Identification of priority areas for water conservation in the Alto Iguaçu basin, Brazil.

Geoprocessing tools are great allies in the management of water resources, permitting the evaluation of several factors integrated into a multicriteria analysis. This improves the interpretation of the behavior of water and soil in hydrographic basins, allowing the delimitation of priority areas for actions. The objective of this study was to prepare a map of priority areas for water conservation in the Alto Iguaçu basin through a multicriteria analysis, aiming to assist in the management of water resources in the region. The priority map for water conservation was prepared using the weighted linear combination (WLC) method, considering the weight added to the factors that were obtained by the analytic hierarchy process (AHP) method. The method successfully identified priority areas for water conservation, where 40.7% of the Alto Iguaçu watershed was considered High priority and Very High priority, a number consistent with regional characteristics. The multicriteria analysis proved to be a flexible and easy to implement methodology, which can help managers when considering the trade-offs among several factors. The implementation of water conservation actions in areas that have been classified as being of High and Very High priority can benefit the regional ecosystem by controlling erosion, regulating the flow of water, and thus conserving the quantity and quality of water in the basin and its downstream region, benefiting the population and regional economics. Integr Environ Assess Manag 2023;00:1-12. © 2023 SETAC.

20-Month monitoring of SARS-CoV-2 in wastewater of Curitiba, in Southern Brazil.

The COVID-19 pandemic resulted in the collapse of healthcare systems and led to the development and application of several approaches of wastewater-based epidemiology to monitor infected populations. The main objective of this study was to carry out a SARS-CoV-2 wastewater based surveillance in Curitiba, Southern Brazil Sewage samples were collected weekly for 20 months at the entrance of five treatment plants representing the entire city and quantified by qPCR using the N1 marker. The viral loads were correlated with epidemiological data. The correlation by sampling points showed that the relationship between the viral loads and the number of reported cases was best described by a cross-correlation function, indicating a lag between 7 and 14 days amidst the variables, whereas the data for the entire city presented a higher correlation (0.84) with the number of positive tests at lag 0 (sampling day). The results also suggest that the Omicron VOC resulted in higher titers than the Delta VOC. Overall, our results showed that the approach used was robust as an early warning system, even with the use of different epidemiological indicators or changes in the virus variants in circulation. Therefore, it can contribute to public decision-makers and health interventions, especially in vulnerable and low-income regions with limited clinical testing capacity. Looking toward the future, this approach will contribute to a new look at environmental sanitation and should even induce an increase in sewage coverage rates in emerging countries.

Adaptive monitoring approach to assess dissolved organic matter dynamics during rainfall events.

Rainfall events induce water quality transformation in river systems influenced by the watershed land use and hydrology dynamics. In this context, an adaptive monitoring approach (AMA) is used to assess non-point sources (NPS) of pollution events, through dissolved organic matter (DOM) contribution. The case study is a monitoring site in a semi-urban watershed characterized by NPS contribution. An integrated quali-quantitative method for DOM based on dissolved organic carbon (DOC) content, spectroscopic techniques of excitation-emission fluorescence (EEF), and UV-visible absorbance is proposed. The results indicate a mix of allochthonous and autochthonous DOM characteristics from NPS sources associated to vegetation area influence (A285/DOC of 15.43 L (g cm)-1 and SUVA254 of 2.11 L (mg m)-1). The EEF signals showed more humic-like than protein-like characteristics with peaks A and C (approximately 5.72 r.u.) more intense than peaks B, T1, and T2 (approximately 4.33 r.u.), indicating NPS from the soil leachate. The absorbance ratio values indicate a mix of organic compounds with greater proportion of refractory characteristics with high aromaticity and molecular weight (approximately A300/A400 of 4.15 and A250/A365 of 4.48), associated with the surface wash-off of accumulated residual and subsurface soil erosion, which contribute to complex organic matter structures. The fluorescence indexes, overall, indicated allochthonous sources with intermediate humic characteristics (FI ≈ 1.43, BIX ≈ 0.65, and HIX ≈ 7.98). The proposed integrated optical property strategy represents an opportunity for better understanding of DOM dynamic assessment for identifying potential mitigation techniques for organic pollution control and improving water quality conditions.

Applicability of conventional and non-conventional parameters for municipal landfill leachate characterization.

The disposal of municipal solid waste (MSW) in landfills generates leachate, a highly polluting liquid to the aquatic environment. Leachate composition become a challenge to choose the best treatment process. Then, detailed techniques to determine the organic content, in terms of refractability, composition, sources and biodegradability in landfill leachate can help to choose the appropriate treatment and improve landfill management. In this sense, the aim of this study is to apply conventional and non-conventional parameters through inert chemical oxygen demand (COD) analyses and spectroscopic techniques of fluorescence and UV-vis absorbance for the characterization of municipal landfill leachate. Results indicated that physicochemical characterization cannot provided enough detailed information about leachate composition, which becomes the treatment process fragile. Inert COD, besides have high time to execution (∼30 days), presented additional information on potential of biological treatability in anaerobic conditions. Dissolved organic matter (DOM) characterization showed transitions between labile and refractory organic matter compounds. Moreover, the cost estimated showed that non-conventional parameters analysis have lower investment than conventional, being their implementation feasible. In conclusion, the synergy between conventional and non-conventional parameters, and the detailed information provided by inert COD and DOM characterization, shown a useful tool to the landfill management and, consequently, improving treatment process and its efficiency.

Water quality dynamic during rainfall episodes: integrated approach to assess diffuse pollution using automatic sampling.

Diffuse pollution caused by rainfall events potentially affects water quality in rivers and, therefore, must be investigated in order to improve water quality planning and management recovery strategies. For these, a quali-quantitative approach was used to monitor the water quality parameters in a river located in a semi-urban watershed area based upon automatic sampling. Thirteen water quality parameters were measured during five rainfall events. Events ranged from 2.3 to 56.8 mm and water peak flows from 3.3 to 4.5 m3/s. The pollutographs measured showed a standard pattern for total suspended solids (TSS). However, for the other chemical parameters, as total phosphorous (TP) and dissolved organic carbon (DOC), the dilution effects were more evident. It was possible to observe the rainfall influence mainly for physical parameters indicating a mass transport pattern for diffuse pollutants, which increased, for example, the amount of TSS in the river. Furthermore, hydrological characteristics were relevant considering the pollutant behavior. Antecedent dry periods, ranging from 1.3 days to 21.4 days, and critical time, from 2.0 to 10.4 h, are determinants to evaluate non-traditional water quality impacts in the river. In general, each rainfall episode has its own characteristics, which produces distinct mass contribution and temporal behavior, being challenging in making generalization. Therefore, the results indicate that diffuse pollution has to be considered to establish future decision-making strategies to water resources management.