Introduction
Every “carioca” knows that the quality of the water in the Lagoa Rodrigo De Freitas, the city’s most famous lagoon, isn’t the best one, and is indeed appalling although studies have shown that the level of pollution has significantly decreased in the past few years. In the Ipanema beach, one of the most famous beaches in the world, which is in fact connected to the Lagoa Rodrigo de Freitas through the Jardim de Alah, as seen in the map, the quality of the water is obviously better. But a growing concern amongst the population of Rio de Janeiro is the increasing level of pollution that the beach overcame in the past few years due to innumerous reasons which will be presented later.
Therefore, in this project, the group consisting of 5 IB Experimental Science students aims to investigate the level of water pollution in these two famous spots of Rio’s beaches and salt water lagoons using different methods for each of the three branches of science: Physics, Chemistry and Biology. The group consists of two IB Chemistry students, Gabriel Fritsch and Lucas Biolchini, two IB Biology students, Jonas Adler and Ana Carolina Augusto and one IB Physics student, Olga Saadi, who will work together, each contributing in their own fields towards the project’s completion.
The way which the group chose to integrate the three sciences in testing the level of pollution of different samples of water was simple but led to much reflection. For the Chemistry part, it was decided that the acidity of the samples of water would be tested. The farther from pH 7, the higher the water’s level of pollution. To integrate Biology into the investigation, the water would be tested for bacteria and microorganisms and, last but not least, for the Physics part, the group decided to investigate the effect that impurities and different levels of salinity have on the process of refraction of light in water.
An in-depth explanation of each of the separate investigations, with methods of data collection and results will later be posted here in our blog. Now, let us know more about the two locations we are investigating.
Ipanema Beach
The city of Rio de Janeiro is the largest coastal city in Latin America and one of the largest in the world. It is globally known for its peculiar landscape, with huge mountainous structures being immersed directly into the city’s famous beaches, bays and lagoons. Ipanema beach is a famous example. However, the consequences of the pressure on the ecosystem due to the demographically dense metropolis are evident in the increased level of pollution that the water presents. This has specifically risen in the past 2 decades.
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| Visibly polluted water being carried between Ipanema Beach and the Lagoa. |
The main reasons for this are the “canais da maré”, the tide channels, which make the connection between lagoons and urban draining adjacent to the sea with the beach and the famous “línguas negras”, the “black tongues”, the underground plumbing system which carries rainwater and urban draining near the beach to the sea. Another significant source of pollution are the submarine emissaries which carries the urban sewage to areas farther from the coast, but which, given certain meteorological and oceanographic conditions, these polluted remains reach the Ipanema beach, thus further jeopardizing its water quality.
According to the CETESB (the Rio de Janeiro’s state Company of Environmental Sanitation Technology), the prolonged contact with the beach’s water, where the possibility of ingesting significant amounts of seawater is high, may indeed cause various types of diseases, including gastroenteritis, infections in the eyes, throat, nasal cavity and ears, dysentery, typhoid, cholera and many others. Studies have shown that in during the months where the rainfall is most concentrated, the water from Ipanema beach show high amounts of total coliforms and E.Coli.
Lagoa Rodrigo de Freitas
The Lagoa Rodrigo de Freitas is a common example of a salt water lagoon formed by the depoisition of sand due to a sudden change in the coast’s shape, which forms a bar beach, impeding its contact with the sea. However, the Lagoa as it is popularly known, is connected to the Atlantic, allowing sea water to enter, by a canal known as Jardim de Alah.
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| The Lagoa and its visibly dark, polluted water. |
For many years, the Lagoa has suffered with the harsh consequences of pollution. One of the main sources of this problem is the several illegal sewage disposal systems connected to the lagoon, which release several toxic substances into the lagoon’s water (studies have found high concentrations of heavy metals such as copper, nickel and zinc in the lagoons water, with values higher than the acceptable limits) and also generate a large nutrient stock which causes another problem: eutrophication. Due to the high level of nutrients, a rapid increase in microalgae production occurs resulting in a loss of the water’s transparency and increased oxygen consumption thus creating an oxygen deficit in the Lagoa’s water. The lack of oxygen significantly reduces wildlife as it kills many of the species which cannot carry out the necessary processes to survive with such a low level of oxygen. As these microalgae and other species decompose, an excessive amount of bacteria may be spotted.
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| Dead aquatic life due to toxic substances and eutrophication in the Lagoa. |
Similarly to Ipanema beach, the bacteria present in the Lagoa Rodrigo de Freitas’ water can cause all of the diseases aforementioned. A plan, made through a partnership between EBX, Eike Batista’s (the multi-millionaire Brazilian entrepreneur) company and the Rio de Janeiro City Government called Lagoa Limpa is being currently put into action which aims in depolluting the Lagoa and has already produced positive feedback that the quality of the water is indeed improving.
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