Climate Detectives Projects 2018-2019

Project title: Study of the effects of the pollution of Madrid city in the acidity of rainfall and soils in Tres Cantos

Team: Tsunami  LPS CD School Award

2018-2019   IES José Luis Sampedro   Madrid   Spain   10 Student’s age: 14-15

In this investigation we have studied the levels of contamination in Madrid and the harmful effects that these contaminants cause in our city, Tres Cantos in the North of Madrid. In order to do that, we have firstly studied the primary contaminants in the Community of Madrid. This contamination is made up of oxides, basically of sulfurs and nitrogen, that react with water vapor, forming nitric and sulfuric acids, which reach the ground in the form of acid rain. Our second step was to measure the pH and the presence of nitrates of the poured-down rain throughout five months. The precipitations of acid rain cause important damage in vegetation, apart from increasing the level of acidification of terrestrial waters and soils, which leads to desertification and the decrease in vegetation. In order to see these effects, we have designed two experiments: the creation of an enclosed ecosystem with contaminants present and the exposure of soil to artificially-made acid rain. Finally, we have analysed whether this process is causing desertification in the North part of Madrid through the analysis of the maps given by the EO Browser online tool from the Sentinel 2, 3 and 5P earth observation satellites. Firstly, we built a system to collect samples of precipitation with a buret. During six months, we gathered precipitation. We analyzed the pH and the nitrate levels of these samples, using pH-meters and a nitrate kit. Our results showed that after a long period without rain, the acidity and nitrate concentrations increased in the precipitations. Secondly, we simulated acid rain in two controlled soils (indoors and outdoors), watering them regularly during 6 months to measure the effects of the contaminated precipitations. Our experiment showed that vegetation was severely affected by the constant decrease in the pH of the test soils. We also built an enclosed ecosystem in which we simulated a polluted atmosphere and where we measured the effects of acid rain; by steadily increasing the temperature of the environment and measuring the pH and nitrate concentration of the soil. This way we have observed the devastating effects of the acid rain in ecosystems. Lastly, we studied the effects of contaminant substances in Madrid atmosphere over time in the vegetation coberture of Madrid (measured by satellites from EO Browser). We have observed that there is a correlation between the increase in contamination and a decrease in vegetation density.

With our experiments, we have seen how in an atmosphere contaminated with Nitrogen and Sulphur oxides they react with water vapor and form acid rain that can damage vegetation. We have also measured the effect of this acid rain in different testing environments, with the same results in all of them: an increase in the acidity of soil and the damaging of vegetation. We have observed that in our town, after a prolonged time without precipitations, the pH of rain decreases and the concentration of nitrates is higher. However, we have not observed acid rain (pH below 5). We think it is caused because our municipality is 20 Km away from the city of Madrid, the main source of contamination in the region. In conclusion, we think it is important to reduce the contamination in Madrid, to try to maintain non-acidic precipitations in the region. The increase in the average temperatures caused by the global climate change will make the effects of this contamination to become worse, speeding up the desertification of the region. To fight this desertification, we propose a system with biodegradable pots and hydrogels to recover the vegetation that has been damaged and regenerate the soil.

For reducing the effects of deforestation caused by acid rain on Tres Cantos, our town, we have proposed a solution based on a system of silica hydrgels, which absorb the water and nutrients and releases them as the plant requires them. The system consists of a byodegradable pot containing soil, the hydrogels and the plant. Over the plant we will put a boidegradable mesh that reduces the effect of acid rain on the soil, avoiding degradation of the soil.