Isotopes of nitrate and gadolinium fingerprints to assay human inputs in Guarani Aquifer System.

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 (15NNO3 and 18ONO3) 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., δ18ONO3 e δ15NNO3, 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.

Pollution threat to water and soil quality by dumpsites and non-sanitary landfills in Brazil: A review.

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.