The variables in sediment_stations.csv describe the sediment monitoring stations used in the 2016 assessment of the UK's Clean Seas Environment Monitoring Programme and that underpin four of the indicator assessments in the UK's 2018 MSFD assessment of Descriptor 8.
The column Headings are:

biogeo_region
Description: biogeographic region
Discrete/Continuous/categorical: Categorical
Range or Levels: 8 levels
Notes: Biogeographic regions used for MSFD assessment purposes. (Charting Progress 2 regions)

CSEMP_region
Description: monitoring region
Discrete/Continuous/categorical: Categorical
Range or Levels: 19 levels
Notes: Monitoring regions for the UK’s Clean Seas Environmental Monitoring Programme (CSEMP); there are 22 regions in total (see map in separate PDF resource), but only 19 with data. The CSEMP regions are aggregated into 8 biogeographic regions for MSFD assessment purposes

stratum
Description: subdivision of monitoring region
Discrete/Continuous/categorical: Categorical
Range or Levels: 73 levels
Notes: Subdivisions of the CSEMP monitoring regions, most of which are WFD water bodies; there are 818 strata in total, but only 73 with data.

station
Description: station identifier
Discrete/Continuous/categorical: Categorical
Range or Levels: 101 levels

latitude
Description: station latitude
Units: Decimal Degrees
Discrete/Continuous/categorical: continuous
Range or Levels: 50.29 - 60.69
Notes: These are nominal positions: sampling occurs in a pre-defined area centred on this position.

longitude
Description: station longitude
Units: Decimal Degrees
Discrete/Continuous/categorical: continuous
Range or Levels: -8.58 - 2.33 (Negative = degrees west)
Notes: These are nominal positions: sampling occurs in a pre-defined area centred on this position.

MSTAT
Description: station type
Discrete/Continuous/categorical: Categorical
Range or Levels: B, RH, IH
Notes:
B = Baseline stations in remote areas subject only to diffuse inputs of contaminants
RH = Representative stations broadly representative of contaminant levels in the region
IH = Impacted stations located close to a point source

WLTYP
Description: stratum typography
Discrete/Continuous/categorical: Categorical
Range or Levels: Estuary, Coast, Open Sea
Notes:
Estuary = WFD transitional water
Coast = WFD coastal water
Open Sea = Marine water (stratum not covered by WFD)