Prairie pothole marshes as traps for nitrogen and phosphorous in agricultural runoff

Water quality of drainage influents and the lone effluent at Eagle Lake marsh, Iowa, was studied for 4 years (1976-1979). Because of drought conditions, there was no effluent from the marsh in 1976, 1977, or 1978. In 1979, the marsh was effective at removing inorganic N, especially N03-N, from runoff water passing through. It had little impact on levels of inorganic-P, total-P, and Kjeldahl-N; it was a net exporter of soluble organic carbon

Perspectives on the Delta Waterfowl Research Station-Ducks Unlimited Canada Marsh Ecology Research Program

Present wetland management has been developed largely on a trial and error basis (Figure 1 ). The effects of many important environmental variables on wetland productivity 253 are not known, consequently management results have not been predictable with a high degree of accuracy (Weller 1981 ). Many marsh management techniques have been described; however, consistently successful marsh management requires a more comprehensive understanding of the structure and function of wetland systems. Although there have been numerous observational studies, major advances in our understanding will result from tightly controlled experimentation which permits the integration of simultaneous research efforts by a number of different scientific disciplines (Reichle 1975, Weller 1978). Because wetlands are temporally dynamic, this type of multi-disciplinary ecosystem analysis must also span a number of years to document the annual and long-term variability within the system. By better understanding the structure and function of wetlands, managers will be better able to design management techniques and strategies suited to their particular situation and therefore realize greater success in manipulating the productivity of these systems (Figure I)

Transformation and fate of nitrate and atrazine in freshwater wetlands

Agricultural chemical contamination of surface and groundwater is a special concern in the Midwest. Nutrient loads to surface waters in this region are among the highest in the country, and contamination of surface and groundwater occurs from a variety of pesticides. In addition to improved farming systems that incorporate Best Management Practices and reduced inputs of nutrients and pesticides, the creation of buffer strips and other off-field sinks for chemical contaminants near their origin offers great promise for minimizing surface and groundwater contamination. In the Corn Belt, one of the most promising off-field strategies for reducing contamination of surface and groundwater is the restoration of wetlands in agricultural watersheds, specifically as sinks for agricultural chemical contaminants

High-Tech Urban Agriculture in Amsterdam : An Actor Network Analysis

The agriculture and horticulture sector in the Netherlands is one of the most productive in the world. Although the sector is one of the most advanced and intense agricultural production systems worldwide, it faces challenges, such as climate change and environmental and social unsustainability of industrial production. To overcome these challenges, alternative food production initiatives have emerged, especially in large cities such as Amsterdam. Some initiatives involve producing food in the urban environment, supported by new technologies and practices, so-called high-tech urban agriculture (HTUA). These initiatives make cultivation of plants inside and on top of buildings possible and increase green spaces in urban areas. The emerging agricultural technologies are creating new business environments that are shape d by technology developers (e.g., suppliers of horticultural light emitting diodes (LED) and control environment systems) and developers of alternative food production practices (e.g., HTUA start-ups). However, research shows that the uptake of these technological innovations in urban planning processes is problematic. Therefore, this research analyzes the barriers that local government planners and HTUA developers are facing in the embedding of HTUA in urban planning processes, using the city of Amsterdam as a case study. This study draws on actor-network theory (ANT) to analyze the interactions between planners, technologies, technology developers and developers of alternative food production practices. Several concepts of ANT are integrated into a multi-level perspective on sustainability transitions (MLP) to create a new theoretical framework that can explain how interactions between technologies and planning actors transform the incumbent social\u2013technical regime. The configuration of interactions between social and material entities in technology development and adoption processes in Amsterdam is analyzed through the lens of this theoretical framework. The data in this study were gathered by tracing actors and their connections by using ethnographic research methods. In the course of the integration of new technologies into urban planning practices, gaps between technologies, technology developers, and planning actors have been identified. The results of this study show a lacking connection between planning actors and technology developers, although planning actors do interact with developers of alternative food production practices. These interactions are influenced by agency of artefacts such as visualizations of the future projects. The paper concludes that for the utilization of emerging technologies for sustainability transition of cities, the existing gap between technology developers and planning actors needs to be bridged through the integration of technology development visions in urban agendas and planning processe