Seaweed-based biostimulants (SBB) have emerged as sustainable alternatives for traditional soil-based agriculture and have garnered worldwide attention in recent years. Despite their growing popularity, there is limited information available on the application and efficacy of SBB in hydroponic crops. This study assesses the biostimulant effects of a commercial SBB using Lemna minor as a model organism, developing a standardized bioassay for evaluating SBB in hydroponic cultures. The experiment was carried out under controlled conditions, following a randomized design with 10 treatments. These treatments included SBB (0T1, 0.5T1, 2T1) alone at concentrations of 0, 0.5, and 2.0 mg/L, SBB (0T2, 0.5T2, 2T2) + Hoagland and Arnon nutrient solution, and SBB (0T30, 0.5T3, 2T3) + 2.5 g/L NaCl. A control group (0TC) with distilled water was also included. The results showed that the isolated SBB did not significantly differ (p > 0.05) from the control treatment. Treatments in group T2 had significantly higher coverage area compared to treatments in group T3. The highest absolute percentage of coverage area was observed in 0.5T2 (14.0 ± 1.2%). Regarding the specific growth rate SGR, the higher growth rates were observed in 0.5T2 (0.37 ± 0.02% day⁻1). Group T2 treatments exhibited significantly higher dry biomass (p < 0.05) than group T3 treatments. Treatment with NaCl hindered plant growth. This methodology could enhance the development of a robust protocol for evaluating seaweed biostimulants for hydroponic crops. Keywords: biostimulants, duckweed, seaweed extract.

The sugar-energy industry generates large volumes of waste, among which vinasse stands out for its potential in agricultural use. However, its use in fertigation requires careful management to prevent soil salinization and soil quality degradation. This study evaluated whether sorption treatment of vinasse with sugarcane bagasse ash (SBA) can simultaneously neutralize its acidity and improve its nutrient composition, thereby mitigating its adverse effects on soil. To this end, 100 mL of raw vinasse was treated with 5.0 g of SBA through three consecutive 24-h sorption cycles. Treated vinasse was applied to PVC columns filled with sandy and clay soils, and was compared with untreated vinasse. Soil physicochemical properties, including electrical conductivity, volumetric moisture, nutrient composition, and sodicity indices, were evaluated. Results indicated that 5.0 g of SBA with a 72-h contact time optimized sorption, increasing the vinasse pH and nutrient availability. Treated vinasse enhanced chemical stability in clay soils, whereas sandy soils showed higher leaching susceptibility. In both soil types, the exchangeable sodium percentage (ESP) remained below 15%, indicating no risk of soil sodification. The results suggest that sorption-treated vinasse is a sustainable fertigation alternative, particularly for clay soils, while sandy soils require stricter application management to prevent nutrient leaching. Keywords: adsorption, agricultural sustainability, soil fertility, waste.

This study evaluated mineral nitrogen (NH₄⁺ and NO₃⁻) concentrations and potential mineralization and nitrification rates in soils under No-Tillage (NT) and Conventional Tillage (CT) in soybean fields in the Santarém Plateau, Pará, Brazil. Soil samples were collected at three phenological stages (R1: flowering; R5: grain filling; R8: physiological maturity) and four depths (0 – 10, 10 – 20, 20 – 30, 30 – 40 cm). No significant differences were observed between NT and CT for mineral N concentrations or transformation rates, suggesting that after two years of NT adoption, short-term effects on N dynamics are minimal. Mineral N concentrations decreased significantly (p< 0.05) from R1 to R8, mainly in deeper layers (10 – 40 cm), likely due to intense N uptake by soybean during early reproductive stages. The highest daily mineralization and nitrification rates occurred in the 0 – 10 cm layer, associated with greater organic matter and microbial activity. Positive transformation rates at all depths indicate continuous conversion of organic N into plant-available forms throughout the crop cycle. Results suggest that NT benefits on soil N cycling in Amazonian agricultural systems may become more evident over longer adoption periods, particularly when integrated with crop rotation and permanent soil cover. Keywords: agricultural management systems, ammonium and nitrate, nitrogen transformation rates, soil nitrogen cycling, tropical agriculture.

This study presents the results of field surveys regarding flow measurements, water collection and suspended sediment samples, laboratory analyses (grain-size distribution, suspended sediment concentration, and total dissolved solids), and calculations of suspended sediment load in the watershed of the Paiva Castro Reservoir, Mairiporã, SP. The activities were conducted from October 2023 to December 2024, comprising 21 monitoring campaigns. Five sediment monitoring stations were defined along the Juqueri River. Measurements involved flow gauging using an acoustic Doppler device (ADCP RS-5) and collection of suspended sediments using a DH-48 sampler, in addition to laboratory analyses of suspended sediment concentration, particle size, and total dissolved solids. The equal-width increment (EWI) method was used, allowing detailed vertical and cross-sectional sediment distribution data. The results highlight the spatial and temporal variability of suspended sediment concentrations, which is essential for understanding erosion processes and for planning preventive and corrective actions to mitigate reservoir siltation. Keywords: hydrosedimentology, solid discharge, total dissolved solids.

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.

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.

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.

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.

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.

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.