RCAAP Repository

Abstract The semiarid region of Pernambuco has a large water deficit, leading the population to explore groundwater resources such as alluvial aquifers. The state of Pernambuco also stands out for having the second-largest textile manufacturing center in Brazil. However, the direct discharge of textile effluents from the region's industries has intensified the negative impacts on water conservation and alluvial soils. This work characterized the sorption of Direct Black 22 dye (DB22) in two layers of alluvial soil in the Capibaribe-PE basin. Batch experiments (kinetics and sorption isotherms) allowed the evaluation of the retention potential and mobility of this compound in this environment. Sorption kinetics were verified for stirring times of 0.25; 0.5; 1; 2; 4; 6; 8; 10; 12; 24; 48 and 72 hours and the experimental data was adjusted to the first- and second-order kinetic models. The isotherm occurred with concentrations of 1; 5; 10; 15; 20; 32.5 and 40 mg.L-1 and experimental data was adjusted to the linear, Freundlich and Langmuir models. The sorption kinetics of DB22 was best described by the second-order model, while the Freundlich and Linear models properly fitted sorption isotherms for Layers 1 and 2. The organic matter contents and the cation-exchange capacity of the soil layers influenced the sorption of the dye. The superficial layer privileges dye retention phenomena, while in the subsurface layer dye mobility phenomena prevail.

Abstract Water erosion is the principal degradation process of tropical soils, and its effects can be measured by modeling techniques. Erosion models provide a diagnosis of the soil loss intensity and can support the planning of soil conservation practices. Models with low data requirements, such as the Revised Universal Soil Loss Equation (RUSLE) and, more recently, the Erosion Potential Method (EPM), are mainly applied in Brazil. Thus, the objective of this work was to estimate water erosion soil-loss rates using the EPM and RUSLE models on a tropical subbasin, followed by a comparison of their outcomes. The models’ application considered soil physical parameters, edaphoclimatic conditions of the area, land use, and subbasin management practices. The accuracy of the methods was verified using total transported sediment and water discharge data. We compared the models using Pearson's correlation analyses, considering a 5% of significance. We found a predominance of moderate-intensity erosion with average soil loss of 1.17 and 1.46 Mg ha-1 year-1, measured by EPM and RUSLE, respectively. The EPM model underestimated soil losses by 15.27%, and RUSLE overestimated by 19.08%, indicating a higher percentage of areas with high erosion rates (4.60%). The models presented results with a different order of magnitude, but with significant correlations, indicating that both methods pointed out similar zones of intense and light-erosion rates.

Abstract Plastic is a useful material; but along with its benefits also come several disadvantages. One of these is the consequences of the improper discarding of plastic in the environment and its eventual fragmentation into microplastics. Plastic can reach rivers and affect their biota as microparticles from its degradation. The entry of plastic into the food chain occurs by the consumption of fish or other organisms. Furthermore, persistent organic pollutants can accumulate, and the consumption of materials containing plastic pollutants can cause several physiological problems in animals. Such pollutants can reach man when water or fish is consumed. There are numerous studies in the marine environment that show that microplastics significantly interfere with marine biota; but there are relatively few studies addressing this topic in freshwater environments. This work characterized the diet of the most abundant fish species in an urban river of the Upper Paraná Brazil Watershed, investigating the occurrence of microplastic. As much as the studied river suffers from urban river syndrome, a wide variety of food consumed by fish was found. The stomach content of 220 individuals belonging to fourteen species was analyzed. In the stomach content analysis, 16 types of food items were found, most of them autochthonous. The species analyzed were grouped into four trophic categories, with iliophage as dominant one. The presence of microplastics was found in 2% of the studied individuals, two individuals of the species Rhamdia quelen, one specimen of Hoplosternum littorale and one specimen of Astyanax fasciatus.

Abstract This study monitored a drip irrigation system with different hydraulic heads, using control charts. The study included 25 tests, and was conducted at the Experimental Nucleus of Agricultural Engineering of the State University of Western Paraná, located in the municipality of Cascavel, Paraná. The drip irrigation system was operated by gravity, and had four hydraulic heads (10, 11, 12 and 15 kPa). The uniformity of the system was determined based on uniformity distribution. Uniformity monitoring was performed using Shewhart and exponentially weighted moving-average (EWMA) control charts. An increase in the hydraulic head increased uniformity. The use of 12 and 15 kPa hydraulic heads yielded good performance, whereas 10 and 11 kPa yielded regular performance. The use of control charts proved to be efficient; the Shewhart control chart was more robust, whereas the EWMA control chart, which indicated trends and deviations not shown by Shewhart control charts, was more sensitive.

Abstract Poor quality water, such as sewage, has become an alternative to reduce the consumption of good quality water by irrigation, especially in arid and semi-arid regions; however, water rich in salts can be harmful to agricultural systems. This research evaluated the impacts of salinity of waters of different qualities on the development of the sunflower culture and on the soil. The research was developed in the area of the Environmental Studies Team (EEA/UEFS), and the experimental design used was completely randomized, consisting of four treatments: rain water (0.20 dS m-1), well water (1.50 dS m-1), cesspool effluent (3.50 dS m-1) and brackish water (5.00 dS m-1), with the irrigation manually done and the blade calculated based on daily evapotranspiration. Irrigation with effluent promoted a better development of the sunflower crop, and the increase in the salinity of the irrigation water in the other treatments promoted a decrease in the total fresh and dry phytomasses, plant height, stem diameter, number of leaves, leaf area, internal and external diameters of the capitula and in the consumption and efficiency of water use. The use of rainwater, well water and cesspool effluent proved to be suitable for irrigation of the sunflower crop; however, the latter sodified the soil, which would already be recommended for the application of treatments for soil recovery.

Abstract This study evaluates the rainwater harvesting system to determine the chemical quality of the water and allocate it for use. Samples were collected in the city of Rio de Janeiro at the points of Direct Precipitation (DP), First Flush (FF) and Reservoir (RR). The methodology involved carrying out an analysis of Ca, Cd, Cu, Na, Ni, Fe, K, Mg, Pb, Zn, conductivity, turbidity, pH and chloride. The R language was used for the principal component analysis, Pearson coefficient correlation, hierarchical cluster analysis, Tukey test and boxplot. The results show that when there is no interference from the catchment surface (DP), the rainwater has a low concentration of metals, although the first millimeters of rain have a concentration above what is permissible in the guidelines issued by the Ministry of Health (Ordinance n° 05/2017). The disposal system (FF) reduced the concentration of pollutants in the RR, but not enough to comply with legislation. It was noted that Ca, K and Na are the main metals found in rainwater. During the dry period, there were significant correlations between the physico-chemical and meteorological parameters. The high concentration of metals in the wet period suggests that rain assists the cleaning of the atmosphere and that most metals are present in the form of aerosols or fine particles suspended in the air. The findings reveal significant indications of acid rain and pre-treatment is recommended to ensure rainwater can be used safely for more mundane purposes.

Abstract Urbanization in river basins contributes to the anthropogenic eutrophication of their water bodies, leading to the proliferation of toxic algae such as cyanobacteria. There is a characteristic pattern of seasonality in algal blooms and cyanobacterial communities, although these algae may be present or even dominant for most of the year, causing practical problems associated with high cyanobacterial biomass and potential health threats. The increased concentration of toxins originating from these algae, cyanotoxins, in water-supply reservoirs puts the population at serious risk, since they are not removed by conventional treatment and filtration. This study analyzed possible associations between climate elements and cyanobacteria biomass in the Guarapiranga dam reservoir, located in the metropolitan region of São Paulo, Brazil. Meteorological variables were studied exclusively in relation to the cyanobacteria biomass, in order to perceive the influence of weather and climate in this complex system and to provide data for modeling future climate change scenarios. For this purpose, cyanobacteria count data were used for the period from 2010 to 2016, grouped by month, in addition to the atmospheric variables. The strongest correlation with the blooms was with Irradiation and Total Rainfall, explaining 30% of cases of the occurrence of cyanobacteria proliferation at the point of collection GU 101. Despite the notable influence of climatic seasonality on the algae blooms, this difference varies and is not homogeneous, depending on the location and the species studied.

Abstract The study assessed the trophic state of three lakes used as fish farms in the region of Junín-Peru, under different hydrological conditions. Surface water samples were collected from three points at each lake in 2018 during the rainy (March-April) and dry (June-July) seasons. Total phosphorus, turbidity, and chlorophyll-a (Chl-a) were measured. Trophic indexes (TSI Chl-a, and TSI TP) were also computed. The water trophic state categorization was performed by adapting and calculating the Trophic State Index (TSI). The TSI (TP) classified the three lakes in both seasons (rainy and dry) as mesotrophic (30 < TSI ≤ 60). Pomacocha and Tipicocha were classified as eutropic (60 < TSI ≤ 90) in the two seasons according to TSI (Chl a), while Tranca Grande was classified as mesotrophic (also two seasons). The results for TSI showed a predominance of eutrophic and mesotrophic conditions in all lakes used as fish farms.

Abstract This study evaluated the impact of fulvic acid and free amino acids on paclobutrazol soil residue, their absorption and effects on ‘Keitt’ mango grown in tropical semi-arid environmental conditions. The experiment was carried out from 2017 to 2018 simultaneously in two orchards with the same plants and management characteristics, located in Cabrobó, Pernambuco, Brazil. The experimental design was randomized blocks with four treatments, five replications and four plants per replication. The treatments consisted of paclobutrazol combinations with acid fulvic and free amino acids, as follows: Treatment 1: paclobutrazol + water (control); Treatment 2: paclobutrazol + fulvic acids; Treatment 3: paclobutrazol + free amino acids; and Treatment 4: paclobutrazol + fulvic acids + free amino acids. According to the results, the use of fulvic acids, free amino acids or both affects the paclobutrazol absorption by 'Keitt' mango. The addition of fulvic acid to the paclobutrazol improves the absorption of this molecule by the plant, with greater inhibition of vegetative growth of 'Keitt' mango and lower soil residues.

Abstract We investigated the application of economic instruments in the management of Brazilian water resources as mechanisms to stimulate the rational use of water and to recognise its economic value. We analysed water-charge scenarios at the national and international levels as a methodology to provide an economic estimate of environmental services related to water resources. Through bibliographical and documentary research, we identified the economic instruments applied to Brazilian water-resource management, describing the methodologies and values used Brazilian water charges and in some member states of the Organization for Economic Cooperation and Development. We identified how economic valuation methods of environmental resources could contribute to the improvement of water charges, considering the environmental services offered by a healthy river basin. In the Brazilian and the international scenarios, water charge methodologies include the volumetry of abstracted or consumed water, associating some elements that indicate the pollution level. The prices per cubic meter of water are still very low in all the scenarios. Environmental valuation techniques can be an essential tool for rethinking the methodologies and costs applied in water charges, increasing the potential of water’s rational use through economic instruments.

Abstract Surface reaeration coefficient (K2), which represents the transfer of oxygen at the air-water interface, is an important variable in aquatic ecosystems. K2 is influenced by several factors, including surfactants; furthermore, this coefficient is used in water-quality models, which requires its correct estimation. This study evaluated the effects of the surfactant Sodium Dodecyl Sulfate (SDS) on K2 in two different experimental systems. In a cylindrical reactor with a turbine-type mechanical stirrer, 15 reaeration experiments were carried out with SDS concentrations of 0.0; 0.25; 0.5; 1.0 and 1.5 mMol L-1 and stirrer rotation velocities of 25, 50 and 100 rpm. In a circular hydraulic channel, 8 reaeration experiments were carried out, in triplicate, with SDS concentrations of 0 and 1.5 mMol L-1 and agitation levels of Reynolds 4,500, 37,500; 49,200 and 54,000. In the reactor, regardless of the rotation velocity, the surfactant reduced K2 by 20%, due to a superficial film formation at the interface that made oxygen transfer difficult, due to a phenomenon known as “barrier effect”. In the channel, an approximate K2 reduction of 15% occurred at higher levels of water agitation. In the presence of surfactants, and at low levels of agitation, phenomena that increase K2 (i.e., Marangoni effect) may coexist with those that reduce K2 (i.e., barrier effect). We concluded that the presence of SDS in aquatic environments should be considered when estimating the surface reaeration coefficient, because this surfactant can contribute to uncertain K2 estimation.

Abstract The Taquari River is one of the most important tributaries of the Paraguay River, whose sediments are carried and deposited on the plain forming the largest alluvial fan in the world, known as Pantanal. In the floodplain, the course of the river has been modified by the sedimentation process, resulting in lakes with different degrees of connectivity with the river. This study assessed the influence of connectivity on the physical and chemical characteristics of water along a hydrological cycle in oxbow lakes of the Taquari River floodplain, in Mato Grosso do Sul, Brazil. Sampling was carried out monthly, from May 2005 to June 2006.The physical and chemical data of the water and the variables of river level and rainfall intensity were correlated by Principal Component Analysis (PCA). Limnological differences resulted from distinct degrees of connectivity between the oxbow lakes and the Taquari River. Variations in the dry and rainy seasons established a gradient that extends over a space-time continuum and generates greater environmental heterogeneity and, consequently, greater biodiversity. Thus we conclude that this mosaic of lakes and the surrounding landscape requires protection and preservation because of its importance for biodiversity conservation.

Abstract This study developed and evaluated an electronic irrigation system controlled by soil water matric potential. The controller uses tensiometers and pressure transducers as a reading mechanism, integrated with an Arduino microcontroller board that drives the solenoid valves and a 1/3 hp single-phase motor. Four electronic tensiometers were installed in plastic containers filled with 6 kg of Red-Yellow Latosol (RYL) with a clayey texture, and another four in plastic containers filled with 7 kg of Regolitic Neosol (RN) with a sandy texture. Irrigation automation components were activated autonomously at the critical potentials of -20, -25, -30, and -35 kPa for RYL, and -10, -15, -20, and -25 kPa for RN, with a 20% variation tolerance. The entire system is able to monitor and control irrigation based on soil water matric potential. Components were deactivated when the soil water potential reached the field capacity of each soil type. Irrigation automation performance was considered satisfactory, as it kept critical potentials within the pre-established thresholds in both soil types. Automation control was set for matric potentials between -10 kPa and -35 kPa in RYL, and between -5 kPa and -25 kPa in RN.

Abstract In the Armed Forces' campaign activities, large troops may be exposed to serious health risks even before war itself. In 2010, for example, the Brazilian Army sent nearly 2,000 men to join the United Nations peacekeeping mission in Haiti, which was experiencing a cholera epidemic. This work therefore investigated the water quality and sanitation of the various types of reservoirs used in four field-training activities of a Brazilian Army Unit located in the state of Rio de Janeiro. Physicochemical and microbiological analyses of the water were carried out, and visual inspections and swab samples were collected from the inner surface of these reservoirs for counting coliform bacteria and counting mesophilic aerobic microorganisms. Physicochemical and microbiological analyses of water from different types of reservoirs revealed a lack of conformity with American Public Health Association and Ordinance Number 518, of 03/25/04, of the Brazilian Ministry of Health . It was observed that 50% of the collective and individual reservoirs did not have the desirable minimum levels of Free Residual Chlorine. In addition, in 35.7% of the total collective and individual reservoirs evaluated there was growth of coliform group bacteria and in 28.57% of them the number of heterotrophic bacteria exceeded the maximum recommendation. According to the swabs performed on the inner surfaces, results of the total viable mesophilic aerobic counts were above the recommended levels in 78.57% of the total evaluated reservoirs. Besides that, in the Lyster bags of activities 1 and 2, there was growth of coliforms, or 14.28% of the total evaluated reservoirs. It was concluded that there were failures in the management of multiple barriers during storage and / or distribution, as well as in the maintenance of disinfection to prevent or eliminate microbial contamination, indicating the need for corrective measures.

Abstract The grape industrialization process produces large volumes of solid organic waste, with the grape bagasse being the main waste generated in the winemaking process. Anaerobic digestion can be used to treat and dispose of agro-industrial biomass waste. The objective of this study was to evaluate the effect of the inoculum/substrate ratio on the Biochemical Methane Potential (BMP) of grape marc. The experiment was performed in laboratory scale through a system of reactor bottles in batches, removing a set of triplicate flasks for sampling and analysis every 48 hours, with the test lasting 12 days. The reactors contained residue, inoculum and 20% of nutritive solution, maintaining 20% of headspace. The reactors were incubated in an incubator at a mesophilic temperature (35 ± 2°C) and shaken manually every 24 hours. Three different inoculum/substrate (I/S) ratios of 0.75, 1.5 and 3 were used to evaluate the methane yield, organic removals and at the end of degradation the morphology of the bacterial community was evaluated by means of scanning electron microscopy. The I/S 3 ratio provided the best results for loading anaerobic systems, indicating that grape marc presents potential for biological treatment through anaerobic digestion.

Abstract The safety of a dam is the result of a series of factors, including structural, geotechnical, hydraulic, operational and environmental aspects. In Brazil, Law No. 12.334 of September 2010 establishes the National Dam Safety Policy, which requires safety reports and monitoring inspections for existing dams. The inspection comprises a set of devices installed on the dam, which are used to assess the structural behavior based on performance parameters of the structure, such as displacements, flows, stresses, slopes and others. Dam auscultation procedures, historically, have been performed since the 1950s. Since then, there have been significant advances in instrumentation and dam auscultation methods. This work presents a theoretical approach on technical and scientific aspects of dams in Brazil, based on a state-of-the-art literature review, involving auscultation of dams in the context of design codes, concepts, instrumentation, safety, procedures and monitoring methods.

Abstract The objective of this study was to evaluate the efficiency of dissolved ozone flotation (DOF) in comparison to dissolved air flotation (DAF) for treatment of milk industry wastewater (MW). In the first phase of the experiment, a synthetic milk wastewater (SMW) was used to evaluate DOF and DAF, with and without addition of hydrogen peroxide, at pH 4.0 and pH 11.4. In the DOF tests, the concentration of ozone was equal to 19 (± 0.5) mg L-1 and in the tests with addition of hydrogen peroxide, the H2O2/O3 ratios tested were 0.5, 1.0 and 1.5. In the second phase, tests were performed using three MW from three different industries to validate the results obtained and to determine the DOF system's ability to treat this type of effluent. The parameters tested during validation were turbidity, total suspended solids, oils and greases (O&G), chemical oxygen demand (COD), biochemical oxygen demand (BOD), total nitrogen (TN) and total phosphorus (TP). It was observed that the efficiency of the treatments was better at pH 4.0. The results showed a reduction of the efficiency with the use of DOF. The addition of H2O2 in DAF and DOF also resulted in reduced system efficiency. The results obtained with SMW only approximated those obtained with the MW from one of the industries that contained the largest traces of milk and cheese.

Abstract Flash floods are observed in the Una River Basin, Pernambuco/Brazil. This particular type of flood is a short-duration hydrological event with occurrence of the peak flow within minutes to few hours after the onset of the rainfall, taking place typically in mountainous regions. The objective of the paper was to assess the sub-daily hydrological and hydrodynamic modeling of flood events in 2011 and 2017. Sub-daily precipitation and streamflow were applied to the models Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) and River Analysis System (HEC-RAS). Model evaluation methods such as Nash-Sutcliffe efficiency (NSE), percent bias, and the ratio of the root mean squared error to the standard deviation of measured data (RSR) were used in the calibration process. The maximum infiltration rate and the Snyder peak coefficient estimation were the most sensitive parameters in the hydrological model. The calibration of the HEC-HMS showed good performances (Catende station NSE=0.78 and RSR=0.46; Palmares station NSE=0.68 and RSR=0.57). During HEC-RAS 1D flow simulations, steep regions in the Una River caused numerical instabilities. The 2D solution was needed to overcome this problem, allowing us to represent the water level in the city of Palmares satisfactorily.

Abstract Studies determining physiological characteristics of field-grown pineapples irrigated with low-quality water are lacking. This work evaluated the photochemical efficiency of ‘Pérola’ pineapple irrigated with saline water in the semiarid region of Bahia, Brazil. The experiment was carried out in randomized blocks with five treatments consisting of the following irrigation depths: 100% of ETc using water with electrical conductivity (ECw) of 0.75 dS m-1; and 50, 75, 100 and 125% of ETc using water with ECw of 3.6 dS m-1. Chlorophyll a fluorescence measurements were made over the course of 13 months using a pulse-modulated fluorometer, in all treatments. Quantum efficiency (Fv/Fm) fluctuated throughout the cycle of the pineapple with values below the ideal, especially at the end of the crop cycle. Quantum yield of photosystem II (Yield), photochemical quenching (qP), non-photochemical quenching (NPQ) and chlorophyll fluorescence decrease ratio (RFd) were not influenced by irrigation depths. Therefore, energy used for photosynthetic processes in pineapple plants is not affected by irrigation using saline water with electrical conductivity of 3.6 dS m-1.

Abstract Rural communities usually are poorly covered by basic services, including water supply services (WSSs). Within this context, community management of water is a promising alternative to address this issue, with many successes all over the world. This approach also contributes to the achievement of Sustainable Development Goal (SDG) 6, which intends to universalize water access. This paper evaluates the WSSs provided by eleven rural community organizations from Espírito Santo, Brazil. All of those participate in the sanitation program “Pró-Rural” created by Cesan (Companhia Espiritosantense de Saneamento), the state water concessionaire, to reach small-sized rural settlements. For this purpose, Siasar was used, an informational tool that enables the identification of elements in the rural water supply systems (RWSSs) that can enhance or hinder their performance. The results verified that the communities were able to maintain a satisfactory level of quality of the WSSs, although there were perceptible fragilities regarding the distance between internal (communities and service providers) and external (technical assistance providers) actors that can decrease the quality of the WSS or even lead to its interruption if not addressed.