This contribution analyzes the similarities and differences between the measured activities of 137Cs and excess 210Pb(210Pbex) in the cultivated brown and cinnamon soils of the Yimeng Mountain area, discusses the influence of soil texture on the measurement of 210Pbex, and presents differences between the two types of soils. Fields A and B were selected to represent the fields that contain cultivated brown and cinnamon soils, respectively. From either study field, one site of sectioned core and six bulk cores were collected to measure 137Cs levels, 210Pbex levels, and the particle-size composition of soil samples. Three undisturbed soil samples were collected to measure capillary and aeration porosities. The 137Cs inventories for the two study fields are very similar. The 137Cs is a man-made radionuclide, which means that its measured levels for soils are unaffected by soil texture. In contrast, levels of the naturally occurring 210Pbex of soils from Field A were lower than those of Field B by about 50%. In contrast to aquatic sediments, levels of 210Pbex in terrestrial surface soils are affected by the emanation of 222Rn from the soils. It can be assumed that the coarser the soils, the greater the emanation of 222Rn; in addition, the lower the measured 210Pbex, the greater the underestimate of this value. The cultivated brown soils in Field A are coarser than the cultivated cinnamon soils in Field B. As a result, 222Rn in Field A will diffuse more easily into the atmosphere than that in Field B. As a consequence, the measured 210Pbex in soils from Field A is much lower than the actual value, whereas the value measured for Field B is much closer to the actual value.
The thermal effect of urban impervious surfaces （UIS） is a complex problem. It is thus necessary to study the relationship between UIS and land surface temperatures （LST） using complexity science theory and methods. This paper investigates the long-range cross- correlation between UIS and LST with detrended cross- correlation analysis and multifractal detrended cross- correlation analysis, utilizing data from downtown Shanghai, China. UIS estimates were obtained from linear spectral mixture analysis, and LST was retrieved through application of the mono-window algorithm, using Landsat Thematic Mapper and Enhanced Thematic Mapper Plus data for 1997-2010. These results highlight a positive long-range cross-correlation between UIS and LST across People＇s Square in Shanghai. LST has a long memory for a certain spatial range of UIS values, such that a large increment in UIS is likely to be followed by a large increment in LST. While the multifractal long-range cross- correlation between UIS and LST was observed over a longer time period in the W-E direction （2002-2010） than in the N-S （2007-2010）, these observed correlations show a weakening during the study period as urbanization increased.
The existing^(210)Pb_(ex)mass balance models for the assessment of cultivated soil erosion are based on an assumption that^(210)Pb_(ex)is quite evenly mixed within the plough layer.However,the amount of^(210)Pb_(ex)distributed in the soils below the plough depth,like a downward tail in the lower part of the^(210)Pb_(ex)profile,has been largely ignored.In fact,after the initial cultivation of undisturbed soils,^(210)Pb_(ex)will diffuse downward from plough layer to the plough pan layer due to the concentration gradient.Assuming^(210)Pb_(ex)inventory is constant,the depth distribution in the two layers of the cultivated soils will achieve a steady state after continuous cultivation for 10.37 years,when^(210)Pb_(ex)is evenly distributed in the soils of the plough layer with an exponential concentration decline with depth in the soils of the plough pan layer,and the^(210)Pb_(ex)concentration at any depth will be invariable with time.The work reported in this paper attempts to explain the formation of the^(210)Pb_(ex)tail in the soil profile below the plough depth by theoretical derivation of the^(210)Pb_(ex)depth distribution process in the two layers of the cultivated soils,propose a^(210)Pb_(ex)mass balance model considering^(210)Pb_(ex)diffusion based on the existing model,and discuss the influence of the^(210)Pb_(ex)tail to the existing model.
