samples were collected from the study area including 8 sample
points as positioning data. Another 39 samples were collected from
farm lands of the study area. Simultaneously, 97 soil samples were
also collected from the study area to accomplish spatial coverage of
samples during April, 2014. Five topsoil samples were collected
within a 5m radius following a “S” sampling procedure (Liu et al.,
2013) and were bulked as a composite sample. The longitudes and
latitudes of the sampling points were recorded in a portable global
positioning system (GPS) receiver. All soil samples were air-dried
at room temperature for 7 days and then passed through 2mm
polyethylene sieve to remove stones or other debris. Portions of
soil samples (about 50 g) were ground and sieved through a
0.15mm mesh. Finally, the soil samples were quartered as subsamples
for further chemical analyses. The distribution of sample
locations in the study area is shown in Fig. 1.