260 likes | 277 Views
Effects of Watershed Acidification on Soil Water and Stream Water Chemistry. H 2 SO 4. HNO 3. Soil Surface. SO 4 2- + H +. H + + NO 3 -. H 2 SO 4. HNO 3. Soil Surface. SO 4 2- + H +. H + + NO 3 -. Soil Charge. H 2 SO 4. HNO 3. Soil Surface. SO 4 2- + H +.
E N D
Effects of Watershed Acidification on Soil Water and Stream Water Chemistry
H2SO4 HNO3 Soil Surface SO42- + H+ H+ + NO3-
H2SO4 HNO3 Soil Surface SO42- + H+ H+ + NO3- Soil Charge
H2SO4 HNO3 Soil Surface SO42- + H+ H+ + NO3- Mobile Anion Theory
H2SO4 HNO3 Soil Surface SO42- + H+ H+ + NO3- Cation exchange SO42- + cations NO3- + cations
2H+ 2H+ H+ Ca2+ Mg2+ K+ Ca2+ Mg2+ K+ H+ H+ H+ H+ H+
CaSO4 or Ca(NO3)2 MgSO4 or Mg(NO3)2 K2SO4 or KNO3 leach through soil Base cations in solution pair with mobile anions in solution Ca2+ Mg2+ K+ SO42- or NO3- SO42- or NO3- SO42- or NO3- H+ H+ H+ H+ H+
H2SO4 HNO3 Soil Surface SO42- + H+ H+ + NO3- SO42- + cations NO3- + cations Leaches from soil Leaches from soil
H2SO4 HNO3 Soil Surface SO42- + H+ H+ + NO3- Acidifies soil and dissolves soil Al3+
3H+ 3H+ 3H+ Al3+ Al3+ Al3+ Al3+ Al3+ Al3+ H+ H+ H+ H+ H+ H+ H+ H+ H+ Al Dissolution and Exchange
leach through soil Al2(SO4)3 or Al(NO3)3 Al3+ Al3+ Al3+ SO42- or NO3- SO42- or NO3- SO42- or NO3- H+ H+ H+ H+ H+ H+ H+ H+ H+
H2SO4 HNO3 Soil Surface SO42- + H+ H+ + NO3- Acidifies soil and dissolves soil Al3+ SO42- + Al3+ NO3- + Al3+ leached to streams & lakes Al3+ is toxic to aquatic organisms Soluble Al3+ interferes with plant root functions Al3+ can reduce plant vigor and growth
Process Summary • Mobile/excess anions control base cation and acid cation leaching • Base cation leaching = loss of soil base cations/nutrients/fertility • Acid cation leaching results in acidification of soil water and stream water
Sulfate Deposition across the NE • Some of the highest rates in the country • Orographic uplifting and high elevation ridges • Primary sources – Ohio River Valley
Soil Chemistry Monitoring Program Objective: Gather baseline soil chemistry data across the forest for multiple soil types across multiple geologies • Accomplished through a state wide partnership with NRCS Soil Survey Division, West Virginia University, and USFS • Over 400 soil pedons characterized in the state • 2006 Forest Plan requires monitoring of sensitive areas for the purpose of conducting management activities • Wilderness Areas • Class 1 Air Monitoring Program • Academia
Acid Deposition Sensitivity Map • Soil Forming Factors • PARENT MATERIAL • GEOLOGY • WEATHERING RATES • Based on geochemistry • Compared against 303d impaired stream list for acid rain effects • Soils used to ground truth map in sensitive watersheds
Resource Effects - Acid Deposition Water Chemistry & Watershed Sensitivity on the Monongahela NF
Non-Management Effects • Effects may include: • Decreasing stream pH, ANC, increasing metal concentrations • Declining fish populations and species • Base cation losses in the soil • Foliar macronutrient imbalances • Shifts in biodiversity in the understory vegetation
Resource EffectsAcid Deposition WATER • Effects may include: • Changes in Stream chemistry -decreases in Stream pH and ANC • High Levels of Iron and Aluminum • Nitrogen and Sulfate Leaching from Watershed Soils • Ultimately, losses or Shifts in Stream Biota Populations
Soil Chemistry Monitoring Program • Objective: Gather baseline soil chemistry data • Forest Wide • Watershed Assessments • NRCS data collection for soil survey updates • Project Specific • Soil Disturbing activities • Wilderness Areas • Class 1 Air Monitoring Program • Academia • Archive Soil Samples
High Moderate Low Alluvium Anthony Creek Watershed 2007 Sampling
Criteria Used to Assess Risk • Soil Chemistry • Ca:Al Ratios (SrCl2 Extraction Method; Penn State University Lab) • Base Saturation • Effective Cation Exchange Capacity (ECEC) • Stream Chemistry • Foliar Indicators • Air Quality
Mitigations • Long harvest rotations 100 years • No whole tree harvesting; leave tops and limbs • Avoid harvesting in areas with shallow soils • Minimize soil disturbance • Prescribe fire? • Chemical additions ?
Liming • Why? • Has this been done before? • Cost Efficient? • Effects • Pros and Cons
Stream Liming Cherry River Watershed Lime Dump Cranberry River Watershed Liming Drum Station
Effects to the Soil from Liming • Pulses of nitrate and sulfate leaching in the months post application • pH does not readily increase in mineral (A, E, and B) horizons • Response held to the O, A, and possibly transition horizons (AE, AB, BA, etc.) • [Al] and [Mn] decrease, [Ca] and [Mg] increase in soils