, J. 2006. Runoff phosphorus retention in vegetated field margins on flat landscapes. Can. J. Soil Sci. 86: 871-884. Vegetated buffer strips (VBS) are often recommended as a management practice that farmers can use to help mitigate the environmental effects of runoff from agricultural fields. Previous research has shown that VBS can be effective at trapping phosphorus (P) and other farm-sourced environmental contaminants. This project measured the effectiveness of established vegetated strips at decreasing P in runoff from agricultural fields in Manitoba. Paired samples of runoff, taken at the field edge and in the vegetated strip, indicated that in 11 of the 22 cases sampled (50%), P concentrations in the runoff decreased (on average 30%) as the flow passed through the vegetated strip. In 7 of the 22 case (32%) there was no difference; however, in four of the 22 cases (18%), runoff P concentrations increased, indicating the vegetated strip had become a source of runoff P. Soil samples from the VBS showed high available P concentrations at positions within the vegetated strip along the runoff flow path, and in 7 of 10 cases these concentrations were higher (33% on average) than in the field soil. Although the observations and numerical results suggest that VBS can be effective at removing P in runoff, perhaps the major limitation in this flat-land region is that runoff tends to flow through rather small portions of the VBS, and these may not have sufficient capacity to retain the runoff P in the longer term. Le projet devait établir l'utilité de telles bandes de végétation pour réduire la concentration de P dans les eaux de ruissellement issues des cultures, au Manitoba. Les couples d'échantillons d'eau de ruissellement prélevés en bordure des champs et dans la bande enherbée indiquent que la concentration de P dans les eaux de ruissellement diminue (d'en moyenne 30 %) dans 11 cas sur 22 (50 % des échantillons) lorsque l'eau traverse la bande de végétation. Aucune variation n'a été notée dans sept cas (32 %) alors que dans quatre autres (18 %), les auteurs ont relevé une hausse de la concentration de P, signe que la bande enherbée devenait elle-même une source de P lors du ruissellement. Les échantillons de sol tirés des bandes enherbées révèlent une concentration élevée de P disponible aux endroits situés le long du trajet suivi par les eaux et, dans sept cas sur dix, la concentration était plus élevée (d'en moyenne 33 %) que dans le sol cultivé. Bien que ces observations et les données quantitatives laissent croire à l'efficacité des bandes enherbées pour retenir le P présent dans les eaux de ruissellement, le principal problème de cette région au relief plat est peut-être que les eaux ont tendance à ruisseler à travers de petites sections des bandes de végétation, dont la capacité de rétention pourrait s'avérer insuffisante à plus long terme.

Abstract. Application of forward coastal sediment transport models in situations involving large temporal and spatial scales or topographically complex environments can be highly problematic since the distribution of hydrodynamic parameters is rarely adequately known. Where rocky topography is present, flow patterns may be altered and sediments trapped by topographic barriers. A frequently employed approach to these problems is the application of the statistical technique known as empirical orthogonal function (EOF) analysis. One limitation of EOF analysis of grain size and mineralogical data is that EOF is a purely geometric technique which does not allow incorporation of a priori knowledge we may have regarding the physical environment. In fact, there is no guarantee that a meaningful physical interpretation of the results of an EOF analysis actually exists. This is not true of geophysical inverse theory, which is capable of incorporating diverse forms of information and is not limited to purely geometric manipulations of data. We have formulated an inverse theoretical approach to study sediment transport which we call STI, short for source-transport inversion.

W Biological communities (benthos) can have a major impact on the stability of marine sediments. The Paper reviews laboratory results obtained using species and sediment from the upper Clyde Estuary. The impact of these results on predicting sediment processes in the coastal zone is also discussed. New relationships are presented that relate the population of two marine organisms (Nereis diversicolor and Corophium volutator) to increased sediment shear strength.

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