Supporting Information Section. Title: Abiotic and microbial oxidation of laboratory-produced black carbon (biochar)

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1 Supprting Infrmatin Sectin Title: Aitic and micrial xidatin f laratry-prduced lack carn (ichar) Authr: Andrew R. Zimmerman, University f Flrida, Department f Gelgical Sciences Jurnal: Envirnmnetal Science & Technlgy Prepared: Decemer 0, pages figure 6 tales SI-

2 SI-2

3 Additinal Methd Infrmatin Specific Surface Area was determined using th N 2 and O 2 adsrptin n a Quantachrme Autsr. External surface area, which includes pres >.5 nm was calculated using multipint adsrptin data frm the linear segment (in partial pressur range f 0.00 t 0.03) f the N 2 adsrptin istherms (at 77 K) using Brunauer-Emmett-Teller (BET: Brunauer et al., 938) thery. Pre size distriutins were calculated frm desrptin ranch istherms using the Barrett-Jyner-Halenda (BJH) thery (Barrett et al., 95). Internal surface area and pre vlume fr pres <.5 nm were determined using O 2 adsrptin istherms (at 273 K) generated in the partial pressure range <0.02. These istherms, which cnstitute the s-called kernel, are interpreted using Grand annical Mnte arl (GM) simulatins r the Nn-Lcal Density Functinal Thery (NLDFT). All B samples were de-gassed under vacuum at 200 fr at least 24 hurs prir t analysis. Elemental, N and H aundances were determined n a arl-era NA-500 NS Elemental Analyzer. After grinding in a silica mrtar and pestle, ichar amunts f aut 6 mg fr H and N and aut 0.5 mg fr were weighed int tin capsules. Samples were flash-cmusted in a quartz clumn cntaining chrmium xide and silvered caltus/caltic xide at 000 in an xygen-rich atmsphere. The sample gas is then carried in a He carrier stream thrugh a ht reductin clumn (650 ) cnsisting f reduced elemental cpper t remve xygen and cnvert NO x t N 2. The effluent stream then passes thrugh a chemical (magnesium perchlrate) trap t remve water. The stream then passes thrugh a.5 meter gas chrmatgraphic clumn at 55 that separates the N 2, H 2 and O 2 gases efre detectin y thermal cnductivity. Oxygen cntent was calculated y difference assuming a cmpsitin f, N, H, and O, nly. This assumptin culd have led t an ver-estimate f xygen cntent. If ash cntent (elw) is assumed t represent inrganic elemental weight %, xygen weight% can e re-calculated as - 0% less fr mst samples. Fr Oak650, fr an ash cntent f 3.7%, xygen weight% wuld e 20.4% less and the grasses, with ash cntents ranging 7-25% wuld have re-calculated xygen weight% that are 6-50% less. Vlatile matter and ash cntent was determined using a slightly mdified versin f ASTM methd (D ). Aut 0 mg f nn-grund ichar that had een kept in a drying ven fr at least 2 hrs at 00 and allwed t cl in a desiccatr was weighed int pre-weighed SI-3

4 ceramic cruciles. Vlatile matter cntent was determined as weight lss after cmustin with a lse ceramic cap at fr 6 min. (set-pint was 900 ut sme cling ccurred while ven dr was pen). Ash cntent was determined as weight lss after cmustin at 750 fr 6 h with n ceramic cap. Sample weight was taken after cling in a desiccatr fr h. Vlatile was determined y mass alance fllwing analysis f the cntent f the grund nn-vlatile residue (as ave). SI-4

5 Slutin fr ichar degradatin equatin NOTE: This slutin can e applied nly when the slpe, m > - ecause f mathematical restrictins. Using the equatin fr first rder degradatin, change in amunt f carn,, ver time, t is: d = k () dt where is the initial present and k is the apparent degradatin rate cnstant. Als, k was fund t vary with time such that: ( k ) = mln( t) + ln (2) where m is slpe and is the intercept when fitted t a line using least squares technique. Re-arranging eq. 2, m k = e t (3) and sustituting eq. 3 int eq. yields: d dt = e t m (4) Nw, integrating eq. 4 frm time = 0 t time t, yields: t = ( e ) t m + + K where t is carn present at time t and K is the integratin cnstant. When t = 0, = K, s lst at any time t can e written as: (5) e lst = t = ( ) t (6) T calculate ichar half-life At the half-life: = t t = r / 2 2 Re-arranging eq. 6: t = (7) 2 SI-5

6 t = e (- t + m ) Sustituting eq. 7 int eq. 8 and re-arranging: (8) ( ) = ( ) t (9) / 2 2e Alternate slutin fr ichar lss equatin NOTE: When m < -, the ave equatin is nt slvale s it is necessary t integrate chsing the initial time, t, t e smething greater than zer (0.0 y, fr example). One can view this as necessary, in physical terms, ecause the equatin predicts physically unreasnale large decay rates at times appraching zer. Hwever, still, a carn half life cannt e calculated ecause degradatin rate diminishes s rapidly that the amunt f carn remaining, t, ecmes asympttic with sme value f carn greater than half the initial amunt. Integrating eq. 4 (ave) frm a time f t t t yields: t = ( e ) t + ( e ) t + S lst at any time, t, can e written as: (0) lst = t = ( e m + )( + m t t ) () Alternate slutin fr ichar lss equatin fr special case f when m = - When m = -, can integrate eq. 4 frm time = t t. = e ln( t) + t (2) Then lst is: lss = e ln( t) (3) SI-6

7 Tale S. hemical and physical characteristics f ichars Bimass/har T. O 2. O% Yield Vlatile Vlatile Ash S.A.-N 2 S.A.-O 2 (wgt.%) (wgt.%) (wgt.%) (wgt.%) (wgt.%) (wgt.%) (m 2 /g) (m 2 /g) Buinga (parent) 46. Buinga Buinga Buinga Buinga edar (parent) 47. edar edar edar edar G. Grass (parent) 4.0 G. Grass G. Grass G. Grass G. Grass L. Oak (parent) 44.5 L. Oak L. Oak L. Oak L. Oak L. Pine (parent) 45.4 L. Pine L. Pine L. Pine L. Pine Sug. n. Bag. (parent) 45.2 Sug. n. Bag Sug. n. Bag Sug. n. Bag Sug. n. Bag L. Oak 400_72hrs nd L. Oak 650_72hrs nd L. Pine 400_72hrs L. Pine 650_72hrs Additinal details n plant type descried in text. Peak temperature f cmustin held at 3 h unless specified therwise 2. O = rganic carn cntent, O is xygen cntent, yield = weight ichar/parent imass, vlatile is mass vlatized after 6 min at 900, ash is residual weight after cmustin at 750 fr 6 h, S.A.-N 2 and S.A.-O 2 is surface area determined y N 2 and O 2 adsrptin, respectively, nd = nt determined. SI-7

8 Tale S2. Micrially inculated and aitic carn mineralized during ne year incuatins (char weight-nrmalized: mg g - ) f ichars made frm different parent imass types and cmustin temperatures (as shwn in Figure 2 r manuscript) itic aitic itic aitic itic aitic itic aitic itic aitic Parent Oak 4. ± ± 4 ±.3 6. ± ± ± ± ± ± ± 0.2 Pine 8.0 ± ± ± ± ± ± ± ± ± ± 0.2 edar 3.0 ± ± ± ± ± ± ± ± 0.4 n.d. n.d. Buinga 8.9 ± ± ± ± 0.5 n.d. 4.7 ± ± ± 0.4 n.d. n.d. Gamma grass 6.2 ± ± ±..7 ± ± ± ± ± 0.3 n.d. n.d. Sugar ane 9.8 ± ± ± ± ± ± ± ± 0.5 n.d. n.d. SI-8

9 Tale S3. Micrially inculated and aitic carn mineralized during ne year incuatins (char -nrmalized: mg g - ) f ichars made frm different parent imass types and cmustin temperatures (as shwn in Figure 2 r manuscript) itic aitic itic aitic itic aitic itic aitic itic aitic Parent Oak 22.5 ±. 3.4 ± ±.9 9. ± ± ± ± ± ± ± 0.2 Pine 29.3 ± ±.5.2 ± ± ± ± ± ± ± ± 0.2 edar 2.8 ± ± ± ± ± ± ± ± 0.4 n.d. n.d. Buinga 4.4 ± ± ± ± 0.6 n.d. 5.5 ± ± ± 0.5 n.d. n.d. Gamma grass 2.5 ± ± ± ± ± ±. 2.5 ± ± 0.5 n.d. n.d. Sugar ane 7.4 ± ± ± ± ± ± ± ± 0.7 n.d. n.d. SI-9

10 Tale S4. Significant relatinships etween ichar mineralizatin rate and chemical and physical characteristics f ichars Mdeled aitic % lst 00 y Measured Measured tt. min. tt. aitic min. (mg/g char-y) (mg/g char-y) S.A.-N 2 (m 2 /g) S.A.-O 2 (m 2 /g) O (wght.%) O (wght.%) Yield (wght.%) Vlatile matter (wght.%) Vlatile arn (wght.%) Mdeled % lst -00 y Mdeled aitic % lst -00 y Measured tt. min. (mg /g char-y) Measured tt. aitic min. (mg /g char-y) S.A.-N 2 m 2 /g S.A.-O 2 m 2 /g O (wght.%) O (wght.%) Yield (wght.%) Vlatile matter (wght.%) n.s n.s n.s n.s n.s n.s Areviatin same as Tale S. 2. rrelatin cefficient (r 2 ) fr linear significant (i.e. p > 0.05) relatinship etween tw variales; underlined when relatinship is indirect, n.s. = relatinship nt significant at 95% level. SI-0

11 Tale S5. Degradatin parameters fr ttal (itic + aitic) mineralizatin Bichar Linear Parameters (ln k vs. ln t) Mdeled Degradatin Parameters Parent must Size 2 r. ef. slpe intercept Bimass Temp (r 2 ) t /2 % lst 00 y MRT 3 00 y % lst ky MRT 3 ky Buinga 250 cs , Buinga 400 cs , Buinga 650 cs , edar 250 cs edar 400 cs , edar 400 fn , edar 525 cs , edar 525 fn , edar 650 cs E Grass 250 cs Grass 400 cs Grass 525 cs Grass 650 cs Oak 250 cs Oak 250 fn Oak 400 cs , Oak 525 cs , Oak 525 fn E Oak 650 cs , Oak 650 fn , Pine 250 cs a Pine 400 cs Pine 525 cs , Pine 525 fn , Pine 650 cs , Pine 650 fn , Sugane 250 cs Sugane 400 cs , SI-

12 Sugane 525 cs , Sugane 650 cs , Oak h cs , Oak h cs E Pine h cs , Pine h cs , Ntes. When ln(k) in units f y - and ln(t) are in units f y 2. s = carse ( µm), fn = fine (<250 µm) 3. MRT = Instantaneus mean residence time fr the time given (in y), calculated as the inverse f the degradatin cnstant k. a = cannt e calculated SI-2

13 Tale S6. Degradatin parameters fr aitic mineralizatin Bichar Linear Parameters (ln k vs. ln t) Mdel Degradatin Parameters Parent must Size 2 r. ef. slpe intercept Bimass Temp (r 2 ) t /2 % lst 00 y MRT 3 00 y % lst ky MRT 3 00 y Buinga 250 cs , , ,32 Buinga 400 cs ,88.7, ,395 Buinga 525 cs , , ,32 Buinga 650 cs , , ,824 edar 250 cs , , ,349 edar 400 cs , , ,236 edar 400 fn , , ,677 edar 525 cs E , ,24 edar 525 fn , , ,30 edar 650 cs , , ,098 Grass 250 cs ,974 Grass 400 cs ,644 Grass 525 cs , , ,474 Grass 650 cs , , ,34 Oak 250 cs , , ,877 Oak 250 fn ,644 4., ,527 Oak 400 cs ,558.3, ,693 Oak 525 cs , , ,597 Oak 525 fn , ,239 Oak 650 cs , , ,394 Oak 650 fn , ,30 Pine 250 cs ,323 3., ,730 Pine 400 cs Pine 525 cs a ,890..E+06 Pine 525 fn Pine 650 cs E , ,293 Pine 650 fn , , ,279 Sugane 250 cs ,00 SI-3

14 Sugane 400 cs , , ,042 Sugane 525 cs , , ,00 Oak h cs E , ,530 Ntes same as Sup. Tale 3 SI-4

15 Figure S. Linear relatinship etween ichar lst after 00 y (mdeled using data frm f micrially-inculated incuatins f carse-grained ichar; mm) and vlatile carn cntent (determined as weight lss after cmustin at fr 6 min.). SI-5