The BEST program also sponsored a phytoremediation workshop for BEST investigators and students that was attended by more than 60 participants. Additional workshops are planned for the coming year. In this report, the research is organized by subject area, and two-page briefs are presented for each of 28 BEST projects. The projects presented provide a good representation of the state-of-the-science research being done with students in the BEST program – the best of BEST.Over the next 75 years, the U.S. government will undertake what has been called the largest civil works project in world history to restore the environment damaged by previous activities at federal sites, e.g., Department of Defense military bases and Department of Energy nuclear facilities. Legislative action, resulting from concern over the accumulating hazards, has mandated pollution control measures and environmental restoration of hazardous waste at all sites. Estimates of total cleanup costs range from $230 billion to more than half a trillion dollars. Given the trend of diminishing budgets throughout the federal government,vertical home farming future generations could inherit both an environmental and budgetary disaster. The imprecision of the cost estimates results from the lack of knowledge of how “clean” the contaminated sites will need to be. Some of the environmental damage is permanent—cleanup technologies either do not exist or are incapable of remediating the contamination.
For DoD bases being closed by the Base Realignment and Closure Program, all toxic sites must be remediated before the site is returned to public use. The projected costs of site restoration using existing technologies are staggering: the estimated cleanup cost is at least $24.5 billion for the 7,313 identified U.S. sites . The pollutants at these sites include chlorinated hydrocarbons, metals, petroleum products, explosives, mixed waste and other organics. DOE also has substantial remediation costs—estimated to be from $90 billion to $200 billion . The domestic private sector presents yet another huge set of remediation problems, dwarfed only by the international problems in Eastern Europe and Russia . There is clearly a need for new cost-effective treatment technologies. Bio-remediation, the use of microorganisms to detoxify hazardous waste, promises to provide economical and ecologically sound clean-up strategies. An Office of Technology Assessment analysis concluded that the U.S. does not possess a sufficient pool of qualified environmental professionals, i.e., the trained scientific personnel required to support this rapidly developing multidisciplinary field. In response to these national environmental needs, the Bio-remediation Education, Science and Technology Program, funded by DoD, was established in 1996. In a few short years, BEST has pioneered a new and successful model for environmental science and education. This partnership has a highly integrated programmatic focus on the scientific and workforce needs of DoD. Since the inception of the BEST program, a significant number of major milestones and deliverables have been achieved. They are described below. The BEST program has made these dramatic accomplishments by using an approach that combines a training-education element with an integrated research project, described later in this introduction.
Successful restoration of DoD hazardous waste sites and the growth of the bio-remediation industry is dependent on a cadre of trained scientists, engineers and technicians. By the year 2005, thousands of trained professionals will be required to meet DoD and national environmental needs. The BEST partnership continues to build upon accomplishments and successful programs developed with DoD support. The training-educational element continues to provide career development opportunities for underrepresented groups with bio-remediation curricula, courses and fellowships. The training-educational experience is personalized to provide students with a meaningful bio-remediation curriculum, financial support, an extensive mentorship network, and research and field training. The shared resources of the BEST partnership institutions aid faculty in the development of curricula, courses and environmental research projects. The training-education programs span the continuum from community college outreach to faculty development, but focuses on undergraduate and graduate students. Innovative features of the BEST program are the use of distributed learning technologies and a Rotating Scholar Program, integrated with a coordinated academic and video seminar curriculum.The primary objective of the BEST program is to provide hands-on training in bio-remediation, phytoremediation and ecotox/risk assessment for underrepresented minorities. Students will obtain the necessary skills and knowledge to enable them to either enter the environmental science workforce with a bachelor’s degree or enter graduate school at the master’s or doctoral level. Another objective is to ensure a continued supply of skilled workers to address the diverse environmental restoration needs at DoD sites.
DoD sites throughout the United States contain highly contaminated soils, groundwater and sediments. These properties pose direct and indirect exposure hazards to humans and wildlife. Conventional remedial solutions for contaminated soils and sediments or groundwater are slow and expensive, increase inputs to hazardous waste disposal sites, and can increase human exposure to contaminants. Bio-remediation — the use of microo ganisms to destroy hazardous contaminants or to convert them to harmless forms — is an emerging treatment technology that can in many instances restore contaminated environments more quickly, at lower cost and at lower human risk than alternative remediation technologies. Bio-remediation can operate in either an in situ mode where contaminants are treated in place, or in an ex situ mode where contaminants are removed from a contaminated zone for treatment . In situ bio-remediation can be used when excavation is impractical — under buildings, highways, runways, etc. In situ bio-remediation can simultaneously treat soil and groundwater in one step, without the generation of hazardous waste products. In situ contaminant degradation can be achieved by either intrinsic or enhanced bio-remediation. Intrinsic bio-remediation exploits the innate capabilities of indigenous microbial communities to degrade pollutants. Enhanced bio-remediation seeks to accelerate in situ microbial activity by isolating and controlling the contaminated site so that the microbial environment can be purposely manipulated to correct nutritional or gas phase limitations. Ex situ treatment seeks to further control the remedial environment by placing the contaminants in an engineered treatment system. Phytoremediation, a process in which plants and associated microbial communities are used for contaminant biodegradation or bioimmobilization, is an important and rapidly developing mode of bio-remediation. To realize the full potential benefits of plant and microbial treatment systems at DoD sites, these bio-technologies must be developed and optimized for remediation of DoD priority contaminants by an expanded pool of qualified professionals. It was in response to these DoD environmental needs that the BEST partnership of institutions was established.
In order to determine whether plants can stimulate the degradation of PAHs in soil, plant species found in literature on phytoremediation of metal-contaminated sites were selected to measure the removal of PAHs in artificially contaminated soil over a period of 62 days. The plant species used for this experiment were alfalfa , barley , tall fescue and orchard grass . The PAHs were phenanthrene and anthracene, in a mixture of 600 ppm each. As shown in Figures 1 and 2,vertical growers phenanthrene and anthracene were removed from the soils with plants after 62 days. More than 98% of the phenanthrene was removed during that period while the anthracene removal was found to be between 70 and 90%. The results suggest that the rate of disappearance of phenanthrene in soil was greater than anthracene under the same conditions. From the results, it is also indicated that the disappearance of PAHs in soil depends on the bio-availability of the compounds. Because phenanthrene is approximately 10 times more soluble in water than anthracene, it was expected to be more readily available to microbial degradation than anthracene. Plant-assisted degradation of PAHs is thought to be more effective on PAHs with a higher number of rings and higher molecular weights, such as benzopyrene. Anthracene removal in the soil planted with alfalfa was greater than in the soil without plants, while all the other plants have minimal to no effect on anthracene removal compared to the control soil. Phenanthrene was removed to a greater extent in the soil with alfalfa and tall fescue compared to the control without plants . However, both barley and orchard grass showed no effects of the removal of phenanthrene during that period when compared to the soil without plants. Overall, plants had minimum effect on phenanthrene degradation while anthracene degradation was more dependent on plant species. In order to determine the effect of PAH degradation by plants on bacterial numbers in soil, bacteria were counted in soil during the course of the experiment.The result suggests that the degradation of PAHs by plants is not affected by differences in bacterial biomass in the soil. Sterile controls will be used in the future in order to assess the role of bacteria in the degradation process.Wheat is a crop of major importance and together with other staple cereals supply the bulk of calories and nutrients in the diets of a large proportion of the world population . Cereals are inherently low in protein and mineral micro-nutrients such as Fe and Zn . A major focus of wheat breeders has been grain protein concentration as it affects bread- and pasta-making quality, but micro-nutrient improvement has received less attention. Approximately half of the world’s population suffers from Fe and/or Zn deficiencies and millions of children suffer from protein-energy malnutrition . As such, the improvement of nutritional quality of wheat could benefit the nutritional status of millions of people. A common agronomic practice to increase grain protein concentration is the use of N fertilization. However, this practice is expensive and excess fertilizer run-off is a potential environmental contaminant . A substantial percentage of the N in wheat grain is supplied by amino acids remobilized from vegetative tissue .
Much of this N content is derived from proteins that are disassembled and recycled during the leaf senescence stage of development . Likewise, Fe and Zn have been shown to be remobilized from vegetative tissues in several plants , although the specific sources are unknown. Zinc fertilization has been a successful strategy to improve wheat grain Zn concentration , and improvement in the partitioning or remobilization of Zn to grain could make fertilization efforts more efficient. Wheat grain with higher Zn concentration has been demonstrated to produce more vigorous crops . Thus, breeding or transgenic approaches that result in plants with increased partitioning of minerals to grain could be useful for both nutritional bio-fortification and reduced fertilizer application. Chromosome 6B from wild emmer wheat was identified as a potential source of genetic variation for grain protein , Zn, and Fe concentration . A quantitative trait locus for grain protein concentration was mapped on chromosome arm 6BS and later mapped as a single Mendelian locus, Gpc-B1 . In near-isogenic lines of this locus, increased grain protein was associated with the increased remobilization of amino acids from the flag leaf , higher grain Fe and Zn concentrations , and accelerated leaf yellowing, indicating accelerated senescence . A NAC transcription factor, NAM-B1, was identified as the causal gene for Gpc-B1 by positional cloning . Other members of the NAC family are known to regulate developmental processes , including leaf senescence . In transgenic wheat NAM RNA interference lines in which NAM-B1 and its homeologous genes had decreased expression, leaf yellowing was delayed, and grain protein, Fe, and Zn concentrations were greatly decreased . These results, together with higher N, Fe, and Zn concentrations in RNAi line flag leaves at maturity, suggested a role for NAM-B1 homeologues in the remobilization of N compounds, Fe, and Zn. However, without taking organ mass, nutrient concentrations at prior time points, and total nutrient accumulation of other organs into account, this model could not be confirmed. In addition, the body of literature does not contain sufficient data regarding sources of grain minerals to support the idea that remobilization alone could account for the differences observed. Because a whole-plant partitioning profile has not been undertaken in plants differing in NAM-B1 expression, it is currently unclear whether this gene directly affects remobilization , alters partitioning of nutrients within the plant, alters total plant uptake of these nutrients, or influences a combination of these processes. The current study uses multiple time point sampling of an expanded profile of mineral concentrations and contents of all shoot organs in NAM knockdown and control lines. This sampling allows the quantification of N and mineral remobilization as contributors to final grain protein and mineral content, and provides a better understanding of the physiological effects of the NAM genes.