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  • Количество слайдов: 32

Reclamation of Degraded Land with Biosolids Impacts of final land use, Impacts of reclamation Reclamation of Degraded Land with Biosolids Impacts of final land use, Impacts of reclamation method

GHG Consequences of Reclamation • Final land use post-reclamation • Reclamation improvements with biosolids GHG Consequences of Reclamation • Final land use post-reclamation • Reclamation improvements with biosolids • Land- and biosolids use interact

Reclamation to forest • High gains to Soil and Biomass C • Conventional and Reclamation to forest • High gains to Soil and Biomass C • Conventional and residuals reclamation

Partial Reclamation + Development • Some soil/biomass C • But large GHG costs for Partial Reclamation + Development • Some soil/biomass C • But large GHG costs for construction and use over life cycle

Field study – Soil C in Reclamation • Soil C benefits of biosolids reclamation Field study – Soil C in Reclamation • Soil C benefits of biosolids reclamation • Compare similar conventional and biosolids sites up to 30 year post-reclamation

Results: Soil C sequestration Results: Soil C sequestration

Results: Soil C sequestration • Soil C increases with biosolids § +15 Mg ha-1 Results: Soil C sequestration • Soil C increases with biosolids § +15 Mg ha-1 (Centralia) § +38 Mg ha-1 (Highland Valley) • 0. 11– 1. 14 Mg CO 2 e per Mg biosolids

Results: Soil C sequestration • Increases and efficiency depend upon reclamation conditions and method Results: Soil C sequestration • Increases and efficiency depend upon reclamation conditions and method Centralia, 0. 11 Mg CO 2 e per tonne: Old sites, 1 m topsoil, very high biosolids rate Pennsylvania, 0. 55 Mg CO 2 e per tonne: Old sites, relatively good topsoil, moderate biosolids addition Highland Valley, 1. 03 Mg CO 2 e per tonne: No topsoil, very poor conventional recl. , low biosolids rate Sechelt 1. 14 Mg CO 2 e per tonne: Good response, poor topsoil moderate biosolids addition

Study conclusions • 55– 139 Mg CO 2 e ha-1 Soil C increase for Study conclusions • 55– 139 Mg CO 2 e ha-1 Soil C increase for using residuals • Increase was present even after 30 years • Specific changes related to site conditions and reclamation history • What about other GHG shifts with reclamation?

Land use • House or forest? § § § Soil C Biomass C Construction/use/maintenance Land use • House or forest? § § § Soil C Biomass C Construction/use/maintenance Operations: transport, soil N 2 O, fertilizer credit, etc. Competing biosolids uses

Life cycle assessment of reclamation • What is LCA? § Track all inputs/outputs/activi ties Life cycle assessment of reclamation • What is LCA? § Track all inputs/outputs/activi ties required § Assign environmental impact § Assess (relative) environmental consequences

Life cycle assessment of reclamation • Alternate post-reclamation land uses § Houses vs. forest Life cycle assessment of reclamation • Alternate post-reclamation land uses § Houses vs. forest § Reflects land-use pressures in Puget Sound

Life cycle assessment of reclamation • • 1 ha of degraded land Urban margin Life cycle assessment of reclamation • • 1 ha of degraded land Urban margin of Puget Sound region, WA 30 year timeline Houses or forest

Life cycle assessment of reclamation • “Choose your own adventure” • Natural cover (forest) Life cycle assessment of reclamation • “Choose your own adventure” • Natural cover (forest) § Biosolids reclamation § Conventional reclamation • Development

Reclamation – Soil Carbon • Conventional Reclamation: 110 Mg CO 2 e • Biosolids Reclamation – Soil Carbon • Conventional Reclamation: 110 Mg CO 2 e • Biosolids reclamation: 220 Mg CO 2 e • Based on C accumulation rate and Mg CO 2 e per tonne of biosolids

Reclamation – Biomass Carbon • PNW forests respond to biosolids (soil low in N) Reclamation – Biomass Carbon • PNW forests respond to biosolids (soil low in N) • Conventional: 183 Mg CO 2 e • Biosolids: 275 Mg CO 2 e

Conventional Reclamation • Reclamation to Doug Fir forest • 110 Mg CO 2 e Conventional Reclamation • Reclamation to Doug Fir forest • 110 Mg CO 2 e soil C • 183 Mg CO 2 e biomass C • 393 Mg CO 2 e per ha total

Biosolids reclamation • • • Reclamation to D. Fir 220 Mg CO 2 e Biosolids reclamation • • • Reclamation to D. Fir 220 Mg CO 2 e soil C 275 Mg CO 2 e biomass C 18 Mg CO 2 e N applied as N 2 O 477 Mg CO 2 e per ha total

Biosolids reclamation GHG emissions? • Need to consider emissions from biosolids management • Also Biosolids reclamation GHG emissions? • Need to consider emissions from biosolids management • Also alternate biosolids end-uses

Biosolids to Agriculture vs. -220 Mg CO 2 e soil C -275 Mg CO Biosolids to Agriculture vs. -220 Mg CO 2 e soil C -275 Mg CO 2 e biomass C +18 Mg CO 2 e N 2 O +2 Mg CO 2 e transport (50 km) • Net: -475 Mg CO 2 e • • • -140 Mg CO 2 e soil C • -28 Mg CO 2 e fertilizer credit • +11 Mg CO 2 e transport (300 km) • Net: -157 Mg CO 2 e

Biosolids to Landfill vs. -220 Mg CO 2 e soil C -275 Mg CO Biosolids to Landfill vs. -220 Mg CO 2 e soil C -275 Mg CO 2 e biomass C +18 Mg CO 2 e N 2 O +2 Mg CO 2 e transport (50 km) • Net: -475 Mg CO 2 e • • • -29 Mg CO 2 e soil C • 346 Mg CO 2 e fugitive GHG • +14 Mg CO 2 e transport (350 km) • Net: +331 Mg CO 2 e

Net GHG balance of restoring vegetation • Biosolids reclamation § -475 Mg CO 2 Net GHG balance of restoring vegetation • Biosolids reclamation § -475 Mg CO 2 e (30 years, 1 ha, 100 dt biosolids) • Conventional reclamation § -293 Mg CO 2 e • What if development is chosen instead?

Suburb development • Single-family houses • Asphalt roads • Built cover % according to Suburb development • Single-family houses • Asphalt roads • Built cover % according to USGS • Reclaim remaining land

Suburb development: Housing • US Census population density § 3. 9 houses/ha @ 243 Suburb development: Housing • US Census population density § 3. 9 houses/ha @ 243 m 2 (~2, 500 sq. ft) • LC GHG estimates: § Construction (incl. materials): 283 Mg CO 2 e § Maintenance/occupatio n: 989 Mg CO 2 e

Suburb development: Roads • USGS % impervious cover § 0. 44 ha ha-1 suburb Suburb development: Roads • USGS % impervious cover § 0. 44 ha ha-1 suburb • LC GHG estimates: § Construction (incl. materials): 93 Mg CO 2 e § Maintenance: 42 Mg CO 2 e

Net GHG balance of Suburb Development • • • +1, 272 Mg CO 2 Net GHG balance of Suburb Development • • • +1, 272 Mg CO 2 e houses +135 Mg CO 2 e roads -52 Mg CO 2 e soil C -86 Mg CO 2 e biomass C Net: +1, 269 Mg CO 2 e • Extra commuter traffic GHG? § Excluded from LCA but. . . § ca. +1, 653 Mg CO 2 e over 30 yr

Development or Reclamation? vs. • Net: -293 to -475 Mg CO 2 e • Development or Reclamation? vs. • Net: -293 to -475 Mg CO 2 e • Net: +1, 269 Mg CO 2 e • Modify and recombine scenarios to look for best and worst cases.

Worst Case + • • Low density suburb, and. . . Send biosolids to Worst Case + • • Low density suburb, and. . . Send biosolids to landfill, and. . . Conventional reclamation of partial land +1, 600 Mg CO 2 e – largest emissions, lowest offsets

Optimized Case + • Housing construction in urban core, and. . . • Biosolids Optimized Case + • Housing construction in urban core, and. . . • Biosolids for full reclamation • -5 to +141 Mg CO 2 e – minimized emissions, maximized offsets

Other ecosystem services • Improved with reclamation over development: § Water filtration; Biodiversity; Tourism Other ecosystem services • Improved with reclamation over development: § Water filtration; Biodiversity; Tourism value + + +

Conclusions • Land-use after reclamation has the biggest impact • Biosolids end-use is also Conclusions • Land-use after reclamation has the biggest impact • Biosolids end-use is also has an impact § and is determined in part by land-use choices • Biosolids in Puget Sound may have best enduse in reclamation § but first need to not develop (degraded) land