THE RELATIONSHIP BETWEEN DISSOLVED ORGANIC-MATTER AND PERCOLATION WATER CHEMISTRY IN NORTHERN FINLAND

The aim of this study was to investigate the relationship between diss olved organic matter and chemical constituents of percolation water co llected at 5, 20 and 40 cm depths from 13 ion-balance sampling plots l ocated along lines extending through Finnish Lapland from Cu-Ni smelte rs in the Kola Peninsula, Russia. All the monitoring plots have as uni form as possible stand and site characteristics, The plots were locate d in Scots pine stands on dry and dryish sites with genetic horizons c haracteristic of Fe-humus podsols. The soil type on most of the sites was sorted fine sand or sand. Significant positive correlations were f ound between dissolved organic matter (DOM) and total dissolved Al con centrations at 5 and 20 cm, but not at 40 cm. A significant negative c orrelation was found between DOM and pH at 5 cm, but not at 20 or 40 c m. The anion deficit was positively correlated with DOM at 5 cm in the percolation water. Organic matter thus plays an important role as an anion in percolation water, and regulates water pH in the surface soil . A high proportion of dissolved Al was in the form of organic complex es. Total dissolved Al levels were well below the toxic limits for pin e.