Regional assessment of status and trends in PCB concentrations in biota

  • Overview
  • Summary of individual time series results
  • Regional assessment - methods
  • Regional assessment - availability of time series
  • Regional trends
  • Regional status compared to the Environmental Assessment Criterion (EAC)
  • Regional status compared to the Background Assessment Concentration (BAC)
  • PCB profiles

Overview

The 2022 OSPAR CEMP assessment describes the status and trends of contaminant concentrations in biota and sediment at monitoring stations in the OSPAR area. Assessments are made for a large number of time series, each of a single contaminant in a single species and tissue (for biota) at a single monitoring station. This document is one of a series that synthesises the results of the individual time series to assess status and trends at the MIME regional level. In particular, it considers PCB concentrations in biota, where the PCBs are CB28, CB52, CB101, CB118, CB138, CB153, CB180. For simplicity, the term ‘region’ is used throughout to describe MIME regions. OSPAR regions are always referred to as such.

The regional status assessments presented in this document are based on environmental thresholds. Regional status assessments based on human health tresholds can be found here.

The regional status assessments presented in this document are integrated with regional status assessments for other contaminants and biological effects using the CHASE approach. Details can be found here.

The following sections:

  • summarise the individual time series results
  • describe the methods used to combine the individual time series results to estimate regional status and trends
  • present the estimates of regional trends
  • present the estimates of regional status


Summary of individual time series results

A time series of PCB concentrations is assessed for status if:

  • there is at least one year with data in the period 2015 to 2020
  • there are at least three years of data over the whole time series
  • a parametric model can be fitted to the data and used to estimate the mean concentration in the final monitoring year (or, occasionally, if a non-parametric test of status is applied)

The conditions are more stringent for trends. Specifically, a time series is assessed for trends if:

  • there is at least one year with data in the period 2015 to 2020
  • there are at least five years of data over the whole time series
  • a parametric model can be fitted to the data and used to estimate the trend in mean concentration

Note that all trend assessments for individual time series and most status assessments are based on the fit of a parametric model. This is important because only the parametric results are passed into the regional assessments in the following sections. 164 of the 2310 PCB time series were assessed for status using a non-parametric test.

The first tab below shows all the monitoring stations where there are individual time series assessments of trend or status for PCBs. The purple circles are stations where there is a trend assessment for at least one PCB, and the light blue cirles are stations where there are only status assessments.

The next set of tabs show the trend and status assessments for each PCB in turn. The colours have the following meaning:

  • blue: the mean concentration is significantly (p < 0.05) below the Background Assessment Concentration (BAC)
  • green: the mean concentration is significantly (p < 0.05) below the Environmental Assessment Criterion (EAC)
  • red: the mean concentration is not signficantly below the EAC
  • black: there are no assessment criteria available

And the shapes have the following meaning:

  • downward triangle: the mean concentration is significantly decreasing (p < 0.05)
  • circle: there is no significant change in mean concentration (p > 0.05) or there are too few years to test for trends
  • upward triangle: the mean concentration is significantly increasing (p < 0.05)

The final set of tabs give:

  • the number of time series with upwards, downwards or no trend in each MIME and OSPAR region
  • the same information presented as proportions
  • the number of time series with blue, green or red status in each MIME and OSPAR region
  • the same information presented as proportions


Stations


CB28


CB52


CB101


CB118


CB138


CB153


CB180


Trend summary (numbers)

Number of time series with upwards, downwards or no trend by MIME and OSPAR region

OSPAR region MIME region status CB28 CB52 CB101 CB118 CB138 CB153 CB180 total
1 Barents Sea upward trend 0 0 0 0 0 1 0 1
no trend 1 2 2 6 5 5 2 23
downward trend 3 2 2 2 2 2 2 15
Greenland-Scotland ridge upward trend 0 0 1 1 1 1 0 4
no trend 0 2 2 1 3 4 3 15
downward trend 3 8 8 9 7 6 4 45
Norwegian Sea upward trend 0 0 0 0 0 0 0 0
no trend 2 2 3 3 3 3 2 18
downward trend 1 1 1 1 1 1 1 7
total upward trend 0 0 1 1 1 2 0 5
no trend 3 6 7 10 11 12 7 56
downward trend 7 11 11 12 10 9 7 67
2 Norwegian Trench upward trend 0 0 1 1 2 2 0 6
no trend 4 5 4 7 5 9 6 40
downward trend 2 3 11 9 9 5 4 43
Northern North Sea upward trend 0 0 0 3 0 1 1 5
no trend 2 3 13 14 18 22 10 82
downward trend 3 3 2 4 5 3 3 23
Skagerrak and Kattegat upward trend 0 0 0 1 0 2 1 4
no trend 9 10 13 12 16 18 8 86
downward trend 12 14 13 15 11 8 10 83
Southern North Sea upward trend 0 0 7 4 4 4 1 20
no trend 12 24 20 21 20 21 20 138
downward trend 6 1 6 8 9 8 9 47
Channel upward trend 0 0 0 0 0 1 2 3
no trend 8 16 19 20 16 24 24 127
downward trend 15 9 8 7 9 2 0 50
total upward trend 0 0 8 9 6 10 5 38
no trend 35 58 69 74 75 94 68 473
downward trend 38 30 40 43 43 26 26 246
3 Irish and Scottish West Coast upward trend 0 0 1 0 1 1 0 3
no trend 16 10 14 18 20 20 17 115
downward trend 7 8 10 7 4 5 5 46
Irish Sea upward trend 0 0 2 1 1 2 0 6
no trend 19 20 23 19 22 29 22 154
downward trend 11 11 13 19 13 8 11 86
Celtic Sea upward trend 0 0 1 0 1 1 0 3
no trend 17 16 16 15 18 20 19 121
downward trend 5 7 8 10 6 4 4 44
total upward trend 0 0 4 1 3 4 0 12
no trend 52 46 53 52 60 69 58 390
downward trend 23 26 31 36 23 17 20 176
4 Northern Bay of Biscay upward trend 0 1 0 0 0 0 0 1
no trend 13 22 26 25 27 26 26 165
downward trend 13 5 2 2 1 2 2 27
Iberian Sea upward trend 0 0 0 5 0 1 0 6
no trend 14 8 12 14 9 7 8 72
downward trend 5 10 14 7 17 18 14 85
Gulf of Cadiz upward trend 0 0 0 0 0 0 0 0
no trend 1 1 1 1 1 1 1 7
downward trend 0 0 0 0 0 0 0 0
total upward trend 0 1 0 5 0 1 0 7
no trend 28 31 39 40 37 34 35 244
downward trend 18 15 16 9 18 20 16 112


Trend summary (proportions)

Proportion of time series with upwards, downwards or no trend by MIME and OSPAR region

OSPAR region MIME region status CB28 CB52 CB101 CB118 CB138 CB153 CB180 total
1 Barents Sea upward trend 0 0 0 0 0 13 0 3
no trend 25 50 50 75 71 62 50 59
downward trend 75 50 50 25 29 25 50 38
Greenland-Scotland ridge upward trend 0 0 9 9 9 9 0 6
no trend 0 20 18 9 27 36 43 24
downward trend 100 80 73 82 64 55 57 70
Norwegian Sea upward trend 0 0 0 0 0 0 0 0
no trend 67 67 75 75 75 75 67 72
downward trend 33 33 25 25 25 25 33 28
total upward trend 0 0 5 4 5 9 0 4
no trend 30 35 37 44 50 52 50 44
downward trend 70 65 58 52 45 39 50 52
2 Norwegian Trench upward trend 0 0 6 6 13 13 0 7
no trend 67 62 25 41 31 56 60 45
downward trend 33 38 69 53 56 31 40 48
Northern North Sea upward trend 0 0 0 14 0 4 7 4
no trend 40 50 87 67 78 85 72 75
downward trend 60 50 13 19 22 11 21 21
Skagerrak and Kattegat upward trend 0 0 0 3 0 7 5 2
no trend 43 42 50 43 59 64 42 50
downward trend 57 58 50 54 41 29 53 48
Southern North Sea upward trend 0 0 21 12 12 12 3 10
no trend 67 96 61 64 61 64 67 67
downward trend 33 4 18 24 27 24 30 23
Channel upward trend 0 0 0 0 0 4 8 2
no trend 35 64 70 74 64 89 92 70
downward trend 65 36 30 26 36 7 0 28
total upward trend 0 0 7 7 5 8 5 5
no trend 48 66 59 59 60 72 69 62
downward trend 52 34 34 34 35 20 26 33
3 Irish and Scottish West Coast upward trend 0 0 4 0 4 4 0 2
no trend 70 56 56 72 80 77 77 70
downward trend 30 44 40 28 16 19 23 28
Irish Sea upward trend 0 0 5 2 3 5 0 2
no trend 63 65 61 49 61 74 67 63
downward trend 37 35 34 49 36 21 33 35
Celtic Sea upward trend 0 0 4 0 4 4 0 2
no trend 77 70 64 60 72 80 83 72
downward trend 23 30 32 40 24 16 17 26
total upward trend 0 0 5 1 3 4 0 2
no trend 69 64 60 58 70 77 74 68
downward trend 31 36 35 41 27 19 26 30
4 Northern Bay of Biscay upward trend 0 4 0 0 0 0 0 1
no trend 50 78 93 93 96 93 93 85
downward trend 50 18 7 7 4 7 7 14
Iberian Sea upward trend 0 0 0 19 0 4 0 4
no trend 74 44 46 54 35 27 36 44
downward trend 26 56 54 27 65 69 64 52
Gulf of Cadiz upward trend 0 0 0 0 0 0 0 0
no trend 100 100 100 100 100 100 100 100
downward trend 0 0 0 0 0 0 0 0
total upward trend 0 2 0 9 0 2 0 2
no trend 61 66 71 74 67 62 69 67
downward trend 39 32 29 17 33 36 31 31


Status summary (numbers)

Number of time series with each status by MIME and OSPAR region

OSPAR region MIME region status CB28 CB52 CB101 CB118 CB138 CB153 CB180 total
1 Barents Sea blue 0 0 0 3 0 0 0 3
green 9 9 11 2 11 11 9 62
red 0 0 0 6 0 0 0 6
Greenland-Scotland ridge blue 6 7 5 6 4 2 7 37
green 4 3 6 4 7 9 3 36
red 0 0 0 0 0 0 0 0
Norwegian Sea blue 0 0 0 0 0 0 0 0
green 4 4 4 1 5 5 4 27
red 0 0 1 5 1 1 1 9
total blue 6 7 5 9 4 2 7 40
green 17 16 21 7 23 25 16 125
red 0 0 1 11 1 1 1 15
2 Norwegian Trench blue 0 1 3 2 0 0 2 8
green 16 14 12 8 14 16 14 94
red 1 2 2 7 3 1 1 17
Northern North Sea blue 0 0 0 0 0 0 0 0
green 14 21 24 8 30 32 23 152
red 2 2 7 24 1 0 0 36
Skagerrak and Kattegat blue 11 5 0 1 0 0 9 26
green 19 22 27 15 27 29 19 158
red 0 2 3 14 3 1 1 24
Southern North Sea blue 3 0 0 0 0 0 2 5
green 26 32 25 1 27 35 33 179
red 9 5 12 36 8 1 1 72
Channel blue 21 3 0 0 0 0 4 28
green 7 22 21 6 22 28 25 131
red 1 4 8 23 7 2 0 45
total blue 35 9 3 3 0 0 17 67
green 82 111 109 38 120 140 114 714
red 13 15 32 104 22 5 3 194
3 Irish and Scottish West Coast blue 23 19 17 17 3 1 23 103
green 5 9 11 11 25 27 4 92
red 0 0 0 0 0 0 1 1
Irish Sea blue 8 6 0 0 0 0 5 19
green 26 29 33 15 39 41 37 220
red 6 7 9 27 3 1 0 53
Celtic Sea blue 23 15 6 5 1 0 17 67
green 7 17 24 14 30 31 14 137
red 1 0 2 13 1 1 0 18
total blue 54 40 23 22 4 1 45 189
green 38 55 68 40 94 99 55 449
red 7 7 11 40 4 2 1 72
4 Northern Bay of Biscay blue 32 11 0 0 0 0 1 44
green 1 22 32 6 31 33 32 157
red 0 0 1 27 2 0 0 30
Iberian Sea blue 12 14 3 0 0 0 12 41
green 14 12 21 6 23 26 14 116
red 0 0 2 20 3 0 0 25
Gulf of Cadiz blue 0 0 0 0 0 0 0 0
green 1 1 1 0 1 1 1 6
red 0 0 0 1 0 0 0 1
total blue 44 25 3 0 0 0 13 85
green 16 35 54 12 55 60 47 279
red 0 0 3 48 5 0 0 56


Status summary (proportions)

Proportion of time series with each status by MIME and OSPAR region

OSPAR region MIME region status CB28 CB52 CB101 CB118 CB138 CB153 CB180 total
1 Barents Sea blue 0 0 0 27 0 0 0 4
green 100 100 100 18 100 100 100 87
red 0 0 0 55 0 0 0 9
Greenland-Scotland ridge blue 60 70 45 60 36 18 70 51
green 40 30 55 40 64 82 30 49
red 0 0 0 0 0 0 0 0
Norwegian Sea blue 0 0 0 0 0 0 0 0
green 100 100 80 17 83 83 80 75
red 0 0 20 83 17 17 20 25
total blue 26 30 18 33 14 7 29 22
green 74 70 78 26 82 89 67 70
red 0 0 4 41 4 4 4 8
2 Norwegian Trench blue 0 6 18 12 0 0 12 7
green 94 82 70 47 82 94 82 79
red 6 12 12 41 18 6 6 14
Northern North Sea blue 0 0 0 0 0 0 0 0
green 88 91 77 25 97 100 100 81
red 12 9 23 75 3 0 0 19
Skagerrak and Kattegat blue 37 17 0 3 0 0 31 12
green 63 76 90 50 90 97 66 76
red 0 7 10 47 10 3 3 12
Southern North Sea blue 8 0 0 0 0 0 5 2
green 68 86 68 3 77 97 92 70
red 24 14 32 97 23 3 3 28
Channel blue 72 10 0 0 0 0 14 14
green 24 76 72 21 76 93 86 64
red 4 14 28 79 24 7 0 22
total blue 27 7 2 2 0 0 13 7
green 63 82 76 26 85 97 85 73
red 10 11 22 72 15 3 2 20
3 Irish and Scottish West Coast blue 82 68 61 61 11 4 82 53
green 18 32 39 39 89 96 14 47
red 0 0 0 0 0 0 4 0
Irish Sea blue 20 14 0 0 0 0 12 7
green 65 69 79 36 93 98 88 75
red 15 17 21 64 7 2 0 18
Celtic Sea blue 74 47 19 15 3 0 55 30
green 23 53 75 44 94 97 45 62
red 3 0 6 41 3 3 0 8
total blue 55 39 22 22 4 1 45 27
green 38 54 67 39 92 97 54 63
red 7 7 11 39 4 2 1 10
4 Northern Bay of Biscay blue 97 33 0 0 0 0 3 19
green 3 67 97 18 94 100 97 68
red 0 0 3 82 6 0 0 13
Iberian Sea blue 46 54 11 0 0 0 46 22
green 54 46 81 23 88 100 54 64
red 0 0 8 77 12 0 0 14
Gulf of Cadiz blue 0 0 0 0 0 0 0 0
green 100 100 100 0 100 100 100 86
red 0 0 0 100 0 0 0 14
total blue 73 42 5 0 0 0 22 20
green 27 58 90 20 92 100 78 67
red 0 0 5 80 8 0 0 13


Regional assessment - methods

Tabulating the number of time series with each status category by region provides a quick summary of the individual time series results. However, it does not provide an objective regional assessment of status. Similarly, tabulating the number of time series with an upward or downward trend does not provide an objective regional assessment of trend. This section describes how the individual time series results can by synthesised in a meta-analysis to assess both status and trend at the regional level. For PCBs, the meta-analysis is conducted in two parts: an analysis of the non-planar compounds CB28, CB52, CB101, CB138, CB153, CB180 and a separate analysis of the mono-ortho CB118. The results from the two parts are then combined.

Trends

For a regional trend assessment, the trend in each time series is summarised by the estimated change in log concentration over the last twenty years (or shorter if the time series doesn’t extend that far back). Regional trends for non-planar PCBs are then estimated by fitting the following linear mixed model by restricted maximum likelihood:

  • response: trend (yearly change in log concentration)
  • fixed model: region
  • random model: PCB + region.PCB + station + station.PCB + trend estimation variation + residual variation

The fixed model means that a trend is estimated for each region. Trends in the different non-planar PCBs are assumed to be broadly similar, because inputs and control measures are likely to affect all non-planar PCBs in a similar way. Each regional trend can thus be interpreted as the common trend in non-planar PCB concentrations in that region (i.e. the trend averaged across all non-planar PCBs).

The random model has six terms:

  • PCB allows for variation in trend between PCBs common to all regions
  • region.PCB allows for additional variation in trend between PCBs within regions
  • station allows for variation in trend between stations common to all PCBs
  • station.PCB allows for additional variation in trend between stations and PCBs common to all tissues and species within stations
  • trend estimation variation is the variance of the trend estimates from the individual time series analysis, assumed known and fixed
  • residual variation is the variation that cannot be explained by any of the fixed effects or the other random effects

The model for CB118 is simpler because there is only one compound to consider:

  • response: trend (yearly change in log concentration)
  • fixed model: region
  • random model: station + trend estimation variation + residual variation

The meta-analysis is restricted to time series from monitoring stations that are classified as ‘representative’ or ‘baseline’ (near pristine conditions or only subject to very diffuse inputs). ‘Impacted’ stations (those close to a point source) are omitted because trends there will likely reflect changes due to the point source and will be ‘unrepresentative’ at the regional level.

The meta-analysis is further restricted to:

  • regions with at least three trend stations with good geographic spread. Three stations is considered the minimum required to provide some sort of evidence base at the regional level
  • PCBs with trend information for at least three stations (over all regions): non-planar PCBs are treated as random effects in the meta-anlaysis, so information about trends in one PCB can be ‘borrowed’ from the trend information in the other PCBs

Status

For a regional status assessment, the status of each time series is summarised by the difference between the estimated mean log concentration in the final monitoring year and the log assessment concentration. This ensures that status is always measured on the same scale, even though the assessment concentration might vary between PCBs and species. Essentially the same linear mixed models as for trends are then fitted. For non-planar PCBs:

  • response: status (mean log concentration - log assessment concentration)
  • fixed model: region
  • random model: PCB + region.PCB + station + station.PCB + status estimation variation + residual variation

and for CB118:

  • response: status (mean log concentration - log assessment concentration)
  • fixed model: region
  • random model: station + status estimation variation + residual variation

where status estimation variation is the variation in the status estimates from the individual time series analysis, assumed known and fixed.

There are no restrictions on the time series used in the status meta-analysis based on the classification of the monitoring station; time series from baseline, representative and impacted stations are all included. However, the few time series with a non-parametric assessment of status must be excluded, because there is no summary measure of status to use in the mixed model.

Again, the meta-analysis is restricted to regions with at least three status stations with good geographic spread and to PCBs with status information for at least three stations (over all regions).

Presentation

The results of both the trend and status regional assessments are back-transformed for presentation. The estimated regional trend is then interpreted as the percentage yearly change in concentration and the estimated regional status as the ratio of the mean regional concentration to the assessment concentration. To illustrate the latter, a value of 1 indicates that the mean regional concentration is equal to the assessment concentration; a value of 0.5 indicates that it is half the assessment concentration, and a value of 2 indicates that it is twice the assessment concentration.


Regional assessment - availability of time series

This section provides more detail on the number and geographic spread of the time series available for the meta-analyses. The tabs show the stations with parametric trend and status assessments for each OSPAR region in turn, having excluded trend assessments at baseline and impacted stations. The purple circles are stations where there is a trend assessment for at least one PCB, and the light blue cirles are stations where there are only status assessments.

The following regions have an insufficient number or time series or spread of stations and are excluded from the regional assessment:

  • trend: Barents Sea, Gulf of Cadiz
  • status: Gulf of Cadiz


OSPAR region 1


OSPAR region 2


OSPAR region 3


OSPAR region 4


Regional trends

The first 4 tabs show:

  • Regional trends: estimates of the regional trend for non-planar PCBs and CB118 with pointwise 95% confidence intervals
  • Regional trends by PCB: regional trend estimates for each PCB with pointwise 95% confidence intervals plotted by PCB
  • Regional trends by region: regional trend estimates for each PCB with pointwise 95% confidence intervals plotted by region
  • Individual time series: the trend estimates from the individual time series on which the regional assessment is based. The estimates for regions with insufficient geographic spread (and excluded from the meta-analysis) are also shown.

The symbols in all these plots have the following interpretation:

  • downward triangle: the mean concentration is significantly decreasing (p < 0.05)
  • circle: there is no significant change in mean concentration (p > 0.05)
  • upward triangle: the mean concentration is significantly increasing (p < 0.05)

The final 2 tabs show the estimates of the regional trend for non-planar PCBs and CB118 and the regional trend by PCB.


Regional trends


Regional trends by PCB


Regional trends by region


Individual time series


Estimates by region

This table shows the estimates of the regional trend:

  • trend: the estimated mean yearly change in log concentration across the region (multiplied by 100 for presentation)
  • se: the corresponding standard error
  • lower, upper: the corresponding pointwise 95% confidence limits
  • % yearly change: the estimated mean % yearly change in concentration across the region
  • %yc lower, %yc upper: the corresponding pointwise 95% confidence limits


MIME region PCB trend se lower upper % yearly change %yc lower %yc upper
Greenland-Scotland ridge non-planar PCBs -6.10 1.78 -9.60 -2.61 -5.92 -9.15 -2.57
CB118 -4.71 1.36 -7.37 -2.04 -4.60 -7.10 -2.02
Norwegian Sea non-planar PCBs -3.50 3.44 -10.24 3.25 -3.44 -9.73 3.30
CB118 -9.88 4.67 -19.02 -0.73 -9.40 -17.32 -0.73
Norwegian Trench non-planar PCBs -1.71 1.88 -5.40 1.97 -1.70 -5.25 1.99
CB118 -1.82 1.47 -4.70 1.06 -1.80 -4.60 1.07
Northern North Sea non-planar PCBs -3.99 1.44 -6.82 -1.17 -3.91 -6.59 -1.16
CB118 -2.04 1.18 -4.35 0.28 -2.02 -4.26 0.28
Skagerrak and Kattegat non-planar PCBs -3.39 1.58 -6.49 -0.29 -3.34 -6.28 -0.29
CB118 -2.92 1.18 -5.24 -0.61 -2.88 -5.11 -0.61
Southern North Sea non-planar PCBs 1.16 1.32 -1.43 3.74 1.16 -1.42 3.81
CB118 -0.41 1.02 -2.41 1.59 -0.41 -2.38 1.60
Channel non-planar PCBs -4.05 1.33 -6.66 -1.43 -3.96 -6.44 -1.42
CB118 -4.03 1.00 -6.00 -2.07 -3.95 -5.82 -2.04
Irish and Scottish West Coast non-planar PCBs -6.32 1.41 -9.08 -3.55 -6.12 -8.68 -3.49
CB118 -6.07 1.21 -8.44 -3.71 -5.89 -8.10 -3.64
Irish Sea non-planar PCBs -3.34 1.23 -5.75 -0.94 -3.29 -5.58 -0.93
CB118 -4.31 0.83 -5.94 -2.69 -4.22 -5.77 -2.65
Celtic Sea non-planar PCBs -4.74 1.37 -7.43 -2.05 -4.63 -7.17 -2.03
CB118 -3.80 1.04 -5.83 -1.77 -3.73 -5.67 -1.75
Northern Bay of Biscay non-planar PCBs -3.88 1.37 -6.56 -1.20 -3.81 -6.35 -1.19
CB118 -4.06 1.42 -6.85 -1.28 -3.98 -6.62 -1.27
Iberian Sea non-planar PCBs -8.53 1.36 -11.20 -5.86 -8.18 -10.59 -5.69
CB118 -1.37 1.13 -3.58 0.84 -1.36 -3.51 0.84


Estimates by region and PCB

This table shows the estimates of the regional trend by determinand:

  • trend: the estimated mean yearly change in log concentration across the region (multiplied by 100 for presentation)
  • se: the corresponding standard error
  • lower, upper: the corresponding pointwise 95% confidence limits
  • % yearly change: the estimated mean % yearly change in concentration across the region
  • %yc lower, %yc upper: the corresponding pointwise 95% confidence limits


MIME region PCB trend se lower upper % yearly change %yc lower %yc upper
Greenland-Scotland ridge CB28 -8.73 1.79 -12.23 -5.22 -8.36 -11.51 -5.08
CB52 -6.94 1.66 -10.19 -3.68 -6.70 -9.69 -3.61
CB101 -5.78 1.64 -9.00 -2.56 -5.62 -8.60 -2.53
CB118 -4.71 1.36 -7.37 -2.04 -4.60 -7.10 -2.02
CB138 -5.57 1.62 -8.76 -2.39 -5.42 -8.38 -2.36
CB153 -4.41 1.63 -7.60 -1.22 -4.31 -7.31 -1.21
CB180 -5.20 1.72 -8.57 -1.82 -5.06 -8.22 -1.80
Norwegian Sea CB28 -5.69 3.59 -12.73 1.35 -5.53 -11.95 1.36
CB52 -4.59 3.60 -11.65 2.47 -4.48 -11.00 2.50
CB101 -3.43 3.54 -10.36 3.50 -3.38 -9.84 3.56
CB118 -9.88 4.67 -19.02 -0.73 -9.40 -17.32 -0.73
CB138 -2.74 3.54 -9.68 4.20 -2.70 -9.22 4.29
CB153 -1.58 3.54 -8.52 5.35 -1.57 -8.17 5.49
CB180 -2.95 3.63 -10.08 4.17 -2.91 -9.58 4.26
Norwegian Trench CB28 -3.75 1.94 -7.54 0.05 -3.68 -7.27 0.05
CB52 -3.86 1.93 -7.64 -0.09 -3.79 -7.35 -0.09
CB101 -2.53 1.74 -5.94 0.87 -2.50 -5.76 0.88
CB118 -1.82 1.47 -4.70 1.06 -1.80 -4.60 1.07
CB138 -0.75 1.73 -4.13 2.63 -0.75 -4.05 2.67
CB153 0.27 1.74 -3.13 3.67 0.27 -3.08 3.74
CB180 0.34 1.86 -3.30 3.99 0.34 -3.25 4.07
Northern North Sea CB28 -5.86 1.57 -8.93 -2.78 -5.69 -8.54 -2.75
CB52 -6.43 1.76 -9.88 -2.97 -6.23 -9.41 -2.93
CB101 -3.28 1.44 -6.10 -0.47 -3.23 -5.92 -0.46
CB118 -2.04 1.18 -4.35 0.28 -2.02 -4.26 0.28
CB138 -3.34 1.22 -5.74 -0.95 -3.29 -5.58 -0.95
CB153 -2.32 1.20 -4.68 0.04 -2.29 -4.57 0.04
CB180 -2.73 1.36 -5.39 -0.07 -2.70 -5.25 -0.07
Skagerrak and Kattegat CB28 -4.76 1.46 -7.62 -1.90 -4.64 -7.33 -1.88
CB52 -4.32 1.44 -7.13 -1.51 -4.23 -6.88 -1.49
CB101 -3.83 1.40 -6.58 -1.08 -3.76 -6.37 -1.07
CB118 -2.92 1.18 -5.24 -0.61 -2.88 -5.11 -0.61
CB138 -2.52 1.40 -5.25 0.22 -2.49 -5.12 0.22
CB153 -1.86 1.39 -4.59 0.87 -1.84 -4.48 0.87
CB180 -3.07 1.46 -5.93 -0.21 -3.02 -5.76 -0.21
Southern North Sea CB28 0.56 1.21 -1.82 2.93 0.56 -1.80 2.98
CB52 2.68 1.19 0.35 5.00 2.71 0.35 5.13
CB101 1.34 1.11 -0.85 3.52 1.34 -0.84 3.58
CB118 -0.41 1.02 -2.41 1.59 -0.41 -2.38 1.60
CB138 0.69 1.11 -1.49 2.87 0.69 -1.48 2.91
CB153 2.01 1.09 -0.13 4.16 2.03 -0.13 4.24
CB180 -0.34 1.13 -2.56 1.88 -0.34 -2.53 1.90
Channel CB28 -8.21 1.19 -10.55 -5.87 -7.88 -10.01 -5.70
CB52 -5.84 1.26 -8.31 -3.37 -5.67 -7.97 -3.31
CB101 -4.24 1.14 -6.48 -1.99 -4.15 -6.27 -1.97
CB118 -4.03 1.00 -6.00 -2.07 -3.95 -5.82 -2.04
CB138 -4.10 1.16 -6.37 -1.83 -4.02 -6.17 -1.81
CB153 -1.50 1.14 -3.73 0.73 -1.49 -3.66 0.74
CB180 -0.39 1.19 -2.73 1.95 -0.39 -2.69 1.97
Irish and Scottish West Coast CB28 -8.77 1.49 -11.69 -5.85 -8.40 -11.03 -5.68
CB52 -10.07 1.45 -12.91 -7.23 -9.58 -12.11 -6.97
CB101 -7.52 1.28 -10.03 -5.01 -7.24 -9.54 -4.88
CB118 -6.07 1.21 -8.44 -3.71 -5.89 -8.10 -3.64
CB138 -3.52 1.22 -5.91 -1.12 -3.46 -5.74 -1.12
CB153 -2.92 1.20 -5.26 -0.57 -2.87 -5.12 -0.57
CB180 -5.12 1.44 -7.95 -2.28 -4.99 -7.64 -2.26
Irish Sea CB28 -4.21 1.11 -6.38 -2.03 -4.12 -6.18 -2.01
CB52 -4.78 1.07 -6.87 -2.68 -4.66 -6.64 -2.65
CB101 -2.95 0.96 -4.84 -1.06 -2.91 -4.72 -1.06
CB118 -4.31 0.83 -5.94 -2.69 -4.22 -5.77 -2.65
CB138 -2.48 0.96 -4.36 -0.61 -2.45 -4.26 -0.61
CB153 -1.76 0.95 -3.62 0.10 -1.75 -3.55 0.10
CB180 -3.87 1.02 -5.87 -1.88 -3.80 -5.70 -1.87
Celtic Sea CB28 -7.54 1.28 -10.06 -5.02 -7.27 -9.57 -4.90
CB52 -7.48 1.35 -10.12 -4.84 -7.20 -9.62 -4.72
CB101 -4.10 1.22 -6.48 -1.71 -4.01 -6.27 -1.70
CB118 -3.80 1.04 -5.83 -1.77 -3.73 -5.67 -1.75
CB138 -3.23 1.19 -5.56 -0.89 -3.18 -5.41 -0.89
CB153 -2.10 1.16 -4.37 0.16 -2.08 -4.28 0.16
CB180 -4.00 1.27 -6.50 -1.50 -3.92 -6.29 -1.49
Northern Bay of Biscay CB28 -6.61 1.24 -9.03 -4.18 -6.39 -8.63 -4.09
CB52 -3.65 1.21 -6.02 -1.28 -3.58 -5.84 -1.27
CB101 -3.89 1.34 -6.52 -1.27 -3.82 -6.31 -1.26
CB118 -4.06 1.42 -6.85 -1.28 -3.98 -6.62 -1.27
CB138 -5.01 1.42 -7.80 -2.23 -4.89 -7.51 -2.20
CB153 -2.44 1.25 -4.88 0.01 -2.41 -4.77 0.01
CB180 -1.68 1.33 -4.29 0.93 -1.66 -4.20 0.93
Iberian Sea CB28 -8.65 1.33 -11.26 -6.05 -8.29 -10.65 -5.87
CB52 -11.26 1.25 -13.71 -8.80 -10.65 -12.81 -8.43
CB101 -7.67 1.16 -9.94 -5.40 -7.38 -9.47 -5.25
CB118 -1.37 1.13 -3.58 0.84 -1.36 -3.51 0.84
CB138 -7.03 1.13 -9.24 -4.83 -6.79 -8.83 -4.71
CB153 -6.43 1.13 -8.64 -4.22 -6.23 -8.28 -4.14
CB180 -10.13 1.22 -12.52 -7.74 -9.64 -11.77 -7.45


Regional status compared to the Environmental Assessment Criterion (EAC)

The first 4 tabs show:

  • Regional status: estimates of the regional status for non-planar PCBs and CB118 with pointwise upper one-sided 95% confidence intervals
  • Regional status by PCB: regional status estimates for each PCB with pointwise upper one-sided 95% confidence intervals plotted by PCB
  • Regional status by region: regional status estimates for each PCB with pointwise upper one-sided 95% confidence intervals plotted by region
  • Individual time series: the status estimates from the individual time series on which the regional assessment is based. The estimates for regions with insufficient geographic spread (and excluded from the meta-analysis) are also shown.

The symbols in all the plots have the following interpretation:

  • blue: the mean concentration is significantly (p < 0.05) below the Background Assessment Concentration (BAC)
  • green: the mean concentration is significantly (p < 0.05) below the EAC
  • red: the mean concentration is not significantly below the EAC

Note that to see why some points might be coloured blue, it is necessary to look ahead to the next section, where status is compared to the BAC. Unfortunately, it isn’t easy to present the assessment of status relative to the EAC with the assessment of status relative to the BAC because the ratio of the BAC to the EAC can vary between PCBs and species.

The final 2 tabs shows the estimates of the regional status for non-planar PCBs and CB118 and the regional status by PCB.


Regional status


Regional status by PCB


Regional status by region


Individual time series


Estimates by region

This table shows the estimates of the regional status:

  • status: the estimated mean log concentration minus the log EAC
  • se: the corresponding standard error
  • upper: the corresponding pointwise upper one-sided 95% confidence limit
  • concentration: the estimated mean concentration relative to the EAC
  • conc upper: the corresponding pointwise upper one-sided 95% confidence limit


MIME region PCB status se upper concentration conc upper
Barents Sea non-planar PCBs -3.23 0.45 -2.50 0.04 0.08
CB118 -0.65 0.27 -0.20 0.52 0.82
Greenland-Scotland ridge non-planar PCBs -4.40 0.45 -3.67 0.01 0.03
CB118 -1.77 0.28 -1.30 0.17 0.27
Norwegian Sea non-planar PCBs -2.45 0.52 -1.61 0.09 0.20
CB118 0.32 0.38 0.93 1.37 2.54
Norwegian Trench non-planar PCBs -3.10 0.41 -2.42 0.05 0.09
CB118 -0.41 0.22 -0.05 0.66 0.96
Northern North Sea non-planar PCBs -2.75 0.39 -2.11 0.06 0.12
CB118 -0.05 0.17 0.24 0.95 1.26
Skagerrak and Kattegat non-planar PCBs -2.71 0.39 -2.07 0.07 0.13
CB118 -0.03 0.17 0.25 0.97 1.28
Southern North Sea non-planar PCBs -2.17 0.38 -1.55 0.11 0.21
CB118 0.60 0.16 0.87 1.82 2.39
Channel non-planar PCBs -2.42 0.39 -1.78 0.09 0.17
CB118 0.59 0.17 0.87 1.80 2.39
Irish and Scottish West Coast non-planar PCBs -4.66 0.39 -4.01 0.01 0.02
CB118 -2.09 0.18 -1.79 0.12 0.17
Irish Sea non-planar PCBs -2.45 0.38 -1.83 0.09 0.16
CB118 0.03 0.14 0.27 1.03 1.31
Celtic Sea non-planar PCBs -3.52 0.39 -2.88 0.03 0.06
CB118 -0.78 0.17 -0.51 0.46 0.60
Northern Bay of Biscay non-planar PCBs -2.91 0.38 -2.28 0.05 0.10
CB118 -0.32 0.17 -0.04 0.72 0.96
Iberian Sea non-planar PCBs -3.02 0.39 -2.38 0.05 0.09
CB118 0.07 0.18 0.37 1.07 1.45


Estimates by region and PCB

This table shows the estimates of the regional trend by determinand:

  • status: the estimated mean log concentration minus the log EAC
  • se: the corresponding standard error
  • upper: the corresponding pointwise upper one-sided 95% confidence limit
  • concentration: the estimated mean concentration relative to the EAC
  • conc upper: the corresponding pointwise upper one-sided 95% confidence limit


MIME region PCB status se upper concentration conc upper
Barents Sea CB28 -3.79 0.34 -3.24 0.02 0.04
CB52 -3.20 0.34 -2.65 0.04 0.07
CB101 -2.18 0.32 -1.66 0.11 0.19
CB118 -0.65 0.27 -0.20 0.52 0.82
CB138 -2.47 0.30 -1.97 0.08 0.14
CB153 -3.72 0.30 -3.22 0.02 0.04
CB180 -4.04 0.34 -3.48 0.02 0.03
Greenland-Scotland ridge CB28 -4.45 0.36 -3.86 0.01 0.02
CB52 -4.13 0.31 -3.62 0.02 0.03
CB101 -3.50 0.30 -3.00 0.03 0.05
CB118 -1.77 0.28 -1.30 0.17 0.27
CB138 -3.80 0.30 -3.30 0.02 0.04
CB153 -4.94 0.30 -4.45 0.01 0.01
CB180 -5.58 0.33 -5.03 0.00 0.01
Norwegian Sea CB28 -3.22 0.44 -2.49 0.04 0.08
CB52 -2.70 0.43 -1.98 0.07 0.14
CB101 -1.35 0.42 -0.66 0.26 0.52
CB118 0.32 0.38 0.93 1.37 2.54
CB138 -1.51 0.41 -0.83 0.22 0.43
CB153 -2.71 0.41 -2.04 0.07 0.13
CB180 -3.23 0.44 -2.52 0.04 0.08
Norwegian Trench CB28 -3.69 0.29 -3.22 0.02 0.04
CB52 -3.15 0.27 -2.70 0.04 0.07
CB101 -2.14 0.25 -1.73 0.12 0.18
CB118 -0.41 0.22 -0.05 0.66 0.96
CB138 -2.28 0.25 -1.88 0.10 0.15
CB153 -3.50 0.25 -3.09 0.03 0.05
CB180 -3.82 0.26 -3.39 0.02 0.03
Northern North Sea CB28 -3.23 0.22 -2.87 0.04 0.06
CB52 -3.19 0.21 -2.84 0.04 0.06
CB101 -1.92 0.20 -1.60 0.15 0.20
CB118 -0.05 0.17 0.24 0.95 1.26
CB138 -1.89 0.19 -1.58 0.15 0.21
CB153 -3.10 0.18 -2.80 0.05 0.06
CB180 -3.16 0.21 -2.82 0.04 0.06
Skagerrak and Kattegat CB28 -2.98 0.20 -2.65 0.05 0.07
CB52 -2.60 0.20 -2.28 0.07 0.10
CB101 -1.79 0.19 -1.48 0.17 0.23
CB118 -0.03 0.17 0.25 0.97 1.28
CB138 -1.89 0.19 -1.57 0.15 0.21
CB153 -3.11 0.19 -2.80 0.04 0.06
CB180 -3.88 0.20 -3.55 0.02 0.03
Southern North Sea CB28 -2.76 0.19 -2.46 0.06 0.09
CB52 -2.17 0.18 -1.88 0.11 0.15
CB101 -1.11 0.17 -0.82 0.33 0.44
CB118 0.60 0.16 0.87 1.82 2.39
CB138 -1.29 0.17 -1.01 0.27 0.36
CB153 -2.34 0.17 -2.06 0.10 0.13
CB180 -3.36 0.18 -3.08 0.03 0.05
Channel CB28 -3.53 0.19 -3.21 0.03 0.04
CB52 -2.44 0.20 -2.12 0.09 0.12
CB101 -1.19 0.19 -0.88 0.30 0.42
CB118 0.59 0.17 0.87 1.80 2.39
CB138 -1.34 0.19 -1.02 0.26 0.36
CB153 -2.32 0.19 -2.01 0.10 0.13
CB180 -3.68 0.19 -3.36 0.03 0.03
Irish and Scottish West Coast CB28 -4.57 0.21 -4.22 0.01 0.01
CB52 -4.63 0.21 -4.28 0.01 0.01
CB101 -3.76 0.20 -3.43 0.02 0.03
CB118 -2.09 0.18 -1.79 0.12 0.17
CB138 -3.87 0.20 -3.54 0.02 0.03
CB153 -4.92 0.20 -4.60 0.01 0.01
CB180 -6.18 0.21 -5.83 0.00 0.00
Irish Sea CB28 -2.49 0.17 -2.21 0.08 0.11
CB52 -2.38 0.17 -2.10 0.09 0.12
CB101 -1.55 0.16 -1.28 0.21 0.28
CB118 0.03 0.14 0.27 1.03 1.31
CB138 -1.86 0.16 -1.60 0.16 0.20
CB153 -2.98 0.16 -2.71 0.05 0.07
CB180 -3.43 0.17 -3.16 0.03 0.04
Celtic Sea CB28 -3.95 0.20 -3.63 0.02 0.03
CB52 -3.51 0.19 -3.19 0.03 0.04
CB101 -2.41 0.19 -2.10 0.09 0.12
CB118 -0.78 0.17 -0.51 0.46 0.60
CB138 -2.72 0.19 -2.40 0.07 0.09
CB153 -3.66 0.19 -3.36 0.03 0.03
CB180 -4.84 0.19 -4.53 0.01 0.01
Northern Bay of Biscay CB28 -4.02 0.18 -3.72 0.02 0.02
CB52 -2.94 0.18 -2.65 0.05 0.07
CB101 -1.75 0.19 -1.44 0.17 0.24
CB118 -0.32 0.17 -0.04 0.72 0.96
CB138 -2.13 0.19 -1.82 0.12 0.16
CB153 -2.65 0.18 -2.35 0.07 0.10
CB180 -3.97 0.18 -3.67 0.02 0.03
Iberian Sea CB28 -3.44 0.22 -3.08 0.03 0.05
CB52 -3.70 0.22 -3.35 0.02 0.04
CB101 -1.95 0.20 -1.62 0.14 0.20
CB118 0.07 0.18 0.37 1.07 1.45
CB138 -1.84 0.20 -1.52 0.16 0.22
CB153 -2.92 0.20 -2.59 0.05 0.07
CB180 -4.25 0.21 -3.90 0.01 0.02


Regional status compared to the Background Assessment Concentration (BAC)

The first 4 tabs show:

  • Regional status: estimates of the regional status for non-planar PCBs and CB118 with pointwise upper one-sided 95% confidence intervals
  • Regional status by PCB: regional status estimates for each PCB with pointwise upper one-sided 95% confidence intervals plotted by PCB
  • Regional status by region: regional status estimates for each PCB with pointwise upper one-sided 95% confidence intervals plotted by region
  • Individual time series: the status estimates from the individual time series on which the regional assessment is based. The estimates for regions with insufficient geographic spread (and excluded from the meta-analysis) are also shown.

The symbols in all the plots have the following interpretation:

  • blue: the mean concentration is significantly (p < 0.05) below the BAC
  • green: the mean concentration is significantly (p < 0.05) below the Environmental Assessment Criterion (EAC)
  • red: the mean concentration is not significantly below the EAC

The final 2 tabs shows the estimates of the regional status for non-planar PCBs and CB118 and the regional status by PCB.


Regional status


Regional status by PCB


Regional status by region


Individual time series


Estimates by region

This table shows the estimates of the regional status:

  • status: the estimated mean log concentration minus the log BAC
  • se: the corresponding standard error
  • upper: the corresponding pointwise upper one-sided 95% confidence limit
  • concentration: the estimated mean concentration relative to the BAC
  • conc upper: the corresponding pointwise upper one-sided 95% confidence limit


MIME region PCB status se upper concentration conc upper
Barents Sea non-planar PCBs 1.86 0.75 3.09 6.42 21.93
CB118 2.14 0.48 2.93 8.51 18.64
Greenland-Scotland ridge non-planar PCBs -0.01 0.75 1.21 0.99 3.36
CB118 0.49 0.50 1.31 1.64 3.71
Norwegian Sea non-planar PCBs 2.79 0.87 4.22 16.24 68.08
CB118 3.27 0.65 4.34 26.41 76.62
Norwegian Trench non-planar PCBs 1.32 0.69 2.45 3.76 11.61
CB118 1.81 0.38 2.44 6.10 11.48
Northern North Sea non-planar PCBs 1.67 0.63 2.71 5.31 15.01
CB118 2.25 0.30 2.74 9.47 15.49
Skagerrak and Kattegat non-planar PCBs 1.68 0.64 2.74 5.36 15.44
CB118 2.14 0.31 2.65 8.54 14.13
Southern North Sea non-planar PCBs 2.64 0.62 3.67 14.07 39.32
CB118 3.35 0.29 3.82 28.53 45.60
Channel non-planar PCBs 1.41 0.64 2.45 4.08 11.59
CB118 2.21 0.30 2.70 9.11 14.87
Irish and Scottish West Coast non-planar PCBs -1.03 0.64 0.02 0.36 1.02
CB118 -0.64 0.31 -0.13 0.53 0.88
Irish Sea non-planar PCBs 1.97 0.62 2.98 7.16 19.78
CB118 2.27 0.25 2.68 9.63 14.58
Celtic Sea non-planar PCBs 0.18 0.63 1.23 1.20 3.42
CB118 0.72 0.29 1.19 2.05 3.29
Northern Bay of Biscay non-planar PCBs 0.70 0.63 1.73 2.01 5.64
CB118 1.10 0.29 1.57 3.00 4.80
Iberian Sea non-planar PCBs 0.67 0.64 1.73 1.95 5.63
CB118 1.57 0.31 2.08 4.79 8.03


Estimates by region and PCB

This table shows the estimates of the regional trend by determinand:

  • status: the estimated mean log concentration minus the log BAC
  • se: the corresponding standard error
  • upper: the corresponding pointwise upper one-sided 95% confidence limit
  • concentration: the estimated mean concentration relative to the BAC
  • conc upper: the corresponding pointwise upper one-sided 95% confidence limit


MIME region PCB status se upper concentration conc upper
Barents Sea CB28 -0.06 0.53 0.81 0.94 2.24
CB52 1.18 0.53 2.05 3.24 7.74
CB101 2.26 0.52 3.11 9.57 22.38
CB118 2.14 0.48 2.93 8.51 18.64
CB138 2.94 0.51 3.77 18.87 43.47
CB153 3.25 0.51 4.09 25.91 59.68
CB180 1.59 0.53 2.47 4.91 11.79
Greenland-Scotland ridge CB28 -1.45 0.54 -0.56 0.23 0.57
CB52 -0.61 0.51 0.24 0.55 1.27
CB101 0.21 0.51 1.04 1.23 2.84
CB118 0.49 0.50 1.31 1.64 3.71
CB138 0.95 0.51 1.78 2.59 5.95
CB153 1.39 0.51 2.22 4.01 9.22
CB180 -0.56 0.53 0.30 0.57 1.35
Norwegian Sea CB28 0.65 0.71 1.82 1.92 6.17
CB52 1.77 0.70 2.92 5.85 18.53
CB101 3.22 0.69 4.36 24.97 78.03
CB118 3.27 0.65 4.34 26.41 76.62
CB138 4.06 0.69 5.19 58.14 179.57
CB153 4.43 0.69 5.56 83.82 258.99
CB180 2.59 0.70 3.75 13.38 42.48
Norwegian Trench CB28 -0.66 0.44 0.06 0.52 1.07
CB52 0.45 0.43 1.15 1.57 3.17
CB101 1.59 0.41 2.26 4.89 9.59
CB118 1.81 0.38 2.44 6.10 11.48
CB138 2.49 0.41 3.16 12.07 23.67
CB153 2.86 0.41 3.53 17.40 34.12
CB180 1.22 0.42 1.91 3.39 6.77
Northern North Sea CB28 -0.15 0.33 0.39 0.86 1.48
CB52 0.42 0.32 0.95 1.52 2.60
CB101 1.85 0.31 2.37 6.37 10.66
CB118 2.25 0.30 2.74 9.47 15.49
CB138 2.85 0.31 3.36 17.37 28.83
CB153 3.21 0.31 3.71 24.76 40.89
CB180 1.83 0.32 2.36 6.23 10.55
Skagerrak and Kattegat CB28 -0.00 0.34 0.55 1.00 1.73
CB52 0.99 0.33 1.54 2.68 4.65
CB101 2.01 0.33 2.56 7.46 12.87
CB118 2.14 0.31 2.65 8.54 14.13
CB138 2.84 0.33 3.38 17.04 29.36
CB153 3.17 0.33 3.72 23.86 41.06
CB180 1.07 0.34 1.62 2.91 5.07
Southern North Sea CB28 0.71 0.30 1.21 2.04 3.36
CB52 1.84 0.30 2.33 6.32 10.31
CB101 3.06 0.29 3.54 21.27 34.50
CB118 3.35 0.29 3.82 28.53 45.60
CB138 3.87 0.29 4.35 48.05 77.67
CB153 4.37 0.29 4.85 78.92 127.48
CB180 2.01 0.30 2.50 7.46 12.13
Channel CB28 -1.11 0.32 -0.59 0.33 0.55
CB52 0.47 0.32 0.99 1.60 2.70
CB101 1.91 0.32 2.43 6.76 11.35
CB118 2.21 0.30 2.70 9.11 14.87
CB138 2.85 0.32 3.37 17.28 29.05
CB153 3.46 0.31 3.98 31.78 53.26
CB180 0.86 0.32 1.38 2.36 3.98
Irish and Scottish West Coast CB28 -2.35 0.34 -1.79 0.10 0.17
CB52 -1.91 0.34 -1.35 0.15 0.26
CB101 -0.86 0.33 -0.31 0.42 0.73
CB118 -0.64 0.31 -0.13 0.53 0.88
CB138 0.12 0.33 0.66 1.12 1.94
CB153 0.66 0.33 1.20 1.93 3.32
CB180 -1.86 0.34 -1.30 0.16 0.27
Irish Sea CB28 0.54 0.28 1.00 1.72 2.72
CB52 1.23 0.28 1.68 3.41 5.38
CB101 2.20 0.27 2.65 9.04 14.18
CB118 2.27 0.25 2.68 9.63 14.58
CB138 2.89 0.27 3.34 17.99 28.17
CB153 3.34 0.27 3.79 28.31 44.34
CB180 1.61 0.28 2.06 4.98 7.84
Celtic Sea CB28 -1.65 0.32 -1.13 0.19 0.32
CB52 -0.71 0.32 -0.19 0.49 0.82
CB101 0.55 0.31 1.07 1.74 2.92
CB118 0.72 0.29 1.19 2.05 3.29
CB138 1.34 0.31 1.86 3.83 6.42
CB153 2.00 0.31 2.51 7.35 12.30
CB180 -0.42 0.32 0.10 0.66 1.10
Northern Bay of Biscay CB28 -1.82 0.30 -1.32 0.16 0.27
CB52 -0.26 0.30 0.23 0.77 1.26
CB101 1.12 0.30 1.61 3.05 5.02
CB118 1.10 0.29 1.57 3.00 4.80
CB138 1.84 0.30 2.34 6.31 10.40
CB153 2.92 0.30 3.42 18.56 30.42
CB180 0.39 0.30 0.88 1.47 2.41
Iberian Sea CB28 -1.17 0.34 -0.60 0.31 0.55
CB52 -0.94 0.34 -0.38 0.39 0.69
CB101 1.01 0.33 1.55 2.74 4.73
CB118 1.57 0.31 2.08 4.79 8.03
CB138 2.22 0.33 2.76 9.18 15.82
CB153 2.74 0.33 3.28 15.48 26.68
CB180 0.16 0.34 0.72 1.17 2.04


PCB profiles

The profile of concentrations across PCBs can sometimes be useful for examining sources, and for comparing concentrations across regions where assessment criteria are not available. Profiles were examined by fitting the following linear mixed model to the non-planar PCBs by restricted maximum likelihood:

  • response: mean log concentration
  • fixed model: region
  • random model: PCB + region.PCB + station + station.PCB + estimation variance + residual variation

where, for each time series, the mean log concentration is the estimated mean log concentration in the final monitoring year and the estimation variance is the variance associated with this estimate. The usual simplified model was also fitted to CB118 and the results combined.

The estimated PCB concentration profiles by region are shown below with pointwise 95% confidence limits. The units are ug/kg lw.