Rivers like this one in Shenadoah National Park, Va. show signs of elevated acidity when compared to regional acidity levels 200 years ago.
credit:
Karen C. Rice, USGS
Nitrogen fertilizer application by country in 2008
credit:
USGS
Coal consumption by country in 2009
credit:
USGS
(Editor’s note: EarthFix Conversations makes its debut today. Listen by clicking the audio play button to the right and read on for the transcript of reporter Ashley Ahearn’s interview with two environmental scientists.)
The earth is acidifying, according to a new study from the U.S. Geological Survey and University of Virginia.
Human activity such as mining, smelting, burning coal and using nitrogen fertilizers are lowering the planet’s pH.
In this EarthFix Conversation Ashley Ahearn talks with the study authors: Karen Rice of the U.S. Geological Survey and Janet Herman, a professor in the department of Environmental Sciences at the University of Virginia.
EarthFix: Janet, let’s start with you the world is acidifying. How do we know this?
Herman: Well, we measure things (laughs). I know, it sounds pretty straight forward. We measure stream water and among the properties that we measure include pH. We measure rainfall chemistry including pH. We monitor the ocean, various portions of the world and in fact we even monitor soils to some degree. So in a longterm monitoring sense we have good evidence that the atmosphere, freshwaters, the ocean water, soils are all generally acidifying.
EarthFix: Karen, are some parts of the planet more acidic than others?
Rice: Yes some parts of the planet are naturally more acidic than others and parts of the planet are more acidic than others because of human influences.
EarthFix Conversations bring scientists right to you. What’s their research telling us? How will it affect you? Drop us a line with your questions or post them in the comments section and we’ll see that they get answered.
EarthFix: So you did some mapping for this paper can you tell me a little bit about what it looks like?
Rice: The maps are very interesting to look at in total. What we did is we looked at coal consumption by country. We looked at copper production by country, copper smelting by country as well as nitrogen fertilizer application by country and in very general terms we can say that the countries that are causing acidification or doing the most to contribute to acidification are also receiving their own inputs and the effect is local but it also is regional and for example in the case of carbon dioxide that is a global effect.
EarthFix: Janet, how much more acidic is our planet now than it was in the past?
Herman: We know that during periods of time in the past our planet was quite different than it is today. There were periods of intense volcanic eruptions in which some of these strong acids - nitric acid, sulfuric acid - were released to the atmosphere and as a result surface waters were more acidic than they would be during a time of less volcanic activity. Also geologically over time there have been periods of high carbon dioxide content in the atmosphere and the rock record tells us that the ocean was more acidic at certain times in the past relative to now. But what we were able to focus on was really this dramatic impact of human resource exploitation that goes beyond any sort of natural phenomenon. We have measurements that convince us that the earth’s surface environment today – it’s atmosphere, it’s waters, it’s soils – are more acidic than they were on the order of 200 years ago.
EarthFix: So play this out for me. If this trend continues you know, more acidic oceans, more acidic soils, what’s this going to look like? What’s the planet going to look like 50 years, 100 years down the line?
Herman: On the one hand I have some hope that with appropriate technology and regulations we don’t have to look forward to a wasteland of acidified watersheds. On the other hand, given that no individual nation has total control over acidifying the ocean. Given that there’s not a whole lot international attention on taking action to obviate the acidification of the ocean, I think it’s at real risk and the dire scenario could be a collapse of the food web in the marine ecosystem upon which so many people depend for food. So I’d say the potential consequences are dire and we need a more cooperative international look at appropriate regulations for these human activities.
Karen Rice is with the U.S. Geological Survey and Janet Herman is an environmental sciences professor at the University of Virginia.
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