The variables in sediment_data.csv describe the contaminant data in sediment used to construct the National Performance Framework Clean Seas Indicator 2018. The data are also used to make regional assessments of status and trends in Scottish waters for selected contaminant groups in sediment. The column headers are:

seriesID
Description: timeseries identifier
Unit:
Type: categorical
Levels: 1248
Note: identifies the data (a station / contaminant combination) that were grouped together into a timeseries and modelled to assess status and trends

station
Description: station identifier
Unit:
Type: categorical
Levels: 52
Note: monitoring station – links to station information in sediment_stations.csv

year
Description: monitoring year
Unit:
Type: discrete
Range: 1999, 2017
Note: for some data suppliers, monitoring is in winter and e.g. sampling in December 2016 and January 2017 would be regarded as having come from the same monitoring year

date
Description: sampling date
Unit:
Type: discrete
Range: 1999-01-18, 2017-01-16
Note:

sampleID
Description: sample identifier
Unit:
Type: categorical
Levels: 1918
Note:

matrix
Description: sample matrix
Unit:
Type: categorical
Levels: SED63, SEDTOT
Note: see ICES reference codes for MATRX

group
Description: contaminant group
Unit:
Type: categorical
Levels: BDE, CB, metal, PAH.parent
Note:
BDE = polybrominated diphenyl ethers
CB = polychlorinated biphenyls
PAH.parent = parent polycyclic aromatic hydrocarbons

determinand
Description: contaminant
Unit:
Type: categorical
Levels: 26
Note: see ICES reference codes for PARAM; data submitted as CHRTR have been relabelled as CHR

metoa
Description: method of chemical analysis
Unit:
Type: categorical
Levels: 11
Note: see ICES reference codes for METOA

concentration
Description: concentration of contaminant
Unit: mg/kg dw (metals), ug/kg dw (organics)
Type: continuous
Range: 0.0015, 4080
Note: all contaminant concentrations are expressed on a dry weight basis

qflag
Description: less-than qualifier for the concentration measurement
Unit:
Type: categorical
Levels: "", "<"
Note:
“<” indicates a value below the limit of detection
"” indicates a value above the limit of detection

uncertainty
Description: uncertainty in the concentration measurement
Unit: as for concentration
Type: continuous
Range: 0.0000075, 639
Note: analytical uncertainty expressed as the standard deviation

normConc
Description: normalised concentration of contaminant
Unit: as for concentration
Type: continuous
Range: 0.0082, 4887
Note: the concentration normalised to 5% aluminium (metals) or 2.5% organic carbon (organics); the normalisation process is explained here; some normalised concentrations are ‘missing’ because the normaliser (aluminium or organic carbon) concentration was not reported or because the uncertainty in the normalised concentration was greater than the normalised concentration

normConc.qflag
Description: less-than qualifier for the normalised measurement
Unit:
Type: categorical
Levels: "", "<"
Note: see qflag

normConc.uncertainty
Description: uncertainty in the normalised measurement
Unit: as for concentration
Type: continuous
Range: 0.00075, 887
Note: analytical uncertainty expressed as the standard deviation

AL
Description: aluminium concentration
Unit: %
Type: continuous
Range: 0.087, 48.2
Note: all values are above the limit of detection

AL.uncertainty
Description: uncertainty in the aluminium measurement
Unit: %
Type: continuous
Range: 0.014, 3.06
Note: analytical uncertainty expressed as the standard deviation

CORG
Description: organic carbon concentration
Unit: %
Type: continuous
Range: 0.03, 8.7
Note:

CORG.qflag
Description: less-than qualifier for the organic carbon measurement
Unit:
Type: categorical
Levels: "", "<"
Note: see qflag

CORG.uncertainty
Description: uncertainty in the organic carbon measurement
Unit: %
Type: continuous
Range: 0.008, 2.86
Note: analytical uncertainty expressed as the standard deviation

DRYWT
Description: dry weight of the sample
Unit: %
Type: continuous
Range: 8.33, 94.8
Note: all values are above the limit of detection

DRYWT.uncertainty
Description: uncertainty in the dry weight measurement
Unit: %
Type: continuous
Range: 0.29, 3.35
Note: analytical uncertainty expressed as the standard deviation