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Constructing Soil: The Key Element for Sequestering Lead and Carbon


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6th National Cultivating Community Composting Forum
Panel 2: It's All About the Soil
Sara Perl Egendorf
The Graduate Center of the City University of New York, PhD Candidate

Published in: Environment
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Constructing Soil: The Key Element for Sequestering Lead and Carbon

  1. 1. Constructing Soil: The Key Element for Sequestering Lead and Carbon 6th National Cultivating Community Composting Forum Sara Perl Egendorf May 13, 2019
  2. 2. Presentation Outline: • Lead (Pb) in Urban Soil • What can we do about it? • Carbon (C) Sequestration • What is it? How does it work? • Constructing Soil in NYC • Carbon Sponge + JUST SOIL • Legacy Lead • Connecting Across Time and Space
  3. 3. Problem: Urban Soils are Highly Contaminated with Lead (Pb) - ~36% of NYC’s surface is covered with soil - No systematic map of NYC soil Pb has been created, but Pb concentrations above EPA standards (400 ppm) are common - Pb cannot be broken down or effectively removed from soil - Not just gardeners – but all urban residents are at risk for exposure – especially kids Cheng et al., (2015) Trace Metal Contamination in NYC Garden Soils
  4. 4. Solutions for Pb in Soil? Can we remove Pb from soil? (Can plants help us do this, a.k.a phytoextraction?) No, not safely Good news – crops are usually safe! (Just make sure to wash them) Can we add amendments to make Pb less toxic (bioavailable?) Yes, but this can be tricky Testing methods are disputed, phosphorus can make arsenic more available… but adding materials like compost is still good for soil Can we dig up and haul out soil? Yes, if money’s not a constraint Can we cover contaminated soil? Absolutely! So where do we get new soil? ?
  5. 5. Solution: NYC Clean Soil Bank (CSB) / PUREsoil NYC - Created CSB - Excavated sediments - Tested sediments through certified York Analytical Laboratory - Creates food scrap compost used for study - Compost was tested for contaminants prior to use - Manages NYC community gardens - Provided space, materials, and gardener outreach for study - Created experimental beds - Grew crops - Conducted soil and plant analyses - Conducted data analyses Sediments Community Gardens Experimental Design & Testing Compost
  6. 6. Solution: NYC Clean Soil Bank (CSB) - CSB sediments and compost mixtures create viable growing media - Soil parameters indicate mixtures are suitable for edible crops - More than 33% of this compost / sediment mixture was was adequate for yield - Crops show no evidence of contamination - Soil metal concentrations remained very low over initial two years, but monitoring will continue Egendorf et al., (2018) Constructed soils for promoting community gardening and mitigating lead (Pb) Exposure: the NYC Clean Soil Bank pilot study
  7. 7. ENYF 33% in 2018 E 43rd St 33% in 2018 What biological, chemical, and physical processes are going on in these newly constructed soils over time and in different spaces? How much carbon is being sequestered? How might we optimize those conditions?
  8. 8. What is Soil Carbon Sequestration? • Removal of atmospheric CO2 by plants • Storage of C as • soil organic matter (SOM) or soil organic carbon (SOC) Lehman and Kleber (2015). Then contentious nature of soil organic matter
  9. 9. How Does Soil Carbon Sequestration Occur? • Inputs: • Aggregation: • Stable micro-aggregates form through organo- mineral complexes that encapsulate C and protect it against microbial activities and decomposition. • Translocation into the sub-soil: • SOC moves into the sub- soil and away from the zone of disturbance by anthropogenic activities and erosional processes. Lal (2004) Carbon sequestration to mitigate climate change Schmidt et al. (2011) Persistence of SOM as an ecosystem property
  10. 10. • Outputs: • Decomposition and respiration • Mineralization and oxidation • Leaching and erosion • Historical SOC losses range from 40-90 Gt • SOC depletion is a reversible process How is Carbon Released from Soil? Rodale Institute (2009) The Nitrogen Cycle
  11. 11. Big Ideas on Soil Carbon Sequestration • C sequestration is dependent on environmental factors and soil structure • How do we manage and support soil aggregating conditions, particularly in the urban environment? • Increases in C storage occur quickly with C depleted sediments • We have a very large supply of subsoil / glacial sediments with the Clean Soil Bank (CSB) / PUREsoil NYC • What conditions optimize C increases over time?
  12. 12. What happens over time as we construct new soils?
  13. 13. Raves Garden Constructing Soil for Environmental and Social Justice Glacial Sediments Compost Researchers Youth Community Members from with Welcome to a JUST SOIL project
  14. 14. CSB Generating Site Jamaica, Queens 4/20/18 NY Hall of Science 4/20/18
  15. 15. NY Hall of Science 33% Compost Mixtures 4/24/18
  16. 16. NYCHA Ravenswood Seed Starting 5/7/18
  17. 17. NYCHA Ravenswood Bed Frame Building 5/14/18
  18. 18. Meso Scale: Legacy Lead Coalition 20+ organizations meet monthly since January, 2016 How can a coalition build and support: Clean Soil Distribution Network: Connecting composters, agencies, orgs Goal of creating multiple local hubs Gardener/grower distribution networks Critical Soil Education: Biogeosociochemical Pb cycle (comic) Revamped BMPs Connect with k-12 garden ed networks Soil Research: Current pilot studies Creating protocols for constructed soil research Platform for long-term multi site studies
  19. 19. Macro Scale: Connecting with Other Regions Mielke et al. (2011) Estimation of leaded (Pb) gasoline’s continuing material and health impacts on 90 US urbanized areas 100+ regions mapped for Soil Pb (US and abroad) Only 23 reported US soil Pb cover interventions (Laidlaw et al., 2017) Strengthen / Build Proximal / Distal Connections: Currently work with 9 cities Continue to map anthroposols / Constructed Technosols Local Partnerships: Framework for just interventions Build connections with growers / soil stewards Academic Resources: Compile data on soil creation Study local particularities
  20. 20. Collaborating Across Scales of Time and Space Time Space Carbon Sponge + JUST SOIL Legacy Lead Coalition New Soil Layer: Conscious Anthropocene Marker How can affected communities effectively construct soils to sequester lead and carbon? How can community and scientific partnerships further these efforts to reduce waste and contamination exposure, and promote environmental justice, food justice, and all the benefits of urban green space?How might we work together?
  21. 21. Constructing Soil: The Key Element for Sequestering Lead and Carbon 6th National Cultivating Community Composting Forum Sara Perl Egendorf May 13, 2019 Thank you for your attention! IG @just_soil / Twitter @justsoilnyc