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At least 1,099 records · Page 61Linked to original sources
PubMed2003

Numerical modeling method on the movement of water flow and suspended solids in two-dimensional sedimentation tanks in the wastewater treatment plant.

Taking the distributing calculation of velocity and concentration as an example, the paper established a series of governing equations by the vorticity-stream function method, and dispersed the equations by the finite differencing method. After figuring out the distribution field of velocity, the paper also calculated the concentration distribution in sedimentation tank by using the two-dimensional concentration transport equation. The validity and feasibility of the numerical method was verified through comparing with experimental data. Furthermore, the paper carried out a tentative exploration into the application of numerical simulation of sedimentation tanks.

Geologic Sediments↗
PubMed2003

Effect of environmental conditions on the erosional resistance of cohesive sediment deposits in sewers.

The potential to adjust sewer network operation in order to control the level of transported sediment in sewage so as to enhance the performance of end-of-pipe treatment works is now being investigated. However for this to become a practical management option there is a need to be able to understand the processes which control the movement of sediments that are found in many combined sewers. Crucial to this understanding is an ability to predict how sediments from in-sewer deposits, are released by the action of vigorous flows. This paper reports on a laboratory investigation that aimed to investigate the effect that the environmental conditions during deposit formation can have on the ability of fine-grained organic sediment within in-sewer deposits to resist erosion and subsequent release into transport.

Forecasting↗
PubMed2004

[Distributed modeling of nutrient transport in basin with support of remote sensing and geography information system].

Agricultural non-point source pollution has become serious in our country. Modeling the processes of nutrient(especially nitrogen and phosphorus) transport in basin and evaluating the adopted management practices are important for controlling the impact of non-point pollution on environment. A research scheme for distributed simulation of nutrient transport processes in Lianshui Basin, Xingguo County, Jiangxi Province was designed, with the support of remote sensing (RS) and geography information system (GIS). The research procedure included model selection, discretization and spatial parameterization of the basin, prediction, and validation. SWAT model was selected, and basin-subbasin-hydrological response unit discretization scheme was designed. Supported by RS and GIS and based on the topographic features of the watershed, the subwatershed discretization divided the watershed into subbasins, and each subbasin could be further partitioned into multiple hydrologic response units (HRUs), which were unique soil/land use combinations within the subbasin and modeled through statistical spatial overlay analysis. The parameters of land use were obtained from the supervised classification of TM imagery based on field training samples, and those of soil were obtained from field sampling and further interpolated through geostatistical method. The simulation was carried out by using the data from 1991 to 2000. The results showed that the simulation accuracy of annual runoff water yield and sediment yield was 89.9% and 70.2%, respectively.

Computer Simulation↗
PubMed2004

[Adsorption of cation-nonionic mixed surfactants onto sediment and their effects on adsorption of nitrobenzene from water].

Adsorption behaviors of nitrobenzene, a nonionic surfactant (Triton X-100), a cation surfactant (CPC) and their mixture onto a sediment were investigated. The adsorption of Triton X-100 onto the sediment is enhanced with increasing of co-existed CPC at relatively low concentrations but decreased at relatively high concentrations. The adsorption of CPC onto the sediment decreased a little with increasing of co-existed Triton X-100. In natural waters, cation surfactants and nonionic surfactants will be largely adsorbed by soils or sediments. The adsorption of nitrobenzene onto sediment is linear and enhanced by the co-existed Triton X-100 or CPC, and will be significantly enhanced by the mixture of CPC-Triton X-100. Therefore, cation-nonionic mixed surfactants are potentially used to enhance adsorption of organic contaminants onto soils or sediments and to prepare organobentonite for improving their performance in wastewater treatment.

Adsorption↗
PubMed2005

[Response of sediment production to land-use change in Luergou watershed of Loess Plateau].

The study on the effects of different land use patterns on the sediment production in Luergou watershed of Loess Plateau indicated that in comparing with 1982, the areas of forest and grass and of terrace in 1989 increased by 5% and 2.09%, respectively, while that of slope plowland decreased by 1.5%, with the area of naked land and shrubbery respectively increased and decreased a little. During 1998 - 2000, with the increase of vegetation cover and the decrease of steep slope plowland, the sediment production reduced significantly under high precipitation, 85326 and 52937 t under the precipitation of 803 and 786 mm, respectively, and not distinguishable in dry years. The reduction effect had a strong seasonality, which consisted with rainfall distribution. For example, in a month with 50 mm precipitation, the mean daily sediment concentration was reduced by 6 kg x m(-3), while in a month with 100 mm precipitation, the reduction was 12 kg x m(-3). Rainfall intensity also played an important role in soil erosion and sediment production, regardless of land use conditions.

Conservation of Natural Resources↗
PubMed2004

Efficient and rapid method for extraction of intact phospholipids from sediments combined with molecular structure elucidation using LC-ESI-MS-MS analysis.

This paper presents the application of an efficient method for extraction and fractionation of intact phospholipids (PLs) from complex sediment matrices and elucidation of their molecular structure by normal-phase HPLC-ESI-MS-MS. Flow-blending extraction was tested with different solvent mixtures and the best recovery of all PLs classes from the sediment matrix was achieved by using methanol-dichloromethane-buffer, 2:1:0.8. The applied LC-ESI-MS system has linearity of R2=0.98 and a detection limit of 0.5 ng/PL, sufficient for reliable identification of complex mixtures of PLs. MS-MS analyses using a triple-quadrupole mass spectrometer enables detection of individual PL side-chain composition and, hence, characterization of the living organisms contributing to the sedimentary organic material. Parallel GC-MS analysis of the hydrolysed phospholipid fatty acids supports the characterized fatty acid patterns determined from intact PLs. The PL inventory of different investigated lacustrine surface sediments shows predominantly high abundance of phosphatidylglycerols and phosphatidylethanolamines and phosphatidyl-mono- and dimethyl-ethanolamines with fatty acyl side-chains typically known from bacteria. In a sample from Lake Baikal intense signals of bacterial 14:0-acyl-PGs were also identified, for the first time in sediments as far as we are aware.

Bacteria↗
PubMed2003

Trace metal concentrations in sediments and oysters of Botany Bay, NSW, Australia.

Surfical sediment (< 63 microm) trace metal concentrations (Zn, Cu, Pd, Cd, As) were analyzed from seven sites in Botany Bay, NSW, Australia, to assess the extent of contamination from the surrounding urban areas. The northwest shoreline of Botany Bay contained high surfical sediment trace metal concentrations relative to the southern shoreline. Surfical sediment Pb concentrations (10-120 microg/g) were above the current ANZECC/ARMCANZ interim sediment guideline value (50 microg/g) for the protection of benthic ecosystems at the northwest sites. Cooks River was identified as a major source of trace metals. Oysters grown in Botany Bay have greater Zn, Cu, and Cd concentrations than two relatively pristine reference locations, Jervis Bay and Batemans Bay, indicating that the Botany Bay region has elevated biologically available metal concentrations. Oyster tissue trace metal concentrations were below the Australian and New Zealand Food Authority standards. Translocation of oysters to sites around the bay identified Pb and Cd as the only trace metals to be accumulated over 3 months. Copper concentrations in transplanted oysters declined at most sites, indicating that the sites investigated in this study have less bioavailable copper than Woolooware Bay, the source of the oysters. The shallow waters along the southern shoreline are protected from the tidal flow that carry contaminated sediments and the biologically available trace metals appear to be low.

Animals↗