Spatial patterns and storage of organic chlorine and chloride in coniferous forest soil in south-east Sweden

The concentration and storage of organic chlorine and chloride were determined in soil, to a depth of 40 cm, in a coniferous forest in the Stubbetorp catchment area in south-east Sweden. Also, the spatial distribution of the two forms of chlorine was determined. Soil samples were collected at 49 of the nodes in a grid with approximately 105 m between the nodes. The analysis of spatial variability suggested that no spatial autocorrelation was present either within the variable organic chlorine or chloride. This means that no sample was more influenced by another nearby sample, as compared to other samples further away. Instead, linear interpolation was used to construct contour maps of the concentrations. The contour maps indicated that the two forms of chlorine have similar spatial patterns and the highest concentrations could be found in the main valley area, with moss soil and forest dominated by pine (Pinus sylvestris (L.)). The two variables showed a significant positive correlation. This could be due to the fact that chloride is the limiting factor for formation in Swedish soil or that the two forms of chlorine are only indirectly related through variables as soil moisture or organic matter. The storage of organic chlorine when a depth of 40 cm was taken into account was seven times the storage compared to an earlier study where only the top-soil was sampled. The storage of organic chlorine in the area is of such size that changes in this storage are likely to have an impact on the transport of chloride. The fact that no spatial autocorrelation could be found in either of the variables suggests that the scale chosen is not suitable for describing spatial autocorrelation on a smaller level, due to processes e.g. microbially induced formation. At the same time the chosen scale is probably too small for detecting spatial autocorrelation on the larger scale due to e.g. deposition and precipitation