نتایج جستجو برای: sediment particles

تعداد نتایج: 191589  

2016
Douglas J. Jerolmack Meredith D Reitz Meredith D. Reitz

Grain size distributions in eolian settings are the result of both sorting and abrasion of grains by saltation. The two are tightly coupled because mobility of particles determines abrasion rate, while abrasion affects the mobility of particles by changing their mass and shape; few field studies have examined this quantitatively. We measured grain size and shape over a 9 km transect downwind of...

Journal: :Environmental science. Processes & impacts 2013
Qi Luo Paige Adams Junhe Lu Miguel Cabrera Qingguo Huang

This research studied the occurrence of estrogens in the Upper Satilla watershed, Georgia, USA, which was impacted by poultry litter land application and discharge from a sewage treatment plant (STP) receiving poultry wastes. Over 14 months, four estrogens in stream water, sediment, suspended particles, and STP samples were quantified by LC/MS. Estrogens were consistently found in the STP influ...

Journal: :Integrated environmental assessment and management 2008
Henrik Rye Mark Reed Tone Karin Frost Mathijs G D Smit Ismail Durgut Øistein Johansen May Kristin Ditlevsen

Drilling discharges are complex mixtures of chemical components and particles which might lead to toxic and nontoxic stress in the environment. In order to be able to evaluate the potential environmental consequences of such discharges in the water column and in sediments, a numerical model was developed. The model includes water column stratification, ocean currents and turbulence, natural bur...

Journal: :Heliyon 2023

Plastic debris is accumulating in all environments globally and South Africa’s poor waste management plan has led to an increase plastic contamination throughout the country. Information about microplastics (MPs) urban rural coastal Africa poor. The aim of this study was determine MP concentrations water (particles/L) sediment (particles/kg). Sampling took place summer 2020 during low tide at 1...

2014
Raúl López Javier Barragán

The relation between the equivalent roughness and different grain size percentiles of the sediment in gravel-bed rivers was determined under the hypothesis that the vertical distribution of the flow velocity follows a logarithmic law. A set of 954 data points was selected from rivers with gravel size sediment or larger, with a non-sinuous alignment and free of vegetation or obstacles. According...

ژورنال: آبخیزداری ایران 2021

The purpose of this study was investigating the effect of eleven gabion and five masonry dams on trapping eroded particles in the razin watershed located north of Kermanshah township. The frequency of sand particles increased by 40.67 percent and the percentage of gravel, silt and clay particles decreased by 14.37, 56.55 and 69.93 percent in sediments behind the gabion dams as compared to the w...

2016
Christian Wurzbacher Andrea Fuchs Katrin Attermeyer Katharina Frindte Hans-Peter Grossart Michael Hupfer Peter Casper Michael T. Monaghan

Sediments are depositional areas where particles sink from water columns, but they are also microbial hotspots that play an important role in biogeochemical cycles. Unfortunately, the importance of both processes in structuring microbial community composition has not been assessed. We surveyed all organismic signals of the last ca. 170 years of sediment by metabarcoding, identifying global tren...

2004
N. L. Rose J. F. Boyle Y. Du C. Yi X. Dai P. G. Appleby H. Bennion S. Cai L. Yu

As part of a study using lake sediments to determine the extent and causes of human impacts to lakes along an east–west transect following the Yangtse River, sediment cores were taken from Taihu in eastern China. Previous studies have focussed on the impacts of direct inputs of pollutants from municipal and industrial wastewater but little work has been undertaken on trends in atmospheric depos...

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...

2006
Tu

1.1 This guide covers procedures for measuring the bioac,cumulation of sediment-associatid contaminants by infaunal .invertebrates. Marine, estuarine, and freshwater sediments are a major sink for chemicals that sorb preferentially to particles, 'such as organic compounds with high octanol-waterpartitioning coefficients (KO,) (for example, polychlorinated ,biphenyls (PCBs) and dichlorodiphenylt...

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