Monitoring water quality is an essential tool for the control of pollutants and pathogens that can cause damage to the environment and human health. However, water quality analysis is usually performed in laboratory environments, often with the use of high-cost equipment and qualified professionals. With the progress of nanotechnology and the advance in engineering materials, several studies have shown, in recent years, the development of technologies aimed at monitoring water quality, with the ability to reduce the costs of analysis and accelerate the achievement of results for management and decision-making. In this work, a review was carried out on several low-cost developed technologies and applied in situ for water quality monitoring. Thus, new alternative technologies for the main physical (color, temperature, and turbidity), chemical (chlorine, fluorine, phosphorus, metals, nitrogen, dissolved oxygen, pH, and oxidation–reduction potential), and biological (total coliforms, Escherichia coli, algae, and cyanobacteria) water quality parameters were described. It was observed that there has been an increase in the number of publications related to the topic in recent years, mainly since 2012, with 641 studies being published in 2021. The main new technologies developed are based on optical or electrochemical sensors, however, due to the recent development of these technologies, more robust analyses and evaluations in real conditions are essential to guarantee the precision and repeatability of the methods, especially when it is desirable to compare the values with government regulatory standards.

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in 2020 led to a significant change in human behaviors, mainly because of the quarantine to avoid the spread of the virus. Measures affected both economic activities and citizens’ behaviors as they developed more intense hygiene habits to avoid contamination and switched to home offices. These exceptional behaviors also affected the way that water is consumed and need to be fully understood to manage supply systems. Therefore, this study aims to investigate changes in residential and commercial water consumption in 31 municipalities in the state of São Paulo, Brazil, during SARS-CoV-2. To do this, the expected consumption for the first half of 2020 was forecasted using the Holt-Winters multiplicative method and compared with the data observed for the same period. In addition, we compared monthly records of new contaminations and the social distancing index to establish a correlation with changes in water consumption. The results show an average difference between forecasted and observed consumption equal to $+6.23\%$ and $-18.59\%$ for residential and commercial activities, respectively. For the first one, the consumption per capita increased at the rate of ${8.44\mathrm{L}.\mathrm{person}}^{-1}{.\mathrm{day}}^{-1}$ . The observed changes in consumption seem to be a consequence of hygiene habits, social distancing and the closing of nonessential services in commerce.

Anais do II SUSTENTARE e V WIPIS - Workshop Internacional sobre Sustentabilidade, Indicadores e Gestão de Recursos Hídricos (978-65-5941-063-7) - Avaliação De Sustentabilidade Dos Indicadores Do Plano Das Bacias Hidrográficas Dos Rios Piracicaba, Capivari E Jundiaí

Tropical freshwater reservoirs are vital for water management but also contribute to greenhouse gas (GHG) emissions, making mitigation strategies crucial, especially in the Brazilian Northeast, where water scarcity and climate variability impact livelihoods and ecosystems. This semi-arid region depends on reservoirs due to irregular rainfall and high evaporation, with reforestation offering a promising means to offset emissions while supporting sustainable water management. We assessed the carbon footprint and offsetting potential of 24 small reservoirs in the region using the G-res tool under SSP2-4.5 and SSP5-8.5 climate scenarios. Results show that GHG emissions vary with water depth, climate, and land use, with smaller reservoirs often showing higher emissions. Expanding vegetation in catchments and around reservoirs can help offset emissions and enable blue-green transitions for climate change mitigation. Future reforestation efforts must increase significantly, requiring a 286% rise in forested areas compared with the reference period under the SSP5-8.5 scenario to fully offset emissions. By analyzing emissions from reservoirs and applying reforestation to reduce their carbon footprint, this study shows that (1) climate change and unsustainable transitions raise GHG emissions in tropical reservoirs, (2) reforestation can offset emissions and support sustainable management, and (3) future reforestation areas must expand under climate scenarios.