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Oil spills are one of the most common catastrophes in nature. They endanger the environment? animals and plants alike. Many solutions are available to clean up petroleum disasters, but most them all hurt wildlife as well. Phytoremediation is a natural, effective way to clean up sludge or oil spills on land. What plant works best for phytoremediation and what makes them work better than the other plants?Katherine Banks and Paul Schwab, both professors at Purdue University, were the first to test out the process of phytoremediation, which means using plants to clean up polluted soil. The research team had already used this process to clean up a Texas oil pipeline spill, an Indiana gas plant, a sludge site in California, and diesel spills in Virginia and California. Their work is compiled in the book “Bioremediation of Contaminated Soils”, which was published by the American Society of Agronomy. The way phytoremediation actually occurs is through microbes in the soil that break down petroleum pollutants. Plants only speed up the microbes’ work by allowing more oxygen to penetrate the soil and by stimulating microbes to degrade contaminants. They also supply nutrients to the soil, doing all of this through their roots. That’s why plants with larger root surfaces work better for phytoremediation, like fescue, Bermuda grass, clovers, and alfalfa (Banks, 2000). Using plants to clean up oil spills has its pros and cons. It costs less than other ways of purifications and doesn’t disturb the soil structure. Other standard methods require movement of soil and then either composting, landfilling, or incinerating the foreign substances.  One study with the EPA and Indiana Gas Co. is comparing efficiency of several methods at a coal-to-natural gas refinery over several years. This has become a demonstration project for natural gas manufacturers nationwide (Schwab, 2000). Schwab and Banks methods are quickly being adopted all over the world. They are continuing to focus on cleaning up petroleum products as petroleum is one of the major soil pollutants around the world. While plants aren’t the fastest means to clean spills, they are the most natural method and the best way to leave the environment undisturbed.                       The process of refining oil can create high levels of contaminated soil, or ‘sludge’. Sludge is different than oil spills as while spills are a one time event, sludge is produced all the time in oil refineries. That’s why Lithuanian company Biocentras and partners from Latvia and Lithuania thought to develop a solution. They created a much needed technique that has so far cleaned 22,000 tons of soil without using dangerous chemicals. This natural, three step process changes polluted soil so it can be used again for growing all kinds of plants. For the soil to be properly cleaned, it can either be treated on site or removed before being treated if the area can be easily unbalanced. It is then washed with a water solution of biosurfactant up to ten times, and then separated. Biosurfactants are compounds that contain both nonpolar molecules that repel water molecules and molecules that form ionic or hydrogen bonds with water. These moieties reduce surface tension and interfacial tension between individual molecules. Because of this, surfactants go to work reducing the hold of the oil and water. With the oil film’s bond lessened, the water can break up the slick into small drops of oil. The small drops then sink down and can be separated from the water (Pacwa-P?ociniczak, 2011). Some oil is cleaned off with the biodegradable biosurfactant solution, but some may remain. This is where the third step comes into play. The oil is treated with micro-organisms that bring the concentration of impurities down. Then phytoremediation can start, which is the use of plants to clean up polluted soil. Many existing solutions for contamination rely solely on dangerous chemicals. Potential side effects on the environment are high and more natural processes are desired, especially with the reality of how humans affect the environment. That is why this process works best, as it is all natural and very effective in treating the contamination.      Scientists like William Graves, associate dean of the ISU Graduate College and professor of horticulture, and James Schrader, an associate scientist in horticulture, are interested in the effects of petroleum based plastics on plants. They and a team of researchers conducted a five-year study on bioplastics funded by the U.S. Department of Agriculture’s National Institute for Food and Agriculture to try to find materials that may yield promise in replacing regular plastic. Bioplastic containers, made from renewable sources such as polylactic acid, polyhydroxyalkanoates, corn, soybeans, and ethanol seem the best fit. These containers have the potential to offer major advantages that petroleum products cannot. These include biodegradability, easing dependence on fossil fuels, and the ability to self-fertilize plants. Plastics from bio-based materials release nutrients as they decay. This could lessen work gardeners must do and also encourages plant growth (improves plants ability to thrive after transitions). The study also concluded that pots made from these plastics cost between two and 11 cents more per unit to manufacture than pots made from conventional petroleum material. But gardeners may be willing to pay a little extra for products that help the environment. According to Schrader, the market for bioplastics will start small, then eventually evolve as the niche market expands over time (Graves, 2017).Petroleum releases an odor that is special to its toxic make up. If you put this fossil fuel in a Petri dish with mushrooms, somehow the smell disappears. Mohamed Hijri, who is a professor and researcher at the University of Montreal’s Institut de recherche en biologie végétale (IRBV), is leading a project with B. Franz. They are observing bacteria to further the growth of specific plants and microscopic mushrooms. Their project starts off by planting willow cuttings with degrading contaminants as well as bacteria in the soil. After the willows have done their job, they burn them. The residue is a few ashes that contain all the heavy metals collected in the plants. It only takes a few cycles to clean the densely polluted soil. The researchers also collected microorganisms that decompose fossil fuels. They believe that separating species that are most efficient, they can speed the process of phytoremediation. The project, Improving Bioremediation of Polluted Soils Through Environmental Genetics, is a thorough project with 16 researchers, fieldwork, sampling, and DNA sequencing of the plants (Hijri, 2011). Other researchers, like Villa of the University of Eastern Finland seem to agree that willow trees are inexpensive and efficient way to purify soil. They can grow in acidic and metal laden soil, which is great for phytoremediation. Many plants cannot even survive in contaminated soil. Some willow tree species are even more efficient than others. Salix schwerinii proved to be the best survivor, while a hybrid willow species was able to produce more wood ash than the others (ash and side products from the trees lowers the acidity of the soil) (Villa, 2014). Phytoremediation in the future will try to improve the speed and efficiency of plants to clean contaminated sites, through genetic engineering or breeding. Some of the ways to improve may be root depth, root spread, and accumulation. More companies are investing in phytoremediation research as interest grows in this easy, practical, and environmentally friendly approach to the remediation of poisoned soil.

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