Mining Powers Modern Life, but Can Leave Scarred Lands and Polluted Waters Behind
By Matthew Ross
Modern society relies on metals like copper, gold and nickel for uses ranging from medicine to electronics. Most of these elements are rare in Earth's crust, so mining them requires displacing vast volumes of dirt and rock. Hard rock mining – so called because it refers to excavating hard minerals, not softer materials like coal or tar sands – generated $600 billion in revenues worldwide in 2017.
The Trump administration has revived several controversial mining proposals that previously were blocked or stalemated. They include the Pebble Mine at the headwaters of Alaska's Bristol Bay and leasing around Minnesota's Boundary Waters Canoe Area Wilderness. It also approved a large copper mine in southern Arizona, which was subsequently blocked by a federal court ruling.
I study human-altered landscapes, including areas impacted by mines. Mining operations are major water pollution sources and can cause problems that persist for generations. Their global footprints also directly reshape significant portions of Earth's topography, leaving indelible evidence of human presence.
Digging Deep and Wide
In most locations, concentrations of copper, gold and other elements are too low to be extracted profitably. But in some spots they occur in seams of mineable, high-concentration minerals called ores. The economically viable concentration of a mineral depends largely on its market price. Gold ore can be viable at concentrations as low as 0.0001%, while copper becomes uneconomic below 0.5%.
To reach these deposits underground, miners tunnel, dig open pits or scrape through the earth's surface. The choice of technique depends on factors including how consolidated the ore is, the geologic setting and the depth of the ore.
Deep mines disturb the smallest amount of surface land, but are inherently more dangerous for miners. Far below the earth's surface, crews constantly risk encountering toxic gas fumes or stale air with no life-giving oxygen. Other dangers include earthquakes and equipment failures. In 2010, 33 Chilean miners spent over two months trapped underground in a copper-gold mine after a ramp collapsed, but ultimately were rescued.
Growing international emphasis on mine safety and changes in technology and ore quality have prompted a shift from deep mining to pit mines or surface mines, which access ores from the open air. Pit mines can be up to three-quarters of a mile deep, but typically cover less than 20 square miles. In contrast, surface mines typically extend less than 1,000 feet into the earth's crust, but can extend over hundreds of square miles.
Along with metals such as gold, silver and iron, mines also produce materials including sand and gravel, crushed stone and Portland cement. USGS
Accessing ore typically involves blowing apart bedrock, removing it from the shaft or pit and storing waste materials nearby after extracting the ore. In these heaps of loose rock, known as spoil piles, previously buried raw minerals are exposed to air or water. Sulfur-rich compounds in the rock react with oxygen and water, producing sulfuric acid, which can lower the pH of nearby streams to levels comparable to lemon juice or vinegar.
At its worst this process, known as acid mine drainage, can kill most native aquatic life. If acid drainage reaches groundwater, it may persist for decades or centuries and start a cascade of other impacts that impair water quality throughout local river networks.
When acid mine drainage lowers a stream's pH, other metals can also start to melt out of minerals in spoil piles, mine shafts or adjacent soils, leaching into soil and groundwater that intersects these areas. This creates waters with increased levels of cadmium, copper, lead and other heavy metals, which are harmful to aquatic insects, fish and human health.
These effects can be transported far downstream and last for generations. Old and abandoned mines around the world have harmed water quality long after mining has ceased. Their impacts can come as long-term slow leakage, or as sudden discharges like the 2015 Gold King spill near Silverton, Colorado, which released three million gallons of mine wastewater and debris into the Animas River.
According to the U.S. Government Accountability Office, there are at least 161,000 abandoned hardrock mining sites in the U.S. West and Alaska. Of these, at least 33,000 have contaminated water supplies or left piles of mine waste contaminated with arsenic behind.
Altering the Planet's Shape
Mining operations have also left thousands of square miles of land altered. In some cases, particularly mountaintop removal mining, entire land forms are permanently reshaped. For millennia the planet's surface was configured by the slow geologic processes of wind and rain. In contrast, mining alters the very geology, topography, hydrology and ecology of sites within years or decades.
These earth-moving activities represent the kind of effect that has led many environmental scientists to argue that our planet has entered a new geologic epoch – the Anthropocene – where human choices have a greater impact on the earth than purely natural processes. Landscape evolution moves in very slow cycles, so these topographic and geologic impacts may last far longer than mining's effects on water quality. And because geologic processes are slow, scientists don't know how these landscapes will diverge or converge in their future evolution.
Essential and Scarce
Like oil and gas producers, mining companies have to contend with the fact that the products they seek are scarce, and easily extractable pools have already been tapped, leading to decreases in ore quality. But demand for these metals continues to grow.
Rapidly expanding green energy will require extracting vast quantities of rare earth metals to power wind turbines, electric vehicle batteries and solar panels. Cellphones, computers, camera lenses and other goods also contain these materials.
Economic imperatives lead companies to continue to push for new mines, either in the U.S. or abroad, where environmental controls may be weaker. And new projects are likely to move more rock, consume more energy and have longer-lasting impacts than those that preceded them.
Ensuring that mining operations are subject to effective oversight and long-term monitoring, and that companies are held accountable for environmental damages, is a long-term challenge wherever mining takes place. The best way to completely avoid the complications that come from mining more minerals is to reduce consumption of them, make mining processes more efficient and make it more economic to recycle industrial materials and rare earth metals.
Matthew Ross is an assistant professor of water quality at Colorado State University.
Disclosure statement: Matthew Ross receives funding from the National Science Foundation and NASA.
Reposted with permission from our media associate The Conversation.
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By D. André Green II
One of nature's epic events is underway: Monarch butterflies' fall migration. Departing from all across the United States and Canada, the butterflies travel up to 2,500 miles to cluster at the same locations in Mexico or along the Pacific Coast where their great-grandparents spent the previous winter.
Millions of People Care About Monarchs<p>I will never forget the sights and sounds the first time I visited monarchs' overwintering sites in Mexico. Our guide pointed in the distance to what looked like hanging branches covered with dead leaves. But then I saw the leaves flash orange every so often, revealing what were actually thousands of tightly packed butterflies. The monarchs made their most striking sounds in the Sun, when they burst from the trees in massive fluttering plumes or landed on the ground in the tussle of mating.</p><p>Decades of educational outreach by teachers, researchers and hobbyists has cultivated a generation of monarch admirers who want to help preserve this phenomenon. This global network has helped restore not only monarchs' summer breeding habitat by planting milkweed, but also general pollinator habitat by planting nectaring flowers across North America.</p><p>Scientists have calculated that restoring the monarch population to a stable level of about 120 million butterflies will require <a href="https://doi.org/10.1111/icad.12198" target="_blank">planting 1.6 billion new milkweed stems</a>. And they need them fast. This is too large a target to achieve through grassroots efforts alone. A <a href="https://www.fws.gov/savethemonarch/CCAA.html" target="_blank" rel="noopener noreferrer">new plan</a>, announced in the spring of 2020, is designed to help fill the gap.</p>
Pros and Cons of Regulation<p>The top-down strategy for saving monarchs gained energy in 2014, when the U.S. Fish and Wildlife Service <a href="https://www.fws.gov/southeast/pdf/petition/monarch.pdf" target="_blank">proposed</a> listing them as threatened under the Endangered Species Act. A decision is expected in December 2020.</p><p>Listing a species as endangered or threatened <a href="https://www.fws.gov/endangered/esa-library/pdf/listing.pdf" target="_blank">triggers restrictions</a> on "taking" (hunting, collecting or killing), transporting or selling it, and on activities that negatively affect its habitat. Listing monarchs would impose restrictions on landowners in areas where monarchs are found, over vast swaths of land in the U.S.</p><p>In my opinion, this is not a reason to avoid a listing. However, a "threatened" listing might inadvertently threaten one of the best conservation tools that we have: public education.</p><p>It would severely restrict common practices, such as rearing monarchs in classrooms and back yards, as well as scientific research. Anyone who wants to take monarchs and milkweed for these purposes would have to apply for special permits. But these efforts have had a multigenerational educational impact, and they should be protected. Few public campaigns have been more successful at raising awareness of conservation issues.</p>
<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="91165203d4ec0efc30e4632a00fdf57d"><iframe lazy-loadable="true" src="https://www.youtube.com/embed/KilPRvjbMrA?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
The Rescue Attempt<p>To preempt the need for this kind of regulation, the U.S. Fish and Wildlife Service approved a <a href="https://www.fws.gov/savethemonarch/pdfs/Monarch%20CCAA-CCA%20Public%20Comment%20Documents/Monarch-Nationwide_CCAA-CCA_Draft.pdf" target="_blank">Nationwide Candidate Conservation Agreement for Monarch Butterflies</a>. Under this plan, "rights-of-way" landowners – energy and transportation companies and private owners – commit to restoring and creating millions of acres of pollinator habitat that have been decimated by land development and herbicide use in the past half-century.</p><p>The agreement was spearheaded by the <a href="http://rightofway.erc.uic.edu/" target="_blank">Rights-of-Way Habitat Working Group</a>, a collaboration between the University of Illinois Chicago's <a href="https://erc.uic.edu/" target="_blank" rel="noopener noreferrer">Energy Resources Center</a>, the Fish and Wildlife Service and over 40 organizations from the energy and transportation sectors. These sectors control "rights-of-way" corridors such as lands near power lines, oil pipelines, railroad tracks and interstates, all valuable to monarch habitat restoration.</p><p>Under the plan, partners voluntarily agree to commit a percentage of their land to host protected monarch habitat. In exchange, general operations on their land that might directly harm monarchs or destroy milkweed will not be subject to the enhanced regulation of the Endangered Species Act – protection that would last for 25 years if monarchs are listed as threatened. The agreement is expected to create up to 2.3 million acres of new protected habitat, which ideally would avoid the need for a "threatened" listing.</p>
A Model for Collaboration<p>This agreement could be one of the few specific interventions that is big enough to allow researchers to quantify its impact on the size of the monarch population. Even if the agreement produces only 20% of its 2.3 million acre goal, this would still yield nearly half a million acres of new protected habitat. This would provide a powerful test of the role of declining breeding and nectaring habitat compared to other challenges to monarchs, such as climate change or pollution.</p><p>Scientists hope that data from this agreement will be made publicly available, like projects in the <a href="https://www.fws.gov/savethemonarch/MCD.html" target="_blank">Monarch Conservation Database</a>, which has tracked smaller on-the-ground conservation efforts since 2014. With this information we can continue to develop powerful new models with better accuracy for determining how different habitat factors, such as the number of milkweed stems or nectaring flowers on a landscape scale, affect the monarch population.</p><p>North America's monarch butterfly migration is one of the most awe-inspiring feats in the natural world. If this rescue plan succeeds, it could become a model for bridging different interests to achieve a common conservation goal.</p>
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