Results 1 - 10 of 496
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[en] The information available suggests that the concentration of total suspended particulate matter in major urban areas are reaching unprecended levels(>230μg/m3). From the first documented study on total suspended particulate matter in 1977, a review of the various studies both in Nairobi and Mombasa is made with a view to bring to light, the assessment of air pollution in Kenya. (author)0
[en] We present in this study the hydrodynamic regimes analysis in an electroflotation column in batch mode. The study shows the effects of physicochemical liquid phase properties and current density on Reynolds number. The method of video recording and image processing was used to determine the diameter, the rise velocity of bubble and the gas retention within three model solutions. Modelling Reynolds number by nonlinear regression method has been used in order to predict optimal treatment regime of an industrial effluent. The control parameter is the suspended solids purification rate. This rate exceeded 95 pour cent in optimal regime of effluent treatment.
[en] The present paper investigates the effect of vertical magnetic field and dust particles on the stability of a micropolar fluid layer heated and soluted from below. The Lorentz force term is introduced due to the presence of a magnetic field, which gives rise to oscillatory motions in the system. The other reason for the introduction of overstable motions is the coupling between micropolar and thermosolutal effects. The normal mode technique, along with the Boussinesq approximation is used to derive the dispersion relation. The thermal Rayleigh number is found for both types of convections and it is observed that it is more for stationary motions than for oscillatory motions; except for high values of the suspended particles factor. The effect of solute Rayleigh number and Chandrasekhar number is to stabilize the micropolar fluid layer while dust particles hasten the onset of convection. Interestingly, as the suspended particle factor increases, the mode of instability shifts from overstability to stationary convection. The effect of micropolar coefficient of coupling is found to stabilize the fluid-particle layer for stationary convection. Some earlier known results are recovered as special cases from the present formulation. (author)
[en] This document comprises the Operational Test Report for the 241-AZ-101 Suspended Solids Profiler. This document presents the results of Operational Testing of the 241-AZ-101 Suspended Solids Profiler (SSP). Testing of the SSP was performed in accordance with OTP-260-005, ''SUSPENDED SOLIDS PROFILER OPERATIONAL TEST PROCEDURE''. The objective of the testing was to verify that all equipment and components functioned as designed, following construction completion and turnover to operations
[en] Highlights: • Reverse ignition reduced the emissions of the unburned gases in the studied stove. • Reverse ignition considerably reduced the emissions of Organic Carbon. • Reverse ignition increased the pyrolysis, and then the emissions of Elemental Carbon. • The Carbon and Oxygen mass fraction of the particles were linked to the temperature. - Abstract: A comparison of the effects of traditional stove ignition with paper under the wood versus the Top-Down ignition of a wood crib is made, comparing the gaseous and particulate emissions. Top-Down ignition reduced the unburnt gas emissions by a factor of 2. The Total Suspended Particle (TSP) emission was reduced by about 1/3, while Organic Carbon (OC) was reduced by 73% relative to traditional under-fire ignition. Never the less the Elemental Carbon (EC) doubled in Top-Down ignition. The particle formation mechanism is also different with primary emissions being nanoparticles (20 nm - 50 nm) which agglomerated as they passed along the flue duct. The TSP were generally composed of CHO while the smaller size range 1 and especially the PM0.1 contained other elements.
[en] Observations of salinity, temperature, suspended sediment concentration (SSC) and tidal current velocity were made in the lower and along the longitudinal axis of Sungai Selangor estuary over neap-spring cycles. The variations of these parameters at the measurement stations and along the channel are presented to illustrate the water and sediment dynamics in the estuary. The results shows that the Sungai Selangor estuary changes from a partially-mixed type during neaps to a well-mixed one during springs, promoted by stronger tidal energy during the higher tidal ranges. The strong neap density stratification is also promoted by the high river discharges during the measurement period. Maximum concentration of suspended sediment (> 2000 mg/l) occurs during maximum current velocities both during flood and ebb. The maximum salinity was achieved during high water slack but the salt water was totally flushed out of estuary during low water springs. The longitudinal axis measurement indicates that a partially-developed zone of turbidity maximum with a sediment concentration over 1000 mg/l was observed at the limit of salt water intrusion in salinity range less than 1 ppt. Tidal pumping as oppose to the estuarine circulation is the more dominant factor in the maximum formation as the salt water is totally excluded at low water. (Author)
[en] In this study, the concentrations of ambient total suspended particulates (TSP) and their dry deposition were measured using a PS-1 sampler with dry deposition plates at a wetland sampling site in central Taiwan during a sampling period from October 2016 to December 2016. The PS-1 sampler was fixed at set distances (1.5 and 2 m) from a dry deposition plate, and sampled particulate pollutants were sampled to determine their concentrations and dry deposition rates simultaneously. A dry deposition plate 3 m from the PS-1 sampler was also used to collect dry deposition particulate. This plate was also used to compare dry depositions from ambient air, collected from new device. The results thus obtained indicated that the average dry deposition rates on the dry deposition plates that were 1.5 and 2 m from the sampler were 103.15 and 103.94 µg/m2 min, respectively, in October, 83.36 and 100.18 µg/m2 min in November, and 171.2 and 157.5 µg/m2 min in December. These dry deposition rates were compared with that 3 m away from the PS-1 sampler. The statistical t test revealed no significant differences between the dry depositions on dry deposition plates at 1.5 and 2 m from the sampler. The dry deposition rates at 1.5 and 2 m from the sampler did not differ significantly from that at 3 m from the PS-1 sampler. This study proves that a PS-1 sampler can be combined with a dry deposition plate to measure TSP concentrations and dry depositions simultaneously using a single device.
[en] Forested catchments are an important part of the mercury (Hg) cycle and a link between the atmospheric and the aquatic environments. In this study, Hg input and output fluxes and its retention were investigated at subtropical forested catchments in southwest China. Significantly enhanced atmospheric Hg inputs were observed, and the contribution of litterfall Hg plays a more important role at these subtropical forested catchments. The ratios of Hg output fluxes from stream water to total input were 2.5% and 1.2% for LGS and TSP, which were markedly lower than those reported from Europe and North America. The current annual input Hg only accounted for 0.8 and 1.8 per mille to the Hg stored in the upper 90 cm of soil in LGS and TSP. These suggest that subtropical forested catchments are important for retention of atmospheric mercury deposition in southwest China. - The subtropical forested catchments are important for retention of atmospheric mercury deposition in southwest China
[en] Meteorological parameters wind speed, temperature, humidity and stability play a very important role in the transport and dispersion of particulate matter affecting the concentration of Total Suspended Particulate Matter (TSPM). These parameters vary from place to place, month to month and also during day and night. In addition coastal atmospheric conditions widely vary compared to inland site due to land sea interface. This paper presents the results of correlation between various meteorological parameters and TSPM at Kalpakkam (12° 33inch N, 80°11inch E) on the east coast, about 75 km south of Chennai, India