2023-05-16 04:31:12
Specialists from the Faculty of Natural Sciences and Museum (FCNyM) of the National University of La Plata study the growth of cyanobacteria -microscopic organisms- in the Río de la Plata and its impact on human health. They are currently working on the development of a system that serves to monitor their appearance and alert the authorities to take prevention and sanitation measures. These substances expand each year and affect the water intended for people’s consumption and recreation.
Ricardo Echenique, a researcher at the Buenos Aires Province Scientific Research Commission, maintains that cyanobacterial blooms are repeated every year. However, there are seasons where the density is higher, due to increases in average temperature, drought, the effects of agrochemicals and the mismanagement of sewage effluents. “In November 2020, an event of such magnitude occurred that it caused a temporary cut in the water supply in the regions of La Plata and the Autonomous City of Buenos Aires,” he points out.
As long as the droughts and high temperatures are repeated, the algae blooms could be more frequent and intense. “Historically, microalgae tend to appear towards the end of October, get stronger in December, January and February, and decrease in intensity from March onwards”, explains the researcher. Nevertheless, in recent years they were observed from September to June.
toxins that flourish
In the Río de la Plata, the species of cyanobacteria that produce the most blooms are those of the genus Microcystis, with toxins that affect the liver and can cause gastroenteritis, diarrhea, vomiting, and nausea. Others can generate neurotoxins, which cause neurological problems, dizziness, and breathlessness. In addition, there is a third group that produces allergies, skin problems, respiratory and eye complications.
“Although the amount of toxins in drinking water is very low, there are times when the levels are high and the purification processes should be complemented with other treatments and even interrupt the supply to the population from that source and replace it with another that offers less risk”, describes the researcher. Along these lines, he notes that in the La Plata region odor and taste in the water were reported associated with species of microalgae that produce geosmin, a volatile odorous metabolite.
In addition to the problem related to drinking water, Echenique refers to recreational water. “Together with the Undersecretary of Water Resources we designed a traffic light that warns about the different concentrations of cyanobacteria in the river. In the summer we find high levels in places like Punta Lara, Magdalena and Punta Indio, and we warn that people should not bathe, fish and do other water sports”.
The recreational water problem is that when a person swims, they indirectly ingest water. The same thing happens when they play on the beach or do activities like jet skiing and windsurfing. In these cases, droplets contain cyanotoxins that can enter through the nose and into the lungs and from there into the bloodstream. The risks of poisoning are multiplied and the situation worsens when the levels of cyanobacteria are high and are added to contaminants such as hydrocarbons, heavy metals and bacteria that can cause diarrhoea.
large scale studies
During 2020 and 2021, the FCNyM monitored the development of blooms in the Río de la Plata with satellite images based on a call from the Undersecretary of Water Resources of Buenos Aires together with other institutions. “At that moment IWe integrated an inter-institutional table together with Echenique and Nora Gómez (Secretary of Environment and Conservation of Natural Resources of the UNLP) for approach the problem from multiple facets”, says Silvia Sala, Head of the Phycology Division of the Museo de La Plata.
As a consequence of this exchange, two lines of research arose. On the one hand, they worked on aspects of the field and took water samples to analyze them and determine the presence of harmful species. On the other hand, developed a project to collect historical field information at the regional level and dump it into a Geographic Information System (NEXT). “We need to recover these data and do long-term research to understand this biological phenomenon in detail,” he adds. These tools are added to the monitoring carried out by the Water Authority, a Buenos Aires entity in charge of its periodic evaluation.
Anabel Lamaroa researcher at the Phycology Division of the Museo de La Plata and a professor at the UNLP, maintains: “With the GIS we intend to provide tools to management authorities for decision-making to collaborate with the monitoring of blooms”.
images that give away
From this initiative a database is designed where information on cyanobacterial bloom events is collected and standardized, to which data on land use, climate and river currents can be added. Thus, it is expected to better determine which are the variables that announce a possible event of these characteristics.
For its study, images from the Sentinel 2, Spot and Landsat missions are used. The expectation for the future is to add information from the SABIA-Mar satellite, which will provide knowledge about the sea and the coasts of Argentina. “This satellite is designed to measure, according to the properties of our waters and our coasts, and can be used for the problems of the Río de la Plata”, indica Sandra Torrusioprofessor of the Chair of Remote Sensing of the UNLP.
Recently, this academic unit released a high-resolution image of the French Spot mission (provided by CONAE), captured on February 9 over the Río de la Plata. There, a large spot in green tones is observed, indicating the presence of cyanobacteria on the coast, between the cities of Buenos Aires and Magdalena, and a more widespread bloom 20 kilometers inland.
“This vision offered by the Spot mission allows us to see practically the entire width of the Río de la Plata and our coastal zone, observe the extent of the bloom in all its dimensions and see how the algae are distributed in relation to the water currents”, highlights Lamaro.
“These blooms are sequential phenomena. They occur when environmental conditions are favorable, as occurred in 2020 and in previous years. With the information we are collecting We hope to predict their appearances, having predictability for making decisions that allow us to reduce the impact on the body of water and the population.”, emphasizes Echenique.
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