Showing papers in "Ambiente E Agua - An Interdisciplinary Journal of Applied Science in 2021"

Analysis of microbial community biodiversity in activated sludge from a petrochemical plant

Abstract: The active sludge process is one of the most-used techniques for the biodegradation of organic compounds present in effluents from an assortment of wastewaters. This study investigated the bacterial community structure of a petroleum industry’s activated sludge and its physical and chemical parameters using high-throughput sequencing. Samples were collected over one year: autumn 2015 (C1), winter 2015 (C2), spring 2015 (C3), and summer 2016 (C4). Total DNA was extracted, and the primers targeting the V4 region of the 16S rRNA gene were used for amplicon sequencing. The majority of the detected microorganisms were considered rare microbiota, presenting a relative abundance below 1% of the total sequences. All of the sequences were classified at the phylum level, and up to 55% of the ASVs (Amplicon Sequence Variants) were associated with known bacterial genera. Proteobacteria was the most abundant phylum in three seasons, while the phylum Armatimonadota dominated in one season. The genus Hyphomicrobium was the most abundant in autumn, winter and summer, and an ASV belonging to the family Fimbriimonadaceae was the most abundant in the spring. Canonical Correspondence Analysis showed that physicochemical parameters of SS, SD and TSS are correlated, as well as ammoniacal nitrogen. Sample C3 presented the highest values of COD, AN and solids (SS, SD and TSS). The highest COD, AN, and solids values are correlated to the high frequency of the phylum Armatimonadota in C3.

Physiological responses of inoculated and uninoculated peanuts under saline stress

Abstract: This work evaluated the effects of water salinity on the physiological indices in inoculated and non-inoculated peanut plants. The study was carried out in a protected environment at the seedling production unit (UPMA) at Campus das Auroras, at the University for International Integration of the Afro-Brazilian Lusophony (UNILAB), Redencao, Ceara. The experimental design used was in a completely randomized (CRD), with treatments in a factorial arrangement, 5x2, referring to the five salinity levels of the irrigation water - CEa: 0.5, 1.5, 3, 4.5, and 6.0 dSm -1 , and inoculated and non-inoculated plants with a mix of rhizobia SEMIA 630, lot 0810, and SEMIA 6144, lot 0312, from Bradyrhizobium sp., isolated, with four replications. Recommended fertilization was done for phosphorus (62.5 kg ha -1 of P) and potassium (50 kg ha -1 of K) to supply the nutritional needs of the plants. The nutritional effect caused by symbiosis with Bradyrhizobium sp. favored inoculated plants to present greater tolerance to salt stress. The availability of nitrogen collaborated to increase the efficiency of plant physiological mechanisms. Uninoculated plants, even with a higher amount of chlorophyll and CO 2 , were not efficient in the photosynthetic rate. Saline stress affected photosynthesis, transpiration, stomatal conductance, internal CO 2 concentration, water use efficiency, and chlorophyll; however, with less intensity when inoculated with Bradyrhizobium sp. The increase in salinity on irrigation water increased the leaf temperature.

Effects on circulation and water renewal due to the variations in the river flow and the wind in a Brazilian estuary lagoon complex

Abstract: The Mundau-Manguaba Estuary Lagoon Complex is located on the coast of Alagoas state in Northeastern Brazil, and consists of two shallow lagoons, Mundau and Manguaba, that form a system of choked lagoons which are connected to the Atlantic Ocean by a series of narrow channels with a single outlet which dynamically alters its position. This study uses the Hydrodynamic Environmental System, SisBaHiA® to investigate how variations in river discharge and wind influence hydrodynamic circulation, water renewal, salinity and temperature in the lagoons. The free surface positions, obtained by model, were compared with the free surface positions measured at two points of the complex, showing good agreement. The analyses were carried out for dry and wet seasons and extreme events with very high freshwater discharge. The channel system of the lagoons is an efficient filter in reducing tidal variability inside the lagoons. The tidal ranges in the Manguaba and Mundau Lagoons are 90% and 80% lower, respectively, as compared with the values in the open boundary. The residence time calculated varied between 11 and 365 days and between 2 and 180 days for the Manguaba and Mundau Lagoons, respectively, making it possible to identify possible stagnation areas. The results from the salt and heat transport model show a prolonged period with low salt concentrations and slow salinity recovery after the rainy season; the water temperature in the lagoons shows little spatial and temporal variation.

Payment for water-ecosystem services monitoring in Brazil.

Abstract: The reduction of tropical forests has generated a loss of ecosystem services across the globe. In Brazil, essential biomes related to water provision (such as the Atlantic Forest and Savanna) have been degraded, compromising water-ecosystem services. Payment for water-ecosystem services (water PES) has been implemented as a tool to stimulate changes in the use and management of these areas. Many water PES projects have emerged in Brazil using forest restoration, aiming to improve water ecosystem services. In this context, this study identified the types of monitoring carried out in Brazilian water PES projects, to include their main characteristics and gaps. Five Brazilian projects were selected for analysis as case studies. Interviews were then conducted with stakeholders to get current data on their monitoring practices. The data from the literature review, case study approach, and interviews were analyzed from the perspective of monitoring guides recommendations. Different aspects were analyzed, such as objectives, institutional arrangements, type of monitoring, indicators, and frequency of monitoring. The study indicates that there is a lack of standardized methods, making it difficult to specify the results of the implemented actions. The central gap is related to benefit monitoring. It is necessary to establish a holistic monitoring system, dealing with the ecosystem as a complex socio-ecological system. Some perspectives to solve the problems were proposed. The results of this work may help not only improve the current and future PES schemes in Brazil but also in other countries, especially developing ones, where vulnerable populations depend upon them.

The use of artificial feed in Haliotis squamata farming in submerged cage culture system at Lae-Lae island, Makassar

Abstract: This study investigated the use of a combined formula of artificial feed and fresh marine algae Gracilaria sp in a submerged cage culture system and its effect on Haliotis squamata relative growth and survival rates. The experiment was performed in Lae-Lae Island, Makassar from May to October 2016. The sample Abalone juvenile larvae were 1.5 cm in size and stocked at a density of 30 pcs/cage. The cage size was 30 cm x 15 cm x 7 cm and equipped with a 2-inch Paralone pipe. This experiment employed a completely random design (CRD) with 3 treatments and 3 replicates. The applied treatment included the combination of artificial feed and fresh marine algae Gracilaria sp. Each treatment included: A. 25% artificial feed + 75% fresh marine algae, B. 50% artificial feed + 50% fresh marine algae, C. 75% artificial feed + 25% fresh marine algae, and was given at the proportion of 20% of the abalone's weight. The results of the study indicated that the use of a combined artificial feed with fresh marine algae ( Gracilaria sp.) had no significant effect on relative growth and survival rates of Haliotis squamata. Although feed treatment did not significantly affect the relative growth and survival rate, descriptively, treatment A contributed to the most optimal relative growth and the survival rate compared to treatments B and C.

Analysis of fire risk in the Amazon: a systematic review

Abstract: Fires such as those that occurred in 2019 in the Amazon are examples of the intensification of these events in recent years and contradict the claim that forest fires only reach great proportions in years of extreme drought. This is a worrying scenario, as the Amazon Rainforest plays an important role in regional and global climate regulation. This study therefore sought to identify the methodologies used to describe and predict fire events in the Brazilian Amazon. For this, a systematic literature review was carried out in the open access databases Scientific Electronic Library Online (SciELO) and Directory of Open Access Journals (DOAJ) using the descriptors “fire risk” and “Amazon”, and their variants in the Portuguese language and the logical operator “AND” in the search. From the resulting search materia we identified the use of predictive models based on projections for climate change developed by the Intergovernmental Panel on Climate Change (IPCC), which indicate a substantial increase in the probability of fires. Another technique used is the crossing of heat foci data with the forms of land use, evidencing the areas that burn the most and when, as well as the most susceptible areas. There were also studies analyzing the performance of fire risk indexes, demonstrating those that could be used after adaptations to local characteristics. These results allow an understanding of the behavior of fire in the Amazon, since they provide a broad view of how studies on fires have been conducted and what techniques have been used.

Wastewater reuse in irrigation: short-term effect on soil carbon and nitrogen stocks in Brazilian semi-arid region

Abstract: The main process that opposes the Greenhouse Effect is called “carbon sequestration”, a phenomenon that essentially seeks to establish a dynamic balance between greenhouse gas (GHG) emissions from the immobilization of its elements, especially C and N This work evaluated the stocks of carbon and nitrogen in soils of the Brazilian semi-arid submitted to irrigation with treated wastewater from domestic sewage For this purpose, the carbon and nitrogen stocks in the soil of the semi-arid region of Brazil were compared for four different uses: Open Native Caatinga (ONC); Treated Wastewater Effluent Irrigation (TSEI); Surface Water Irrigation (SWI); and Traditional Rainfed Agriculture (TRA) The hypothesis considered in this research was that the application of treated effluents in agriculture, besides being an alternative that can mitigate the problem of water scarcity of the semiarid region, is also capable of influencing the storage capacity of C and N in the soil, due to its organic load The results indicate that among the different land uses evaluated, soil C and N stocks were highest in ONC, and decreased with the agricultural land use The greatest accumulation of C and N in Caatinga is due to the presence of forest litter, and the influence of irrigation with treated sewage effluent was not detected in the present study It can be concluded that the contribution of vegetation residues to the soil surface is the main factor contributing to C and N storage

Soil bioengineering in northeastern Brazil: An Overview

Abstract: This article presents an overview of the application of soil bioengineering techniques, also modeled as natural engineering, in the state of Sergipe, northeastern Brazil, showing the importance of integrating living and inert elements to protect river banks from erosion. The employed techniques are different, ranging from the characterization of susceptibility to erosion to the use of biotechniques, considering knowledge in the areas of agronomic engineering, forestry engineering, civil engineering, biology, pedology, geology, geomorphology and geotechnics. It is an approach that uses techniques and methodologies in a multidisciplinary way, seeking to maximize synergies (for example, natural engineering techniques to combine inert materials in ways that help plants to develop increasingly efficient systems). This approach also considers maintenance-cost optimization in the conduction of the works, using different materials, differing from traditional engineering, which uses predominantly inert materials. The research work carried out in different locations sought the availability of local materials such as rocks, geotextiles made from fibers from the native flora or even available on the market, in addition to the use of native species to recovery of the banks or slopes, according to the ecological conditions of the northeastern Brazil. Size and technological and ecological reach were also considered, in addition to different biotechnical aesthetic objectives adapted to different situations.

Assessing glyphosate concentrations in six reservoirs of Paraíba do Sul and Guandu River Basins in southeast Brazil

Abstract: Glyphosate is a popular herbicide used worldwide, and several studies consider it to be an environmental hazard affecting human health. The present study aimed to detect glyphosate in six different reservoirs of Paraiba do Sul and Guandu River Basins in Southeast Brazil, used for multiple purposes, including fishery activities and domestic water supply. Ion chromatography was used to analyze the water samples, as it is a fast and environmentally friendly technique to detect glyphosate. Our results revealed that, despite differences related to trophic state, season of the year or distance to urban areas, glyphosate was detected in all reservoirs and in three of them with concentrations above the limit imposed by Brazilian legislation. Among the environmental variables studied, turbidity presented the highest correlation with glyphosate concentrations. The effect of rainfall increasing turbidity in the rivers reinforces the importance of draining waters from surrounding areas that transport glyphosate into the aquatic ecosystems. The detection of the herbicide in the various systems confirms the wide use of this compound in the drainage basins of the studied reservoirs and highlights the importance of water monitoring. Further, the results reveal how urgent and important it is to explore through laboratory experiments the pathways of degradation of this herbicide in tropical and subtropical aquatic environments together with its effects on flora and fauna.

Stemflow and throughfall in agricultural crops: a synthesis

Abstract: The interception of rainwater in annual and perennial agriculture has been the object of several studies in the last decades. However, scant attention has been paid to where this research has taken place and which principal crops have been studied. The objective of this research is to perform a bibliometric analysis of one hundred articles from the last forty years found in the Scopus database to analyze their spatial distribution according to continent and country and quantify the research carried out on annual and perennial crops. Also, the main methods used to investigate the stemflow and throughfall of water in commercial crops are described. Our analysis indicates that the northern hemisphere has the most research on the subject and 35% of the research took place in Asia. Most of the research into annual crops (56%) was carried out in maize ( Zea mays L .). There has been a significant increase in commercial (annual) agricultural research in the last decade. The stemflow had the most amplitude between the values in the annual crops. This may be related to morphological and ecophysiological changes throughout the plant cycle. For perennial crops, stemflow values were like forests. It has become more important than ever to consider a scenario of global climate change stemflow and throughfall research in agricultural areas, or at least the data need to be revised in the face of new climatic conditions.

Occurrence of 17α-ethinylestradiol in Paranoá Lake watershed (Brasília, Brazil): sewage, freshwater and treated water

Abstract: Emerging contaminants such as 17α-ethynylestradiol (EE2) can be discharged from sewage systems and contaminate water supplies. Paranoa Lake is a strategic water reservoir in Brasilia (Brazil) that receives treated sewage from sewage treatment plants (STPs) and has recently become a water supply. This study monitored EE2 residues in different matrices from Paranoa Lake watershed using the ELISA method. This monitoring was performed together with the local environmental agency in two periods. EE2 was detected in all sewage samples showing that this residue is continually being discharged into the lake. However, EE2 was found in only one freshwater sample (0.07 ng L-1), which is below the predicted no-effect concentration considered as a risk for aquatic animals. EE2 was not detected in treated water. Nevertheless, the increased use of freshwater as a water supply signals the need for continuous EE2 monitoring in the lake.

Performance evaluation and coefficients of reliability for waste stabilization ponds in northeast Brazil

Abstract: This paper assesses the reliability of Waste Stabilization Ponds (WSP) and proposes an alternative approach to WSP design based on the calculation of coefficient of reliability (COR) from an acceptable measure of violation of discharge standards. For that, data were collected from 10 full-scale systems operating in Northeast Brazil. All systems receive predominantly domestic effluent and are composed of one facultative pond and two serial maturation ponds. Different levels of restriction for effluent discharge were considered regarding the parameters: BOD, COD, total suspended solids, ammonia and thermotolerant coliforms. The Log-normal Probability Distribution Function (PDF) was able to represent the behavior of the concentration data in the effluent and, therefore, allowed the COR calculation. The COR was obtained from the coefficient of variation (CV) of the concentrations and the standardized normal variable associated with a 95% probability of non-exceedance. The observed dispersion of the results proved to be detrimental to the adoption of a single COR value for the evaluated parameters. In addition, the comparison between observed and design/operational concentration for optimal performance showed that the 95% reliability scenario represents a less achievable target for WSP systems.

A hybrid approach associating flow network modeling with AHP-Entropy for simulating and ranking water-demand management alternatives

Abstract: In view of the water crises historically experienced by Brazil’s semi-arid region, it is necessary to search for methodological tools that allow us to propose efficient alternatives for managing water demand. In this regard, the present study developed and applied a hybrid approach of flow network modeling and the Analytic Hierarchy Process (AHP) combined with Shannon’s entropy for simulating and prioritizing water demand management alternatives in the Epitacio Pessoa Reservoir in the Brazilian semiarid region. The approach initially performed simulations of the hydro system flow network to explore rational alternatives that evaluated the following criteria: meet the demands of human supply, meet the demands for irrigation, maintain the reservoir above the target volume, and reduce consumption. Subsequently, Shannon's entropy was used to assess the importance of the criteria and the multicriteria analysis of ranking of alternatives was built. Finally, a sensitivity analysis of the model was performed regarding the dependence on respective weights of the criteria. The results made enabled evaluation of the hydro system’s water security, highlighting insufficient supply by the single measure of water management transposition of the Sao Francisco River, and based on the hierarchy of alternatives, suggesting actions to improve the sustainability of water use, such as reuse of water, reduction of losses in supply systems and increasing irrigation efficiency. The proposed hybrid approach permitted the synthesis of the simulation’s results, which may simplify and support the decision-making process in water-demand management.

Probability of rainfall for the city of Cruzeiro do Sul, Acre, Brazil

Abstract: Due to randomness in the occurrence of hydrological phenomena, the estimation of probable rain precipitation in a given region is important in assisting decision-making. This work aimed to adjust the probabilistic model of the Gamma distribution to the monthly and annual rainfall totals recorded in the city of Cruzeiro do Sul, Acre, for the period between 1970 and 2019, in addition to estimating the expected values at different probability levels. Using the maximum likelihood method, the distribution parameters were estimated, with adherence ratified by the Kolmogorov-Smirnov test. The results showed that the Gamma distribution was adequate to adjust the data; the region has two well-defined periods in its rainfall pattern; the mean precipitation values recorded in the locality are between 25% and 40% of probability. Finally, probable rainfall values were presented at different probability levels for the city of Cruzeiro do Sul.

Application of the SWAT hydrological model in flow and solid discharge simulation as a management tool of the Indaia River Basin, Alto São Francisco, Minas Gerais

Abstract: Measurement and evaluation of soil erosion and consequent sediment yield are fundamental in the planning and management of watersheds, as they allow the identification of critical areas susceptible to erosive processes. This study analyzed the sediment yield generated by water erosion in the Indaia River Basin, Alto Sao Francisco, Minas Gerais, by using the SWAT hydrological model. From a regional/local scale, the initial simulation of the variables (flow and solid discharge) was performed on a monthly scale from 1988 to 2017. Then, parameter-sensitivity analysis, calibration, and validation of the model were executed. In the monthly calibration (1988 to 2007), the performance of the simulations for flow was R 2 =0.92 and NSE=0.91 and for total solid discharge R 2 =0.51 and NSE=0.50. In the monthly validation (2008 to 2017) for flow, R 2 =0.85 and NSE=0.82 was obtained and for total solid discharge R 2 =0.19 and NSE=0.16. Despite the unsatisfactory result in the validation stage, the model was able to analyze the distribution of sediment production by sub-basins or even by the Hydrologic Response Unit (HRU). Therefore, a sediment-yield map was generated which qualitatively indicated a tendency for greater erosive processes in the central portion of the basin. The results will support public policies mitigating environmental degradation of the Indaia River Basin.

High iron content in river waters: environmental risks for aquatic biota and human health

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.

Adequacy of methodologies for determining SCS / CN in a watershed with characteristics of the Pampa biome

Abstract: The Soil Conservation Service Curve Number Model is a conceptual model intended for estimating effective rainfall (ER). This model is grounded in a parameter – referred to as Curve Number (CN), which is determined from information on the characteristics of the watershed. The Standard Method (M1) for determining the CN is based on soil and land-use tables; however, some authors have proposed alternative methodologies for defining the CN value from monitored rainfall-runoff events, such as those described by Hawkins (1993) (M2), Soulis and Valiantzas (2012) (M3), and Soulis and Valiantzas (2013) (M4). The objective of this study was to evaluate the impact of using these methods for determination of the CN parameter on the estimation of ER, taking as reference forty rainfall-runoff events monitored between 2015 and 2018 in the Cadeia River Watershed, which has characteristics of the Pampa biome. The different methods assessed for definition of the CN parameter resulted in contrasting performances with respect to the estimation of ER for CRW, as the following findings: i) M1 gave ER values with little reliability, mainly due to the classification of antecedent moisture content classes; ii) M3 provided the best results in determining ER, followed by M2; and iii) the ER values estimated according to M4 differed from those observed, mainly for events with lower rainfall depths.

Machine-learning methods for hydrological imputation data: analysis of the goodness of fit of the model in hydrographic systems of the Pacific - Ecuador

Abstract: Computational methods based on machine learning have had extensive development and application in hydrology, especially for modelling systems that do not have enough data. Within this problem, there are data series that are missing, and that should not necessarily be discarded; this is achieved by means of the imputation of the same ones, obtaining complete sets. For this reason, this research proposes a comparison of computer-learning techniques to identify those best suited for hydrographic systems of the Pacific of Ecuador. For the elaboration of this investigation, the hydro-meteorological records of the monitoring stations located in the watersheds of the Esmeraldas, Canar and Jubones Rivers were used for 22 years, between 1990 and 2012. The variables that were imputed were precipitation and flow. Automatic learning machines of the Python Scikit_Learn module were used; these modules integrate a wide range of automated learning algorithms, such as Linear Regression and Random Forest. Finally, results were obtained that led to a minimum useful mean square error for Random Forest as an automatic machine-learning imputation method that best fits the systems and data analyzed.

Comparative analysis between the chlorination and ultraviolet radiation methods for the disinfection of bacteria-contaminated water

Abstract: The quality of water for human consumption has been a concern for large organizations and researchers, since the disinfection process, a step of great importance in water treatment plants, has not achieved its proper purpose. There have been frequent reports of the ineffectiveness of bacteria inactivation by the use of chlorine, which is the most used in Brazil, and also due to the formation of by-products such as trihalomethanes and haloacetic acids that are considered toxic to human health. The method of disinfection by ultraviolet radiation (UV) has been widely explored, due to its effectiveness in inactivating a wide variety of pathogens, in addition to the absence of by-product formation. The combined chlorine+UV process as chemical and physical disinfectants, respectively, is complementary and essential when looking for the safety of water for human consumption. The objective of this research was to statistically analyze the performance of disinfectants, chlorine and UV radiation, both separately and together, by inactivating the bacteria Escherichia coli and Pseudomonas aeruginosa and then incubating for 48 hours after having received the treatments. The statistical method showed that chlorine and UV obtained the same significance of 100% bacteria inactivation, and that within the determined time of 48 hours after the treatments the bacteria did not show reactivation. Thus, the study affirmed the usefulness of applying UV radiation as a complement to systems that use chlorine, with a special focus on residential water systems and supply.

Evaluation of the environmental life cycle of an STP that employs a low-rate trickling filter as post-treatment of a UASB reactor and different sludge-management alternatives

Abstract: This study aimed to undertake an environmental life cycle assessment (LCA) of a sewage treatment plant (STP) equipped with low-rate trickling filters (TFs) as post-treatment of upflow anaerobic sludge blanket (UASB). The STP is located in South Brazil and uses landfill and agriculture as sludge-disposal alternatives. The evaluation was performed using the LCA technique and SimaPro® 9 software. The results revealed that the gases methane (CH 4 ) and sulfur dioxide (SO 2 ), emitted into the atmosphere after the partial burning of the biogas in flares, are mainly responsible for impacts in the categories of global warming (GW) and terrestrial acidification (TA), respectively. Due to the low rate of hydraulic sewage application in TFs, nitrous oxide (N 2 O) emissions stood out due to their high impact in the category of stratospheric ozone depletion (SOD). The use of sludge in agriculture obtained a greater potential for environmental impact compared to landfills in five of the eight categories evaluated. The main impacts of agricultural use were in the category of human toxicity (HT), due to the high concentration of zinc present in the sludge, and in the category TA, due to the emission of ammonia (NH 3 ) during hygienization of the sludge. In turn, the main positive aspects were avoided products, such as urea, phosphate fertilizer and limestone. The results contribute to a greater discussion of sewage-treatment processes, as well as sludge-management alternatives used in developing countries.

Soil attributes as indicators of the stabilization process of erosion in gullies at different formation stages in the southeast region of Brazil

Abstract: Water erosion is one of the main forms of soil degradation, causing economic, environmental, and social damage. This study evaluated the effects of different formation stages of gullies (initial - IG; juvenile- JG; mature - MG; and senile - SG) on the chemical, organic carbon and microbiological attributes of soil, using a secondary forest (SF) and two areas of pasture as references in the “Mar de Morros” environment of the Brazilian Atlantic Forest biome. Soil samples (depth 0–0.05 m) were collected at the end of the rainy and dry seasons. Gullies in different stages of formation promote a decrease in soil fertility and modification of microbiological attributes, particularly when compared with secondary forest areas. Reductions of over 60% in total organic carbon (TOC), oxidizable organic carbon (POXC), FDA activity, β-glycosidase, acid phosphatase, C and N from microbial biomass, basal soil respiration (BSR) and glomalin-related soil protein (GRSP) were observed in gullies in early (IG) and intermediate (JG and MG) stages when compared to SF. It was found that the effect of erosion on soil chemical and microbiological attributes is more intense in gullies in the initial and intermediate stages compared with those in the senile stage (SG). Using multivariate PCA, the microbiological and chemical attributes of the soil are discriminated between gullies with distinct formation stages. Chemical attributes, TOC, POXC, FDA activity, β -glycosidase, acid phosphatase, MBC and MBN, BSR, and GRSP are good indicators for evaluating the process of erosion stabilization in gullies.

Impact of climate change on monthly streamflow in the Verde River Basin using two hydrological models

Abstract: This study assessed the impact of climate change on monthly streamflow in the Verde River Basin, located in the Grande River Basin headwater. For this purpose, the SWAT and VIC hydrological models were used to simulate the monthly streamflow under RCP4.5 and RCP8.5 scenarios, obtained by Regional Climate Models Eta-HadGEM2-ES, Eta-CanESM2 and Eta-MIROC5 in the baseline period (1961-2005) and three time-slice (2011-2040, 2041-2070, and 2071-2099) inputs. At the end of the century, the Eta-HadGEM2-ES showed larger decrease of precipitation in both radiative scenarios, with an annual reduction of 17.4 (RCP4.5) and 32.3% (RCP8.5), while the Eta-CanESM2 indicated major warming, with an annual increase of 4.7 and 10.2°C under RCP4.5 and RCP8.5, respectively. As well as precipitation changes, the Eta-HadGEM2-ES also showed greater impacts on streamflow under RCP4.5 for the first time-slice (2011-2040), with an annual decrease of 58.0% for both hydrological models, and for the RCP8.5 scenario by the end the century (2071-2099), with an annual reduction of 54.0 (VIC model) and 56.8% (SWAT model). Regarding monthly streamflow, the Eta-HadGEM2-ES and Eta-CanESM2 inputs indicated decrease under the RCP8.5 scenario by the end the century, varying from 7.2 to 66.3 % (VIC model) and 37.0 to 64.7% (SWAT model). In general, Eta-MIROC5 presented the opposite in terms of direction in the simulations with both hydrological models at the end of the century. Combined effects of climate models, hydrological model structures and scenarios of climate change should be considered in assessments of uncertainties of climate change impacts.

Use of natural mucilage extracted from the Stenocereus griseus (Cardón Guajiro) plant as a coagulant in the treatment of domestic wastewater

Abstract: Coagulants can be extracted from vegetal material and applied in the treatment of wastewater. These coagulants are derived from seeds, leaves, bark, roots and fruits. This study focuses on the use of the mucilaginous extract of Stenocereus griseus (known as Cardon Guajiro) for removal of biochemical oxygen demand (BOD 5 ), chemical oxygen demand (COD), total solids, turbidity and color in domestic wastewater from a pumping station in the city of Cartagena (Colombia). The optimal dose of S. griseus extract was determined by a pitcher test employing an E&Q F6-300 digital flocculator. All physicochemical tests were carried out following the specifications of the standard methods for wastewater (APHA). When 1400 mgL -1 of natural coagulants were used in the sewage treatment, the turbidity obtained was 29.57 TNU, representing removal of 67.24%, considering the initial turbidity. This parameter decreases until 68.61 PCU, for a 72.12% removal at the same coagulant dosage regarding the color. It must be noted that significant statistical differences were found between all tested doses of the coagulant. The mucilaginous extract of S. griseus exhibited useful properties in the primary treatment of domestic wastewater.

Sorption studies of Cd and Cu on Brazilian alluvial soils

Abstract: The Local Production Arrangement, located in the Pernambuco’s Agreste state, has been significantly developing the region's economy. Despite its importance, industrial activity has caused relevant environmental concerns regarding the disposal of textile effluents, especially from industrial laundries. This waste is made up of many chemicals, and among them are various types of heavy metals. The evaluation of the sorption behavior of contaminant transport mechanisms such as heavy metals is essential to assess the risk of contamination of alluvial aquifers. This study evaluated the sorption of heavy metals (Cu and Cd) in an alluvial sediment deposit in the Capibaribe River. Kinetics and isotherm experiments allowed the analyses of Cu and Cd sorption. Kinetics sorption showed an equilibrium tendency after 16 h for Cu and 18 h for Cd and was better described by a pseudo-second order model. The isotherm data were adjusted to the Linear, Freundlich and Langmuir models. Both linear and Freundlich models satisfactorily described sorption isotherms for the two pollutants. The metals in the study represent a risk of contamination of the groundwater of alluvial aquifers, mainly due to physicochemical attributes of the soil, such as high sand content (85%), low MO (2.1 g kg-1) and alkaline pH (8.2). The environmental conditions decrease absorption and facilitate metal mobility, greatly increasing the environmental risks inherent in pollutant leaching. Cu showed a higher affinity with the soil studied in all assays performed compared with the results of the tests for Cd.

Hydrological modeling in a basin of the Brazilian Cerrado biome

Abstract: The Brazilian Cerrado biome (BCB) is among 25 biodiversity hotspots identified worldwide, and covers the recharge area of important aquifers and rivers in South America. The increase in deforestation has been threatening water availability in this region. In order to assist in the water-resource management of the BCB, this study models the daily streamflow in a basin of the Cerrado, using two approaches: a process-based model (Soil and Water Assessment Tool - SWAT) and the data-driven model (Artificial Neural Network - ANN). The performance of the models was evaluated by the Nash-Sutcliffe coefficient (NSE), coefficient of determination (R2) and flow-duration-curves (FDC). The results indicate that SWAT (NSE > 0.61; R2 > 0.68) and ANN (NSE > 0.91; R2 > 0.79) models are suitable tools in daily streamflow modeling of the studied basin, with the ANN model being the most accurate. Based on FDC, the ANN model was also better than the SWAT model for all frequencies evaluated. Thus, the ANN model is a promising new approach for daily streamflow modelling in this region. Moreover, the results of this study can help water-resource managers in planning and implementing appropriate water allocation and conservation measures in the Brazilian Cerrado biome.

Surveillance of public water supply fluoridation and municipal indicators: an analysis in the state of Espirito Santo, Brazil

Abstract: This study investigated the demographic, socioeconomic, and municipal health indicators related to the quality of water fluoridation. An ecological study was carried out in Espirito Santo state (ES), based on data from the Drinking Water Quality Surveillance Information, from 2014 to 2017. The non-parametric Mann-Whitney and Spearman tests were applied to compare municipal indicators with the availability of information and the quality of fluoridation, respectively. Fluoridation quality was calculated to define the percentage of fluoride concentration values in each municipality within the range of the optimal level corresponding to the maximum benefit for preventing dental caries and minimum risk for the occurrence of dental fluorosis. The proportion of 80% or more samples were defined as a compliance criterion. In 2014, 62.8% of the municipalities had information available, and 16.7% performed analyses of fluoride concentration. The percentage of available data increased about 30%, in 2017, with 3.8% referring to fluoride. The quality of fluoridation remained high (> 80%) in ES in almost every year, except in 2014. The municipalities with the largest population, the highest GDP per capita, and the lowest coverage of the oral health team exhibited a greater availability of information about fluoride (p <0.05). The child mortality rate showed a strong negative correlation with the quality of fluoridation. The findings reinforce the importance of directing public policies that ensure the correct practices for monitoring and maintaining the quality of fluoridation.

Quality of drained waters of the irrigated rice frames during the establishment of pre-germinated cultivation system

Abstract: Irrigated rice ( Oriza sativa L .) pre-germinated production systems occupy approximately 100 thousand ha, annually cultivated in Rio Grande do Sul State, mainly in poorly drained areas, and with infestation of competing plants, especially red rice ( Oriza sativa L.). This system constitutes the main technologic resource for rice crops produced on an ecological basis, by means of soil tillage and water management. Despite this, water outlets, specifically after seeding, have outstanding agronomic and environmental implications. Loss of nutrients and the physical and chemical quality of drained water have been questioned by public research and environmental institutions. This work evaluated the effects of different soil tillage systems and retention time of water in irrigated rice frames. The experiment was conducted in Viamao town, Rio Grande do Sul State. Two different soil tillage systems and four different times of frame drainage after seeding were investigated. Results showed that the main limiting attributes of water quality were turbidity, biochemical oxygen demand (BOD) and phosphorus (P) content, reaching 1800 TNU, 115 mg L -1 , and 1.6 mg L -1 , respectively. These attributes showed values higher than established environmental thresholds. Water quality was inappropriate to discharge directly into water courses, regardless of treatments.An alternative is the immediate placement in rice production areas, in more advanced development stages of plants. Pre-germinated rice crops require a system framework to avoid nutrient loss and consequent reduction of soil fertility.

Aquatic entomofauna and biotic index along the Pindo Grande River, Montano Bajo Forest, in Pastaza Province, Ecuador

Abstract: Pindo Grande River water quality was analyzed during rainy seasons of 2014 and 2017 and dry seasons of 2015 and 2016. Specimens were collected using surber net, kick net and manual stone collection, from five different sites along the river. In the laboratory, specimens were identified to the lowest possible taxonomic level. Taxon richness, abundance, diversity, trophic niches, and Biological Monitoring Working Party for Colombia (BMWP/Col) index were assessed. A total of 1,695 specimens belonging to 95 taxa were collected, including 57 taxa in rainy seasons and 38 taxa in dry seasons. Class Insecta was the most abundant (98.6%). Richness was highest (3,427) at M1000 collection sites in rainy and dry seasons and varied from moderate to high (13–35) at other sites. All sampling sites had medium diversity, and organisms belonged to three trophic categories: herbivores, detritivores, and predators. Environmental water quality was medium at most sites (BMWP/Col = 102–150). All sites exhibited good conservation status (BMWP/Col = 192–152) in the rainy season; only two sites presented medium conservation status (BMWP/col = 93–67) in the dry season. Principal component analysis indicated that main variables associated with sites were NO 3 and COD in upstream areas in the rainy season and O 2 in the dry season. Downstream areas were grouped based on depth and width of the river in the rainy season and on pH, PO 4 , and conductivity in the dry season. According to analysis, the Pindo Grande River has preserved epibenthic communities; it is an oxygenated stream, but its habitats have been gradually affected by anthropogenic activities.

Quality of raw water in the Guandu Basin of Rio de Janeiro state during water crisis of 2020

Abstract: At the beginning of 2020, about 9 million inhabitants of the Metropolitan Region of Rio de Janeiro, dependent on the Guandu Basin, experienced a water-supply crisis when their water tasted badly and gave off an odor. This work presents the results of analyses of the sanitary quality of raw water in this system at two different times during the water crisis, with respect to the presence of cyanobacteria found using metagenomic studies, and cyanotoxins, microcystin (MC) and saxitoxin (SXT) quantified by ELISA. Analyses of raw water quality parameters were carried out through the determination of total coliforms and Escherichia coli levels and some physical-chemical parameters. The raw water collected in both periods presented levels of Escherichia coli levels above the maximum allowed values (MAV) described in Resolution 357/2000 of the National Environmental Agency, as well as the levels of MC in a filter sample. The physical-chemical parameters analyzed and the SXT levels were in accordance with this resolution. The most abundant cyanobacterial genus in the critical period was Planktothricoides sp. Therefore, it is necessary to implement basic sanitation in cities upstream from the point of capture of raw water from this source, so that events similar to those that occurred in the 2020 water crisis do not recur.

Simulation of nitrate and potassium concentrations in soil solution using parametric models and Hydrus-2D

Abstract: This study estimated the nitrate and potassium concentration in the soil solution of drainage lysimeter using the mathematical models developed by Vogeler et al. (1996) and Munoz-Carpena et al. (2005) and the computational model Hydrus-2D, while comparing the simulated and observed data using statistical parameters. The cultivar used for the study was ‘Prata Gorutuba’. The experimental plots were six lysimeters of drainage. Fertigation was performed weekly. The mathematical models developed by Vogeler et al. (1996) and Munoz-Carpena et al. (2005) were used to determine the specific concentration of a given ion (Ci). The Hydrus software was used to simulate the dynamics of nutrients. The concentrations of nitrate and potassium in the soil solution were estimated by the model of Vogeler et al. (1996), adapted to the linear type CEw-Ci ratio and simulated by the Hydrus model, resulting in an acceptable characterization of the distribution of these nutrients.