|
|
Silica, nitrate, total and dissolved phosphorus, and conductivity were measured during spring and summer in Lake Powell, Utah-Arizona. Phytoplankton productivity was also de- termined. Conductivity is used as a tracer for delineating the advective influence of inflows from the Colorado and San Juan Rivers on nutrient delivery and distribution in the reservoir. High spring runoff (1,000-2,000 m3 s-') enters the lake essentially as an overflow and dom- inates the nutrient cycle in the epilimnion. The interaction of advective nutrient delivery and high turbidity controls the distribution of phytoplankton productivity and nutrient depletion. Published in Limnology and Oceanography, volume 25, issue 2, on pages 219 -...
|
Flameless atomic absorption analyses of samples from Lake Powell yield mean mercury levels in ppb of 0.01 in water, 30 in bottom sediments, 10 in shoreline substrates, 34 in plant leaves, 145 in plant debris, 28 in algae, 10 in crayfish, and 232 in fish muscle. Trout were unique in having lower concentrations in muscle than in highly vascularized blood tissues. Concentrations increased with increased body weight and higher levels on the food chain. Muscle of some large fish over 2 kg whole body weight exceeded 500 ppb. Bioamplification of mercury up the food chain and association of mercury with organic matter are demonstrated. Published in Environmental Science & Technology, volume 9, issue 1, on pages 41 - 46,...
|
|
