Nitrification Potential and Factors Governing the Rate of Nitrification in Lake Kinneret

Abstract

The nitrification potential (NP) of the water and sediments of Lake Kinneret (Israel) was measured biweekly for a period of 2 yr. The process of nitrification includes a lag period of variable duration. This lag period depends on the number of nitrifying bacteria initially present in the sample. This finding allowed the calibration of the NP measurements in terms of number of nitrifying bacteria. The fluctuations of the NP values were compared with the nitrification actually occurring in the lake. A concomitant decrease of NP in the sediment and increase of the NP in the lake water was observed during the turnover. This may indicate that the mixing of the upper layer of the sediments causes the distribution of the bacterial inoculum in the lake water. The decrease of the NP at the end of the mixing period is due to the cessation of the water circulation and the grazing of Cladocera on the nitrifying bacteria.