Assessing soil carbon storage and climate change mitigation in biosolids mine reclamation projects
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Click to add organizations Assessing Soil Carbon Storage and Climate Change Mitigation in Biosolids Mine Reclamation Projects Presented By: Andrew Trlica, MSc SYLVIS, New Westminster, BC
Transcript of Assessing soil carbon storage and climate change mitigation in biosolids mine reclamation projects
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Assessing Soil Carbon Storage and Climate Change Mitigation in Biosolids Mine Reclamation Projects
Presented By: Andrew Trlica, MScSYLVIS, New Westminster, BC
Biosolids and their use in reclamation
Carbon accounting and mine reclamation
Research results: Soil carbon storage in mine reclamation
Life cycle assessment of biosolids in mine reclamation
Conclusions and opportunities
Outline
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The treated, stabilizedsemi-solid product ofwastewater treatment process
Municipal wastewater Pulp and paper wastewater
Contain:• Organic matter (>50%)• Nutrients (0.1%-10%)• Trace element content
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What is biosolids?
Mining disturbance often makes for poor soil Low organic matter Nutrient poor, slow cycling
pH too high/low Too compact, poor rooting, extreme texture
Elevated trace constituents
Plant productivity very low
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Challenges to Mine Reclamation
Practiced for over forty years worldwide Coal mines Aggregate pits Mineral tailings Waste rock dumps
Well-researched Well-understood
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Biosolids and Mine Reclamation
Addresses many reclamation challenges Increased organic matter and plant nutrients
Lower bulk density Mitigate metals contamination
Modulate pH (ARD) Augment soil microbial community
Better plant establishment & growth
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Biosolids and Mine Reclamation
Climate change = too much C in atmosphere
3x more C in soil and plants than atmosphere
1% per year added to atmospheric C from fossil fuels
10x as much atmospheric C cycles through land per year
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Global Carbon Cycle
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Land Disturbance and C Release
Source data: Lal, R. (2004). Science 304:1623-1627.
Terrestrial C
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Reduced/No-till farming, Alberta Emissions Offset Registry
Improved forestry practices, BC Pacific Carbon Trust
Afforestation – Clean Development Mechanism (Kyoto)
Emission Offsets with Land-based C
Source: USDA Natural Resource Conservation Service, Missouri, http://www.mo.nrcs.usda.gov/news/MOphotogallery/Crops-Cover%20Crops/no-till1.jpg
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Biosolids increase plant productivity Biosolids are rich in organic C Do mine soils reclaimed with biosolids store more
carbon? Is this storage “long-term”? Climate change implications of enhanced C storage?
Biosolids, Mine Reclamation, C Storage
Mine areas contained biosolids and “conventional” reclamation areas; samples compared soil C storage
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Field Study
Courtesy of Google Maps, 2010
Location Mine type Years since reclamationCentralia, WA Coal 17Sechelt, BC Sand & Gravel 9Logan Lake, BC Copper/Moly 8RMI, Mass. & NH Sand & Gravel 7Pennsylvania Coal 27
Mean 32.5 ± 3.2 t C/ha increase in biosolids sites over conventional in top 15 cm
Older sites remained higher in C
No significant difference in 15-30 cm
Relative increase depended on local site factors
Estimate 0.5-1.0 t C/ha/yr increase over 20-30 yrs
Equal to ~$800/ha or $12-25/ha/yr if traded on PCT
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Research Results
What are the “real” net reductions in GHG when biosolids are used for reclamation?
Relevant to land-based C offset creation – usually involve aspects of LCA to determine offset amount (“Business As Usual” vs. Biosolids)
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GHG Life Cycle Assessment
LCA tracks inputs and emissions to environment from doing/making something
More complete view of net “consequences” of a process or decision
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GHG Life Cycle Assessment
Source: Forest Ecosystem Ecology Lab, U. of Wisconsin-Madison, http://carbonmodel.org/lca/
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Based on biosolids management and land use in Puget Sound region of Washington state
Compares GHG emissions in two scenarios: Conventional reclamation + biosolids sent to dryland wheat fields
Biosolids in reclamation + NPK fertilizer to wheat fields
Tracks all major emissions sources/sinks, eg. fuel use in trucks, soil N2O, tree growth rate, manufactured inputs, etc.
Life Cycle Assessment of Biosolids in Mine Reclamation
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Life Cycle Assessment of Biosolids in Mine Reclamation
Net GHG “sink” for both scenarios
However, biosolids resulted in larger sink.
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Life Cycle Assessment: Results
Scenario Net GWP (t CO2-eq.)Conventional Reclamation -477Biosolids Reclamation -539
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Greater net sink of GHG using biosolids for reclamation
Main advantage is greater soil and biomass C storage
Suggests that using biosolids in mine reclamation may result in lower net GHG emissions than Business As Usual
Life Cycle Assessment: Results
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Biosolids can be used to alleviate several reclamation challenges
C storage is another benefit of biosolids use in mine reclamation
Demonstrates relative permanence of C storage – very important from offset perspective
Mine closure can have positive GHG/climate change mitigation effect
Biosolids amendment may enhance this effect
Conclusions
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Better GHG quantification before/after closure
Develop greater diversity of land-based C protocols for offset and $$$ creation
Mine closure active participant and contributor to offsets market
If projects generate offsets, could lower reclamation costs overall.
Next Steps
