1. Is urban pollution a menace
to urban agriculture?
Erik J Joner
Senior scientist, Bioforsk Soil & Environment
Ås, Norway
Erik.Joner@bioforsk.no

2. Overview
 About environmental pollutants
 Classification of soil and soil amendments
 Results from soil and plant analyzes
 Cause for concern?

3. About environmental pollutants
Anthracene (ANT)
Heavy metals
 Essential (Zn, Cu, Co)
 Non-essential (Pb, Cd, Ni, Cr, As, …)
Chrysene (CHR)
Organic pollutants (more or less degradable)
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Polycyclic aromatic hydrocarbons (PAH)
Halogenated (Cl, Br, F) compounds (e.g PCB)
Phenols
Pesticides
Soot
Dibenzo(a,h)anthracene (DBA)
PAH, examples
Biological contamination
 Bacteria, fungi, viruses, protozoa
Polychlorinated biphenyls (PCBs)

4. Sources of pollution
Current:
 Combustion
• Transportation
• Domestic burning of firewood
• Waste incineration
 Sewage sludge
 Long range transport
• Industry
Past
• Industry
• Transportation (Pb)
• Waste disposals
• Naturally metal rich soils (Alun shales)

5. How do pollutants get into plants?
Form soil (mostly)
 Metals
From air (a little bit)
 Metals and organic pollutants
 Disease (Mildew)
From fertilizer/manure/watering
 Human pathogens

6. Transfer from roots to shoots
HM
Strong barriers
 From soil to roots
 From roots to shoots
 Into seeds/pollen
Dilution effect
 Well fertilized plants have smaller
root systems and more edible parts
HM

7. Metal concentrations in soil
Arsenic
Cadmium
Chromium
Copper
Nickel
Lead
Zinc
39
6
Cobalt
85
36
35
11
117
Herligheten,
Mineral
produced soil, Oslo
Organic
19
44
37
John Colletts plass,
Outer
58
87
53
33
45
111
urban soil, Oslo
Inner
38
94
36
38
34
120
Fokhol
Low
19
1.8
10
45
48
55
21
143
bio-dynamic farm, Hedemark
High
20
2.0
14
56
57
86
21
178
Means for arable
Mean
5*
0.22
27
19
21
24
64
Norwegian soils
Low
0.03
1
2
1
4
7
High
2
92
87
86
77
356
 Urban soils are within the range of arable soils

8. Upper limit for metals
in kindergarten soils

9. Plant analyses, 2012

10. Transfer from roots to shoots
Total vs. bioavailable metals
 Zn in soil: 120 mg/kg i 1 m2 -> 200 L = 500
kg: 60 g -> 1 ha: 600 kg
 Zn in plants: 50 mg/kg -> 4000 kg barley/ha:
200 g Zn i harvested grain
 0,03% taken up in edible parts

11. Metals and PAH in honey

12. Cause for concern?
 Take home message: Urban agriculture is safe
 Very low levels in plants grown on clean soil
But:
 Some soils in the city may be polluted by spills or old industry
 If in doubt, consult EPA maps of polluted sites
 Wash leafy plants and peel roots/tubers
 How large proportion of your diet is from urban grown food?
 Respiratory intake from city air is surpassing food intake