Metals and limnological variables in an urban reservoir: compartmentalization and identification of potential impacted areas

Abstract

Reservoirs in urban areas are used for different purposes and are liable to different types of pressures that can cause the loss of chemical and biological quality, hence diminishing their ecological, economic, and cultural benefits. Here, a study of surface water heterogeneity was undertaken at the Guarapiranga urban reservoir (São Paulo, Brazil) in order to improve understanding of the structure and functioning of these ecosystems. Sampling was performed during the dry and rainy seasons at 33 sites. Limnological variables and total contents of the metals cadmium, nickel, lead, and zinc were analyzed. The risks associated with the metals were evaluated based on the toxicity unit approach. A principal component analysis enabled differentiation of the reservoir into six different areas. Some of the most powerful discriminatory variables (nutrients and metals) showed the existence of anthropogenic impacts on the system. The most strongly affected compartments were located in the following: (1) upstream area, under the influence of the Parelheiros stream, with the highest total phosphorus levels (318 mg L) and (2) dam area, with high values for total nitrogen, suspended organic matter, total solids, and pH. The results for the dam compartment were a consequence of substantial urbanization and a longer residence time. Despite high levels of cadmium during the rainy season, no significant potential risk for zooplankton was observed. The data indicated the need to control unauthorized land occupation and to implement adequate sanitation in the Guarapiranga watershed. This research provides information that should assist water resource agencies in the sustainable management of urban reservoirs.

Higher Abundance of Sediment Methanogens and Methanotrophs Do Not Predict the Atmospheric Methane and Carbon Dioxide Flows in Eutrophic Tropical Freshwater Reservoirs

“…The study area comprised the Guarapiranga ( 23 Brazil), an area with notorious importance since their main function is water supply (Pires et al, 2015). These three tropical freshwater reservoirs are eutrophic, due to the discharge of raw or inefficiently treated sewage (Cardoso- Silva et al, 2014Silva et al, , 2017. In each reservoir there were five sampling campaigns throughout 1 year, covering five hydrological periods: two wet seasons (summer Feb/2018 and Jan/2019), a dry season (winter Aug/2018) and two intermediate seasons (autumn May/2018 and spring Nov/2018).…”

“…All gas, water and sediment samplings were performed in situ, with locations reached by small boats in two subsequent days in each period. There were eleven sampling stations (Figure 1), Guarapiranga (G1, G2, G3, and G4), Billings (B1, B2, B3, and B4), and Rio Grande (R1, R2, and R3) selected according to a compartmentalization pattern proposed beforehand (Cardoso- Silva et al, 2014Silva et al, , 2017…”

Qualidade das águas de três reservatórios para abastecimento público na região metropolitana de São Paulo (RMSP)

“…Este aumento é consequência do maior aporte de nutrientes da bacia de drenagem ao corpo hídrico característica comum do período chuvoso (Smith et al. 2014;Cardoso-Silva et al. 2018).…”

Aplicações da Diretiva Quadro da Água da União Europeia na avaliação do estado químico do reservatório Paiva Castro (Mairiporã, SP): uma experiência brasileira

“…Não Tóxico Tóxico poucos estudos científicos publicados para o reservatório Paiva Castro (Cardoso- Silva et al, 2016a;Cardoso-Silva et al, 2016b;Beghelli et al, 2016;Cardoso-Silva et al, 2017;Pompêo et al, 2017;Cardoso-Silva et al, 2018) principalmente no que se refere à análise toxicológica (Silva, 2013). Apenas caracteriza o ambiente como eutrófico (Cunha et al, 2011) com frequentes florações de algas (Cunha et al, 2011;Cardoso-Silva et al, 2014).…”

“…Quando a qualidade da água é avaliada tendo como base os parâmetros de qualidade apresentados na Resolução Conama n° 357/2005357/ (Brasil, 2005, é extremamente comum observar que as massas de água se encontram em não conformidade ao enquadramento e em classe menos restritivas do que a classe na qual o corpo hídrico foi enquadrado como observado nos mananciais Billings (Cunha et al, 2011;Cardoso-Silva et al, 2014) e Guarapiranga (Machado et al, 2016;Cardoso-Silva et al, 2018). É comum também que uma massa de água enquadrada como Classe 4, por exemplo, a de uso menos restritivo e considerada de pior qualidade, poderá permanecer por décadas nessa condição, sem perspectivas de alteração seja da sua qualidade ou de seu enquadramento para classes de uso mais restritivo.…”