Ambiente e Agua - An Interdisciplinary Journal of Applied Science

Evaluation of the aerobic process performance for treating tannery effluent in the fungicide presence and ammoniacal nitrogen high concentration

2025-01-10T18:57:41-03:00

Leather processing is characterized by the generation of effluents with a high concentration of ammonia nitrogen (N-NH4+) and the presence of fungicides. This study evaluated the interference of these two constituents on the removal of chemical oxygen demand (COD) and N-NH4+. To this end, an aerated reactor operating in a batch system was used. The effects of cycle time, fungicide volume, and initial N-NH4+ concentration on COD and N-NH4+ removal was evaluated using a Centralized Rotational Composite Design. The highest COD removal (45.45%) occurred under the conditions of 72 h, 0.55 mL of fungicide, and 62.5 mg L-1 of N-NH4+, and the lowest removal (8.24%) occurred under the conditions of 24 h, 0.28 mL of fungicide and 84.8 mg L-1 of N-NH4+. The highest removal of N-NH4+ (38.49%) occurred under the conditions of 42 h, 0.55 mL of fungicide, and 62.5 mg L-1 of N-NH4+, and the lowest removal (4.26%) occurred under the conditions of 24.1 h, 0.82 mL of fungicide and 84.8 mg L-1 of N-NH4+. Through statistical analysis, it was possible to obtain mathematical models for the two response variables, which satisfactorily described the removal efficiency of COD and N-NH4+, and through the desirability analysis, it was possible to optimize the treatment process operation with a cycle time of 58.15h, with the addition of 0.62 mL of fungicide and 57.91 mg L-1 of ammoniacal nitrogen. Although the removal of N-NH4+ via nitrification is an efficient technique in industrial effluent treatment, the results obtained in this work indicate that the removal of N-NH4+ was significantly affected by the presence of the fungicide. Keywords: biological treatment, chemical oxygen demand, DCCR, TCMTB.

Optimizing COD reduction in dairy wastewater treatment using magnetic coagulant derived from Moringa oleifera

2025-01-14T01:55:18-03:00

In wastewater treatment scenarios, traditional coagulants are becoming increasingly complex and raising environmental concerns. This has led to the exploration of magnetized plant-derived coagulant as an alternative. In this paper, coagulation parameters such as coagulant dosage and pH were optimized through response surface methodology (RSM) based on a central composite design (CCD) employing a magnetic coagulant derived from Moringa oleifera seeds (M. oleifera–CoFe₂O₄). The optimized response variable during the treatment of dairy wastewater was the chemical oxygen demand (COD) reduction. The response surface methodology revealed a statistically significant second-order polynomial model (R² 99.24%) for maximizing COD reduction. The maximum COD reduction achieved was 76.13% under optimal conditions with coagulant dosage of 14.24 g/L and pH of 9.38. The results indicated that magnetic coagulant derived from M. oleifera seeds demonstrated significant potential and can be used in an efficient and eco-friendly process for dairy wastewater treatment.

Keywords: coagulation, dairy wastewater, flocculation, magnetic coagulant, Moringa Oleifera.

Biochar from orange waste as a filter medium for domestic effluent treatment aimed at agricultural reuse

2025-01-14T01:56:03-03:00

Brazil is the world's leading orange grower, and this agro-industrial sector produces a sizable amount of by-products. Because biochar has the potential to be used as a filtering medium in wastewater treatment systems, it can be advantageous to produce biochar from orange trash as an efficient way to use these resources. The purpose of this study was to assess how temperature affects the synthesis of biochar and to describe the adsorptive qualities of the material for use in filtration systems for agricultural reuse. The produced material was examined for its chemical composition, crystalline structure, morphological changes brought about by the conversion of biomass into biochar, surface area, and average pore size. The pyrolysis temperatures used to produce biochar ranged from 350 to 650°C for 60 minutes. Based on the advantageous physicochemical characteristics for usage as an adsorbent, 550°C was determined to be the ideal temperature. The orange biochar system outperformed the gravel system in terms of macronutrient removal, according to the filtration results using septic tank effluent. The elimination of magnesium (62.09%) and total phosphorus (31.58%) was noteworthy. These findings indicate a promising and long-term wastewater treatment option by indicating that the treated effluent may be suitable for use in some crops.

Keywords: biochar, horizontal flow, sewage treatment, wastewater.

Monitoring deposition and resuspension of the iron ore tailings in the Doce River after the Fundão Dam rupture

2025-01-14T01:56:31-03:00

The Doce River, located in Southeast Brazil, is of great importance in supplying water for urban use, agriculture, fishing and other purposes. It was affected by a disaster that occurred on November 5, 2015 due to the collapse of the Fundão ore tailing dam, in the municipality of Mariana (MG). This disaster generated socio-environmental consequences, as some regions were severely affected due to the waste released in the river, which was considered potentially toxic in the short to long term. This work presents a temporal analysis of images from the Landsat 8 satellite, associating the aspects of rainfall in dry and rainy months, in years before and after the disaster (2014, 2015, 2016, and 2020), together with the Normalized Difference Water Index (NDWI) obtained by image digital processing, to analyze the relation between dry and rainy periods and the spectral response of images. This analysis allowed the understanding of the behavior of the suspended materials, before and after the disaster, to unravel how the dispersion of tailings occurs. Part of the ore tailing that was deposited along the river went into suspension again in the rainy season one year after the disaster and, five years after, the satellite images show no difference compared to pre-disaster conditions. But, seven years after the spill, there are still iron ore tailings deposited and mixed with the river sediments. The fluvial dynamics are incorporating the tailings into the sediments, originating conducive places to provide various types of metals adhered to the particulate matter.

Keywords: iron ore tailings, rainfall, remote sensing.

Morphophysiology of yellow passion-fruit seedlings cultivated with macrophyte (Eichhornia Crassipes) under salt stress

2025-01-14T01:56:44-03:00

The use of aquatic macrophyte biomass could be a viable alternative for producing substrates. The objective was to evaluate the production of yellow passion fruit seedlings in different macrophyte-based substrates under salinity stress. The experiment was carried out at the Seedling Production Unit in Redenção, Ceará state. A completely randomized design was used, in a 2 × 5 factorial arrangement, with respect to two electrical conductivities of irrigation water (0.8 and 2.5 dS m^-1) and five substrates (S1 = 54% soil + 29. 5% sand + 16% macrophyte; S2 = 34% soil + 33% sand + 33% macrophyte; S3 = 24% soil + 26.5% sand + 49.5% macrophyte; S4 = 20% soil + 14% sand + 66% macrophyte; and S5 = 10% soil + 7.5% sand + 85.5% macrophyte), with 10 replications. Salt stress negatively affected photosynthesis, transpiration, stomatal conductance and internal CO₂ concentration of yellow passion-fruit seedlings. The use of S1 (54% soil + 29.5% sand + 16.5% macrophyte) was more efficient for plant height, leaf area, shoot dry mass, root dry mass, and total dry mass, while S5 (10% soil + 7.5% sand + 82.5% macrophyte) provided higher photosynthesis in yellow passion fruit seedlings. Substrate 1 (54% soil + 29.5% sand + 16.5% macrophyte) and S3 (24% soil + 26.5% sand + 49.5% macrophyte) alleviated salinity stress on Dickson quality index and stem diameter. The use of macrophytes has been shown to be beneficial in the production of passion fruit seedlings, with positive effects on development and gas exchange, and alleviation of salt stress.

Keywords: aquatic plant, Passiflora edulis, salinity, substrate.

Sustainability, social inclusion, and governance: analyzing ESG practices at an urban public university in São Paulo, Brazil

2025-01-14T01:56:51-03:00

The growing global emphasis on environmental, social and governance (ESG) principles has driven higher education institutions to adopt more sustainable and socially inclusive practices. However, a lack of metrics and regular reporting often limits the ability to assess the true impact of these initiatives. This study critically examined ESG practices at a public urban university in São Paulo, focusing on the Department of Agricultural Sciences (DAS). Using a case study approach, the research employed a systematic literature review, document analysis and on-site observations to assess how ESG principles are implemented. Correspondence Factor Analysis (CFA) and Discursive Textual Analysis (DTA) were used to identify patterns and insights. The findings highlight the University's commitment to sustainability and social inclusion, particularly through initiatives such as the Accessibility Assurance Plan (PGA) and environmental conservation efforts. However, the study also identified the need for structured evaluation metrics and more transparent reporting to better monitor the impact of these initiatives. The research concludes by suggesting that future studies should explore how ESG practices influence students' perceptions of educational quality and examine the financial costs and benefits of these initiatives to guide more strategic implementation in higher education institutions.

Keywords: environment, equity, policies, social inclusion.

Effects of human disturbance gradient on aquatic macroinvertebrate diversity: A study in a river of the Sierra Nevada de Santa Marta

2025-01-29T14:53:32-03:00

Understanding the environmental factors that shape macroinvertebrate diversity is particularly important because rivers in the neotropics are continuously affected by changes in land use. The main objective of this work was to analyze how environmental variables associated with different levels of human activity shape the macroinvertebrate community in the Ranchería River. Various environmental variables were measured at each of the nine sampling stations distributed across three gradients of human activity in the Ranchería River Basin. The sampling design included three stations in the high elevation zone (P9, P8, P7; 595 to 308 masl), three in the medium elevation zone (P6, P5, P4; 153 to 112 masl), and three in the low elevation zone (P3, P2, P1; 90 to 22 masl). For aquatic macroinvertebrates, five monthly samples were taken from January to May 2010 from these nine stations. A total of 4,615 individuals were collected, distributed across 16 orders, 54 families, and 83 taxa. The taxa with the highest relative abundance were Simulium (Diptera), Melanoides sp. (Thiaridae), and Orthocladiinae (Diptera: Chironomidae), with 20, 11, and 9% respectively. It was found that anthropogenic impacts shape the environmental variables and the structure of macroinvertebrate communities in the Ranchería River Basin.

Keywords: anthropic affectations, canonical correspondence analysis, Hill numbers, Rancheria River, Sierra Nevada de Santa Marta.

Treatment of dairy cattle farming wastewater using constructed wetland system cultivated with rice

2025-01-29T14:57:57-03:00

The amount of waste produced each day by dairy cattle is one of the largest problems in intensive management systems. Therefore, disposing of residues from animal facilities has become a challenge for farmers and specialists due to its technical, sanitary, and economic aspects. Organic effluents from confined dairy production systems require proper dairy wastewater treatment before disposal. When discharged into water bodies without adequate treatment, these effluents can cause physical and chemical changes in water sources, posing risks to public health and water supply due to the presence of pathogens and/or toxic elements. This study evaluates the efficiency of a constructed wetland system (CWS) cultivated with rice (Oryza sativa) in removing pollutants from dairy cattle wastewater, while also assessing the crop yield as an integral indicator of the system’s performance. Given the limited number of samples collected, the results presented should be considered as a preliminary analysis, providing insights into the system’s performance and potential for future studies. The constructed wetland system has a surface area of 4 m² and operates with a flow of 500 L dia^-1 and hydraulic retention time of 1.72 days; gravel was used as a support medium. The analyses conducted led to the conclusion that the constructed wetland system, cultivated with rice, demonstrated effective pollutant reduction, particularly excelling in the removal of organic matter (35%), turbidity (43%) and nitrite (36%). Rice cultivation showed adaptation to the constructed wetland system, exhibited satisfactory growth, and showed no signs of nutrient deficiency.

Keywords: biological treatment, cultivated beds, reuse, water resources.

Klebsiella pneumoniae isolated from the intestines of Tenebrio molitor larvae (Coleoptera: Tenebrionidae) that consume expanded polystyrene

2025-02-25T02:24:40-03:00

Plastics such as polystyrene are resistant to biodegradation, pollute the environment, and negatively impact the health of living organisms. However, several organisms, such as the larvae of Tenebrio molitor (Coleoptera: Tenebrionidae) and their associated gut microbiome, contribute to its degradation. The aim of this research was to determine the efficiency of degradation of expanded polystyrene (EPS) by gut bacteria isolated from larvae of T. molitor. To achieve this, a set of EPS-degrading bacteria was selected based on the time required to utilize the polymer as a carbon and energy source. Additionally, EPS degradation efficiency was compared, and the most efficient degrading bacterium was identified at the molecular level. Results showed that 95.13% of the bacteria isolated on nutrient agar and 86.57% of those isolated on MacConkey agar were able to grow on EPS. Five selected bacteria were able to degrade the polymer after 36 hours of incubation. The efficiency of EPS degradation, expressed as the percentage of weight loss by the degrading bacteria, ranged from 5.29% to 12.68%, with a reduction rate of 0.0005 to 0.0013 g per day and a half-life of 533.15 to 1386.20 days. Finally, 16S rRNA gene analysis identified the bacterium as Klebsiella pneumoniae. Cultivable gut bacteria from T. molitor larvae have demonstrated potential as candidates for EPS degradation, and biotechnological techniques can further enhance the efficiency of the degradation process.

Keywords: biotechnological techniques, gut microbiome, polystyrene degradation.

Suitable areas for Juçara palm (Euterpe edulis Martius) cultivation in Rio de Janeiro state, Brazil: proposal to encourage agro-ecological practices and non-timber products

2025-02-28T01:00:21-03:00

The Juçara palm (Euterpe edulis Mart.) is a native species of the Atlantic Forest biome, with high commercial value due to, among other uses, the extraction of the palm heart and pulp. This species has essential ecological interaction with fauna, providing food for many frugivorous species. However, it is on the list of endangered species, mainly due to the disorderly exploration of the palm tree for the extraction of the palm heart, but also due to climate change, habitat fragmentation, and defaunation. In this context, understanding which areas are suitable to grow this species is important for planning and supporting decision-making, as well as delimiting areas environmentally suitable according to the optimal requirements of species and land-use occupation. Our aim was to identify the suitable areas to cultivate Juçara palm in the State of Rio de Janeiro and provide a set of supporting maps and information for this productive sector, to increase agroforestry systems, or even for forest conservation and restoration purposes. Environmental parameters for the species (soil, elevation, air temperature and rainfall), and land use and land cover were assessed in order to perform the mapping of the optimal areas. The results indicate a potential for cultivation of Juçara palm in the State of Rio de Janeiro. All regions of the State have suitable areas, especially the Médio Vale do Paraíba, Centro–Sul, and Baixadas Litorâneas. The most restrictive variables to grow Juçara Palm in Rio de Janeiro State were rainfall and inadequate land use/cover for planting.

Keywords: environmentally suitable areas, geoprocessing, Juçara palm, planning.

Spatial and temporal distribution of potentially toxic elements in the urban area of São Raimundo Basin in Manaus, Brazil

2025-03-11T16:17:40-03:00

Contamination of surface water by metallic elements is an environmental concern in cities with industrial parks such as Manaus in Amazonas, Brazil. The concerns are related to the bioaccumulation of these elements and their toxicity, which affect the ecology of aquatic environments and human health. The study evaluated the role of seasonality in the concentrations of potentially toxic metals in the São Raimundo Basin in Manaus. Collections were carried out in June 2021, October 2021 and January 2022 at thirty collection points. The physicochemical parameters were analyzed according to the Methods for the Examination of Water and Wastewater of the APHA/AWWA. The metals were analyzed using optical emission spectrometry with inductively coupled plasma (ICP-OES), and the data using analysis of variance (ANOVA), Pearson correlation and Principal Component Analysis (PCA). All presented values outside those established by Brazilian legislation, with an average of 267.2 ug/L. ANOVA showed role of seasonality in the concentrations of the metals, with the periods of flooding in the basin having the lowest concentrations of metals. Such as Barium (Ba) and Beryllium (Be) with averages close to 0.0 ug/L in the flood period, and dry period with average values of 0.50 ug/L. The correlation showed the relationship of Ba, Be and Titanium (Ti) with the Biochemical Oxygen Demand (BOD). PCA indicated the metals Ba, Be and Ti as the most relevant contaminants in the basin. It was possible to develop a map to identify the sampling points where the concentrations of these metals are the highest.

Keywords: Surface water, toxic metals, urban basin, water contaminants.

Statistical characterization of a capacitive soil moisture probe, integrated into the water balance system in agriculture in a semi-arid region

2025-03-14T20:17:34-03:00

Soil water balance serves as a key indicator of moisture variability across the soil profile. Traditional instrumentation can significantly benefit from advancements in soil moisture monitoring technologies. The sensors can be integrated into precision irrigation systems. This study aimed to assess the water balance in a drainage lysimeter, integrated with a low-cost soil moisture monitoring system using the HD38 sensor. Soil moisture was tracked over a 50 cm depth using four capacitive probes. Environmental variables, including temperature and relative humidity, were monitored using a low-cost DHT11 thermo-hygrometer. Statistical analyses highlighted the dynamics of the water balance and sensor at various depths, with a particular focus on the sensor installed near the soil surface.

Keywords: Arduino, irrigation, Pearson correlation, probe, soil moisture.

Influence of land use on benthic macroinvertebrate assemblages in headwater streams of the Jaguari River Basin, Brazil

2025-03-24T23:36:28-03:00

Headwater streams play a crucial role in the formation of rivers; they boast numerous springs and serve as hotspots for aquatic biodiversity within watersheds. However, human activities frequently compromise the health of these environments. Common disturbances include the removal of riparian vegetation, sedimentation in the streambed, and the introduction of pollutants such as pesticides. This study sought to assess the macrobenthic community in three headwater rivers over a 9-month period, examining variations in water quality and community composition across different land uses. Key water quality variables — electrical conductivity and total suspended solids — were elevated at the Extrema (EX) Stream, likely attributable to pasture management practices. The Toledo (TO) Stream had higher water temperature and phosphate levels, potentially linked to the removal of riparian forest and the use of fertilizers in vegetable cultivation, respectively. Regarding the benthic community, metrics such as dominance (D); the percentage of Ephemeroptera, Plecoptera, and Trichoptera (% EPT); the EPT/Chironomidae ratio; and the Shannon–Wiener diversity index (H') revealed a clear gradient in environmental health among the three study sites. The Monte Verde (MV) stream emerged as the most pristine one, followed by the EX and TO sites. These data underscore the deleterious impact of unsustainable agricultural practices. In conclusion, such agricultural activities exert a negative influence on both environmental quality and benthic macroinvertebrate communities in headwater streams.

Keywords: biomonitoring, Camanducaia River, EPT, riparian vegetation.

Phosphorus fractions in different management systems in the Cerrado Goiano

2025-04-04T18:42:01-03:00

Phosphorus (P) is an essential macronutrient for plant development. Cerrado soils have a high P adsorption capacity, and conventional management can increase fixation, losses and reduce its availability in the soil. This study assesses the influence of different management practices on soil P fractions in cultivated areas in the Cerrado of Goiás. Deformed samples were collected at depths of 0-5 and 5-10 cm in two areas (Boa Vereda - BV and Mata do Lobo - ML). The total organic carbon content, pH, and phosphorus fractions (soluble, available, inorganic, organic, calcium-bound, occluded, and total) were quantified. The design was entirely randomized. Principal component analysis (PCA) was carried out. In BV, available and inorganic P levels were higher at 0-5 cm in the Cerrado area, while at 5-10 cm, available P was more prominent in soybean and Cerrado. The crop-livestock-forestry integration system showed high levels of occluded P. In ML, occluded P was predominant, except in the agroforestry system at 0-5 cm, where available, inorganic, calcium-bound, and total P levels were higher, while occluded and organic P levels were more prominent in soybean and pasture. At 5-10 cm, available P was lower in the cerrado, while occluded and total P levels were higher in soybean. The PCA confirmed the difference between the areas and management systems. Less intensive management systems promote higher levels of P fractions that are more available to plants.

Keywords: Cerrado crops, conservation systems, phosphorus lability, soil quality.

Morphochemical characterization and interactions of secondary microplastics with paracetamol and microalgae

2025-04-04T18:47:57-03:00

The morphochemical properties of microplastics influence their interactions with pollutants, biota, and toxicity. This study focused on the effects of microalgae exposure to secondary microplastics (SMP) derived from different plastic materials, often associated with pharmaceutical residues. Tetraselmis sp. were exposed to SMP alone and in combination with paracetamol. The SMP exhibited irregular morphology and sizes ranging from 8 to 1749 µm. morphochemical properties were analyzed using FTIR, SEM-EDS, and zeta potential. FTIR analysis identified three types of SMP (linear low-density polyethylene, polypropylene, and polystyrene), all showing a negative surface charge. Carbon, oxygen, calcium, chlorine, aluminum, bromine, and titanium were detected in all samples. Microalgae growth remained unaffected by SMP exposure, except at paracetamol concentrations of 400 and 500 mg.L^-1. The study suggests that the surface charge of SMPs significantly influences their toxicological effects. Furthermore, the resilience of microalgae to paracetamol and microplastics underscores their potential as bioindicators in microplastic-contaminated environments.

Keywords: morphochemical properties, paracetamol, secondary microplastic, Tetraselmis sp., toxicity interactions.

Natural coagulant for water treatment based on cationized tannins from Terminalia Catappa bark

2025-04-09T18:21:30-03:00

In a drinking water treatment plant, particles in the water must be destabilized in the coagulation stage after adding coagulants and performing intense stirring to remove impurities. Finding new alternatives to replace chemical coagulants and evaluating the turbidity and pH parameters to observe their effect on water treatment is essential to reduce costs and minimize environmental impacts. This study therefore aimed to develop and test a vegetable coagulant based on a tannin-rich extract of Terminalia catappa L. and to evaluate different coagulant concentrations at different stirring times. The extract was acquired from the tree bark for quantification and formulation of the coagulant. After this, the extract was cationized and employed in the coagulation test, with concentrations of 50, 100, 150, and 200 mg L^-1 and a chemical product as a comparison. Two different stirring times were performed (2 min followed by 10 min (T1) and 2 min and 20 min (T2). The turbidity and pH values were evaluated every 10 min up to 60 min. The data obtained were subjected to analysis of variance by Tukey's test at 5% probability to observe if there was a statistical difference. Terminalia catappa presented 10.01% of condensed tannin content. The natural coagulant treated the water efficiently. The best concentration found was 200 mg L^-1, with sedimentation of 30 min, and the best stirring time was T2. The coagulant reached the minimum turbidity values required by the Brazilian regulations for water for human consumption and did not alter the original water pH.

Keywords: forest species, phenolic compound, water quality.

Treatment of wastewater from a printing industry using electrocoagulation

2025-04-16T20:43:23-03:00

This study investigated the use of the electrocoagulation process in the treatment of wastewater generated from printing with graphic ink. The efficiency of the electrocoagulation process was assessed employing the following study variables in the experimental tests: electrolyte concentration (1 g L^-1 and 2 g L^-1), electric current intensity (2 A and 4 A), and stirring speed (400 rpm and 800 rpm). The experimental tests were conducted in a batch reactor with a monopolar parallel electrical connection for 30 min. The performance of the electrocoagulation process evinced a 76.54% reduction in COD, 96.09% turbidity removal and 76% color removal. The results obtained with the application of the acute toxicity tests with the freshwater microcrustacean Daphnia magna (Crustacea, Cladocera) revealed a considerable reduction of the toxicological risk of the printing ink wastewater stemming from the electrocoagulation process. The acute toxicity tests point to values in the range from 11.50% to 85.92% in terms of lethal concentration (LC₅₀) after 48 h of exposure of microcrustacean Daphnia magna. Comparatively, the lethal concentration for the wastewater stemming from the printing process with printing ink presented a value of 0.11%, indicating substantial sensitivity to the possible toxic compounds present in the wastewater.

Keywords: acute toxicity, COD, electrocoagulation, printing ink, wastewater.

Pesticide contamination of water for human consumption in Sergipe, Brazil (2014-2022)

2025-04-28T21:54:24-03:00

The presence of pesticides in drinking water is a growing concern worldwide. In Brazil, and especially in Sergipe, few studies evaluate pesticide contamination in rivers. The study assessed the presence of pesticides in water intended for human consumption in municipalities in Sergipe between 2014 and 2022. Information on pesticides was extracted from the Water Quality Monitoring System for Human Consumption (SISAGUA). To carry out the analysis of pesticide contamination in each municipality, the concentrations, absolute and relative frequency of pesticide occurrence, and the number of times the maximum allowed values (MAV) established by Brazilian and European legislation were exceeded were considered. Contaminated samples were found in 60% of the municipalities, of which 8.8% exceeded the MAV for Brazil and 80% for Europe. In 41 municipalities, the most common pesticides are classified as Class I (extremely toxic). Among the pesticides most frequently found in the samples, "DDT+DDD+DDE" stands out with concentrations 3.6 times above the MAV for Brazilian legislation. For European legislation, the pesticides that presented values above the established limits were 2,4D + 2,4,5T, Chlorpyrifos, Carbendazin, Glyphosate, Manconzeb, Methamidophos, Profenophos and Tebuconazole, which presented values between 35 and 92 times. The results of this study provide a comprehensive overview of pesticide contamination in water intended for human consumption in Sergipe and highlight the urgency and importance of effective control and monitoring measures to reduce contamination and protect the health of Sergipe’s population.

Keywords: public health, water for public supply, water quality.

From urban areas to conservation unities: assessing microplastic pollution across the Pantanal

2025-05-13T02:29:42-03:00

Microplastics are one of the most widespread problems that have drawn serious attention from researchers, policymakers and the public due to the potential ecological, environmental and human health implications. The objective was to verify the relationships between urbanization areas and microplastic contamination in selected freshwater locations. We estimate microplastic densities using a range of statistical analyses, including linear regression and distribution comparisons, considering two important factors: the distance from an urban center and the specific characteristics of the sites’ (e.g., spring, intermediate, mouth) the urban and rural contexts. Our findings indicate a statistically significant positive relationship between the effects of proximity to urban centers to microplastic density in the freshwater environments. In other words, the density of microplastics tends to increase with decreasing distances to urban areas, showing higher concentrations compared to rural sites. The influence of some specific environmental characteristics (water quality and biodiversity in general) is based on the accumulation of microplastics suggesting a complex interaction of anthropogenic activities and natural features. This, therefore, calls for local mitigation measures and changes in the ways waste is handled, especially in urban areas, put in place systematically to mitigate the underlying causes of microplastic pollution. Finally, our research underscores the importance of urban areas in microplastic pollution studies and the necessity of interventions to reduce plastic consumption and improve waste management practices. As part of this research on the issue of microplastic pollution, a future policy that supports the reduction of contamination by these pollutants in freshwater ecosystems is essential.

Keywords: density of microplastics, urban water, wetland.

Biological, physicochemical, and social impacts resulting from the rupture of the Fundão Dam

2025-05-15T00:05:58-03:00

Mining is essential to Brazil's economy; however, the collapse of the Fundão Dam on November 5, 2015, due to the improper deposition of tailings, released approximately 50 million cubic meters of tailings into the environment. This disaster, the largest in the Brazilian mining sector and one of the most significant globally, affected the Doce River and its ecosystem across over 650 kilometers to the Atlantic Ocean, causing extensive damage to biodiversity and contaminating the Atlantic Forest, estuaries, and coastal areas, with the risk of extinction for some species. Water quality was severely compromised, with increased levels of heavy metals and significant impacts on microbiota, flora, and aquatic fauna. The social and economic consequences were also severe, affecting mental health, fishing, and agriculture within local communities. Accordingly, this review article seeks to address the identified knowledge gaps by comprehensively examining the biological, physicochemical, and social impacts of the Fundão Dam collapse. The review also highlights the differences between pre- and post-disaster and discusses the inadequacy of the containment measures adopted. The conclusion is that mitigation efforts were insufficient and delayed, resulting in lasting and severe consequences for both the environment and the population, underscoring the need for more effective environmental protection in the mining sector.

Keywords: contamination, environmental impacts, mining.

The use of rainfall disaggregation coefficients to obtain intensity-duration-frequency curves: estimation using pluviographic data versus national mean values

2025-05-15T18:16:58-03:00

The lack of sub-daily rainfall data to obtain intensity-duration-frequency (IDF) relationships at a local scale is a common limitation in many countries. This study determines rainfall disaggregation coefficients using pluviographic data from several meteorological stations to adjust IDF curves for Rio de Janeiro state, Brazil. The adjusted IDF curves using the coefficients obtained show satisfactory adjustment with Nash and Sutcliffe efficiency values above 0.99 compared to the mean values proposed by Cetesb (1979). The root mean square error (RMSE) of the estimated rainfall intensities using the adjusted IDF relationships for different return periods and rainfall durations varied between 2.55 at the Eletrobrás station and 42.49 at the São Bento station. The disaggregation coefficients obtained for Rio de Janeiro state differ from the values proposed in the literature, which confirms the need to adjust values locally and for hydrologically homogeneous regions. This local and regional scale approach provides more accurate IDF curves.

Keywords: extreme rainfall, IDF relationship, Rio de Janeiro.

Integrated approach to assess water quality and risk assessment for aquatic biota in Baía Negra, Pantanal, Brazil

2025-05-20T00:53:50-03:00

The Baía Negra Environmental Protection Area, situated within the Pantanal Sul-Mato-Grossense (BNEPA), represents an important conservation unit subjected to considerable environmental pressures resulting from human activities, such as agriculture and mining. This study evaluated the impact of these activities on water quality and their toxicogenetic effects on native fish. Physicochemical parameters and metals (Cd, Pb, Cr, Ni, Fe, Mn, Cu and Zn) were analyzed in water and macrophytes (Eichhornia sp.) collected from three sites along the Paraguay River. A 20 km buffer zone was used to assess the composition and structure of the landscape in the BNEPA. The results showed that the concentrations of Cd, Pb, Cr, Ni, Fe and Cu exceeded the legal limits established by CONAMA N° 357/2005, with Fe levels reaching a threshold that poses a substantial risk to aquatic biota. Macrophytes accumulated high Fe concentrations, indicating bioavailability and potential trophic transfer. Genotoxic and mutagenic alterations, including nuclear abnormalities and micronuclei in fish erythrocytes, were observed, indicating chronic exposure to contaminants. These findings highlight the urgent need for long-term biomonitoring programs and regulatory measures to mitigate the environmental risks of metal contamination and protect biodiversity in the Pantanal.

Keywords: anthropogenic impacts, aquatic bioindicators, genotoxicity, Pantanal wetlands.

Physical and chemical indicators of soil quality in a mountain environment in the Atlantic Forest biome

2025-07-11T19:19:32-03:00

Agricultural sustainability is the ability of a system to produce food properly without damaging environmental conditions. Assessing the quality of the soil and its attributes informs its proper use without compromising ecosystems. This study analyzes the chemical and physical properties of soil at sites under different management in the mountainous region of the state of Rio de Janeiro, Brazil. Two cultivation areas were selected: tomato (Solanum lycopersicum L.) and corn (Zea mays L.) production and; secondary forest. Four samples were taken at a depth of 0-10 cm to assess pH in water, Al⁺³, Ca⁺², Mg⁺², P, K⁺, Na⁺, H+Al, carbon (C), particulate organic carbon (COP), organic carbon associated with minerals (COMA), total nitrogen content, carbon stock (SCS), carbon in the free light fraction (FLFC) and intra-aggregate light fraction (ILFC). The apparent density (AD), particle density (PD) and weighted average diameter (WAD) of the aggregates were characterized. High P contents were observed in the tomato area (125.78 to 502.03 mg kg^-1) and in the corn area (127.80 to 253.14 mg kg^-1), indicating excessive fertilization. As for BD, values of 1.25 Mg m^-3 and 1.60 Mg m^-3 were observed in the tomato and corn areas, respectively, which were higher than those observed in the forest area. It was noted that the management carried out in the cultivated areas is not promoting the accumulation of organic matter in the soil. Monitoring soil properties can help identify changes that impact on productivity and environmental quality.

Keywords: agricultural sustainability, environmental fragility, soil conservation.

Assessment of sediment grain size and hydraulic interactions in urban drainage systems: a case study from Juliaca, Peru

2025-07-11T19:32:00-03:00

Urban drainage systems are essential for the sustainability of cities, significantly impacting water management, pollution control, and urban planning. The city of Juliaca is characterized by a predominantly low slope, ranging from 0.0003 to 0.001 m m^–1, making it particularly susceptible to sedimentation processes within the existing drainage network. The objective of the research was to characterize the sediments in the stormwater drains and to assess the relationship between the granulometric properties and the hydraulic parameters of the drainage system. To achieve this, 12 sediment samples were collected from Zone D of Juliaca at the end of the rainy season and analyzed in the laboratory to determine the granulometric distributions and physical properties. Spearman's correlation coefficient was employed to establish the relationships between sediment characteristics and hydraulic parameters. The results revealed that the granulometric curves exhibited multimodal distributions. Sand was the predominant component in the samples, with an average content of 72.74%, followed by gravel at 21.36%, and silt and clay at 5.90%. The average particle size ranged from 0.159 to 2.132 mm. The drainage system was found to possess considerable hydraulic cross-sectional dimensions, with slope values ranging from 0.0004 to 0.031 m m^–1. The correlation analysis found both positive and negative relationships between particle-size distribution, sediment composition, and slope. However, these correlations were not entirely consistent with established sediment transport principles. This inconsistency is likely attributed to the influx of sediments into the drainage network from unpaved roads, driven by wash-off processes and surface erosion, among other contributing factors.

Keywords: critical velocity, granulometry, hydraulic parameters, unpaved roads, Urban drainage system

Irrigation with brackish water in the production of maize intercropped with peanut

2025-07-11T19:37:01-03:00

Integrating agricultural species with different tolerance levels to saline stress may be a promising strategy for biosaline agriculture. This study evaluates the agronomic performance of maize crops irrigated with brackish water and produced in a system integrated with peanut crops and monoculture. The experimental design used was randomized blocks arranged in a 5×2 factorial scheme with four blocks. The first factor corresponded to five levels of electrical conductivity of irrigation water: 1.0, 2.0, 3.0, 4.0, and 5.0 dS m^-1, and the second factor comprised two maize crop production systems: monoculture and integrated. The following variables were determined: ear length (EL, cm), ear diameter (ED, mm), unhusked ear mass (UEM, g) and husked ear mass (HEM, g), ear yield (Y, kg ha^-1), and water use efficiency (WUE, kg m^-3). Maize production in the monoculture system irrigated with water with a salinity of 1.0 dS m^-¹ was superior to the intercropping with peanuts in all variables analyzed. Saline stress caused by the increased electrical conductivity of irrigation water reduced productivity performance and water-use efficiency in maize crops, with significant severity in the monoculture system. Using the intercropping production system between maize and peanut crops is a promising alternative for cultivating these species in environments affected by salts, a strategy indicated for biosaline agriculture.

Keywords: Arachis hypogaea L., biosaline agriculture, cultivation systems, Zea mays L.

Impact of drilling waste and sludge on eucalyptus growth and soil and water quality

2025-07-22T23:57:01-03:00

The Brazilian forestry sector stands out for its eucalyptus production and the reuse of industrial waste to improve soil fertility. However, environmental monitoring in planting areas is important to assess potential contamination risks, with a focus on soil and water quality. Thus, the objective of this study was to evaluate the initial development of eucalyptus plants and the impacts on soil and water quality, as a function of different doses of the combined application of drill cuttings and sewage sludge. The morphological variables and quality parameters evaluated were: height, shoot and root biomass, crown and stem diameter, chlorophyll index, and concentration of nutrients and heavy metals in the soil and water. The levels of Ca, Mg, K, P, and N in the waste favored the nutrition of eucalyptus plants, but if not managed properly, they can affect soil quality. The same occurs for some metals such as Ba and Pb, which were found in high concentrations in the waste and require care. The water quality results show that some heavy metals in the drained water did not exceed the limits of Brazilian regulations, with the exception of Cu, Mn, Ni, Pb and Ba, whose high levels can be attributed to the composition of the waste. The use of gravel and sludge promoted improvements in plant development, but requires monitoring to avoid risks of soil and water contamination, especially with regard to heavy metals.

Keywords: environmental quality, reuse of waste, water resources, well gravel.

Using eco-friendly coagulants for biomass harvesting and water reuse in microalga cultivation

2025-07-29T00:30:26-03:00

The cultivation of microalgae is gaining prominence, but one of its main challenges lies in effectively harvesting the biomass and recovering the water used in the cultivation process. Addressing these issues is critical to minimizing environmental impacts and enhancing the sustainability of microalgae production systems. This study evaluates the efficiency of polyaluminum chloride (PAC) and a tannin-derived coagulant for harvesting Nannochloropsis oculata biomass, while also analyzing the potential for reusing the treated water. Microalgae were grown in a 5 L culture until a cell density of 10⁴ cells mL⁻¹ was achieved. After cultivation, samples were subjected to coagulation, flocculation, sedimentation, and filtration through a granular activated carbon system. An acute toxicity assessment was conducted using Daphnia magna as a bioindicator to determine the safety of the recovered water. Both coagulants demonstrated over 98% removal efficiency for suspended solids, turbidity, chemical oxygen demand (COD), and biochemical oxygen demand (BOD). PAC, at a concentration of 50 mg L⁻¹, yielded higher water quality than the tannin-based coagulant, which required 150 mg L⁻¹ for optimal performance. Furthermore, the treated water met international standards for irrigation in non-food crops. Toxicity testing confirmed that the treated effluent was non-toxic, making both coagulants suitable for microalgae harvesting, with PAC offering a more efficient option for water quality enhancement and lower chemical consumption.

Keywords: biomass harvesting, Nannochloropsis oculate., polyaluminum chloride, tannin-based coagulant, water reuse.

Development of an electrochemical sensor to determine amoxicillin in natural water based on CORE-SHELL/PVP

2025-10-07T16:10:58-03:00

In 2020, the world was affected by a new virus, SARS-CoV-2, which causes the disease known as COVID-19. Given the damage caused by the pandemic, there was a significant increase in the use of antibiotics. However, this increase causes harmful effects due to disposal in sewage systems by human and animal excretion and their manufacturing process. These drugs reach water resources, causing environmental impacts and damage. Given this current and worrying scenario, the focus of this work was to develop an alternative and lower-cost method for the detection of amoxicillin in natural urban waters, using an electrochemical sensor based on a core-shell formed by Fe₃O₄@Ag coated with the polymer polyvinylpyrrolidone. The device presented a wide linear range between 136 and 8210 µmol L^-1 of amoxicillin, with a detection limit of 7.8 µmol L^-1. When applied to detect the analyte in urban natural water samples and in commercial drugs, it presented a low relative error of 2.7% and 5.1%, respectively. Thus, the device proved to be an excellent alternative for detecting antibiotics in real samples, in addition to being miniaturized, allowing low-cost field analysis.

Keywords: amoxicillin, emerging pollutant, Fe₃O₄@Ag core-shell.

Effect of voltage and pH on the electrocoagulation process for chemical oxygen demand removal in wastewater from Mollendo, Peru

2025-10-24T10:48:47-03:00

The discharge of urban wastewater to receiving bodies represents a growing environmental threat in cities such as Mollendo, Peru, where the absence of a treatment plant has caused the discharge of untreated effluents into the sea, causing a serious ecological impact. Therefore, the objective of this study is to evaluate the influence of voltage and pH on the electrocoagulation process for the removal of Chemical Oxygen Demand (COD), whose initial concentration is approximately 670 mgL^-1. A system of 5 L batch reactors with iron electrodes was used, which presented fast removal kinetics, achieving a 94.4% reduction of COD in only 20 minutes under optimal conditions (pH 7.5 and 7 V) complying with local regulations. The rate constant around 0.1204 min^-1 indicates a high level of accuracy of the mathematical model. In addition, the operating cost was estimated at 0.3919 USD/Kg COD which corresponds to energy consumption of 0.363 USD/Kg COD. These results demonstrate the potential of electrocoagulation as an effective, economical and sustainable alternative to mitigate water pollution in coastal urban environments.

Keywords: electrocoagulation, pH, removal, time, voltage, wastewater.

Systematic review of green nanotechnology in the Andes: nanoparticle biosynthesis and applications from Chara globularis

2025-10-14T17:19:30-03:00

Chara globularis, a submerged macroalga widely distributed in the smaller Lake of Titicaca, covers approximately 436 km² over 60% of the vegetated lakebed—forming dense underwater meadows between 5 and 10 meters deep. Its ecological relevance lies in its ability to precipitate calcium carbonate and co-precipitate phosphorus, improving water clarity and modulating nutrient cycling in high-altitude oligotrophic environments. Beyond its ecosystem functions, C. globularis has emerged as a promising bioresource for the green synthesis of metal nanoparticles, offering a sustainable and low-cost alternative to conventional methods. Phytochemical-rich extracts from C. globularis are used to synthesize copper, silver, and gold nanoparticles, with visual colour changes indicating nanoparticle synthesis brown for copper nanoparticles (CuNPs), reddish-brown for silver nanoparticles (AgNPs), and ruby-pink for gold nanoparticles (AuNPs). These biogenic nanoparticles exhibited high stability and functional surface groups, as confirmed by Fourier Transform Infrared Spectroscopy (FTIR), Dynamic Light Scattering (DLS), and X-ray Diffraction (XRD) analyses. Their nanoscale size (typically 10–80 nm) and biocompatibility make them suitable for diverse applications in biomedicine (antimicrobial and anticancer therapy), agriculture (nanofertilizers and pest control), and environmental remediation (wastewater treatment and heavy metal removal). This study underscores the dual value of C. globularis as both a keystone species in Andean aquatic ecosystems and a platform for eco-innovative nanotechnology. The successful integration of native biodiversity with advanced material science not only promotes clean technology but also repositions C. globularis as a strategic natural resource for the sustainable development of high-altitude regions like Lake Titicaca.

Keywords: green synthesis, macroalga, macrophyte, nanostructures.

Use of Fava d'Anta extract in maize cultivation under saline stress

2025-10-14T17:19:32-03:00

Extract of Fava d’Anta (Dimorphandra mollis Benth) alleviates the deleterious effects of saline water. This study evaluates gas exchange and the initial growth of maize under saline stress and the use of Fava d’Anta extract. The experimental design was a randomized block design in a 5 × 4 factorial scheme with three replications. The first factor consisted of five levels of electrical conductivity of irrigation water (ECw = 1.0, 1.5, 3.0, 4.0, and 5.0 dS m⁻¹), and the second factor consisted of four foliar application frequencies of Fava d’Anta extract: F1 – no application; F2 – application every 10 days; F3 – application every 5 days; and F4 – daily application. Increasing salinity of the irrigation water reduced plant height, stem diameter, photosynthesis, stomatal conductance, transpiration, shoot dry mass, and root dry mass. The different application frequencies of the Fava d’Anta extract influenced plant height, photosynthesis, and shoot dry mass. Interactive effects were observed, with better results for the combinations S2 × F2, S3 × F2, and S3 × F2 for photosynthesis, stomatal conductance, and transpiration, respectively. These findings indicate that foliar application of Fava d’Anta extract every 10 days during the vegetative stage has the potential to mitigate the deleterious effects of saline water on maize. Daily application of the extract mitigated the harmful effects of irrigation water with EC of 4.0 dS m⁻¹ on gas exchange parameters.

Keywords: Dimorphandra mollis Benth, salinity, Zea mays L.

Hydrogeochemical modeling and groundwater quality in coastal aquifers in Northeastern Brazil

2025-10-24T10:45:36-03:00

Geochemical modeling is a central approach in hydrogeochemical assessments, enabling the identification of water-rock equilibrium conditions through mineral saturation indices and thereby increasing understanding of processes that control the chemical characteristics of groundwater. This study identified the main mechanisms governing hydrogeochemical behavior and evaluated the equilibrium conditions of the mineral species that comprise the hydrogeological framework of the northeastern coast of Brazil, using geochemical modeling to infer the processes controlling compositional and qualitative aspects from groundwater potable standards. The results indicate a predominance of sodium-chloride waters with concentrations of total dissolved solids, chloride, total hardness, sulfate, sodium, total iron, nitrate, turbidity, barium, and lead outside potable standards. Weathering induced by the interaction between groundwater and minerals of the infiltrated aquifers emerges as the principal hydrogeochemical control factor in the area. Geochemical modeling shows supersaturation for quartz, goethite, and hematite, and subsaturation for kaolinite, muscovite, illite, and calcite in the analyzed samples, explaining the high concentrations of elements from minerals prone to dissolution and the consequent addition of ions to solution, as well as the low concentrations of elements from minerals prone to precipitation, which are removed from solution. It is concluded that silicate weathering and carbonate dissolution are the main processes controlling the compositional state of groundwater in the region, with contributions from anthropogenic activities and marine influence.

Keywords: contamination, Gibbs diagram, phreeqc, Potiguar Basin.

Water quality inequalities in Brazilian municipalities: surveillance challenges for the 21st century

2025-11-18T22:14:55-03:00

Surveillance is the main strategy to ensure water quality. This study aimed to analyze the basic water quality parameters in Brazilian municipalities in 2018 according to their demographic, socioeconomic and geographic characteristics in order to explore the challenges of surveillance for the 21st century. We conducted a cross-sectional ecological study using official data from the Information System for Water Quality Surveillance for Human Consumption. More than 420K records from water supply systems across all 5,570 municipalities were submitted to a data cleaning and validation protocol processed with RStudio software. Variables included turbidity, free residual chlorine, pH, fluoride concentration, and the absence of Escherichia coli. Municipalities were categorized by population size, Human Development Index, and macro-region. The percentage of municipalities with valid information and compliance with expected standards was calculated based on institutional and scientific criteria. The results showed that E. coli and turbidity yielded the best performance (more than 75% of the municipalities had valid information) while pH and fluoride, the worst (less than 50% of the municipalities). In relation to the conformity, among municipalities with validated information, 80% or more were compliant with expected patterns for turbidity, free residual chlorine and pH and about half for E. coli and fluoride. In conclusion, the water quality surveillance was well implemented in one at each five Brazilian municipalities with significant differences according to demographic, socioeconomic and geographic characteristics of the municipalities.

Keywords: public health surveillance, public policy, water quality standards, water supply.

Performance analysis and spatial modeling for the use of Eichhornia crassipes in tertiary phosphorus removal from swine slaughterhouse effluents

2025-11-19T19:47:25-03:00

Eutrophication caused by phosphorus-rich agro-industrial effluents poses a major environmental and regulatory challenge, particularly in areas with limited wastewater treatment infrastructure. This study provides one of the first technical and environmental feasibility assessments of using Eichhornia crassipes as a complementary tertiary stage in swine slaughterhouse wastewater treatment plants. Based on operational data from a functioning treatment plant and an estimated phosphorus uptake rate of 0.000374 kg TP m⁻² d⁻¹, a performance analysis was conducted to evaluate phosphorus removal efficiency and compliance with discharge standards. Spatial modeling projected the surface area required to remove up to 7.08 kg TP d⁻¹, identifying an operational equilibrium at 6.02 kg d⁻¹. At this point, a biomass density of 10 kg m⁻² would ensure compliance with commonly referenced discharge standards (5 mg L⁻¹), requiring approximately 16,000 m². Scenarios involving spatial constraints and biomass reduction were assessed, along with potential mitigation strategies. A SWOT analysis was also conducted, addressing operational, environmental, and governance-related factors. The findings suggest that E. crassipes may serve as a viable complementary option with potential for cost efficiency in agro-industrial settings with available space, provided that appropriate harvesting, oxygenation, and monitoring practices are implemented, and pending confirmation through pilot‑scale validation under site‑specific conditions.

Keywords: Eichhornia crassipes, performance analysis, phosphorus removal, phytoremediation, swine slaughterhouse effluents.

Efficiency of a biodigester septic tank in sewage treatment and agricultural reuse in forage palm cultivation

2025-11-18T22:17:41-03:00

This study evaluated the efficiency of a biodigester septic tank (BST) in treating domestic sewage and investigated the effects of reusing treated effluents on forage cactus cultivation. The performance of the BST was observed through the physicochemical and microbiological parameters of the influents and effluents. Forage cactus irrigation was carried out with different proportions of treated domestic sewage effluent (TDWE) and rainwater (RWA): 0:100% (T1), 25:75% (T2), 50:50% (T3), 75:25% (T4), 100:0% (T5) (TDWE:RWA), and Tc (10% RWA). Soil analysis was performed before and after planting to verify the effect of the tested treatments on the soil. Biometric analyses of the crop were performed throughout the growing cycle, in addition to water response indices (WRI). The experimental design was completely randomized with three replicates. The BST demonstrated efficiency in treating domestic sewage, generating effluent of adequate quality for agricultural reuse. Treatment T5, with 100% treated effluent, may have caused nutritional imbalance, since the best crop development was observed in T4 (75% TDWE and 25% RWA), suggesting that dilution favored the agronomic performance of the forage cactus. Therefore, the results demonstrate the technical viability of the BST system effluent as an alternative source of water and nutritional input for forage cactus cultivation.

Keywords: agricultural reuse, cactus, effluent.

Influence of siltation on flood propagation: hydrodynamic analysis and hazard index assessment in the Jundiaí River Basin

2025-11-18T22:15:12-03:00

Siltation is one of the main aggravating factors for floods in urbanized basins, altering flow capacity and increasing socio-environmental risks. This study evaluates the impacts of siltation on flood dynamics in the Jundiaí River Basin (São Paulo, Brazil), using hydrodynamic modeling (HEC-RAS 6.0) and the Hazard Index (HI = y × v), based on hydraulic thresholds established in the literature. Three scenarios were simulated for an extreme 100-year return period (RP) event: (1) reference condition (no siltation), (2) moderate siltation (20% reduction in depth), and (3) severe siltation (40% reduction). The results indicated three distinct hydrodynamic behavior patterns: high-energy zones (where the cross-section reduction increased velocity and erosive power), active deposition zones (locations with low velocity, v < 0.3 m/s, with lateral flood expansion), and transition areas (with unstable Hazard Index behavior). An increase in the flooded area was observed by 12% (moderate scenario) and 28% (severe scenario), with a critical rise in the HI (> 4.0 m²/s) in high hydraulic energy zones, while low-velocity areas (v < 0.3 m/s) showed lateral flood expansion. Sediment deposition was predominant in floodplains and reaches with slopes < 0.3%, corroborating literature studies. It is concluded that siltation not only expands the flooded area but also intensifies hydrodynamic risks in critical regions, demanding integrated sediment management strategies.

Keywords: hazard index, hydrodynamic modeling, Jundiaí River, siltation.

Seasonal dynamics of litterfall nutrients in a native Brazil nut stand in the Tapajós National Forest, Eastern Amazon

2025-11-18T22:15:27-03:00

This study quantified carbon (C), nitrogen (N), and sulfur (S) concentrations in the litterfall of a native Brazil nut (Bertholletia excelsa) stand in the Tapajós National Forest, Belterra (Pará, Brazil), across dry and wet seasons. Monthly collections were conducted from August 2015 to July 2016 within a permanent plot of the MapCast Project, using 12 circular litter traps (0.25 m² each) systematically distributed in the forest. Litterfall was separated into leaves, flowers and fruits, wood, and miscellaneous fractions. After drying and sorting, samples were analyzed for C, N, and S contents using an elemental analyzer (CHNS/O). Seasonal patterns in elemental composition were observed: higher N and S concentrations occurred during the wet season, particularly in the miscellaneous fraction, whereas C was more abundant in the dry season, especially in leaves. Nevertheless, differences between seasons were not statistically significant (t-test, p ≤ 0.05). Significant correlations between nutrient contents and climatic variables (precipitation and temperature) were detected, emphasizing the responsiveness of litterfall to environmental variation. Overall, the results demonstrate that litterfall acts as a key reservoir and pathway for nutrient transfer in Brazil nut-dominated Amazonian forests, contributing to nutrient cycling and sustaining soil fertility. The persistence of litter on the soil surface plays an essential role in conserving edaphic fertility and supporting ecological stability. These findings provide valuable insights for forest management and conservation practices, while also advancing the understanding of biogeochemical processes that regulate the functioning and resilience of tropical ecosystems.

Keywords: cycling, fertility, forest.

Sediment dynamics in a semiarid catchment with cascade dam failures

2025-11-18T22:15:44-03:00

The research estimates the risks of cascade dam failures in a network of fifteen reservoirs in the Nogueira River Basin and their effects on sediment mobilization from the dam embankments. The runoff simulation was performed using the HEC-HMS model for the IDF curve of the Pentecoste meteorological station and different return periods. The hydraulic modeling of the cascade dam failure was performed using HEC-RAS. The results indicate that high flows with return periods exceeding 100 years can result in cascade dam failures. In the most extreme flood event, with a return period of 10,000 years, thirteen dams would fail, mobilizing substantial amounts of water and sediments. The results also highlight the ability of larger reservoirs to attenuate flood waves resulting from the failure of smaller dams located downstream. Nevertheless, they are still subject to failure during more extreme events (1,000 and 10,000 years). Regarding sediment dynamics, the results show significant sediment mobilization from the dam embankments during cascade dam failures. In the simulation for the 10,000-year return period, sediment erosion from dam embankments is observed to be thirteen times greater than that produced in the river basin, with negative impacts downstream. The effects of cascade dam failures on sediment dynamics are also analyzed in terms of average sediment concentrations at the reservoir inlet and outlet. The results indicate abrupt changes in the values of this variable due to the large amount of sediments eroded from the dam embankments and transported downstream in the reservoir network.

Keywords: breach formation, cascading dam failure, flood events.

Swimming pools as emerging environmental reservoirs of antimicrobial-resistant bacteria in two cities of southwestern Colombia: Cali and Jamundí

2025-11-24T22:20:22-03:00

Antimicrobial-resistant microorganisms are considered emerging environmental contaminants, and chlorination could exacerbate this issue. The main objective of this study was to characterize the antibiotic resistance profile of bacteria isolated from swimming pools in Cali and Jamundí, two cities in the southwest of Colombia. A total of 16 swimming pool water samples were microbiologically analyzed to determine bacterial diversity and assess antibiotic susceptibility to ten broad-spectrum antibiotics using the disk diffusion method. Bacterial isolates showing resistance were identified through 16S rRNA gene sequencing and selective differential growth media. A total of 69% of swimming pool samples did not comply with Colombian microbiological regulations. Among the bacterial isolates, 92% exhibited resistance to at least one antibiotic, with no significant differences between Gram-positive and Gram-negative species. Clinically relevant multidrug-resistant strains were identified, including Escherichia coli, Pseudomonas otitidis, Staphylococcus warneri, Proteus mirabilis, and Bacillus cereus, some of which showed simultaneous resistance to critical antibiotics such as tetracycline, ceftriaxone, vancomycin, and kanamycin. These results confirm that swimming pools provide a favorable environment for the presence of bacterial resistance. From a One Health perspective, these results emphasize the interconnectedness of human, animal, and environmental health, reinforcing the need for stricter monitoring and control of recreational waters to mitigate the spread of antibiotic resistance.

Keywords: one health, recreational water, waterborne pathogens.

Oxidation, coagulation and filtration processes for the removal of sulfides and organic matter from the effluents of a tannery

2025-11-24T22:20:41-03:00

Currently, the tanneries in the Río Seco Industrial Park discharge their liquid effluents into the sewer system, which then flows into the Añashuayco Stream, passing through nearby settlements, the Sillar tourist route, and agricultural areas. Finally, it enters the Chili River via the San Jacinto Stream, impacting agriculture in the lower Chili River Basin. In response to this problem, an alternative study is underway to achieve effluent treatment through oxidation, coagulation, and filtration processes. Two wastewater treatments were carried out. The first involved varying pH values and doses of H₂O₂ and FeCl₃, with a 24-hour sedimentation period followed by filtration. The treatment resulted in filtration, achieving 97% and 99% removal of COD and sulfides, respectively. The pH was not significant, but the H₂O₂ dose did influence the removal of sulfides and COD. In a second treatment, a combination of peroxone and H₂O₂/O₃ was applied, varying the sample concentration and H₂O₂ dosage while maintaining a constant pH of 8.5, flow rate, and O₃ concentration of 1000 mg/L. Oxidation was carried out for one hour, achieving COD removals of 81.7% and sulfide removals of 93.8%. Both treatments proved efficient for sulfide removal, but the peroxone treatment did not efficiently remove COD. It was concluded that both treatments remove sulfides below permissible levels, but the peroxone treatment uses less H₂O₂. The results obtained warrant further studies using oxygen for the simultaneous removal of sulfides and COD.

Keywords: chemical treatment, environmental, tanneries.

Mapping total mercury in rivers of Mato Grosso: baselines and contamination hotspots by biome

2025-12-03T22:14:48-03:00

Mercury (Hg) contamination is a critical environmental and public health concern due to its toxicity, persistence, and ability to biomagnify through aquatic food webs. This study mapped total mercury (HgT) concentrations in sediments from rivers across Mato Grosso, integrating geochemical parameters (HgT, organic matter, C/N ratio) and granulometric fractions. Statistical analyses included correlation, regression (OLS and GLM with Gamma distribution), and non-parametric comparisons (Kruskal-Wallis with post hoc tests). HgT concentrations ranged from 1.4 to 948.1 µg.kg⁻¹, with an overall mean of 109.1 ± 165.8 µg.kg⁻¹. Significant positive associations were observed between HgT and both organic matter (r = 0.50) and the C/N ratio (r = 0.70), with the latter emerging as the strongest predictor of Hg variability. Basin-level comparisons revealed that the Amazon had the highest mean concentrations (242.0 µg.kg⁻¹), followed by the Upper Paraguay (47.9 µg.kg⁻¹) and the Araguaia (29.3 µg.kg⁻¹). At the river scale, the Guaporé (731.5 µg.kg⁻¹) and Xingu (233.7 µg.kg⁻¹) were identified as contamination hotspots. Most rivers remained below the Threshold Effect Level (TEL = 170 µg.kg⁻¹) set by CONAMA Resolution 454/2012, but the Xingu exceeded the TEL and the Guaporé surpassed the Probable Effect Level (PEL = 486 µg.kg⁻¹), indicating high ecological risk. This study offers essential insights for environmental monitoring, water management, and biodiversity conservation, supporting Brazil’s commitments under the Minamata Convention.

Keywords: conservation, ecotoxicology, Hg, sediments.

The contribution of terracing for flood reduction in the urban area of Xanxerê (SC)

2025-12-03T22:32:22-03:00

The urban area of the town of Xanxerê, state of Santa Catarina, Brazil, faces inundation and flooding problems that demand complex structural measures due to intense urbanization over the natural drainage network. In addition, a large part of the farmland of the rural area presents soil erosion issues and water loss, which contributes to urban inundation. This study evaluated the contribution of the terracing technique in farming areas in reducing maximum runoff in the urban area of Xanxerê, Santa Catarina. Maximum runoffs were determined by the SCS hydrograph method for projected rain and return times of 25, 50 and 100 years. Scenarios such as the present situation were considered, as well as two others, with the implementation of drainage terracing and level terracing in farmlands with annual crops and pastureland. The effect of terracing was evaluated by CN alteration in these areas. For the rural basin, the implementation of gradient terracing reduces peak runoff by about 10%. The implementation of level terracing reduces peak runoff by around 50%. On the other hand, in the entire area of the basin under study, the use of gradient terracing reduced peak runoff by about 7%, while the use of level terracing reduced peak runoff by between 25 to 32%. Results demonstrate that adopting conservationist practices in rural areas can effectively contribute to solving urban drainage problems.

Keywords: erosion, soil conservation, terracing.