A Radio and X-Ray Study of Historical Supernovae in M83

We report the results of 15 years of radio observations of the six historical supernovae (SNe) in M83 using the Very Large Array. We note the near linear decline in radio emission from SN 1957D, a type II SN, which remains a non-thermal radio emitter. The measured flux densities from SNe 1923A and 1950B have flattened as they begin to fade below detectable limits, also type II SNe. The luminosities for these three SNe are comparable with the radio luminosities of other decades-old SNe at similar epochs. SNe 1945B, 1968L, and 1983N were not detected in the most recent observations and these non-detections are consistent with previous studies. We report the X-ray non-detections of all six historical SNe using the Chandra X-ray Observatory, consistent with previous X-ray searches of other decades-old SNe, and low inferred mass loss rates of the progenitors.Comment: 3 color ps figure

Carbon Capture and Water Emissions Treatment System (CCWESTRS) at Fossil-Fueled Electric Generating Plants

The Tennessee Valley Authority (TVA), the Electric Power Research Institute (EPRI), and the Department of Energy-National Energy Technologies Laboratory (DOE-NETL) are evaluating and demonstrating integration of terrestrial carbon sequestration techniques at a coal-fired electric power plant through the use of Flue Gas Desulfurization (FGD) system gypsum as a soil amendment and mulch, and coal fly ash pond process water for periodic irrigation. From January to March 2002, the Project Team initiated the construction of a 40 ha Carbon Capture and Water Emissions Treatment System (CCWESTRS) near TVA's Paradise Fossil Plant on marginally reclaimed surface coal mine lands in Kentucky. The CCWESTRS is growing commercial grade trees and cover crops and is expected to sequester 1.5-2.0 MT/ha carbon per year over a 20-year period. The concept could be used to meet a portion of the timber industry's needs while simultaneously sequestering carbon in lands which would otherwise remain non-productive. The CCWESTRS includes a constructed wetland to enhance the ability to sequester carbon and to remove any nutrients and metals present in the coal fly ash process water runoff. The CCWESTRS project is a cooperative effort between TVA, EPRI, and DOE-NETL, with a total budget of $1,574,000. The proposed demonstration project began in October 2000 and has continued through December 2005. Additional funding is being sought in order to extend the project. The primary goal of the project is to determine if integrating power plant processes with carbon sequestration techniques will enhance carbon sequestration cost-effectively. This goal is consistent with DOE objectives to provide economically competitive and environmentally safe options to offset projected growth in U.S. baseline emissions of greenhouse gases after 2010, achieve the long-term goal of$10/ton of avoided net costs for carbon sequestration, and provide half of the required reductions in global greenhouse gases by 2025. Other potential benefits of the demonstration include developing a passive technology for water treatment for trace metal and nutrient release reductions, using power plant by-products to improve coal mine land reclamation and carbon sequestration, developing wildlife habitat and green-space around production facilities, generating Total Maximum Daily Load (TMDL) credits for the use of process water, and producing wood products for use by the lumber and pulp and paper industry. Project activities conducted during the five year project period include: Assessing tree cultivation and other techniques used to sequester carbon; Project site assessment; Greenhouse studies to determine optimum plant species and by-product application; Designing, constructing, operating, monitoring, and evaluating the CCWESTRS system; and Reporting (ongoing). The ability of the system to sequester carbon will be the primary measure of effectiveness, measured by accessing survival and growth response of plants within the CCWESTRS. In addition, costs associated with design, construction, and monitoring will be evaluated and compared to projected benefits of other carbon sequestration technologies. The test plan involves the application of three levels each of two types of power plant by-products--three levels of FGD gypsum mulch, and three levels of ash pond irrigation water. This design produces nine treatment levels which are being tested with two species of hardwood trees (sweet gum and sycamore). The project is examining the effectiveness of applications of 0, 8-cm, and 15-cm thick gypsum mulch layers and 0, 13 cm, and 25 cm of coal fly ash water for irrigation. Each treatment combination is being replicated three times, resulting in a total of 54 treatment plots (3 FGD gypsum levels X 3 irrigation water levels x 2 tree species x 3 replicates). Survival and growth response of plant species in terms of sequestering carbon in plant material and soil will be the primary measure of effectiveness of each treatment. Additionally, the ability of the site soils and unsaturated zone subsurface materials will be evaluated for their effectiveness at treating the irrigation water for various pollutants