1 Nitrogen in the Environment David Gay 1 & Bob Hall 2 1 NADP Program Office, (217) U.S. Environmental Protection Agency, Region 9, San Francisco, CA

2 Nitrogen is Good….. right? N 14

3 -Nitrogen is considered a ‘limiting nutrient’ -plant growth -animal growth (in bodies and waste) -78% of the Atmosphere Nitrogen is Essential and Everywhere

4 But Nitrogen is also a Pollutant -Adverse effects on health and the environment

5 Topics To Discuss How & Why is N a pollutant? Where does Nitrogen Pollution come from? Other impacts?

6 How and Why is Nitrogen a Pollutant? Nitrogen is limited Adding N is adding “fertilizer” Makes things grow (algal blooms, red tide, etc.) These live thinks die, and consume oxygen O2 breathing life then die

7 Add Nitrogen to lake or Ocean…

8 Eutrophication is the term used to describe these responses to nutrient (N) over-enrichment

9 Eutrophication can lead to Hypoxia Hypoxia = ‘low oxygen’ HOW? 1.Nitrogen (fertilizer) added 2.High growth rates 3.Population crashes 4.Decomposition consumes oxygen 5.Low oxygen 6.Fish kills, dead zones

10 Dead Zones Red = high N fertilizers

11 Add Nitrogen to the Atmosphere? All nitrogen is ultimately oxidized (N 2 ?) Result HNO 3 (Nitric Acid) “Acid Rain, snow and fog” NO 2 + OH ∙ + M ↔ HNO 3 + M HNO 3 + H 2 O ↔ H + + NO 3 -

12 Results of Acid Precipitation Mt. Mitchell, North Carolina

13 You also get Smog…..

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15 Nitrogen to Groundwater? Organic nitrogen Nitrates ammonia

16 So……… Where does Nitrogen Pollution Come From?

17 Nitrogen comes in Lots of Forms Nitrogen gas CompoundReactivityMobilityMisc. Chemical Formula N2N2 Not veryVery NitrateNO 3 ModeratelyVery Organic Nlotsdepends Fertilizer, combustion, explosives Example: Urea Ammonia (gas) NH 3 VeryModeratelyProduct of HB, Fert

18 Nitrogen is Moving Around the Environment Denitrification in Soil –Bacteria change NO3 in the soil to atmospheric N2. Volatilization from Soil –urea fertilizers and manures on the soil surface converts to atmospheric NH3. Runoff over Soil –Carries the N fertilizers and manure into rivers and streams; water quality concerns. Leaching from Soil –Carries NO3s down past where plants can use, into groundwater

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20 Nitrogen Cycle

21 Sources of Nitrogen to the Atmosphere Burning (oxidized nitrogen, particularly) Animals (ammonia)

22 Hog Production in USA (1 dot= 10,000 Hogs and Pigs)

23 Cows and Pigs and Chickens and Sheep and Goats and etc. etc. etc.

24 Sources to the Atmosphere: NOx Fossil fuel combustion: 40-58% Soils: 13-20% Lightning: 8-17% Biomass burning: 12-17% Photo-chemical oxidation: 5-8% Aircraft: 1% Transport through stratosphere: %

25 Agricultural: 49-63% CAFO Fertilizer: 11-12% Oceanic emissions: 10-13% Soil emissions: 10-13% Biomass burning: 4-7% Human excrement: 5-8% Coal combustion and automobiles:3-4% Holland et al., Ecological Applications 15(1): 2005, pp Sources to the Atmosphere: NH3

26 Natural Sources Lightning Soil bacteria Algae Uncultivated legumes Total = 140 mil. M.tons

27 Fertilizers Soil bacteria fix atmospheric nitrogen –N2 gas to reactive forms in the soil) Haber Process (fertilizer production) is the same thing; –artificial nitrogen fixation

28 The Fate of Reactive Nitrogen N Fertilizer Produced N Fertilizer Applied N in Crop N In Feed N in Store N Consumed Only 4% of the reative N produced in the Haber-Bosch process and used for animal production enters the human mouth. Galloway JN and Cowling EB Galloway 2002 The rest ( 96%) escapes into air, soil, surface water (rivers, streams) and groundwater (aquifers) and cascades towards the oceans

29 Source: 2 nd International Nitrogen Conference Nitrogen Use and Emission is UP UP UP

30 Deposition Is Also Increasing (N into Ecosystems)

31 Inorganic Nitrogen Wet Deposition, 2007

32 Nitrogen Deposition Past and Present Galloway and Cowling, 2002; Galloway et al., 2002b mg N/m 2 /yr -Change in Northern Hemisphere – Fossil fuels (industrial revolution), and ag -Change in Southern Hemisphere – Slash and burn

33 Nitrate Deposition Trends 3-year running average 1985 – 2008

34 Animation

35 INCREASING Trend DECREASING Trend Number of Sites Number Significant Number of SitesNumber Significant Nitrate Trend in Precipitation Trends Emissions Concentration -37% -22%

36 Ammonium Deposition Trends 3-year running average 1985 – 2008

37 Animation

38 Nitrogen in the Environment David Gay 1 & Bob Hall 2 1 NADP Program Office, (217) U.S. Environmental Protection Agency, Region 9, San Francisco, CA