RESUMO

Water pollution originating from land use and land cover (LULC) can disrupt river ecosystems, posing a threat to public health, safety, and socioeconomic sustainability. Although the interactions between terrestrial and aquatic systems have been investigated for decades, the scale at which land use practices, whether in the entire basin or separately in parts, significantly impact water quality still needs to be determined. In this research, we used multitemporal data (field measurements, Sentinel 2 images, and elevation data) to investigate how the LULC composition in the catchment area (CA) of each water pollution measurement station located in the river course of the Los Perros Basin affects water pollution indicators (WPIs). We examined whether the CAs form a sequential runoff aggregation system for certain pollutants from the highest to the lowest part of the basin. Our research applied statistical (correlation, time series analysis, and canonical correspondence analysis) and geo-visual analyses to identify relationships at the CA level between satellite-based LULC composition and WPI concentrations. We observed that pollutants such as nitrogen, phosphorus, coliforms, and water temperature form a sequential runoff aggregation system from the highest to the lowest part of the basin. We concluded that the observed decrease in natural cover and increase in built-up and agricultural cover in the upper CAs of the study basin between the study period (2016 to 2020) are related to elevated WPI values for suspended solids and coliforms, which exceeded the allowed limits on all CAs and measured dates.

Assuntos

RESUMO

Agriculture is an essential economic activity in Brazil. However, it is also the main source of water quality degradation. Monitoring catchments with agricultural land use is a way to generate information on a scale to identify causes and sources of water quality degradation. This work used monitoring data derived from hydrology and the quality of surface and underground water in an intensive agricultural catchment in the Atlantic Forest biome. The Fortaleza River catchment is located in the western part of Santa Catarina state in southern Brazil and has 62 km2 of drainage area. Hydrological and water quality monitoring was conducted for 7 years at two fluviometric stations, three lysimeters, one meteorological station, and one piezometer. Data on precipitation, temperature, water flow, surface runoff, drainage, and water quality were used. Statistical analyses were also developed. Precipitation between 2013 and 2019 presented a homogeneous distribution in monthly and annual data, with January and July the months with the highest and lowest values, respectively. Statistical difference in the average and Q95 flows was found in upstream and downstream fluviometric sections. In terms of quality, statistical differences were identified for ammonium, nitrate, and potassium concentrations, which had higher concentrations in lysimeter runoff, indicating direct influence of agricultural activity on water quality. Principal component analysis (PCA) indicated that (i) surface water presented a positive relationship in Component 1 for the magnesium-calcium, sulphate-chloride, and acetate-bromide groups and a negative relationship for phosphate-nitrate; (ii) in lysimeters, the positive relationship occurred for Component 2 for the phosphate-chloride and sulphate-nitrate groups and was negative for ammonium-lithium and calcium-potassium-magnesium; and (iii) in piezometer, positive relationships were found for chloride-sodium and phosphate-nitrite pairs, while negative relationships were found for calcium-magnesium.

Assuntos

RESUMO

Spatial-temporal monitoring of the presence of pesticides and pharmaceuticals in water requires rigor in the choice of matrix to be analyzed. The use of matrices, isolated or combined, may better represent the real state of contamination. In this sense, the present work contrasted the effectiveness of using epilithic biofilms with active water sampling and with a passive sampler-POCIS. A watershed representative of South American agriculture was monitored. Nine sites with different rural anthropic pressures (natural forest, intensive use of pesticides, and animal waste), and urban areas without sewage treatment, were monitored. Water and epilithic biofilms were collected during periods of intensive pesticide and animal waste application. After the harvest of the spring/summer crop, a period of low agrochemical input, the presence of pesticides and pharmaceuticals was monitored using the POCIS and epilithic biofilms. The spot water sampling leads to underestimation of the level of contamination of water resources as it does not allow discrimination of different anthropic pressures in rural areas. The use of endogenous epilithic biofilms as a matrix for the analysis of pesticides and pharmaceuticals is a viable and highly recommended alternative to diagnose the health of water sources, especially if associated with the use of POCIS.

Assuntos

RESUMO

The Espinal region (Entre Ríos, Argentina) has suffered land use changes caused by expansion of the agricultural frontier. This expansion has led to an increased use of pesticides. This study is aimed at better understanding the spatial distribution of pesticides in surface water of the Estacas stream, a representative basin of the Espinal region, associated with crop production. The location and proportion of area with soybean, maize, and wheat crops in each catchment area of the basin were estimated, and surface water samples were taken to perform a pesticide screening during a period of one year. Soybean represented approximately 71% of the total cultivated area of the basin, whereas maize and wheat accounted for 15% and 14%, respectively. The analysis of 125 analytes showed the presence of 19 pesticides. The pesticide load maps showed that atrazine was detected in an area of relatively low catchment compared to other pesticides as glyphosate, which is applied in all the agricultural fields of the basin. The load of metolachlor and S-metolachlor covered a large area of the basin. The highest recorded concentrations of these pesticides were 86 µg L-1 of atrazine, 24 µg L-1 of metolachlor, 19 µg L-1 of glyphosate, and 15 µg L-1 of S-metolachlor. The results allow better understanding the environmental distribution of pesticides associated with pest control in the crops of the basin studied, the doses and times of application, and the variation in the rainfall in the basin. This study provides relevant information about how aquatic ecosystems in agricultural basins receive the diffuse contribution of pesticides, representing potential sources of water pollution. Also, the results allow supporting the design of agricultural practices and politics to improve land-use planning for the development of sustainable basins.

Assuntos

RESUMO

Glyphosate-based herbicides can be harmful to the environment and human health. Especially in developing countries, these herbicides are often used indiscriminately in agricultural and urban areas. Here, we optimized a simple and efficient flow injection-based spectrophotometric method to monitor environmentally relevant glyphosate concentrations in surface waters. The method was then used to assess the environmental mobility of glyphosate in Southeast Brazil by monitoring surface runoff from experimental agricultural soil plots that received glyphosate applications in 2015. Further, water samples from low-order streams were collected in five agricultural, urban, and natural areas, as well as from the 5th-order Rio das Mortes during the rainy season. Finally, 20 drinking water sources were sampled in urban, rural, and agricultural areas. Runoff from reference plots without glyphosate application showed concentrations below the method's detection limit of 0.49 mg.L-1, whereas runoff from plots with standard glyphosate application had concentrations between 1.24 and 6.1 mg.L-1. Similarly, concentrations in natural stream water were below the detection limit, whereas agricultural streams had concentrations of up to 3.7 mg.L-1 (average: 0.97 mg.L-1). In an agricultural stream monitored weekly, concentration peaks were observed after glyphosate applications by farmers, and concentrations were correlated to stream discharge. Urban streams had concentrations of up to 5.8 mg.L-1 (average: 2.6 mg.L-1), but samples from the catchment's major river were mostly below detection limits, illustrating the dilution of urban and agricultural runoff in high-order rivers. In the sampled drinking water resources, glyphosate pollution occurred mainly in the rainy season, with detectable concentrations between 0.5 and 8.7 mg.L-1 in 80% of the sampled drinking water sources. In conclusion, our results suggest considerable environmental mobility of glyphosate in the studied Southeast Brazilian catchment. Substantial pollution, well above national and international limits, was detected in surface runoff, stream water, and drinking water resources.

Assuntos

RESUMO

Most residences in the United States Virgin Islands (USVI) rely on household rainwater-catchment systems and subterranean cisterns for long-term water storage that may provide suitable habitats for mosquitoes of public health relevance. We conducted a household cistern survey (n = 164) on the islands of St. Croix, St. John, and St. Thomas in 2019. The survey revealed that 45.7% (95% CI: 38.3-53.4%) of cisterns contained mosquitoes (adult and/or immature mosquitoes). Aedes aegypti, a vector of chikungunya, dengue, and Zika viruses in the USVI, was found in 27.4% (95% CI: 21.2-34.7%) of cisterns and accounted for 83.3% of the total mosquitoes identified in the study. The odds of detecting mosquitoes in a cistern were 5.45 times higher at locations where the residents reported that they had observed adult mosquitoes coming out of their cisterns (95% CI: 2.25-14.21), suggesting that vector control personnel should consider resident complaints about mosquitoes in their cistern as valid and likely reliable self-assessments. Resident mosquito management practices in cisterns did not correspond with decreased odds of mosquito detection. We conclude that cisterns in the USVI commonly provide habitat for immature and adult Ae. aegypti, which may decrease the effectiveness of area-wide mosquito control strategies. Additional studies are necessary to evaluate the importance of these cisterns as they relate to mosquito production and arbovirus transmission risk, and to assess physical and chemical control methods.

Assuntos

RESUMO

BACKGROUND: Higher-than-expected heart failure (HF) readmissions affect half of US hospitals every year. The Hospital Reduction Readmission Program has reduced risk-adjusted readmissions, but it has also produced unintended consequences. Shared care models have been advocated for HF care, but the association of shared care networks with HF readmissions has never been investigated. OBJECTIVE: This study aims to evaluate the association of shared care networks with 30-day HF excessive readmission rates using a longitudinal observational study. METHODS: We curated publicly available data on hospital discharges and HF excessive readmission ratios from hospitals in California between 2012 and 2017. Shared care areas were delineated as data-driven units of care coordination emerging from discharge networks. The localization index, the proportion of patients who reside in the same shared care area in which they are admitted, was calculated by year. Generalized estimating equations were used to evaluate the association between the localization index and the excessive readmission ratio of hospitals controlling for race/ethnicity and socioeconomic factors. RESULTS: A total of 300 hospitals in California in a 6-year period were included. The HF excessive readmission ratio was negatively associated with the adjusted localization index (ß=-.0474, 95% CI -0.082 to -0.013). The percentage of Black residents within the shared care areas was the only statistically significant covariate (ß=.4128, 95% CI 0.302 to 0.524). CONCLUSIONS: Higher-than-expected HF readmissions were associated with shared care networks. Control mechanisms such as the Hospital Reduction Readmission Program may need to characterize and reward shared care to guide hospitals toward a more organized HF care system.

RESUMO

RESUMEN Fundamento: la pesquisa activa en los alumnos de las Ciencias Médicas constituye unas de las fortalezas de la Educación Médica Superior en Cuba implementadas desde la Atención Primaria de Salud para la identificación de los factores de riesgo y lograr salud en la comunidad. Objetivo: caracterizar la pesquisa activa de los alumnos de las Ciencias Médicas en prevención del COVID-19 en un área de salud. Métodos: se realizó un estudio descriptivo trasversal en el área de salud del Policlínico Docente Francisco Peña Peña del municipio de Nuevitas en la provincia Camagüey desde abril a mayo de 2020. El universo se conformó por los 142 estudiantes de Medicina, Estomatología, Enfermería y Tecnologías de la Salud a participar en la pesquisa activa. Resultados: se determinó la carrera de Medicina como la más representativa en la participación de los alumnos en la pesquisa, se identificaron por los estudiantes 115 personas con sintomatología respiratoria, de ellos existió un discreto predominio del sexo femenino y predominó el grupo de edad de 41-60 años, el mayor porcentaje de la población mostró un nivel de muy satisfecho con la labor realizada por los galenos universitarios. Conclusiones: los estudiantes de la carrera de Medicina fueron los de mayor participación en las labores de pesquisa activa, el tema de vías de transmisión para el control del virus fue de los que más conocimiento tenían los galenos, identificaron síntomas respiratorios en las féminas, entre la cuarta y sexta década de vida, casi la totalidad de la población pesquisada manifestó un nivel muy satisfecho en relación al desempeño de los estudiantes durante las labores preventivas de pesquisa activa.

ABSTRACT Background: active research in students of Medical Sciences constitutes one of the strengths of Medical Higher Education in Cuba implemented from Primary Health Care to identify risk factors and achieve health in the community. Objective: to characterize the active research of students of Medical Sciences in COVID-19 prevention in a health area. Methods: a cross-sectional descriptive study was carried out in the health area of ​​the Francisco Peña Peña Teaching Polyclinic of Nuevitas in the period from April to May 2020. The universe was formed by the 142 students of medicine, dentistry, nursing and technological careers to participate in active research. Results: the most representative medical degree in the participation of Medical Sciences students in the research was determined, 115 people with respiratory symptoms were identified by the students, of them there was a discrete predominance of the female sex and the group of the age of 41-60 years, the highest percentage of the population showed a level of very satisfied with the work carried out by students of the University of Medical Science. Conclusions: the medical career was the one with the highest participation in active research tasks, the issue of transmission routes for virus control was one of which the doctors knew the most, respiratory symptoms were identified in females, among the fourth and the sixth decade of life, almost the entire population surveyed showed a very satisfied level in relation to the performance of the students during the preventive work of active research.

RESUMO

RESUMO O Plano de Segurança da Água (PSA) contempla, entre outras etapas, a identificação e o acompanhamento de eventos perigosos e pode garantir qualidade hídrica aos consumidores. A ruralidade abrange cerca de 15% da população brasileira e o acompanhamento técnico é insuficiente para atender às demandas locais. Nesse contexto, o principal objetivo foi elaborar um modelo conceitual de PSA para monitoramento de riscos à contaminação da água na área rural, contemplando eventos desde a captação até a distribuição de água em comunidades rurais. A metodologia consistiu em caracterização de eventos perigosos, concepção do modelo computacional, consulta a especialistas e calibração e aplicação do modelo em propriedades rurais. Entre os resultados, tem-se um software elaborado em Python contendo 109 eventos direcionados ao abastecimento rural. O programa analisou a precariedade no entorno da captação de água e as condições de limpeza das propriedades estudadas. Os resultados indicaram que os riscos mais elevados, em sua maioria, são provenientes do uso de fossa negra, descarte irregular de resíduos sólidos, lançamento de esgoto doméstico a céu aberto e criação de animais nas proximidades da captação de água. Não há softwares disponíveis para mensuração de riscos ao abastecimento de água em áreas rurais e o modelo proposto pode ser utilizado para avaliação da salubridade rural no contexto nacional. Dessa forma, o software subsidia o monitoramento dos recursos hídricos e amplia a capacidade de gerenciamento no setor.

ABSTRACT The Water Safety Plan (WSP) includes, among other steps, the identification and monitoring of dangerous events can guarantee water quality to consumers. Rurality covers about 15% of the Brazilian population and technical support is insufficient to assist local demands. In this context, the main objective was to develop a conceptual WSP model for monitoring water contamination risks in the rural area, contemplating events from water catchment to water distribution in rural communities. The methodology consisted of the characterization of dangerous events, conception of the computational model, specialists consultation, and model calibration and application in rural properties. Among the results, there is a software elaborated in Python containing 109 events aimed at rural supply. The program analyzed the precariousness around the water catchment and the clean conditions of the studied properties. These results indicated the highest risks, for the most part, come from the use of cesspool, irregular disposal of solid waste, domestic sewage discharge, and animal beeding nearby water catchment. There is no software available to measure water supply risks in rural areas and the proposed model can be used for environmental health evaluatiation in the national context. In this way, the software can support water resource monitoring and expands the manageability in the sector.

RESUMO

The rapid spread of COVID-19 across the world has raised concerns about the responsiveness of cities and healthcare systems during pandemics. Recent studies try to model how the number of COVID-19 infections will likely grow and impact the demand for hospitalization services at national and regional levels. However, less attention has been paid to the geographic access to COVID-19 healthcare services and to hospitals' response capacity at the local level, particularly in urban areas in the Global South. This paper shows how transport accessibility analysis can provide actionable information to help improve healthcare coverage and responsiveness. It analyzes accessibility to COVID-19 healthcare at high spatial resolution in the 20 largest cities of Brazil. Using network-distance metrics, we estimate the vulnerable population living in areas with poor access to healthcare facilities that could either screen or hospitalize COVID-19 patients. We then use a new balanced floating catchment area (BFCA) indicator to estimate spatial, income, and racial inequalities in access to hospitals with intensive care unit (ICU) beds and mechanical ventilators while taking into account congestion effects. Based on this analysis, we identify substantial social and spatial inequalities in access to health services during the pandemic. The availability of ICU equipment varies considerably between cities, and it is substantially lower among black and poor communities. The study maps territorial inequalities in healthcare access and reflects on different policy lessons that can be learned for other countries based on the Brazilian case.

Assuntos

RESUMO

We employ the approach of Roderick and Farquhar (2011) to assess the sensitivity of runoff (R) given changes in precipitation (P), potential evapotranspiration (Ep ), and other properties that change the partitioning of P (n) by estimating coefficients that predict the weight of each variable in the relative change of R. We use this framework using different data sources and products for P, actual evapotranspiration (E), and Ep within the Amazon River basin to quantify the uncertainty of the hydrologic response at the subcatchment scale. We show that when estimating results from the different combinations of datasets for the entire river basin (at Óbidos), a 10% increase in P would increase R on average 16%, while a 10% increase in Ep would decrease R about 6%. In addition, a 10% change in the parameter n would affect the hydrological response of the entire basin around 5%. However, results change from catchment to catchment and are dependent on the combination of datasets. Finally, results suggest that enhanced estimates of E and Ep are needed to improve our understanding of the future scenarios of hydrological sensitivity with implications for the quantification of climate change impacts at the regional (subcatchment and subbasin) scale in Amazonia.

Assuntos

RESUMO

The paper presents an analysis of runoff behaviour of four urban catchments between the municipalities of Belo Horizonte and Contagem in Brazil, linked to their land use. Two years of online measurement of flow data, combined with spatial analysis, was linked through runoff modelisation with EPA SWMM. The coefficients of Nash obtained varying between 0.75 and 0.87 demonstrated an adequate modelling approach. A 1-year rain series was applied to evaluate the runoff behaviour of actual land cover and that of 2002. The peak flows normalised to watershed surfaces revealed as the most urbanised (85%) watershed Ressaca with 178 L/ha/s, three times more runoff intensive than the least urbanised (41%) Mergulhão with 67 L/ha/s. Statistical analysis of land cover data and modelling results on watershed and sub-watershed level showed main correlations between hydrological parameters such as peak flow, average event flow and restitution time, but also between land cover and runoff coefficient. This approach gave a linear relation between runoff and green surface, with a runoff coefficient of 0.86 for fully urbanised zone and 0.43 for full "green" cover. Prospective simulation with actual urbanisation rates varying from 4 to 34 ha/year suggested an increase between 6 and 18% of the flows and a possible end of urbanisation within the next two to three decades. These findings should contribute to a better understanding of hydrological impact of Belo Horizonte urbanisation and to the restauration of its Lake Pampulha.

Assuntos

RESUMO

BACKGROUND: The geographical accessibility of health services is an important issue especially in developing countries and even more for those sharing a border as for Haiti and the Dominican Republic. During the last 2 decades, numerous studies have explored the potential spatial access to health services within a whole country or metropolitan area. However, the impacts of the border on the access to health resources between two countries have been less explored. The aim of this paper is to measure the impact of the border on the accessibility to health services for Haitian people living close to the Haitian-Dominican border. METHODS: To do this, the widely employed enhanced two-step floating catchment area (E2SFCA) method is applied. Four scenarios simulate different levels of openness of the border. Statistical analysis are conducted to assess the differences and variation in the E2SFCA results. A linear regression model is also used to predict the accessibility to health care services according to the mentioned scenarios. RESULTS: The results show that the health professional-to-population accessibility ratio is higher for the Haitian side when the border is open than when it is closed, suggesting an important border impact on Haitians' access to health care resources. On the other hand, when the border is closed, the potential accessibility for health services is higher for the Dominicans. CONCLUSION: The openness of the border has a great impact on the spatial accessibility to health care for the population living next to the border and those living nearby a road network in good conditions. Those findings therefore point to the need for effective and efficient trans-border cooperation between health authorities and health facilities. Future research is necessary to explore the determinants of cross-border health care and offers an insight on the spatial revealed access which could lead to a better understanding of the patients' behavior.

Assuntos

RESUMO

Lake Nahuel Huapi (NH) is a large, ultraoligotrophic deep system located in Nahuel Huapi National Park (NHNP) and collecting a major headwater network of Northwestern Patagonia (Argentina). Brazo Rincón (BR), the westernmost branch of NH, is close to the active volcanic formation Puyehue-Cordón Caulle. In BR, aquatic biota and sediments display high levels of total Hg (THg), ranging in contamination levels although it is an unpolluted region. In this survey, Hg species and fractionation were assessed in association with dissolved organic matter (DOM) in several aquatic systems draining to BR. THg varied between 16.8 and 363 ng L-1, with inorganic Hg (Hg2+) contributing up to 99.8% and methyl mercury (MeHg) up to 2.10%. DOC levels were low (0.31-1.02 mg L-1) resulting in high THg:DOC and reflecting in high Hg2+ availability for binding particles (partitioning coefficient log Kd up to 6.03). In streams, Hg fractionation and speciation related directly with DOM terrestrial prints, indicating coupled Hg-DOM inputs from the catchment. In the lake, DOM quality and photochemical and biological processing drive Hg fractionation, speciation and vertical levels. Dissolved gaseous Hg (Hg0) reached higher values in BR (up to 3.8%), particularly in upper lake layers where solar radiation enhances the photoreduction of Hg2+ and Hg-DOM complexes. The environmental conditions in BR catchment promote Hg2+ binding to abiotic particles and bioaccumulation and the production of Hg0, features enhancing Hg mobilization among ecosystem compartments. Overall, the aquatic network studied can be considered a "natural Hg hotspot" within NHNP.

Assuntos

RESUMO

RESUMO Este trabalho teve como objetivo avaliar a primeira carga de lavagem de uma bacia urbana da cidade de Natal, Rio Grande do Norte, por meio da quantificação de cargas poluentes contidas nos deflúvios superficiais em decorrência de nove eventos de precipitação pluviométrica, monitorados ao longo do ano de 2013. As variáveis analisadas foram: sólidos totais, sólidos suspensos totais, demanda química de oxigênio, fósforo total e teor de óleos e graxas. Foi realizada a avaliação dos eventos de precipitação/escoamento, mediante amostragem progressiva do runoff, monitorado por meio de amostrador automático (ISCO 6712), situado no exutório da bacia, sendo analisados os primeiros 24 minutos do escoamento superficial, com amostras coletadas a cada minuto ao longo do evento. A variação da concentração dos poluentes associada à variação temporal dos deflúvios durante eventos de precipitação foi analisada para a verificação da ocorrência do fenômeno first flush ou primeira carga de lavagem. O período monitorado caracterizou-se por apresentar baixo intervalo de dias de estiagem entre os eventos. Foi observada a ocorrência de primeira carga de lavagem em cinco dos eventos monitorados. Dessa forma, evidenciou-se que para a bacia estudada o conceito de first flush pode ser aplicado nas estratégias de manejo de águas pluviais, para implementação de boas práticas de manejo, que vêm sendo amplamente difundidas no que concerne à drenagem urbana.

ABSTRACT The aim of this study was to evaluate the first wash load of an urban catchment located in the city of Natal, Rio Grande do Norte, Brazil, by quantifying pollution loads contained in surface run-offs from nine rainfall events, monitored throughout the year 2013. The variables analyzed were: total solids, total suspended solids, chemical oxygen demand, total phosphorus and oil and grease content. We conducted the evaluation of precipitation/runoff events through progressive sampling of runoff, monitored by autosampler (ISCO 6712), and located at the outlet of the drainage basin. The first 24 minutes of runoff were analyzed, with samples collected every minute throughout the event. The variation of the pollutants concentration associated with the temporal run-offs variation during precipitation was analyzed to verify the occurrence of the first flush phenomenon. The monitored period was characterized by having a low number of drought days between events. The occurrence of the first flush was observed in five of the monitored events. Thus, it became clear that for the studied basin, the concept of first flush could be applied in rainwater management strategies for the implementation of best management practices, which have been widely disseminated regarding urban drainage.

RESUMO

The understanding of factors affecting pesticide transfers to catchment outlet is still at a very early stage in tropical context, and especially on tropical volcanic context. We performed on-farm pesticide use surveys during 87 weeks and monitored pesticides in water weekly during 67 weeks at the outlet of a small catchment in Martinique. We identified three types of pollution. First, we showed long-term chronic pollution by chlordecone, diuron and metolachlor resulting from horticultural practices applied 5-20 years ago (quantification frequency higher than 80%). Second, we showed peak pollution. High amounts of propiconazole and fosthiazate applied at low frequencies caused river pollution peaks for weeks following a single application. Low amounts of diquat and diazinon applied at low frequencies also caused pollution peaks. The high amounts of glyphosate applied at high frequency resulted into pollution peaks by glyphosate and aminomethylphosphonic acid (AMPA) in 6 and 20% of the weeks. Any intensification of their uses will result in higher pollution levels. Third, relatively low amounts of glufosinate-ammonium, difenoconazol, spinosad and metaldehyde were applied at high frequencies. Unexpectedly, such pesticides remained barely detected (<1.5%) or undetected in water samples. We showed that AMPA, fosthiazate and propiconazole have serious leaching potential. They might result in future chronic pollution of shallow aquifers alimenting surface water. We prove that to avoid the past errors and decrease the risk of long-term pollution of water resources, it is urgent to reduce or stop the use of pesticides with leaching potential by changing agricultural practices.

Assuntos

RESUMO

Thermotolerant coliform (TC) loadings were quantified for 49 catchments draining into the North and South Bays of Santa Catarina (SC, southeastern Brazil), an area known for its tourism and aquaculture. TC loadings were calculated based on flow measurements taken in 26 rivers. TC concentrations ere quantified based on surface water samples collected at 49 catchment outlets in 2012 and 2013. Median TC loads ranged from 3.7 × 103 to 6.8 × 108 MPN s-1. TC loadings in the catchments increased in proportion to increases in resident human population, population density and percentage of urbanised area. Catchments with more than 60% of area covered by wastewater collection and treatment systems had higher TC loads per person than catchments with less than 25%. Based on the study catchments, these results indicate that current sewerage infrastructure is ineffective in reducing contamination of faecal origin to surface waters. These findings have important implications for the management of microbiological health hazards in bathing, recreational and shellfish aquaculture waters in the North and South Bays of Santa Catarina Island.

Assuntos

RESUMO

For countries dependent on hydroelectricity, water scarcity poses a real risk. Hydroelectric plants are among the most vulnerable enterprises to climate change. Investing in the conservation of the hydrographic basin is a solution found by the hydropower sector. Given the importance of the Itaipu plant to the energy matrix of Brazil and Paraguay, the aim of this study is to review the current distribution of royalties from Itaipu, using the hydrographic basin as a of criterion of analysis. Approximately 98.73% of the Itaipu basin is in Brazil. The flow contributes 99% of the total electricity generated there, while the drop height of the water contributes only 1%. Under the current policy, royalties are shared equally between Brazil and Paraguay. In the proposed approach, each country would receive a percentage for their participation in the drop height and water flow in the output of the turbines, which are intrinsic factors for electricity generation. Thus, Brazil would receive 98.35% of the royalties and Paraguay, 1.65%. The inclusion of the hydrographic basin as a criterion for the distribution of royalties will promote more efficient water resource management, since the payment will be distributed throughout the basin of the plant. The methodology can be applied to hydroelectric projects worldwide.

Assuntos

RESUMO

Phosphate sorption-desorption parameters like maximum phosphorus (P) adsorption capacity (P max), equilibrium phosphorus concentration (EPC), water desorbable P (α), potentially bioavailable P (ß), and mobility index (α/ß ratio) were determined in order to understand the sediment source-sink nature in Guaporé catchment in southern Brazil during summer and winter 2013 and 2014. The result showed a significant (p = 0.05) variation across sediment site or seasons and revealed the most sorption-desorption parameters (P max, α, ß) with the increments following the order urban sediments > intensive agriculture under CT > intensive agriculture under NT > low agriculture sub-catchments (sub1 and sub2) > native forest. In the main river points, these parameters decreased along the river (P1 to P5). The results were more obvious in winter than the summer season. In contrast, the low values of λ and α/ß ratio in the sediment from native forest and relatively less polluted catchment (sub1) during summer season show the quick P desorption when compared to specific Fe and Al oxides bound to stable P in intensive agriculture sediments. These findings clearly indicated that agricultural practices, sediment characteristics, and hydrological factors have a major impact on seasonal sediment P bioavailability and mobility. The urban untreated discharges may be a single major P source and, if it is not wisely managed, proves a major threat to water quality. These results have serious implications for the river ecosystem and will be of great importance to improve the environmental and economic performance of agricultural practices aiming to reduce soil-based P legacy to surface waters.

Assuntos

RESUMO

Fluvial networks transport a substantial fraction of the terrestrial production, contributing to the global carbon cycle and being shaped by hydrologic, natural and anthropogenic factors. In this investigation, four Andean Patagonian oligotrophic streams connecting a forested catchment (~125km(2)) and draining to a double-basin large and deep lake (Lake Moreno complex, Northwestern Patagonia), were surveyed to analyze the dynamics of the allochthonous subsidy. The results of a 30month survey showed that the catchment supplies nutrients and dissolved organic matter (DOM) to the streams. The eruption of the Puyehue-Cordón Caulle at the beginning of the study overlapped with seasonal precipitation events. The largest terrestrial input was timed with precipitation which increased particulate materials, nutrients and DOM through enhanced runoff. Baseline suspended solids and nutrients were very low in all the streams (suspended solids: ~1mg/L; total nitrogen: ~0.02mg/L; total phosphorus: ~5µg/L), increasing several fold with runoff. Baseline dissolved organic carbon concentrations (DOC) ranged between 0.15 and 1mg/L peaking up to three-fold. Chromophoric and fluorescent analyses characterized the DOM as of large molecular weight and high aromaticity. Parallel factor modeling (PARAFAC) of DOM fluorescence matrices revealed three components of terrestrial origin, with certain degree of microbial processing: C1 and C2 (terrestrial humic-like compounds) and C3 (protein-like and pigment derived compounds). Seasonal changes in MOD quality represent different breakdown stages of the allochthonous DOM. Our survey allowed us to record and discuss the effects of the Puyehue-Cordón Caulle eruption, showing that due to the high slopes, high current and discharge of the streams the volcanic material was rapidly exported to the Moreno Lake complex. Overall, this survey underscores the magnitude and timing of the allochthonous input revealing the terrestrial subsidy to food webs in Patagonian freshwaters, which are among the most oligotrophic systems of the world.

Assuntos