DIGITALNA ARHIVA ŠUMARSKOG LISTA
prilagođeno pretraživanje po punom tekstu
| ŠUMARSKI LIST 7-8/2021 str. 28 <-- 28 --> PDF |
2) There was no statistically significant difference between series from the same sampling year, and from different heights, which can be interpreted as a homogeneous height distribution of 137Cs activity in the twenty youngest years of the tree rings. Distribution of 137Cs in bark and cambium of silver fir – Distribucija 137Cs u kori i kambiju obične jele In Figure 9, (comparing only the same tissue type in the same year) a general increase of 137Cs activity in the bark and cambium can be found correlating with the tree height (except at 0.1 m in 2003). In 2003, the highest concentration of 137Cs was measured in bark samples collected at a tree height of 16 meters, measuring 130.1 ± 1.5 Bq/kg, while the value of the measured sample at the same height in 2004 was 50.7 ± 1.2 Bq/kg. At the same height (16 m), the 137Cs activity in cambium was 124.1 ± 1.4 Bq/kg measured in 2003, and in 2004 it was 79.2 ± 1.6 Bq/kg. In the samples of the bark on tree height of 8 meters in 2003 measured 137Cs activity was 83.8 ± 1.4 Bq/kg, and in 2004 was 38.7 ± 1.0 Bq/kg. At the same height (8 m) in 2003 measured 137Cs activity in the cambium was 77.6 ± 1.4 Bq/kg, and in 2004 it was 65.2 ± 1.4 Bq/kg. At a height of 0.1 m, the measured 137Cs activity in the bark sample of 2003 was 70.6 ± 1.3 Bq/kg, and in 2004 sample it was 24.0 ± 0.3 Bq/kg. At the same height (0.1 m), the 137Cs activity in the cambium was 80.5 ± 1.5 Bq/kg measured in 2003, and in 2004 it was 27.0 ± 0.3 Bq/kg. The values of the measured 137Cs activity in 2017 and recalculated to day July 1, 2003 amounted to 13.8 ± 2.0 Bq/kg in bark and to 18.4 ± 2.67 Bq/kg, in cambium, recalculated to day July 1, 2016 amounted 10.2 ± 1.48 Bq/kg in bark and 13.6 ± 1.3 Bq/kg in cambium. Distribution of 137Cs in the root of the silver fir – Distribucija 137Cs u korijenu obične jele Distribution of 137Cs activity in the root thickness classes of silver fir of 2003 and 2004 samples is shown in Figure 10. The samples from the 2003 showed of 137Cs activity variation ranging from 62.1 ± 1.3 Bq/kg (root thickness 1-2 mm) to 98.4 ± 1.8 Bq/kg, while in samples from 2004, the range was from 31.4 ± 1.0 Bq/kg (root thickness 3-4 mm) to 71.2 ± 2.3 Bq/kg (tiniest roots). Meanwhile, the value nearest the maximum (recorded in the thinnest roots) for both years were recorded in the thickest roots (25-38 mm; 95.5 ± 2.7 Bq/kg in samples from 2003; 44.9 ± 1.5 Bq/kg in samples from 2004) which at the qualitative level indicate the absence of a link between root thickness and 137Cs activity. This conclusion is supported by the analysis of the association of 137Cs activity with the upper limit of the root thickness class, performed by the Spearman-rank correlation method, suitable for small samples, which did not result in a significant correlation (RSP = 0.1429 with p = 0.7599 for 2003). RSP = - 0.3214 with p = 0.4821 for 2004). Accordingly, it can be concluded that no significant variability in 137Cs activity has been observed in the fir root system, which could be due to the fact that these are plant tissues that overgrow the soil from which the tree draws 137Cs. By comparing the values of two sampling years separately for each diameter class roots (Figure 10), we can see that in 2003 (winter period) each diameter class recorded higher values than in 2004 (growing season). This result could be explained by the assumption that in winter, because of slower metabolism and less intensive flow through the vascular tissue of roots, roots temporarily accumulate 137Cs, whose |