Measurement of Wet Deposition of Inorganic and Organic Nitrogen in a Forest Environment
Abstract
Nitrogen is often the limiting nutrient for tree growth. Wet deposition is a major source of nitrogen to a forest. Few previous studies have included organic nitrogen as part of the assessment of atmospheric inputs of nitrogen to forest ecosystems. A significant fraction of wet and dry deposited nitrogen is organic, and several studies have shown that organic nitrogen can thermally or photochemically degrade into inorganic nitrogen as well as be directly taken up by leaves, thereby making it a viable source of nitrogen to forests. Our hypothesis is that organic nitrogen is a significant fraction of nitrogen deposited via wet deposition to a forest, and that this nitrogen can be utilized by the trees. Dissolved inorganic and organic nitrogen were measured in precipitation at the University of Michigan Biological Station (UMBS) in an open field and under the forest canopy. Precipitation was collected on an event basis. The rainwater collectors were deployed just prior to a rain event and were retrieved immediately after the rain finished. The collection bottles were surrounded with dry ice to freeze the precipitation upon collection, preventing degradation of any nitrogen species either by bacteria or by chemical reactions. The samples were analyzed for nitrate, ammonium, and organic nitrogen content. The results of the frozen, single event sampling were compared with samples collected unfrozen over a one-week period in order to investigate sample stability issues. Canopy retention of nitrogen in precipitation will also be discussed.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2004
- Bibcode:
- 2004AGUFM.B13B0227H
- Keywords:
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- 1806 Chemistry of fresh water;
- 1610 Atmosphere (0315;
- 0325);
- 1615 Biogeochemical processes (4805);
- 0315 Biosphere/atmosphere interactions;
- 0345 Pollution: urban and regional (0305)