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Lead concentrations in fish liver
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Figure 1. Spatial variation in geometric mean concentration (ng/g dry w.) of lead in herring liver (2000-2004). The highest concentrations around 164 ng/g were found in the southern Bothnian Sea and southern Baltic Proper, the lowest concentrations around 75 ng/g in the Skagerakk and in the northern Bothnian Bay. Data obtained from ICES database and originates from both the Finnish and Swedish national monitoring programmes analysed at different laboratories.
Key message
Lead is showing significant declining trends in almost all investigated biotic matrices of sufficient length, obviously as a result of measures taken to reduce discharges of lead to the environment.
Results and assessments
Relevance of the indicator for describing developments in the environment
Lead concentration in liver tissue from various species show coherent trends of similar magnitudes from various regions. The investigated species are commonly used for human consumption.
Policy relevance and policy references
Lead is one of the mandatory contaminants that should be analysed and reported within both the OSPARCOM and HELCOM conventions. The North Sea Conference (1984, 1987, 1990) that covers all routes of pollution to the North Sea, states that the lead discharges are to be reduced by 70% between 1985 and 1995, using 1985 as a base year. The Minister Declaration from 1988, within HELCOM, calls for a reduction of the discharges of lead to air and water by 50% by 1995 with 1987 as a base year.
Assessment
At Harufjärden (-3.5%) Ängskärsklubb (autumn, -4.4%) and Landsort (-4.7%) the investigated timeseries in herring liver show significant decreasing trends.
Lead concentrations in cod liver (after adjusting for varying fat content) showed decreasing trends from SE Gotland (-6.3%) and Fladen (about –4.3%).
At the coastal sites Holmöarna (Bothnian Sea) and Kvädöfjärden (Baltic Proper) perch liver is sampled. Lead concentrations showed decreasing trends: -10% at both sites.
Figure 2. Temporal trends of lead concentration (ug/g dry w.) in herring liver (1983-2005).
Figure 3. Temporal trends of lead concentration (ug/g dry w.) in cod liver (1983-2005).
References
Bignert, A., Nyberg E., Asplund L., Willander A. 2006. Comments Concerning the National Swedish Contaminant Monitoring Programme in Marine Biota. Report to the Swedish Environmental Protection Agency, 2006. 115 pp.
Grimås, U., Göthberg, A., Notter, M., Olsson, M., and Reutergårdh, L. 1985. Fat Amount - A Factor to Consider in Monitoring Studies of Heavy Metals in Cod Liver. Ambio VOL 14, No 3, pp 175 - 178
Data
Estimated geometric concentrations of lead (ug/g dry weight) for the last sampled year in various matrices and sites during the investigated time period. The age intervals for fish are also presented together with the total number of analyses and the number of years of the various time-series.
| Matrix | age | n | n yrs | year | trend (95% ci) | last year (95% ci) |
| Herring liver | ||||||
| Harufj. autumn | 3-4 | 368 | 23 | 81-05 | -3.5(-6.2, -.89)* | .077 (.054-.112) |
| Ängskärskl. aut. | 3-5 | 407 | 24 | 81-05 | -4.4 (-6.2, -2.6)* | .088 (.068-.112) |
| Landsort | 3-5 | 392 | 25 | 81-05 | -4.7 (-6.4,-2.9)* | .102 (.080-.130) |
| Utlängan, aut. | 2-4 | 390 | 25 | 81-05 | -2.2 (-3.8, -.56)* | .150 (.119-.188) |
| Fladen | 2-3 | 467 | 25 | 81-05 | -4.5 (-6.5,-2.4)* | .070 (.035-.082) |
| Cod liver | ||||||
| SE Gotland | 3-4 | 359 | 25 | 81-05 | -6.3 (-8.7,-3.9)* | .021 (.015-.030) |
| Fladen | 2-4 | 445 | 24 | 81-05 | -4.3 (-6.7,-1.9)* | .041 (.030-.058) |
| Perch liver | ||||||
| Holmöarna | 3-7 | 100 | 10 | 95-04 | -10(-20,-.21)* | .027 (.016-.047) |
| Kvädöfjärden | 3-7 | 90 | 9 | 95-04 | -10(-16,-4.9)* | .029 (.022-.040) |
* significant trend, p < 0.05
Metadata
1. Technical information
Data source: The National Swedish Monitoring Program of Contaminants in Biota
Sampling, sample preparation, storage in specimen bank and evaluation of results are carried out by the Department of Contaminant Research at the Swedish Museum of Natural History, Stockholm. Chemical Analysis is carried out at the Centre for Environmental Monitoring at the University of Agriculture, Uppsala.
Geographical coverage: see data table and map.
Temporal coverage: see data table and figures.
Methodology and frequency of data collection, see Bignert et al, 2006
Methodology of data manipulation. For a detailed description of statistical methods use, see Bignert et al. 2006. Lead concentration are adjusted for varying fat content by ANCOVA. For a comprehensive description of the relationship between heavy metal concentration and fat content in cod liver, see Grimås et al. 1985.
2. Quality information
The number of years required to detect an annual change of 5% varied between 15 to 24 years for the herring time-series with a power to detect a 5% annual change is close to 1. An annual change greater than 10% would likely be detected.
The number of years required to detect an annual change of 5% is approximately 20 years for the cod time-series with a power to detect a 5% annual change is close to 1. An annual change greater than 15% would likely be detected.
For reference purposes, please cite this indicator fact sheet as follows:
[Author’s name(s)], [Year]. [Indicator Fact Sheet title]. HELCOM Indicator Fact Sheets 2006. Online. [Date Viewed], http://www.helcom.fi/environment2/ifs/en_GB/cover/.
Last updated: 25.9.2006