Effects of Biochars on ecotoxicological indicators

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1 Effects of Biochars on ecotoxicological indicators

2 Biochars characteristics Feedstock and origins: Biochar Code Feedstocks Production Scale Pyrolysis Temperature BC1 R PmW-BC Poultry manure and wood Pilot 500 BC2 R D1-BC Digestate of corn and rye Pilot 500 BC3 R D2-BC Digestate from a biogas plant Industrial 700 BC4 R W1-BC Forestry Residues Industrial 650 BC5 R W2-BC Forestry Residues Pilot 500 BC6 R WC-BCX Vegetable and forestry wastes; refuse Pilot 500 compost BC7 R D3-BC Digestate from a biogas plant Pilot 500 BC8 R Pig-BC Pig manure Pilot 500

3 Ecotoxicological risk assessment

4 Ecotoxicological risk assessment

5 Potential Toxic Elements and Organic Pollutants Potential Toxic Elements (PTE) Heavy metals present in feedstocks are not destroyed by pyrolysis Arsenic (As), Cadmium (Cd), Chromium (Cr), Copper (Cu), Mercury (Hg), Molybdenum (Mo), Nickel (Ni), Lead (Pb), Selenium (Se), Zinc (Zn) Potential Organic Pollutants (POP): Polychlorinated biphenyls (PCBs) : present in feedstock Polycyclic aromatic hydrocarbons (PAHs) and Dioxins and furans (PCDDs and PCDFs) : produced during pyrolisis

6 Potential Toxic Elements - Contents Parameter Biochar D1-BC D2-BC D3-BC W1-BC W2-BC WC-BCX PmW-BC Pig-BC Arsenic As mg/kg dry wt < 4,07 < 4,05 < 4 < 4,06 < 4 < 4 < 4,04 < 4 Cadmium Cd mg/kg dry wt 0,7 < 0,2 0,2 < 0,2 0,2 0,5 0,89 0,8 Chromium Cr mg/kg dry wt 26,7 18,2 20,3 17,2 4,5 30, ,7 Copper Cu mg/kg dry wt 93 92, ,2 14,7 48, ,2 Mercury Hg mg/kg dry wt < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 Molybdenum Mo mg/kg dry wt 5,56 3,96 4,66 1,93 < 0,4 2,7 5,11 10,85 Nickel Ni mg/kg dry wt 16,8 11,3 7,5 17,4 3,3 11, ,1 Lead Pb mg/kg dry wt 8,7 < 5,1 20,1 7,1 < 5 64,9 < 5 6,5 Selenium Se mg/kg dry wt < 3,06 < 3,04 < 1,5 < 3,04 < 1,5 < 1,5 < 3,03 1,7 Zinc Zn mg/kg dry wt 413,8 494,1 360,3 177,8 215,9 222,1 971,5 1475,8 As, Hg, Se: for all biochars, below the LOQ (Limit of Quantification) Others heavy metals : levels are low One biochar stood out from the others : Pig-BC Pig manure generally contains various heavy metals such as copper and zinc

7 Potential Toxic Elements - Contents Parameter Guidelines International Biochar European Biochar Biochar Quality Arrêté 8 janvier 1998 Initiative (IBI) Certificate (EBC) Mandate (BQM) Epandage boues STEP Arsenic As mg/kg dry wt Cadmium Cd mg/kg dry wt 1,4-39 < 1-1, Chromium Cr mg/kg dry wt < Copper Cu mg/kg dry wt < Mercury Hg mg/kg dry wt 1-17 < Molybdenum Mo mg/kg dry wt Nickel Ni mg/kg dry wt < Lead Pb mg/kg dry wt < Selenium Se mg/kg dry wt Zinc Zn mg/kg dry wt < Comparison with limits defined by 3 guidelines and 1 french regulation All the biochars are below these limits International Biochar Initiative (IBI) Standards V2 : European Biochar Certificate (EBC) Guidelines V6.1 : Biochar Quality Mandate (BQM) Version for public consultation V1.0 : Arrêté du 8 janvier 1998 fixant les prescriptions techniques applicables aux épandages de boues :

8 Potential Toxic Elements - Fluxes Fluxes of heavy metals for a application dose of 5 tons dw/ha 1) Comparison with limits defined by french regulation for the fertilizers registration All the biochars are below except Pig-BC for copper and zinc ( Cu Flux = 4471 g/ha > Max Flux = 1000 g/ha ; Zn Flux = 7380g/ha > Max Flux = 3000g/ha) 2) Ecotoxicological risk assessment characterized by Risk Characterization Ratio (RCR) RCR = PEC PNEC RCR < 1 : No risk RCR >> 2 : Confirmed risk Predicted Environmental Concentration Concentration of the toxicant that might be expected to be found in an ecosystem Calculated value (flux) Predicted No Effect Concentration Concentration of the toxicant below wich adverse effects are unlikely to occur Estimated value (toxicity data) RCR << 1 for all heavy metals in Biochars

9 Potential Organic Pollutants PCBs PAHs Dioxins Furans Parameter Biochar D1-BC D2-BC D3-BC W1-BC W2-BC WC-BCX PmW-BC Pig-BC Congeners 28 mg/kg dry wt < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 Congeners 52 mg/kg dry wt < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 Congeners 101 mg/kg dry wt < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 Congeners 118 mg/kg dry wt < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 Congeners 138 mg/kg dry wt < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 Congeners 153 mg/kg dry wt < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 Congeners 180 mg/kg dry wt < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 Sum of 7 PCB mg/kg dry wt < 0,07 < 0,07 < 0,07 < 0,07 < 0,07 < 0,07 < 0,07 < 0,07 Acenaphtene mg/kg dry wt 0,038 0,046 0,01 < 0,01 0,036 0,015 < 0,01 0,041 Acenaphtylene mg/kg dry wt < 0,01 < 0,01 0,01 < 0,01 < 0,01 < 0,01 0,01 0,012 Anthracene mg/kg dry wt 0,044 < 0,01 0,1 < 0,01 0,08 0,033 0,031 0,08 Benzo(a)anthracene mg/kg dry wt 0,013 < 0,01 0,049 < 0,01 0,026 0,018 0,017 0,039 Benzo(a)pyrene mg/kg dry wt < 0,01 < 0,01 0,032 < 0,01 0,015 0,019 0,024 0,053 Benzo(b)fluoranthène mg/kg dry wt < 0,01 < 0,01 0,024 < 0,01 < 0,01 < 0,01 0,012 0,021 Benzo(k)fluoranthène mg/kg dry wt < 0,01 < 0,01 0,019 < 0,01 < 0,01 < 0,01 < 0,01 0,012 Benzo(ghi)perylene mg/kg dry wt < 0,01 < 0,01 0,023 < 0,01 < 0,01 0,015 0,02 0,016 Chryseme mg/kg dry wt 0,018 < 0,01 0,06 < 0,01 0,026 0,019 0,03 0,13 Dibenzo(ah)anthrocene mg/kg dry wt < 0,01 < 0,01 0,033 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 Fluoranthene mg/kg dry wt 0,04 < 0,01 0,125 < 0,01 0,045 0,021 0,031 0,085 Fluorene mg/kg dry wt 0,076 < 0,01 0,13 < 0,01 0,15 0,08 0,067 0,15 Indeno(123CD)pyrene mg/kg dry wt < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 < 0,01 0,013 < 0,01 Naphtalene mg/kg dry wt 0,198 0,32 0,31 0,041 0,32 0,1 0,254 0,35 Phenanthrene mg/kg dry wt 0,147 < 0,01 0,309 < 0,01 0,277 0,09 0,085 0,262 Pyrene mg/kg dry wt 0,04 < 0,01 0,14 < 0,01 0,086 0,033 0,037 0,099 Sum of 16 HAP mg/kg dry wt 0,649 0,436 1,379 0,116 1,091 0,468 0,646 1,36 1,2,3,4,6,7,8-Heptachlorodibenzodioxin ng/kg dry wt 0,1504 0,065 0,2 0,222 0,116 0,114 0,1342 0,0787 1,2,3,4,6,7,8-Heptachlorodibenzofuran ng/kg dry wt 0,1387 0,072 0,056 0,08 0,074 0,059 0,0471 0,0494 1,2,3,4,7,8,9-Heptachlorodibenzofuran ng/kg dry wt 0,0263 0,015 < 0,011 0,024 < 0,017 < 0,023 < 0,0098 0,0122 1,2,3,4,7,8-Hexachlorodibenzofuran ng/kg dry wt 0,0436 0,03 0,023 0,051 < 0,03 < 0,017 0,0244 0,0287 1,2,3,6,7,8-Hexachlorodibenzodioxin ng/kg dry wt 0,0389 < 0,01 < 0,022 < 0,028 < 0,055 < 0,045 0,0331 0,0133 1,2,3,6,7,8-Hexachlorodibenzofuran ng/kg dry wt 0,0334 0,019 < 0,013 0,033 < 0,03 < 0,017 0,0155 0,0106 1,2,3,7,8,9-Hexachlorodibenzodioxin ng/kg dry wt 0,0237 < 0,01 < 0,022 < 0,027 < 0,054 < 0,045 0,0663 0,0138 1,2,3,7,8,9-Hexachlorodibenzofuran ng/kg dry wt < 0,0133 < 0,008 < 0,015 < 0,027 < 0,032 < 0,02 < 0,0125 < 0,0047 2,3,4,6,7,8-Hexachlorodibenzofuran ng/kg dry wt 0,026 0,01 < 0,014 < 0,026 < 0,031 < 0,017 < 0,012 0,008 1,2,3,7,8-Pentachlorodibenzodioxin ng/kg dry wt 0,0176 0,014 0,03 0,051 < 0,03 < 0,026 0,0716 0,0184 1,2,3,7,8-Pentachlorodibenzofuran ng/kg dry wt 0,0277 0,019 0,015 < 0,032 < 0,023 0,016 0,017 0,023 2,3,4,6,7,8-Pentachlorodibenzofuran ng/kg dry wt 0,0318 0,028 0,027 0,06 0,035 0,022 0,0292 0,0308 1,2,3,4,7,8-Hexachlorodibenzodioxin ng/kg dry wt < 0,0114 < 0,01 < 0,022 < 0,026 < 0,052 < 0,043 < 0,0137 < 0,01 2,3,7,8-Tetrachlorodibenzodioxin ng/kg dry wt 0,0217 < 0,005 < 0,011 0,027 < 0,019 < 0,018 0,0502 0,0114 2,3,7,8-Tetrachlorodibenzofuran ng/kg dry wt 0,0489 0,035 0,041 0,063 0,051 0,033 0,0396 0,0799 Octachlorodibenzodioxin ng/kg dry wt 0,0483 0,195 0,463 0,885 0,535 0,231 0,3428 0,2255 Octachlorodibenzofuran ng/kg dry wt 0,1664 0,061 0,123 0,097 0,129 0,078 0,0601 0,0481 PCBs below the LOQ Contents All the biochars are below limits defined by 3 guidelines and 1 french regulation Fluxes Below limits defined by french regulation RCR < 2 for all POP in Biochars

10 Ecotoxicological risk assessment

11 Global approach - Soil improver ISO : Effects of contaminated soils on the emergence and early growth of higher plants Biochars tested : D1-BC ; D2-BC ; PmW-BC Plant test : barley (Hordeum vulgare) and cress (Lepidium sativum) Application doses : t dw/ha Emergence 7 days after seedling Dry weight 14 days after 70% emergence of the seedling in the control group Emergence and biomasses are compared to those of untreated control plants and percentage of inhibition are calculated Toxicity threshold : 25 % inhibition

Global approach - Soil improver ISO 11-269-2 :

12 Global approach - Soil improver ISO : Effects of contaminated soils on the emergence and early growth of higher plants No negative impact at 1, 5 and 10 t/ha ; At 50 t/ha, only on cress emergence

13 Global approach - Soil improver ISO : Determination of effects on reproduction of Eisenia fetida/eisenia andrei Biochars tested : D1-BC ; D2-BC ; PmW-BC Test indicators : Eisenia fetida and Eisenia andrei Application doses : t dw/ha Mortality and biomasses of adults eartworms 28 days after exposure Reproduction (numbers of juvenils) 56 days after exposure Biomasses and numbers of juvenils are compared to those of untreated control and expressed as inhibition percentage Toxicity threshold : 20 % inhibiton for biomasses 50 % inhibition for numbers of juvenils

14 Global approach - Soil improver ISO : Determination of effects on reproduction of Eisenia fetida/eisenia andrei % Mortality after 28 days Doses D1-BC D2-BC PmW-BC Dose Dose Dose Dose Control No negative impact at 1, 5, 10 and 50 t/ha

15 Global approach - Component growing media ISO : Effects of contaminated soils on the emergence and early growth of higher plants Biochar tested : W1-BC Plant test : barley (Hordeum vulgare) and cress (Lepidium sativum) Application doses : % (volum/volum) Emergence 7 days after seedling Dry weight 14 days after 70% emergence of the seedling in the control group Emergence and biomasses are compared to those of untreated control plants and percentage of inhibition are calculated Toxicity threshold : 25 % inhibition

16 Global approach - Component growing media ISO : Effects of contaminated soils on the emergence and early growth of higher plants No negative impact on emergence No negative impact on barley growth Cress growth Dose 10% (v/v) : - 47% growth Dose 20% (v/v) : - 54% growth

Global approach - Component growing media ISO 11-268-2 : Determination of effects on reproduction of Eisenia fetida/eisenia andrei Biochars tested :

adults eartworms 28 days after exposure Reproduction (numbers of juvenils) 56 days after exposure Biomasses and numbers of juvenils are compared to

17 Global approach - Component growing media ISO : Determination of effects on reproduction of Eisenia fetida/eisenia andrei Biochars tested : D1-BC ; D2-BC ; W1-BC Test indicator : Eisenia fetida and Eisenia andrei Application doses : % (volum/volum) Mortality and biomasses of adults eartworms 28 days after exposure Reproduction (numbers of juvenils) 56 days after exposure Biomasses and numbers of juvenils are compared to those of untreated control and expressed as inhibition percentage Toxicity threshold : 20 % inhibition for biomasses 50 % inhibition for numbers of juvenils

Global approach - Component growing media ISO 11-268-2 : Determination of effects on reproduction of Eisenia fetida/eisenia andrei % Mortality after 28 days Doses D1-BC

18 Global approach - Component growing media ISO : Determination of effects on reproduction of Eisenia fetida/eisenia andrei % Mortality after 28 days Doses D1-BC D2-BC W1-BC Dose 5% Dose 10% Dose 20% Control Negative impact at all application doses - High mortality rate - Biomass loss - No reproduction

19 Ecotoxicological risk assessment

Leaching Batch Leaching (EN ISO TS 21268-2 ) Upward Leaching (EN ISO TS 21268-3 )

hours agitation at 10 rpm Liquid/Solid (L/S) Ratio = 10 3,5 kg dw soil + 6g dw Biochar

Liquid/Solid Ratio L/kg Volume of eluate L Eluate 1 0,1 ± 0,02 0,367 Eluate 2 0,1 ±

Eluate 6 3,0 ± 0,2 11,01 Eluate 7 5,0 ± 0,2 18,349 L/S Ratio = 10 2,5 kg dw soil +

20 Leaching Batch Leaching (EN ISO TS ) Upward Leaching (EN ISO TS ) Downward Leaching (Lysimetric essay) 90g dw Biochar 900ml lixiviant (CaCl 2 1mM) 24 hours agitation at 10 rpm Liquid/Solid (L/S) Ratio = 10 3,5 kg dw soil + 6g dw Biochar (dose soil improver: 5 t dw/ha) Lixiviant (CaCl 2 1mM) Upward flow = 49 ml/hours Liquid/Solid Ratio L/kg Volume of eluate L Eluate 1 0,1 ± 0,02 0,367 Eluate 2 0,1 ± 0,02 0,367 Eluate 3 0,3 ± 0,05 1,101 Eluate 4 0,5 ± 0,01 1,835 Eluate 5 1,0 ± 0,2 3,67 Eluate 6 3,0 ± 0,2 11,01 Eluate 7 5,0 ± 0,2 18,349 L/S Ratio = 10 2,5 kg dw soil + 3,25g dw Biochar (dose soil improver) 600 ml watering: rainfall episode simulation 80mm L/S Ratio = 0,25

21 Potential Toxic Elements 1) Analysis of heavy metals concentration in aqueous extract Arsenic (As), Cadmium (Cd), Chromium (Cr), Copper (Cu), Mercury (Hg), Molybdenum (Mo), Nickel (Ni), Lead (Pb), Selenium (Se), Zinc (Zn) 2) Calculation of efficiency of extraction for each metals quantity biochar x heavy metal content x concentration 3) Evaluation of Predicted Environmental Concentration (PEC) in 2 compartments Infiltration of surface water in groundwater (50%) and in river (50%) 5 tons dw/ha x heavy metal content x efficiency of extraction Groundwater Daily flow : 540 m 3 Annual flow : m 3 River Daily flow : m 3 Annual flow : m 3 Stormy episode during 24 hours Rain during 1 year 4) Calculation of Risk Characterization Ratio (RCR)

22 Batch leaching 6 Biochars Potential Toxic Elements RCR River Rain during 1 year RCR Groundwater PNEC PTE mg/l D1-BC D2-BC D3-BC W2-BC WC-BXC Pig-BC D1-BC D2-BC D3-BC W2-BC WC-BXC Pig-BC As 0, Cd 0, ,000 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,000 Cr 0,0041 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,000 Cu 0,0016 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,001 0,000 0,000 0,026 Hg 0, Ni 0,0005 0,000 0,000 0,000 0,000 0,000 0,000 0,004 0,000 0,000 0,000 0,000 0,004 Pb 0,005 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,000 Se 0, Zn 0,0086 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,000 0,001 0,000 0,001 RCR River Stormy episode during 24 hours RCR Groundwater PNEC PTE mg/l D1-BC D2-BC D3-BC W2-BC WC-BXC Pig-BC D1-BC D2-BC D3-BC W2-BC WC-BXC Pig-BC As 0, Cd 0, ,000 0,000 0,000 0,000 0,000 0,000 0,075 0,044 0,022 0,022 0,022 0,022 Cr 0,0041 0,000 0,000 0,000 0,000 0,000 0,000 0,068 0,022 0,008 0,003 0,029 0,008 Cu 0,0016 0,001 0,000 0,002 0,001 0,001 0,060 0,122 0,031 0,278 0,148 0,081 9,549 Hg 0, Ni 0,0005 0,009 0,001 0,001 0,001 0,001 0,009 1,481 0,093 0,093 0,093 0,093 1,389 Pb 0,005 0,000 0,000 0,000 0,000 0,000 0,000 0,030 0,005 0,002 0,005 0,002 0,002 Se 0, Zn 0,0086 0,000 0,001 0,000 0,003 0,000 0,002 0,027 0,108 0,013 0,431 0,065 0,323 RCR > 2 for copper in Pig-BC Confirmed risk in the most critical scenario

Potential Toxic Elements PTE Upward leaching 2 Biochars (D1-BC, D2-BC) Downward leaching 1 Biochar (D1-BC), 2 leachings PNEC mg/l D1-BC Upward Leaching D1-BC Downward Leaching 1 RCR River D1-BC

23 Potential Toxic Elements PTE Upward leaching 2 Biochars (D1-BC, D2-BC) Downward leaching 1 Biochar (D1-BC), 2 leachings PNEC mg/l D1-BC Upward Leaching D1-BC Downward Leaching 1 RCR River D1-BC Downward Leaching 2 Rain during 1 year D2-BC Upward Leaching D1-BC Upward Leaching RCR Groundwater D1-BC Downward Leaching 1 D1-BC Downward Leaching 2 D2-BC Upward Leaching As 0,0044-0, , Cd 0, ,000 0,000 0,000-0,006 0,002 0,000 - Cr 0,0041 0,000 0,000 0,000-0,002 0,000 0,000 - Cu 0,0016-0, , Hg 0, ,000 0, ,002 0,000 - Ni 0,0005 0,000 0,000 0,000-0,075 0,008 0,000 - Pb 0,005 0,000 0,000 0,000-0,013 0,000 0,000 - Se 0, ,000 0,000 0,000-0,026 0,001 0,000 - Zn 0,0086-0,000 0, ,007 0,010 - PTE PNEC mg/l D1-BC Upward Leaching Stormy episode during 24 hours RCR River RCR Groundwater D1-BC Downward Leaching 1 D1-BC Downward Leaching 2 D2-BC Upward Leaching D1-BC Upward Leaching D1-BC Downward Leaching 1 D1-BC Downward Leaching 2 D2-BC Upward Leaching As 0,0044-0, , Cd 0, ,014 0,005 0,000-2,242 0,728 0,014 - Cr 0,0041 0,005 0,001 0,000-0,727 0,093 0,004 - Cu 0,0016-0, , Hg 0, ,004 0, ,637 0,012 - Ni 0,0005 0,171 0,019 0,000-27,307 3,058 0,059 - Pb 0,005 0,029 0,000 0,000-4,614 0,076 0,001 - Se 0, ,060 0,003 0,000-9,541 0,434 0,008 - Zn 0,0086-0,017 0, ,667 3,740 - Upward leaching L/S = 10 Downward leaching L/S = 0,25 RCR > 2 for several heavy metals Confirmed risk in the most critical scenario

24 Ecotoxicological risk assessment

indicator : Pseudokirchneriella subcapitata Tested doses : range of concentration of aqueous extract Growth 72 hours after

25 Global approach ISO 8692 : Fresh water algal growth inhibition test with unicellular green algae Aqueous extract by : - batch leaching (6 Biochars) - downward leaching (Mix Soil + 1 Biochar) - upward leaching (Mix Soil + 1 Biochar) Test indicator : Pseudokirchneriella subcapitata Tested doses : range of concentration of aqueous extract Growth 72 hours after exposure Growth are compared to those of untreated control and percentage of inhibition are calculated Toxicity threshold : 15 % inhibition

Global approach ISO 6341: Determination of the inhibition of the mobility of Daphnia

(Mix Soil + 1 Biochar) - upward leaching (Mix Soil + 1 Biochar) Test indicator :

26 Global approach ISO 6341: Determination of the inhibition of the mobility of Daphnia magna Straus Aqueous extract by : - batch leaching (6 Biochars) - downward leaching (Mix Soil + 1 Biochar) - upward leaching (Mix Soil + 1 Biochar) Test indicator : Daphnia magna Straus Tested doses : range of concentration of aqueous extract Immobilization of D. magna after 24 and 48 hours exposure Immobilization are compared to those of untreated control and percentage of inhibition are calculated Toxicity threshold : 20 % inhibition

27 Global approach Aqueous extract by batch leaching Inhibition algae growth: Pig-BC > D1-BC > WC-BCX > D3-BC > D2-BC > W2-BC Inhibition daphnia mobility: Pig-BC > D1-BC > D2-BC > D3-BC > WC-BCX > W2-BC

28 Global approach Aqueous extract by downward leaching Inhibition algae growth: No ecotoxicity for D1-BC leaching, soil leaching present more effect! Inhibition daphnia mobility: No ecotoxicity

29 Global approach Aqueous extract by upward leaching Inhibition algae growth: No ecotoxicity for soil and mix soil + D1-BC Inhibition daphnia mobility: No ecotoxicity

Conclusion Terrestrial Risks - Particular attention should be given to heavy metals content in feedstocks - Use as soil improver : No risks are identified on tested indicators at 5 and 10 tons dw/ha

30 Conclusion Terrestrial Risks - Particular attention should be given to heavy metals content in feedstocks - Use as soil improver : No risks are identified on tested indicators at 5 and 10 tons dw/ha PTE : confirmed risk in the most critical scenario : «Terms of use» should be defined - Use as growing media component : confirmed risk starts at dose 5 % (v/v) Aquatic Risks - Particular attention should be given to heavy metals content in feedstocks - Confirmed risk in the most critical scenario : «Terms of use» should be defined - Aqueous extracts from batch leaching : confirmed effects are identified Coloration of extract inhibits growth? tests on other indicators? - Aqueous extracs from up/down leaching : no risks are identified on tested indicators Biochars should not present an ecotoxic risk in defined usage

31 Thank you for your attention

Biochar: Contaminant source or sink?

Federal Department of Economic Affairs FDEA Agroscope ReckenholzTänikon Research Station ART Biochar: Contaminant source or sink? Isabel Hilber, Franziska Blum, Hans Peter Schmidt, Sarah Hale, Gerard Cornelissen,