From a press release issued by the United States Geological Survey:
Human use of Earth’s natural resources is making the air, oceans, freshwaters, and soils more acidic, according to a U.S. Geological Survey – University of Virginia study available online in the journal, Applied Geochemistry.
This comprehensive review, the first on this topic to date, found the mining and burning of coal, the mining and smelting of metal ores, and the use of nitrogen fertilizer are the major causes of chemical oxidation processes that generate acid in the Earth-surface environment.
These widespread activities have increased carbon dioxide in the atmosphere, increasing the acidity of oceans; produced acid rain that has increased the acidity of freshwater bodies and soils; produced drainage from mines that has increased the acidity of freshwater streams and groundwater; and added nitrogen to crop lands that has increased the acidity of soils.
The United States Geological Survey: Earth’s Acidity Rising – Major Causes and Shifting Trends Examined to Guide Future Mitigation Efforts
(via Doc Searls)
You can find the study here (I’ve not read it).
A few thoughts, assuming this study, and the description of i, is accurate:
1) I’ve argued for a while that even if global warming isn’t real, or if humans aren’t causing it, most of the tasks associated with trying to slow or stop it are still worth while (see: What If We Created a Better World for Nothing?). This study seems to confirm that.
2) I was skeptical about the value of organic farming, but this essay by Manuel Delanda convinced me that there is value there, if nothing else, in reducing dependence on external sources for fertilizers, therefore creating more resilience for organic farms (but I still think it’s an overhyped, poorly defined term mostly used by large corporations to bilk customers into paying more for food). This study presents another reason to reduce the use of nitrogen fertilizers.