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Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The knowledge of factors that influence the waters present in the hydrographic basins is extremely important for efficient management, considering its multiple uses. In this regard, the present work aims to apply mathematical modeling tools, expressed by the HRI-Hydro Tools, the hydrological model of large basins and WARM-GIS Tools, to carry out the physical characterization, hydrological modeling, and the quantitative water balance, for the Jaguarão River hydrographic basin (JRhb). In two scenarios, monthly-based, the reference flow adopted was Q90. Further the water stress index (WSI) was applied for each section of the JRhb drainage network, with emphasis on the analysis of the influence of multiple uses of water in the basin, especially for irrigation. The water withdrawal index (WWI) was used to develop a diagnosis of the watershed level of scarcity, taking into account the annual water commitment, to improve the quantitative representation of water for the JRhb. The results of the hydrological modeling performed showed that, in general, the model presented a good performance both in the calibration and in the validation of the studied periods. The WSI representation showed that in the current scenario (realistic scenario) the basin has been suffering great water stress in the months that comprise the summer season (December, January, February, and March). In addition, the application of the WSI exposed the great influence of water use in the production of irrigated rice in this territory. This result was supported by WWI, which revealed sub-basins that were in a vulnerable state, requiring intensive management and major mitigation efforts. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We aimed to understand how the environmental variability produced by water parameters, land use, and land cover in small streams affects aquatic hyphomycete and invertebrate assemblages associated with leaf litter. Land use and land cover were quantified in the drainage area of streams located in the subtropical portion of the Atlantic Forest. We incubated Nectandra megapotamica leaves in streams and, after 30 days, collected decomposing litter to analyze associated aquatic hyphomycetes and invertebrates. Dissolved oxygen was associated with the distribution of aquatic hyphomycetes. On the other hand, 4,068 aquatic invertebrates were found, assigned into five functional feeding groups (FFG). Native vegetation and water temperature were the variables responsible for structuring the invertebrate assemblages associated with detritus. Native vegetation, dissolved oxygen, and total dissolved nitrogen were responsible for the structuring of FFGs. Streams that showed high rates of agriculture and urbanization in the drainage area showed low leaf mass loss. Our study demonstrated that the presence of anthropic uses and reduced native vegetation in the drainage area affected the assemblages of aquatic hyphomycetes and shredders, which are key players in the process of leaf decomposition in streams. [ABSTRACT FROM AUTHOR]

Temporal variation in limnological characteristics favors an increase in aquatic macrophyte diversity in Neotropical riverine environments. We assessed temporal and environmental variability in the aquatic macrophyte community in riverine environments of the Tapajós river basin, southern Amazonia, Brazil. Hydroperiod, type of riverine environment, limnological variables, and surrounding woody vegetation were found to influence aquatic macrophyte richness, cover, and dry and fresh biomass. A total of 98 species from 68 genera and 40 families were recorded. The greatest observed richness in streams was during the dry period. Richness, cover, and biomass were greater in lagoons and rivers during rising water and flood hydroperiods. Amphibious and emergent species had higher biomass in flood and receding water hydroperiods. Higher richness, cover, and fresh biomass were mostly related to electrical conductivity. Suspended and dissolved solids reduced species richness in all environments. Greater tree abundance in the surrounding vegetation was associated with higher macrophyte richness in streams and with macrophyte cover and biomass in rivers. The aquatic macrophyte community in southern Amazonia is subject to variation in riverine ecosystem type, tree composition and structure in surrounding vegetation, hydroperiod (temporal variation), and limnological parameters (environmental/temporal variation). [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Eucalyptus afforestation may affect stream ecosystems, but the magnitude of these effects on water quality and biota in subtropical lowland streams is little understood. We evaluated the potential effects of Eucalyptus afforestation on water quality and macroinvertebrate assemblage. Water quality parameters and macroinvertebrate assemblages were sampled in summer and winter in 30 streams covering an afforestation gradient (from 0.05 to 96% of the catchment area) and tested their relationship. We analyzed the taxa density distribution in afforestation and water parameters using the Thresholds Indicator Taxa Analyses (TITAN). Nutrient concentrations, conductivity, and total dissolved solids showed positive responses to the increase of afforestation, but the responses varied among seasons. Macroinvertebrate metrics showed negative (Ephemeroptera-Trichoptera-Plecoptera (EPT), sensitive families, scrapers), and positive (Chironominae, Oligochaeta) responses to the afforestation. Densities of sensitive taxa (mostly EPT) decrease with an increase in Eucalyptus afforestation, which is also related to water quality and possibly to habitat changes attributed to afforestation management. The use of water quality parameters in combination with macroinvertebrates assemblage contributes to managing these streams under catchment afforestation. [ABSTRACT FROM AUTHOR]

The way water resources behave in the face of changes in land use are essential for managing a watershed. The Ibicuí river basin, located in the center of the state of Rio Grande do Sul, Brazil, has great agricultural potential and peculiar characteristics regarding its hydrological regime. Changes in land use and land cover with the purpose of expanding economic activities in this area can generate major impacts on the flow regimes of this watershed. This study shows an analysis of the influence of land use and land cover changes on the flow regime in the Ibicuí river basin from the large-basin hydrological model (MGB-IPH), considering maps of land use history and vegetation cover in the study area. The results were used to analyze the changes in the maximum and minimum annual and monthly average flows. The efficiency of the model was evaluated by the Nash-Sutcliffe coefficient (between 0.636 and 0.801) for peak flows and by the Nash-Sutcliffe log (between 0.682 and 0.863) for recession flows, indicating high correlation and low volume error (- 0.45 to - 8.20%). The greatest change in land use was the forest coverage reduction associated with agriculture land use. As a result, an increase in the average monthly flows and in the reference flow Q90 was verified. In some sub-basins, a significant modification in the reference Q90 flow and maximum flow was verified. The Mann-Whitney test showed that the results were accurate. The results indicated that changes in forest coverage and land use have an impact in the flow regime in the Ibicuí Watershed. [ABSTRACT FROM AUTHOR]

Tropical rivers are the main destinations for tailings from urban, industrial and agricultural activities in the region studied. The present study aimed to investigate if early stages of zebrafish (Danio rerio) development is a viable biological model to assess the toxicity of surface waters of tropical rivers, and whether that toxicity could be correlated to standard water quality indexes. Embryos were exposed to samples from 55 sites from 10 hydrographic basins of rivers in Pernambuco State, northeastern Brazil. Lethality rates, sublethal toxicity based on the general morphology score (GMS) and frequencies of abnormalities were analyzed. Significant mortality was observed in samples of 7 basins. The GMS indicated significant delay in embryo-larval development in 50% of the samples. The highest toxicity was detected in basins within Recife metropolitan area, where 61% of the samples caused sublethal toxicity. Most frequent developmental abnormalities included non-inflation of the swim bladder, delayed hatching and blood stasis. The highest frequencies of blood stasis were detected in samples with highest NH3 concentrations, corroborated by a positive correlation suggesting the existence of a causal relationship. A significant correlation was detected between water quality indexes and GMS with a greater toxic effect being observed in samples collected in areas of greater urban density and greater contamination by domestic sewage. This study demonstrates that the early stages of the zebrafish is a viable ecotoxicological model to assess the toxicity of surface waters and can contribute to a better understanding between the chemical composition and the adverse effects suffered by fish early life stage fish in tropical rivers. [ABSTRACT FROM AUTHOR]

Environmental vulnerability is an important tool to understand the natural and anthropogenic impacts associated with the susceptibility to environmental damage. This study aims to assess the environmental vulnerability of the Doce River basin in Brazil through Multicriteria Decision Analysis based on Geographic Information Systems (GIS-MCDA). Natural factors (slope, elevation, relief dissection, rainfall, pedology, and geology) and anthropogenic factors (distance from urban centers, roads, mining dams, and land use) were used to determine the environmental vulnerability index (EVI). The EVI was classified into five classes, identifying associated land uses. Vulnerability was verified in water resource management units (UGRHs) and municipalities using hot spot analysis. The study employed the water quality index (WQI) to assess the EVI and global sensitivity analysis (GSA) to evaluate the model input parameters that most influence the basin's environmental vulnerability. The results showed that the regions near the middle Doce River were considered environmentally more vulnerable, especially the UGRHs Guandu, Manhuaçu, and Caratinga; and 35.9% of the basin has high and very high vulnerabilities. Hot spot analysis identified regions with low EVI values (cold spot) in the north and northwest, while areas with high values (hot spot) were concentrated mainly in the middle Doce region. Water monitoring stations with the worst WQI values were found in the most environmentally vulnerable areas. The GSA determined that land use and slope were the primary factors influencing the model's response. The results of this study provide valuable information for supporting environmental planning in the Doce River basin. [ABSTRACT FROM AUTHOR]

The increase in the number of environmental disasters in recent years has prompted a reorientation of research and programs. While significant studies have primarily focused on the physical aspects of these disasters, it is important to recognize that the vulnerability of populations is not solely dependent on the proximity of the threat source or the physical nature of the disaster. Social factors also play a crucial role in determining vulnerability. To enhance natural disaster management, it is vital to understand how social disparities influence the vulnerability of populations and develop strategies tailored to specific characteristics. This study proposes a set of 16 theoretically significant variables to measure and map vulnerability in Brazil. They were grouped into three indicators, social, economic, and infrastructure aspects of the population, obtained from the Brazilian census database. The Córrego do Feijão tailings dam, in Brumadinho, and the Casa de Pedra tailings dam, in Congonhas, were taken as case studies. The vulnerability of 48 municipalities and 3732 census sectors from the Paraopeba River Basin was explored from two different perspectives: Where the disaster has already happened, and where it could happen. The index and indicators used were developed in an open-source software and the maps in a geographic information system. The results show considerable variability. The most vulnerable municipalities are in the lower part of the basin while the high part of the basin vulnerable. This paper presents methodological and empirical contributions to understanding the social dimensions of vulnerability and their implications for the preparation, response, and recovery of affected communities in the face of environmental disasters. [ABSTRACT FROM AUTHOR]

Changes in land use have been occurring in a continuous and disorderly way in recent decades due to rapid population growth and the growing demand for food. These constant changes result in a series of harmful effects to the environment, especially to water resources, significantly changing their availability and quality. This study aims to evaluate the degradation potential of watersheds through an evaluation of some environmental indicators using arithmetic means to construct an index called in this research "index of potential environmental degradation" (IPED). To form the IPED, the hydrographic sub-basins of the Sorocabuçu River, located in the central west of the State of São Paulo, Brazil, comprised the study area. The results showed that most hydrographic sub-basins, that is, eight units, present degradation values ranging from moderate to very high, resulting mainly from low conservation values of forests plus a use destined to the planting of temporary cultures depending on good physical conditions. On the other hand, only one sub-basin showed a low degradation value. The methodology used for the development of the IPED is easy to apply and an effective tool for environmental analyses. It may contribute to studies and forms of planning and land use management aiming the conservation of water resources and protected areas and reduction of degradation. [ABSTRACT FROM AUTHOR]

Land use and land cover (LULC) planning stands out for listing potentials and limitations to land use aiming to reduce erosion to tolerable limits based on soil characteristics, relief, and socioeconomic aspects of landowners. To demonstrate the possibilities and limitations of agroecosystems diagnosis in large basins through the concept of land use capability, this work proposed a methodology for agro-environmental diagnosis applied to the Doce river basin (DRB) that was validated based on google earth images samples and suspend soil concentration in rivers. The methodology consisted of comparing the land use capability with the intensity of use caused by the LULC. The results showed that DRB is suited for intensive conservationist agricultural uses. However, some regions, are suitable for more intense agricultural activities. The factors regarding relief (slope and recharge) are the most restrictive ones to more intensive use in the basin. Pasture is the main use in the Doce river basin and had the highest percentage of areas used above the land use capability, followed by perennial agriculture and eucalyptus. The methodology of agro-environmental diagnosis based on the concept of land use capability was considered adequate for the diagnosis of agroecosystems at DRB since at a local scale, it was estimated accuracy of 95.5% of the number of exceeding classes in 45 sampled polygons and, at a regional scale, the linear regression between soil use and management index (Ium) and suspended soil concentration in rivers at Hydrographic Regions obtained an R2, RMSEN, and NSE of 0.79, 0.12, and 0.74. [ABSTRACT FROM AUTHOR]

Erosion-soil loss is responsible for long-term environmental impacts due to water resource silting process and biodiversity loss. Studies focusing in erosion-soil loss are important for understanding phenomena affecting the environment. Therefore, this study aimed to analyze and characterize the susceptibility to soil erosion in drainage basins in the municipality of Jataí, located in the southwest of the state of Goiás/Brazil (used as case study model). The places most susceptible to soil losses in the studied context are located in the northwest, southwest and southeast regions of Jataí. The rainfall erosivity (R) indices in the period from 2000 to 2020 were classified as medium (500–750 tn mm ha−1 year−1), high (750–1000 tn mm ha−1 year−1) and very high (> 1000 tn mm ha−1 year−1). With regard to soil erodibility (K), the most prone to erosion are the entisol with a K value of around 0.029 t/ha MJ−1 mm−1 and the entisol with 0.041 t/ha MJ−1 mm−1. As for the topographic factor (LS), values between 3.3 and 5.5, considered moderate, occupy 317.88 km2; the ranges between 5.5 and 7.5, representing 57.69 km2, are considered to have moderately strong susceptibility. Although 46.14% of the analyzed basins have mild-to-moderate susceptibility (FAO), in an area of just over 1316.46 km2 (18.35%), there are susceptibilities of severe to very severe, formed by the soils entisol, ultisol and oxisols, with slopes between 45 and 75%. This study demonstrated to be useful for proposing environmental monitoring policies of drainage basin areas affected by erosion. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Freshwater ecosystems are among the most threatened habitats on Earth, due mainly to anthropogenic pollutants made up of complex mixtures. The Iguaçu River is world famous for the Iguaçu Falls and highlighted by its endemism. Unfortunately, it is considered the second most polluted urban river in Brazil. We aimed to perform an environmental evaluation of Neotropical streams in the Iguaçu River basin, using a multibiomarker approach from a land use and landscape perspective. A set of biomarkers in the fish Psalidodonbifasciatus was analyzed using an Integrated Biomarker Response (IBR) index and correlated with surrounding land uses. Agricultural and urban sites presented more alterations compared to references sites, with elevated protein carbonyls at agricultural sites, increased DNA damage and depletion of glutathione S-transferase at urban sites and decreased glutathione associated with higher histopathological indices at urban and agricultural sites. The IBR shows a consistent increase in negative effects in anthropized areas, with similar values at agricultural and urban sites. The multibiomarker approach, associated with a well-elaborated sample design and a statistical analysis, is an ideal method to obtain more conclusive results about the effects of human activities, revealing the effective result of exposure in the real world. [ABSTRACT FROM AUTHOR]

Forest fires negatively impact ecosystem services, affecting human welfare. The present study proposes a Forest Fire Risk Indicator (FFRI) based on the Fire and Burn Risk Indicator (FBRI). The instrument was applied to the Sorocabuçu River Basin in São Paulo State, Brazil. The FBRI was initially obtained by using the factors that most contribute to the start or spread of fires according to the literature. These factors were later grouped into anthropogenic, topographic, land cover/land use, and climatic variables. The factors of each variable were classified into intervals to which a fire risk value was assigned ranging from 0 (null risk) to 1 (very high risk). By applying the Analytical Hierarchy Process, we obtained the final FBRI, after which the FFRI was created. The final FBRI showed predominantly high risks (64.78%) throughout the basin, as well as the FFRI (82.56%). The present study evidences that most forest fragments need measures for ecosystem protection. This can be done in different ways such as monitoring through fire towers and conduction of environmental education activities. [ABSTRACT FROM AUTHOR]

The application of environmental fragility in studies evaluating watersheds can guide policy decisions on monitoring and land use management, improving water quality for public supply. The aim of this study is to characterize the environmental fragility of public water supply watersheds and relate it to water quality factors. Physical, chemical, and microbiological data associated with water quality were measured in nine rivers. Landscape features were used to calculate fragility, such as slope, soil type, and land use and land cover were assessed with the help of geoprocessing tools, in addition to Köppen-Geiger-based climate characterization. The municipalities with the largest areas classified with high fragility are: Guaraniaçu, Catanduvas and Cascavel, requiring greater attention. The variation in fragility responded mainly to the values of temperature, pH, E. coli and COD, which may be strongly associated with the difference in land use and slope of the evaluated areas. [ABSTRACT FROM AUTHOR]

In recent years, the demand for clean water has been growing all over the world despite the different threats posed, including increasing pollution, increasing deforestation and climate change. Industrial activity is the second largest consumer of water, so highly industrialized regions are more susceptible to water stress. In this sense, reuse strategies have been progressively discussed and used around the world; however, in Brazil there is still place for many advances, whether due to lack of incentives, cultural issues in society, or poor regulation of the subject. The objective of this work was to carry out a diagnosis of raw water uptake by industries in one Hydrographic Region of the state of Rio de Janeiro and to propose a discussion on the adoption of water reuse practices for non-potable purposes from the use of treated effluents. A survey of the theoretical framework on the subject was carried out, as well as an analysis of sustainability indicators and reports of the companies, including the current licensing processes of large undertakings consuming water resources. With this study, it was possible to obtain the average cost of implementing a water reuse unit for an industry in the state of Rio de Janeiro-Brazil, which, despite still being expensive, has a strong tendency to use due to world water shortages. Finally, it was concluded that the state of Rio de Janeiro has a threat of water scarcity that could be aggravated in the coming years, if measures and investments in supply alternatives are not adopted (water reuse), and improvement in all stages of water management water resources. [ABSTRACT FROM AUTHOR]

This study provides the sedimentation rates (SR) of three drainage basins at Itaipu Reservoir (Paraná State, Brazil) by applying 210Pb and 137Cs geochronological methods (CFCS and CRS models). The results based on the CRS model showed SR increasing in São Francisco Verdadeiro (SFV) and Ocoí (OCO) over the last decades (0.61 and 0.43 g cm2 yr−1, respectively). Arroio Fundo (ARF) showed the opposite trend with decreasing accumulation (0.19 g cm2 yr−1). The SR results indicate that precipitation changes in a period of rapid agricultural development influence each sub-basin differently depending on its drainage size area and watershed conditions. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The landscape geoecology aims at a systemic and integrated comprehension of physical–natural and anthropic components. It cooperates to identify and map landscape units, as well as to define indicators that establish their geoecological diagnosis mitigating measurements for preservation and use. The objective is to determine the state and geoecological diagnosis of landscapes of the Formoso River Watershed, located in the municipality of Bonito/MS, Brazil. The methodology consists of four stages: (i) the organization to define the study area and worked themes; (ii) the inventory and analysis characterizing the rocks, soils, relief, and anthropic use to define the landscape units; (iii) the diagnosis to establish the condition and geoecological diagnosis of landscapes; and (iv) the prognosis and proposals to define recommendations, envisioning trend, and desired scenarios for the watershed. The delimitation, classification, and mapping of landscape units, on a scale of 1:100,000, allow to identify the existing landscape heterogeneity. Thus, the condition and geoecological diagnosis are determined highlighting that extensive areas of "Altered Landscapes" potentialize the current watershed environmental problems: a fact that contributes to define future development scenarios, as well as recommendations to ensure a harmonious use to preserve the landscapes. The present work aims to contribute to the advancement of landscape geoecology and the study of tropical karst landscapes in a theoretical– methodological and practical way. Moreover, it is essential to support public power decision making, and assist researchers, institutions in charge of conservation and tourism to search solutions to watershed current and future environmental problems. [ABSTRACT FROM AUTHOR]

The dynamics of total phosphorus (TP) in 18 strategic reservoirs of the high-density reservoir network of the Brazilian semiarid was evaluated during the wet and dry periods for the past 12 years. Seasonal overlying concentrations presented no significant differences for about 90% of the reservoirs (p>0.05). This was attributed to a trade-off between the hydrological/limnological processes occurring in the two seasons. Then, a transient complete-mix mass balance model was applied with particular adaptations for the tropical semiarid reservoirs to estimate the TP load for each season. Because of the relatively well-mixed conditions and high hypolimnetic dissolved oxygen concentrations during the wet season, the wet load was assumed to represent the external TP load. On the other hand, because of the absence of reservoir inflow during the dry season, phosphorus release under anoxic sediment conditions and wind-induced resuspension under shallow water depths, the dry load was assumed to reflect the internal TP load. The maximum external loads were related to peak inflows, notably after drought periods. Consistently, the largest internal loads were obtained during the drought periods, when the reservoirs were shallower and more prone to phosphorus release and resuspension. By comparing the impact of the two input load types, the wet period load was predominant in 72% of the reservoirs. The areal phosphorus loads ranged from 0.66 to 7.29 gP m2 year−1, which were consistent with the literature, despite the very high density of reservoirs. Finally, power-law curves including data for all studied reservoirs were adjusted between the dry period load and volume, dry and wet period loads, wet period load and inflow, and total load and catchment area, resulting in satisfactory R2 (0.84–0.98). [ABSTRACT FROM AUTHOR]

Fipronil (FIP) is a broad-spectrum insecticide used in the industrial, residential and agricultural sectors, which presents environmental and human health risks. Studies report its presence in aquatic environments in several countries, but in Brazil reports are scarce. The aim of this work was to evaluate the presence of fipronil and fipronil sulfone in surface waters through a validated analytical method by LC–MS according to INMETRO and USEPA in eight sampling sites in two seasons (summer and autumn, 2020) in Guandu River basin, in the state of Rio de Janeiro. FIP was quantified in the concentration range of 0.132–2.44 μg/L, while FIP-S was detected in most samples. This is the first study on the occurrence of FIP and FIP-S in the Guandu River basin, presenting values high enough to justify the need for monitoring studies in a region of great importance for the city of Rio de Janeiro. [ABSTRACT FROM AUTHOR]

During the water crisis of 2015–2016, the construction of small earth-filled dams grew to supply irrigated crops of the north of Espírito Santo-ES, Brazil. This paper reports the hydrogeochemical study of eight reservoirs conducted between 10/2016 to 11/2017 to assess the water suitability for agricultural purposes and its risk to irrigation systems. The reservoirs of São Mateus (SM) are located in large drainage basins with many impoundments upstream. Nova Venecia's reservoirs (NV) have small and circular drainage areas with few, or any, upstream dams. The results are consistent with freshwater classification and Na-Cl composition to all reservoirs. Nevertheless, canonical discriminant analysis and Spearman's coefficients revealed distinct composition and patterns of correlations between municipalities. The mean permeability index of 53 and the low risk of sodicity and salinization (C1S1) demonstrate that these waters' use is harmless to the soil and crops. However, the phosphate contents make the new reservoirs susceptible to algae blooms. The same reservoirs also presented total solids and Fe levels above the tolerable limit for safety irrigation use, imposing a severe risk of clogging. The low replenishment of SM's reservoirs reflects the dispute over water resulting from the high number of impoundments in these drainage areas. The drought that preceded the study diminished the drainage basins' vegetation cover, favoring soil particles' runoff, elevating the TS and Fe levels, especially in the recently built reservoirs. Farmers must control soil erosion to avoid water quality compromise, to reduce the risk of failure and the irrigation system's maintenance cost. [ABSTRACT FROM AUTHOR]

This paper aims at quantifying natural and artificial radionuclides, trace and major elements in sediments collected along the Tietê River basin. The results obtained for Cd, Cr, Cu, Ni and Zn, indicated that the region of "High Tietê" is highly polluted, followed by the region of "Middle Tietê" and the region of "Low Tietê" does not present evidence of contamination. The natural radionuclide concentrations were of the same order of magnitude of world average values and can be defined as basal levels of the region. Cesium-137 activity concentration ranged from 0.22 ± 0.08 Bq kg−1 to 0.96 ± 0.12 Bq kg−1. [ABSTRACT FROM AUTHOR]

Several recent studies were conducted concerning species richness and spatial-temporal distribution of Simuliidae (Diptera: Culicomorpha), but there are still gaps in knowledge regarding these species, mainly when it comes to their local abundance and regional distribution patterns. The aim of this study was to investigate the distribution and diversity of Simuliidae in a watershed located in the Pampa biome of southern Brazil. Abiotic factors were evaluated during two seasons, spring and autumn, and at two spatial scales. These spatial scales consisted of three regions of the Piratinim river drainage basin (upper basin, middle, and lower courses) and three stretches of tributary streams (upstream, intermediate, and downstream). Immature stages, consisting of larvae and pupae, were sampled in six streams encompassing a total of 18 sampling points. The results indicated the occurrence of nine simuliid species along the studied area, with the three most abundant being Simulium pertinax, Simulium orbitale, and Simulium incrustatum. It was verified that the structure of the assemblage was mostly influenced by local factors, i.e., stream stretches, but also by those of a wider scale, i.e., watershed regions. Some species showed spatial distribution patterns; Simulium orbitale and S. jujuyense were associated with downstream areas, while S. pertinax was associated with upstream areas. Concerning regions, S. pertinax was less frequent in the lower region of the basin. Environmental variables such as temperature and stream width were also important. Our results show new and relevant information regarding the structure of simuliid assemblages in the Pampa biome. [ABSTRACT FROM AUTHOR]

Organophosphate esters (OPEs) are substances globally used as flame retardants and plasticizers that have been detected in all environmental compartments. This study aimed to evaluate the occurrence and sources of ten OPEs in the Piracicaba River Basin (Brazil). Twelve sampling sites were selected in five rivers with different pollution sources; six sampling campaigns were performed encompassing dry and wet seasons. ΣOPEs ranged from 0.12 to 6.2 μg L−1; the levels in urban areas were higher than in rural and non-urban areas, but no overall tendency concerning the seasonal effect on OPEs concentrations was observed. Tris(2-butoxyethyl) phosphate (TBOEP), tris(2-chloroisopropyl) phosphate (TCIPP), and tris(1,3-dichloroisopropyl) phosphate (TDCIPP) were the most abundant and frequently detected compounds. Nine OPEs were detected at higher concentrations in a site affected by effluents from textile industries. An acute toxicity test using Daphnia similis was performed for tris(2-ethylhexyl) phosphate (TEHP) for the calculation of a preliminary predicted no effect concentration (PNEC). The risk quotient (RQ) approach was applied and risk to aquatic environment related to TEHP levels was observed in areas adjacent to textile industries, but more toxicity studies are required for the determination of a more reliable PNEC. [ABSTRACT FROM AUTHOR]

In Brazil, specifically in the Doce River basin, there is still a great lack of studies on temporal and spatial trends in water quality, since the water quality in the monitoring campaigns is basically evaluated when it comes down to the concentrations of monitored variables. In this sense, the objective of this work was to perform a temporal and spatial trend analysis of water quality data in the Minas Gerais portion of the Doce River basin, Brazil. For this, the Mann–Kendall, seasonal Mann–Kendall and Spearman correlation tests were used in the temporal analysis and the cluster analysis in the spatial analysis. In the analysis of temporal trends, the analyses were performed using the values of the National Sanitation Foundation Water Quality Index (NSFWQI) and the variables that compose it. In the analysis of spatial trends, the stations were evaluated only based on the WQI. With the results of the analysis of temporal trend, it was identified that most stations did not present a statistically significant trend for the WQI. In the stations that presented trends of quality reduction, most of them are in densely populated areas, demonstrating the strong influence of the poor sanitary conditions of the municipalities to the water quality of the basin. When analyzing the variables that compose the WQI, the results found for nitrate demonstrated that water quality deterioration is also affected by the diffuse pollution originating from farming areas. The results for Escherichia coli reinforced the impact of the discharge of domestic effluents and demonstrated the absence of a significative trend is still of concern because it can represent the maintenance of a degradation state in the water bodies. In the spatial trend analysis, the CA grouped the monitoring stations into six clusters based on their similarity among the WQI values, and, together with the results of the other analyses, it was verified that the Caratinga River basin (UGRH5 Caratinga) presented the highest degree of pollution. It was also possible to identify five stations that can be reallocated or deactivated since they have similarities with other stations located in the same watercourse. [ABSTRACT FROM AUTHOR]

This study describes the application of gas chromatography coupled to mass spectrometry (GC-MS) to evaluate the occurrence of 12 CECs—contaminants of emerging concern (bisphenol A, diclofenac, 17β-estradiol, estriol, estrone, 17α-ethinylestradiol, gemfibrozil, ibuprofen, naproxen, 4-nonylphenol, 4-octylphenol, and acetaminophen) in surface waters from Paraopeba River Basin, Minas Gerais State, Brazil. The analytical procedure was validated and applied to 60 surface water samples collected across four sampling campaigns along the upper and middle watershed. Methods for CECs determination involved sample filtration, and solid-phase extraction (SPE) with subsequent derivatization of the target compounds prior to their analysis by GC-MS. The LOQ varied from 3.6 to 14.4 ng/L and extraction recoveries ranged from 46.1 to 107.1% for the lowest spiked concentration level (10 ng/L). The results showed a profile of spatial distribution of compounds, as well as the influence of rainfall. Ibuprofen (1683.9 ng/L), bisphenol (1587.7 ng/L), and naproxen (938.4 ng/L) occurred in higher concentrations during the rainy season, whereas during the dry season, the concentrations of bisphenol (1057.7 ng/L), estriol (991.0 ng/L), and estrone (978.4 ng/L) were highlighted. The risk assessment of human exposure shows that for most contaminants, the concentration is well below the estimated thresholds for chronic toxicity from water intake. However, estradiol and 17α-ethinylestradiol showed concentrations in the same order of magnitude as the guide values estimated for babies. [ABSTRACT FROM AUTHOR]

The present study evaluated the influence of land use and occupation on water quality indices (WQI); the WQI developed by the National Sanitation Foundation (NSF), the WQI adapted by the Environmental Company of the São Paulo State (CETESB), WQI proposed by Bascarón and the Canadian Council of Ministers of the Environment (CCME) WQI, obtained for watersheds located in the Eastern Water Planning and Management Region (BA). The study also analyzed the divergences and similarities of these WQI methods. Water quality data were obtained from the Monitoring Program (Monitora) of Environment and Water Resources Institute of Bahia (INEMA), covering the period from 2008 to 2015, at thirteen (13) sampling sites, with quarterly collections, as well as land use and occupation data. The influence of land use and occupation on water quality indices was assessed by principal component analysis (PCA). The PCA showed that urban and agricultural/pasture areas were influencing factors on water quality variables, such as total phosphorus, biochemical oxygen demand, total nitrogen, turbidity total residues and consequently lower WQI values in the Cachoeira watershed. Among the tested methods to evaluate the water quality of watersheds in the study area, the most similar were the NSF WQI, CETESB WQI, and Objective Bascarón WQI. [ABSTRACT FROM AUTHOR]

Agribusiness is one of the main economic activities in Brazil, which caused the removal of much of its natural vegetation for the expansion of monoculture areas. Once aquatic environments have a direct relationship with the surrounding terrestrial environment, it is essential to understand the monocultures' impact on adjacent streams and, especially, how aquatic communities react to these impacts. Our aim was to verify the effects of different monoculture types on stream benthic macroinvertebrate and fish communities' structure. We compared the environmental characteristics and these communities' structure in four streams located in native vegetation areas and four in each of three monoculture types (sugarcane, citrus, and eucalyptus), all belonging to the Paranapanema River basin, Southeastern Brazil. We found lower pH and dissolved oxygen and higher total phosphorus and fine substrate values in monoculture streams and these variables were also related to the lower abundance of macroinvertebrate groups more sensitive to environmental impacts. However, we did not find differences in fish communities or in their relationship with the different environmental characteristics observed. We also did not observe differences between the monoculture types in all comparisons made, which demonstrate that these plantations, although have different cultivation characteristics, cause similar negative impacts in the streams. Our study demonstrates the physical and chemical impacts of monoculture development on stream headwater communities. Regulatory measures such as increased riparian vegetation and contour farming and terracing may be critical to protect and restore headwater streams from monoculture impacts. [ABSTRACT FROM AUTHOR]

A deep investigation on the trophic structure of a fish assemblage in a reference condition river is important since allow the comparison and determination of the extent in which other sites are degraded. It is especially relevant when we consider a reference condition river located in a basin under influence of several anthropogenic activities, as is the case of the Rio Cipó, an important tributary of the polluted Rio das Velhas Basin, Brazil. We aimed to characterize the trophic structure of the fish assemblage of the Rio Cipó using the carbon (δ13C) and nitrogen (δ15N) stable isotopes of fish and several available food resources sampled at two sites along the Rio Cipó in the dry and wet seasons. We found that the δ15N of fishes change among trophic guilds, but not change between sites and seasons. The δ13C values in turn, varies among trophic guilds and between seasons, and the changes between sites are not very expressive. Detritivorous fish presented the greatest variation in δ13C values. Although all detritivorous species appeared to consume the same basal resources (algae, periphyton, POM and CPOM), the proportion of assimilation of each resource varied among them. Two individuals of Myleus micans (herbivorous) and two of Piabarchus stramineus (omnivorous), were found to differ substantially within the food web by presenting the most enriched values of δ15N and δ13C in the wet season at the site close to the confluence with other rivers. These outliers had influence in the broad isotopic niches of herbivorous and omnivorous fish. This result suggest that these species have a large spatial range and may be feeding in places with resources enriched in δ15N and δ13C, outside of the Rio Cipó, as well as highlights the importance of considering the influence of downstream polluted areas on the trophic structure of this reference condition river. [ABSTRACT FROM AUTHOR]

The objective of the present study was to evaluate the water quality data in the Minas Gerais portion of the Doce River basin in order to analyze the current monitoring network by identifying the main variables to be maintained in the network, their possible sources of pollution, and the best sampling frequency. Multivariate statistical techniques (factor analysis/principal components analysis, FA/PCA and cluster analysis, CA) complemented by the analysis of violation of the framing classes were used for this purpose. Water quality variables common to 64 monitoring sites were analyzed for the base period from 2010 to 2017. The water quality variables were analyzed considering the different monitoring campaigns: (a) partial campaigns; (b) total campaigns; and (c) monthly campaigns. It was identified from the FA/PCA results, that, when the partial campaign data were analyzed, the variables selected represent the high susceptibility that the basin presents to erosion and the release of domestic effluents in its water bodies. When the data of total campaigns were evaluated, representative variables of the contamination by heavy metals from industrial and mining activities were included. Therefore, the analysis of violation of the framing classes made possible to identify five critical variables: thermotolerant coliforms, dissolved iron, total phosphorus, and total manganese, which reinforced the results obtained in FA/PCA. Based on the results of the analyses, it was recommended to include variables associated with heavy metal contamination in the partial campaigns, prioritizing the dissolved iron and total manganese, as well as total chloride sampling only for the total campaigns. The evaluated data from the monthly campaigns, the CA showed that although the quarterly monitoring frequency is satisfactory, the monthly monitoring is more appropriate for the monitoring of water quality in the Minas Gerais portion of the Doce River basin. [ABSTRACT FROM AUTHOR]

Impacts on urban water resources are invariably caused by the development of urban centers and the occupation of the watershed. The release of untreated effluents and urban runoff are sources of metals in adjacent water bodies. It is therefore important to conduct studies on the occurrence of these trace elements in the environment and the risks posed to human health. The aim of the present study was to determine Cd, Pb, Cu, and Zn concentrations in water bodies located in the Bacanga and Cachorros watersheds and correlate the occurrence of these elements with physicochemical variables of the water (temperature, pH, dissolved oxygen, and electrical conductivity). The variables were determined at the collection site with the aid of a multiparameter kit. Heavy metal concentrations were determined using anodic stripping voltammetry. The results revealed that the streams were not contaminated with the metals analyzed. The only exception was copper in the Limoeiro and Murtura streams, both of which are located in the industrial complex. [ABSTRACT FROM AUTHOR]

The process of anthropization of the Cerrado has generated diverse environmental liabilities, such as a reduction in biodiversity, degradation of water resources, and alteration of the quality and quantity of water in local water bodies. Thus, the objective of this study was to evaluate the evolution natural regeneration processes of environments under anthropic influences in relation to variations in climatic conditions and the recovery of environmental services in watersheds in the Cerrado. For this purpose, the watershed in the Federal Institute of the Triângulo Mineiro (IFTM) Uberaba-MG Campus was used. The dynamics of natural regeneration were evaluated using the vegetation index (MOD13Q1) and gross primary production (GPP; MOD17A2), which were correlated with the climatic variables and waterflow in the watershed. The characteristics of vegetation dynamics, climatic variables, and flow were determined by descriptive analysis and deviations, and the relationship among variables was determined using multivariate analysis. The process of natural regeneration presented a positive pattern of vegetation expansion in environments under anthropic influence in the Cerrado, which was due to the seasons, time, and climatic elements, and was observed through the temporal dynamics of normalized difference vegetation index NDVI and GPP in the watershed. Natural regeneration is determined by two climatic elements rain and air temperature with rain driving vegetation growth, thereby directly influencing the dynamics of natural regeneration and the recovery of environmental services. [ABSTRACT FROM AUTHOR]

Soil erosion affects agricultural production by reducing the area of rural properties and altering the dynamics of watersheds. Gullies are a complex and irregular type of erosion form that can reach large dimensions, and studying gullies to stabilize erosion processes is a challenge. This study aims to understand their environmental relationships as a basis for future research and to recover land degraded by soil erosion. We combined mapping techniques using geographic information system (GIS) with temporal evolution of land use and fractal dimensions of gullies using FracLac to determine the stability of gullies in a watershed in south Minas Gerais (Brazil). We used R software to apply linear regressions and tested the statistics to verify the compatibility of the model. Environmental characteristics of the watershed contribute to the formation of gullies, but human activities influence the deflagration of these features. The temporal evolution of the land use demonstrated that nearly 50% of the watershed was used as pastures throughout the years, which contributed to soil degradation. The evolution of the fractal dimension showed fluctuations over the years, indicating that the gullies are not stable. The regressions suggest that the vegetation, geology, land use, channel order, and curvature may influence the fractal dimensions of gullies. We concluded that human activity influences the evolution of gullies; the use of techniques such as vegetation measures can contribute to the stabilization of gullies. We also concluded that fractal analysis is an interesting tool for performing environmental evaluations of irregular and complex features, such as gullies. [ABSTRACT FROM AUTHOR]

The mining sector has great importance to the economic activity in Brazil. However, it is also responsible for several environmental impacts such as the rupture of the Fundão dam (Mariana, Brazil) that resulted in the spillage of 50 million m3 of mining tailings in the Doce River Basin. This study evaluated the acute and chronic effects of Fundão tailings on growth, development, respiration rates, swimming performance, and avoidance behavior of Lithobates catesbeianus tadpoles. Results showed that 96-h exposure to different dilutions (10, 25, 50, 75, and 100%) of a stock solution containing mining tailings (50 g/L) caused no mortality of tadpoles; however, the most concentrated solution decreased the swimming speed of the animals. After 16 days, tadpoles exposed to 25, 50, and 100% treatments had both swimming speed and distance traveled reduced. Oxygen consumption was also decreased in tadpoles exposed to the 100% solution after 20 days. Avoidance test indicated that tadpoles avoided lower tailing concentrations, but a reduced avoidance response was attested to the higher concentrations, probably due to the toxic effects of the residues that prevented animals' displacement. Chemical analysis confirmed the occurrence of cadmium (Cd), lead (Pb), iron (Fe), manganese (Mn), zinc (Zn), and aluminum (Al) in Fundão tailings and its presence in the mouth and inside the intestine of treated tadpoles indicated the ingestion of metals by these organisms. This study showed that even presenting low lethal toxicity, long-term exposure to mining tailings from Fundão dam caused morphophysiological and behavioral damage in tadpoles. [ABSTRACT FROM AUTHOR]

The nonparametric test of Kruskal–Wallis and relative risk were used to evaluate surface water quality allowed to an identification of the most degraded water bodies in Piracicaba River and Paraopeba River basins, two important hydrographic basins in Brazil. Total manganese, dissolved iron, and fecal contamination indicator were considered the most relevant parameters for the characterization of water quality in the basins. The Peixe River, in Nova Era, and Pedras Creek, in Betim, were considered the most impacted water bodies in the Piracicaba River and Paraopeba River basins, respectively. The analysis of violations and the relative risk confirmed that both basins are subject to impacts resulting from economic activities. On comparing the relative risks, the Paraopeba River basin showed a higher risk of violation for 5-day biological oxygen demand (BOD5), total manganese, total phosphorus, total suspended solids, and turbidity, while the Piracicaba River basin showed a higher risk of violation for fecal contamination indicator. The release of domestic sewage and industrial effluents, mining activities, and diffuse pollution from agriculture and pasture areas were responsible for the surface water quality deterioration in these basins. The results show the need for investment in basic sanitation, improved treatment efficiency for industrial effluents, adequate soil management, riparian vegetation preservation, and environmental education actions. [ABSTRACT FROM AUTHOR]

The Velhas River sub-basin, which is located in the third-largest river basin in Brazil (São Francisco), is in an advanced state of degradation. In this work, the surface water quality of the Velhas River Basin was studied at 65 monitoring sites; 16 water quality parameters were sampled quarterly for 11 years (2008 to 2013). Cluster analysis (CA) and a nonparametric Kruskal-Wallis test were associated with the analysis of violations to water quality standards to interpret the water quality data set from the Velhas River Basin and assess its spatial variations. The CA grouped the 65 monitoring sites into four groups. The Kruskal-Wallis test identified significant differences (p < 0.05) between the groups formed by CA. The results show that watercourses located in the upper region of the Velhas River Basin are more affected by the release of industrial effluent and domestic sewage, and the lower region is more affected by diffuse pollution and erosion. This association between multivariate statistical techniques and nonparametric tests was effective for the classification and processing of large water quality datasets and the identification of major differences between water pollution sources in the basin. Therefore, these results provide an understanding of the factors affecting water quality in the Velhas River Basin. The results can aid in decision-making by water managers and these methods can be applied to other river basins. [ABSTRACT FROM AUTHOR]

Abstract: Substances derived from anthropogenic activities induce changes in the physical and chemical characteristics of the aquatic environment. Physicochemical and biological studies are necessary to understand how changes in landscape affect the health of the aquatic environment. The main goal of this study was to evaluate how the landscape at different spatial scales affects (1) water quality and (2) the health status of Heptapterus mustelinus, based on several biomarkers. During the dry season, individuals were caught in three sites with different degrees of anthropogenic activity. The quality of the terrestrial environment was assessed using the Riparian Quality and Land Use Indices. The water quality condition was evaluated using a water quality index, and pesticides and pharmaceuticals were measured in water. The following biomarkers were analyzed in the fish: general health status (Condition Factor, Hepatosomatic index and energetic costs), enzymatic activity (GST, CAT, AchE), carbonyl content in proteins and histopathological responses in liver and gills. The most impacted sites by the presence of pesticides showed more alterations in the surrounding landscape; specially, changes in the riparian area. In this area, biomarkers denoted more damage than in sites with protected riparian zone. Conservation status of riparian ecosystems is crucial in the determination of rivers ecological quality. Our results demonstrate the importance of monitoring the environmental quality through an integrated analysis, using native fish to understand the effects of human activities on the biota.Graphical abstract: [ABSTRACT FROM AUTHOR]

A simple, inexpensive, versatile, and environment-friendly extraction method, using low-temperature partitioning extraction (LTPE), was validated to quantify pharmaceutical-active compounds (PhACs) in surface water samples by high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The PhACs analyzed were acetaminophen, bezafibrate, diclofenac, diltiazem, fluconazole, linezolid, miconazole, ondansetron hydrochloride, and trimethoprim. The detection and quantification limits ranged from 0.15 to 12.30 ng L−1 and 0.43 to 40.60 ng L−1, respectively. Recovery rates ranged from 46 to 135%, and relative standard deviation (RSD%) varied between 0.49 and 6.13%. This method was applied to monitor water contamination by PhACs in the Paraopeba River Basin (PRB), Minas Gerais state, Brazil. All PhACs, except linezolid which was not detected, were found in PRB water samples in concentrations that ranged from 2.6 ng L−1 to 2.62 μg L−1. [ABSTRACT FROM AUTHOR]

Cryptosporidium and Giardia are associated with cases of water and foodborne outbreaks in the world. This study included 50 samples of surface raw water collected from two watersheds in the state of São Paulo, Brazil. The isolation of (oo)cysts was performed in accordance with the U.S. Environmental Protection Agency’s methods 1623 and genotypic characterization and quantification were carried out by Nested PCR and qPCR assays based on 18S rRNA and gdh genes, respectively. U.S. EPA 1623 method showed the presence of (oo)cysts in 40% (x¯ = 0.10 oocysts/L) and 100% (x¯ = 7.6 cysts/L) of samples from São Lourenço River, respectively, and 24% (x¯ = 0.8 oocysts/L) and 60% (x¯ = 1.64 cysts/L) of Guarapiranga Reservoir, respectively. The qPCR assay detected C. hominis/parvum in 52% (0.06 to 1.85 oocysts/L) of São Lourenço River and 64% (0.09 to 1.4 oocysts/L) of Guarapiranga Reservoir samples. Presence/absence test for Giardia intestinalis was positive in 92% of São Lourenço River and 8% of Guarapiranga Reservoir samples. The assemblage A was detected in 16% (0.58 to 2.67 cysts/L) in São Lourenço River and no positive samples were obtained for assemblage B in both water bodies. The characterization of anthroponotic species C. parvum/hominis, G. intestinalis, and assemblage A was valuable in the investigation of possible sources of contamination in the watersheds studied confirming the need of expanding environmental monitoring measures for protection of these water sources in our country. [ABSTRACT FROM AUTHOR]

Waters entering the small estuaries of the Brazilian north-east originate from drainage basins that cross semi-arid and tropical rainforest areas at various levels of use and conservation. Such rivers are often under heavy demand for water supply and other services, such as effluent dilution. The present study examines four consecutive years (2006-2009) of water quality-monitoring data divided by season (rainy and dry) just before the Goiana River enters its estuary. The environmental variables are largely controlled by rainfall patterns. The water temperatures are consistently above 25 °C, which impairs dissolved oxygen levels (3.1 to 6.7 mg L) and may suggest eutrophication. By contrast, biochemical oxygen demand, percentage O saturation and total phosphorous (which are eutrophication indicators) do not show non-compliant levels, according to local legislation. Although the monitoring stations surround a municipal centre, the estuary is downstream from this area, the main uses of which are artisanal fisheries, nature conservation, leisure and aquaculture. Therefore, continuous monitoring and long-term analysis of the resulting water quality are important. [ABSTRACT FROM AUTHOR]