Soil pollution is the real culprit threatening plant growth

Text: Chen Jen-chen / Wutong Environmental Integration Foundation
Image source: http://goo.gl/NVpjQR

Nuclear waste, the energy crisis, contaminated land and water resources, and high concentrations of greenhouse gases are the major problems facing the environment today, but do you believe that plants can solve all of these problems? They can not only remove nuclear waste, solve the energy crisis, and purify contaminated land and water, but also reduce the negative effects of greenhouse gases. "Phytoremediation" uses the ability of plant roots to absorb water and nutrients, offering a new direction for pollution treatment.

In the past, the approach to dealing with soil contamination was to dig up all the contaminated soil and then bury it deeper underground, far from the surface and ordinary water sources. But the trouble is that pollutants easily seep through every gap in the soil along with the flow of water, and so the soil that needs to be dug up and treated is often several thousand tons or tens of thousands of tons. Heavy metal pollutants in particular bind with the clay and organic matter in the soil, making the purification process especially time-consuming and energy-intensive. Where does the excavated soil get buried? Usually in sparsely populated, remote wilderness areas, or near some village or island. This contaminated land often still cannot grow crops even after decades, leaving behind a wasteland that neither people nor animals can use.

"Phytoremediation" removes, breaks down, or immobilizes pollutants from the soil by planting highly tolerant tree species. The U.S. Environmental Protection Agency (EPA) has compiled nine different phytoremediation techniques, each applying the physical and physiological characteristics of plants to deal with different contamination situations. Some techniques specifically target organic pollutants produced in daily life, such as insecticides, pesticides, and detergents, and then combine with soil microorganisms to speed up the breakdown of these organic substances. Other techniques specifically target heavy metals and nuclear waste, relying on plant roots to absorb them into the plant body, after which the plants are removed. Compared with traditional techniques that must handle large amounts of soil, phytoremediation only needs to handle individual plants that have already encapsulated the pollutants within themselves, which is not only more efficient but also safer.

Of course, if purifying land were possible by this alone, the earth might already be free of pollution problems. In reality, phytoremediation still faces many problems, such as the slow growth rate of trees, which makes it impossible to solve problems quickly; moreover, pollutants underground that tree roots cannot reach cannot be removed. Technically, some techniques still in the experimental stage may even release toxic substances, and plants that can tolerate severe contamination have still not been found. Because heavy metals, nuclear waste, and the like cannot be broken down, plants can only store them within their bodies at the cost of sacrificing themselves, after which they are sent to waste treatment plants for isolation or recovery.

Although phytoremediation has already begun to be applied abroad, and its future still seems to hold much room for development, do you agree that changing our lifestyle, conserving energy and electricity in daily life (eliminating the motive to build nuclear power plants), and using fewer chemical products to avoid pollution are the most fundamental solutions?

Source: http://chicagohumanities.org/blog/interns/alissa-zhu-using-trees-to-clean-up-pollution