A study of the water quality of the Potrero de los Funes River (San Luis – Argentina) was carried out in order to evaluate
the possible effect of the anthropogenic activities on the river developed in the homonymous town. Samples were collected
during the period March 2000–November 2005 at three selected sampling sites (RP1, RP2 and RP3). Different physicochemical and bacteriological parameters (turbidity, pH, conductivity, suspended solids, alkalinity, potassium,
sodium, calcium, magnesium, chlorides, nitrates, phosphates, sulphates, chemical oxygen demand (COD), 5-day biological oxygen
demand (BOD5), dissolved oxygen, total coliforms, Escherichia coli and total heterotrophic bacteria) were analysed according to the Standard Method for the Examination of Water and Wastewater.
When comparing the values of total coliforms, E. coli, total heterotrophic bacteria, COD, BOD5 and phosphates from the zone without anthropogenic influence (RP1) and the urban zones (RP2 and RP3) an important variation in the parameters was observed. These results indicate that the urban activity produces a serious
and negative effect on the water quality, thus constituting a sanitary risk and may have a major impact on the trophic status
of the Potrero de los Funes dam. As case study, we report on the use of General Quality Index (GQI) to evaluate spatial and
seasonal changes in the water quality of Potrero de los Funes River. Results revealed a significant degradation of the water
quality at RP2 and RP3. 相似文献
Current demand analysis methods do not formally cover the case of chronic deficits in quantity or quality of water and sanitation
services. These services include drinking water supply (DWS), wastewater and sewage treatment (WST), and municipal solid waste
management (MSW). Formal analysis of this case would, at minimum, define the deficit state and evaluate appropriate options
for reducing it. This paper proposes for a formal analytical model for municipal sanitation systems (MSS) that operate with
deficits in at least one of the constituent services of DWS, WST, or MSW. The model introduces definitions and notation for
describing the deficit state for conducting demand analysis on municipal sanitation systems. This model of demand analysis
for systems with chronic deficits will hereinafter be referred to as deficit analysis. A case study for Bacoor, Philippines is presented as an example. 相似文献
Environmental Science and Pollution Research - In this study, the essential oil (EO) from leaves of Croton linearis Jacq was extracted and characterized by GC/MS. The EO hydrophilic-lipophilic... 相似文献
This work proposes the quantification of Cr (VI) ions in natural waters in trace level, using activated alumina (Al2O3) as preconcentration support, controlled in-line dissolution of the solidified chromophore diphenylcarbazide after heat treatment and spectrophotometric detection. The manifold ensures high sensitivity of analytical response, good repeatability, and stability. In this work, optimization of experimental conditions of a flow injection system was chosen as the parameters for greater sensitivity and better selectivity. The selected optimized conditions were 0.30 mol L?1 for H2SO4 concentration, system flow rate as 0.40 mL min?1, sample injection volume of 192.50 μL, 2 min for preconcentration time, and 0.10 mol L?1 for eluent concentration. The analytical curves obtained for real sample analysis show linear range from 0.192 to 0.961 μM, linear correlation coefficient R?=?0.9997 and LOD?=?0.024 μM. The preconcentration factor of about four times was obtained through the passage of 800 μL of a standard solution containing 0.961 μM of Cr (VI) through mini-column of preconcentration followed by elution at 192.5 μL of NH4OH 0.1 mol L?1 solution. The solid chromogenic reagent presented high durability (weeks in daily use with mass of 0.0993 g) and good reproducibility in analytical signal. The reactivation of the mini-column of alumina should be executed after ten injections of eluent, using 800 μL of HCl 0.02 mol L?1 solution in flow through the same. Each cycle of injection and elution of the sample takes about 5 min on the proposed terms. Despite the length of each cycle still be high, low concentrations can be detected using a technique of relatively low cost. This is due in part, the association dissolution of the chromogenic reagent directly in the line and the preconcentration step. Another important factor is the economy of reagent chromogenic, low generation of reject contributing to better quality of the environment, and the high potential for applications to work in field. 相似文献
Different social-ecological systems around the world are managed under community-based natural resource management (CBNRM) strategies. This paper analyses how CBNRM strategies influence the resilience of social-ecological systems to the disturbances they face, drawing upon the experience of three Latin American cases (two in Mexico and one in Colombia). The cases differ in their CBNRM approach and in the time these governance systems have been in place. By using a mixed-method approach, we review the socio-ecological history and describe each CBNRM characteristics. We then assess their resilience to socioeconomic and environmental disturbances through a set of indicators. We found that CBNRM strategies influence positively and negatively resilience and that internal decisions might address important threats. On the positive side, the social-ecological systems with longer tradition of CBNRM and more local buy-in of commonly agreed objectives appear to be more resilient to environmental challenges. But, internal governance factors such as power imbalances, poor income distribution, and gender inequities linked to CBNRM undermine resilience and foster out migration. Finally, communities appear to have limited capacities to cope with external disturbances such as global drivers of change or national policies that negatively affect their social-ecological resilience.
Regional Environmental Change - The published online version contains mistake. Author name was incorrectly captured. Instead of Maria del Mar Delgado-Serrano was incorrectly captured as Ma del Mar... 相似文献
The Cu polyester thin-sputtered layers on textile fabrics show an acceptable bacterial inactivation kinetics using sputtering methods.
Materials and methods
Direct current magnetron sputtering (DCMS) for 40?s of Cu on cotton inactivated Escherichia coli within 30?min under visible light and within 120?min in the dark. For a longer DCMS time of 180?s, the Cu content was 0.294% w/w, but the bacterial inactivation kinetics under light was observed within 30?min, as was the case for the 40-s sputtered sample.
Results and discussion
This observation suggests that Cu ionic species play a key role in the E. coli inactivation and these species were further identified by X-ray photoelectron spectroscopy (XPS). The 40-s sputtered samples present the highest amount of Cu sites held in exposed positions interacting on the cotton with E. coli. Cu DC magnetron sputtering leads to thin metallic semi-transparent gray?Cbrown Cu coating composed by Cu nanoparticulate in the nanometer range as found by electron microscopy (EM). Cu cotton fabrics were also functionalized by bipolar asymmetric DCMSP.
Conclusion
Sputtering by DCMS and DCMSP for longer times lead to darker and more compact Cu films as detected by diffuse reflectance spectroscopy and EM. Cu is deposited on the polyester in the form of Cu2O and CuO as quantified by XPS. The redox interfacial reactions during bacterial inactivation involve changes in the Cu oxidation states and in the oxidation intermediates and were followed by XPS. High-power impulse magnetron sputtering (HIPIMS)-sputtered films show a low rugosity indicating that the texture of the Cu nanoparticulate films were smooth. The values of Rq and Ra were similar before and after the E. coli inactivation providing evidence for the stability of the HIPIMS-deposited Cu films. The Cu loading percentage required in the Cu films sputtered by HIPIMS to inactivate E. coli was about three times lower compared to DCMS films. This indicates a substantial Cu metal savings within the preparation of antibacterial films. 相似文献
This paper presents the results of the lixiviation of metals from different mixtures of fly and bottom ashes that have been stabilized and solidified in clays used in the manufacture of bricks. The ashes used for this study were obtained from a Hoffmann-type brick furnace adapted for the incineration of municipal solid waste during the manufacturing of ceramic bricks. The ashes were stabilized in clay in different proportions of clay:ash mix (99:1, 95:5, 90:10, 80:20 and 60:40). Such mixes were used to manufacture bricks that were calcined at a temperature ranging from 50 to 1100 degrees C. The clay, ashes and manufactured bricks were characterized using X-ray diffraction, fluorescent X-ray, thermogravimetry, differential thermal analysis, atomic absorption spectroscopy and scanning electronic microscopy. In addition, toxicity characteristic leaching procedure lixiviation tests were performed according to the EPA 1311 method for the determination of heavy metals. The results showed an affinity between clay and ash, and also that the bricks manufactured with these mixtures present low lixiviation levels. The tests also showed the highest decrease in the concentration of arsenic, nickel, chromium, zinc and silver for 99:1 mixtures. The 95:5 mixture was found to be the most favourable for the stabilization (greater concentration decrease) of lead and cadmium. Selenium was the metal with the lowest concentration change whereas arsenic, nickel, chromium, zinc and cadmium showed the greatest concentration change in all mixtures, with the exception of cadmium in the mixture 99:1. 相似文献
The Piratininga Lagoon is a coastal, choked, and brackish ecosystem in SE Brazil, where uncontrolled discharge of domestic sewage led to eutrophication, increasing massive proliferation of benthic macroalgae, and decrease of the lagoon mean depth. In 1992, a dam was constructed by the local Municipality at its tidal channel aiming at stabilising its water level. Main physico-chemical parameters, together with macroalgae biomass, nutrient concentrations in the water column, particulate organic carbon, and chlorophyll a were recorded monthly at 4 sampling stations within the Piratininga lagoon from April 1994 to April 1995. The data, compared with “before-lock” existing studies, show that nutrients and chlorophyll a concentrations significantly increased after the lock construction. Based on the functioning of the ecosystem, we propose to harvest the algal mats before their decomposition period in order to partly remove the nutrient stocks from the lagoon and the future ecosystem modelling to predict the impact of natural and anthropogenic eutrophication. 相似文献