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@PHDTHESIS{Claen:765014,
author = {Claßen, Daniela},
othercontributors = {Schäffer, Andreas and Hollert, Henner},
title = {{S}tudien zum {E}influss einer chemischen {L}adung auf
{S}orption, {S}chicksal und {B}ildung nicht-extrahierbarer
{R}ückstände organischer {C}hemikalien im {B}oden},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
reportid = {RWTH-2019-07191},
pages = {1 Online-Ressource (122 Seiten) : Illustrationen,
Diagramme},
year = {2019},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, RWTH Aachen University, 2019},
abstract = {In the present study we investigated the influence of an
ionic functional group on the sorption, fate and formation
of non-extractable residues of organic compounds in soil.
Using uncharged 4-n-dodecylphenol[phenyl ring-14C(U)]
(14C-DP), negatively charged 4-n-dodecylbenzenesulfonic
acid[phenyl ring-14C(U)] sodium salt (14C-DS-) and
positively charged 4-n-dodecylbenzyltrimethylammonium
chloride[phenyl ring-14C(U)] (14CDA+) with high structural
similarity, we performed sorption tests according to OECD
106 (Adsorption - Desorption using a Batch-Equilibrium
Method) and simulation tests in soil according to OECD 307
(Aerobic and Anaerobic Transformation in Soil) with LUFA
soil 5M. In the sorption tests equilibrium for adsorption
and desorption of 14C-DA+ was reached after 15 and 1680 min
and for 14C-DP and 14C-DS- after 240 min, respectively.
During the sorption test, DP was abiotically degraded to
more polar transformation products. Partitioning
coefficients were therefore determined according to the
amounts of adsorbed and desorbed DP detected by
TLC-Analysis. Sorption kinetic for DS- was linear and the
partitioning coefficients for adsorption and desorption
amounted to logK=2.68 and logK =1.78. Cooperative adsorption
of DP und DA+ was obviously higher (logK>3.30) compared to
14C-DS- and is considered irreversible (logK <0.55).
Experimentally determined logKoc values for 14C-DP, 14C-DS-
and 14C-DA+ were high (>3.0) and deviate from calculated
logKoc in case of the ionic chemicals. Considering the
structural similarity it could be shown that a positive
charge lead to an increased sorption of organic chemicals on
soil. Aim of the simulation test was to investigate the fate
of 14C-DP, 14C-DS- und 14C-DA+ in sterile and non-sterile
soil. After application of the test substances with 1 mg/kg
to sterilized and non-sterilized soil and incubation for 0,
1, 7, 14, 49, 84 and 124 days, samples were sequentially
extracted. Distribution of the applied radioactivity (AR)
among volatile, mineralized, extractable and non-extractable
residues (NER) for 14C-DP, 14C-DS- und 14C-DA+ were
investigated. Extractable portions of 14C were examined by
means of TLC, HPLC and LC-MS/MS analyses. After 124 days of
incubation highest mineralization could be observed for
14C-DS- $(64.5\%$ AR), followed by 14C-DP $(44.0\%$ AR) and
14C-DA+ $(37.8\%$ AR) whereas formation of 14CO2 in sterile
soil was neglectable. In case of 14C-DP und 14C-DS- the rate
of mineralization and the microbial activity (DMSO reduction
rate) in non-sterilized soil simultaneous increased from day
0 until day 14. For 14C-DA+ the mineralization and DMSO
reduction rate were constantly low over time. Extractable
radioactivity for 4C-DA+ amounted to $18.0\%$ AR, but only
low amounts of 14C-DP und 14C-DS- were extractable form the
soil $(2.7-4.7\%$ AR) at the end of the test. Besides
14C-DP, 14C-DS- and 14C-DA+ polar and nonpolar (14C-DA+)
transformation products were detected in the extracts over
time. Highest amounts of 14C-DP, 14C-DS- and 14C-DA+ were
potentially bioavailable in soil. In the calcium chloride
extracts only transformation products were detected.
Half-life (DT50) decrease in the following manner: DA+(61.70
days)>DS-(18.20 days)>DP(9.96 days). The findings suggest
that a negative and positive charge increases the DT50 of
organic chemicals in soil. Highest amounts of NER at the end
of the tests were observed for 14C-DP $(45.4\%$ AR) followed
by 14C-DA+ $(34.2\%$ AR) and 14C-DS- $(23.1\%$ AR).
Considerable amounts of NER of 14C-DA+ $(16.0\%$ AR) were
formed under sterile soil conditions. NER at day 7 and 84
were further investigated with respect to sequestered,
covalently bound and biogenic residues (NER types I, II, and
III). Silylation of 14C-DP, 14C-DS- and 14C-DA+ derived NER
after 7 and 84 days of incubation released $3.0-23.2\%$ AR,
indicating that these were strongly sorbed or physically
entrapped (type I NER) in the soil. The reminder of the
residues $(12.9-33.1\%$ AR) were covalently bound (type II
NER) to the soil. Analysis of extracts derived by silylation
shows that 14C-DP $(2.3\%$ AR), but neither 14C-DS- nor
14C-DA+ were released by the silylation procedure. This
suggests that only in case of 14C-DP, the parent substance
was part of type I NER, which is considered reversibly bound
to soil. Acid hydrolysis of the 14C-DP, 14C-DS- and 14C-DA+
NER containing soil after 7 and 84 days of incubation and
subsequent analysis of soil extracts regarding
14C-aminoacids (14C-AA) indicates that $2.5-23.8\%$ AR are
biogenically formed residues (type III NER) in soil. Most DP
and DS- derived NER were biogenically or covalently bound,
whereas DA+ predominantly forms sequestered NER in soil.
After re-incubation of the NER containing soil of 14C-DP,
14C-DS- und 14C-DA+ after 7 and 84 days with nonsterilized
soil for 54 days, remobilisation (sum of volatile,
mineralised and extractable residues) amounted to
$7.2-19.1\%$ AR; however, the highest amounts still remained
nonextractable in soil $(16.4-31.2\%$ AR). With regard to
the results it is recommended to use an experimentally
determined logKd instead of calculated/experimental logKoc
values for the assessment of the adsorption of ionic
chemicals in soil in frame of persistence assessment.
Furthermore, chemicals with an obviously high NER formation
should be investigated according to sequestered (type I),
covalently bound (type II) and biogenic (type III) NER. The
formation of type I NER should be taken into account in the
persistence assessment, if the parent substance has been
analytically determined in this fraction. In this case, the
sequestered amount of parent molecule should be included in
the calculation of the DT50. In case that analytical
investigations of type I NER regarding the parent molecule
were technically not feasible, the DT50 has to be calculated
considering the total amount of sequestered (type I) NER in
accordance with the precautionary principle.},
cin = {162710 / 160000},
ddc = {570},
cid = {$I:(DE-82)162710_20140620$ / $I:(DE-82)160000_20140620$},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2019-07191},
url = {https://publications.rwth-aachen.de/record/765014},
}
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