A new immunoassay was developed to detect denaturation of type II collagen in osteoarthritis (OA). A peptide, al(II)-CBllB, located in the CB11 peptide of type II collagen, was synthesized and used to produce a monoclonal antibody (COL2-3/4m) of the IgG,(K) isotype. This reacts with a defined epitope in denatured but not native type II collagen and the a3 chain of type XI collagen. The latter is present in very small amounts (about 1% wt/wt) in cartilage relative to the al (II) chain. By using an enzyme-linked immunosorbent assay, type II collagen denaturation and total type II collagen content were determined. The epitope recognized by the antibody was resistant to cleavage by a-chymotrypsin and proteinase K which were used to extract al (II)-CB11B from the denatured (a-chymotrypsin soluble) and residual native (proteinase K soluble) collagen a-chains, respectively, present in human femoral articular cartilage. Type II collagen content was significantly reduced from a mean (range) of 14% (9.2-20.8%) of wet weight in 8 normal cartilages to 10.3% (7.4-15.0%) in 16 OA cartilages. This decrease, which may result in part from an increased hydration, was accompanied by an increase in the percent denaturation of type II collagen in OA to 6.0% of total type II collagen compared with 1.1% in normal tissue. The percent denaturation was ordinarily greater in the more superficial zone than in the deep zone of OA cartilage. (J. Clin. Invest.

[1] A dramatic reduction in soil frost depth has been reported for Hokkaido Island of northern Japan over the last 20 years. Since soil frost strongly affects snowmelt infiltration and runoff, the reduction in frost depth may have altered the water and nutrient cycles in this region. A paired-plot experiment was conducted in an agricultural field in Tokachi, Hokkaido, to compare the movement of soil water at different frost depths, controlled by manipulating the depth of snow cover. Snow was removed to enhance soil freezing in the treatment plot and was undisturbed in the control plot. The soil froze to a maximum depth of 0.43 m under the treatment plot and 0.11 m under the control plot. During the freezing period, the amount of upward soil water flux toward the freezing front in the treatment plot was more than double that in the control plot. During the snowmelt period, infiltration of meltwater was unimpeded by the thin frozen layer in the control plot, whereas the relatively thick frozen layer in the treatment plot impeded infiltration and generated 63 mm of runoff. These results clearly show that the changes in the timing and thickness of snow cover deposition can cause a dramatic reduction of frost depth and change in the soil water dynamics.Citation: Iwata, Y., M. Hayashi, S. Suzuki, T. Hirota, and S. Hasegawa (2010), Effects of snow cover on soil freezing, water movement, and snowmelt infiltration: A paired plot experiment, Water Resour. Res., 46, W09504,

means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. ABBREVIATIONS: SWE, snow water equivalent; WCR, water content refl ectometer. ORIGINAL RESEARCHTh e depth of soil frost is decreasing in cold regions around the world as a result of climate warming. To evaluate the potential impacts of the reduction in frost depth on the hydrologic cycle, it is necessary to understand snowmelt infi ltration processes in frozen soils. A fi eld study was conducted at an agricultural site characterized by volcanic ash soil in Tokachi, Hokkaido, Japan, where frost depths have decreased signifi cantly in the last 20 yr. Soil temperature, water content, matric potential, snow cover, and meteorological parameters were monitored to quantify snowmelt infi ltration fl ux for four winters that had diff erent snow and soil conditions. When snowmelt began, the soil frost was 0.1 to 0.2 m thick in two winters and was absent in two other winters, providing a unique opportunity to compare snowmelt infi ltration under frozen and unfrozen conditions. Most of the snowmelt water infi ltrated into the soil under both frozen and unfrozen conditions, indicating that the frozen soil layer did not impede infi ltration. Th e lack of fl ow impedance in the frozen soil was partly due to relatively high air temperature and an absence of freeze-back events during the snowmelt period. Furthermore, the temperature of the frozen soil layer was close to 0°C when the melt started, meaning that very little meltwater refroze in the soil before the temperature reached 0°C. Th e thick (>1 m) snow cover insulated the soil surface, allowing the frozen soil layer to warm up with the upward conduction of heat from the unfrozen layer below. Th ese results indicate the importance of the interaction between snow cover and soil, which can be signifi cantly aff ected by climate change.

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Frozen ground plays an important role in the energy and water cycle of cold regions, and affects the environment and agricultural practices in these regions. The effect of climate warming on soil frost is an important concern, but our present understanding of such effect is limited, due to the lack of long-term data covering a large region. This study analyzes a unique regional database of 20-year records from 1986-2005 of soil frost, combined with long-term climate data from 1955-2005. Annual maximum frost depths ðD max Þ in the Township of Memuro (514 km 2 ) in Tokachi, Hokkaido have decreased significantly in the last 20 years. The decrease in D max was caused by the development of thick snow cover in early winter that insulates the ground, not by the increase in air temperature. The D max is strongly correlated with a soil freezing index ðF 20 Þ, that integrates the combined effects of air temperature and snow cover. Using F 20 as a surrogate of D max , it was shown that the decreasing frost depth was a regional phenomenon occurring over the Tokachi Plain, covering an area of several thousand square kilometers. The timing of a major decrease in F 20 in the mid to late 1980's coincided with sharp decreases of snowfall in the Hokuriku region of Japan and the amount of drift ice in the southern part of the Sea of Okhotsk, both of which are regarded as indicators of the strength of the East Asian winter monsoon activities.

No abstract

Snow surfaces have unique energy-exchange characteristics, which need to be correctly represented in hydrological and climate models. An intensive field study was conducted in an open farm field in Tokachi, Hokkaido, Japan in which all energy exchange fluxes were monitored during the snowmelt period in 2004. Energy inputs to the snow surface was dominated by net radiation, which provided 75% of total input, while sensible heat contributed significant input on days with strong wind. Snowmelt consumed 80% of energy and evaporation consumed 20%. Sensible and latent heat had similar magnitude but opposite direction, meaning that sensible heat input was nearly cancelled by latent heat loss (i.e., evaporation). Therefore, the snowmelt rate was strongly controlled by net radiation. Compared to previous studies in northern Japan, very high daily evaporation rates, up to 2.2 mm d À1 , were observed during episodic events. High evaporation was caused by the foehn (Tokachi-kaze), characterized by warm, dry, north-westerly wind descending the eastern slope of the mountains. The foehn events were associated with major extratropical cyclones over the sea east, or northeast of Hokkaido. Historical analysis of daily climate data showed that similar high-evaporation events associated with the foehn are common in Tokachi, although the magnitude of the event in 2004 was exceptional. Estimated evaporation rates during the melt periods in 1997-2004 had an average of 0.24 mm d À1 , indicating that evaporation plays a relatively minor role in the overall water balance of the snowpack. However, latent heat flux plays a significant role in energy balance.

Physicochemical properties of biochar, which are used as a soil amendment material in agricultural fields, are different depending on biomass feedstock and pyrolysis processes. In this study, we evaluated the influence of feedstock type and pyrolysis temperature on the water-retention related properties of biochar. Wood-chips [cedar (CE) and cypress (CY)]; moso bamboo (MB); rice husk (RH); sugarcane bagasse (SB); poultry manure (PM) and agricultural wastewater sludge (WS) were each pyrolysed at 400, 600 and 800 °C with a retention time of two hours. Scanning electron microscopy micrographs (SEM), hydrophobicity indices, pore-size distribution measured by mercury-intrusion porosimetry, water-retention curves (WRCs) and plant-available water capacities (AWCs) of the biochars were measured to evaluate their potentials as soil-amendment materials for improving soils’ water-retention. As the pyrolysis temperature was increased, the hydrophobicity index decreased. On the other hand, pyrolysis temperature did not affect the distribution of micrometre-range pores, which are useful for plant-available water, of biochars. The AWCs of the biochars formed from CE, CY and SB were greater than those produced from other feedstocks, at 600 and 800 °C. Therefore, we can suggest that the biochars derived from wood-chips (CE and CY) and SB have greater potential for enhancing soils’ water-retention.