2023-12-12 19:04:32
Burned chaparral in the McLaughlin Nature Reserve in 2020. – ALANDRA LOPEZ
MADRID, 12 Dic. (EUROPA PRESS) –
Forest fires can transform a natural element in the soil into a carcinogenic metal and easily transportable by air known as chromium 6, Stanford scientists reveal.
Published in Nature Communications, research documents high levels of a dangerous form of metallic chromium at wildfire sites with chromium-rich soils and certain types of vegetation compared to adjacent unburned sites. Known as hexavalent chromium or chromium 6, This is the same toxin made famous by the 2000 film Erin Brockovich.
“Our study suggests that much more attention should be paid to wildfire-modified chromium, and we assume there are additional metals as well, to further characterize the overall threats that wildfires pose to human health,” he said. it’s a statement the study’s lead author, Alandra López, a postdoctoral researcher in Earth systems science at the Stanford Doerr School of Sustainability.
Smoke plumes from wildfires are known to carry dangerous air pollutants, including gases, organic aerosols and fine particles, which can cause asthma attacks, heart attacks and premature death.
Scientists and regulators have focused less attention on the potential harm from metals like chromium, which is common in soils in the western United States, Australia, Brazil, Europe, Indonesia and South Africa. As wildfires are expected to become more frequent and severe due to climate change, it will be necessary better understand the health risks posed by airborne chromium to firefightersdownwind residents and other people, the researchers said.
“In the complex mixture of gases and particles that forest fires spew in the form of smoke and leave behind in the form of dust, “Heavy metals like chromium have been largely overlooked,” said study lead author Scott Fendorf, Terry Huffington Professor at Stanford’s Doerr School of Sustainability.
In nature, chromium primarily occurs in a form known as trivalent chromium or chromium 3, an essential nutrient that our body uses to break down glucose. Chromium 6, which increases cancer risk when inhaled or ingested through contaminated drinking water, is often the result of industrial processes. Historically, high levels of chromium 6 have entered the environment through industrial runoff and wastewater.
Although natural chemical processes can trigger this transformation, laboratory experiments led by researchers at Australia’s Southern Cross University provided evidence in 2019 that chromium 6 could also form rapidly from chromium 3 in surface soils heated by wildfires.
Intrigued by these findings, Fendorf and López set out to test the theory that wildfires can leave soil contaminated with chromium 6. Focusing on California’s North Coast Range, they identified sites in four ecological reserves that have recently burned in soils formed from soils formed with naturally chromium-rich rocks such as serpentinite.
López collected soil from reserves and separated the smallest particles, which are the most sensitive to wind transport. He measured hexavalent chromium concentrations in this ultrafine dust from burned and unburned areas, and collected data on local fire severity and predominant soil, underlying geology, and ecosystem types, ranging from open grasslands to dense forests.
The researchers found that all of these factors influenced chromium-6 levels in the soil. Most dramatically, in chromium-rich areas where vegetation allowed fires to burn at high temperatures for prolonged periods, toxic chromium concentrations were approximately seven times higher than in unburned areas, suggesting that significant amounts of chromium 6 could be airborne.
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