The world’s largest and perhaps most destructivemining industryis rarely discussed. Approximately85 percentof all material mined from the earth is a simple and widely available resource: sand. Because it is so cheap and readily available, it is mined by everyone from guy with a shovel, to multi-million dollar machine operations. The majority ofsandis used to make concrete, but the displacement of sand leads to the catastrophic destruction of coastal, sea bed and river ecosystems and topography.
联合国环境规划署估计that 40 billion tons of sand are mined every year, but since the market is corrupt, hidden and decentralized there have been no comprehensive studies to date. In order to get a rough number, the United Nation’s used globalcementproduction and sales figures to approximate how much sand is collected. For example, every ton of cement requires six to seven tons of sand and gravel in order to make concrete.
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The environmental impact
Sand mining, especially when done without regulation or oversight, can damage rivers, cause beach erosion and destroycoastal ecosystems. At least 24 Indonesian islands disappeared off the map just to build Singapore.
Since sand dredging occurs primarily for construction purposes, miners target river and coastalecosystemswhere the sand is ideal. River sand is particularly perfect for concrete because it is coarse and does not contain salt that would otherwise corrode metal and other building materials. In addition to disturbing riverbed and river bank ecosystems, altering the flow and capacity of rivers can cause drought or disastrous flooding– though rarely recognized as a contributing factor.
In Kerala, India, flooding was found to be partially caused by sand dredging that took 40 times more sand out of the river bed than the river could naturally replace.
Dredging sea grass habitat can also cause sediment to drift for miles causing both coastal erosion and smothering ecosystems likecoral reefs. Erosion, land subsidence and the introduction of heavy machinery and vehicles into delicate habitats also threatens the integrity of nearby infrastructure such as roads and bridges.
Onestudyfound that every ton of sand taken from a river in California cost taxpayers $3 in infrastructure damage.
城市对砂的需求
Developmentand urbanization are expanding rapidly in every corner of the world to accommodate an exponentially growing population and our insatiable rates of consumption and expansion. According to the United Nations, the number of people living in cities is more than four times what it was in the 1950s. Over 50 percent of the world’s population now lives in urban areas with nearly three billion additional people expected to migrate to cities in the next 30 years.
In addition to new buildings, sand is also used for land expansion projects. InChina, it is a common practice to dump sand on top of coral reefs to speed the process of building land. Dubai is also famous for its man-made islands, which required millions of tons of sand.
Singapore has added over 50 square miles of land in the past four decades and more skyscrapers in the last 10 years than all of New York City— a feat that required over 500 million tons of sand. The creation of Singapore was so rapid that Indonesia, Malaysia and Vietnam all banned the export of sand, but miners simply moved to Lake Poyang on the Yangtze River. The WWF calls this Lake thelargest sand minein the world, but it is tragically also Asia’s largest destination for migratorybirds. Sand dredging activities have more than doubled the river’s capacity in certain areas, draining parts of the lake and reducing key fisheries.
“It’s the same story as over-fishing and over-foresting,”says Pascal Peduzzi,from the United Nations Environment Program. “It’s another way to look at unsustainabledevelopment.”
The scale of the problem is enormous and the consequences of moving massive amounts of life-and land-sustaining material from one place to another is glaring but the world remains functionally oblivious, blinded by the desire for new buildings and up-and-coming neighborhoods.
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Can sand dredging be done sustainably?
Riverecologistssuggest that sand dredging in rivers should only be done up to a pre-determined quota that allows the river to annually replenish sediment. However, this sustainable number will never equal humanity’s unsustainable need for development.
There are a number of suggestions to improve the sustainability of the industry, but none are perfect:
Offshore sand mining
Britain now sources much of its sand further offshore in order to protect river and coastal ecosystems, however, much of this sand is only used for land reclamation projects where the salt content is not a concern.
Sandy bottom reservoirs
Another untapped source is the sand that collects at the bottom of reservoirs. Dredging reservoirs could not only provide sand but also helps to expand storage capacity. Ecologists, however, argue that this sand should technically be put back into theriversthat feed into reservoirs.
Recycling glass and rubble
Rubble from demolished buildings can be used to produce concrete, reducing the need for fresh sand. Glass can also berecycled, which again reduces the need for sand.
矿业在洪plains
Limited mining on floodplains, rather than riverbanks and riverbeds, is thought to be less destructive. However, floodplains also have fragile ecosystems. In Australia, floodplains are home to rare carnivorous plantspeciesthat are now at risk from mining activities.
Replacing sand in concrete
Ash from incinerators and dust from stone quarries can be used in the production of concrete to reduce the demand for sand.
Images via Shutterstock
