Tomorrow, Kaitlyn Frederick and Yenner Ulus, graduate students under Dr. Johnston's tutelage, will be presenting their work during seminar. Both of these presentations will be the basis of their thesis proposal defenses. Be sure to attend and provide them some positive, constructive criticism.
Whose turn to come up with the discussion question?
Hi guys,
ReplyDeleteLast week I presented my thesis work on phytoremediation on heavy metals in suburban lead contaminated soil. I talked about; main sources of contaminants (Organic compound and heavy metals), how they affect human health, environment cleaning technologies (particularly on phytoremediation), and chelators. Basically, I used two different plants (Indian mustard and sunflower) in order to remediate soil which was contaminated by lead based paint. I also used chelator (Ethylenediamine-N,N'-disuccinic acid, EDDS) to make metals available for plant uptake.
There was no enough time for me to get into details for phytoremediation types. Therefore, my question is what are the phytoremediation types? (You can pick one of the phytoremediation types and explain it).
Thanks,
Phytoremediation describes the treatment of environmental problems (bioremediation) through the use of biological agents to remove, neutralize or detoxify contaminants in the environment. This mitigates the environmental problem without the need to excavate the contaminating material to dispose of it elsewhere.
ReplyDeletePlants can help clean up many kinds of pollution material including metals, pesticides, explosives and oil. Besides, plants can also help prevent wind, rain, and groundwater from carrying pollution away from the original pollution sites to other locations. Plants work best at sites with low to medium amounts of pollution. The harmful chemicals are removed by plants as they take up water and nutrient from polluted soil, stream and ground water, via their roots. Once inside the plant, chemicals can be stored in the roots, stems, or leaves or changed into less toxic chemicals or gas which is released to the air through transpiration.
Not every plant species are good in phytoremediation. some plants have greater capacity to take up more metals than normal plants and these are called hyperaccumulators. Hyperaccumulators can absorb more heavy metals than is present in the soil in which they are growing .However all plants need some heavy metals in small amount for example iron, copper, and manganese which are essential to plant function and so to an extent they all may serve as phytoremediater.
Rhizodegradation, also known as plant-assisted bioreme-diation/degradation, is a process that breaks down contaminants in the soil surrounding the roots of the plant. Microbes living near the roots, break down the contaminants and use them for their own metabolic purposes. After, the microbes release non-harmful products back into the soil to be used by other organisms. The plant is able to contribute to this breakdown by offering by-products of its own metabolic processes to act as a nutrient source for the microbes. The plants also loosen the soil and allow water to reach microbes. This allows for a safe breakdown of hazardous contaminants and allows a symbiotic relationship to form between the plant and local microbes. However, this is a slower process compared to other phytoremediations.
ReplyDeleteGood job presenting Friday, Yenner! Pretty interesting stuff. An additional type of phytoremediation is phytovolatilization. This process involves the uptake of contaminants through the roots of plants, where they are released by into the atmosphere in an evaporative or vaporized state. As growing plants absorb water and organic compounds, so do they also contaminants. Plants with high evapotranspiration rates are sought after for this process. An example of a plant used for this process includes poplar trees, where one study showed up to 90% removal/dispersal of TCE (trichloroethylene) absorbed. This process is primarily used to remove mercury, where it is converted into less toxic elemental mercury and has been mainly applied to ground water. It can also, however, be applied to soil, sediments, and sludges.
ReplyDeletehttp://conservancy.umn.edu/bitstream/handle/11299/59470/5.4.Lay.pdf?sequence=1
Phytotransformation is the ability of a plant to change the chemical structure of a pollutant in order to make it less harmful. Phytotransformation occurs in 3 phases. In Phase I metabolism, plants use enzymes to increase the polarity of foreign compounds or pollutants by adding functional groups like hydroxyl groups. Plants use enzymes like peroxidases, phenoloxidases, esterases, and nitroreductases to do this. This is b similar to the way that the human liver increases the polarity of drugs by cytochrome P450s. In Phase II, plant molecules, like glucose and amino acids, are added to the polarized foreign compound to further increase their polarity and reduce their toxicity. This increase in polarity allows for easy transport of compounds through aqueous channels. Phase III concludes the process with the sequestering of the foreign material to make sure that it is safely stored and does not harm the plant. Consuming the plant may still be harmful to some organisms.
ReplyDeletePhytoremediation is a very environmentally friendly at removing pollutants in the soil. It costs less than traditional methods for removing such contaminants and in the case of heavy metals, they can be recovered from the plants and recycled, which is called phyto mining. However, a few drawbacks to phytoremediation is that it takes a considerably long time for the plants to clean the soil compared to traditional methods and these pollutants may find their way into the food chain as animals may eat the phytoremediation plants. Going back to Dr. Carson's lecture, it appears that plants species used for bioremediation should be browser tolerant to prevent the pollutants from entering the food chain. Sunflowers are very effective at phytoremediation and were used to remove Cesium-137 and Strontium-90 from a pond following the Chernobyl Nuclear disaster, but sunflowers are used as a food source for lepidoptera larvae, which would risk contaminating the food chain. For the past 2 decades the Bureau of land management has been using plants for phytostablization at abandoned mines to reclaim the land. Phytostabilization prevents the migration of heavy metals in the soil and reduces soil toxicity.
ReplyDeleteYener, you did a great job presenting.
ReplyDeleteThere are five types of phytoremediation: phytoextraction, phytostabilization, rhizofiltration, phytovolatilization, and phytotransformation.
Phytoextraction is the uptake and translocation of metals from soil to the top tissues of the plant.
Phytostabilization is the reduction of mobility, restriction of metals in root tissue and precipitation in the root zone.
Rhizofiltration is the removal by absorption and precipitation on the surfaces or radical absorption in the roots.
Phytovolatilization is the absorption and release to the atmosphere of volatile materials.
Phytotransformation is the decomposition of contaminant by metabolism or plant enzymes.
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Phytostabalization is when plants are used to decrease the erosion of the toxins. This stabilization prevents spreading of the toxins however doesn’t get rid of them. In this process the plant itself prevents the water erosion. When the plants are planted in these areas of pollution their presence actually prevents pollutants from being carried to other areas. The benefits of this process are things such as less likely for livestock and human exposure to these toxins however this process doesn’t rid the toxins so they are still present in theses areas which may result in these areas being permanently polluted. An example of this technique is used when vegetable caps are planted and contain mine tailings.
ReplyDeletePhytoremediation is an emerging technique that uses plants to clean up pollutants(heavy metals) from the environment. Phytoextraction is a sub field of phytoremediation that involves the utilisation of plants to transport and concentrate metals from the soil into the harvestable parts of roots and above-ground shoots. Other traditional remedial methods have not been as effective and are extremely costly. Phytoextraction is a much more cost effective approach, harvestable parts can be extracted and disposed of either through drying, burning or composting. Heavy metals can be extracted from Ashes and recycled, generating revenue, making the method more effective. Phytoextraction is being used commercialy by any companies and phytoremediation is a futuristic technique that will clean up our heavily polluted environment from industries, cars, nuclear stations etc.
ReplyDeletehttp://www.ncbi.nlm.nih.gov/pubmed/11272009
Rhizofiltration (rhizo- means root) is the adsorption or precipitation onto plant roots or absorption into the roots of contaminants that are in solution surrounding the root zone. Rhizofiltration is similar to phytoextraction, but the plants are used primarily to address contaminated ground water rather than soil. The plants to be used for cleanup are raised in greenhouses with their roots in water rather than in soil. To acclimate the plants once a large root system has been developed, contaminated water is collected from a waste site and brought to the plants where it is substituted for their water source. The plants are then planted in the contaminated area where the roots take up the water and the contaminants along with it. As the roots become saturated with contaminants, they are harvested. For example, sunflowers were used successfully to remove radioactive contaminants from pond water in a test at Chernobyl, Ukraine.
ReplyDeletehttp://www.oocities.org/mikiang2/mich3.htm