Archives of Environmental Contamination and Toxicology (2022) 82:481—492 
Table 2 Comparison of the observed TCE mass fraction ranges (<20 um grain size fraction) of this study with other environmental sample 
matrices 
This study Ohta et al. (2010) Dolor et al. Lu6Cic et al. Ba6Cic et al. Salminen Rudnick 
(20091 (2021) (2021) et al. and Gao 
(2006)! (2003) 
coastal coastal river UCC 
North a South 
Sc/mg kg”! 8.1-18.1 8.8—18.2 1.56—67 
Y/mg kg”! 11.9-31.5 14.2-316 2.5-34.1 
Ga/mg kg”) 14-23 14-20 2.2-20.9 
Ge/mg kg” 1.4-2.3 1.2-1.9 
Nb/mg kg”! 11.0-15.4 8.0-18.2 0.7-28.4 
In/ug kg”! 73-237 88-170 
La/mg kg”! 18.7-41.9 20.3-58.9 
Ce/mg kg”! 45-88 46—120 
Pr/mg kg”! 6.3-11.0 6.5-14.9 
Nd/mg kg”! 24-40 25-54 
Sm/mg kg”! 5.2-8.6 5.3-10.2 
Eu/mg kg”! 1.08-1.84 1.12-1.78 
Gd/mg kg”! 4.6—7.8 1.5-8.6 
Tb/ug kg” 690-1170 590-1180 
Dy/mg kg”! 4.0-6.9 116.6 
Ho/yug kg” 760-1310 790-1250 
Er/mg kg”! 1.9-3.6 2.2-3.6 
Im/mg kg”! 260-490 270-510 
Yb/mg kg”! 2.0-3.3 183.4 
Lu/pg kg”! 280-500 300-540 
Ta/uıg kg”! 800-1200 700-1400 
2.5-18.9 
4.8—46.2 
324.6 
0.22-2.3 
2.2-20.1 
0.6-15.4 
0.42—41.7 
0.19—19.8 
0.01-1.5 
0.19-17.4 
13.1-14.9 
19-23 
16.8-18.2 
1.3-1.5 
'1-13 
48—64 
28-34 
5667 
7.1 
25-29 
4.0-5.0 
0.9-1.1 
3.743 
600-800 
39 
830 
2A 
300 
1.56-2.36 
260-360 
800-1000 
25.65 
9-20 
1.6-2.2 
7-13 
130-240 
6.3-51.3 
‘2.3106 
L.2-13.5 
553.6 
L.2-12 
0.16—2.5 
3.8511 
130-1700 
3.84-9.1 
160-1800 
0.46—4.9 
70-700 
0.4245 
60-620 
0.44-—42.3 
32.50 
56.60 
LAS 
28.25 
54 
1.01 
5.06 
790 
1,53 
220 
2,67 
1.40 
2,58 
390 
‚010 
'median values — Geochemical atlas of Europe (Salminen et al. 2006) 
33.7 mg kg”! + 1.6 mg kg”! and 45.5 mg kg”! +4.1 mg kg”. 
Reese et al. (2019) also observed elevated mass fractions of 
che REESs La, Ce, Pr, Nd, and Sm in the Elbe estuary and 
attributed this to possible discharges of phosphogypsum in 
the Rhine delta (Reese et al. 2019). Due to the proximity 
of station KS11 to the Elbe estuary, a similar effect may 
be occurring here. The boxplot in Fig. 3e shows that even 
though the mass fractions of station KS11 show a higher 
variation over time, all stations of the South and North 
regions state similar median mass fractions ranging from 
32.6 mg kg”! to 40.6 mg kg”'. In addition, PAAS (post- 
archaean average shale) normalization of the REEs does 
not indicate any anomalies or anthropogenic influences (cf. 
supplemental information Fig. A.1 of two stations from both 
regions showing the PA AS-normalized REE patterns). 
Tantalum 
The Ta mass fraction ranges between 
0.7 mg kg”! +0.4 mg kg”! and 1.4 mg kg! +0.1 mg kg”! for 
all samples. Figure 2f shows the Ta mass fractions for all 
stations over the observed time of ten years. All stations of 
che South and North regions show a homogeneous trend as 
shown in Fig. 3f. The median mass fraction of both regions 
ranges from 0.9 mg kg”! to 1.1 mg kg”!. 
Evaluation of Possible TCE Contamination in North 
Sea Sediments 
In order to preliminary classify the determined TCE mass 
fractions in the North Sea, reference values from other stud- 
ies were compared with the TCE mass fractions determined 
in this study. For an optimal comparison, data from a similar 
matrix and region would be preferable. However, TCE data 
from environmental samples are still scarce. Therefore, mass 
fraction ranges and median values from coastal, riverine, 
and lake sediment (BaCic et al. 2021; Dolor et al. 2009; Ohta 
et al. 2010; Salminen et al. 2006) as well as riparian soil 
‚LuCic et al. 2021), and the respective crustal abundances 
‘Rudnick and Gao 2003) were used. Overall the determined 
2 Springer