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.
Graphical Abstract
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.
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.
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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.
Parabens are preservatives widely used by industry since these compounds have antifungal properties, relative low cost, and stability over a wide pH range. This study aims to quantify and assess the ...environmental risks of methylparaben (MP), ethylparaben (EP), propylparaben (PP), and butylparaben (BP) in surface water from a Brazilian River, Mogi Guaçu. The State of São Paulo, including the Mogi Guaçu River region, suffered from a period of intense drought and high temperatures, which caused anomalies in river flows and water supply problems. The water samples were collected from 14 locations, along 300 km of river extension, at four different seasons. Samples were previously extracted and pre-concentrated by dispersive liquid-liquid microextraction (DLLME) and later analyzed by ultra-performance liquid chromatography coupled with electrospray ionization in tandem with mass spectrometry (UPLC-ESI-MS/MS) detector. During the sampling period, PP was detected in 89.3% of the water samples, MP in 87.5%, EP in 73.2%, and BP in 48.2%. The sum of parabens’ average levels was 42.2 μg L
−1
in Winter, 41.5 μg L
−1
in Summer, 36.6 μg L
−1
in Autumn, and 31.5 μg L
−1
in Spring. These levels can be attributed to the smaller dilution effect caused by the drought period. Also, ecological risk assessment indicated that parabens could take a low, medium, and high risk for target organisms in the measured aquatic environments, especially considering
Pimephales promelas
where 15% of the samples do not present potential risk, 84% of samples can present medium risk and only 1% have low risk. Besides, the risks for BP are also considerably higher, when almost 40% presents for high risks and 60% for medium risks. The present study indicates worrisome threats to the water source and to allegedly protected biodiversity and, therefore, urgent actions are needed to effectively protect.
Graphical abstract
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•The SWAT model supports better management of erosion processes.•Computational models can be used with methods of visual recording erosion.•Simple statistical models aligned to SWAT ...is adequate to analyze erosive processes.•The spatially distributed erosion identifies the susceptible areas to water erosion.
Water-driven erosion associated with the transport and deposition of sediments in watersheds may lead to contamination problems causing significant damage to land and infrastructure. The key factors that influence erosive processes are well known and include the precipitation rate, terrain topography, soil type, and vegetation cover. The soil and water assessment tool (SWAT) considers these factors and may be used to identify areas susceptible to soil erosion and to estimate soil loss and sediment transport and deposition. To corroborate this assumption, real data on rill erosion and sediment transport from the Mogi Guaçu River Basin in southeastern Brazil were used to validate SWAT estimates. The study shows that the model is able to identify soil-eroded areas and replicate the scale and variation patterns of sediment production, although not with great precision. Hence, it can successfully be used for prioritizing areas that require action and for evaluating alternative soil management and conservation practices to mitigate erosive processes.
The inadequate disposal of solid waste, a common practice in developing countries, can represent an important pollution source since the closure of these deposits typically does not include the ...adoption of monitoring, isolation, or remediation techniques. Even so, several disposal areas are abandoned, without performing long-term monitoring in order to evaluate the depletion of contaminants’ concentrations. This research aimed at comparing current and historical physicochemical data of water resources surrounding a non-sanitary landfill situated in a Guarani Aquifer recharge zone. The primary objective was to recognize whether significant changes in contaminants concentrations occurred, as well as if the area still poses a significant threat to the environment, 20 years after ending disposing activities. Samples from eight monitoring wells and three surface water points (upstream and downstream to the deposit) were evaluated in the periods of 1996–1997 and 2016–2019. The parameters pH, electrical conductivity (EC), alkalinity, chemical oxygen demand (COD), oxidation-reduction potential (ORP), chloride, nitrate, iron, manganese, calcium, and magnesium were investigated. Contamination has been detected in the landfill surroundings since the ending of the waste disposal (1996–1997), even though its intensity reduced within short distances from the waste mass. Nevertheless, no statistical variation occurred in 20 years’ time considering COD, chloride, calcium, magnesium, and ORP. Moreover, increases of EC, pH, alkalinity, iron, and manganese concentrations were observed for the years of 2016–2019. The results indicate that the evaluated contaminants do not suffer depletion in the surroundings of non-sanitary landfills in sandy aquifers, considering a time span of 20 years. This study also suggests that those areas need to be adequately remediated to permit other future land uses.
Improper landfills (waste dumps) are common waste disposal systems in developing countries and represent sources of environmental pollution. These sites defy researchers and managers because they ...lack structures to collect liquid, solid and gaseous samples, which make it challenging to monitor local environmental quality. In this work, we show one device for sample collection to monitor leachate quality in a closed waste dump in Brazil. During the installation of this device (Leachate Monitoring Station, LMS), interesting facts about the structural, physical, and chemical composition of an old dump could be visualized. Two different kinds of leachate were found: the accumulated leachate (AL), a thick dark fluid entrapped above non-degraded material, and the mobile leachate (ML), a lighter liquid which flowed into the LMS, and thus was not stagnant like AL. In the AL, the chemical oxygen demand and total ammoniacal nitrogen average concentrations were about 21,500 mg/L and 1000 mg/L, respectively, which were considerably higher than the ML concentrations, of about 1100 mg/L and 200 mg/L, respectively, for the same parameters. Thus, despite the lower concentrations of hazardous substances in the ML, the waste body stores pockets of leachate (AL) with significant concentrations of hazardous compounds, even after 15 years of the dumpsite closure. Moreover, waste solubilization assays showed that the solid material could not be considered inert according to the Brazilian Standard Norm NBR 10004/2004. The installation of the LMS enabled a new understanding about pollutant accumulation inside waste deposits and provided an effective, low-cost tool to monitor leachate production in non-sanitary landfills. The results warn about the risks that old dumpsites still pose to the environment and reinforce the need for a post-care action plan for managing uncontrolled waste deposits.
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