## 3 Results
### Activity Concentrations and Correlation of Radionuclides
It is also possible that these nuclides respond similarly to the soil's geochemical behavior and to other environmental processes, as they are commonly distributed in the environment [10; 14; 30]. Some studies indicate positive correlations among the nuclides \({}^{226}\)Ra, \({}^{232}\)Th, and \({}^{40}\)K at each concentration [10; 14; 23; 30]. The activity concentrations ranged from 77.2 Bq/kg to 517.7 Bq/kg for \({}^{40}\)K, 3.9 Bq/kg to 31.6 Bq/kg for \({}^{226}\)Ra, and 5.3 Bq/kg to 39.1 Bq/kg for \({}^{232}\)Th. The mean and standard deviation values were 344.4 \(\pm\) 116.1 Bq/kg, 18.6 \(\pm\) 5.5 Bq/kg, and 26.5 \(\pm\) 8.4 Bq/kg for \({}^{40}\)K, \({}^{226}\)Ra, and \({}^{232}\)Th, respectively. The activity concentrations of the radionuclides in the present study were lower than the world soil average activity concentrations of 420 Bq/kg, 32 Bq/kg, and 45 Bq/kg for \({}^{40}\)K, \({}^{226}\)Ra, and \({}^{232}\)Th, respectively [14]. In these soil samples, \({}^{40}\)K had significantly higher activity concentrations than \({}^{232}\)Th and \({}^{226}\)Ra, while \({}^{232}\)Th had significantly higher activity concentrations than \({}^{226}\)Ra (\(p<\) 0.001). The abundance of potassium in the earth's crust [7; 31] means that \({}^{40}\)K was responsible for the majority (82.2-90.4%) of the activity concentrations found in the soil samples [1; 11; 18; 29; 32]. The levels of \({}^{232}\)Th and \({}^{226}\)Ra in the soil are impacted by the minerals present [1; 3; 7; 32]. Some soil samples may have higher concentrations of \({}^{232}\)Th, while others may have higher concentrations of \({}^{226}\)Ra [4; 18; 33; 34]. The levels of activity in the soil samples S14 and S15 were notably lower than those in the other samples. These two soil samples were collected near the coastline of the Bashi Channel, and their composition may be similar to that of the beach sand surrounding the Maanshan NPP, as shown in Figure 1. The beach sand is made up of debris from shells and coral reefs, resulting in significantly lower activity levels than soil. The white beach sands contain predominantly a mix of coral reef, shell, and light minerals, hence natural nuclides have low activity concentrations. Activity concentrations ranging from 10.7 Bq/kg to 58.3 Bq/kg, from 2.7 Bq/kg to 7.1 Bq/kg, and from 2.8 Bq/kg to 11.0 Bq/kg for \({}^{40}\)K, \({}^{226}\)Ra, and \({}^{232}\)Th, respectively, have been found in beach sands [35; 36; 37]. When mixed with soil, the sand causes a considerable decrease in activity levels. Soil activity concentrations vary across the world and are affected by factors such as mineral composition, particle size, geological conditions, and environmental processes specific to each region [5; 38; 39; 40]. The size of soil particles in the samples varied extensively, as presented in Table 1. The average percentage of clay was 35.0 \(\pm\) 14.5%, with a coefficient of variation (CV) of 41%. On the other hand, the mean percentage of sand was 47.4 \(\pm\) 18.7%, with a CV of 39%. The sampled area was situated in the Maanshan Formation, which comprises sedimentary layers ranging from the Pliocene to the Pleistocene. These layers consist of limestone clasts, blue-gray shale, and gray sandstone, all of which  
Figure 2: Linear correlation of the activity concentrations of \({}^{232}\)Th with \({}^{226}\)Ra and \({}^{228}\)Ra (**a**) and of \({}^{40}\)K with \({}^{232}\)Th and \({}^{226}\)Ra (**b**) in the soil samples. contain diverse fossils such as shellfish and foraminifera [10]. The sedimentary soil found in this area has low concentrations of natural radionuclides [7,11]. Maanshan NPP nears the coastline of the Bashi Channel, and the sampling area is relatively small, covering less than 10 km\({}^{2}\). Based on the variance in radioactivity, the sample seemed to contain a mix of soil, debris from shellfish, and foraminifera. [PERSON] et al. [11] measured the radioactivity of soils near nuclear power plants and storage facilities in Taiwan.