Are Natural Chars Important for the Sorption of PAHs?

Rainer Lohmann, Julia Sullivan, Kevyn Bollinger Graduate School of Oceanography, University of Rhode Island Oriole Lake is characterized by frequent natural fires, releasing black carbon (BC), chars and polycyclic aromatic hydrocarbons (PAHs) (e.g.,high PAH concentrations during 1836-1905). In the sediments, PAHs from natural fires (B) are sorbed more strongly than in recent sediments with soot BC (A), probably due to additional adsorption onto fire-produced chars. %OC

%BC

Σ PAHs

Retene

A

19%

0.54%

41

831

B

21%

0.45%

2101

63

C

22%

0.44%

260

410

A

1.0E+06

K d, obs.

Sediments in Oriole Lake (CA)

Soot black carbon needed to explain sorption of PAHs

1:1

1.0E+05

1.0E+04

1905-2007

1.0E+03 1.0E+03

1.0E+04

1.0E+05

1.0E+06

1.0E+07

(n-1) Kd, pred. (focKoc + fBCKBCcdiss )

Additional sorption present – results of natural fireproduced chars?

1.0E+07

1.0E+06

K d, obs.

A Field Study with Lake

1.0E+07

B

1:1

1.0E+05

1.0E+04

1836-1905

1.0E+03 1.0E+03

1.0E+04

1.0E+05

Kd, pred. (focKoc + fBCKBCcdiss

1.0E+06

1.0E+07

(n-1)

)

1.0E+07

Less extra sorption present - degradation of fire-derived chars and PAHs?

1.0E+06

K d, obs.

Are Natural Chars Important for the Sorption of PAHs?

C

1:1

1.0E+05

1.0E+04

1790-1836 1.0E+03

1.0E+03

1.0E+04

1.0E+05

1.0E+06 (n-1)

Kd, pred. (focKoc + fBCKBCcdiss

)

1.0E+07