|
B otter length |
total length, nose to tip
of tail (mm). Included to control for differences in concentration
as a result of body size. Correlated with sex due to sexual dimorphism |
measured at post-mortem
examination by Cardiff University Otter Project (CUOP) |
all |
|
B otter sex |
male (n = 27)
or female (n = 23). Differences between male
and female may include offloading of pollutants to offspring for females |
determined at post-mortem
examination by CUOP |
none, due to collinearity
with length |
|
B otter body
condition |
scaled
mass index (SMI)
estimate of body condition (using Peig and Green34). Test for the potential impact of PFASs on body condition
or vice versa |
calculated
from length and
weight measurements taken during post-mortem examination by CUOP |
all |
|
S percentage
landfill area |
percentage
of land in 10
km buffer of otter that has historic or currently used landfill sites.
Source of PFASs via the disposal of consumer products |
Natural Resources Wales47,48 and Environment Agency49,50
|
all |
|
S percentage
urban area |
percentage
of urban and
suburban land in the 10 km radius of otter. Source of PFASs via the
use of consumer products, and the use of PFAS-based firefighting foam,
including at airports |
U.K. Centre for Ecology
and Hydrology—Land Cover Map 200751
|
none, due to collinearity
with proportion landfill area |
|
S mean wastewater
treatment works load |
mean load entering WWTW,
measured in population equivalent (PE), within a 10 km radius around
each otter. Source of PFASs via the disposal of industrial and domestic
wastewater |
European
Environment Agency52
|
all |
|
S percentage
pastoral land |
percentage
of improved grassland
within a 10 km radius around each otter. Potential proxy for the application
of sewage sludge on pastoral land |
U.K. Centre for Ecology
and Hydrology—Land Cover Map 200751
|
all |
|
S percentage
arable land |
percentage
of arable land
within the 10 km radius around each otter. Potential proxy for the
application of sewage sludge on arable land |
U.K. Centre for Ecology
and Hydrology—Land Cover Map 200751
|
all |
|
S rainfall |
mean rainfall (mm) within
the 10 km radius around each otter from years 2006–2009. Source
of PFASs via atmospheric deposition or dilution within river |
Met Office53
|
none,
due to collinearity
with proportion arable land |
|
S distance to
factory producing PTFE |
linear distance from each
otter to a factory using PFOA at a time of sampling (2007–09)
in PTFE manufacture (AGC Chemicals Europe Ltd, Lancashire) |
calculated using ArcGIS
join tool to factory location54
|
PFOA only |
|
S PFOS discharge
to water |
binary variable,
discharge
reported, or no discharge reported within a 10 km radius around each
otter |
pollution inventories
for
Wales and England55,56
|
PFOS only |
