Spatial modeling in sediments
Danielsson, Åsa K. 1998
Linköping university (Sweden), 90 pp.

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In a marine environment the sediments play an important role. They act as sinks, where the concentrations often are higher than in the water mass above, but also as sources for numerous pollutants. Two of the major groups of contaminants are metals and nutrients. While the metals may be harmful even in rather small concentrations the latter are mainly studied due to their importance in eutrophication. Three study areas are used - the Baltic Sea, Kattegat and Skagerrak - which are effected by heavy metal pollution and high nutrient loads. The sediments, in these areas, can not be seen as homogeneous. Spatial distribution, scales, patterns, covariation between different substances and other characteristics of nutrients and metals in the sediments give important information on e.g. deposition processes and sources. It is revealed that point sources do not have any major influence on the distribution of metals and nutrients in the sediments. Instead it seems like biogeochemical processes mainly control the patterns found. In all three areas, carbon and nitrogen give similar patterns, indicating similar deposition processes. It is harder to determine correlation scales in Kattegat than in Skagerrak, where the latter has longer scales. This is also seen for the metals where e.g. cadmium, copper and mercury have less clear scales than both carbon, nitrogen and lead, which may be interpreted as a result of different sources and behaviour of substances. The results suggest that spatial analysis is important in when analysing the sediments. Spatial dependence should not, as often is common nowdays, be neglected as it incorporates relevant knowledge on distributions, scales, representativity, dependece and interrelation within and between variables and locations. Spatial analysis is also valuable when designing more cost-effective monitoring programs.