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Water Used (water + used)
Selected AbstractsWide-area estimates of saltcedar (Tamarix spp.) evapotranspiration on the lower Colorado River measured by heat balance and remote sensing methods,,ECOHYDROLOGY, Issue 1 2009Pamela L. Nagler Abstract In many places along the lower Colorado River, saltcedar (Tamarix spp) has replaced the native shrubs and trees, including arrowweed, mesquite, cottonwood and willows. Some have advocated that by removing saltcedar, we could save water and create environments more favourable to these native species. To test these assumptions we compared sap flux measurements of water used by native species in contrast to saltcedar, and compared soil salinity, ground water depth and soil moisture across a gradient of 200,1500 m from the river's edge on a floodplain terrace at Cibola National Wildlife Refuge (CNWR). We found that the fraction of land covered (fc) with vegetation in 2005,2007 was similar to that occupied by native vegetation in 1938 using satellite-derived estimates and reprocessed aerial photographs scaled to comparable spatial resolutions (3,4 m). We converted fc to estimates of leaf area index (LAI) through point sampling and destructive analyses (r2 = 0·82). Saltcedar LAI averaged 2·54 with an fc of 0·80, and reached a maximum of 3·7 with an fc of 0·95. The ranges in fc and LAI are similar to those reported for native vegetation elsewhere and from the 1938 photographs over the study site. On-site measurements of water use and soil and aquifer properties confirmed that although saltcedar grows in areas where salinity has increased much better than native shrubs and trees, rates of transpiration are similar. Annual water use over CNWR was about 1·15 m year,1. Copyright © 2008 John Wiley & Sons, Ltd. [source] Observed and predicted reproduction of Ceriodaphnia dubia exposed to chloride, sulfate, and bicarbonate,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2010Peter J. Lasier Abstract Chronic toxicities of Cl,, SO, and HCO to Ceriodaphnia dubia were evaluated in low- and moderate-hardness waters using a three-brood reproduction test method. Toxicity tests of anion mixtures were used to determine interaction effects and to produce models predicting C. dubia reproduction. Effluents diluted with low- and moderate-hardness waters were tested with animals acclimated to low- and moderate-hardness conditions to evaluate the models and to assess the effects of hardness and acclimation. Sulfate was significantly less toxic than Cl, and HCO in both types of water. Chloride and HCO toxicities were similar in low-hardness water, but HCO was the most toxic in moderate-hardness water. Low acute-to-chronic ratios indicate that toxicities of these anions will decrease quickly with dilution. Hardness significantly reduced Cl, and SO toxicity but had little effect on HCO. Chloride toxicity decreased with an increase in Na+ concentration, and HCO toxicity may have been reduced by the dissolved organic carbon in effluent. Multivariate models using measured anion concentrations in effluents with low to moderate hardness levels provided fairly accurate predictions of reproduction. Determinations of toxicity for several effluents differed significantly depending on the hardness of the dilution water and the hardness of the water used to culture test animals. These results can be used to predict the contribution of elevated anion concentrations to the chronic toxicity of effluents; to identify effluents that are toxic due to contaminants other than Cl,, SO, and HCO; and to provide a basis for chemical substitutions in manufacturing processes. Environ. Toxicol. Chem. 2010;29:347,358. Published 2009 SETAC [source] Isotope Methods for Management of Shared Aquifers in Northern AfricaGROUND WATER, Issue 5 2005Bill Wallin Access to fresh water is one of the major issues of northern and sub-Saharan Africa. The majority of the fresh water used for drinking and irrigation is obtained from large ground water basins where there is minor contemporary recharge and the aquifers cross national borders. These aquifers include the Nubian Aquifer System shared by Chad, Egypt, Libya, and Sudan; the Iullemeden Aquifer System, extending over Niger, Nigeria, Mali, Benin, and Algeria; and the Northwest Sahara Aquifer System shared by Algeria, Libya, and Tunisia. These resources are subject to increased exploitation and may be severely stressed if not managed properly as witnessed already by declining water levels. In order to make appropriate decisions for the sustainable management of these shared water resources, planners and managers in different countries need an improved knowledge base of hydrological information. Three technical cooperation projects related to aquifer systems will be implemented by the International Atomic Energy Agency, in collaboration with the United Nations Educational, Scientific and Cultural Organization and United Nations Development Programme/Global Environmental Facility. These projects focus on isotope hydrology studies to better quantify ground water recharge and dynamics. The multiple isotope approach combining commonly used isotopes 18O and 2H together with more recently developed techniques (chlorofluorocarbons, 36Cl, noble gases) will be applied to improve the conceptual model to study stratification and ground water flows. Moreover, the isotopes will be an important indicator of changes in the aquifer due to water abstraction, and therefore they will assist in the effort to establish a sustainable ground water management. [source] Soil moisture dynamics in an eastern Amazonian tropical forestHYDROLOGICAL PROCESSES, Issue 12 2006Rogério D. Bruno Abstract We used frequency-domain reflectometry to make continuous, high-resolution measurements for 22 months of the soil moisture to a depth of 10 m in an Amazonian rain forest. We then used these data to determine how soil moisture varies on diel, seasonal and multi-year timescales, and to better understand the quantitative and mechanistic relationships between soil moisture and forest evapotranspiration. The mean annual precipitation at the site was over 1900 mm. The field capacity was approximately 0·53 m3 m,3 and was nearly uniform with soil depth. Soil moisture decreased at all levels during the dry season, with the minimum of 0·38 m3 m,3 at 3 m beneath the surface. The moisture in the upper 1 m showed a strong diel cycle with daytime depletion due to evapotranspiration. The moisture beneath 1 m declined during both day and night due to the combined effects of evapotranspiration, drainage and a nighttime upward movement of water. The depth of active water withdrawal changed markedly over the year. The upper 2 m of soil supplied ,56% of the water used for evapotranspiration in the wet season and ,28% of the water used in the dry season. The zone of active water withdrawal extended to a depth of at least 10 m. The day-to-day rates of moisture withdrawal from the upper 10 m of soil during rain-free periods agreed well with simultaneous measurements of whole-forest evapotranspiration made by the eddy covariance technique. The forest at the site was well adapted to the normal cycle of wet and dry seasons, and the dry season had only a small effect on the rates of land,atmosphere water vapour exchange. Copyright © 2006 John Wiley & Sons, Ltd. [source] Demand side management for water heating installations in South African commercial buildingsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 4 2001P. G. Rousseau Abstract The largest percentage of the sanitary hot water used in South African buildings is heated by means of direct electrical resistance heaters. This is one of the major contributing factors of the undesirable high morning and afternoon peaks imposed on the national electricity supply grid. Water heating therefore continues to be of concern to ESKOM, the country's only electrical utility company. The so-called in-line water heating system design methodology was developed to address this problem. This paper investigates the potential impact of in-line systems on the national peak electrical demand. A computer simulation model was developed that combines a deterministic mathematical model with a statistical approach in order to predict the diversity factors associated with both the existing and in-line design methodologies. A study was also conducted to estimate the total installed water heating capacity in the national commercial building sector. This figure can be combined with the simulated diversity factor to determine the peak electrical demand. The deterministic model includes the detailed simulation of the hot water storage vessel, the electrical heater and the system control algorithm. The mathematical model for the storage vessel is based on an electrical analogue approach that includes the effects of conduction as well as forced and natural convection. This model was verified extensively with the aid of laboratory measurements and compared with existing storage vessel models. It was found that the new storage vessel model could predict the supply temperature within 2 per cent for a system configuration with the heater in parallel outside the reservoir and within 12 per cent for a configuration with the heater situated inside the reservoir. This compares favourably with existing models found in the literature. The complete simulation based on the statistical approach showed that extensive application of the new design methodology could result in a reduction of approximately 75 MW in the total maximum peak demand imposed on the electricity supply grid in wintertime. This is 58 per cent of the current peak demand due to commercial water heating and 12.5 per cent of the peak load reduction target set by ESKOM until the year 2015. Copyright © 2001 John Wiley & Sons, Ltd. [source] Renal silica calculi in an infantINTERNATIONAL JOURNAL OF UROLOGY, Issue 2 2004TOSHIYUKI NISHIZONO Abstract, We report on a rare case of urinary silica calculi in a 10-month-old boy. The boy showed acute pyelonephritis with left hydronephrosis. Ultrasonography and computed tomography revealed a calculus at the left ureteropelvic junction and three additional calculi in the left renal pelvis. Because his acute pyelonephritis was refractory to conventional chemotherapy, the patient underwent successful left percutaneous nephrostomy followed by percutaneous nephrolithotripsy for the renal calculi. All stones disappeared and his postoperative course was uneventful. On infrared spectrophotometry, the wavelength pattern of the stones exhibited two peaks at 1100 and 1650 cm,1, consistent with the determination that the calculi consisted of a mixture of silicate (78%) and calcium oxalate (22%). We consider that the etiology of the calculi in this child can be ascribed to the silicate-rich water used to dilute milk. In Japan, 46 adult patients with urinary silicate calculi have been reported in the literature; however, there is no report of the disease in an infant in Japan. [source] Urban and industrial water use in the Krishna Basin, India,IRRIGATION AND DRAINAGE, Issue 4 2009Daniel J. Van Rooijen Bassin Krishna; utilisation urbaine de l'eau; utilisation industrielle de l'eau; modélisation Abstract Regional urbanization and industrial development require water that may put additional pressure on available water resources and threaten water quality in developing countries. In this study we use a combination of census statistics, case studies, and a simple model of demand growth to assess current and future urban and industrial water demand in the Krishna Basin in southern India. Water use in this "closed" basin is dominated by irrigation (61.9 billion cubic metres (BCM) yr,1) compared to a modest domestic and industrial water use (1.6 and 3.2 BCM yr,1). Total water diversion for non-irrigation purposes is estimated at 7,8% of available surface water in the basin in an average year. Thermal power plants use the majority of water used by industries (86% or 2.7 BCM yr,1), though only 6.8% of this is consumed via evaporation. Simple modelling of urban and industrial growth suggests that non-agricultural water demand will range from 10 to 20 BCM by 2030. This is 14,28% of basin water available surface water for an average year and 17,34% for a year with 75% dependable flow. Although water use in the Krishna Basin will continue to be dominated by agriculture, water stress, and the fraction of water supplies at risk of becoming polluted by urban and industrial activity, will become more severe in urbanized regions in dry years. Copyright © 2008 John Wiley & Sons, Ltd. L'urbanisation régionale et le développement industriel demandent de l'eau, ce qui peut augmenter la pression sur les ressources en eau disponibles dans les pays en développement. Dans cette étude nous utilisons une combinaison de données de recensement, des études de cas et un modèle simple de croissance de la demande pour évaluer la demande en eau urbaine et industrielle actuelle et future dans le bassin Krishna en Inde du sud. Les usages de l'eau dans ce bassin « fermé » sont dominés par l'irrigation (61.9 milliards de m3/an) alors que les usages domestiques et industriels sont modestes (1.6 et 3.2 milliards de m3/an). L'eau utilisée en dehors de l'irrigation est estimée à 7 ,8% de l'eau de surface disponible dans le bassin en année moyenne. Les centrales thermiques utilisent la plus grosse partie de l'eau allouée aux industries (86% ou 2.7 milliards de m3/an) bien que seulement 6.8% de cette quantité soit consommé par évaporation. Une modélisation simple de la croissance urbaine et industrielle suggère que la demande non-agricole d'eau variera de 10 à 20 milliards de m3/an d'ici à 2030. C'est 14,28% de l'eau de surface disponible du bassin en année moyenne et 17,34% de l'écoulement garanti à 75%. Bien que l'utilisation de l'eau dans le bassin Krishna continue à être dominée par l'agriculture, la tension sur l'eau peut devenir plus sévère en année sèche dans les régions urbanisées avec en outre le risque d'une pollution par l'activité urbaine et industrielle. Copyright © 2008 John Wiley & Sons, Ltd. [source] Bacterial population dynamics and community structure in a pharmaceutical manufacturing water supply system determined by real-time PCR and PCR-denaturing gradient gel electrophoresisJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2004M. Kawai Abstract Aims:, To control bacteria in the pharmaceutical water supply system. Methods and Results:, Bacteria were enumerated by conventional culture method and fluorescent vital staining. Activated carbon treatment and storage in a tank provided favourable environments for bacterial growth. The bacterial population of the water in both the post-activated carbon treatment and the tank was analysed by denaturing gradient gel electrophoresis (DGGE) with PCR-amplified 16S rDNA fragments including V6, -7, and -8 regions. The bacterial community structure in activated carbon treated water was stable throughout the year. Several kinds of bacteria such as genus Aquaspirillum and Methylobacterium were found in the water after activated carbon treatment. The bacterial community structure was changed and other bacteria such as mycobacteria were detected after storage. Mycobacteria were quantified in water samples using real-time PCR targeting the 16S rDNA gene. Mycobacteria were also detected in tap water and their number was increased 103,104 -fold higher after storage. Conclusion:, These data suggest the importance of culture-independent methods for quality control of water used in pharmaceutical manufacturing. Significance and Impact of the Study:, Critical steps and specified bacteria that should be controlled in the water supply system were recognized by culture-independent methods. These data will enable effective control of water used in the pharmaceutical industry. [source] Prevalence and virulence properties of Vibrio cholerae non-O1, Aeromonas spp. and Plesiomonas shigelloides isolated from Cambé Stream (State of Paraná, Brazil)JOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2000A. Gibotti The incidence of Vibrio cholerae, Aeromonas spp. and Plesiomonas shigelloides was determined in water samples from Cambé Stream. The samples were collected from seven different sites. The serogroups, virulence markers and drug resistance profiles were also evaluated. Twelve Aer. hydrophila, 12 Aer. caviae, eight Aer. sobria, seven Ple shigelloides and two V. cholerae non-O1 were isolated. They belonged to different serogroups and all produced haemolysis in different assays. Five of the Aeromonas strains and one of V. cholerae non-O1 were positive for enterotoxin activity. Haemagglutination and its inhibition, using erythrocytes of different origins, was variable for Aeromonas spp. and V. cholerae, while none of the Ple. shigelloides haemagglutinated in association with any type of erythrocyte. All isolates exhibited multiple drug resistance. These results indicate that the occurrence of V. cholerae non-O1, Aeromonas spp. and Ple. shigelloides, in water used for vegetable irrigation, human recreation and animal consumption, among others, represents a potential risk for humans. [source] The effect of water on particle size, porosity and the rate of drug release from implanted titania reservoirsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2010Tessy Lopez Abstract The implantation of controlled drug release devices represents a new strategy in the treatment of neurodegenerative disorders. Sol,gel titania implants filled with valproic acid, have been used for this purpose to treat induced epilepsy in rats. The kinetics of the drug release depend on: (a) porosity, (b) chemical interactions between valproic acid and surface hydroxyl groups of titania, (c) particle size, and (d) particle size agglomerates. The concentration of water used in the hydrolysis reaction is an important variable in the degree of porosity, hydroxylation, and structural defects of the nanostructured titanium oxide reservoir. The titanium n -butoxide/water ratio was systematically varied during the sol,gel synthesis, while maintaining the amount of valproic acid constant. Characterization studies were performed using DTA-TGA, FTIR, Raman, TEM, SEM, BET, and in vitro release kinetic measurements. The particle agglomerate size and porosity were found to depend on the amount of water used in the sol,gel reaction. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010 [source] SENSORY EVALUATION OF COOKED RICE IN RELATION TO WATER-TO-RICE RATIO AND PHYSICOCHEMICAL PROPERTIESJOURNAL OF TEXTURE STUDIES, Issue 1 2007WEENA SRISAWAS ABSTRACT The effects of cooking water-to-rice (W/R) ratio on the sensory characteristics of cooked rice eating quality of 14 varieties of Thai rice were investigated in relation to their physicochemical properties. Milled rice samples were cooked with five W/R ratios ranging from 1.3 to 2.5 on a weight basis and presented to 12 trained panelists for sensory evaluation. A three-way analysis of variance and a principal component analysis identified the intensity of sensory hardness as the main characteristic of cooked rice. It decreased with increasing W/R ratio whereas sensory stickiness decreased. The overall acceptability based on appearance, texture and flavor attributes reached peak levels corresponding to optimum W/R ratios for different rice varieties, and was highly correlated with sensory hardness and stickiness. Partial least squares regression models of optimum W/R ratio and peak overall acceptability gave coefficients of determination of 0.991 and 0.980, respectively, thus indicating that the optimum W/R ratio and the acceptability ratings of cooked rice could be reliably predicted from the physicochemical properties such as the apparent amylose content, protein content, gel consistency, alkali-spreading value and grain elongation ratio of milled rice. PRACTICAL APPLICATIONS Sensory evaluation of cooked rice eating qualities is a difficult task to carry out routinely on a day-to-day basis. Presently, rice varieties are categorized according to grain dimensions and selective physicochemical traits that reflect on the eating quality of cooked rice. Though it has been long realized that the amount of water used for cooking and rice physicochemical properties highly influence the eating quality of cooked rice, no information is currently available on the quantitative evaluation of these factors. Results of this study showed that models could be developed to quantify the optimum amount of water for cooking rice of different varieties with the most desirable sensory eating qualities. The prediction of peak overall sensory acceptability scores that correspond to the optimum cooking water-to-rice ratio could be useful for categorizing rice varieties based on their impact on sensory eating quality and for the development of baseline information for consumers by the rice industry. [source] Olive oil mineral content of two local genotypes as influenced by recycled effluent irrigation under arid environmentJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2009Khaled M Al-Absi Abstract BACKGROUND: An alternative plan for saving scarce water could include use of non-conventional water resources such as reclaimed wastewater originating from wastewater treatment plants. The main health risks are associated with contamination of crops by wastewater due to its chemical composition. Therefore, the effect of recycled effluent irrigation was investigated on mineral composition and quality of olive oil of two local olive cultivars under field conditions during two complete cycles. RESULTS: The treated wastewater used in this study was taken from the HUIE Wastewater Treatment Plant. This water is mainly generated by textile firms, mixed with municipal domestic effluent. The analysis of the effluent indicated that element concentrations fall within the permissible range in irrigation water used for plants. The concentrations of mineral composition were relatively higher in olive oils irrigated with treated wastewater but lower than the maximum permissible concentration. Concentrations ranged from 8.91 to 26.16 mg kg,1 for Ca; 6.25,16.11 mg kg,1 for Na, 53.20,111.76 mg kg,1 for K, 0.19,0.36 mg kg,1 for Zn, 0.97,1.46 mg kg,1 for Mn and 0.07,0.13% for Cl. No statistically significant differences were found between the oil quality indices (peroxide and acidity). CONCLUSION: These results indicate that this kind of effluent is suitable for irrigation of olive genotypes grown for oil purposes. Copyright © 2009 Society of Chemical Industry [source] Effects of water storage in the stele on measurements of the hydraulics of young roots of corn and barleyNEW PHYTOLOGIST, Issue 3 2009Ankur Joshi Summary ,,In standard techniques (root pressure probe or high-pressure flowmeter), the hydraulic conductivity of roots is calculated from transients of root pressure using responses following step changes in volume or pressure, which may be affected by a storage of water in the stele. ,,Storage effects were examined using both experimental data of root pressure relaxations and clamps and a physical capacity model. Young roots of corn and barley were treated as a three-compartment system, comprising a serial arrangement of xylem/probe, stele and outside medium/cortex. The hydraulic conductivities of the endodermis and of xylem vessels were derived from experimental data. The lower limit of the storage capacity of stelar tissue was caused by the compressibility of water. This was subsequently increased to account for realistic storage capacities of the stele. ,,When root water storage was varied over up to five orders of magnitude, the results of simulations showed that storage effects could not explain the experimental data, suggesting a major contribution of effects other than water storage. ,,It is concluded that initial water flows may be used to measure root hydraulic conductivity provided that the volumes of water used are much larger than the volumes stored. [source] Forward Osmosis Process for Dialysis Fluid RegenerationARTIFICIAL ORGANS, Issue 12 2009Khaled Mohamed Talaat Abstract In a preliminary experiment, 38% of the spent dialysis fluid water was reclaimed by a forward osmosis process through a cellulose triacetate membrane. The simplicity of forward osmosis and its minimal external energy requirements may allow the construction of a small bulk device that can reclaim a considerable portion of the water used in the patient's dialysis process. For developing an acceptable ambulatory dialysis system, decreasing the bulk of the fluid and equipment carried on the patient is essential. Forward osmosis may feasibly be used for dialysis fluid regeneration in ambulatory dialysis systems. [source] An empirical assessment of the value of irrigation water: the case study of Murrumbidgee catchment,AUSTRALIAN JOURNAL OF AGRICULTURAL & RESOURCE ECONOMICS, Issue 1 2010Muhammad Ejaz Qureshi Evaluation of value of irrigation water is essential for supporting policy decision making relating to investments in the irrigation sector, efficient allocation of irrigation water and water pricing and for crafting policies to compare the variable impacts of water reform within and across sectors of the economy. This paper asks the question of how much an established irrigator would pay for water and at what price farmers planning to expand the area they have under irrigation would consider paying for the right to access water. An analytical framework is developed to estimate the net present value of both annual and perennial agricultural activities in the Murrumbidgee catchment. Using these estimates the total value of water used in Murrumbidgee catchment is estimated. An aggregate water supply curve is derived for the catchment from where water may be acquired from irrigators for environmental flows. [source] Water conservation in surgery: A comparison of two surgical scrub techniques demonstrating the amount of water saved using a ,taps on/taps off' techniqueAUSTRALIAN JOURNAL OF RURAL HEALTH, Issue 4 2009Joshua Petterwood Abstract Objective:,Australia finds itself in the grip of its worst drought on record. The surgical profession has a responsibility to conserve water where possible. We tried to show how much water we saved through the simple measure of turning taps off while not in use during the surgical scrub. Design:,We conducted a prospective analysis of two different scrub techniques at the Gold Coast Hospital in Queensland, Australia. Ten participants completed two 5-min scrubs using standard ,elbow on' taps. In the first, they left the taps running throughout the scrub; in the second, they turned the taps on and off so that water ran only when rinsing the hands. Water was collected and the amount of time the hands spent under running water was recorded. Main outcome measure:,Amount of water used during the surgical scrub. Results:,A mean of 15.5 L was used during the ,taps on' scrub, with participants spending a mean of 47 s rinsing the hands. During the ,taps on/off' scrub, participants used a mean of 4.5 L, spending 40 s rinsing the hands. This represents a water saving of 11 L or 71% for each scrub (P < 0.001). There was a difference of 7 s in time rinsing the hands (P = 0.16). Conclusion:,A taps on/off technique is a simple and effective way of conserving large amounts of water during the surgical scrub. The technique should be adopted as standard practice. [source] Chiral sign selection on the J-aggregates of diprotonated tetrakis-(4-sulfonatophenyl)porphyrin by traces of unidentified chiral contaminants present in the ultra-pure water used as solventCHIRALITY, Issue 4 2009Zoubir El-Hachemi Abstract Traces of biological contaminants that cannot be detected, but are expected to be present, in ultra-pure water suffice to select the emerging chiral sign in the spontaneous mirror symmetry breaking that takes place during the formation of the J-aggregates of the amphiphilic diprotonated tetrakis-(4-sulfonatophenyl)porphyrin (H4TPPS42,). This is demonstrated by competition experiments with a chiral cationic surfactant. The sensitivity of the detection depends on the hierarchical control of the H4TPPS42, self-aggregation. Chirality 21:408-412, 2009. © 2008 Wiley-Liss, Inc. [source] Mutagenicity and disinfection by-products in surface drinking water disinfected with peracetic acidENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2002Silvano Monarca Abstract The aims of this research were to study the influence of peracetic acid (PAA) on the formation of mutagens in surface waters used for human consumption and to assess its potential application for the disinfection of drinking water. The results obtained using PAA were compared to those found with sodium hypochlorite (NaClO) and chlorine dioxide (ClO2). The Ames test, root anaphase aberration assay, and root/micronuclei assay in Allium cepa and Tradescantia/micronuclei test were used to evaluate the mutagenicity of disinfected samples. Microbiological tests were also performed, and disinfection by-products (DBPs) were identified using gas chromatography/mass spectrometry (GC/MS). A slight bacterial mutagenicity was found in raw lake and river water, and similar activity was detected in disinfected samples. A plant test revealed genotoxicity in raw river water, and microbiological analysis showed that PAA has bactericidal activity but lower than that of the other disinfectants. The DBPs produced by PAA were mainly carboxylic acids, which are not recognized as mutagenic, whereas the waters treated with the other disinfectants showed the presence of mutagenic/carcinogenic halogenated DBPs. However, additional experiments should be performed with higher concentrations of PAA and using water with higher organic carbon content to better evaluate this disinfectant. [source] Adsorption of Magnesium by Bottom Soils in Inland Brackish Water Shrimp Ponds in AlabamaJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 4 2010Harvey J. Pine Low-salinity (2.0,9.0 g/L) well waters used for inland culture of marine shrimp in Alabama are imbalanced with respect to ionic composition. Inputs of potassium (muriate of potash) and potassium-magnesium sulfate (Kmag®) fertilizers are used to correct these imbalances. Potassium is lost in overflow and intentional discharge, seepage, and through adsorption by bottom soils by exchangeable and non-exchangeable processes. This study was initiated to determine if bottom soils removed magnesium in the same manner as potassium. Laboratory soil,water mesocosms revealed that soils strongly adsorbed magnesium. The rate of adsorption tended to decline over time, indicating establishment of the equilibrium. Magnesium losses for the three soils ranged from 1405 to 1713 mg/tank (average = 1568 mg/tank). The cation exchange capacity (CEC) of the soils varied from 10.4 to 44.0 cmolc/kg (average = 24.6cmolc/kg). The decline in magnesium increased with higher soil CEC. In another trial, repeated exposures of soils to solutions of 40 mg Mg2+/L failed to saturate exchange sites, but rather maintained equilibrium with other base cations on soil adsorption sites. Dissolved sulfate resulting from additions of magnesium with magnesium sulfate heptahydrate (MgSO4·7H2O) was also monitored. Although difficulties of analysis occurred, sulfate was not adsorbed appreciably by the soils. [source] Microbial and nutrient pollution in the coastal bathing waters of Dar es SalaamAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue S1 2009Thomas J. Lyimo Abstract 1.The objective of the present study was to assess the microbial and nutrient quality of coastal beach waters used for bathing in the city of Dar es Salaam, Tanzania. Concentrations of traditional and alternative microbial indicators of faecal pollution and nutrients were assessed over a 1 year period (August 2005 to August 2006) using standard methods and the results were compared with the WHO water quality guidelines. 2.Faecal indicator bacteria values varied in a consistent fashion and correlated significantly with eachother, reflecting the presumed human faecal pollution. 3.The maximum counts (MPN per 100,mL) were observed on the site close to the city centre (Ocean Road) throughout the sampling period where values ranged from 1700 to>240 000 total coliform (TC), 200 to 92000 faecal coliform (FC) and 11 to 4900 enterococci (ENT). Other sites showed less predictable results with a range of values from 0,920, 0,540 and 0,46 for TC, FC and ENT, respectively. Furthermore, the faecal indicator bacteria concentration varied significantly with sampling time (P<0.05) and between sampling points (P<0.05). 4.Similarly, nutrients were significantly higher (P<0.05) at Ocean Road where concentration (µmolL,1) ranges were 0.2,54 (NO3), 0.0,20 (NO2) and 0.3,45 (PO4). 5.The levels of faecal indicator bacteria and nutrients were higher during the rainy seasons than the dry seasons, showing the inclusion of rain run-off as a source of contamination. The faecal indicator bacteria correlated positively with nutrients in both 1 year and daily data sets (P<0.01). Positive relationships were also observed among faecal indicators. This strongly suggests that an important role is played by sewage contamination in the extent of microbial pollution at the studied urbanized coastal beaches. Copyright © 2009 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||