1. Nitrogen In Groundwater from Ground-Water Microbiology and Geochemistry By: Francis H. Chapelle Images are from Google searches and for visual effect only

2. The Nitrogen Cycle  Atmospheric Nitrogen (N 2 )  Microbially mediated nitrogen fixation, reduction, and oxidation  N 2 +6H+16ATP -->2NH 3 +16ADP+16P  N 2 -->NH 3 -->NO 2 - -->NO 3 - -->NH 2  Denitrification: NO 3 -->NO 2 -->N 2 O-->N 2  Atmospheric Nitrogen (N 2 )  Microbially mediated nitrogen fixation, reduction, and oxidation  N 2 +6H+16ATP -->2NH 3 +16ADP+16P  N 2 -->NH 3 -->NO 2 - -->NO 3 - -->NH 2  Denitrification: NO 3 -->NO 2 -->N 2 O-->N 2

3. Nitrogen Cycling in Ground- Water Systems  Energy availability limits nitrogen fixation  Nitrification occurs under aerobic conditions  Denitrification occurs under anaerobic conditions  Nitrate in Groundwater:  Blue baby syndrome  Gastric cancer rates  Nitrate Sources to Ground-water:  Animal excrement and manure  Sewage effluents  Nitrogen fertilizers  Municipal wastes  Naturally occurring nitrate sources  Energy availability limits nitrogen fixation  Nitrification occurs under aerobic conditions  Denitrification occurs under anaerobic conditions  Nitrate in Groundwater:  Blue baby syndrome  Gastric cancer rates  Nitrate Sources to Ground-water:  Animal excrement and manure  Sewage effluents  Nitrogen fertilizers  Municipal wastes  Naturally occurring nitrate sources

4. Animal Excrement and Manure

5. Sewage Effluents

6. Nitrogen Fertilizers

7. Municipal Wastes

8. Naturally occurring nitrate sources  15 N and 14 N isotopes   15 N ratios  15 N and 14 N isotopes   15 N ratios

9.  Why is it important to understand the nitrogen cycle when analyzing groundwater composition? What are some of the limiting factors of the nitrogen cycle within groundwater systems?