Humanity’s use of coal, metals and other natural resources is making the planet more acidic, warns a new study that’s billed as the first of its kind.
Earth may be overdosing on acid — not the “turn on, tune in, drop out” kind, but the “kill fish, kill coral, kill crops” kind. And it’s shaping up to be a very bad trip.
ACID TEST: Corrosive discharge flows into a “rare earth lake” from a plant that processes rare earth metals near the village of Xinguang in Baotou, Inner Mongolia of China. (Photo: ZUMA Press)
The problem isn’t just acid rain or ocean acidification, either: pH levels are plummeting all over the planet, according to a new study by the U.S. Geological Survey and the University of Virginia. The origin of all this acidity, the researchers report, is humanity’s growing use of natural resources such as coal, metal ores and nitrogen.
Scientists have long known that certain chemicals can acidify soil and water when released en masse into the environment; sulfur dioxide and nitrogen oxides contribute to acid rain, for example, while carbon dioxide is widely blamed for causing ocean acidification.
In their new study, though, the USGS and UVA researchers report that a worldwide acid wash is now being fueled by a variety of human activities, namely “the mining and burning of coal, the mining and smelting of metal ores, and the use of nitrogen fertilizer.” This is dramatically reducing pH levels not just in soil and seawater, they report, but also in streams, rivers, lakes and even the air.
Each of these activities contributes to rising acidity in its own way, the study’s authors explain. Much of the CO2 emissions from coal burning are absorbed by ocean water, for instance, producing carbonic acid that wreaks havoc with marine food webs. SO2 from both coal burning and metal smelting leads to acid rain, which in turn acidifies soil and freshwater and can directly kill plants. Drainage from coal mines also boosts acidity in soil, freshwater and groundwater, while nitrogen added to farmland can reduce soil pH over time, limiting its ability to sustain crops.
In a press release issued Friday, USGS scientist and project leader Karen Rice calls the study the first of its kind, and says it can help other scientists and policy makers tackle the planet’s acid problem. “We believe this study is the first attempt to assess all of the major human activities that are making Earth more acidic,” she says. “We hope others will use this as a starting point for making scientific and management progress to preserve the atmosphere, waters and soils that support human life.”
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The study, titled “Acidification of Earth: An Assessment Across Mechanisms and Scales,” was published in the journal Applied Geochemistry.