How much do we know about the groundwater quality and its impact on Brazilian society today?

Abstract

Groundwater is an essential resource for society and the environment in Brazil. More than 557 m3/s (17.5 km3/y) are extracted through 2.5 million wells to meet demand in cities and the countryside, generating an economy of R$ 56 billion per year (US$ 14 billion/year). The aquifer has a remarkable function in the hydrological cycle because its large storage regulates the perenniality of rivers, lakes and preserves mangroves, marshes, and vegetation in dry periods. Aquifer discharges maintain between 24% (annual average) and 49% (dry season) of the flow of these surface water bodies. Although studies on groundwater quality are still restricted, it is known that most aquifers still preserve their excellent natural quality. Nevertheless, over the past years, there has been a growing increase in cases of contamination associated with: (i) natural geochemical anomalies (iron, manganese, and fluorine, secondarily, chromium, and barium, and rarely arsenic) due to the dissolution of specific minerals; and (ii) human contaminant activities, related to urban areas without sewage network, or with industrial activities, storage of hazardous products, and solid waste facilities. Among the anthropic compounds commonly handled, the most problematic are the chlorinated organic solvents and heavy metals, and in non-sewage areas, nitrate. The precarious knowledge of aquifer-quality, especially in cities, demonstrates the need to invest in regular and systematic hydrogeological research and mapping projects that drive to the improvement of the practices on aquifer quality protection.

Editorial: Freshwater sustainability and aquatic ecology in a fast-changing world

“…Likewise, groundwater degradation is also a current issue. Hirata & Suhogusoff (2019) highlighted that aquifers have remarkable functions in the hydrological cycle, regulating the perenniality of rivers and lakes and preserving mangroves, marshes, and vegetation in dry periods. However, there has been a growing increase in groundwater contamination with anthropic compounds such as chlorinated organic solvents, heavy metals, and nitrate.…”

Support method for interpretation of regional groundwater monitoring in urban areas

“…Equally important, various urban activities transfer immense amounts of matter from the atmosphere (Babinski et al 2003(Babinski et al , 2012 and from the surface to the soil (CETESB 2013, Santos Filho et al 2017, Aranda et al 2019, rivers (Porto 2003, Xu et al 2019, and aquifers (Foster and Hirata 1988, DAEE 2012, Cary et al 2013, Conicelli 2014, Petelet-Giraud et al 2018, sometimes contaminating them. In this urban cycle of water, energy, and matter, one of the rarely researched components is the aquifer (Foster et al 2011, Hibbs and Sharp 2012, Hirata and Suhogusoff 2019, even in countries in Europe and North America.…”

“…The best way to reduce the nitrate contamination risk in urban aquifers is to construct sewer networks, whose service reaches more than 38 million of the São Paulo population (88.4%) (SNIS 2017). However, leaks from the sewer mains are responsible for extensive contamination in unconfined aquifers (Hirata et al 2015, Hirata and Suhogusoff 2019, Varnier et al 2019, which is worrisome, especially when 80% of the state cities state have total or partial public water supply from groundwater, in addition to the existence of hundreds of thousands of private tubular wells that are extensively used.…”