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Advisor(s)
Abstract(s)
Polyaromatic hydrocarbon (PAH) sorption
to soil is a key process deciding the transport and fate
of PAH, and potential toxic impacts in the soil and
groundwater ecosystems, for example in connection
with atmospheric PAH deposition on soils. There are
numerous studies on PAH sorption in relatively low
organic porous media such as urban soils and groundwater
sediments, but less attention has been given to
cultivated soils. In this study, the phenanthrene partition
coefficient, KD (liter per kilogram), was measured
on 143 cultivated Danish soils (115 topsoils, 0–0.25-m
soil depth and 28 subsoils, 0.25–1-m depth) by the
single-point adsorption method. The organic carbon
partition coefficient, KOC (liter per kilogram) for
topsoils was found generally to fall between the KOC
values estimated by the two most frequently used
models for PAH partitioning, the Abdul et al.
(Hazardous Waste & Hazardous Materials 4(3):211–
222, 1987) model and Karickhoff et al. (Water
Research 13:241–248, 1979) model. A less-recognized
model by Karickhoff (Chemosphere 10:833–846,
1981), yielding a KOC of 14,918 Lkg−1, closely
corresponded to the average measured KOC value for
the topsoils, and this model is therefore recommended
for prediction of phenanthrene mobility in cultivated
topsoils. For lower subsoils (0.25–1-m depth), the KOC
values were closer to and mostly below the estimate by
the Abdul et al. (Hazardous Waste & Hazardous
Materials 4(3):211–222, 1987) model. This implies a
different organic matter composition and higher PAH
sorption strength in cultivated topsoils, likely due to
management effects including more rapid carbon turnover.
Finally, we applied the recent Dexter et al.
(Geoderma 144:620–627, 2008) theorem, and calculated
the complexed organic carbon and non-complexed
organic carbon fractions (COC and NCOC, grams per
gram). Multiple regression analyses showed that the
NCOC-based phenanthrene partition coefficient
(KNCOC) could be markedly higher than the COCbased
partition coefficient (KCOC) for soils with a
clay/OC ratio <10. This possibly higher PAH sorption
affinity to the NCOC fraction needs further investigations
to develop more realistic and accurate models for
PAH mobility and effects in the environment, also with
regard to colloid-facilitated PAH transport.
Description
Keywords
Phenanthrene PAH Sorption Organic carbon Agricultural soils
Citation
Publisher
Springer Netherlands