Environ Sci Pollut Res 
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Fig. 5 The median concentration of selected compounds for winter (W, full-colored column) and summer (S, stripped column) cruises. Data: see Tab. S8 
period as well (Fig. 5). The high summer concentrations for 
PFOA, PFOS-1, and ATR at PB1-3, shown in Tab. S8, should 
be interpreted with precaution as they are statistically of low 
relevance (only one cruise). Flowever, for most herbicides, on 
average, high spatial variations are observed in summer. 
Especially, DIU and Irgarol (IRG) exhibit high hot spots at 
the western coastal stations (KB2, MB1, Tab. S8). Even 
though DIU is prohibited as a pesticide, in Germany since 
2009, it is still used as a biocide and was detectable in the 
marine environment during the winter cruises (2009-2014) 
(European Commission 2007). Other herbicides (ISO, 
MCPA, TERB) show elevated concentrations at the western 
stations as well, but to a much smaller extent (Tab. S8). For 
TERB, it was reported that its occurrence is of high spatial and 
temporal variability (Orlikowska et al. 2015). Thus, for most 
herbicides, more or less pronounced concentration gradients 
can be observed during summer from west to east. 
In contrast, 2,4-D shows high summer concentrations at the 
eastern stations, starting at DZ1 and TF030 (north of the 
Darss) and peaking at the Arkona Basin (TF113 and 
TF109). 2,4-D shows high concentrations at the Odra near 
station PB1-3. Another compound with large input from the 
Odra is CARB (PB1-3, 7.2-12.2 ng/L), despite that it does not 
show elevated concentrations at the Arkona Basin (TF109, 
1.6-2.3 ng/L, Fig. 5, Tab. S7). In 2013, Bjorlenius et al. 
(2018) conducted widespread pharmaceutical screening in 
Baltic Sea coastal waters. The detected CARB concentrations 
during this study are in similar range (2.5-9.1 ng/L, 2.1-3.3 
ng/L, respectively) as station PB1-3 and TF109. Furthermore, 
the study presented a similar decrease from the near coastal 
water in the Odra Bay towards the Arkona Basin. ISO and 
TERB show elevated concentrations at PB1-3 to a medium 
extent (Tab. S8). For most other compounds, the Odra input 
seems to be less pronounced. 
Spatial distribution in the central and eastern Baltic 
Sea 
The station net, sampled during the MM0803 cruise, allowed 
the investigation of the occurrence of the determined com 
pounds in the central and eastern part of the Baltic Sea (parts 
of the PFAS data has been published by Kirchgeorg et al. 
(2010)). The median results are displayed in Fig. 6a, b (data; 
Tab. S9). Most of the prominent compoimds were detected in 
the east, at concentrations similar to the western and central 
part of the Baltic Sea (median east 10.7 ng/L (n = 15), median 
west 10.0 ng/L (;? = 25), Tab. S9, east-west split at N 16° 30' 
0"). Thus, there is a fairly homogenous distribution of 
micropollutants in the Baltic Sea, although the concentration 
range in the west is higher than in the east (west 5.9-27.4 ng/ 
L, east 5.9-12.9 ng/L, Tab. S9). At the eastern edge of the 
survey area, the concentrations split into lower concentrations 
at the northern stations of the Bothnian Sea (GB2 and GB3), 
and higher concentrations at the southern stations of the outer 
GulfofFinland (GF4 and NG3-4) (Fig. 6a). The degree ofthis 
“splitting” is different for the various micropollutants. In the 
western part of the Baltic Sea, the three most dominating 
compoimds are DIU, 2,4-D, and ATR, whereas, in the eastern 
part, ATR, MCPA, and 2,4-D are the more dominating com 
pounds, but at a marginally lower level. 
A homogenous distribution, with gradually declining con 
centrations from west to north-east, is observed for PFOA. No 
significant variability, for the Gulf of Finland and only a small 
decrease for the Bothnian Sea, was identified (Fig. 6a). The 
detected concentrations of PFASs, during the MM0308, are in 
a similar range as published PFAS concentrations by 
Kirchgeorg et al. (2010) for the same year (Tab. S15). 
Similar distributions are encountered for PFOS and ISO 
(Fig. 6a, b. Tab. S9). ISO was increased up to 4.0 ng/L only