Environ Sci Pollut Res 
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Fig. 9 Risk assessment of the 
median concentrations of the 
detected micropollutants in the 
Baltic Sea from 2001 to 2014. 
Risk quotient <0.1 low risk; 0.1 < 
risk quotient < 1 medium risk; 1 < 
risk quotient high risk. Data: see 
Tab. S14 
(German Bight 1.9 ng/L, Baltic Sea 1.1 ng/L) followed by ISO 
and CHLO (Fig. 8, Tab. S13). In the group of phenoxyacetic 
acid herbicides, significant differences are shown. 2,4-D is the 
dominant herbicide (1.8 ng/L) in the Baltic Sea, but concen 
trations are low in the German Bight (0.2 ng/L) (Fig. 8, Tab. 
S13). In contrast, MCPP concentrations are much higher in 
the German Bight than in the Baltic Sea (0.7 ng/L and 0.15 ng/ 
L, respectively). MCPA and DCPP occurrences are similar in 
both seas (Tab. S13). Among the other herbicides, CHL 
shows remarkably higher levels in the Baltic Sea, with a me 
dian concentration of 3.2 ng/L compared to 0.5 ng/L in the 
German Bight (Fig. 8, Tab. S13). For all other herbicides, 
higher concentrations were observed in the German Bight 
(Tab. S13). 
Though the high ATR and SIM concentrations can be ex 
plained, by an old burden and the limited water exchange of 
the Baltic Sea, the reasons for the other observed differences 
in the compound patterns are less distinct. Differences can 
arise by the different main sampling periods as the Baltic 
Sea was mainly monitored in winter, whereas the German 
Bight was sampled during summer (Loewe 2009; Theobald 
et al. 2011; Loewe et al. 2013). Flowever, differences in her 
bicide application can be a cause as well, due to historic, 
economic, or agricultural (crop cultivation) reasons. The low 
er general concentrations can be explained by the lack of large 
river input, as in the case of the German Bight (e.g., Elbe, 
Rhine). Because of this, the much lower concentrations of 
BENZTRI and CARB can be explained. Both are discharged 
by the Odra, but the main freshwater stream is directed to the 
east and does not influence most of the monitoring stations. 
For the PFASs, the Odra is no significant input source. As 
shown in the “Long-time trends” section, some herbicides in 
fact show seasonal dependence and higher concentrations dur 
ing the summer, e.g., DIU and 2,4-D. This can explain the 
lower values because of leveling effect, due to their 
application periods, of the winter sampling campaigns. 
Although, this does not explain the observed different pat 
terns; high 2,4-D and CEIL, but low TERB. 
Ecological evaluation and risk assessment 
Even though the observed concentrations of the determined 
micropollutants might appear to be relatively low, they do 
increase the pollution of the Baltic Sea. As there are not yet 
reliable eco-toxicological data available for most of the inves 
tigated compounds, it is difficult to assess the ecological ef 
fects of the detected micropollutants in the Baltic Sea. Despite 
that, a first step was conducted to evaluate the potential risk of 
occurring micropollutants. For the risk assessment, a risk quo 
tient is calculated as a ratio of the measured environmental 
concentration and the predicted no-effect concentration 
(PNEC). For each micropollutant, a risk quotient was calcu 
lated by either using a known marine water PNEC or a sensi 
tive freshwater PNEC (Tab. S14) (Ferrari et al. 2004; 
European Commission 2005c, a, b; Munoz et al. 2010; 
Mhadhbi et al. 2012; Ccanccapa et al. 2016; NORMAN 
Network March 2020). 
Most micropollutants show low risk (risk quotient < 0.1) 
and do not pose acute toxic effects, except for two 
micropollutants (Fig. 9). IRG could potentially pose a medium 
risk, whereas for carbendazim (CARBEND), a high risk was 
calculated for the Baltic Sea. CARBEND was only measured 
since 2013 at a median concentration of 1.0 ng/L (;? = 19). Yet, 
the organism Daphnia magna is very sensitive to this fungi 
cide, explaining the high-risk quotient (Ccanccapa et al. 
2016). Thus, future research programs in the Baltic Sea should 
investigate the occurrence and effects of C ARBEND. 
Of more importance are potential additive and cumulative 
effects by a set of pollutants and especially possible chronic 
effects of the pollutant load on aquatic organisms (Magnusson