Overall Conclusion

By analysing the results achieved from the three experiments, a clear and coherent conclusion may be drawn.

In the Chemistry section, where the pH was tested, the average pH for the Lagoa Rodrigo de Freitas was of 8.75 and for Ipanema beach, the value was of 7.25. As the Ipanema beach's value is much closer to the expected value of a clean water, with few impurities and the value for the Lagoa may be considered significantly high, the results led to believe that the Lagoa's water was obviously more polluted.

In the Physics section, where density and refractive indexes were tested, the sample containing water from the Lagoa turned out to be denser and thus have a larger refractive index, whereas the sample with water from Ipanema was less dense, more similar to pure water, given the fact that seawater and not fresh water was being dealt with. Since a higher density means more impurities, the conclusion drawn from this experiment was also that the Lagoa's water was more polluted.

Last but certainly not least, the Biology section provided the group with the final, visual and more concrete proof to reach a final conclusion. From the final samples, the petri dish containing water from the Lagoa presented a much larger bacterial growth than the one with water from the Ipanema beach and with this, the same conclusion as the other experiments was reached: the Lagoa's water was more polluted.

Therefore, one can safely affirm that, through these three comparisons, the Lagoa's water is certainly of a lower quality and thus has a higher level of pollution. However, it is certainly not correct to affirm that the water from Ipanema is clean. It is simply cleaner than the Lagoa, but also suffers from the same problem and much has to be made to finally solve it.