the physico-chemical parameters, nutrient status and heavy metal ions of huluka and alaltu rivers of ambo, ethiopia were studied. temperature, ph, electrical conductivity, co2 content, total dissolved solids, hardness, dissolved oxygen, ca2+, mg2+, cl-, nitrate, phosphate and sulphate have been determined along with selected heavy metals to assess the various water quality profiles along the ri...

This study investigated the influence of dissolved oxygen concentration and aeration time on nitrification and nitrite accumulation in an attempt to optimize the recently developed biological-partial-nitritation process for the treatment of strong nitrogen wastewaters. Investigation of dissolved oxygen concentration on ammonium and nitrite oxidation was carried out in a batch reactor. The disso...

methane is one of the important greenhouse gases that contribute to a rise in global mean surface temperature. aquatic environments are postulated to contribute > 50% of the total global methane (ch4) flux to the atmosphere (de angelis and lilley, 1987). dissolved methane concentration in surface waters was measured from january to december 2008 at two selected sites upper reaches (ongc bridge)...

Question: How does optimal size at the beginning of the juvenile stage vary with dissolved oxygen and aquatic predator pressure? Mathematical methods: An implicit model based on earlier offspring size and number optimality models, using empirical observations to motivate and interpret the results. Key assumptions: A stable, density-independent system with high parental care that maximizes mater...

in this study the effect of nitrogen form and different oxygen levels on growth and development and macronutrients concentrations in lettuce plants was investigated. this investigation showed that sole ammonium application caused fresh and dry weight reduction of shoot and root in lettuce plant. but different oxygen levels had no effect on them. nitrogen concentration of shoot was higher in amm...

This paper describes an experimental study of the stability of an HPAM polymer and an HPAM-ATBS terpolymer in the presence of varying initial levels of dissolved oxygen (0 to 8000 parts per billion, ppb), Fe (0 to 220 parts per million, ppm), and Fe (0 to 172 ppm). A special method was developed to attain and confirm dissolved oxygen levels. Stability studies were performed at 23°C and 90°C. Fo...

INTRODUCTION We investigated whether adding ultrafine (nano-scale) oxygen-carrying bubbles to water concurrently with dissolved carbon-dioxide (CO2) could result in safe, long-duration anesthesia for fish. RESULTS To confirm the lethal effects of CO2 alone, fishes were anesthetized with dissolved CO2 in 20°C seawater. Within 30 minutes, all fishes, regardless of species, died suddenly due to ...

Abstract. Hyriopsis Cumingii is Chinese major fresh water pearl mussel, widely distributed in the southern provinces of China's large and medium-sized freshwater lakes. In the management of Hyriopsis Cumingii ponds, dissolved oxygen (DO) is the key point to measure, predict and control. In this study, we analyzes the important factors for predicting dissolved oxygen of Hyriopsis Cumingii ponds...

BACKGROUND One of the primary goals of critical care medicine is to support adequate gas exchange without iatrogenic sequelae. An emerging method of delivering supplemental oxygen is intravenously rather than via the traditional inhalation route. The objective of this study was to evaluate the gas-exchange effects of infusing cold intravenous (IV) fluids containing very high partial pressures o...

In the present study, different oxygen levels were examined in two weight groups of great sturgeon Huso huso including small size (with initial weight 280.9 ± 49.2 g) and large size (with initial weight 1217.9 ± 138.1 g). The fish were kept in hypoxia (2-3 mg/l), normoxia (5-6 mg/l) and hyperoxia (9-10 mg/l) conditions for 8 weeks and then were individually placed in the tanks with oxygen lev...