Journal
CHEMOSPHERE
Volume 174, Issue -, Pages 700-707Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.chemosphere.2017.02.014
Keywords
Organic pollutants; Agricultural practice; Biochar as feed additive; Biochar mixtures; Post-processing
Categories
Funding
- Polish-Swiss Research Programme [PSPB-135/2010]
- Swiss Contribution to the enlarged European Union
- MACATA project (Austria)
- Norwegian Research Council through a FriPro free project [217918]
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Bioaccessibility data of PAHs from biochar produced under real world conditions is scarce and the influence of feedstock and various post-pyrolysis treatments common in agriculture, such as co composting or lacto-fermentation to produce silage fodder, on their bioavailability and bioaccessibility has hardly been studied. The total (C-total), and freely dissolved (i.e., bioavailable) concentrations (C-free) of the sum of 16 US EPA PAHs of 43 biochar samples produced and treated in such ways ranged from 0.4 to almost 2000 mg/kg, and from 12 to 81 ng/L, respectively, which resulted in very high biochar-water partition coefficients (4.2 < log K-D < 8.8 L/kg) for individual PAHs. Thirty three samples were incubated in contaminant traps that combined a diffusive carrier and a sorptive sink. Incubations yielded samples only containing desorption-resistant PAHs (C-res). The desorption resistant PAH fraction was dominant, since only eight out of 33 biochar samples showed statistically significant bioaccessible fractions (f(bioaccessible) = 1 - C-res/C-total). Bioavailability correlated positively with C-total/surface area. Other relationships of bioavailability and accessibility with the investigated post-pyrolysis processes or elemental composition could not be found. PAH exposure was very limited (low C-free, high C-res) for all samples with low to moderate C-total whereas higher exposure was determined in some biochars with C-total > 10 mg/kg. (C) 2017 Elsevier Ltd. All rights reserved.
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