Urban soils have been drastically disturbed and modified by human activities. Soil sealing, necessary for transportation and infrastructure development, is one such process, which often results in negative effects on the soil ecosystem functions. However, sealed soils can play a critical role in material cycling through ground surfaces in urban ecosystems. This study investigated the effects of asphalt sealing on the mineral soils beneath the roads in Tokyo. The results confirmed that mineral soils beneath asphalt pavements were characterized by high pH levels, CaO content, inorganic carbon (IC), and electric conductivity (EC) due to liming for road material fixation at the subbase layers. An analysis of the concentrations of IC and Ca, or pH value suggested existence of calcium carbonate (CaCO 3 ) mainly due to liming and absorption of atmospheric CO 2 at subbase layers. Relatively high content of sulfur in the subbase layers is likely attributed to asphalt contaminants originating from petroleum. Removal of the original surface soils, for new road development, decreased oxides and organic matter content. Contents of oxides in top mineral soils were low as compared to those of natural Andosols by mixing of subbase materials. This study suggested that construction of asphalt pavement induced specific soil genesis beneath asphalt pavement such as soil alkalinization, calcium carbonate accumulation, and technogenic material mixing. First, surface soil removal for the construction of asphalt pavement decreases organic matter content in mineral soils. Concurrently technogenic materials mix with top mineral soils. Second, Ca dissolved into water from the subbase layer can react with dissolved inorganic carbon followed by calcium carbonate formation and Ca cation migration into the deeper horizon. As asphalt pavement intercepts litter supply, organic matter accumulation was prevented in mineral soils beneath the asphalt pavement. Our study confirmed that owing to the water infiltration, through pervious asphalt and the cracks developed on the asphalt surface by heavy traffic, material cycling exists even in mineral soils beneath the asphalt pavements.
We measured the spin-lattice relaxation times (T1) of water protons and intermolecular cross-relaxation times (T(IS)) from irradiated protein protons (f2-irradiation at 1.95 or -4.00 ppm) of rabbit normal and monoiodoacetate-induced degenerated knee articular cartilages to observed water protons. The mean values of T1 (T1) for control and degenerated rabbit knee cartilages were 1.87+/-0.15 (mean+/-SD, n=29) and 1.82+/-0.13 s (n=34), respectively. The mean values of water content (W(H2O)) for control and degenerated rabbit knee cartilages were 82.9+/-2.09 (n=26) and 83.1+/-2.57% (n=28), respectively. These values were not statistically different from each other. However, the mean values of T(IS) (T(IS)) for normal knee articular cartilage were significantly different from those for degenerated cartilage: (normal), T(IS) (f2=1.95 ppm)=2.46+/-0.62 s (n=28), T(IS) (f2=-4.00 ppm)=4.25+/-1.26 s (n=26); (degenerated), T(IS) (f2=1.95 ppm)=1.99+/-0.76s (n=34), T(IS) (f2=-4.00 ppm)=3.33+/-0.76 s (n=31). Obtained results may be attributed to the reported switchover from type II to type I collagen syntheses in osteoarthritic cartilage, resulting in broad collagen fibers. This specificity of cross-relaxation effect may prove useful in the noninvasive and pathophysiological evaluation of cartilage tissues in vivo.
To identify the soil carbon stock change from cropland to forest land in Japan, we compared the soil carbon stock of a cropland and that of an adjacent forest land at 23 different sites. With regard to a 0-30 cm depth basis, the soil carbon stock in the cropland was greater than that in the forest land; however, it was less than that in the forest land when an equivalent mass basis was used. In less than an elapsed time of 20 years after a land-use change, the soil carbon stock after afforestation was less than that in the adjacent cropland at the same sites. However, after an elapsed time of 20 years, the soil carbon stock in the afforested site exceeded that in the adjacent cropland at the same sites. The ratio of the soil carbon stock in forest land to that in the cropland was 1.10 on average, which is comparable with the previous mass-corrected paired-sampling studies. The ratio in the conifer-planted forest was significantly greater than that in the hardwood re-generated forest. Some of the previous reviews, including those of the non-mass-corrected data, were possibly biased, and more studies using the paired-sampling method with equivalent mass basis need to provide more general ratios in the future.
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