Agro-industrial wastewater and municipal sewage wereused to restore Frank Lake, a 1246 ha northernprairie marsh in southern Alberta, Canada, to providewaterfowl habitat and improve water quality. Meanannual inflow wastewater nutrient concentrations were17 mg L-1 NH3-N, 30 mg L-1 NO3-Nand 11 mg L-1 SRP. Mean flows greater than 5000 m3 day-1 loaded the marsh with 23 000 kg of P annually. Summer NH3-N, NO3-N andtotal phosphorus (TP) surface water concentrationswere decreased by 76, 87 and 64%, respectively, aswaters flowed through the first basin of the marsh.Winter treatment was less successful, with surfacewater NH3-N, NO3-N and TP reductions of46, –26 (export) and 26%, respectively.Short-circuiting of water flow through the marsh andcold seasonal conditions with ice cover caused spatialand temporal variation in marsh treatment. Continuedhigh loadings to the marsh may lead to sediment saturation, eutrophication or phosphorus export from the marsh.

Over the past decade, a growing concern has developed about the potential impacts of carbon dioxide (CO2) emissions on the future global environment. Much of this concern has focused on the coal-fired power plants that now produce 56 percent of U.S. electricity. The main reason for the continued use of coal as the major power plant fuel in the U.S. is its significantly lower cost compared to other fossil fuels. There are several choices of power plant fuels available today including coal, oil, and natural gas. Since deregulation of the electric utility industry was initiated several years ago, the use of natural gas by electricity generating companies has steadily grown. Coal use is projected to continue to rise slowly in the U.S. as the total amount of electricity that is generated increases. As a result, the coal-fired option for new electricity generating plants remains important to utility generating companies that have been historically dependent on coal for the bulk of their power generation. However, there have been recent indications that permissible levels of CO2 emissions may be curbed in the future. A natural gas-based power plant will produce less CO2 per kW of power output compared to a coal-based plant with the same net plant power output. This is due to two fundamental factors: (1) natural gas has a lower carbon-to-hydrogen ratio compared to that of coal for the same level of thermal input, and, (2) natural gas-based systems have higher powergenerating efficiencies compared to coal-based systems utilizing the same, or similar, power generation equipment. In conventional gas and coal-fired units, CO2 can be removed from the exhaust gas following heat recovery in an absorber/stripper system. As such, the partial pressure of CO2 is usually low due to the near ambient pressure of the stack gas as well as the dilution effect of substantial amounts of N2 contained in the flue gas. Low CO2 partial pressure yields large and costly removal equipment. However, advanced coal-based technologies, such as gasification -because they produce concentrated streams of CO2 at high pressure -offer convenient opportunities that may be exploited for low-cost CO2 removal. In an oxygen-blown integrated gasification combined cycle power plant, CO2 may be removed from the synthesis gas prior to combustion power generation. The high pressure of the synthesis gas stream, as well as the absence of diluent N2, yields high CO2 partial pressures. This, in turn, results in a relatively cheaper separation due to increased driving force. Innovative coal gasification-based systems may therefore be the most cost-effective coal-based power plants if CO2 removal is required. The objective of the work presented in this paper is to evaluate preliminary designs of several advanced coal-fired power plants to determine whether they have the potential to be competitive, in the period after year 2010, with conventional natural gasand coal-fired power plants. Future conventional natural gas-fired power plants are assumed to be H class combined cycles. Conventional coal-fired plants are assumed to be pulverized coal (PC) supercritical steam power plants. Each power plant concept evaluated was configured both with and without a CO2 removal system. For the advanced coal-fired power plant designs that meet competitive cost targets, DOE will define the R&D effort required to develop and demonstrate the technology to be a commercially attractive alternative.

The ability of wetlands to function as sinks for phosphorus (P) has been the subject of much debate. We measured the ability of a 1246 ha restored northern prairie wetland to store P from beef slaughter and municipal sewage wastewater. Sediment cores were collected from the Frank Lake marsh to quantify P accumulation, sedimentation rates and sediment adsorption ability. Approximately 60% of P inputs into the marsh since restoration in 1990 have been stored in the sediments (79 662 kg out of 141 760 kg applied). Sites near the wastewater inflow had greater sedimentation rates (3.0 cm year(-1)) and P burial rates (38.5 g P m(-2) year(-1)) than other sites across the marsh (24 g P m(-2) year(-1)). Surface sediments from the marsh and reference wetlands were collected and spiked experimentally with 25-500 mu g l(-1) P (as NaH(2)PO(3)(4-)) to determine the ability of the sediments to take up additional P. Sorption isotherms showed that the sediments near the inflow had a limited ability for additional P-sorption. When exposed to 500 mu g l(-1) P, inflow sites sorbed a maximum of 1000 mu g P g sediment(-1). In contrast, the rest of the sites in the marsh sorbed up to 1700 mu g P g sediment(-1), while nearby reference wetland sites sorbed more than 2500 mu g P g sediment(-1). Approximately 66% of the marsh sediments still had high sorption ability. Inflow sites had a reduced ability for additional P uptake due to the high P loadings applied to that area. Frank Lake has provided effective P retention, however, future treatment efficacy may decrease if the remaining sediments become saturated. Continued high P loading to the marsh may lead to eutrophication problems and downstream P export from the wetland. (C) 2000 Elsevier Science B.V. All rights reserved.

/day (800,000 US gallons) of municipal wastewater and beef processing wastewater. A large nongovernmental organization hastened restoration with a development process that outlined restoration goals and management objectives to satisfy a dual mandate of wastewater treatment and wildlife habitat creation. In 1995, after five years of wastewater additions, the basins had been refilled and the surrounding uplands had been acquired and restored. The Frank Lake Conservation Area currently provides high-quality habitat for a variety of wildlife in a region where many of the native plants and animals species have been lost due to habitat loss and fragmentation. The success of upland and water management strategies is reflected in the increase of target species' abundance and richness: 50 shorebird species, 44 waterfowl species, 15 raptor species, and 28 other new bird species have returned to the marsh since restoration. As well, significant N and P reduction occurs as waters flow through the first basin of the marsh. The management strategies of this project that satisfied a dual mandate serve as a model to guide managers of other large-scale wetland restoration projects.