However, new research shows the wetlands also harbor a health risk. In a new study<\/a>, my research group<\/a> found that just below the surface of subalpine wetland soils, the perfect conditions exist for the production of methylmercury, a potent, toxic form of the heavy metal mercury that can threaten the health of wildlife and people<\/a>.<\/p>\n As rising temperatures thaw ice and erode the mountain rocks<\/a>, and mercury pollution from power plants around the world falls with rain<\/a>, this toxic form of mercury can be produced in the wetlands.<\/p>\n A map shows the distribution of subalpine wetlands in the Boulder Creek Watershed, outlined in black. The wetlands have mosses, sedges and shrubs, and they are surrounded by evergreen trees. The Goldilocks problem<\/p>\n Methylmercury is a neurotoxin that biomagnifies and bioaccumulates<\/a>, meaning it becomes more concentrated as it moves up the food chain. Predatory birds and fish high on the food chain are most susceptible to its devastating effects on the nervous and reproductive systems, as are the human populations that consume them<\/a>.<\/p>\n In the 1950s, hundreds of people in Minamata and Niigata, Japan, died from methylmercury poisoning connected to ingesting water, fish and shellfish from near where chemical plants were discharging mercury into the water<\/a>.<\/p>\n Mercury methylation is a fickle process. The bacteria involved<\/a> require sources of inorganic mercury and energy, as well as oxygen-free conditions.<\/p>\n Sulfate concentrations are particularly important. Like in \u201cGoldilocks and the Three Bears<\/a>,\u201d too much or too little sulfate is unsatisfactory to the methylating microbes \u2013 those creating methylmercury. Too little sulfate, and they won\u2019t stimulate mercury methylation. Too much sulfate, and mercury gets sequestered in mineral form, minimizing its risk to living organisms.<\/p>\n The highest concentrations of methylmercury are produced when sulfate concentrations are in the Goldilocks zone: not too high or too low, but just right. Yet, when moderate sulfate concentrations mix with inorganic mercury and organic carbon in a low-oxygen environment, the conditions are dangerously \u201cjust right,\u201d as Goldilocks would say, and methylmercury production is high.<\/p>\n New evidence of methylmercury<\/p>\n Prior to our study, most wetlands found to have methylmercury pollution were in lowland areas, such as the Florida Everglades<\/a>, where the process is fed by sulfate runoff from agriculture fields<\/a>. However, our study demonstrates that methylmercury production occurs in seemingly remote mountain locations, too.<\/p>\n There are a few reasons why conditions in Colorado\u2019s subalpine wetlands are just right.<\/p>\n First, the soil has ample organic matter, providing a deep store of energy in the form of carbon to fuel methylation. In Colorado\u2019s subalpine wetlands, thick soils are rich in layer upon layer of ancient organic matter<\/a> that saturates with snowmelt flowing from the highest peaks. <\/p>\n Second, mercury pollution from industrial centers reaches the Rocky Mountains. Most of the mercury that enters subalpine wetlands has actually traveled all the way from China and India<\/a>. Eventually, it falls out of the atmosphere in rain or dust, and high elevations receive more of it than low elevations<\/a>.<\/p>\n Third \u2013 and this is the key stimulating effect for methylating bacteria \u2013 subalpine wetlands receive excess sulfate from warming alpine areas in elevations above them. As rising air temperatures drive the thawing of ice and quicker rates of mineral weathering<\/a>, more sulfate than was already in the ground flows into streams to the subalpine region.<\/p>\n The result is that these ingredients mix in the flooded, often oxygen-free environment of the wetland soils, and bacteria have everything they need to produce methylmercury.<\/p>\n Our study showed that the concentrations of methylmercury are higher at the outlet than the inlet of subalpine wetlands that we studied in the Colorado Rockies, providing further evidence<\/a> that wetlands can be a source of the contaminant.<\/p>\n Apart from the local effects of methylmercury on wildlife, our discovery highlights a concern for water supplies. Over 3 million people in the Boulder-Denver metropolitan area rely on clean, fresh water from the mountains. Contamination of the source area by methylmercury may have large-scale ramifications, such as costly treatment measures, for the entire Colorado Front Range\u2019s drinking water supply. <\/p>\n How to lower the risk<\/p>\n High-elevation ecosystems around the world<\/a> are experiencing many effects that can feed the production of methylmercury.<\/p>\n![\"Images](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2025\/08\/file-20250701-56-8b24wb.png\")
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\n Eve-Lyn Hinckley\/University of Colorado<\/p>\n![\"A](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2025\/08\/file-20250807-66-j5l23q.png\")
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\n Eve-Lyn Hinckley\/University of Colorado<\/p>\n