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  • Open access
  • 12 Reads
Applying SPOT images to study the Colorado River effects on the Upper Gulf of California

Sediment discharges from rivers play a key role in downstream ecosystems, both for ecosystem morphology (e.g. deltas) and productivity. However, construction of dams and river regulation dramatically alter sediment transport. Currently, the Colorado River delta is one of the most transformed deltas in the world and no flow reaches the Gulf of California in most of the years. In this study, we used satellite images for the observation and measurement of coastal waters turbidity in the Upper Gulf of California (UGC) and Colorado River Delta (CRD). Specifically, we used SPOT high spatial resolution satellite. We processed images of the wavelength 2 (610-680 nm) from the period between 2008 and 2013 in the Biosphere Reserve area. Results showed that suspended material and high turbidity predominate in the CRD and intertidal zones of the UGC. High and very high turbidity values were due to two opposite coastal transport components along the Sonora and Baja California coasts. The high spatial resolution of the SPOT sensor effectively allowed locating the sediment transport gradients and the accumulation zones in a highly variable area. This information provided by SPOT images can be very valuable for management decisions such as the amount of ecological flow that needs to be released. This area is the habitat of endangered species, such as totoaba (Totoaba macdonaldi) and vaquita (Phocoena sinus), that are seriously affected by the loss of estuarine conditions. High resolution satellite images can help in quantifying the true extent of corrective measures.

  • Open access
  • 11 Reads
Total, dissolved and particulate N: P stoichiometry in prairie streams in relation to land cover and hydrologic variability

Concentrations and loads of nitrogen (N) and phosphorus (P), in both dissolved and particulate fractions, are sensitive to land cover and hydrologic variability. Previous studies on relationships between watershed characteristics and stream chemistry have focused on the response of individual N and P fractions. However, marine and lakes studies have shown the value of using individual nutrient fractions as well as nutrient ratios (e.g., N:P) to assess ecosystem condition. This study examined the response of total, dissolved, and particulate N and P fractions as well as N:P ratios to changes in % crop cover and hydrologic variability in three agricultural catchments in the Red River Basin, southern Manitoba, Canada. While discharge peaks were greatest during snowmelt for both study years (2013 and 2014), flow ceased in early June 2013 due to lack of precipitation whereas discharge peaks were observed during summer and fall 2014 in response to persistent multi-day rain events. Despite hydrologic differences between the two years, total, dissolved, and particulate N:P concentration ratios did not differ (p>0.05) between years (expressed as either annual or seasonal means) or in response to % crop cover. In contrast, N: P load ratios were associated with watershed characteristics: total N: P load ratios differed (p<0.05) in relation to both % crop cover and season, dissolved N:P load ratios differed (p<0.05) with % crop cover, and particulate N:P load ratios differed (p<0.05) between seasons and years. Our finding that dissolved versus particulate N:P load ratios responded differently to land use and hydrologic changes suggests the dissolved load ratios are more closely linked to land use activities whereas particulate loads ratios are largely influenced by interannual climate and discharge variability. Improved knowledge of the dominant nutrient forms and their transport pathways will assist in determining appropriate mitigation practices to reduce nutrient loads under a changing climate.

  • Open access
  • 7 Reads
ENERGY EFFICIENCY ANALYSIS OF WHEAT CROP UNDER DIFFERENT CLIMATE AND SOIL BASED IRRIGATION SCHEDULES

Use of energy in agriculture sector directly or indirectly has been intensified to increase crop production the agriculture sector directly or indirectly has been intensified to increase crop production to the agriculture sector directly or indirectly has been intensified to increase crop production to fulfill the food demand of the growing population. Considering the energy and water scarcity in Pakistan, the present study was carried out to assess wheat production efficiency with regard to energy consumption. For thi s purpose, a field experiment was conducted at the Water Management Research Centre (WMRC), University of Agriculture Faisalabad to compare two irrigation scheduling techniques (climatic and soil moisture based) and farmer’s practice. All the inputs except volume of irrigation water were same for all treatments. Energy equivalents (extracted from scientific source) were used to calculate energy balance and indices (Energy use efficiency, Energy Productivity (kg MJ the same for all treatments. Energy equivalents (extracted from scientific source) were used to calculate energy balance and indices (Energy use efficiency, Energy Productivity (kg MJ-1), specific energy (MJ.kg-1), Net energy (MJ ha-1) and Water productivity (kg m-3)). Results shows that the soil moisture based treatment (at 30% MAD) gave 7.94% and 27.94% more yield compared to climate based treatment’s (20 mm CPE) and farmer’s practice respectively. The pumping water for irrigation was the highest energy consumption input for wheat production after chemical fertilizers. Soil moisture and climate based treatments saved 33.72% and 35.72% energy respectively due to water saving over farmer practice. The highest net energy (78855.35 MJ ha-1), energy use efficiency (4.643011), energy productivity (0.200964 kg MJ-1) and water productivity (1.875 kg m-3) was achieved with soil moisture based irrigation schedule at 30% MAD however highest specific energy (7.097692 MJ.kg-1) was achieved with farmer practice.

  • Open access
  • 12 Reads
Quantitative Microbial Risk Assessment of Campylobacter for roof-harvested rainwater domestic use

Roof harvested rainwater (RHRW) use has become a very widespread technique in Brazilian rural communities, especially in regions with low water security. Since 2003, more than 500,000 cisterns were built in order to provide access to fresh water for communities in the Northeast region alone. Seeking to address the health concerns that may arise from this practice, the present study evaluated the microbiological risk for roof-harvested rainwater (RHRW) domestic use, with Campylobacter as the pathogenic microorganism of reference, through a Quantitative Microbial Risk Assessment (QMRA). QMRA has been widely used as an alternative method for epidemiological assessment of human exposure to microorganisms that can cause diseases, through a four-step process: (i) hazard identification, (ii) exposure assessment, (iii) dose-response assessment, and (iv) risk characterization. The results presented drinking as the water use with the highest risk, with 3.4 x 10-04 DALY per person per year, and, in decreasing order: bathing, food washing, hose irrigation and toilet flushing, with values for median risk of 6.5 x 10-07, 4.0 x 10-07, 2.1 x 10-07 and 1.4 x 10-07 DALY, respectively. Therefore, drinking would be the only water use that would require preliminary treatment for its safe use, considering the acceptable risk standards set by the World Health Organization. When associated with the use of simple protection barriers, such as clay filters and first flush devices, it was observed that would be possible to achieve even safer values, reaching 2 x 10-06 for intentional rainwater intake, which would already be close to the limit imposed as safe, confirming the efficiency of these measures.

  • Open access
  • 20 Reads
Rainwater Harvesting in Buildings in Brazil: A Literature Review

The rainwater use in buildings provides a number of benefits, such as securing water supply, resilience to climate change, reducing runoff in cities and potable water savings. This article presents a literature review about the use of rainwater in Brazil. A state of the art theme was presented focusing on economic, environmental and social impacts. The legislation related to rainwater harvesting ‒ including the cities that have made such a practice mandatory ‒ was also assessed. The potential for water savings is directly related to the amount of precipitation, and inversely to the potable water demand. Despite the variation in the availability of water in the country and the differences between the design and the use of the projected systems, it was concluded that there is a high potential for potable water saving when using rainwater in buildings in Brazil. The systems are efficient to supply the rainwater demands, both quantitatively and qualitatively. Some new topics are suggested, such as the study of the benefits and impacts of the large-scale rainwater harvesting use, the study of new methodologies and the effects on the drainage systems. Finally, the need for financial investments in experimental research and innovative technologies was apparent, in order to improve rainwater management, depending on user needs and environmental impacts.

  • Open access
  • 9 Reads
Identification of phytoplankton blooms under the index of Inherent Optical Properties (IOP index)

Phytoplankton blooms are sporadic events in time and isolated in space. This complex phenomenon is produced by a variety of both natural and anthropogenic causes. Early detection of this phenomenon, as well as the classification of a water body under conditions of bloom or non-bloom, remains an unresolved problem. This research proposes the use of Inherent Optical Properties (IOP) in optically complex waters to detect the bloom or non-bloom state of the phytoplankton community, as well as it is an active or a decaying bloom. An IOP index is calculated from the absorption coefficients of the colored dissolved organic matter (CDOM), the phytoplankton (φ) and the detritus (d), using the wavelength (λ) 443 nm. The effectiveness of this index is tested in five bloom events in different places and with different characteristics: 1. Dzilam de Bravo (Caribbean Sea, Atlantic Ocean, Mexico) a diatom bloom (Rhizosolenia cf hebetata), 2. Holbox (Caribbean Sea, Atlantic Ocean, Mexico) a mixed bloom of dinoflagellates (Scrippsiella sp.) and diatoms (Chaetoceros sp.), 3. Campeche in the Gulf of Mexico (Atlantic Ocean, Mexico) a bloom of dinoflagellates (Karenia brevis), 4. Upper Gulf of California (Pacific Ocean) a diatoms bloom (species to be determined) and 5. Ensenada (Pacific Ocean) a dinoflagellate bloom (species to be determined). The results show that the use of the IOP index is a suitable method to determine the bloom conditions in coastal stations.

  • Open access
  • 15 Reads
Sonochemical formation of hydrogen peroxide

This work detailed in this study utilized 20 kHz ultrasonic irradiation as a mechanism of hydrogen peroxide production. The effects of various operating parameters were investigated, including ultrasonic intensity, solution pH, source of water, initial dibutyl phthalate concentration and the presence of hydrogen peroxide. During the irradiation, the H2O2 concentration arising was monitored. The results indicate that H2O2 is produced by cavitation during ultrasonic irradiation. An increase in ultrasonic intensity increases the amount of hydrogen peroxide produced. The initial pH of the solution does not affect the efficiency of processes substantially. H2O2 is regarded as one of the most effective additives enhancing the sonochemical production of hydroxyl radicals and hydrogen peroxide, but too high a dose is known to exert a negative effect. Above a 0.1 mM dose of H2O2, the amount of H2O2 formed decreased as the concentration of H2O2 increased. Thus, the concentration of hydrogen peroxide plays a crucial role in the extent to which effectiveness of the combined process is enhanced. The negative effect on reactions of the presence of additional components in the reaction solution was also confirmed. It was therefore concluded that experimental evaluation of optimum parameters of hybrid processes is a matter of importance.

 

  • Open access
  • 17 Reads
Simulation of river water quality from in-situ data and satellite imagery, focus on organic pollutants

Water is an essential ingredient of life. Currently, this natural resource has been under pressure from the socio-economic development. This paper presents the application of remote sensing technology to monitor organic pollutants in water from Hoa An bridge to the confluence of the Saigon and Dong Nai River. The river water indicator was surveyed as Dissolved Oxygen (DO) and was calculated via spectral channels of Landsat 8 at the time of January 21, 2014. Research methods was approached in the direction of: Qualitative simulation from the spectral characteristics, and quantitative simulation based on regression analysis. The results showed that the concentration of the observed indicator DO had a linear correlation with the ratio based on green band B3 and red band B4 of Landsat 8 image. From the regression, this study established the spatial distribution maps to simulate organic pollutants in rive water of the studied area. The classification system was built according to the standards of QCVN08:2008/BTNMT. The study results shows that the application of remote sensing monitoring river water quality is a good support tool for environmental management purposes, to help policy-makers to see and have better decisions for the local socio-economic development.

  • Open access
  • 12 Reads
Risk of climate change impacting on drought and forest fire based on the spatial analysis and satellite data

Drought is considered a serious disaster after floods and typhoons and is tending to increase frequency and intensity due to climate change on a global scale. In addition, droughts also cause large and small fires that occur daily around the world, damaging the forest, the forest ecosystem and having a significant impact on the economy, society and people. This paper presents the situation of forest fires in U Minh Ha forest of Ca Mau province, which is the last land area in the south of Vietnam. The study used satellite imagery processing, which combined spatial analysis to identify areas of fire sensitivity, in the face of drought risk associated with climate change in the dry season in 2016. AHP hierarchy analysis was performed using factors such as surface temperature, leaf moisture, vegetation cover, vegetation density, distance to water sources, distance to residential areas and the distance to the fire protection works. The results show that in the study area, the zone with high fire sensitivity accounts for nearly half of the forest area and is distributed in the southwest. Study results are useful for planning strategies to protect forest resources against the drought risk caused by climate change that is increasing now.

  • Open access
  • 15 Reads
Photocatalytic oxidation of perchloroethylene by TiO2 coated on glass-bead

Chlorinated volatile organic compounds (VOCs), such as perchloroethylene (PCE), are widely used as industrial solvents in the dry cleaning, degreasing of metals, and plastics industries. As a result, these compounds are widely introduced into the air and water and contaminate them. Due to the toxicity and high volatility of these compounds and because they are suspected of being carcinogenic to humans and are extremely stable in the environment, their removal from water or air seems essential.

Photocatalytic oxidation is a special form of advanced oxidation, often used as a semiconductor solid, such as TiO2 and ultraviolet (UV) to activate it. Basically, the reactions that are catalyzed by TiO2 are also performed with other semiconductor photocatalytic agents. However, some of these photocatalytic agents are self-indulging and inactivated, are readily available or are susceptible to conventional organic and inorganic solvents. But the use of TiO2 has been very interesting due to its unique properties.

In this study, the photocatalytic removal of perchloroethylene was investigated by a filled glass-bead reactor. Also, the effect of relative humidity, residence time, concentration and ultraviolet light on the photocatalytic removal process was investigated.

In this study, the photocatalytic effect of ultraviolet light and photocatalyst TiO2 was compared, with reaction conditions, 1 min, 3000 ppm concentration and relative humidity of 30%, and the photocatalyst TiO2 had a higher removal capacity than ultraviolet light.

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