Territory of Ventspils harbour (the Baltic Sea)

Inorganic chemical composition of sediment or rocks

Sediment grabs; inductively-coupled plasma atomic emission spectroscopes; inductively-coupled plasma mass spectrometers

The aim of the H-SENSE (Harbours - Silting and Environmental Sedimentology) project is to develop a predictive sedimentological model for the management of harbour activities with regard to silting and the evaluation of environmental pollution. The applications of this modelling, especially dredging procedures and traffic management, will have importance for both the industrial potential and the overall environmental health of such harbour waters and adjacent regions. The survey methods tested here will give a sediment perspective to hydrographic surveys for the evaluation of both navigable depths within soft sediments and the alternatives responses to harbour silting. Using a sediment perspective to combine with, and to show the net effects of, hydrologic fluxes, we will evaluate the natural and anthropogenic sediment sources, transport pathways, and geochemical changes that involve pollutants. Particular emphasis will be given to the effects of sediment mixing by harbour traffic and dredging activities. In this connection, the introduction of water-jet propulsion systems may crucially change the balance of erosion and silting processes and the resulting sediment storage time in many harbours. Harbours with low tidal influence are often effective sedimentation traps, and their soft-bottom floors are particular vulnerable to new turbulence. These natural sediment traps can therefore provide a cleansing function for river and coastal environments. By using low-tidal settings, we can compare sediment accumulations from relatively undisturbed sites as a base line control for the natural changes expected through time. We will use two harbour studies to develop the generic model (Göteborg, Sweden, and Bergen, Norway), and a third example (Ventspils, Latvia) for model testing. Pollutant mobility is linked partially to sediment fluxes, but also to the geochemical conditions that develop within the bottom sediments arising from organic degradation and oxidant depletion. The dangers of both catastrophic and diffuse spillage of pollutants are well recognized. Less obvious, but nevertheless very important, is the release of pollutants that have previously accumulated within the sediments. As considered further below, both negative and positive effects can be anticipated in connection with such exchange across the water-sediment interface, and with the precipitation and dissolution of solid phases. Consideration of the particular sedimentological character for each setting will, hopefully, lead to the optimum management for both silting and pollution control. Objectives 1. Identification of the sediment sources, transport pathways and deposition in a harbour setting having limited tidal influence. 2. Evaluation of the geographic and vertical associations between sediment components and the geo-chemical transfer mechanisms involving pollutants, with particular reference to bottom turbulence. 3. Establishment of a generic model for component and process quantification, and to suggest model scenarios involving dredging and environmental change in harbour settings. During the two years of the H-SENSE project there will be three workshops (tentatively 4/98, 1/99 and 11/99). The workshops are closely connected with the three Work Packages and will offer a fitting medium for monitoring progress, i.e. serve as milestones. The deliverables associated with each milestone stage (and related Work Package) will be included in the themes for these workshops, and their fulfilment will be summarized in the workshop statement. Each workshop will consist of scientific presentations, discussions, and detailed project planning. In addition to the statement regarding the project status, the extended abstracts of each presentation will provide an initial documentation of results and ensure partner awareness of the overall objectives and interrelationships.

Latvian Institute of Aquatic Ecology
Voleru str.4
Riga

LV-1007
Latvia