Vertical distribution and transport of molybdenum in a lake with a seasonally anoxic hypolimnion, Limnol

Distribution and trends of MO concentrations in the seasonally anoxic Lake Greifen were investigated over 15 months. MO in water samples and settling particles was determined by catalytic adsorption polarography and inductively coupled plasma mass spectrometry. MO concentrations in the epilimnion were usually homogeneous at-0.48 pg liter- I. A significant decrease with depth was found during the stratification period. The lowest MO concentrations (0.31 pg liter-l) were found in the presence of H,S near the sediment. A vertical flux of particle-bound MO of 1.1-4.6 pg m-2 d-l was found. The MO concentration-depth profiles result from a combination of different transport mechanisms that are com-pared by computer model calculations. Under oxic conditions, the vertical distri-bution of molybdenum in natural waters is highly conservative. Such a behavior was ob-served in the Pacific Ocean (Collier 1985; Na-kayama et al. 1989) and in Lake Constance (Stabel et al. 199 1). The most abundant specie