TEMPORAL CHANGES IN PORE WATER CHEMISTRY IN THE PEAT DEPOSIT OF A RAISED BOG

摘要

The contents of Ca, Mg, Na, K, also pH and electric conductivity were monitored during the drought year of 1999 and the wet year of 2000 on the Mannikjarve bog (ca 180 ha, Central Estonia) with an aim to understand seasonal changes in the spatial dynamics of peat pore water chemistry in the peat deposit. Twenty-four sets of piezometric tubes were installed at different depths (from 0.9 to 7 m) into the peat deposit on three cross-transects over the bog massif. The element concentrations in the deeper part of deposit showed essential temporal fluctuations especially during the drought summer with extremely high Ca content peaks (up to 77 mg l~(-1)). This phenomenon could be explained with groundwater discharging upward to the peat deposit.