Introduction:
Photoextraction uses plants to remove heavy metals and other contaminants from the soil. This can be a “two edged sword.” When animals consume them, can cause high concentration of contaminants on higher levels on up the food chain. Fortunately, they also present the potential for use as biomass in alternative fuel production. . Some species of plants are more effective as Photoextractants than others are. Other plant species are more effective when used as biomass. Ideally, plants used for Photoextraction should be capable of absorbing a spectrum of contaminants, and provide cost effective biomass. Testing is needed to determine if there are any plants that are effective in both capacities.
Thesis:
Plants from the Brassica Family used for Photoextraction are useful for biomass in alternative fuel production.
Subthesis A:
Plants from the Brassica Family are useful for Photoextraction.
Subthesis B:
Plants from the Brassica Family used for Photoextraction useful as biomass for alternative fuel production.
Hypothesis:
Some plants from the Brassica Family are useful for both phytoremediation and for biomass production.
Procedure:
This proposal employs a two phase process to answer both elements of the thesis. The initial phase of this research requires testing plants in the Brassica Family to determine plants that operate as Photoextractants. The next phase will utilize the plants as biomass for alternative fuel production.
For research efficacy, should address both phases of the thesis using the same plants. For the first phase, several species of Brassicas should be tested in the same contaminated soil blend. A control group consistent with the same parameters should also be grown in uncontaminated soil. For the second phase both the contaminated plant and the control plants should be tested to determine if they can be used for biomass in alternative fuel production.
Independent Variables:
In the first phase, the same base soil used for both the test group and the control group. A spectrum of heavy metal contaminants will then be added to the plants in the test group. By employing this method all test plants will be offered the same spectrum of contaminants. All the plants, including the control group will receive the same soil nutrient balance. To avoid inadvertent variables, distilled water will be given to both the test and control group. One potential problem could arise if some plants require more water than others do. Therefore, all water use will be monitored and recorded.
In the second phase, the plants themselves will serve as the independent variables. Each plant species will be subjected to the same process for use as biomass production.
Dependent Variables:
In the first phase, both leaf samples from the plants and soil samples will be tested for contaminants. At the conclusion of the first phase, soil samples, along with plant root, stem, leaf and seed samples will be tested. This is an important consideration as previous studies have shown that different parts of plants proved that different portions of the same plant indicate that within one plant different portions of the same plant absorbed contaminants differently. In a study conducted using Brassica chinensis L.( pakchoi):
86.7 and 76.3% of the Pb that accumulated in the roots and shoots, respectively, was contained in the cell wall and vacuoles in those areas. Whereas 75.0% of the Cr that accumulated in the root was contained in the cell wall, 63.1% of the Cr that accumulated in the shoot was found in the vacuoles and cell wall..
This study shows that soil cleansed by the Phytoremediation process will benefit if the plant are dug up as part of the harvesting process rather than harvested at the stem level. This is an important consideration as one harvesting may be more cost effective in the short term if the plants were just used as biomass. However, since the intent is that plants serve a duel function as both Photoextractants and biomass the entire process might be more effective if the plants are harvested and used root stem, leaf and seed.
Controlled Variables:
The only variable in the second phase is the different plants from the first phase of the project. At the end of the second phase each plant will be evaluated separately regarding how productive it is as a source of biomass.
Conclusion:
It is expected that there will be some members of the Brassica Family of plants that are effective as Photoextractants and as biomass.
Areas for Future Study:
Some Brassicas are useful for both biomass and oil production. The rapeseeds used to produce canola oil are an example of this. There for these plants may serve a duel function, producing both biomass and oil.
Works Cited
Kumar, P B.A, et al. "Photoextracion: The Use of Plant To Remove Heavy Metals from Soils." 05 1995. Environmental Science & Technology. <http://pubs.acs.org/doi/abs/10.1021/es00005a014>.
Salanitro, Jospeph P, et al. "Cride Oil Hydrocarbon Bioremediation and oil Ecotoxicity Assessment." 05 1997. Environmental Science & Technology. <http://pubs.acs.org/doi/abs/10.1021/es960793i>.
Wu, Zhipeng, et al. "Subcellular Distribution of Metals within Brassica chinensis L. in Response to Elevated Lead and Chromium Stress." 26 04 2013. ACS Publications. <http://pubs.acs.org/doi/abs/10.1021/jf4005725>.
