Effects of Acid Rain on Sensitive Forest and Freshwater Ecosystems: Is the Problem Solved? By Charles Driscoll Syracuse University

Acid rain sources and background Effects of acidic deposition on forest ecosystems Effects of acidic deposition on aquatic ecosystems Recovery? Final thoughts

Sulfate Deposition 1994 vs 2010 1994 Sulfate ion wet deposition 2010 Sulfate ion wet deposition

Nitrate Deposition 1994 vs 2010 1994 Nitrate wet deposition 2010 Nitrate wet deposition

Ammonium Deposition 1994 vs 2010 1994 Ammonium wet deposition 2010 Ammonium wet deposition

Precipitation at Huntington Forest, NY 75 SO 4 ( eq/l) 50 25 0 30 NO 3 ( eq/l) 20 10 200 NH 4 ( eq/l) 15 10 5 ANC calc ( eq/l) 0-10 -20-30 -40-50 -60-70 1980 1985 1990 1995 2000 2005 2010 1980 1985 1990 1995 2000 2005 2010 Date

Concentration (µmo/l) 70 60 50 40 30 20 10 A. Sulfate and SO 2 R 2 =0.72 0 B. Nitrate and NO x Concentration (µmo/l) 30 20 10 R 2 =0.68 0 0 10 20 30 Airshed Emissions (Tg/yr)

Acid Neutralizing Capacity (ANC) Ability of a water to neutralize strong acid Titration by strong acid (ANC G ) ANC = base cations strong acid anions ANC calc = C B - C A Concern Acute Severe Elevated Moderate Low ANC (μeq/l) <0 0-20 20-50 50-100 >100 Effects Chronic Chronic and episodic Episodic Moderate episodic Limited

SO 4 2- DOC NO 3 - Al Acid Deposition SO 4 2- NO 3 - H + SO 2- ANC 4, NO 3-, DOC, H + Ca 2+ H + SO SO 2-2- 4 SO 2-4, NO 2-4,,, NO 3-, 3-3- Al, 3-,,, DOC, DOC, H +, H Ca, + H + ANC Al ANC SO 2- DOC SO 4, 2- NO 4 3-, DOC, NOH - +, ANC, 3 Al Ca 2+, Al

Sensitive lake types include perched seepage lakes and thin till drainage lakes Medium till drainage lakes show episodic acidification

Biogeochemical Studies Experimental Manipulations Gradient (spatial) studies Isotopes Modeling Paleoecology Time-series observations

Ecosystem Effects

Soil Acid Rain Effects Soil sulfur and nitrogen enrichment Nutrient cation (calcium, magnesium) depletion Aluminum leaching

Cumulative Frequency Diagram for Ca (cmol c /Kg) Ca Normalized to C (Oa Horizon) Cumulative Frequency Diagram for Exch. Al (cmol c /Kg) Exch. Al Normalized to C (Oa Horizon) % Less than thab Ca Ca 100 80 60 40 20 1984 2001 % Less than Exch. Acidity 100 80 60 40 20 1984 2001 0 0 20 40 60 80 100 120 140 0 0 20 40 60 80 Ca (cmolc/kg) Exchangeable Aluminum (cmolc/kg)

Hawley et al., UVM

Ring-Width Increment (mm) Adirondack Sugar Maple Growth Trends 3.5 3.0 2.5 2.0 1.5 1.0 0.5 Pre 1850 (n = 6) 1850-1899 (n = 18) 1900-1938 (n = 9) 0.0 1750 1800 1850 1900 1950 2000

Thomas, RQ, CD Canham, KC Weathers, and CL Goodale. 2010. Nitrogen deposition increases carbon storage in temperate forest trees, but responses vary by species. Nature Geoscience.

Aquatic Effects

Summary (n=1469) No. of Lakes (%) Surface area (ha) (%) ph < 5.0 352 24 2,000 8.4 ANC < 0 µeq/l 388 26 2,650 11 ANC 0-50 µeq/l 350 24 5,212 21

PnET Water balance Photosynthesis Living biomass Litterfall Wet Deposition Dry Deposition Climatic data Solar radiation Precipitation Temperature Net Mineralization Uptake BGC Aqueous reactions Surface reactions Cation exchange Adsorption Humic binding Aluminum dissolution/precipitation Weathering Deep water flow BGC Surface water Aqueous reactions

g S/m 2 -yr 2.5 2.0 1.5 1.0 Total Sulfate Deposition Base Case Moderate Controls Aggressive Controls 0.5 0.0 1850 1900 1950 2000 2050 2100 1.0 0.8 Total Nitrate Deposition g N/m 2 -yr 0.6 0.4 0.2 0.0 1850 1900 1950 2000 2050 2100 Year

Indian Lake ueq/l 250 200 150 100 SO 4 2- Base Case Moderate Aggressive Measured 50 0 250 200 Ca 2+ + Mg 2+ ueq/l 150 100 50 0 40 ANC ueq/l 20 0-20 year vs ca+mg base year vs Ca+Mg observed year vs Ca+Mg mod year vs Ca+Mg agg 7 ph ph units 6 5 4 1850 1900 1950 2000 2050 2100 Year

Model simulated median concentrations for lake chemistry and soil % BS at the 44 EMAP sites for pre-industrial time and current measured values, expressed as ueq/l, except ph and %BS. Pre-industrial conditions (1850) Current conditions (1990) SO 2-4 15.9 88.8 NO - 3 3.8 20.0 ANC 67.7 27.8 ph 6.63 5.95 Soil %BS 12.3 7.9

P2 P1

East Bear Brook Reference West Bear Brook Treated

West Bear Treatments Initiated Nov, 1989 1800 eq ha -1 yr -1 (NH 4 ) 2 SO 4 = 25.2 and 28.8 kg ha -1 yr -1 N and S Added in 6 bi-mo. applications

Time Series for BBWM NO 3 Export NO3 (eq ha -1 yr -1 ) 800 700 600 500 400 300 200 100 0 Calibration Treatments Begin Adapted from Fernandez et al. (2010) 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 East Bear Stream West Bear Stream 2006 2007

Mg ( eq L -1 ) 50 40 30 20 10 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 1989 1991 1993 1995 1997 1999 2001 1990 2008 2003 1992 2005 1994 2009 2008 1996 1998 2000 2002 2004 2006 2007 2006 40 60 80 100 120 140 Ca ( eq L -1 ) 2000 2002 2004 1990 1992 1994 1996 1998 East Bear (Reference) West Bear (1989-1995) 2009 West Bear (1996-2009) Updated from Fernandez et al. (2003)

Effects on Aquatic Biota Single organisms (condition factor, physiological effects) Population effects (increased mortality, eggs and fry most sensitive) Community effects (decreases in species richness)

Ecological Consequences are Clearest for Fish Acid kills fish directly: low ph poisons fish. Acid kills fish indirectly: low ph releases aluminum from soils to lakes and streams; aluminum poisons fish. Acid/Aluminum eliminate the most sensitive species first, lowering biodiversity. Very acid lakes are fishless.

Elevated Severe Moderate Number Fish Species 14 12 10 8 6 4 2 0-2 Acute Low -4-200 -100 0 100 200 300 400 500 ANC(ueq/L)

200 Big Moose Lake SO 4 2- ( eq/l) 150 100 50 NO 3 - ( eq/l) 1000 80 60 40 20 40 ANC ( eq/l) 20 0-20 -40 6 ph 5 4 Aluminum ( mol/l) 20 Ali Alo 10 8000 DOC ( mol C/L) 600 400 200 0 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011 Time

SO 4 2- Min - Mean - Max # sig Increase 0 # sig Decrease 48 NO 3-0 28 SO 4 2- +NO 3-0 48 C B 1 40 ANC calc 41 0 ANC 39 0 Ali 0 44-6 -4-2 0 2 4 Change ( eq/l)

Min - Mean - Max DOC -15-10 -5 0 5 10 15 20 Change ( mol/l-yr) 27 Increasing 6 Decreasing

20 DOC ( mol/l-yr) 10 0-10 Y= -1.9X - 2.58 r 2 = 0.17 Carbonate and Thick Till Medium Till Thin Till Seepage -6-5 -4-3 -2-1 0 C A ( eq/l-yr)

Why care about increases in DOC Increased light attenuation and thermal stratification (Effler et al. 1985) Increased trace metal (Hg) and nutrient transport (Dittman et al. 2010) Important energy source for Adirondack aquatic food chains? (Adams et al. 2009) Increases in supply of organic acids

ANC G ( eq/l-yr) 2.5 2.0 1.5 1.0 0.5 0.0-0.5-1 0 1 2 3 4 ANC calc ( eq/l-yr) 1:1 line Y = 0.43X + 0.18 r ² 0.54 Carbonate and Thick Till Medium Till Thin Till Seepage

ANC calc - ANC G ( eq/l-yr) 2.5 2.0 1.5 1.0 0.5 0.0-0.5 Carbonate and Thick Till Medium Till Thin Till Seepage -10 0 10 20 DOC ( mol/l-yr) Y= 0.07X + 0.52 r ² 0.44

Fish Population Changes (n=42) Period of Study All lakes Median* Mean* Maximum* 1984-1987 1995-2005 141 3 3.36 10 169 4 4.02 12 Change +28 +1 < 1 +2 *per lake

14 Number Fish Species 12 10 8 6 4 2 0-2 -4-200 -100 0 100 200 300 400 500 ANC (ueq/l)

Acidification Recovery Deposition Forests Lakes Soil Sugar Maple Sulfate Nitrate Acidity Calcium Red Spruce Sulfate Nitrate ANC DOC Fish??? Strongly Recovering Moderately Recovering Uncertain Deteriorating

Policy or Proposal NO x (million short tons) SO 2 (million short tons) Deadline for Implementation 4 Pollutant? 1990 Clean Air Act (Title IV) 4.6 8.9 2010 No NOx Budget Trading Program 60% summer reduction from 2000 levels N/A 2003 No Total US: 2.5 by 2010 2.2 by 2015 Total US: 4.16 by 2010 3.5 by 2015 Clean Air Interstate Rule (CAIR) Affected region: 1.6 by 2010 Affected region: 3.9 by 2010 2010 and 2015 No 1.3 by 2015 2.7 by 2015 60% reduction in NO x from 2003 levels 70% reduction in SO 2 from 2003 levels

Key Messages Air quality management in the U.S. has shifted from a local scale, command and control to a national, market-based approach Control programs have resulted in decreases in SO 2 and NO x emissions largely from electric utilities. Acid-sensitive forest and aquatic ecosystems have been impacted by acidic deposition. Emission controls have decreased surface water acidification, while soil acidification continues Future ecosystem recovery from acidic deposition will be slow; critical loads may help to guide air quality management. A diverse approach has facilitated a quantitative understanding of the effects of acidic deposition on ecosystems.

Carl Heilman

Changes in Fish in Adirondack Lakes (n=42) Category n Median ph Volume (10 4 m 3 ) Species Richness 1984-87 1994-2005 No fish 9 4.7 4.6 46 0 0 0 No change 7 5.1-5.3 100 1.7 1.7 0 Only gained 14 5.5-5.7 198 4.3 6.2 +1.9 Only lost 4 6.3-6.3 56 3.0 1.75-1.25 Gained and lost 8 6.2-6.5 350 7.1 7.9 +0.9