Critical Load Development for Nitrogen and Sulfur Deposition Elizabeth Waddell

1. Critical Load Development for Nitrogen and Sulfur Deposition Elizabeth Waddell Air Resources Specialist Pacific West Region 206 220 4287 Elizabeth_waddell@nps.gov 1

2. Science Workshop • Funded by NWCAA • Co-sponsored by NWCAA, NPS, USFS, and USGS • Focus on NW WA but applicability for most of R10 2

3. Participants Researchers with expertise in nitrogen and sulfur effects on: • Lichens • Soil chemistry • Vegetation • Water chemistry • Mycorrhizae • Diatoms • Deposition monitoring • Deposition modeling • Setting critical loads 3

4. Participants • NPS Science Staff • USFS • NWCAA • PSCAA • Ecology • Tribes 4

5. What is a Critical Load? “the quantitative estimate of an exposure to one or more pollutants below which significant harmful effects on specified sensitive elements of the environment do not occur according to present knowledge.” 5

6. What is a Critical Load? N Deposition (kg/ ha /yr) Natural background N deposition Change in algal species Changes in tree and soil chemistry Change in alpine plant species Effects on aquatic and terrestrial biota (episodic or chronic acidification) Increased NO3 in lakes 6

7. Critical Loads in Action • Critical load work proceeding at Rocky Mountain NP • 1.5 kg N/ha/yr for eutrophication effects of alpine lakes • Current deposition is 3-4 kg N/ha/yr • Partnering with CDPHE to identify sources and reduce emissions http://www.cdphe.state.co.us/ap/rmnp.html 7

8. Current Knowledge – Deposition Monitoring • NADP Monitoring • S deposition – declining • N deposition – no trend • Between 1 and 2 kg/ha/yr • Does not include dry or occult deposition • All low elevation sites 8

9. Current Knowledge – NADP N Deposition Monitoring 9

10. Current Knowledge – N Deposition Monitoring Research • Throughfall Monitoring • Low under canopy • Lichens absorbing N? • High in bulk deposition • Inconsistent with NADP or CG • Snowfall • Comparable to NADP 10

11. Current Knowledge – Deposition Modeling Research WSU CMAQ preliminary work based on 36 km grid 11

12. Current Knowledge – Deposition Modeling Research • Modeling • Overpredicts dry • Underpredicts wet • No cloud • Limited sensitivity analysis 12

13. Current Knowledge – Ecological Effects Lichens • Sensitive to air pollution • N sensitive lichens absent in areas of “high” nitrogen deposition • Preliminary work with Columbia Gorge throughfall monitoring data yields a CL of 2.4 kg/ha/yr • 2.0 dry deposition • 0.4 wet deposition 13

14. Current Knowledge – Ecological Effects Acidification effects • Nutrient effects of N expected to occur at lower deposition rates than acidification effects • MAGIC model yielded an “upper bound” CL of 10 kg S/ha/yr for acidification of Lake Eunice (Mt. Rainier) • (Recent documentation of episodic acidification at Lake Eunice due to snowmelt pulse) 14

15. Research Priorities • Aquatic Ecosystems • Mine existing water quality databases to identify: • Areas which may already be affected by N or S deposition • Areas which may be sensitive to additional N • Establish CL for eutrophication of aquatic ecosystems using RMNP work as a model (diatoms) 15

16. Research Priorities • Terrestrial Ecosystems • Lichens • Collect lichens from NADP and “throughfall” sites; • Refine deposition modeling and/or conduct additional monitoring to better establish a deposition gradient and/or use PRISM • Natural Resources Conservation Service (NRCS) soils mapping effort • Identify sensitive areas (N and Al) 16

17. Research Priorities • Terrestrial Ecosystems • Alpine meadows • Fertilization effects research using RMNP as model • Mycorrhizal diversity • Similar to lichens in terms of PNW ecological importance and diversity. 17

18. Not a Research Priority • Quantifying actual deposition • Adequate to “index” to NADP or other standard monitor 18

19. Questions? 19