Hydrological Control of Phosphorus Mobility in Altered Wetland Soils.
Michael Litaor, Tel-Hai College, Dep. Biotech. & Environ. Sci., Tel-Hai Academic College, Upper Galilel, Israel
Groundwater transport of phosphorus (P) from the altered wetland soils of the Hula Valley may influence the water quality of Lake Kinneret, which provides up to 30% of the potable water for the state of Israel. This study was conducted to evaluate P mobility from the Hula's wetland soils to waterways under various hydrological conditions using a field-scale experiment (0.8 km2) with well-monitored boundary conditions. The spatio-temporal changes in hydraulic head across the study area were measured using automated monitoring stations installed in eight observation wells. The hydraulic conductivity (K) of the near-surface peat/marl layers (179 m d-1) was significantly larger than the K values (0.001 to 0.03 m d-1) measured in the marl layers at 5 to 15 m below surface. The large K values of the near-surface layers result from the drainage of this wetland in the late 1950s followed by the oxidation of the peat layers and dissection of the lower peat and upper silt-clayey marl layers. Using a simple water-budget approach, the large field experiment yielded a discharge of 0.27 Mm3 and a loading of 306 kg P transported from the altered peat soils to the waterways, in just 7 weeks. Most of the P loading was in the form of particulate P (> 0.45 Ám) rather than dissolved P.