An expedition carried out by the SOS Mata Atlântica Foundation, in partnership with several universities and research centers, identified that There is no stretch of the Tietê River that is completely free of contamination.
For the “Tietê 2025 Expedition”, held between June 9 and 14 last year, more than 1,100 kilometers of the entire river were covered — from its source in Salesópolis to the mouth, where it flows into the Paraná River —, with the aim of analyzing various water quality parameters.
According to the study, during the journey, microplastics were identified in all 14 points analyzedin addition to 25 types of pesticides and 16 substances among .
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The main conclusion is that Tietê presents multiple simultaneous layers of contamination: microbiological, chemical, pharmacological, plastic, agricultural and organic.
Pressures that vary along the way and directly reflect urbanization, insufficient sanitation, agricultural land use, the presence of reservoirs and changes in basin occupation.
“The river reflects the marks of sewage, daily consumption patterns, plastic waste, agricultural activities and land use and occupation in the river basin. When we find pesticides along the route and substances such as pharmaceuticals and illicit drugs in the water, we are not looking at separate problems, but at a set of pressures that act simultaneously and cumulatively”, says Gustavo Veronesi, spokesperson for SOS Mata Atlântica.
Pollutants found
Microplastics, present everywhere, ranged from 330 to 23,587 particles per cubic meterwhile the predominance of fibers points to sources such as domestic and industrial effluents, urban drainage, washing synthetic clothing and inadequate waste disposal.
The highest concentrations were recorded in urban areas, such as Osasco, and in interior reservoirs, such as Promissão, where the peak was recorded, as the dams function as retention zones and accumulate 10 to 17 times more particles than the current areas. In the international comparison, the levels observed in Tietê are below those of some Asian rivers and above those in European regions, which leads researchers to classify the system as having a moderate to strong impact.
According to the research, the 16 substances identified among pharmaceuticals and illicit drugs – including cocaine and its metabolite, benzoylecgonine, as well as carbamazepine, diclofenac and losartan – they function as chemical signals of human presence in the river. Caffeine, detected at all points, is consolidated as a marker of domestic sewage pollution.
Therefore, the recovery of the Tietê requires an integrated approach, which combines expansion of sanitation, effective inspection, territorial planning and continuous monitoring of environmental quality, involving the State, municipalities, river basin committees, industries, commerce, farmers and the population.
The 25 types of pesticides, out of a total of 46 compounds investigated, show that pollution in Tietê is not restricted to urban areas. In the Middle and Lower Tietê sections, the results indicate greater agricultural influence, associated with the cultivation of sugar cane, soybeans and citrus. Draws attention to presence of atrazinea herbicide banned in the European Union since 2004 and still widely used in Brazil, detected in Tietê above legal limits in some areas.
Physicochemical analyzes also showed metals above legal limits. Copper was detected in concentrations beyond what was permitted at all points analyzed, while aluminum exceeded the limit in several sections. In excess, These metals can be toxic to aquatic life and reinforce the need for continuous monitoring of water quality.
Biochemical diagnosis
The contaminants found reflect habits and consumption patterns of the population, functioning as a true “collective biochemical diagnosis” of São Paulo society. You
data microbiological tests indicate the presence of fecal bacteriapathogens, parasites and organisms associated with gastrointestinal diseases.
In the samples collected at the source, some indicators were above the legal limits for better quality rivers, reaching, in certain cases, up to 40 times what is permitted. Added to the detection of pharmaceuticals and illicit drugs, this condition makes the river an indirect indicator of the sanitary conditions and the occupation model of the territories it crosses.
According to Luís Fernando Guedes Pinto, executive director of the organization, the diagnosis points to the path to the solution. “Tietê’s pollution does not come from a single source and will not be resolved by a single measure. Recovering the river requires sanitation, inspection, territorial planning, changes in agricultural practices, forest recovery and continuous monitoring, advancing in an articulated manner throughout the entire basin and in the long term.”
*Under the supervision of Thiago Félix
