sequences were obtained from the deep-sea surface sediments of the methane hydrate-bearing Okhotsk Sea. Some sequences formed novel families of the NifH or NifH-like proteins, of currently unresolved bacterial or archaeal origin. Comparison with other marine environments indicates environmental specificity of some of the sequences, either unique to the methane se...

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