Interactions of dissolved and particulate nitrogen in lake metabolism

Abstract

Weekly measurements of dissolved ammonia, nitrite, and nitrate for 22 months and organic nitrogen for 12 months were made in two hardwater lakes and seasonally in four other lakes representing a chemical and trophic spectrum in glaciated Michigan. Seston at 1 m depth was fractionated weekly for 14 months using 10 um Nitex netting in two lakes representing extremes of hardwater productivity.Net and nanno fractions were analyzed by micro-Kjeldahl digestion for organic nitrogen. Seasonal changes in all nitrogenous parameters were subsequently related to changes in fifteen other chemical and biological parameters assayed simultaneousl y.More than half of total sestonic pigments, algal cell volume, and organic nitrogen were present all year in the nannosestonic fraction in the unproductive and productive lake. These data supported the hypothesis that nannophytoplankton contain more nitrogen per unit cell volume than netphytoplankton. DISTRIBUT ION OF THIS DOCUMEN T IS UNLIMITEDfl DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. DISCLAIMERPortions of this document may be illegible in electronic image products. Images are produced from the best available original document.

Role of calcium carbonate precipitation in lake metabolism

“…This sedimentation pattern suggested diatoms were primarily involved and agrees with data from Manny (1971) and unpublished algal data Examination of seston by light microscope and scanning electron microscopy showed large numbers of diatom frustules were present on the filters (Figures 18a, 18b; and 19a, 19b) …”

“…Nitrogen levels are high in Lawrence Lake and nitrogen accumulates in the hypolimnion (Manny, 1971); epilimnetic productivity is not inhibited by lack of nitrate.…”

Nutrient additions by waterfowl to lakes and reservoirs: predicting their effects on productivity and water quality

“…In -1972, the lake was nearly surrounded by oak (Quercus), spruce (Picea), and pine (Pinus) trees and the drainage basin included 40 ha of cultivated fields, 80 ha of fallow fields, and forest (Manny, 1971). Each year, thousands of migrant geese added more than 4400 dry kg of feces to the lake, accelerating processes that fill the lake with sediment (Manny et al, 1975;.…”

“…Nutrient loads to Wintergreen Lake from other external sources were estimated as follows. Water entered the lake as precipitation, watershed runoff, and effluents from a cattle feedlot and a school septic field that each flowed 21 min-' (Manny, 1971). We assumed groundwater inflow to the lake was negligible because its basin was sealed by up to 7 m of calcium carbonate .…”

Role of calcium carbonate precipitation in lake metabolism

“…Concentrations of metabolically important nutrients such as iron and phosphorus, are markedly low in hard-water lakes; however organic and inorganic nitrogen may occur at high levels (Manny, 1971). Indirect evidence would indicate (Schelske, 1962) that the low levels of naturally occurring chelating agents e.g.…”