WESTERN MOUNTAINS AT RISK: WHEN DO WE KNOW ENOUGH TO LIMIT EMISSIONS?

OVERVIEW –Nitrate –Snow: Process-level controls –Flowpaths –Dissolved organic nitrogen (DON) –DIN and DON story –Telluride case study

PROBLEM: N DEPOSITION INCREASES

STRATEGIES FOR BRINGING INDUSTRY AND TREE- HUGGERS TOGETHER Process-level understanding of the N cycle Indicators of ecosystem N-status Management help

ABER SPAGHETTI DIAGRAM

Alpine areas: early warning indicators Organisms on edge of environmental tolerance Same processes as downstream forested and grassland ecosystems Less capacity! Less “buffering” Snow: moderates soil temperature, stores water and chemical, released at once

NIWOT RIDGE NADP

STREAM WATER RESPONSE GL4-220 ha

ACIDIFICATION Navajo-42 ha

Long Term Changes GL4-sediment profile: McKnight group

NUTRIENT ENRICHMENT PRISTINE LAKE

NUTRIENT ENRICHMENT ENHANCES Hg IN LAKES

NITRATE SUMMARY Atmospheric deposition of inorganic N is increasing Nitrate concentrations in surface waters during growing season increasing C:N ratio in sediments decreasing C:N ration decreases correlated with Hg Should we set critical loads for N dep?

CRITICAL LOADS 5-7 kg/ha-yr Episodic vs chronic Ecological Applications: 3-5 kg/ha-yr Reviews wanted only one value Williams and Tonnessen, 2000

CRITICAL LOADS 5-7 kg/ha-yr Episodic vs chronic Ecological Applications: 3-5 kg/ha-yr Reviews wanted only one value 4 kg/ha-yr

WHAT IS THE SOURCE OF NITRATE IN STREAMS? FLOWPATHS AND SOURCE WATERS

Martinelli Catchment

Stream Flow Chemistry (1)

 18 O in Snowpack, Snowmelt and Stream Flow

New Water and Old Water Using  18 O (1) New water by snowmelt  18 O & old water by base flow; Time series of snowmelt  18 O used.

New Water and Old Water Using  18 O (2) New water by snowmelt  18 O & old water by base flow; Median of snowmelt  18 O used.

Mixing Diagram: Paired Tracers

Flowpaths: TMM Burns et al nomenclature

Mixing Diagram: U-Space Defined by 8 Tracers

Flowpaths: EMMA

Prediction of Nitrate in Stream: Martinelli

Prediction of Nitrate in Stream: GL4

Nitrate  18 O

Sources of Nitrate: Martinelli

Sources of Nitrate: Green Lake 4

FLOWPATH SUMMARY 4 parts per mil separation in the delta O18 values of snowmelt (Taylor et al., 2002) Baseflow 35% of annual Q at 220 ha Ionic pulse somewhat important EMMA only works if we use talus: –Geographic areas as important as riparian areas for both water quantity and quality

Dissolved Organic Nitrogen in a Headwater Catchment, Colorado Front Range Eran Hood, Mark Williams, and Diane McKnightEran Hood, Mark Williams, and Diane McKnight INSTAAR and Dept. of GeographyINSTAAR and Dept. of Geography University of Colorado, BoulderUniversity of Colorado, Boulder

DON in Headwater Catchments N loss from terrestrial systems - “Leaky Faucet Hypothesis”N loss from terrestrial systems - “Leaky Faucet Hypothesis” Source of N for plants and aquatic biotaSource of N for plants and aquatic biota Affected by inorganic N deposition?Affected by inorganic N deposition?

APPROACH Nitrogen cycling in Alpine/Subalpine ecosystemNitrogen cycling in Alpine/Subalpine ecosystem –Characterize DOM: stable isotopes, 13C-NMR, elemental analysis, fractionation –Temporal and longitudinal changes in the character and source of DON –Ecological controls on DON

IMPORTANCE of DON µMoles/L

DON vs SOIL C:N

DON CONCENTRATIONS Discharge (m 3 /day) µMoles/L

METHODS FractionationFractionation –Chromatographic separation –Isolate hydrophobic acids (fulvic acids) from hydrophilic acids and low molecular weight compounds

Fulvic Acid (% of DOC) DOM Fractions: Seasonal trends

Red = non-humic green = fulvic Seasonal and longitudinal changes

DOM fractions: 13C Isotopes  13 C C:N Ratio

DOM fractions: 15N Isotopes C:N Ratio  15 N

DOM Fractions: Aromatic carbon C:N Ratio Aromatic C (%)

SUMMARY Most DON is non-humic Changes in DON quality linked to sources Effects of climate or environmental change

DOC Concentrations DOC (mg/L)

Percent Fulvic Acid % Fulvic Acid

METHODS FluorescenceFluorescence –All humic substances fluoresce –At least 2 main fluorophores –Provides information on precursor organic material of fulvic acids Excitation emission matrices (EEMS) different for microbial vs terrestrial DOCExcitation emission matrices (EEMS) different for microbial vs terrestrial DOC

METHODS Fluorescence IndexFluorescence Index –Simple interpretive tool –Ratio of 450 /500 nm emission at 370 nm excitation Fluorescence Index

MaySample May Sample JulySample July Sample SeptemberSample September Sample Fluorescence Index

SUMMARY FractionationFractionation –Recalcitrant DOM during snowmelt –Labile DOM in fall FluorescenceFluorescence –Source of source of dissolved organic material –Terrestrial source during snowmelt –Aquatic source in fall Insight into ecological controls on DOMInsight into ecological controls on DOM

THE DIN AND DON STORY: RATIO OF DIN TO DON IN ANNUAL RIVERINE FLUX Mark Williams, Eran Hood And Bill McDowell LTER X-site comparison

HYPOTHESIS DON export not related to N input Nitrate export responds to N input DON: DIN ratio thus an indicator of ecosystem N status Do not need long-term data sets

LEAKY FAUCET Persistent “leak” of DON from catchments DON is decoupled from microbial demand for N. DON export coupled to soil standing stock of C, N Lag between N inputs and DON export

FORESTED CATCHMENTS

MORE FORESTED CATCHMENTS

DIN: DON for ALPINE CATCHMENTS

FORESTED/ALPINE COMPARISON

DIN and DON: SUMMARY May be an indicator of ecosystem N status May provide an emotionally neutral starting point for regulating emissions and other N sources Looking for more data sets!

TELLURIDE: New West

LEGACY OF EXTRACTIVE INDUSTRIES

TROPHY HOMES: A NEW ERA

HOW TO PROTECT? Balance restrictions with reasonable economic and recreational activities Legal approach that is bulletproof –Good intentions not good enough Committed stakeholders Community consensus

INITIAL EFFORTS San Miguel Planning Department proposed “blue line” at 11,000’ Developers said they would sue County attorney refused to back planning department “Blue line” was capricious and arbitrary Needed a new strategy

WATER QUALITY Mom and apple pie-no one against good water quality Streams are kidneys of an ecosystem Water quality provides diagnostic indicator of ecosystem health Indicators based on process-level research

LAND USE CODES Maximum building footprint of 800 sq ft No septic tanks No fertilization Maximum road width of 10 feet No winter plowing

3 June 1998 Land use code amendments adopted by the Board of County Commissioners We could not pass those codes today; new BOCC