The concept of the perilimnion

Abstract

Seasonal variations in surface and ground water supply and increasing attention to ionic and mass balances in aquatic eco-systems require more specific definitions of hydrologic parameters to recognize sources and sinks for biologically significant geochemistry. The term "Perilimnion" is proposed to define that zone of the catchment in which groundwater developed by surface runoff and percolation may enter (or leave) the limnic environment. The perilimnion, therefore, is an aquifer, whose geochemistry may affect, or be affected by, the waters of a lake. The term "Tardelimnion" is proposed to define that portion of the limnicenvironment in which deposition of limnogenic sediments (autochthonous or allochthonous) contribute to an aquitard, whose low coefficient of hydraulic permeability (<10-6 cm-1) virtually precludes significant hydrologic or geochemical interaction between lake and ground waters.