MIME regional assessment of status and trends in PAH concentrations in sediment

Overview

The 2017 MIME assessment describes the trends and status 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 (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 PAH concentrations in sediment, where the PAHs are PA, ANT, FLU, PYR, BAA, CHR, BAP, BGHIP, ICDP. For simplicity, the term ‘region’ is used throughout to describe MIME regions. OSPAR regions are always referred to as such.

The following sections:

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


Summary of individual time series results

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

  • there is at least one year with data in the period 2010 to 2015
  • 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 2010 to 2015
  • 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 concentrations

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. Only 9 of 1597 PAH 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 PAHs. The magenta circles are stations where there is a trend assessment for at least one PAH, and the cyan cirles are stations where there are only status assessments.

The next set of tabs show the trend and status assessments for each PAH 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 Effects Range Low (ERL)
  • red: the mean concentration is not signficantly below the Effects Range Low (ERL)

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)
  • 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

Note that there are no ERLs for BGHIP and ICDP. Time series for these PAHs are only assessed against the BAC, and are coloured blue if significantly below the BAC and orange otherwise.


Stations


PA


ANT


FLU


PYR


BAA


CHR


BAP


BGHIP


ICDP


Trend summary (numbers)

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

OSPAR region MIME region status PA ANT FLU PYR BAA CHR BAP BGHIP ICDP total
2 Northern North Sea upward trend 1 1 2 1 2 1 2 2 2 14
no trend 23 17 20 21 17 18 17 17 19 169
downward trend 1 2 3 3 3 2 3 3 1 21
Southern North Sea upward trend 1 2 2 1 0 1 0 0 0 7
no trend 27 27 29 29 31 29 29 24 28 253
downward trend 11 8 7 9 7 9 10 15 11 87
Channel upward trend 0 0 0 0 0 0 0 0 0 0
no trend 5 5 5 5 5 2 5 4 5 41
downward trend 1 0 1 1 1 1 1 2 1 9
total upward trend 2 3 4 2 2 2 2 2 2 21
no trend 55 49 54 55 53 49 51 45 52 463
downward trend 13 10 11 13 11 12 14 20 13 117
3 Irish and Scottish West Coast upward trend 0 0 0 1 1 0 1 0 0 3
no trend 9 6 9 8 8 6 7 9 9 71
downward trend 1 1 1 1 0 1 1 1 1 8
Irish Sea upward trend 1 0 1 1 0 2 0 0 0 5
no trend 15 14 13 14 14 9 15 10 12 116
downward trend 1 1 2 2 3 2 2 5 4 22
Celtic Sea upward trend 0 0 1 1 1 0 1 0 0 4
no trend 2 2 1 1 1 1 1 2 2 13
downward trend 0 0 0 0 0 0 0 0 0 0
total upward trend 1 0 2 3 2 2 2 0 0 12
no trend 26 22 23 23 23 16 23 21 23 200
downward trend 2 2 3 3 3 3 3 6 5 30
4 Iberian Sea upward trend 0 2 0 0 0 0 0 0 0 2
no trend 12 10 12 10 13 10 13 13 9 102
downward trend 3 3 3 5 2 5 2 2 6 31
Gulf of Cadiz upward trend 0 0 0 0 0 0 0 0 0 0
no trend 11 11 10 10 9 12 6 13 6 88
downward trend 3 3 4 4 5 2 8 1 8 38
total upward trend 0 2 0 0 0 0 0 0 0 2
no trend 23 21 22 20 22 22 19 26 15 190
downward trend 6 6 7 9 7 7 10 3 14 69


Trend summary (proportions)

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

OSPAR region MIME region status PA ANT FLU PYR BAA CHR BAP BGHIP ICDP total
2 Northern North Sea upward trend 4 5 8 4 9 5 9 9 9 7
no trend 92 85 80 84 77 86 77 77 86 83
downward trend 4 10 12 12 14 9 14 14 5 10
Southern North Sea upward trend 3 5 5 3 0 3 0 0 0 2
no trend 69 73 76 74 82 74 74 62 72 73
downward trend 28 22 19 23 18 23 26 38 28 25
Channel upward trend 0 0 0 0 0 0 0 0 0 0
no trend 83 100 83 83 83 67 83 67 83 82
downward trend 17 0 17 17 17 33 17 33 17 18
total upward trend 3 5 6 3 3 3 3 3 3 4
no trend 79 79 78 79 80 78 76 67 78 77
downward trend 18 16 16 18 17 19 21 30 19 19
3 Irish and Scottish West Coast upward trend 0 0 0 10 11 0 11 0 0 4
no trend 90 86 90 80 89 86 78 90 90 86
downward trend 10 14 10 10 0 14 11 10 10 10
Irish Sea upward trend 6 0 6 6 0 16 0 0 0 4
no trend 88 93 81 82 82 69 88 67 75 81
downward trend 6 7 13 12 18 15 12 33 25 15
Celtic Sea upward trend 0 0 50 50 50 0 50 0 0 24
no trend 100 100 50 50 50 100 50 100 100 76
downward trend 0 0 0 0 0 0 0 0 0 0
total upward trend 3 0 7 11 7 10 7 0 0 5
no trend 90 92 82 79 82 76 82 78 82 83
downward trend 7 8 11 10 11 14 11 22 18 12
4 Iberian Sea upward trend 0 13 0 0 0 0 0 0 0 1
no trend 80 67 80 67 87 67 87 87 60 76
downward trend 20 20 20 33 13 33 13 13 40 23
Gulf of Cadiz upward trend 0 0 0 0 0 0 0 0 0 0
no trend 79 79 71 71 64 86 43 93 43 70
downward trend 21 21 29 29 36 14 57 7 57 30
total upward trend 0 7 0 0 0 0 0 0 0 1
no trend 79 72 76 69 76 76 66 90 52 73
downward trend 21 21 24 31 24 24 34 10 48 26


Status summary (numbers)

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

OSPAR region MIME region status PA ANT FLU PYR BAA CHR BAP BGHIP ICDP total
2 Northern North Sea blue 11 10 10 9 9 9 10 11 11 90
green 8 6 14 15 11 14 13 0 0 81
orange 0 0 0 0 0 0 0 13 13 26
red 7 10 2 2 4 0 1 0 0 26
Southern North Sea blue 5 2 5 4 5 1 13 26 31 92
green 39 43 43 44 43 46 35 0 0 293
orange 0 0 0 0 0 0 0 25 20 45
red 7 6 3 3 3 2 3 0 0 27
Channel blue 3 0 2 1 1 1 1 4 6 19
green 28 10 32 32 23 30 30 0 0 185
orange 0 0 0 0 0 0 0 34 31 65
red 9 21 6 7 16 6 9 0 0 74
total blue 19 12 17 14 15 11 24 41 48 201
green 75 59 89 91 77 90 78 0 0 559
orange 0 0 0 0 0 0 0 72 64 136
red 23 37 11 12 23 8 13 0 0 127
3 Irish and Scottish West Coast blue 4 5 5 4 3 3 6 7 7 44
green 5 3 4 5 6 7 4 0 0 34
orange 0 0 0 0 0 0 0 3 3 6
red 1 2 1 1 1 0 0 0 0 6
Irish Sea blue 0 0 0 0 0 0 0 1 2 3
green 12 19 21 20 17 19 20 0 0 128
orange 0 0 0 0 0 0 0 22 21 43
red 11 4 2 3 6 3 3 0 0 32
Celtic Sea blue 0 0 0 0 0 0 0 0 0 0
green 0 0 1 1 0 1 1 0 0 4
orange 0 0 0 0 0 0 0 2 2 4
red 2 2 1 1 2 0 1 0 0 9
total blue 4 5 5 4 3 3 6 8 9 47
green 17 22 26 26 23 27 25 0 0 166
orange 0 0 0 0 0 0 0 27 26 53
red 14 8 4 5 9 3 4 0 0 47
4 Iberian Sea blue 0 0 0 0 0 0 0 0 0 0
green 11 13 13 15 13 15 15 0 0 95
orange 0 0 0 0 0 0 0 15 15 30
red 4 2 2 0 2 0 0 0 0 10
Gulf of Cadiz blue 13 7 12 10 12 13 13 11 13 104
green 1 7 2 4 2 1 1 0 0 18
orange 0 0 0 0 0 0 0 3 1 4
red 0 0 0 0 0 0 0 0 0 0
total blue 13 7 12 10 12 13 13 11 13 104
green 12 20 15 19 15 16 16 0 0 113
orange 0 0 0 0 0 0 0 18 16 34
red 4 2 2 0 2 0 0 0 0 10


Status summary (proportions)

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

OSPAR region MIME region status PA ANT FLU PYR BAA CHR BAP BGHIP ICDP total
2 Northern North Sea blue 42 39 38 34 37 39 42 46 46 40
green 31 23 54 58 46 61 54 0 0 36
orange 0 0 0 0 0 0 0 54 54 12
red 27 38 8 8 17 0 4 0 0 12
Southern North Sea blue 10 4 10 8 10 2 25 51 61 20
green 76 84 84 86 84 94 69 0 0 64
orange 0 0 0 0 0 0 0 49 39 10
red 14 12 6 6 6 4 6 0 0 6
Channel blue 8 0 5 2 2 3 3 11 16 5
green 70 32 80 80 58 81 75 0 0 54
orange 0 0 0 0 0 0 0 89 84 19
red 22 68 15 18 40 16 22 0 0 22
total blue 16 11 15 12 13 10 21 36 43 20
green 64 55 76 78 67 83 68 0 0 55
orange 0 0 0 0 0 0 0 64 57 13
red 20 34 9 10 20 7 11 0 0 12
3 Irish and Scottish West Coast blue 40 50 50 40 30 30 60 70 70 49
green 50 30 40 50 60 70 40 0 0 38
orange 0 0 0 0 0 0 0 30 30 6
red 10 20 10 10 10 0 0 0 0 7
Irish Sea blue 0 0 0 0 0 0 0 4 9 1
green 52 83 91 87 74 86 87 0 0 62
orange 0 0 0 0 0 0 0 96 91 21
red 48 17 9 13 26 14 13 0 0 16
Celtic Sea blue 0 0 0 0 0 0 0 0 0 0
green 0 0 50 50 0 100 50 0 0 23
orange 0 0 0 0 0 0 0 100 100 24
red 100 100 50 50 100 0 50 0 0 53
total blue 11 14 14 12 8 9 17 23 26 15
green 49 63 74 74 66 82 71 0 0 53
orange 0 0 0 0 0 0 0 77 74 17
red 40 23 12 14 26 9 12 0 0 15
4 Iberian Sea blue 0 0 0 0 0 0 0 0 0 0
green 73 87 87 100 87 100 100 0 0 70
orange 0 0 0 0 0 0 0 100 100 22
red 27 13 13 0 13 0 0 0 0 8
Gulf of Cadiz blue 93 50 86 71 86 93 93 79 93 83
green 7 50 14 29 14 7 7 0 0 14
orange 0 0 0 0 0 0 0 21 7 3
red 0 0 0 0 0 0 0 0 0 0
total blue 45 24 41 34 41 45 45 38 45 40
green 41 69 52 66 52 55 55 0 0 43
orange 0 0 0 0 0 0 0 62 55 13
red 14 7 7 0 7 0 0 0 0 4


MIME 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.

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 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: PAH + region.PAH + station + trend estimation variation + residual variation

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

The random model has five terms:

  • PAH allows for variation in trend between PAHs common to all regions
  • region.PAH allows for additional variation in trend between PAHs within regions
  • station allows for variation in trend between stations common to all PAHs
  • 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 meta-analysis is restricted to time series from monitoring stations that are classified as ‘representative’. ‘Baseline’ stations (those with near pristine conditions or only subject to very diffuse inputs) are omitted because any trends there will likely be caused by different processes to those at representative stations. Similarly ‘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
  • PAHs with trend information for at least three stations (over all regions): PAHs are treated as random effects in the meta-anlaysis, so information about trends in one PAH can be ‘borrowed’ from the trend information in the other PAHs

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 criterion might vary between PAHs and time series. Essentially the same linear mixed model as for trends is then fitted:

  • response: status (mean log concentration - log assessment concentration)
  • fixed model: region
  • random model: PAH + region.PAH + 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 PAHs 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 magenta circles are stations where there is a trend assessment for at least one PAH, and the cyan 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: Celtic Sea
  • status: Celtic Sea, Iberian Sea


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 (averaged over PAHs) with pointwise 95% confidence limits
  • Regional trends by PAH: regional trend estimates for each PAH with pointwise 95% confidence limits plotted by PAH
  • Regional trends by region: regional trend estimates for each PAH with pointwise 95% confidence limits plotted by biogeographic region
  • Individual time series: the trend estimates from the individual time series on which the regional assessment is based. The estimates from 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 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 (averaged over PAHs) and the regional trend by PAH.


    Regional trends


    Regional trends by PAH


    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 trend se lower upper % yearly change %yc lower %yc upper
    Northern North Sea -1.61 1.00 -3.56 0.34 -1.59 -3.50 0.35
    Southern North Sea -1.19 0.74 -2.64 0.27 -1.18 -2.61 0.27
    Channel -5.33 2.09 -9.43 -1.22 -5.19 -9.00 -1.22
    Irish and Scottish West Coast 2.65 1.71 -0.71 6.00 2.68 -0.70 6.18
    Irish Sea -0.49 1.29 -3.02 2.04 -0.49 -2.98 2.06
    Gulf of Cadiz -6.13 1.51 -9.08 -3.18 -5.94 -8.68 -3.13


    Estimates by region and PAH

    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 PAH trend se lower upper % yearly change %yc lower %yc upper
    Northern North Sea PA -1.59 1.00 -3.55 0.37 -1.58 -3.49 0.37
    ANT -1.57 1.00 -3.54 0.39 -1.56 -3.47 0.39
    FLU -1.62 1.00 -3.58 0.34 -1.60 -3.51 0.34
    PYR -1.64 1.00 -3.60 0.32 -1.62 -3.53 0.33
    BAA -1.51 1.00 -3.47 0.45 -1.50 -3.41 0.45
    CHR -1.48 1.00 -3.44 0.48 -1.47 -3.38 0.48
    BAP -1.71 1.00 -3.67 0.25 -1.70 -3.61 0.25
    BGHIP -1.68 1.00 -3.64 0.28 -1.67 -3.57 0.28
    ICDP -1.67 1.00 -3.63 0.29 -1.66 -3.57 0.29
    Southern North Sea PA -1.17 0.75 -2.64 0.30 -1.16 -2.60 0.30
    ANT -1.15 0.75 -2.62 0.32 -1.15 -2.59 0.32
    FLU -1.19 0.75 -2.66 0.27 -1.19 -2.63 0.27
    PYR -1.21 0.75 -2.68 0.25 -1.21 -2.65 0.26
    BAA -1.09 0.75 -2.56 0.38 -1.08 -2.53 0.38
    CHR -1.06 0.75 -2.53 0.41 -1.05 -2.49 0.41
    BAP -1.29 0.75 -2.76 0.18 -1.28 -2.72 0.18
    BGHIP -1.26 0.75 -2.72 0.21 -1.25 -2.69 0.21
    ICDP -1.25 0.75 -2.72 0.22 -1.24 -2.68 0.22
    Channel PA -5.31 2.10 -9.42 -1.20 -5.17 -8.99 -1.20
    ANT -5.30 2.10 -9.40 -1.19 -5.16 -8.98 -1.18
    FLU -5.34 2.10 -9.44 -1.23 -5.20 -9.01 -1.22
    PYR -5.36 2.10 -9.46 -1.25 -5.22 -9.03 -1.24
    BAA -5.23 2.10 -9.34 -1.12 -5.10 -8.92 -1.12
    CHR -5.20 2.10 -9.31 -1.09 -5.07 -8.89 -1.08
    BAP -5.43 2.10 -9.54 -1.32 -5.29 -9.10 -1.31
    BGHIP -5.40 2.10 -9.51 -1.29 -5.26 -9.07 -1.28
    ICDP -5.39 2.10 -9.50 -1.28 -5.25 -9.06 -1.28
    Irish and Scottish West Coast PA 2.66 1.71 -0.69 6.02 2.70 -0.69 6.21
    ANT 2.68 1.71 -0.68 6.04 2.72 -0.68 6.23
    FLU 2.64 1.71 -0.72 6.00 2.68 -0.71 6.18
    PYR 2.62 1.71 -0.74 5.98 2.65 -0.73 6.16
    BAA 2.74 1.71 -0.62 6.10 2.78 -0.61 6.29
    CHR 2.78 1.71 -0.58 6.14 2.82 -0.58 6.33
    BAP 2.55 1.71 -0.81 5.90 2.58 -0.81 6.08
    BGHIP 2.58 1.71 -0.78 5.93 2.61 -0.78 6.11
    ICDP 2.58 1.71 -0.77 5.94 2.62 -0.77 6.12
    Irish Sea PA -0.48 1.29 -3.01 2.06 -0.47 -2.97 2.08
    ANT -0.46 1.29 -3.00 2.08 -0.46 -2.95 2.10
    FLU -0.50 1.29 -3.04 2.03 -0.50 -2.99 2.06
    PYR -0.52 1.29 -3.05 2.01 -0.52 -3.01 2.04
    BAA -0.40 1.29 -2.93 2.14 -0.40 -2.89 2.16
    CHR -0.36 1.29 -2.90 2.17 -0.36 -2.86 2.20
    BAP -0.59 1.29 -3.13 1.94 -0.59 -3.08 1.96
    BGHIP -0.56 1.29 -3.10 1.97 -0.56 -3.05 1.99
    ICDP -0.56 1.29 -3.09 1.98 -0.55 -3.04 2.00
    Gulf of Cadiz PA -6.11 1.51 -9.07 -3.15 -5.93 -8.67 -3.10
    ANT -6.09 1.51 -9.05 -3.14 -5.91 -8.65 -3.09
    FLU -6.13 1.51 -9.09 -3.18 -5.95 -8.69 -3.13
    PYR -6.15 1.51 -9.11 -3.20 -5.97 -8.71 -3.15
    BAA -6.03 1.51 -8.99 -3.07 -5.85 -8.60 -3.03
    CHR -6.00 1.51 -8.95 -3.04 -5.82 -8.57 -3.00
    BAP -6.23 1.51 -9.19 -3.27 -6.04 -8.78 -3.22
    BGHIP -6.20 1.51 -9.15 -3.24 -6.01 -8.75 -3.19
    ICDP -6.19 1.51 -9.15 -3.24 -6.00 -8.74 -3.18


    Regional status compared to the Effects Range Low (ERL)

    The first 4 tabs show:

  • Regional status: estimates of the regional status (averaged over PAHs) with pointwise upper one-sided 95% confidence limits
  • Regional status by PAH: regional status estimates for each PAH with pointwise upper one-sided 95% confidence limits plotted by PAH
  • Regional status by region: regional status estimates for each PAH with pointwise upper one-sided 95% confidence limits plotted by biogeographic region
  • Individual time series: the status estimates from the individual time series on which the regional assessment is based. The estimates from 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 ERL
    • orange: there is no ERL and the mean concentration is not significantly below the BAC
    • red: the estimate of the mean concentration is not significantly below the ERL

    Note that to see why some points are 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 ERL with the assessment of status relative to the BAC because the ratio of the BAC to the ERL can vary between PAHs, between regions and, for biota, between species.

    The final 2 tabs show the estimates of the regional status (averaged over PAHs) and the regional status by PAH.


    Regional status


    Regional status by PAH


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


    MIME region status se upper concentration conc upper
    Northern North Sea -2.23 0.25 -1.83 0.11 0.16
    Southern North Sea -1.97 0.19 -1.66 0.14 0.19
    Channel -2.06 0.21 -1.71 0.13 0.18
    Irish and Scottish West Coast -3.31 0.38 -2.69 0.04 0.07
    Irish Sea -1.27 0.26 -0.84 0.28 0.43
    Gulf of Cadiz -4.62 0.32 -4.09 0.01 0.02


    Estimates by region and PAH

    This table shows the estimates of regional status by determinand:

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


    MIME region PAH status se upper concentration conc upper
    Northern North Sea PA -1.67 0.23 -1.30 0.19 0.27
    ANT -2.06 0.23 -1.69 0.13 0.18
    FLU -2.40 0.23 -2.02 0.09 0.13
    PYR -2.59 0.23 -2.22 0.07 0.11
    BAA -2.12 0.23 -1.75 0.12 0.17
    CHR -2.36 0.23 -1.98 0.09 0.14
    BAP -2.43 0.23 -2.06 0.09 0.13
    BGHIP
    ICDP
    Southern North Sea PA -1.36 0.16 -1.10 0.26 0.33
    ANT -1.80 0.16 -1.53 0.17 0.22
    FLU -1.99 0.16 -1.72 0.14 0.18
    PYR -2.34 0.16 -2.08 0.10 0.13
    BAA -1.95 0.16 -1.68 0.14 0.19
    CHR -2.12 0.16 -1.86 0.12 0.16
    BAP -2.25 0.16 -1.99 0.11 0.14
    BGHIP
    ICDP
    Channel PA -1.78 0.19 -1.47 0.17 0.23
    ANT -1.98 0.19 -1.66 0.14 0.19
    FLU -2.13 0.19 -1.83 0.12 0.16
    PYR -2.45 0.19 -2.14 0.09 0.12
    BAA -1.80 0.19 -1.49 0.17 0.23
    CHR -2.16 0.19 -1.85 0.12 0.16
    BAP -2.11 0.19 -1.80 0.12 0.17
    BGHIP
    ICDP
    Irish and Scottish West Coast PA -2.60 0.37 -1.99 0.07 0.14
    ANT -3.60 0.37 -2.99 0.03 0.05
    FLU -3.37 0.37 -2.76 0.03 0.06
    PYR -3.75 0.37 -3.15 0.02 0.04
    BAA -3.13 0.37 -2.52 0.04 0.08
    CHR -3.30 0.37 -2.69 0.04 0.07
    BAP -3.45 0.37 -2.84 0.03 0.06
    BGHIP
    ICDP
    Irish Sea PA -0.67 0.24 -0.28 0.51 0.76
    ANT -1.33 0.24 -0.94 0.26 0.39
    FLU -1.38 0.24 -0.98 0.25 0.37
    PYR -1.66 0.24 -1.26 0.19 0.28
    BAA -1.08 0.24 -0.69 0.34 0.50
    CHR -1.30 0.24 -0.91 0.27 0.40
    BAP -1.45 0.24 -1.06 0.23 0.35
    BGHIP
    ICDP
    Gulf of Cadiz PA -4.19 0.31 -3.69 0.02 0.02
    ANT -4.52 0.31 -4.02 0.01 0.02
    FLU -4.60 0.31 -4.10 0.01 0.02
    PYR -4.78 0.31 -4.27 0.01 0.01
    BAA -4.43 0.31 -3.93 0.01 0.02
    CHR -4.86 0.31 -4.35 0.01 0.01
    BAP -4.93 0.31 -4.43 0.01 0.01
    BGHIP
    ICDP


    Regional status compared to the Background Assessment Concentration (BAC)

    The first 4 tabs show:

  • Regional status: estimates of the regional status (averaged over PAHs) with pointwise upper one-sided 95% confidence limits
  • Regional status by PAH: regional status estimates for each PAH with pointwise upper one-sided 95% confidence limits plotted by PAH
  • Regional status by region: regional status estimates for each PAH with pointwise upper one-sided 95% confidence limits plotted by biogeographic region
  • Individual time series: the status estimates from the individual time series on which the regional assessment is based. The estimates from 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 Effects Range Low (ERL)
    • orange: there is no ERL and the mean concentration is not significantly below the BAC
    • red: the estimate of the mean concentration is not significantly below the ERL

    The final 2 tabs show the estimates of the regional status (averaged over PAHs) and the regional status by PAH.


    Regional status


    Regional status by PAH


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


    MIME region status se upper concentration conc upper
    Northern North Sea 0.38 0.24 0.78 1.46 2.18
    Southern North Sea 0.53 0.19 0.85 1.69 2.33
    Channel 0.41 0.21 0.75 1.50 2.12
    Irish and Scottish West Coast -0.70 0.36 -0.10 0.50 0.90
    Irish Sea 1.22 0.25 1.64 3.40 5.17
    Gulf of Cadiz -0.82 0.31 -0.31 0.44 0.73


    Estimates by region and PAH

    This table shows the estimates of regional status 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 PAH status se upper concentration conc upper
    Northern North Sea PA 0.36 0.22 0.71 1.43 2.04
    ANT 0.82 0.22 1.17 2.27 3.24
    FLU 0.39 0.21 0.74 1.47 2.09
    PYR 0.78 0.22 1.13 2.17 3.09
    BAA 0.73 0.22 1.08 2.07 2.95
    CHR 0.59 0.22 0.95 1.80 2.57
    BAP 0.28 0.22 0.64 1.32 1.89
    BGHIP -0.17 0.22 0.18 0.84 1.20
    ICDP -0.35 0.22 0.01 0.71 1.01
    Southern North Sea PA 0.65 0.15 0.90 1.91 2.46
    ANT 1.05 0.15 1.30 2.85 3.67
    FLU 0.74 0.15 0.99 2.10 2.70
    PYR 0.97 0.15 1.22 2.65 3.40
    BAA 0.83 0.15 1.08 2.29 2.94
    CHR 0.82 0.15 1.07 2.26 2.91
    BAP 0.39 0.15 0.65 1.48 1.91
    BGHIP -0.27 0.15 -0.02 0.76 0.98
    ICDP -0.43 0.15 -0.18 0.65 0.83
    Channel PA 0.21 0.18 0.50 1.24 1.66
    ANT 0.86 0.19 1.17 2.36 3.21
    FLU 0.59 0.18 0.88 1.80 2.42
    PYR 0.86 0.18 1.15 2.35 3.15
    BAA 0.97 0.18 1.27 2.64 3.55
    CHR 0.77 0.18 1.07 2.17 2.91
    BAP 0.56 0.18 0.85 1.75 2.35
    BGHIP -0.56 0.18 -0.26 0.57 0.77
    ICDP -0.61 0.18 -0.32 0.54 0.73
    Irish and Scottish West Coast PA -0.60 0.35 -0.02 0.55 0.98
    ANT -0.87 0.35 -0.29 0.42 0.75
    FLU -0.67 0.35 -0.09 0.51 0.92
    PYR -0.48 0.35 0.10 0.62 1.10
    BAA -0.38 0.35 0.20 0.68 1.22
    CHR -0.34 0.35 0.24 0.71 1.27
    BAP -0.81 0.35 -0.23 0.44 0.79
    BGHIP -0.99 0.35 -0.42 0.37 0.66
    ICDP -1.12 0.35 -0.54 0.33 0.58
    Irish Sea PA 1.33 0.23 1.70 3.77 5.49
    ANT 1.49 0.23 1.86 4.42 6.43
    FLU 1.33 0.23 1.70 3.77 5.48
    PYR 1.67 0.23 2.04 5.31 7.73
    BAA 1.66 0.23 2.04 5.26 7.66
    CHR 1.61 0.23 1.99 5.01 7.28
    BAP 1.20 0.23 1.57 3.31 4.83
    BGHIP 0.44 0.23 0.81 1.55 2.25
    ICDP 0.31 0.23 0.69 1.36 1.99
    Gulf of Cadiz PA -0.72 0.29 -0.25 0.49 0.78
    ANT -0.65 0.29 -0.16 0.52 0.85
    FLU -0.86 0.29 -0.38 0.42 0.68
    PYR -0.66 0.29 -0.18 0.52 0.83
    BAA -0.81 0.29 -0.33 0.45 0.72
    CHR -0.98 0.29 -0.49 0.38 0.61
    BAP -1.00 0.29 -0.52 0.37 0.59
    BGHIP -0.71 0.29 -0.23 0.49 0.79
    ICDP -1.00 0.29 -0.52 0.37 0.60


    PAH profiles

    The profile of concentrations across PAHs 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 by restricted maximum likelihood:

    • response: mean log concentration
    • fixed model: region
    • random model: PAH + region.PAH + station + estimation variation + 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 estimated PAH concentration profiles by region are shown below with pointwise 95% confidence limits. The units are ug/kg dw.