The physical regime and the respective biogeochemical processes in the lower water mass of Lake Kinneret

Physical measurements made in Lake Kinneret, during the stratified period, indicate that the lower water mass (LWM) consists of two layers: a turbulen t benthic boundary layer (BBL) and a hypolimnetic layer overlying the BBL. The water in the LWM moves in response to vertical mode one seiching of the metalimnion; this movement is accentuated near the perimeter of the metali mnion due to shoaling of the seiche and breaking of internal waves. The mot ion associated with this phenomena induce a well mixed benthic boundary lay er (BBL) adjacent to the lake bottom. The BBL and hypolimnion were distingu ished chemically because transport of solutes between these water bodies wa s very small. Compared to the hypolimnion, the BBL was characterized by mor e intensive biomineralisation processes as indicated by the faster depletio n of DO and NO3, by higher levels of NH4, H2S, and soluble reactive phospho rus (SRP) and by lower pH values. SRP levels in the hypolimnion were partic ularly low, suggesting that phosphorus was either preferentially removed by sedimentation from the hypolimnion, or it was not released from particles. As a result NH4 over SRP ratios in the hypolimnion were significantly high er than in the BBL and diffusional fluxes of both nutrients from the LWM to the trophogenic epipelagic water, should therefore be characterized by rel atively high N/P ratios.