The use of environmental tracers brings comprehensive benefits to the management of water resources since it helps to prevent their pollution, minimize public health risks, and thus reduce the impact ...of urbanization. In Brazil, the Guarani Aquifer System (GAS) has strategic and environmental importance, making its preservation and sustainable exploitation mandatory. The present study aimed at evaluating sources of contamination in the GAS using the combination of geochemical data and two environmental tracers: nitrate isotopes (
15
N
NO3
and
18
O
NO3
) and one rare earth element (Gadolinium—Gd). For that, five wells—four exploiting the GAS and one the Bauru Aquifer System (BAS)—were selected to discuss the human inputs in groundwater used for public supply in an urban area. Traditional physicochemical analyses were conducted for six campaign samplings and nitrate monitoring for this period was evaluated on a time scale, also considering the accumulated rainfall. Besides that, the double isotopic method (DIM), e.g., δ
18
O
NO3
e δ
15
N
NO3
, was applied to identify the fractionation and enable the distinction of the nitrate contamination source. In addition, the determination of anomalies of Gd, a wastewater-derived contaminant, was also performed to verify recent human inputs in groundwater. The results show that the local existence of nitrate in the GAS and BAS—even at low concentrations (values from 0.26 to 6.68 mg L
−1
)—originated from anthropogenic inputs (septic waste), as indicates the typical isotopic signals ratio in the isotopic approach. Associated with that, the evaluation of Gd permitted the separation of groundwater samples into older or more recent leakages. The use of environmental tracers to assess anthropogenic inputs in groundwater reiterates the importance of adopting more effective protection strategies for water resources management systems, in order to prevent contamination.
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•Inadequate waste disposal areas (n = 104) in Brazil were assessed for contamination.•Most studies were published in Portuguese, undermining dissemination.•Contamination of ...groundwater and surface water was observed in most studies (>70%)•Coliforms, biochemical oxygen demand, and lead were frequently above Brazilian legislation.•Most dumpsites have insignificant or low vulnerability to groundwater contamination.
This work presents an overview of environmental studies performed in areas affected by dumpsites and non-sanitary landfills in Brazil, focusing on physicochemical analysis of surface water, groundwater, and soils, as well as geophysical surveys. The objective was to identify the main contaminants found in these areas and to assess their environmental impact, guiding possible intervention measures, indicating the priority areas, and showing whether post-closure activities are mandatory. The results should support governmental actions, especially considering the recent approval of Brazil’s new sanitation framework. The present review assessed 162 publications, which described 104 different municipal solid waste (MSW) disposal sites. The physicochemical parameters of analyzed surface water, groundwater, and soil samples were above Brazilian legislation levels in 74%, 70%, and 24% of the studies, respectively. The parameters more frequently above permissible levels were coliforms, biochemical oxygen demand, dissolved oxygen, and phosphorus for surface water; lead, coliforms, and iron for groundwater; copper, cadmium, lead, and zinc for soil. The results indicated that Brazilian dumpsites are causing negative impacts in surrounding soils and water resources, posing ecological and public health risks that persist even after the site’s closure. Considering that this study provides only a reduced scenario, the dimension of this environmental problem in Brazil is noteworthy. Therefore, it is suggested that not only inadequate disposal is prohibited, but also efficient enforcement methods are adopted and aftercare is appropriately regulated in the country, making it obligatory to establish monitoring plans and implement mitigation techniques to avoid abandoning potentially contaminated areas.
Engineered capping systems are efficient tools for the safety concept for landfills and contaminated land, consisting of multilayer barriers installed at the top of the deposited waste, even years ...after its closure. The efficiency of such systems is closely associated with avoiding rainwater infiltration into the waste body, a process that can be assessed and monitored with geophysical methods, such as Electrical Resistivity Tomography (ERT). A surface geomembrane capping of approximately 900 m
2
was installed over an abandoned unlined landfill in southeastern Brazil and ERT surveys were adopted to assay the effectiveness of the intervention measure. It was possible to verify significantly more resistive regions below the geomembrane and an increase in conductivity values only at approximately 6 m, at the groundwater level of the area. Thus, the reduction of rainwater input possibly, even in the short term, reduces the moisture content and prevents the formation of leachate sheets in unlined landfills, leading the deposit to be more isolated from the surroundings. Lateral flow affected distances as far as 2.5 m from the capping borders, showing that about 70% of the capped area was effectively isolated from the rainfall infiltration. Therefore, capping contributed to reducing leachate production and can be considered an effective method for mitigating impacts from old unlined landfills.
hydrological monitoring is essential for a proper decision-making process and modelling. Efforts have been made in Brazil to carry out field activities at the basin scale, but how complete and ...comprehensive are those studies? Where are they located? How long have they been carried out? What are the main findings? To answer these questions, an overview of experimental monitoring basins in Brazil is presented, listing their geographical locations, monitored variables, operational status, monitoring periods and main publications. We identified 60 monitored sites, spread across most Brazilian biomes, with an average monitoring period of 12 years. However, some publications from these monitoring studies are not fully accessible to the international community. Field hydrology activities in Brazil contribute to a better understanding of hydrological processes in humid and semi-arid regions and inform us about the impacts of land-use change on water quality and quantity.
Abstract
Flexible fiber filters are recently developed modular filtration units which have been applied to wastewater and water treatments, satisfactorily removing solids even when operated at high ...application rates. In this paper, polypropylene fibers, in lieu of the commonly used polyamide fibers, were tested for constructing filtration modules containing parallel fibers. The studied fibers were analyzed by means of scanning electronic microscopy and through solubility assays in hydrochloric acid and sodium hydroxide, aiming to evaluate the risks of using them as filtering media. Three polypropylene filters with different lengths (25, 60, and 100 cm) were constructed and fed with the same raw synthetic water. In-line coagulation was applied by addition of aluminum sulfate (22.5 mg·L−1) and filtration rates from 20 to 80 m·h−1 were evaluated. Filtrates with less than 0.5 NTU could be produced by both 60 and 100 cm filters, operating at 80 m·h−1. High filtration rates, as well as significant backwashing water and air flows, could be applied to flexible fiber filters made of polypropylene, which shows their promising applications.
Abstract
The recently developed flexible fiber filters (3Fs) are modular filtration units, which can satisfactorily remove solids at high filtration rates. Normally built with polyamide fibers, it is ...supposed that natural fibers can be used alternatively. This paper evaluated the performance of 3Fs using as filtering media sisal fibers in lieu of the polyamide ones. The sisal fibers were evaluated by means of scanning electronic microscopy and through solubility assays in hydrochloric acid and sodium hydroxide. Six filters with 28 mm of internal diameter were built, varying their length (25, 60, and 100 cm) and porosity (85 and 93%). The filtration system was fed with synthetic water, in-line coagulation was applied by the addition of 22.5 mg/L of aluminum sulfate, and filtration rates from 20 to 80 m/h were evaluated. Only the filter with 100 cm of length and 85% of porosity could work within the limit established (1 NTU), operating at 20 and 40 m/h. For all the studied configurations, the pressure drop was considerably low (less than 0.5 mH2O) when compared with 3Fs built with polyamide, which shows the potential of using this kind of filter as pre-filtration units or for less restrictive uses. This study showed that 3Fs can be adapted to include different configurations and materials, reducing their cost and making them appropriate for low-income countries.
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