Faecal coliform attachment to settleable suspended sediments in fresh surface waters: linear partition model validation and sediment concentration effects

2015 ◽  
Vol 15 (4) ◽  
pp. 864-870 ◽  
Author(s):  
L. Jiang ◽  
Y. C. Chen ◽  
D. J. Zhu ◽  
Z. W. Liu
Keyword(s):  
Partition Coefficient ◽  
Surface Waters ◽  
Particle Surface ◽  
Suspended Sediments ◽  
Sediment Concentration ◽  
Faecal Coliform ◽  
Concentration Effects ◽  
Partition Model ◽  
Linear Partition ◽  
The Impact

Controlled experiments were conducted to examine the validity of the linear partition model for faecal coliform (FC) attachment to suspended sediments and assess the impact of sediment concentration on the attachment. Sediments were collected from a river in Beijing, China and the suspended particles <62 μm were separated out and mixed with FC suspensions. The experimental mass specific concentration of attached FC linearly increased with the free-floating FC concentration, with the partition coefficient for four different sediment concentrations ranging from 0.2286 to 0.2695 L/g. Actually, the results can be well described using a single partition coefficient of 0.2565 L/g. The rate of sediment particle surface covered by attached FC was in the range of 0.32 × 10−5–0.58 × 10−5, and the relatively low rate gave a possible explanation of the linear relationship. The experimental fraction of attached FC significantly increased with increasing sediment concentration, ranging from 7.5 to 54.2%, and this was well explained by the linear partition model. These results proved that the linear partition model was valid in describing FC attachment to suspended sediments in surface waters and the attached fraction was sediment concentration dependent, while the impact of suspended sediment concentration on the partition coefficient was insignificant.

scholarly journals Getting information on suspended sediments in a large river from acoustic backscatter

2018 ◽  
Vol 40 ◽  
pp. 04017
Author(s):  
Adrien Vergne ◽  
Céline Berni ◽  
Jérôme Le Coz
Keyword(s):  
Suspended Sediment Concentration ◽  
Spatial Information ◽  
Suspended Sediments ◽  
Sediment Concentration ◽  
Large River ◽  
Acoustic Backscatter ◽  
Qualitative Information ◽  
Sediment Size ◽  
The Common

There has been a growing interest in the last decade in extracting information on Suspended Sediment Concentration (SSC) from acoustic backscatter in rivers. Quantitative techniques are not yet effective, but acoustic backscatter already provides qualitative information on suspended sediments. In particular, in the common case of a bi-modal sediment size distribution, corrected acoustic backscatter can be used to look for sand particles in suspension and provide spatial information on their distribution throughout a river crosssection. This paper presents a case-study where these techniques have been applied.

The impact of nitrogen deposition on upland surface waters in Great Britain: A regional assessment of nitrate leaching

1995 ◽  
Vol 85 (2) ◽  
pp. 297-302 ◽  
Author(s):  
T. E. H. Allott ◽  
C. J. Curtis ◽  
J. Hall ◽  
R. Harriman ◽  
R. W. Battarbee
Keyword(s):  
Great Britain ◽  
Nitrogen Deposition ◽  
Surface Waters ◽  
Nitrate Leaching ◽  
Regional Assessment ◽  
The Impact

Fouling on a Multistage Axial Compressor in the Presence of a Third Substance at the Particle/Surface Interface

2018 ◽  
Author(s):  
Nicola Aldi ◽  
Nicola Casari ◽  
Devid Dainese ◽  
Mirko Morini ◽  
Michele Pinelli ◽  
...  
Keyword(s):  
Impact Velocity ◽  
Gas Turbines ◽  
Particle Deposition ◽  
Fluid Dynamic ◽  
Particle Surface ◽  
Axial Compressor ◽  
Micro Particles ◽  
Multistage Compressor ◽  
Particle Ingestion ◽  
The Impact

Solid particle ingestion is one of the principal degradation mechanisms in the compressor and turbine sections of gas turbines. In particular, in industrial applications, the micro-particles not captured by the air filtration system can cause deposits on blades and, consequently, can result in a decrease in compressor performance. It is of great interest to the industry to determine which zones of the compressor blades are impacted by these small particles. However, this information often refers to single stage analysis. This paper presents three-dimensional numerical simulations of the micro-particle ingestion (0.15 μm – 1.50 μm) in a multistage (i.e. eight stage) subsonic axial compressor, carried out by means of a commercial CFD code. Particle trajectory simulations use a stochastic Lagrangian tracking method that solves the equations of motion separately from the continuous phase. The effects of humidity, or more generally, the effects of a third substance at the particle/surface interface (which is considered one of the major promoters of fouling) is then studied. The behavior of wet and oiled particles, in addition to the usual dry particles, is taken into consideration. In the dry case, the particle deposition is established only by using the sticking probability. This quantity links the kinematic characteristics of particle impact on the blade with the fouling phenomenon. In the other two cases, the effect of the presence of a third substance at the particle/surface interface is considered by means of an energy-based model. Moreover, the influence of the tangential impact velocity on particle deposition is analyzed. Introducing the effect of a third substance, such as humidity or oil, the phenomenon of fouling concerns the same areas of the multistage compressor. The most significant results are obtained by combining the effect of the third substance with the effect of the tangential component of the impact velocity of the particles. The deposition trends obtained with these conditions are comparable with those reported in literature, highlighting how the deposits are mainly concentrated in the early stages of a multistage compressor. Particular fluid dynamic phenomena, such as corner separations and clearance vortices, strongly influence the location of particle deposits.

scholarly journals Estimation of Impact From Surface Runoff on Water Objects in Urban Landscape Conditions

2019 ◽  
Keyword(s):  
Urban Environment ◽  
Surface Waters ◽  
Surface Runoff ◽  
System Analysis ◽  
Urban Landscape ◽  
Salt Content ◽  
Atmospheric Precipitation ◽  
Quality Of Water ◽  
The Impact

The quality of surface water remains an important issue today. This is particularly acute for water bodies located in the urban-basin geosystems. Purpose. To estimate pressure of atmospheric precipitation within the urban landscape basin geosystem on the river water (by example of the Kharkiv river). Methods. Field landscaping, ecological, landscape-geochemical; analytical; system analysis; chemical analytical; statistical Results. An assessment of the state of surface waters under the impact from the surface runoff of atmospheric origin during 2014-2016, and partly from 2017-2019, formed under the influence of the transport (partly residential) subsystem of the urban area and surface waters in Kharkiv. On the salt content, the characteristic of water quality is "moderately polluted" (1,6); on the tropho-saprobiological indicators, the quality of water is characterized as "polluted" (from 3.1 to 2.75 along the river). It is in this context the impact of waters, which is formed in the conditions of the urban environment for the quality of natural waters, is well demonstrated. The presence of high values of pollutants and natural factors. The assessment of the quality of water on the content of specific indicators is "moderately polluted" (from 2.28 to 1.85). Conclusions. The water of the Kharkiv region, which has a strong influence from the urban environment, has a grade III quality; the water is "moderately polluted". Environmental assessment indicates the impact of surface runoff already on the middle part of the river, which increases in accordance with the conditions of the operation of urban landscapes and anthropogenic (transport) load.

scholarly journals Introduction to the project DUNE, a DUst experiment in a low Nutrient, low chlorophyll Ecosystem

2013 ◽  
Vol 10 (7) ◽  
pp. 12491-12527 ◽  
Author(s):  
C. Guieu ◽  
F. Dulac ◽  
C. Ridame ◽  
P. Pondaven
Keyword(s):  
Trace Elements ◽  
Atmospheric Deposition ◽  
Mediterranean Sea ◽  
Surface Waters ◽  
Carbon Pump ◽  
Mesocosm Experiments ◽  
The Mediterranean ◽  
Atmospheric Inputs ◽  
Oligotrophic Ecosystem ◽  
The Impact

Abstract. The main goal of the project DUNE was to estimate the impact of atmospheric deposition on an oligotrophic ecosystem based on mesocosm experiments simulating strong atmospheric inputs of Aeolian dust. Atmospheric deposition is now recognized as a significant source of macro- and micro-nutrients for the surface ocean, but the quantification of its role on the biological carbon pump is still poorly determined. We proposed in DUNE to investigate the role of atmospheric inputs on the functioning of an oligotrophic system particularly well adapted to this kind of study: the Mediterranean Sea. The Mediterranean Sea – etymologically, sea surrounded by land – is submitted to atmospheric inputs that are very variable both in frequency and intensity. During the thermal stratification period, only atmospheric deposition is prone to fertilize Mediterranean surface waters which has become very oligotrophic due to the nutrient depletion (after the spring bloom). This paper describes the objectives of DUNE and the implementation plan of a series of mesocosms experiments during which either wet or dry and a succession of two wet deposition fluxes of 10 g m−2 of Saharan dust have been simulated. After the presentation of the main biogeochemical initial conditions of the site at the time of each experiment, a general overview of the papers published in this special issue is presented, including laboratory results on the solubility of trace elements in erodible soils in addition to results from the mesocosm experiments. Our mesocosm experiments aimed at being representative of real atmospheric deposition events onto the surface of oligotrophic marine waters and were an original attempt to consider the vertical dimension in the study of the fate of atmospheric deposition within surface waters. Results obtained can be more easily extrapolated to quantify budgets and parameterize processes such as particle migration through a "captured water column". The strong simulated dust deposition events were found to impact the dissolved concentrations of inorganic dissolved phosphorus, nitrogen, iron and other trace elements. In the case of Fe, adsorption on sinking particles yields a decrease in dissolved concentration unless binding ligands were produced following a former deposition input and associated fertilization. For the first time, a quantification of the C export induced by the aerosol addition was possible. Description and parameterization of biotic (heterotrophs and autotrophs, including diazotrophs) and abiotic processes (ballast effect due to lithogenic particles) after dust addition in sea surface water, result in a net particulate organic carbon export in part controlled by the "lithogenic carbon pump".

scholarly journals Curvas-chave de descargas de sedimentos em suspensão no Baixo São Francisco

2020 ◽  
Vol 13 (3) ◽  
pp. 1248 ◽  
Author(s):  
Solange Cavalcanti de Melo ◽  
José Coelho de Araújo Filho ◽  
Renata Maria Caminha Mendes de Oliveira Carvalho
Keyword(s):  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Suspended Sediments ◽  
Sediment Concentration ◽  
Gradual Reduction ◽  
Sao Francisco River ◽  
Sediment Loads ◽  
São Francisco River ◽  
Historical Series ◽  
Suspended Sediment Concentrations

RESUMOO conhecimento da análise quantitativa das concentrações de sedimentos em suspensão transportados pelo rio São Francisco bem como sua relação com as vazões é de muita importância, pois pode auxiliar na identificação dos efeitos da intervenção humana e ou ocasionados pelas condições naturais da região. As regiões a jusante dos barramentos no rio São Francisco apresentam como principal consequência a regularização das vazões e a diminuição das concentrações de sedimentos. O objetivo da pesquisa foi determinar as curvas-chave de sedimentos em suspensão (CCS) nas estações fluviométricas instaladas no Baixo São Francisco (BSF) após a barragem de Xingó. Para o estabelecimento dessas curvas foram utilizados dados de vazão e concentração de sedimentos em suspensão, obtidos do sistema Hidroweb no site da Agência Nacional da Água (ANA) no período de 1999 a 2018. Foram obtidas CCS para todo o trecho do BSF as quais apresentaram bons coeficientes de determinação. Na análise dos dados também foi possível perceber que nos últimos anos, desde 2013 houve redução gradativa das vazões disponibilizadas na barragem de Xingó. Consequentemente, houve também a redução gradativa das cargas de sedimentos em suspensão geradas nas estações de Piranhas, Traipu e Propriá, ou seja, os menores valores já registrados no BSF correspondendo as menores séries históricas tanto de vazão como de sedimentos em suspensão.  Keys curves of sediment discharges in suspension in the Lower São Francisco A B S T R A C TThe knowledge of the quantitative analysis of suspended sediment concentrations carried by the São Francisco River as well as its relation with the flows is of great importance, since it can help in the identification of the effects of human intervention and/or caused by the natural conditions of the region. In the downstream regions of the São Francisco riverbanks, the main consequence was the regularization of flow rates and the reduction of sediment concentrations. The objective of the research was to determine the key curves of suspended sediments (CCS) at the fluviometric stations installed in the lower São Francisco river after Xingó dam. For the evaluation, flow data and suspended sediment concentration were used. These data were obtained from the Hidroweb system on the website of the National Water Agency (ANA) from 1999 to 2018. CCS were plotted for all stretches and presented good coefficients of determination (R2). Based on the analysis of the data it was also possible to notice that in recent years, since 2013 there has been a gradual reduction of the flows available in the Xingó dam. Consequently, there was also a gradual reduction of suspended sediment loads generated at the Piranhas, Traipu and Propriá stations, that is, the lowest values already recorded in lower São Francisco, corresponding to the lower historical series of both discharge and suspended sediments.Keywords: dam, flow, sediments 

scholarly journals Stream plant chemistry as indicator of acid sulphate soils in Sweden

2008 ◽  
Vol 14 (1) ◽  
pp. 83 ◽  
Author(s):  
K. LAX
Keyword(s):  
Surface Waters ◽  
Stream Water ◽  
Low Ph ◽  
Fontinalis Antipyretica ◽  
Acid Sulphate ◽  
Fine Grained ◽  
Acid Sulphate Soils ◽  
Trace Element Chemistry ◽  
Study Results ◽  
The Impact

Results from the biogeochemical mapping (roots of aquatic plants and Fontinalis antipyretica) conducted by the Geological Survey of Sweden (SGU) reflects the metal load of surface waters draining acid sulphate (AS) soils in Sweden. In this study, results from the biogeochemical, soil geochemical and Quaternary mapping programmes at SGU were used to investigate the impact of fine-grained deposits hosting AS soils on stream water trace element chemistry in two separate areas. In the area around Lake Mälaren, postglacial sediments contain the highest levels of most trace elements studied. Owing to the low pH of AS soils and subsequent leaching, levels of nickel (Ni), cobalt (Co), copper (Cu), sulphur (S), yttrium (Y), uranium (U), tungsten (W), and molybdenum (Mo) were significantly elevated in aquatic roots. Levels were lower in the Skellefteå area, which may be explained by lower concentrations in source deposits. Concentrations of arsenic (As) and lead (Pb) were normal or impoverished in biogeochemical samples from postglacial, finegrained sediment areas. Maps based on ratios (Ni:Pb or Y:Pb) in biogeochemical samples can, together with results from Quaternary mapping, be used to predict areas with AS soils in Sweden.;

scholarly journals Agricultural Producers’ Awareness about the Impact of Fertilizers Overuse on the Environment

2019 ◽  
Vol 19 (4) ◽  
pp. 309
Author(s):  
Biljana Panin ◽  
Snežana Štrbac ◽  
Mira Pucarević ◽  
Nataša Stojić ◽  
Nataša Žugić Drakulić ◽  
...  
Keyword(s):  
Surface Waters ◽  
Organic Fertilizers ◽  
Farming Practices ◽  
Chemical Fertilizers ◽  
Agricultural Producers ◽  
Pollution Effects ◽  
Face To Face ◽  
The Impact ◽  
Harmful Effects ◽  
Nitrates Directive

Overuse of fertilizers can have harmful effects on the environment. The Nitrates Directive aims to protect water quality by preventing nitrates from agricultural sources polluting ground and surface waters and by promoting the use of good farming practices. The paper is based on research about agricultural producers’ awareness about the impact of fertilizers overuse on the environment. Data were collected by face to face interviews with farm owners on 39 farms in Serbia. Analysis of the collected data showed that all farmers use fertilizers. It is important to notice that 79.4% of farmers use chemical fertilizers more than recommended, and 87.1% use organic fertilizers more than recommended. Furthermore, 66.6% of farmers do not know specific harmful pollution effects of nitrates on soil and water. 71.7% of farmers have not heard about the Nitrates Directive. Therefore, it can be concluded that farmers are not sufficiently aware of fertilizers impact on the environment and it is necessary to provide education on this.

scholarly journals Characterizing and modelling the trapping efficiency of sedimentation basins downstream of harvested peat bog

2018 ◽  
Vol 45 (6) ◽  
pp. 478-488 ◽  
Author(s):  
Myriam Samson-Dô ◽  
André St-Hilaire
Keyword(s):  
Suspended Sediment Concentration ◽  
Suspended Sediments ◽  
Sediment Concentration ◽  
Drainage Water ◽  
Organic Content ◽  
Trapping Efficiency ◽  
Peat Moss ◽  
Decomposition Level ◽  
In Series ◽  
Sedimentation Basins

Peat moss harvesting is an important industry in Canada. To harvest peat, the water table of the peatland must be lowered to allow the surficial peat layer to dry and be harvested. Drainage water can contain suspended sediments, so at most harvesting sites, the water is routed through sedimentation basins. This work focuses on characterizing and modelling their trapping efficiency. Eight basins with different volume/watershed area ratios (705 to 4170 m3/km2) were studied in three Quebec regions. Suspended sediment concentration and discharge were monitored up- and downstream of each basin during the ice-free season. Basins with high ratios of volume/drainage area, multiple basin configurations (i.e., two basins in series or in parallel), and those equipped with a flow regulation structure were more efficient than regular basins. Moreover, the nature of sediments (size, decomposition level, and organic content) influences loads, but not the trapping efficiency. Finally, two empirical models developed to predict trapping efficiency of municipal sedimentation basins were tested and adapted for basins that capture peat sediments.

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