Regional assessment of status and trends in metal concentrations in sediment

  • Overview
  • Summary of individual time series results
  • Regional assessment - methods
  • Regional assessment - availability of time series
  • Regional trends
  • Regional status compared to the Effects Range Low (ERL)
  • Regional status compared to the Background Assessment Concentration (BAC)

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 metal concentrations in sediment, where the metals are AS, CD, CR, CU, PB, HG, NI, ZN. 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 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 metal 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. 8 of the 1433 metal 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 metals. The purple circles are stations where there is a trend assessment for at least one metal, 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 metal 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)
  • orange: there is no ERL and the mean concentration is not significantly below the BAC
  • red: the mean concentration is not signficantly below the ERL
  • 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, orange or red status in each MIME and OSPAR region
  • the same information presented as proportions

Note that:

  • BACs for the Iberian Sea and Gulf of Cadiz have only been developed for cadmium, lead and mercury
  • chromium time series are only assessed against the ERL (as there is either no BAC, or the BAC equals the ERL)
  • arsenic and nickel time series are only assessed against the BAC; the ERL is not used because it is lower than the BAC and is regarded as too precautionary


Stations


AS


CD


CR


CU


PB


HG


NI


ZN


Trend summary (numbers)

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

OSPAR region MIME region status AS CD CR CU PB HG NI ZN total
2 Northern North Sea upward trend 2 1 1 1 1 0 1 0 7
no trend 9 9 10 9 10 7 10 11 75
downward trend 0 1 2 2 2 3 2 2 14
Southern North Sea upward trend 3 0 1 2 0 0 0 0 6
no trend 45 35 52 33 46 31 50 37 329
downward trend 7 27 10 28 18 30 14 22 156
Channel upward trend 1 2 0 0 0 0 0 1 4
no trend 2 1 3 2 2 3 3 2 18
downward trend 0 0 0 1 1 0 0 0 2
total upward trend 6 3 2 3 1 0 1 1 17
no trend 56 45 65 44 58 41 63 50 422
downward trend 7 28 12 31 21 33 16 24 172
3 Irish and Scottish West Coast upward trend 0 1 0 0 0 0 0 0 1
no trend 6 4 6 6 5 5 6 6 44
downward trend 0 0 0 0 1 1 0 0 2
Irish Sea upward trend 2 0 1 0 0 0 0 0 3
no trend 11 11 10 10 9 8 12 11 82
downward trend 0 1 2 3 4 4 1 2 17
Celtic Sea upward trend 0 1 2 0 1 0 2 1 7
no trend 2 1 0 2 1 2 0 1 9
downward trend 0 0 0 0 0 0 0 0 0
total upward trend 2 2 3 0 1 0 2 1 11
no trend 19 16 16 18 15 15 18 18 135
downward trend 0 1 2 3 5 5 1 2 19
4 Iberian Sea upward trend 0 0 0 0 0 0 0 0 0
no trend 2 2 2 2 2 2 2 1 15
downward trend 0 0 0 0 0 0 0 1 1
total upward trend 0 0 0 0 0 0 0 0 0
no trend 2 2 2 2 2 2 2 1 15
downward trend 0 0 0 0 0 0 0 1 1


Trend summary (proportions)

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

OSPAR region MIME region status AS CD CR CU PB HG NI ZN total
2 Northern North Sea upward trend 18 9 8 8 8 0 8 0 7
no trend 82 82 77 75 77 70 77 85 78
downward trend 0 9 15 17 15 30 15 15 15
Southern North Sea upward trend 5 0 2 3 0 0 0 0 1
no trend 82 56 82 52 72 51 78 63 67
downward trend 13 44 16 45 28 49 22 37 32
Channel upward trend 33 67 0 0 0 0 0 33 17
no trend 67 33 100 67 67 100 100 67 75
downward trend 0 0 0 33 33 0 0 0 8
total upward trend 9 4 3 4 1 0 1 1 3
no trend 81 59 82 56 73 55 79 67 69
downward trend 10 37 15 40 26 45 20 32 28
3 Irish and Scottish West Coast upward trend 0 20 0 0 0 0 0 0 2
no trend 100 80 100 100 83 83 100 100 94
downward trend 0 0 0 0 17 17 0 0 4
Irish Sea upward trend 15 0 8 0 0 0 0 0 3
no trend 85 92 77 77 69 67 92 85 80
downward trend 0 8 15 23 31 33 8 15 17
Celtic Sea upward trend 0 50 100 0 50 0 100 50 44
no trend 100 50 0 100 50 100 0 50 56
downward trend 0 0 0 0 0 0 0 0 0
total upward trend 10 11 14 0 5 0 9 5 7
no trend 90 84 76 86 71 75 86 86 82
downward trend 0 5 10 14 24 25 5 9 11
4 Iberian Sea upward trend 0 0 0 0 0 0 0 0 0
no trend 100 100 100 100 100 100 100 50 94
downward trend 0 0 0 0 0 0 0 50 6
total upward trend 0 0 0 0 0 0 0 0 0
no trend 100 100 100 100 100 100 100 50 94
downward trend 0 0 0 0 0 0 0 50 6


Status summary (numbers)

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

OSPAR region MIME region status AS CD CR CU PB HG NI ZN total
2 Northern North Sea blue 9 11 0 10 10 7 10 11 68
green 0 4 9 2 0 3 0 1 19
orange 4 0 0 0 0 0 5 0 9
red 0 0 6 2 5 5 0 3 21
Southern North Sea blue 22 15 0 38 1 4 26 5 111
green 0 49 10 15 3 12 0 7 96
orange 43 0 0 0 0 0 45 0 88
red 0 5 59 16 65 53 0 51 249
Channel blue 0 8 0 6 2 4 2 3 25
green 0 21 0 7 5 8 0 9 50
orange 4 0 0 0 0 0 39 0 43
red 0 12 41 28 31 29 0 29 170
total blue 31 34 0 54 13 15 38 19 204
green 0 74 19 24 8 23 0 17 165
orange 51 0 0 0 0 0 89 0 140
red 0 17 106 46 101 87 0 83 440
3 Irish and Scottish West Coast blue 6 5 0 4 5 5 0 4 29
green 0 1 0 1 1 1 0 0 4
orange 0 0 0 0 0 0 6 0 6
red 0 0 6 1 0 0 0 2 9
Irish Sea blue 11 10 0 7 3 2 1 3 37
green 0 6 1 1 3 5 0 4 20
orange 5 0 0 0 0 0 15 0 20
red 0 0 15 8 10 9 0 9 51
Celtic Sea blue 1 0 0 1 0 0 0 0 2
green 0 3 0 0 0 1 0 0 4
orange 1 0 0 0 0 0 3 0 4
red 0 0 3 2 3 2 0 3 13
total blue 18 15 0 12 8 7 1 7 68
green 0 10 1 2 4 7 0 4 28
orange 6 0 0 0 0 0 24 0 30
red 0 0 24 11 13 11 0 14 73
4 Iberian Sea blue 0 18 0 0 8 14 0 0 40
green 0 18 25 29 14 2 0 27 115
orange 0 0 0 0 0 0 0 0 0
red 0 0 9 7 14 20 0 9 59
total blue 0 18 0 0 8 14 0 0 40
green 0 18 25 29 14 2 0 27 115
orange 0 0 0 0 0 0 0 0 0
red 0 0 9 7 14 20 0 9 59


Status summary (proportions)

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

OSPAR region MIME region status AS CD CR CU PB HG NI ZN total
2 Northern North Sea blue 69 73 0 72 67 47 67 73 58
green 0 27 60 14 0 20 0 7 16
orange 31 0 0 0 0 0 33 0 8
red 0 0 40 14 33 33 0 20 18
Southern North Sea blue 34 22 0 55 2 6 37 8 20
green 0 71 14 22 4 17 0 11 18
orange 66 0 0 0 0 0 63 0 16
red 0 7 86 23 94 77 0 81 46
Channel blue 0 20 0 15 5 10 5 7 9
green 0 51 0 17 13 19 0 22 17
orange 100 0 0 0 0 0 95 0 15
red 0 29 100 68 82 71 0 71 59
total blue 38 27 0 44 11 12 30 16 22
green 0 59 15 19 6 18 0 14 17
orange 62 0 0 0 0 0 70 0 15
red 0 14 85 37 83 70 0 70 46
3 Irish and Scottish West Coast blue 100 83 0 67 83 83 0 67 60
green 0 17 0 16 17 17 0 0 8
orange 0 0 0 0 0 0 100 0 13
red 0 0 100 17 0 0 0 33 19
Irish Sea blue 69 62 0 44 19 13 6 19 29
green 0 38 6 6 19 31 0 25 15
orange 31 0 0 0 0 0 94 0 16
red 0 0 94 50 62 56 0 56 40
Celtic Sea blue 50 0 0 33 0 0 0 0 9
green 0 100 0 0 0 33 0 0 17
orange 50 0 0 0 0 0 100 0 17
red 0 0 100 67 100 67 0 100 57
total blue 75 60 0 48 32 28 4 28 34
green 0 40 4 8 16 28 0 16 14
orange 25 0 0 0 0 0 96 0 15
red 0 0 96 44 52 44 0 56 37
4 Iberian Sea blue 50 0 0 22 39 0 19
green 50 74 81 39 5 75 54
orange 0 0 0 0 0 0 0
red 0 26 19 39 56 25 27
total blue 50 0 0 22 39 0 19
green 50 74 81 39 5 75 54
orange 0 0 0 0 0 0 0
red 0 26 19 39 56 25 27


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.metal
  • random model: station + trend estimation variation + residual variation

The fixed model means that a separate regional trend is estimated for each metal. The random model has three terms:

  • station allows for variation in trend between stations common to all metals
  • 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’ 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 region and metal combinations 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.

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 metals and regions. Essentially the same linear mixed model as for trends is then fitted:

  • response: status (mean log concentration - log assessment concentration)
  • fixed model: region.metal
  • 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 and metal combinations with at least three status stations with good geographic spread.

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 metal, 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: Celtic Sea, Iberian Sea
  • status:


OSPAR region 1


OSPAR region 2


OSPAR region 3


OSPAR region 4


Regional trends

The first 3 tabs show:

  • Regional trends by metal: regional trend estimates for each metal with pointwise 95% confidence intervals plotted by metal
  • Regional trends by region: regional trend estimates for each metal 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 tab shows the estimates of the regional trend by metal.


Regional trends by metal


Regional trends by region


Individual time series


Estimates by region and metal

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 metal trend se lower upper % yearly change %yc lower %yc upper
Northern North Sea AS 1.48 0.71 0.09 2.87 1.49 0.09 2.91
CD 0.06 0.99 -1.89 2.01 0.06 -1.87 2.03
CR -0.92 0.67 -2.22 0.39 -0.91 -2.20 0.39
CU -1.86 0.83 -3.48 -0.24 -1.84 -3.42 -0.24
PB -1.08 0.66 -2.37 0.21 -1.08 -2.34 0.21
HG -2.87 0.90 -4.63 -1.11 -2.83 -4.52 -1.10
NI -0.71 0.67 -2.02 0.61 -0.70 -2.00 0.62
ZN -1.41 0.68 -2.75 -0.08 -1.40 -2.71 -0.08
Southern North Sea AS -1.10 0.29 -1.66 -0.54 -1.09 -1.65 -0.54
CD -2.61 0.29 -3.18 -2.04 -2.58 -3.13 -2.02
CR -1.01 0.27 -1.55 -0.48 -1.01 -1.53 -0.48
CU -1.59 0.28 -2.13 -1.04 -1.58 -2.11 -1.04
PB -1.95 0.28 -2.50 -1.40 -1.93 -2.47 -1.39
HG -2.84 0.29 -3.40 -2.28 -2.80 -3.35 -2.26
NI -1.15 0.27 -1.68 -0.61 -1.14 -1.67 -0.61
ZN -1.54 0.28 -2.09 -0.99 -1.53 -2.07 -0.98
Channel AS 0.26 1.42 -2.53 3.05 0.26 -2.49 3.10
CD 4.75 1.89 1.04 8.47 4.87 1.05 8.84
CR 0.14 1.41 -2.63 2.91 0.14 -2.59 2.95
CU -0.21 1.41 -2.98 2.57 -0.21 -2.93 2.60
PB -0.14 1.42 -2.93 2.65 -0.14 -2.89 2.69
HG -0.94 2.06 -4.98 3.09 -0.94 -4.86 3.14
NI 0.62 1.47 -2.26 3.50 0.62 -2.24 3.56
ZN 0.04 1.39 -2.68 2.75 0.04 -2.65 2.79
Irish and Scottish West Coast AS 1.04 1.14 -1.19 3.28 1.05 -1.19 3.33
CD 3.89 1.48 0.99 6.79 3.97 1.00 7.03
CR 0.12 1.02 -1.88 2.13 0.12 -1.86 2.15
CU -0.73 1.26 -3.19 1.74 -0.73 -3.14 1.75
PB -2.04 1.09 -4.18 0.09 -2.02 -4.09 0.09
HG -3.50 1.26 -5.96 -1.03 -3.44 -5.79 -1.03
NI -0.39 1.10 -2.54 1.76 -0.39 -2.51 1.78
ZN -0.68 1.20 -3.03 1.68 -0.68 -2.99 1.69
Irish Sea AS 0.77 0.65 -0.51 2.05 0.77 -0.51 2.07
CD 0.48 0.89 -1.27 2.23 0.48 -1.26 2.26
CR -0.71 0.66 -2.00 0.58 -0.71 -1.98 0.58
CU -2.61 0.74 -4.05 -1.16 -2.57 -3.97 -1.15
PB -1.89 0.69 -3.25 -0.53 -1.87 -3.20 -0.53
HG -2.86 0.82 -4.47 -1.24 -2.81 -4.37 -1.23
NI -0.88 0.68 -2.21 0.46 -0.87 -2.19 0.46
ZN -1.29 0.69 -2.64 0.06 -1.28 -2.61 0.06


Regional status compared to the Effects Range Low (ERL)

The first 3 tabs show:

  • Regional status by metal: regional status estimates for each metal with pointwise upper one-sided 95% confidence intervals plotted by metal
  • Regional status by region: regional status estimates for each metal 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 ERL
  • red: the mean concentration is not significantly below the ERL

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 ERL with the assessment of status relative to the BAC because the ratio of the BAC to the ERL can vary between metals and regions.

The final tab shows the estimates of the regional status by metal.


Regional status by metal


Regional status by region


Individual time series


Estimates by region and metal

This table shows the estimates of the regional trend 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 metal status se upper concentration conc upper
Northern North Sea AS
CD -2.11 0.18 -1.81 0.12 0.16
CR -0.38 0.16 -0.12 0.68 0.89
CU -1.27 0.17 -0.99 0.28 0.37
PB -0.38 0.16 -0.11 0.68 0.89
HG -0.72 0.17 -0.44 0.49 0.64
NI
ZN -0.98 0.16 -0.71 0.37 0.49
Southern North Sea AS
CD -1.18 0.08 -1.05 0.31 0.35
CR 0.07 0.08 0.20 1.07 1.22
CU -0.46 0.08 -0.34 0.63 0.71
PB 0.30 0.08 0.42 1.34 1.52
HG 0.14 0.08 0.27 1.15 1.30
NI
ZN 0.16 0.08 0.29 1.18 1.34
Channel AS
CD -1.01 0.10 -0.84 0.36 0.43
CR 0.32 0.10 0.49 1.37 1.63
CU -0.28 0.10 -0.11 0.75 0.89
PB -0.01 0.10 0.17 0.99 1.18
HG 0.10 0.10 0.27 1.10 1.30
NI
ZN -0.05 0.10 0.12 0.96 1.13
Irish and Scottish West Coast AS
CD -2.15 0.28 -1.70 0.12 0.18
CR 0.24 0.26 0.66 1.27 1.94
CU -0.65 0.26 -0.22 0.52 0.80
PB -0.75 0.26 -0.32 0.47 0.72
HG -1.29 0.27 -0.85 0.28 0.43
NI
ZN -0.51 0.26 -0.08 0.60 0.93
Irish Sea AS
CD -1.83 0.16 -1.56 0.16 0.21
CR 0.34 0.16 0.60 1.41 1.83
CU -0.40 0.16 -0.13 0.67 0.88
PB 0.01 0.16 0.27 1.01 1.32
HG -0.13 0.17 0.14 0.88 1.16
NI
ZN -0.14 0.16 0.12 0.87 1.13
Celtic Sea CD -1.41 0.37 -0.79 0.25 0.45
CR 0.12 0.37 0.72 1.12 2.06
CU -0.26 0.37 0.35 0.77 1.43
PB -0.15 0.36 0.45 0.86 1.57
HG -0.44 0.39 0.21 0.65 1.23
NI
ZN -0.09 0.36 0.51 0.91 1.67
Iberian Sea CD -2.45 0.11 -2.27 0.09 0.10
CR -0.63 0.11 -0.46 0.53 0.63
CU -1.25 0.11 -1.08 0.29 0.34
PB -0.51 0.11 -0.33 0.60 0.72
HG -0.50 0.11 -0.32 0.61 0.73
ZN -0.62 0.11 -0.44 0.54 0.64


Regional status compared to the Background Assessment Concentration (BAC)

The first 3 tabs show:

  • Regional status by metal: regional status estimates for each metal with pointwise upper one-sided 95% confidence intervals plotted by metal
  • Regional status by region: regional status estimates for each metal 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 Effects Range Low (ERL)
  • orange: there is no ERL and the mean concentration is not significantly below the BAC
  • red: the mean concentration is not significantly below the ERL

The final tab shows the estimates of the regional status by metal.


Regional status by metal


Regional status by region


Individual time series


Estimates by region and metal

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 metal status se upper concentration conc upper
Northern North Sea AS -0.73 0.17 -0.44 0.48 0.64
CD -0.75 0.18 -0.45 0.47 0.64
CR
CU -1.04 0.18 -0.75 0.35 0.47
PB -0.17 0.17 0.11 0.84 1.11
HG 0.04 0.18 0.33 1.04 1.39
NI -0.58 0.17 -0.30 0.56 0.74
ZN -0.78 0.17 -0.50 0.46 0.61
Southern North Sea AS 0.05 0.08 0.18 1.05 1.20
CD 0.18 0.08 0.31 1.20 1.37
CR
CU -0.23 0.08 -0.10 0.79 0.90
PB 0.51 0.08 0.64 1.67 1.90
HG 0.91 0.08 1.04 2.48 2.82
NI -0.07 0.08 0.05 0.93 1.05
ZN 0.38 0.08 0.51 1.46 1.67
Channel AS -0.06 0.24 0.33 0.94 1.39
CD 0.34 0.10 0.52 1.41 1.68
CR
CU -0.05 0.10 0.12 0.95 1.13
PB 0.21 0.11 0.38 1.23 1.47
HG 0.86 0.11 1.03 2.36 2.81
NI -0.08 0.10 0.09 0.93 1.10
ZN 0.16 0.10 0.33 1.17 1.39
Irish and Scottish West Coast AS -1.12 0.27 -0.69 0.32 0.50
CD -0.81 0.28 -0.34 0.44 0.71
CR
CU -0.42 0.27 0.02 0.65 1.02
PB -0.54 0.27 -0.10 0.58 0.91
HG -0.53 0.27 -0.08 0.59 0.93
NI 0.13 0.27 0.57 1.14 1.77
ZN -0.30 0.27 0.14 0.74 1.15
Irish Sea AS -0.59 0.16 -0.32 0.56 0.73
CD -0.47 0.17 -0.20 0.62 0.82
CR
CU -0.17 0.17 0.10 0.84 1.11
PB 0.22 0.16 0.49 1.25 1.64
HG 0.63 0.17 0.92 1.88 2.50
NI 0.14 0.16 0.41 1.15 1.51
ZN 0.06 0.16 0.33 1.06 1.39
Celtic Sea CD -0.05 0.38 0.58 0.95 1.79
CR
CU -0.03 0.38 0.60 0.97 1.83
PB 0.07 0.37 0.68 1.07 1.98
HG 0.32 0.40 0.98 1.38 2.67
NI 0.29 0.38 0.91 1.33 2.48
ZN 0.12 0.37 0.73 1.12 2.08
Iberian Sea CD -0.21 0.11 -0.03 0.81 0.97
CR
CU
PB 0.24 0.11 0.42 1.27 1.52
HG 0.01 0.11 0.19 1.01 1.21
ZN