EGEE 102
Energy Conservation for Environmental Protection

Effects of Acid Rain



Pure water has a pH of 7.0. Normal rain is slightly acidic because carbon dioxide dissolves into it, so it has a pH of about 5.5. As of the year 2000, the most acidic rain falling in the US has a pH of about 4.3.

Below is a video demonstration that replicates the effect of acid rain on plant life. In this video, beans are placed in: a) water, b) slightly acidic water and c) acidic water, and their growth is observed over a period of three days. Please watch the following 5:35 video:

Effects of Acid Rain
Click Here for Transcript of Effects of Acid Rain video

We are learning about the environmental effects of acid rain. Acid rain is basically the compounds that form acid are mixing with the water in the clouds and coming down acidic rain. As it can be created at home using various day-to-day ingredients, one of them is vinegar, or you could use, also, lemon juice, that has a lot of acid. So what we are going to do in this demonstration today is to see the effect of acid rain on spouting off moon beans. These are a special kind of beans. And you can use, actually, most of the types of beans which have hard shell on the outside. So we are using here three different bowls here. Each of these bowls is filled with 20 beans, 20 seeds of these moon beans. And we are going to pour plain water in this one, and slightly acidic water in this bowl, and highly acidic water in this bowl, and see every day-- tomorrow, day after, and a day after that-- how this acid changes the spouting off these beans. So let's actually prepare this and add plain water to the first one. This is plain water, just water from the faucet. I'm going to add enough water so that these beans are all immersed in the water. Now the slightly acidic water I'm preparing by adding vinegar that I have here. And now this is a bottle of vinegar. And I'm going to add two spoons of vinegar to this. So this water in this cup is slightly acidic. I'm going to mix this and use this water. This is slightly acidic water. And I'm going to pour slightly acidic water in here. There are 20 beans in this cup, in this bowl, also. And I'm going to prepare highly acidic water here with the same vinegar. I'm going to add five spoons-- one, two, three, four, five. This is a little bit stronger than the other acid that we prepared. Now I'm going to add this highly acidic water to this bowl to the same level. And as the water evaporates, whatever type of water-- as the water evaporates, we need to refill with the same kind of water-- plain water in this bowl, slightly acidic water in this bowl. And highly acidic water in this bowl-- and observe the results. And what I want you to now hypothesize is which one would have the significant effects. Which one would have the significant effect? Or which one of these bowls will have more sprouting than the other? And when you look at day one, day two, day three, I need you to count the number of seeds that are sprouting. And you can prepare a plot. Let's say on day one, the plain water ones sprouted six out of 20, which means 30% have sprouted. Slightly acidic ones, four out of 20. So that's 25%. Highly acidic one, six out of 20. That's, again, 30%. So you can plot that as a function of time and see at the end of four or five days how many of these seeds sprout. Let's watch for three days. OK. We are on day three today. And you can see on day one itself we had all 20 out of 20 sprouted in this plain water. And slightly acidic water, we didn't have any sprouts. Even today, we don't have any sign of sprouting in highly acidic water. That is the impact that you can see of the acidity on sprouting of seeds. Now you can imagine what it would be like for the entire planet if it is covered with acidic rain. And what would be the impact on agriculture? What would be the impact on food supply chain to the humanity? So that is what we learned from this exercise.

Negative Consequences

Acid rain results in many negative consequences. Place your mouse over the image below to see the effects of acid deposition.