pollution, and the ice plant would be an edible saleable crop. In addition to NaCl remediation of hydroponic solution, we speculate that ice plant may be valuable for the bioremediation of salinized soil. When consuming ice plant as an edible crop, it is
literature, no information is available regarding associated NO 3 -N loading and associated flow rate profiles and volumes during actual runoff events. This information is particularly important for designing a microbial-based, denitrifying bioremediation
This research focused on the potential use of common cattails (Typha latifolia) for removing metalaxyl and simazine residues from contaminated water. Specifically, it established toxicity thresholds to the herbicide simazine and characterized the uptake and distribution of simazine and metalaxyl by the plants. Simazine tolerance levels were determined by exposing plants to a series of six concentrations (0 to 3.0 mg/L) in aqueous nutrient media for 7 days. Metalaxyl toxicity was not evaluated because other studies indicated it was relatively non-toxic to plants. Toxicity endpoints measured included fresh mass production after 7 days exposure and 7 days post-exposure. Pesticide uptake and distribution were determined by growing plants in nutrient media amended with C-14-ring-labeled metalaxyl (0.909 mg/L) or simazine (0.242 mg/L) for 1, 3, 5, or 7 days. Plants were dissected and tissues were combusted and analyzed by liquid scintillation counting. Cattail fresh mass production was reduced 84% and 117% at 1.0 and 3.0 mg/L simazine, respectively, after 7 days of exposure. Metalaxyl and simazine activity in solution was reduced 34% and 65%, respectively, after 7 days. By day 7, activity from both pesticides was detected predominantly in the leaves. Uptake of each pesticide was correlated with water uptake throughout the 7 days. These results suggest that the common cattail may be a good candidate for incorporation into a phytoremediation scheme for metalaxyl and simazine.
Fertilizer costs and increased awareness of point-source pollution are amplifying the pressures on farming, economics along with public demand for sustainable production methods and organically grown produce. Our research focuses on using effluent from thermophilic anaerobic digestion of poultry litter as an alternative fertilizer. Cucumbers (Cucumis sativus L.) were grown hydroponically using a bato bucket system to evaluate the effects of liquid effluent as a nutrient solution versus a commercial nutrient solution. Seeds of the beit alpha cultivar `Manar' were started in Horticubes and transplanted into buckets containing a perlite/coir media. The effluent fertilizer consisted of effluent diluted to the same ppm nitrogen found in the commercial fertilizer based on ammonium measured in the effluent. Hydroponic solutions were monitored twice a day to maintain a pH of 5.6-6.0. Fruit was harvested three times a week and graded on size and shape. Fruit of each grade were counted, weighed, and recorded. Average fruit weight and fruit number produced was statistically significant between the two fertilizer regimes with the commercial fruit, averaging 84 g compared to 75 g for effluent fruit. The effluent treatment produced a greater percentage of grade 1 fruit (33%) compared to the commercial treatment (26% grade 1 fruit). Thus, 74% of the commercial harvest was grade 2 or cull fruit compared to only 66% of the effluent harvest. Correlating grade with average fruit weight analysis identified statistical differences between treatments for the grade 1 fruit, but not the grade 2 or the culls. While effluent from thermophilic anaerobic digestion shows promise as an alternative hydroponic fertilizer, it is not better than the commercial fertilizer regime.
preferential growth of roots in uncontaminated zones. Bioremediation is a process of using microbes to degrade hydrocarbons. N and other nutrients are needed for bioremediation of hydrocarbon-contaminated soils by microorganisms ( Norris and Dowd, 1993 ). In
Lead pollution is an important issue in the world. Perennial ryegrass (Lolium perenne), as one of the widely used turfgrass and forage species, has a potential for bioremediation. The objective of this study was to investigate how antioxidant enzymes and their gene transcripts respond to Pb stress in perennial ryegrass. Ryegrass seedlings were subjected to 0, 0.5, and 3.2 mm of Pb(NO3)2 for 7 days in a hydroponic system maintained in a greenhouse. Both root and shoot growths were inhibited by Pb compared with the control. However, contents of chlorophyll (Chl) a and total Chl were unaffected by Pb treatment. Results from this study showed a substantial increase of malondialdehyde (MDA) content in leaf tissues when perennial ryegrass was exposed to Pb at 3.2 mm. The MDA content from plants in the 0.5 mm Pb treatment was lower than the control, indicating that an effective defense mechanism existed. Circumstantial evidence came also from the content of soluble protein in 0.5 mm Pb treatment, which was not different from the control. Furthermore, the activity of catalase (CAT) increased at 0.5 mm Pb compared with the control, indicating that CAT might play an important role in scavenging reactive oxygen species (ROS). The expression profiles of eight genes encoding antioxidative enzymes were upregulated within 24 hours of Pb treatment. In conclusion, antioxidant enzymes responded to Pb at an early stage of exposure and their gene expression profiles provided more details in time courses of the activation of those systems.
The major challenge facing society in the 21st century is to feed and provide shelter for increasing numbers of people while protecting human health, our natural resource base, and the environment. To accomplish this, we must combine traditional technologies that stress conservation with modern technologies that rely heavily on biologically based solutions. Biotechnology, by its historical definition, has play an important role in environmental clean-up, but the contemporary practices of biotechnology will lead to more-sophisticated approaches. These technologies will allow clean-up of existing contamination and even prevention of contamination through more-sensitive and accurate monitoring systems. One of the most important advances is in bioremediation, in which microorganisms and plants remove contaminants from the soil or water and concentrate of volatilize them. In addition, plants are being modified through the changing of single genes so that they are less susceptible to pathogenic microorganisms, viruses, or insects, and more efficient in nitrogen utilization. The use of such modified plants, in concert with good agricultural practices, should lead to reductions in chemical inputs of pesticides and fertilizers. Strategies have also been developed that permit the “manufacture” in plant “pharms” of industrial products that are now produced through the use of nonrenewable resources. These biological approaches are part of the cadre of tools that we need to solve the problems of the next century. In addition, these tools will be instrumental in understanding the basic biological systems upon which the solutions to many of these challenges will come. Biotechnology is not a technological fix, but it should form part of the mind-set from which we design our strategies.
The use of microbes and/or microbial processes for the bioremediation of soils contaminated with pesticides is an idea that has enjoyed considerable interest over the past several years. Many microbes with specific pathways for the degradation of particular pesticides, or classes of pesticide, have been isolated and characterized. Unfortunately, most sites that are heavily contaminated with pesticides contain a mixture of the many different types of pesticides that have been used over the last 5 decades. This complex mixture of compounds may inhibit microbial degradation or may require multiple treatments to assure that all the chemicals are degraded. Treatment of wastes before they contaminate the environment is one way to avoid the problems associated with mixed wastes. We have isolated a number of microorganisms that detoxify insecticides, such as carbaryl of parathion via the action of hydrolase enzymes. These enzymes can be used to treat waste pesticide solutions before disposal. A system was developed for the disposal of one high-volume organophosphate insecticide waste by treatment with parathion hydrolase, followed by ozonation to yield harmless products that were readily degraded by other soil microorganisms. A second method for disposal of this waste involves altering the environmental conditions in the waste to stimulate the growth of microorganisms naturally present in the material utilizing the pesticide as a carbon source. This accomplishes degradation of the material over a 2-week period. Many, if not all, pesticides are degradable to some degree by microorganisms, and this fact can be exploited to provide cost-effective methods for the safe disposal of pesticide wastes.
Various soilless substrate components have been evaluated for many years to identify sustainable resources that do not negatively impact plant growth. Biochar is a carbon-based material that has been evaluated for use as an alternative aggregate in peat-based soilless substrates. In addition, the use of carbon adsorption for compound removal is widely used in groundwater remediation, municipal water filtration, and volatile organic compounds. Experiment one aimed to determine the impact of coarse biochar (<6 mm) on paclobutrazol efficacy when incorporated at 15% or 30% by volume in a peat-based substrate when compared with a perlite-amended substrate at the same incorporation volumes. In Expt. 1, a single paclobutrazol drench application of 0, 0.5, 1.0, 2.0, and 4.0 mg·L−1 was applied to ‘Princettia Red’ and ‘Princettia White’ poinsettias (Euphorbia pulcherrima × Euphorbia cornastra). In Expt. 2, two different biochar particle sizes of coarse (<6 mm) and extra coarse (>6 mm) were examined at the same incorporation volumes as Expt. 1 and compared with a perlite-amended substrate at the same incorporation volumes. However, during Expt. 2, continual drench applications at times of irrigation of 0.0, 6.25, 12.5, 25.0, 50, and 100 μg·L−1 (ppb) paclobutrazol were applied to pansy (Viola ×wittrockiana) ‘Matrix Blue Blotch’ and begonia (Begonia ×hybrida) ‘Big Red Bronze Leaf’. The efficacy of paclobutrazol drenches for controlling growth in all species was unaffected by the substrate composition regarding aggregate type or aggregate incorporation rate. Thus, even though biochar is often used for bioremediation and wastewater treatment, it did not negatively impact the efficacy of paclobutrazol drenches at the concentrations used. This research suggests that when biochar is used as an amendment to peatmoss it will not influence paclobutrazol drench efficacy when incorporated up to 30% by volume for the examined species.
reestablishing method is yet to be identified for damages in cool-season lawns caused by diesel or hydraulic fluid spills. Bioremediation is a process of using microbes to degrade hydrocarbons ( Aislabie et al., 2006 ). Nitrate nitrogen added to soils