Xem 1-20 trên 22 kết quả Dissolved organic
  • This study was performed to develop software sensorsto predict the BOD5 of river water and wastewater. The software sensors were based on the multiple-regression analysis using the dissolved organic carbon(DOC) concentration, UV light absorbance at 254nm and synchronous fluorescence spectra. River water samples and wastewater treatment plant (WWTP)effluents were collected at 1-hour interval to evaluatethe feasibility of the software sensors.

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  • Water pollution is a major global problem that requires ongoing evaluation and revision of water resource policy at all levels (from international down to individual aquifers and wells). It has been suggested that it is the leading worldwide cause of deaths and diseases, and that it accounts for the deaths of more than 14,000 people daily.

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  • Effective prediction of transport of chemical pollutants through a subsurface groundwater system and associated assessments of risk requires a valid “conceptual model” of the contaminant migration scenario. The classical contaminant conceptual model is one of a near- surface “leachable source zone” where chemical contaminant is leached, i.e. dissolved/solubilised, into water infiltrating through the source (Figure 4.2).

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  • Remedial strategies for petroleum UST sites that include a combination of active source zone treatment with enhanced natural attenuation outside the contaminant plume core may consider chemical oxidation technologies. Many chemical oxidation techniques also provide residual dissolved oxygen that is used by aerobic microorganisms to biodegrade contaminants. In addition, these technologies may also oxidize reduced electron acceptors (e.g., nitrogen to nitrate, sulfides to sulfate), which are then used by anaerobic microorganisms to biodegrade contaminants.

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  • There exists a range of solutions to reduce exposure to indoor air pollution. This includes reducing the source of pollution and altering the living environment and user behavior. Source reduction involves improved cooking devices (with or without flue attached), cleaner fuel, and reduced need for fire. Alterations to the living environment include improved ventilation and improved kitchen design and stove placement. Altered user behavior includes fuel drying, stove and chimney maintenance, use of pot lids to conserve heat, and keeping children away from the smoke (Bruce et al.

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  • Natural groundwater quality changes start in the soil, where infiltrating rainfall dissolves carbon dioxide from biological activity in the soil to produce weak carbonic acid that may assist removal of soluble minerals from the underlying rocks, e.g. calcite cements. At the same time, soil organisms consume some of the oxygen that was dissolved in the rainfall. In temperate and humid climates with significant recharge, groundwater moves relatively quickly through the aquifer.

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  • Advection is the transport of dissolved solute mass present in groundwater due to the bulk flow (movement) of that groundwater. Advection alone (with no dispersion or reactive processes occurring) would cause a non-reactive solute to advect (move) at the mean groundwater pore velocity. All solutes undergo advection, however, reactive solutes are subject to influences by other processes detailed below. Molecular diffusion is the movement of solute ions in the direction of the con- centration gradient from high towards low concentrations. It effects all solutes.

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  • NATO is a political and military alliance that has been a suc- cessful example of an international structure, able to demon- strate both national and institutional strength. Formed for the collective defence against a common enemy, NATO did not dissolve when the Warsaw Pact disappeared, although its po- litical unity has begun to fade. The vulnerability – particularly of European citizens – that arises from a weak EU, weak national resolve and a weakened NATO is enormous when a combination of hostile actors and larger impersonal trends converge against Europe.

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  • In the recharge area, oxidising conditions occur and dissolution of calcium and bicarbonate dominates. As the water continues to move down dip, further modifications are at first limited. By observing the redox potential (Eh) of abstracted groundwater, a sharp redox barrier was detected beyond the edge of the confining layer, corresponding to the complete exhaustion of dissolved oxygen. Bicarbonate increases and the pH rises until buffering occurs at about 8.3.

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  • Total dissolved organic carbon (TOC) in waters is always one of important factors to assess water quality. In this paper, we propose a simple procedure based on carbon measurements by ANATOC II analyzer to estimate the total dissolved organic carbon in waters of the river system in Hanoi. Our results which were carried out during the year of 2003 showed that carbon contents in the dissolved faction in this river system existed mainly in the organic form and that TOC contents strongly influenced the vegetation and climate.

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  • A Abatement: Reducing the degree or intensity of, or eliminating, pollution. Abatement Debris: Waste from remediation activities. Absorbed Dose: In exposure assessment, the amount of a substance that penetrates an exposed organism's absorption barriers (e.g.,, skin, lung tissue, gastrointestinal tract) through physical or biological processes. The term is synonymous with internal dose. Absorption Barrier: Any of the exchange sites of the body that permit uptake of various substances at different rates (e.g., skin, lung tissue, and gastrointestinal-tract wall).

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  • Chitin that is a natural organic constituent has had high exchange value. The derivative of chitin is specially chitosan, which has had many applications on light industry, food, agriculture, medicine, and comestic… Makingsausaage casing; chitosan (3%) and 10% of mixed additives of PEG and EG (ratio1:1) are dissolved in a aqueous acetic acid solution, the acetic acid concentration of the solution is 1.5%. The solutions are used to make sausage casing for 35 minutes at 64 650C.

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  • Yadav et al. (2007) studied on fertilizer industrial discharge showed that some components in the discharge may interact with each other and produce toxic to aquatic organisms. For instance, the interaction between dissolved oxygen and ammonia changed the respiratory physiology in fresh water fish. In addition, results showed that the toxicity of the effluent in fish depends on concentration and duration of exposure.

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  • distortion in the cell organelles and inhibit the activity of various enzymes (Valarmathi & Azariah, 2003; Yadav et al., 2007), which may greatly disturb the physiological state of the exposed living organism. The heavy metals present in the fertilizer industry discharge are usually in dissolved state which could easily be uptaken by fish and enter human food chain. There have been studies showed that metals will cause damage to the human kidney and liver even at low concentration.

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  • Tham khảo sách 'humic substances in terrestrial ecosystems', khoa học tự nhiên, công nghệ sinh học phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả

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  • 15 Gas Exchange 1. Introduction In all organisms gas exchange, the supply of oxygen to and removal of carbon dioxide from cells, depends ultimately on the rate at which these gases diffuse in the dissolved state. The diffusion rate is proportional to the surface area over which diffusion is occurring.

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  • READING Water pollution is the introduction into fresh or ocean waters of chemical, physical, or biological material that degrades the quality of the water and affects the organisms living in it. This process ranges from simple addition of dissolved or suspended solids to discharge of the most insidious and persistent toxic pollutants (such as pesticides, heavy metals, and nondegradable, bioaccumulative, chemical compounds).

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  • Continental shelves are the gently sloping areas of the ocean floor, contiguous to the continent, that extend from the coastline to the shelf-break. The shelf break, which is located around 150–200 meters depth, is the area of the continental margin where there is an abrupt change between the shelf and the steeper continental slope. Primary production in the oceans, i.e. the production of organic compounds from dissolved carbon dioxide and nutrients through photosynthesis, is often associated with upwellings (Botsford et al., 2006).

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  • Sorption is a process by which chemicals or organisms become attached to soils and/or the geologic rock material (aquifer solids) and removed from the water. Often the sorption process is reversible and solutes desorb and hence dissolved-solute plumes are retarded, rather than solutes being permanently retained by the solids. Cation exchange is the interchange between cations in solution and cations on the surfaces of clay particles or organic colloids. Filtration is a process that affects particulate contaminants (e.g.

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  • Decreases in pH and ANC are often paral- leled by changes in element concentrations including increases in Al +3 concentrations and decreases in Ca +2 . High dissolved Al +3 concen- trations can have toxic effects on many types of aquatic biota, and at extreme levels few aquatic species can survive (Table 1). Organic forms of Al +3 are much less toxic than inorganic forms. Emerging research suggests that Ca +2 concentra- tions in streamwater are also an important bio- logical indicator.

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