Temporal changes in the water quality of urban tropical streams: An approach to daily variation in seasonality

Abstract

Using water quality indices (WQIs) is one way to monitor watercourses for water quality. Currently, there is a lack of information about their behavior in the diurnal cycle because sampling is often carried out in the morning. Also, few articles focus on assessing the urban impact on the spatial variability of WQIs in tropical first‐order streams. Such streams receive many pollutants varying in intensity according to population habits, justifying the possible diurnal variation in water quality in addition to climatic attributes. This paper aims to evaluate the fluctuations in Brazilian WQIs and their parameters (temperature, turbidity, total solids [TS], hydrogen potential, dissolved oxygen [DO], biochemical oxygen demand [BOD], total phosphorus [TP], total nitrogen [TN], and Escherichia coli) between the morning (8 AM), afternoon (2 PM), and night (7 PM) periods for an urban first‐order tropical stream. Overall, the lowest DO concentrations and highest values of TS, turbidity, BOD, TP, TN, and E. coli were obtained in the morning, possibly representing population habits: the greatest generation of pollutants occurs overnight and in the early morning because there are clandestine domestic wastewater inputs into the stream, whose hourly periodicity generates a similar periodicity in the WQI of the evaluated stream. Although there was a significant variation in WQI average values between morning (15.50 ± 1.97) and afternoon (20.83 ± 5.42) only during the dry season (p < 0.05), different results were common throughout the day in all months, and the water quality was often classified in distinct categories: very bad, bad, and regular. Our findings present another dimension to be considered when assessing urban water quality, leading to direct benefits to the management and use of urban waters. Integr Environ Assess Manag 2022;18:1260–1271. © 2021 SETAC

Determination of the ecological water quality in the Orienco stream using benthic macroinvertebrates in the Northern Ecuadorian Amazon

“…Recently, there has been a great interest in refining water‐quality criteria in tropical regions because regions such as the NEA are prone to daily variation in weather, including high precipitation (Bega et al, 2021; Briciu et al, 2020; Nobre et al, 2020). Precipitation in the NEA region can range from 2800–4500 mm/year (INAMHI, 2020).…”

“…This could be improved in future studies in the NEA region by increasing the sampling throughout the year to include both the rainy and dry seasons. The need for better estimates of the water quality of watercourses has been recently reported (Bega et al, 2021; Briciu et al, 2020). For example, in a study assessing the variation in water quality variables in tropical first‐order urban streams in Brazil, the authors reported significant variation in water‐quality parameters throughout the day, resulting in distinct water‐quality classifications for the same stream (Bega et al, 2021).…”

“…The need for better estimates of the water quality of watercourses has been recently reported (Bega et al, 2021; Briciu et al, 2020). For example, in a study assessing the variation in water quality variables in tropical first‐order urban streams in Brazil, the authors reported significant variation in water‐quality parameters throughout the day, resulting in distinct water‐quality classifications for the same stream (Bega et al, 2021). Further, previous studies have also reported the influence of seasonal water on surface water quality in rivers (Briciu et al, 2020).…”

“…However, most of the time the Ecuadorian Ministry of the Environment (MAATE) and local governments fail to comply with water‐quality monitoring programs in isolated and rural places such as the NEA region (Barbieri et al, 2009; INEC, 2015; Varela, 2016). Furthermore, the water‐quality parameters only provide a snapshot of the ecological water quality of an aquatic system due to their fluctuations in measurements, which can impair the management and use of water (Bega et al, 2021; Wan Abdul Ghani et al, 2018).…”

Water consumption in the production process of the sugar-energy industry: case study in the northwest of São Paulo (Brazil)

“…Despite its importance for Brazilian economic development (regional growth and income generation through jobs and better working conditions), the sugar-energy agro-industry has always had its image linked to environmental damage (Loarie et al, 2011;Zhang et al, 2015;Jaiswal et al, 2017;Monteiro et al, 2018;Zheng et al, 2022). In the past, water resources were used extensively by the sector and the final disposal of the effluents generated was carried out, in most cases, without proper control, which can negatively impact the receiving water courses (Bega et al, 2021;Bega et al, 2022;Ribeiro et al, 2022). However, in the 1990s, the sector began to worry about the sustainability of its production processes amid the competitive market that emerged, strategically shifting to a more organized production model (Santos, 2009).…”