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Table 1 Ranges of Cd, Cu, Pb, and Zn concentrations reported for surface soils in (peri)urban garden soils worldwide (mg/kg; total/pseudo-total concentrations)

From: Low presence of potentially toxic elements in Singapore urban garden soils

Location; garden type

Cd

Cu

Pb

Zn

Issues mentioned

References

Belo Horizonte, MG, Brazil; urban gardens

0.11–0.20a

16–42a

11–30a

ND

Proximity to potential sources

Dala-Paula et al. (2018)

Jos, Nigeria; cultivated soils

0.08–0.19

1–4

3–5

8–13

Urban ash (deposition, soil amendment)

Pasquini and Alexander (2004)

Nanjing, China; peri-urban ag soils

0.08–0.15a

21–30a

31–33a

53–71a

Deposition; industrial effluent

Huang et al. (2006)

Salamanca, Spain; urban gardens

0.07–0.33

ND

10–26

ND

Fertilizers (Cd); trafficking (Pb)

Sanchez-Camazano et al. (1994)

Visakhapatnam, India; semi-urban

ND

11–31a

15–48a

43–50a

Proximity to industry

Srinivas et al. (2009)

Alice, S Africa; home garden soils

0.10–0.80a

5–8a

5–14a

18–53a

Minor contamination

Bvenura and Afolayan (2012)

Toronto; community gardens

0.27–0.40

22–33

19–96

ND

Trafficking processes

Wiseman et al. (2013)

Guangzhou, China; urban veg gardens

0.02–1.9

6–25

25–55

57–195

Atmospheric deposition

Xiong et al. (2016)

Namyangju, Korea; urban field near road

bdl

15–30

14–18

61–77

Inconclusive; some road effects

Kim et al. (2017)

Thessaloniki, Greece; Peri-urban farm plots

0.16–0.26

18–40

16–37

3–124

Proximity to industry was NOT an issue

Vousta et al. (1996)

Wuxi, China; peri-urban ag soils

0.14–0.17a

35–37a

38–42a

104–112a

Deposition; industrial effluent

Huang et al. (2006)

Rostock, Germany; urban garden soils

0.05–0.60

1–59

3–57

3–95

Diffuse; highest in city center

Kahle (2000)

Sakai, Osaka; (peri)urban veg farms

~ 0.25–0.90a

~ 10–30a

~ 10–35a

~ 30–125a

Redistribution of legacy metal; trafficking

Komai and Yamamoto (1982)

Skarżysko-Kamienna, Poland; allot. gardens

0.30–5.8

3–15

7–33

2–99

Inconclusive; probably industrial

Świercz and Zajęcka (2018)

Kabul, Afghanistan; urban gardens

0.15–0.20

50–66

25–33

113–184

Traffic, war, contaminated irrigation water

Safi and Buerkert (2011)

New Brunswick, CA; residential gardens

~ 0.02–0.05

~ 18–34

~ 27–115

~ 77–145

Industrial legacy; long-term deposition

Pilgrim and Schroeder (1997)

Baoding, China; sewage-irrigated soils

0.17–0.40

26–44

27–58

113–250

Sewage irrigation water

Xue et al. (2012)

Szeged (Bakto), Hungary; urban gardens

0.27–2.86

19–580

5–61

33–199

Traffic; pesticides

Szolnoki et al. (2013)

Jiangsu cities (China); peri-urban ag soils

ND

38–45a

88–120a

45–47a

Industrial, urban processes

Hao et al. (2009)

Manitoba province, CA; urban ag soils

0.8–1.7

16–37

24–43

62–110

Road phenomena most likely

Mills & Zwarich (1975)

Beijing, China; gardens and green spaces

0.14–0.24a

28–50a

30–74a

78–118a

Age, traffic processes, urban sources

Beavington (1975)

Torun, Poland; botanical garden topsoil

bdl

bdl–30

bdl–148

6–142

Natural soil genesis

Charzyński et al. (2018)

Cowra (Au); commercial/residential gardens

0.01–0.80

1–96

7–12

9–336

No main pollution sources

Kachenko and Singh (2006)

Beijing (Tongzhou); irrigated soils

0.41–1.71

22–49

48–53

136–176

Waste-water irrigation

Khan et al. (2008)

Varnasi city, India; suburban garden soils

0.90–5.65

3–30

9–25

22–208

Waste-water irrigation

Sharma et al. (2006)

Koszalin, Poland; allotment soils

0.04–0.53a

8–34a

8–57a

78–220a

Natural signature; garden management

Bielicka-Giełdoń et al. (2013)

Singapore; urban gardens

bdl–3.2

10–77

bdl–37

71–164

Proximity to industry/roads & industry; diffuse urban signal

This study

Mumbai, India; railway gardens

0.1–1.1

60–231

3–7

15–111

Irrigation water; pesticides; railway signal

Vazhacharickala et al. (2013)

Ho Chi Minh City; urban ag lands

ND

8–70

bdl–27

bdl–272

Amendments (fert/pest); urban waste

Tran et al. (2020)

Vancouver, Ca; community garden

ND

36–63

22–82

51–133

Legacy deposition, roads, industry

Oka et al. (2014)

Kano City, Nigeria; urban veg gardens

2.3–4.0

5–14

2–17

17–233

Irrigation wastewater

Abdu et al. (2011)

Oregon (Corvallis, Portland); food gardens

bdl–0.57

25–109

0.2–347

ND

Not determined; compost concerns

Nelson (2018)

Seoul, Korea; rooftop gardens

0.9–1.9

6–118

6–21

51–268

Deposition (local and long-distance)

Kim et al. (2015a, b)

Shangdong towns (China); garden soils

0.03–0.99

1–160

9–27

25–223

Trafficking; industry; waste irrigation

Liu et al. (2011)

Zurich; urban gardens

ND

16–34

19–1076

ND

Legacy (esp. Pb); deposition

Tresch et al. (2018)

Nanjing, China; peri-urban ag soils

0.19–0.58

22–58

21–150

76–181

Fertilizers; deposition; industry emissions

Hu et al. (2018)

Guelph, Ontario, CA; Community gardens

0.38–1.84

ND

16–151

97–503

Low-income area; legacy

Montaño-López and Biswas (2021)

Kaduna, Nigeria; river bank gardens

0.07–0.95

11–36

26–154

53–218

Deposition; vehicular emissions

Agbenin et al. (2009)

Lisbon area; urban allotment soils

ND

10–62

1–110

33–146

Uncertain; roads/airport likely

Leitão et al. (2018)

Nanjing; urban/suburban gardens

ND

23–72

35–84

100–283

Decreases from urban to rural

Fang et al. (2011)

Kunming, China; peri-urban garden

0.53–0.80

87–208

42–62

77–148

Geogenic; manure inputs; uncertain

Zu et al. (2014)

Bragança, Portugal; peri-urban gardens

0.9 ± 0.2a

128 ± 28a

56 ± 78a

89 ± 28a

Organic farming; new city sources

Arrobas et al. (2017)

Dar es Salaam, Tanzania; urban ag

0.15–0.26a

4–8a

9–33a

13–57a

Uncertain; contaminated irrigation water

Kibassa et al. (2013)

Delhi, India; peri-urban soils

2.28–2.51a

24–77a

21–59a

73–175a

Wastewater irrigation, fertilizer, deposition

Bhatia et al. (2015)

Kayseri, Turkey; urban veg gardens

1–48-2.11a

44–68a

67–108a

128–179a

Not determined

Tokalioglu et al. (2006)

Danang, Vietnam; urban ag/garden soils

0.1–0.7

30–495

1–5

53–562

Air-borne pollutants; ag amendments

Thuy et al. (2000)

Johannesburg, SA; school veg gardens

ND

bdl–80

27–100

91–427

Proximity to pollution sources

Kootbodien et al. (2012)

Hanoi, Vietnam; urban farm soils

3.9–4.5

195–230

125–145

187–263

Contaminated irrigation water

Nguyen et al. (2010)

Harare, Zimbabwe, metropolitan farms

1.0–3.4

21–94

17–59

42–228

Irrigation with wastewater

Mapanda et al. (2005)

Hyderabad, Pakistan; unclear

1.6–4.3a

11–32

21–67

105–209

Wastewater irrigation

Jamali et al. (2007)

Kano City, Nigeria; garden soil

1.4–9.6a

ND

16–91a

77–246

Inconclusive; irrigation water suspected

Egwu and Agbenin (2013)

Tacoma, Washington, USA; urban gardens

0.30–0.80a

32–118a

38–110a

100–219a

Uncertain; past management effects

McIvor et al. (2012)

Melbourne; urban garden soil

0.12–1.04

ND

13–773

ND

House age; distance to roads

Kandic et al. (2019)

Lisbon, Portugal; urban allotment gardens

bdl

5–87

23–245

35–208

Industry; traffic phenomena

Bechet et al. (2018)

Hue City, Vietnam; peri-urban farms

0.03–0.44

3–39

4–25

12–212

Irrigation water; flood disposition

Pham et al. (2021)

Ottawa, CA; garden soils

0.11–0.75

6–42

16–547

50–380

Age; limited industrial activity

Rasmussen et al. (2001)

Hangzhou; urban–rural vegetable soils

0.10–0.64

14–78

20–87

59–265

Agrichemicals; vehicles exhaust; industry

Chen et al. (2008)

Xianyang (China); suburban garden soil

0.2–2.45

6–50

24–132

40–526

Plastic, fertilizers, traffic, industry

Wang et al. (2018)

Hong Kong area; market garden soils

0.25–2.17

5–67

24–113

20–232

Urbanization and traffic volume

Wong (1996)

Plock city, Poland; allotment gardens

0.41 [2.12]+

9 [38]+

9 [24]+

313 [2947]+

Dust fall (Industry, transportation)

Mikula and Indeka (1997)

Perth, Australia; former market gardens

0.02–0.66

2–68

3–174

6–304

Construction; roads; waste disposal

Rate (2021)

Wuxi, China; peri-urban ag soils

bdl–0.14

27–152

17–162

30–445

Trafficking, industry, manufacturing

Zhao et al. (2007)

Connecticut; community gardens

bdl

20–75a

22–450a

60–238a

Not identified specifically

Stilwell et al. (2008a)

Wollongong, Australia; home gardens

1.99 ± 0.3

847 ± 114

13.3 ± 3.1

229 ± 17

Proximity to Cu smelter

Beavington (1975)

Taiwan; urban park soils++

bdl–3.33

9–117

8–57

49–379

Industry sources

Jien et al. (2011)

Guangdong, China; vegetable gardens

0.26–1.17

210–450

73–134

92–142

E-waste processing

Luo et al. (2011)

Kaduna, Nigeria; urban field gardens

ND

18–85

160–200

156–433

Wastewater irrigation; waste disposal

Akpa and Agbenin (2012)

Naples, Italy; urban gardens

ND

~ 20–85

~ 75–325

~ 50–450

Traffic, Industry, ag amendments

Imperato et al. (2003)

Vienna, Austria; buried pots in gardens

~ 0.10–0.75

ND

~ 5–165

74–2600

Great variability reported

Ziss et al. (2021)

Southampton (UK); urban horticulture soils

0.14–0.80

19–86

34–488

60–485

Geology; mixed (indust, petrol, burning)

Crispo et al. (2021)

Adelaide, Australia; urban ag sites

0.01–0.38

25–183

30–268

< 1–662

Legacy (industry)

Salomon et al. (2020)

Vancouver, CA; urban gardens/farms

bdl

35–127a

69–208a

77–887a

Not explored

Thomas (2013)

Nantes, France; urban allotment gardens

0.1–17.7

13–117

19–229

26–272

Industry; traffic phenomena

Bechet et al. (2018)

Bottrop, Germany; variety of urban gardens

~ 1.8–2.7

~ 15–145

~ 50–155

~ 125–295

Inconclusive

Burghardt and Schneider (2018)

Zagreb, Croatia; urban/suburban ag

0.25–3.85

4–183

1–139

15–277

Multiple anthropogenic processes

Romic and Romic (2003)

Harrisburg, PA (USA); potential gardens

ND

11–46a

26–402a

30–216a

Legacy Pb; road phenomena

Kessler et al. (2013)

Madrid, Spain; community gardens

ND

11–59

15–598

72–309

Landuse history; proximity to urban center

Izquierdo et al. (2015)

Île-de-France, France; market gardens

0.55–0.99

81–156

229–436

231–367

Legacy (industry, sludge disposal)

Barbillon et al. (2019)

Cotorro, Havana; peri-urban gardens

ND

50–945

21–731

91–7739

Wind direction (smelter)

Díaz Rizo et al. (2015)

Torino, Italy; gardens and parks

ND

40–293

17–565

75–550

Diffuse pollution

Hursthouse et al. (2004)

Baton Rouge, LA, USA; peri-urban

ND

6–189

11–967

32–1031

Industry, construction, traffic

Weindorf et al. (2012)

Sheffield, UK; gardens/allotments

ND

~ 45–180

~ 70–600

~ 185–750

Varies by land use; e legacy metals

Weber et al. (2019)

Gyongyosoroszim, Hungary; veg gardens

0.22–13.60

ND

21–694

97–2050

Flood water from old Zn/Pb mine

Sipter et al. (2008)

Hangzhou, China; suburb veg gardens

ND

4–144

14–98

76–302

Organic manuring

Wuzhong et al. (2004)

Porto, Portugal; urban ag/farm soils

0.1–1.1

10–248

27–415

92–465

Airport; oil refinery; roads

Cruz et al. (2014)

Madrid; parks and gardens; other

ND

18–194

31–463

82–514

Waste sludge; fertilizers; roads; other

De Miguel et al. (1998)

Nates, France; community garden

ND

16–151a

28–5785a

32–193a

Anthropogenic and geogenic

Jean-Soro et al. (2015)

Nova Scotia; community/yard gardens

ND

11–108

10–767

42–350

Various potential anthropogenic sources

Heidary-Monfared (2011)

Washington DC; urban farm/garden

ND

13–159

16–869

32–607

Legacy and urban/trafficking sources

Long (2010)

Liverpool (UK); urban horticulture soils

0.19–2.2

27–166

76–514

94–497

Geology; mixed (industry, petrol, burning)

Crispo et al. (2021)

Leicester (UK); urban horticulture soils

0.25–4.8

27–110

76–454

127–614

Geology; mixed (industry, petrol, burning)

Crispo et al. (2021)

Columbus and Cleveland; established gardens

0.93–4.15

23–101

31–553

97–645

Legacy (Pb paint); prior activities

Kaiser et al. (2015)

Ghent, Belgium; urban gardens

0.16–4.91

11–107

55–385

39–1325

Road phenomena; general industry signal

Folens et al. (2017)

Hong Kong; urban parks

0.02–5.89

5–190

5–404

39–435

Age; amendments (fertilizers), road dust

Li et al. (2001)

Sevilla, Spain; parks/ag/gardens

0.18–4.85

14–198

23–725

39–326

Trafficking; organic amendments

Ruiz-Cortes et al. (2005)

Newcastle (UK); urban horticulture soils

0.43–1.1

25–246

82–501

185–629

Geology; mixed (industry, petrol, burning)

Crispo et al. (2021)

Montreal, CA; urban gardens

0.4–1.8a

15–400a

150–400a

210–300a

Compost; highly variable

Murray et al. (2011)

Buffalo & NYC, NY; urban farms/gardens

BDL–3.6

40–83

18–3620

136–1060

Deposition; non-uniform contamination

McBride et al. (2014), Cai et al. (2016)

Wales & England; urban soils only

0.4–1.9

4–75

14–680

6–744

Trafficking, industry, mining, other

Davies (1978)

Dublin area; garden soils

> 3–5

11–145

39–540

117–940

Wind direction from urban sources

Fleming and Parle (1977)

Sevilla, Spain; allotments and parks

ND

14–698

14–1080

38–611

Vehicular sources

Hursthouse et al. (2004)

Leeds (UK); urban horticulture soils

0.24–2.5

33–372

104–1682

139–503

Geology; mixed (industry, petrol, burning)

Crispo et al. (2021)

Milton Keynes (UK); urban horticulture soils

0.21–6.5

19–228

29–3943

89–413

Geology; mixed (industry, petrol, burning)

Crispo et al. (2021)

Bangkok, Thailand; general urban soils++

0.05–2.53

5–283

12–269

3–814

Soil type; urban processes; roads

Wilcke et al. (1998)

Breschia, Italy; home gardens

bdl–4.00

28–410

36–207

58–845

Proximity to industry

Ferri et al. (2015)

Connecticut; comm and res gardens

bdl–3.5

bdl–900

bdl–3490

15–520

Not identified specifically

Stilwell et al. (2008b)

Los Angeles; urban gardens

0.11–4.27

ND

18–1720

ND

Proximity to roads; age of neighborhood

Clarke et al. (2015)

Edinburgh (UK); urban horticulture soils

0.30–2.4

33–103

84–1229

138–996

Geology; mixed (industry, petrol, burning)

Crispo et al. (2021)

Nottingham (UK); urban horticulture soils

0.54–4.6

42–127

124–1019

235–862

Geology; mixed (industry, petrol, burning)

Crispo et al. (2021)

Quezon City, Philippines; cropped soils

ND

84–784

300–6550

bdl–1817

Urban processes; landfill legacy

Navarrete et al. (2017)

Melbourne (AU); residential veg gardens

ND

bdl–323

bdl–3341

bdl–3003

Age (e.g., for lead); road/rail proximity

Laidlaw et al. (2018)

Mexico City; garden, park & other soils

ND

15–398

5–452

36–1641

Trafficking/roads; Industrial sources

Morton-Bermea et al. (2009)

Sydney (AU); urban veg gardens

ND

33–717

14–3080

50–2020

Inner city has high lead legacy

Rouillon et al. (2017)

Wroclaw, Poland; allotment gardens

ND

13–595

13–659

38–2103

Proximity to pollution sources

Kabala et al. (2009)

Chicago; various urban gardens/farms

ND

9–19a

34–449

38–69a

Not substantiated

Witzling et al. (2010)

Christchurch; urban gardens

0.33–10.7

12–118

23–2615

68–799

Age (pre-1950 neighborhoods)

Ashrafzadeh et al. (2018)

Cardiff (UK); urban horticulture soils

0.15–4.3

10–216

30–2149

46–1213

Geology; mixed (industry, petrol, burning)

Crispo et al. (2021)

Bristol (UK); urban horticulture soils

0.46–3.3

14–752

88–1211

115–960

Geology; mixed (industry, petrol, burning)

Crispo et al. (2021)

Copenhagen, Denmark; urban gardens

 ~ 0.3–3.7a

 ~ 10–450a

 ~ 10–600a

 ~ 40–1260a

Inconclusive; urban signal

Warming et al. (2015)

Gijón (Asturias, Spain); peri-urban soils

0.4–2.3

6–244

33–585

64–1047

Coal combustion; unidentified sources

Boente et al. (2017)

Marseille, France; veg gardens

0.16–8.86

14–473

20–566

43–1020

Chemical fertilizers, fungicides

Zhong et al. (2022)

New York (USA); community gardens

bdl–3.1

6–598

11–2455

21–2317

Legacy Pb; long-term urban processes

Mitchell et al. (2014)

Baltimore, MA, (USA); urban gardens

0.02–13.65

1–97

1–10,900

< 1–4880

Legacy (inner city); urban activities

Mielke et al. (1983)

Paris area (France); Ag + urban gardens

0.90–15.0

ND

42–854

100–1292

Deposition legacy (mining, smelting)

Pelfrêne et al. (2012)

Baltimore (USA); urban farms/gardens

ND

~ 20–300

~ 7–1000

~ 50–600

Not determined; produce was safe

Lupolt et al. (2021)

Brooklyn, NY; urban gardens

ND

53–328a

66–1025a

150–1474a

Legacy urban pollutants

Egendorf et al. (2018)

San Francisco (USA); garden soils

bdl–8.14

2–2630

7–2040

33–707

Home age

Gorospe (2012)

Washington DC; urban gardens

0.2–6.6

8–240

44–5300

74–2600

Proximity to homes (esp. Pb); variable

Preer et al. (1984)

Noyelles-Godault (France); kitchen gardens

2.8–21.1

ND

190–1425

199–2429

Former mining/smelter area

Douay et al. (2013)

Paris area (France); kitchen garden soils

17.2–23.9a

ND

387–1708a

2350–2871a

Garden amendments; ag practices

Waterlot et al. (2011)

Kampala City, Uganda; peri-urban ag

0.12–21.0

26–1690

10–653

49–3270

Inappropriate waste disposal

Nabulo et al. (2012)

Boolaroo (Australia); residential veg garden

0.01–27.49

3–223

12–1626

45–4014

Former Pb–Zn smelter area

Kachenko and Singh (2006)

Port Kemba (Australia); residential veg garden

0.01–7.01

65–1032

14–430

87–1947

Former Cu smelter area

Kachenko and Singh (2006)

Palmerton, PA (USA); garden soils

18–113

41–595

90–370a

1420–13,100

Proximity to Zn smelter

Chaney et al. (1988)

Glasgow, Scotland; allotments and parks

ND

52–484

250–7051

164–1004

Diffuse pollution

Hursthouse et al. (2004)

Hong Kong; roadside gardens/parks

ND

13–553

42–1034

173–11,316

Road pollution

Tam et al. (1987)

New York (USA); urban gardens

0.1–11.0

5–1286

3–8912

35–2352

Legacy (lead; incineration); pesticides

Cheng et al. (2015)

New Orleans, LA (USA); urban ag

0.25–8.80

2–200

1–9540

18–7330

Legacy (Pb); current road/industry

Moller et al. (2018)

Newcastle, Australia; private spaces

3.0–9.0

44–1040

42–11,600

140–8570

Legacy Cu; smelting (slag waste)

Harvey et al. (2017)

Baia Mare, Romania, (peri)urban gardens

1.2–13.8

171–2130

797–10,200

376–2130

Legacy and deposition (mining, smelter)

Mihali et al. (2012)

Dalnegorsk, Russia; garden/other soils

7–26

29–805

213–5621

593–5438

Mining, smelter, industry

Von Braun et al. (2002)

London Boroughs (UK); garden-veg plot soils

bdl–68

8–2320

28–13,700

34–2780

Home age

Culbard et al. (1988)

  1. aPertains to a range of means or a mean ± standard deviation; otherwise, entries are ranges (min–max)
  2. ~Values are approximated from a graph
  3. +Signals that values are means and maximums
  4. ++Not an agriculture study, but in close proximity to Singapore