Sum parameters of presented seven PCBs and three DDTs have a decreasing trend as a result of banning the use of PCBs and DDT’s.
The data of 2002 herring muscle samples indicate decreasing concentration levels with one exception (Hanko area) for two-year old herrings compared to data of 2001 when the sum of seven CBs and three DDTs are used as a basis of comparison.
Results and assessment
Polychlorinated biphenyls (PCBs) and DDT with its’ metabolites have been analysed at specific locations (see the map in the end of the document) from Baltic herring (Clupea harengus) muscle in the open sea areas annually since 1979. Environmental monitoring analysis of those hazardous substances is part of the HELCOM monitoring programme performed in the Finnish Institute of Marine Research. Female herrings, age of two years, have represented selected sampling areas surrounding Finland.
No exceptional events/conditions related to harmful substances occurred during the study period or the sampling of the fish in the Gulf of Finland or in the Gulf of Bothnia. In 2002 the number of two year old herrings was below the needed twelve herrings for organic analysis. Therefore all the available two and three year old herrings were analysed to get the needed minimum twelve individuals altogether. Despite of it, the number of individuals is below twelve in some cases.
Baltic herring samples
Herring muscle tissues were sampled according to COMBINE programme from five study areas. Individual female fishes were collected from the Gulf of Bothnia and the Gulf of Finland (Kalajoki, Pori, Åland, Hanko and Kotka areas) in autumn and they were analysed in the Finnish Institute of Marine Research (FIMR). Herrings of one-year old collected from Hanko area were analysed, too. Age determinations were performed in the Finnish Game and Fisheries Research Institute. Results of p,p’-DDT and its metabolites (p,p’-DDE and p,p’-DDD) as well as seven PCBs (CB28, CB52, CB101, CB118, CB153, CB138 and CB180) are presented in the Tables 1 and 2.
General overviews of the concentrations of DDTs and CBs in different sampling areas around Finland are highlighted in Figures 1, 2 and 3. The data of 2002 herring samples indicate decreasing concentration levels for two-year old herrings compared to data of 2001 herrings based on the sum of seven CBs and three DDTs with one exception (Hanko area). Concentration level of one-year old herrings of Hanko area (n=7) were quite close to sum of CBs and DDTs of Pori area’s two-year old herrings. For one-year old herrings an average sum (n=7) of seven CBs was 2.5 µg/kg (ww) and that of three DDTs was 2.4 µg/kg (ww).
Figure 1a. CBs in two-year old Baltic herring of the Gulf of Bothnia and the Gulf of Finland between 2001-2002.
Figure 1b. DDTs in two-year old Baltic herring of the Gulf of Bothnia and the Gulf of Finland between 2001-2002.
Figure 2a. CBs in three-year old Baltic herrings of the Gulf of Bothnia and the Gulf of Finland between 2001-2002.
Figure 2b. DDTs in three-year old Baltic herrings of the Gulf of Bothnia and the Gulf of Finland between 2001-2002.
Figure 3a. The Baltic herring in 2002: sum of seven CBs as average values for each sampling station and age class.
Figure 3b. The Baltic herring in 2002: sum of three DDTs as average values for each sampling station and age class.
Table 1. Sum of seven CBs (28, 52, 101, 118, 153, 138 and 180) as an average value with standard deviation and relative standard deviation for each sampling area in 2002.
Table 2. Sum of DDTs (p,p’-DDT, p,p’-DDD and p,p’DDE) as an average value with standard deviation and relative standard deviation for each sampling area in 2002.
Some “outlier herrings” were detected during analysis. In Hanko area one of the three-year old herrings had enormous concentrations for p,p’-DDE (about 42 µg/kg ww) and CB138 (about 12 µg/kg ww). All the other contaminants were at the “normal” level compared to the other herrings of that area. Within Kotka area one three-year old herring had high levels of p,p’-DDT (about 33 µg/kg, ww) and p,p-DDD (about 298 µg/kg ww). Again, all the other contaminants were at the “normal” level compared to the other herrings of that age. Those huge values were out of the calibration range in the GC-analysis – therefore the values are good estimates. Dilutions of those samples were reanalysed – results were still on that high level. Those outliers were not included in the average values presented in the Tables 1 and 2.
Quality assurance (QA) information
Field sampling, storage of fish samples as well as sample preparation for chemical analyses has been carried out according to the COMBINE programme. Analysing certified reference materials (CRMs) and participating in the external quality assessment schemes are useful tools to compare data with the other marine environmental monitoring laboratories. Certified reference materials BCR-718 (canned fresh herring, for analysed CBs) and CRM 598 (organochlorine pesticides in cod liver oil) were used. That QA-information is presented in the Table 3.
FIMR has participated in QUASIMEME Laboratory Performance Studies. In spring 2003 sample matrix in the QUASIMEME Study was herring. Those herring results indicated satisfactory performance on the basis of Z-values reported by QUASIMEME. Laboratory bias in relation to analysis of CRMs and QUASIMEME results are presented in the Figure 4.
Table 3. QA-information (for herrings collected in 2002) based on analysis of CRMs in 2003.
Figure 4. Comparison of bias values (QUASIMEME and CRMs).
1. Source: Finnish Institute of Marine Research, contact person Anna-Liisa Pikkarainen
2. Description of data: original unit of data on wet weight basis µg/kg (ww)
3. Geographical coverage: individual female herrings were collected from the Gulf of Bothnia and the Gulf of Finland (five sampling stations: Kalajoki, Pori, Ahvenanmaa, Hanko and Kotka areas).
4. Temporal coverage: once a year in autumn
Map of the sampling locations.
Last update 14 October 2003