RCAAP Repository

Abstract Hydrological behavior in reforested watersheds is different from that under other forms of cover. The variation may be related to aspects intrinsic to species, planting density, physiological maturity, management system and climatic conditions. Periodically, climatic anomalies such as the case of La Ninã are observed, and these are responsible for the alteration of the rainfall regime and consequently generate water deficits in the southern region of Brazil. Water deficit is responsible for reducing growth and productivity for the Eucalyptus genus, in addition to causing changes in hydrological behavior in reforested watersheds. Accordingly, this study compared the partition of rainfall in throughfall, stemflow and canopy interception of eucalyptus trees submitted or not to partial exclusion of precipitation. In the open field, 3 rainfall collectors were installed, and in the stand, for each rain exclusion treatment, 9 throughfall collectors and 9 stemflow collectors were installed. Every two weeks for 12 months, the volume of the collectors was measured. The quantified precipitation was 1627 mm over a year. In the treatment without exclusion, 84.8, 2.9 and 12.3% referred to throughfall, stemflow and canopy interception, respectively, while in the treatment excluding rainfall 80.6, 2.3 and 17.2% referred to throughfall, stemflow and canopy interception. The regression adjustments for throughfall and stemflow showed satisfactory R2 coefficients.

Abstract Bioconcentration and bioaccumulation levels of lead, zinc, iron and arsenic in Scirpus californicus of the Paca and Tragadero Lagoons, Jauja, Peru, were evaluated. Water, sediment and Scirpus californicus samples were collected from each lagoon, which were transported to the laboratory for the analytical determination of lead, iron, zinc and arsenic, which was performed by atomic absorption spectrophotometry based on the methodology recommended by FAO. The results obtained reveal the current status of the quality of the aquatic environment of natural wetlands in the central region of Peru in terms of heavy metals and arsenic, which provide an important source of water for the populations of large cities in the central region of Peru. The presence of heavy metals and arsenic with great impact on the quality of these water bodies may be due to the pressure exerted by anthropogenic activities such as mining, agriculture, industrial and domestic wastewater. The sediments of Paca and Tragadero Lagoons showed high concentrations of Fe, exceeding international standards. Aquatic vegetation represented by Scirpus californicus in both lagoons bio accumulated mainly Zn, without exceeding international standards.

Abstract This study analyzed the occurrence of nuclear damage in the red blood cells of Gymnotus inaequilabiatus (Valenciennes, 1839), exposed in vivo to the herbicide glyphosate. The fish were distributed in four groups, namely: control (without addition of herbicide) and contaminated groups with application of 65 µg/L (concentration allowed by CONAMA Resolution), 1 mg/L (maximum limit recommended by the World Health Organization - WHO and Food and Agriculture Organization - FAO) and 5 mg/L (overdose, five times higher than that by WHO and FAO). For the analysis of cell damage, the method of Nuclear Erythrocytic Abnormalities (NEA) was used, containing 1000 cells for duplicate elimination. An increase in cell damage was observed for 144 hours (6-days) of exposure in all controls. Even under a small concentration, there was a clear effect on segmented, renal, lobed formation and mainly on the formation of micronuclei. The high damage was caused in the first 48 hours and reduced after 144 hours, where the fish can have the herbicidal effect blocked. Studies that analyze the mechanisms of action of glyphosate-based herbicides are essential to determine the risks caused by biota, since there is a great divergence on the maximum tolerable limits in water, which affect quality and integrity of these ecosystems.

Abstract This study investigated the adsorption capacity of the elements Chromium (Cr), Manganese (Mn) and Zinc (Zn) to marine algae Lithothamnium calcareum by means of adsorption kinetics and batch adsorption tests, with a view to the development of a simple technique for the treatment of effluents that have a high concentration of metal ions. The algae was sieved, washed and subjected to treatment. In the adsorption kinetics, 0.2 g of algae was weighed, an amount transferred to 125 mL Erlenmeyer flasks, to which was added 15 mL of solution with a concentration of 5 mg L-1 of the metal ion. The flasks were stirred at 60 rpm for 240 minutes. In batch adsorption, 0.2 g of algae was weighed, amount transferred to 125 mL Erlenmeyer flasks, to which was added 15 mL of solution with concentrations of 5, 10, 20, 50, 100, 250 e 500 mg L-1 of the metal ion. The flasks were stirred at 60 rpm for 24 hours. In the two tests, the supernatant solutions collected were centrifuged at 2000 rpm for 5 minutes and the equilibrium concentrations of metal ions were determined by atomic absorption spectrometry. It was found that, in 240 minutes of contact, the Lithothamnium calcareum removed 15.5% of Cr, 33.0% of Mn and 8.0% of Zn in solution; and that in 24 hours of contact, at a concentration of 5 mg L-1, it removed 0.4% of Cr, 52.5% of Mn and 92.6% of Zn; and, at a concentration of 500 mg L-1, it removed 20.0% of Cr, 22.6% of Mn and 40.8% of Zn. The results showed that the Lithothamnium calcareum submitted to thermochemical treatment presented potential for use in the adsorption of Cr, Mn and Zn.

Abstract The sludge generated at drinking water treatment plants (WTPs) is a high-moisture content residue, and therefore difficult to handle, transport, dispose of or recover. During the last decades, geotextile tubes have been successfully applied to reduce the residue volume, facilitate its handling and subsequent reuse. This study aimed to understand the factors that interfere in the filtration and dewatering efficiencies and to experimentally analyze the dewatering process of WTPs sludge, evaluating different test procedures and investigating the influence of the type and dosage of polymeric additives on dewatering performance. Geotextile cone dewatering tests and geotextile bag dewatering tests were performed, using four different woven geotextile samples and an aluminum sulfate WTP sludge sample. The results showed that the use of geotextile cone dewatering tests for geotextile selection and for additive selection and dosage was representative for the dewatering process intended, reflecting the results verified in the geotextile bag dewatering tests. Sludge chemical conditioning increased dewatering rate and solids retention during the tests’ early stages, but it did not result in a higher final solids content sludge cake.

Abstract The demand for food production brings with it the increase of effluent generation, which represents a great problem for slaughterhouses, since effluents contain higher organic load, requiring adequate treatment to decrease environmental impacts. This study examines an alternative to solve this problem: the application of electrocoagulation in the treatment of anaerobic slaughterhouse and packing plant effluents, as this promising technique is both compact and robust. The removal of color, COD and turbidity was analyzed, and the operational cost was calculated. To optimize the process, the CCRD (central composite rotatable design) methodology was used with two independent variables: electric current density and electrolysis time, obtaining a complete factorial of 2² with 4 axial points and 4 repetitions at the central point. The most expressive removals were: 87%, 80% and 76% for color, COD and turbidity, respectively, the lower operational cost obtained was 0.12 US$.m-3. The statistical analysis allowed obtaining valid mathematical models for color removal and cost and, through the analysis of desirability, it was found that for current density of 8 mA.cm-2 and time of 20 minutes it is possible to maximize color removal (84%) and minimize the cost (0.21 US$.m-3).

Abstract Precise, accurate knowledge of percolation is key to reliable determination of soil water balance and a crop’s water-use efficiency. This work evaluated an approach to estimate the amount of water percolated in the root zone using soil water content (SWC) data measured at different time intervals. The approach was based on the difference of soil water content within and below the effective root zone of banana plants at different time intervals. A drainage lysimeter was used to compare the measured and estimated percolation data. The approach was then used in a banana orchard under drip and micro sprinkler irrigation, with and without the use of mulch. The soil water storage in the banana’s root zone was evaluated within a two-dimensional soil profile with time domain reflectometry (TDR). Mean percolation measured in the lysimeters did not differ from the approach’s estimates using intervals between SWC readings equal to or longer than 6 h from the end of an irrigation event. Percolation estimates under drip and micro sprinkler irrigation in the field, with and without mulch, were consistent with those measured in the lysimeters, considering the 6-h interval of SWC measurements. Percolation was greater under the drip irrigation system with mulch. The amount of water percolated was not influenced by the presence of mulch under the micro sprinkler system.

Abstract Arsenic (As) is one of the most harmful chemical elements known to man and to the environment, mainly due its high toxicity and wide distribution; the content of this element within the soils is a genuine concern, thus making it paramount to know its natural contents in a regional context. The present study aimed to determine the natural Arsenic content in the A horizon of 31 soil profiles from the state of Santa Catarina, Brazil, which is useful in determining reference values, monitoring, remediation of contaminated areas, legal regulation and Brazilian laws. Soil samples were prepared following the USPEA 3051A SW-846 method and were previously chemically reduced from As(V) to AS(III) by using the BCR method. The determination was performed in an Inductively Coupled Plasma - Optical Emission Spectrometry - Hydride Generation (ICP-OES-HG at cold vapor). Results obtained from the soil groups reveal the materials of basaltic origins as the ones with more As content while those of sediment origins had lesser content. Evaluated soil profiles fit into the following descending order regarding their As content: Latossolos, according to EMBRAPA (Oxisols according to Soil Taxonomy) > Nitossolo (Ultisols, Oxisols (Kandic), Alfisols) > Chernossolos (---) = Cambissolo (Inceptisols) = Argissolo (Ultisols) > Neossolos (Entisols).

Abstract This study evaluated the use of hydrogel on the development of Rapanea ferruginea under water restriction through Vibrational Fourier Transform Infrared Spectroscopy (FTIR-UATR). Seedlings of approximately 30 cm height were transferred in pots with 3 L of soil. The group of seedlings was separated into 5 different triplicate treatments according to the amount of hydrogel, as follows: H1 (25%), H2 (20%), H3 (15%), H4 (10%) and S (control without hydrogel). The applied hydrogel was mixed homogeneously with the soil. All treatments were irrigated with 40 mL of water. FTIR spectra were obtained from fresh leaves collected during 13 months of monitoring. The correlation of the hydroxyl (water) band with the main biomolecules between treatments with the control was evaluated using the Mann-Whitney test (p<0.05). The biomolecule bands were subjected to principal component analysis (PCA) and hierarchical clustering analysis (HCA). The results indicate a significant correlation of the water band with the lipid, hemicellulose, cell wall and starch components in the species. The use of hydrogel resulted in a significant difference in the water absorption band in relation to the control group through the Mann-Whitney test and in biomolecules as the HCA and PCA analysis suggested. The best development was observed in groups H4 (10%), H2 (20%) and H3 (15%). The use of hydrogel positively influences the biomolecular development of the Rapanea ferruginea and monitoring is viable by FTIR.

Abstract Microplastics are plastic particles smaller than 5 mm found in the environment, which can cause health problems for aquatic organisms and humans, being classified as emerging pollutants. In Guatemala, Lake Amatitlán is one of the most polluted lakes as it receives discharges of wastewater, treated and untreated, as well as other waste from Guatemala City and other major urban populations. In a recent study, microplastics were found in sediments in Lake Amatitlán, so it was necessary to determine whether the lake's fish are affected by these pollutants, which can be harmful to their health. This research aimed to determine the microplastics in fish from Lake Amatitlán, for which 65 specimens of Nile tilapia (Oreochromis niloticus) were collected in October and December 2020, and January 2021. The collected fish were dissected in the laboratory, where the number and type of microplastics were analyzed in the digestive tract, after their separation by digestion and filtration. Lines or fibers were the most common type of microplastics, found in 63 specimens (96.9% of the analyzed specimens), ranging from 0 to 27 lines/fibers per individual. The frequency of other types of microplastics found were 0-3 fragments/individual, 0-2 films/individual, and 0-4 foams/individual, while microspheres were not found in any specimen. The presence of microplastics in tilapia from Lake Amatitlán is an indicator of contamination in the lake by pollutants that could affect the trophic network and represents a risk for the fish consumers, requiring the attention of environmental and health authorities.

Abstract This research evaluates the removal of nutrients by microalgae in different photoperiod cycles, combined with constructed wetland in the wastewater treatment plant of the University of Santa Cruz do Sul, RS, Brazil. The treatment used took place between July and December 2018 and consisted of the following steps: preliminary treatment, secondary treatment with an anaerobic reactor, microalgae tank (MT), sand filter and constructed wetland, using the macrophyte Chrysopogon zizanioides. In the microalgae tank, three light cycles were considered: 12h/12h, 24h and 18h/06h, whose lighting was powered by a white LED lamp of 9 Watts and 6000 Kelvin, regulated by a light controller. The results indicated that there were no significant differences (p>0.05) between the values of soluble phosphorus, ammoniacal nitrogen, COD and BOD for MT comparing the three photoperiod cycles (12h/12h, 24h and 18h/06h). However, the system setup removed 100% of total coliforms, E. coli and TSS in the three light cycles. Regarding the removal of nutrients and organic matter, the light cycle with the best performance was the 24-hour cycle, considering a removal of 67.6% for soluble phosphorus, 94.0% for ammoniacal nitrogen, 63.7% for COD and 42, 7% for BOD, at the end of the treatment process. These results demonstrate that the use of microalgae in combination with constructed wetland has greater efficiency in the removal of nutrients, mainly phosphorus and nitrogen, in addition to reducing physical-chemical parameters and eliminating effluent toxicity.

Abstract This study assessed the concentrations of metals in the Dourados and Brilhante Rivers, investigated the influence of landscape features surrounding these rivers on water quality, and evaluated the risks associated with metal contamination for aquatic biota and human health. Sampling was conducted at eighteen sites distributed along the rivers in June 2016. The concentrations of metals (Cu, Zn, Mn, Fe, Cr, Al and Co) in the water were analyzed by inductively coupled plasma optical emission spectroscopy. All the samples possessed Fe concentrations above the threshold value for aquatic biota (0.3 mg L-1). Moreover, land use and land cover assessment of the study area revealed extensive agriculture activity, particularly in areas surrounding the Dourados River headwaters. Fe bioavailability for both rivers indicated risks for aquatic biota and human health. Overall, the elevated Fe content in these rivers was attributed to anthropogenic activity in the vicinity of these water bodies and the soil characteristics of the area. Considering the importance of river basins, it is necessary to implement public policies for their conservation, especially those related to the cultivation of forests of native species and sustainable agricultural practices, in addition to improving the effluent treatment infrastructure, which is essential to minimize the adverse effects of contamination by chemical elements in water bodies.

Abstract River regularization plays an important role in socio economic development. However, it also modifies the natural flow system of the river and its biotic and abiotic characteristics, causing significant impacts on rivers. To evaluate the impacts on the macroinvertebrate community caused by dam construction on the Poxim-Açú River, metrics of composition and community structure of the macroinvertebrates were analyzed, as well as ecological and biological traits of the region. Macroinvertebrates were collected at three sites located downstream the dam, before (2013) and after (2015) dam construction. The water quality was classified as “good” to “excellent” according to the biotics indices. The alterations of the flow regime of the river after the dam construction influenced the macroinvertebrate communities, modifying their diversity, equitability, richness, and the number of individuals.

Abstract Considering the importance of the development of simplified technologies and social control in sanitation actions, this study investigated the use of laterite for phosphorus removal in synthetic effluents, through adsorption, as a low-cost alternative with the possibility of reusing the generated effluent, for communities where access to sanitation is limited. In the experimental design, the variables pH, contact time, granulometry and laterite dosage were used. Factorial planning was used for processing, for optimization and desirability. It was observed that the removal efficiency did not have significant interference in relation to the pH and contact-time variables. The kinetics of the batch experiments showed that the ideal contact time was 6.4 hours and pH of around 4. The adsorption capacity was plotted against equilibrium concentration for the Freundlich and Langmuir isotherms. The Langmuir isotherm was more suitable for phosphorus adsorption. The results show that laterite was effective in phosphorus adsorption in the order of removal of 87%, showing itself to be a potential adsorbent material.

Abstract This study evaluated the influence of combinations of nitrogen and potassium doses on the physiology and fruit production of West Indian cherry irrigated with waters of different salinities in the second year of cultivation. The experiment was conducted in the municipality of Pombal-PB, Brazil, in plastic containers adapted as lysimeters installed in the field, in a randomized block design, 5 x 4 factorial scheme corresponding to five levels of electrical conductivity of irrigation water (ECw): 0.3, 1.3, 2.3, 3.3 and 4.3 dS m-1, and four combinations of nitrogen and potassium fertilization: 70% N + 50% K2O; 100% N + 75% K2O; 130% N + 100% K2O and 160% N + 125% K2O of the dose recommended for West Indian cherry, with three replicates and one plant per plot. The cv. ‘Flor Branca’ was grafted on the cv. ‘Junco’, between 420 and 550 days after transplanting. Nitrogen and potassium combinations did not mitigate the deleterious effects of water salinity on the physiology and fruit formation of West Indian cherry. An increase in ECw intensifies the intercellular electrolyte leakage and reduces the water potential in the branch, chlorophyll content in the leaves, CO2 assimilation rate, equatorial and polar diameters as well as the mass of fruits. Fertilization of plants with 70% N + 50% of K2O, compared to the other fertilization combinations, causes less intercellular electrolyte leakage and promotes higher CO2 assimilation rates, higher chlorophyll content in leaves, and fruits of larger size and mass.

Abstract Detention devices are often used as alternative measures for stormwater control. The Envelope Curve Method is widely used in Brazil to estimate detention device volumes. This method estimates the storage volume based on inlet and outlet balance, where the inlet is obtained by the Rational Method and the outlet by orifice bottom discharge. Usually, the outlet flow is adopted as a constant and equivalent to the maximum allowed, and this procedure can cause reservoir undersizing. This paper evaluates detention control measures’ hydraulic behavior for the Envelope Curve Method and proposes the inclusion of an outflow adjustment coefficient (Cout), seeking to compensate for the adoption of constant outlet flow simplification. Values for this coefficient were estimated for several Brazilian state capitals, ranging from 0.62 up to 0.65. The undersizing hypothesis due to the adoption of constant outlet flow was confirmed, as the simulations showed the need for an increase between 8.4% to 16.8% in the device size. This undersizing may be compensated for by applying the outflow adjustment coefficient (Cout).

Abstract The Brazilian Cerrado biome is the largest and richest tropical savanna in the world and is among the 25 biodiversity hotspots identified worldwide. However, the lack of adequate hydrological monitoring in this region has led to problems in the management of water resources. In order to provide tools for the adequate management of water resources in the Brazilian Cerrado biome region, this paper develops the regionalization of maximum, mean and minimum streamflows in the Tocantins River Basin (287,405.5 km2), fully located in the Brazilian Cerrado biome. The streamflow records of 32 gauging stations in the Tocantins River Basin are examined using the Mann-Kendall test and the hydrological homogeneity non-parametric index-flood method. One homogeneous region was identified for the estimate of the streamflows Qltm (long-term mean streamflow), Q90% (streamflow with 90% of exceeding time), Q95% (streamflow with 95% of exceeding time) and Q7,10 (minimum annual streamflow over 7 days and return period of 10 years). Two homogeneous regions were identified for maximum annual streamflow estimation and the Generalized Extreme Value distribution is found to describe the distribution of maximus events appropriately within the both regions. Regional models were developed for each streamflow of each region and evaluated by cross-validation. These models can be used for the estimation of maximum, mean and minimum streamflows in ungauged basins within the Tocantins River Basin within the area boundaries identified. Therefore, the results provided in this paper are valuable tools for practicing water-resource managers in the Brazilian Cerrado biome.

Abstract Aquaculture plays an important role in providing protein-rich foods, meeting the growing demand for fish. However, aquaculture is a potentially polluting activity, especially with regard to water pollution, due to the improper disposal of wastewater from the production process. Aquaculture wastewater is rich in nutrients (ammonia, nitrate, nitrite and phosphorus) and organic matter, and is commonly discharged into the environment without proper treatment. This can cause a series of environmental impacts and aggravate the current water crisis. Due to the importance and need to reduce environmental impacts, plan the use of water resources and achieve an efficient and sustainable production process, many researchers have focused their studies on effluent treatment techniques designed to remove these nutrients. This article therefore presents an updated review of the main physicochemical and biological techniques used in the removal of nutrients, which can mitigate environmental problems arising from aquaculture activities and contribute to the sustainability of the activity.

Abstract Given that atmospheric deposition is the first source of nutrient input into forest ecosystems, and that the precipitation partition serves as a nutritional source mainly when there is an interaction with the forest canopy, the objective of the present study was to quantify the nutrients input into rainfall, throughfall and stemflow in Eucalyptus urophylla stands with partial exclusion (E) and without exclusion (WE) of throughfall. The experiment was conducted in the northeast of the state of Paraná-Brazil, in the municipality of Telêmaco Borba. The partial precipitation exclusion system (E) is formed by a system of gutters that conduct 30% of throughfall out of the experiment. The nutrient input in rainfall was 55.7 kg ha-1 yr-1, while the sum of throughfall and stemflow was 64.1 kg ha-1 yr-1 in treatment (WE) and 39.8 kg ha-1 yr-1 in treatment (E). Interaction with the canopy of the trees enriched the rainfall with nutrients, mainly the elements potassium and chlorine, due to leaching of the vegetal tissues. The reduction of the water treatment system in partial exclusion of precipitation (E) reduced representative nutrient input. Although stemflow represents on average only 2.6% of the water volume, it is responsible for 6.7% of the amount of nutrients in relation to precipitation. Therefore, stemflow cannot be neglected in the balance of nutrient cycling. With a rotation of 7 years, the application of significant amounts of fertilizers can be avoided, considering the inputs of 449 and 277 kg ha-1year-1.

Abstract In this study, the ecotechnology artificial floating islands (AFIs), colonized by Eichhornia crassipes, have been tested as a tool for water quality improvement of fishponds. The experiment was carried out in semi-intensive production during the grow-out period of Nile tilapia, comprising one production cycle. It was completely randomized with two treatments (with and without AFIs) and three replications. Temperature, dissolved oxygen, conductivity, pH, turbidity, total dissolved solids (TDS), transparency (Secchi) and concentrations of chlorophyll a (CL a), total nitrogen (TN), total ammonia nitrogen (TAN), total phosphorus (TP) and orthophosphate (PO4 3--P) were analyzed fortnightly in the fishponds. Two groups ordered based on environmental characteristics were formed by applying the Principal Component Analysis (70.68% of explicability). The fishponds with AFIs were assigned to higher values of Secchi and lower values of pH, turbidity, TDS and concentrations of nutrients. On the other hand, the fishponds without AFIs were assigned to the highest values of these variables, except for Secchi. In 30 days, the AFIs showed the lowest concentrations of TP and PO4 3--P, and for CL a, TN and TAN, the differences were recorded after 90 days. The use of AFIs has demonstrated potential to conserve water quality in fishponds, notably for biologically assimilable elements (PO4 3--P and TAN) and for those directly related to eutrophication (P and N). Artificial floating islands should be encouraged for small and medium-sized farmers as tool to improve water quality in fishponds. However, new AFIs coverage rates must be evaluated, as well as the control of hydraulic retention rates.