Bioremediation in San Francisco
The premise: soil contaminants from urban activity are a threat to urban agriculture --and human and environmental health-- in cities like San Francisco. Bioremediation offers a potential solution in areas suitable for urban agriculture.
A Two-step Approach:
created a list of spatial criteria for urban agriculture in San Francisco
Where is urban agriculture permitted?
Where is there space?
Which areas are likely to have more contaminated soil?
-near a school
-meets criteria
-zoning: commercial or low-density residential-mixed use
2. Bioremediation plan for one such suitable site
What is bioremediation?
Phytoremediation
Mycoremediation
phytoextraction
phytostabilization
phytodegredation
Advantages of site-specific bioremediation
brownfields
environmental risks: concentration of heavy metals in the food chain, long latency periods, consequence for species abundance
health risks: cancer, respiratory/reproducive maladies
public welfare risks: resource use restrictions on groundwater and land use, decreased property values
economic benefits:
one study found bioremediation raised commercial property values by 30%; brownfield sites attractive to developers because infrastructure/location in city already exists. Restore tax base, new jobs, maybe higher building density. Other forms of remediation are expensive.
Using native plants achieves a dual goal of site cleanup and habitat restoration during the brownfield to greenspace transition
Contaminants
Petroleum
Water holding capacity: 50-80% moisture saturation of soil
Adequate supply of oxygen and organic nutrients
pH of 6 to 8
N, P, C, K, Ca, Mg, S, Fe
Temperature: peak at 30-40*C
No
Plants
California sagebrush
California poppies
Narrow-leaved bedstraw
Black sage
Yes
Fungi
Acremonium
Aspergillus
Aureobasidium
Candida
(and about fifteen others)
Composting
Microbial and fungal
Case study of airforce base: saved the base $133,000
Lead
Plants
Climate
Soil compaction
Soil type
Sunlight
Seapink thrift
Ragweed
Indian mustard
Rutabaga
Kale, broccoli, and cabbage
California Sunflower
Pennycress
Wheat
Corn
lower soil pH and add P
pH of less than 5.6
Fungi
Good levels of oxygen, moisture
Arbuscular Mycorrhizal Fungi
Monitoring
Metrics
Future Action Reclamation Mob
1. Geographic Information Systems (GIS) Analysis
based on existing conditions and trends in urban agriculture
Our spatial criteria answer the questions:
Example of a suitable site