This situation could suggest that deposition had occurred at
these 22 points during the period 1998e2013. However, this is
thought to be unlikely, due to the lack of visual evidence of deposition
on the slopes of the study catchment and the absence of
deposition at any of the 55 points sampled in 1998. It is therefore
seen as emphasising that the points sampled in 2013 did not
replicate exactly the points sampled in 1998. As indicated above,
the points sampled in 2013 were located close to those sampled in
1998, but were positioned ca. 2 m away in order to avoid the area
disturbed by sampling undertaken during the original survey. The
pattern evident in Fig. 3 is seen as reflecting the small-scale variability
of inventories in uncultivated soils (cf. Owens and Walling,
1996), which reflects the heterogeneity of such soils in the
absence of tillage. Sutherland (1996) has reported that individual
cores collected in close proximity from reference sites located
within undisturbed forested areas are typically characterised by a
coefficient of variation of ca.19e47%. This situation precludes direct
comparison of the 137Cs inventories obtained for individual points
in this study catchment by the two sampling campaigns. Following
the approach used by Loughran and Balog (2006), the two sets of
samples and their associated estimates of soil redistribution rate
have been treated as independent sets of representative samples
collected from the study catchment on two separate occasions.
This situation could suggest that deposition had occurred atthese 22 points during the period 1998e2013. However, this isthought to be unlikely, due to the lack of visual evidence of depositionon the slopes of the study catchment and the absence ofdeposition at any of the 55 points sampled in 1998. It is thereforeseen as emphasising that the points sampled in 2013 did notreplicate exactly the points sampled in 1998. As indicated above,the points sampled in 2013 were located close to those sampled in1998, but were positioned ca. 2 m away in order to avoid the areadisturbed by sampling undertaken during the original survey. Thepattern evident in Fig. 3 is seen as reflecting the small-scale variabilityof inventories in uncultivated soils (cf. Owens and Walling,1996), which reflects the heterogeneity of such soils in theabsence of tillage. Sutherland (1996) has reported that individualcores collected in close proximity from reference sites locatedwithin undisturbed forested areas are typically characterised by acoefficient of variation of ca.19e47%. This situation precludes directcomparison of the 137Cs inventories obtained for individual pointsin this study catchment by the two sampling campaigns. Followingthe approach used by Loughran and Balog (2006), the two sets ofsamples and their associated estimates of soil redistribution ratehave been treated as independent sets of representative samplescollected from the study catchment on two separate occasions.
การแปล กรุณารอสักครู่..
