Highly weathered soils are distributed in the humid and wet-dry tropics, as well as in the humid subtropics. As a result of strong weathering, these soils are characterized by low activity clays, which develop variabl...Highly weathered soils are distributed in the humid and wet-dry tropics, as well as in the humid subtropics. As a result of strong weathering, these soils are characterized by low activity clays, which develop variable surface charge and related specific properties. Surface reactions regarding base exchange and soil acidification, heavy metal sorption and mobility, and phosphorus sorption and availability of the tropical highly weathered soils are reviewed in this paper.Factors controlling surface reactivity towards cations and anions, including ion exchange and specific adsorption processes, are discussed with consideration on practical implications for rational management of these soils. Organic matter content and pH value are major basic factors that should be controlled through appropriate agricultural practices, in order to optimise favorable effects of colloid surface properties on soil fertility and environmental quality.展开更多
Variations of sea surface height （SSH） in the Kuroshio south of Japan are addressed by analyzing 19-year （1993-2011） altimetry data from AVISO. Regionally averaged time series of observed SSH had a rising linear t...Variations of sea surface height （SSH） in the Kuroshio south of Japan are addressed by analyzing 19-year （1993-2011） altimetry data from AVISO. Regionally averaged time series of observed SSH had a rising linear trend at 2.64＋0.72 mrn/a in this period. By analyzing the power spectra, several periods were recognized in temporal SSH variations, including those around 90 and 360 days. The seasonal cycle of SSH was minimum in winter （February） and maximum in summer （August）, with peak-to-peak amplitude about 20.0 cm. The spatial distribution of linear trends was inhomogeneous, with a rising linear trend along the coastline and a tripole structure offshore. Spatial distributions of standard deviation of seasonal SSH show very dynamic activities in the southeast of Kyushu and south of Honshu. Seasonal variations of observed SSH are partially explained by surface buoyancy forcing, local wind forcing and the steric component related to subsurface water beneath the mixed layer. Results show different spatial distributions of correlation coefficient and estimation skill between seasonally observed and modeled SSH, which are calculated from surface buoyancy flux, local wind forcing and the steric component related to subsurface water. Of those three, the surface buoyancy flux has a greater contribution to variations of observed SSH on the seasonal time scale south of Japan.展开更多
文摘Highly weathered soils are distributed in the humid and wet-dry tropics, as well as in the humid subtropics. As a result of strong weathering, these soils are characterized by low activity clays, which develop variable surface charge and related specific properties. Surface reactions regarding base exchange and soil acidification, heavy metal sorption and mobility, and phosphorus sorption and availability of the tropical highly weathered soils are reviewed in this paper.Factors controlling surface reactivity towards cations and anions, including ion exchange and specific adsorption processes, are discussed with consideration on practical implications for rational management of these soils. Organic matter content and pH value are major basic factors that should be controlled through appropriate agricultural practices, in order to optimise favorable effects of colloid surface properties on soil fertility and environmental quality.
基金Supported by the National Natural Science Foundation of China(No.41230420)the Basic Research Program of Science and Technology Projects of Qingdao(No.11-1-4-95-jch)the Knowledge Innovation Program of Chinese Academy of Sciences(No.KZCX2-EW-201)
文摘Variations of sea surface height （SSH） in the Kuroshio south of Japan are addressed by analyzing 19-year （1993-2011） altimetry data from AVISO. Regionally averaged time series of observed SSH had a rising linear trend at 2.64＋0.72 mrn/a in this period. By analyzing the power spectra, several periods were recognized in temporal SSH variations, including those around 90 and 360 days. The seasonal cycle of SSH was minimum in winter （February） and maximum in summer （August）, with peak-to-peak amplitude about 20.0 cm. The spatial distribution of linear trends was inhomogeneous, with a rising linear trend along the coastline and a tripole structure offshore. Spatial distributions of standard deviation of seasonal SSH show very dynamic activities in the southeast of Kyushu and south of Honshu. Seasonal variations of observed SSH are partially explained by surface buoyancy forcing, local wind forcing and the steric component related to subsurface water beneath the mixed layer. Results show different spatial distributions of correlation coefficient and estimation skill between seasonally observed and modeled SSH, which are calculated from surface buoyancy flux, local wind forcing and the steric component related to subsurface water. Of those three, the surface buoyancy flux has a greater contribution to variations of observed SSH on the seasonal time scale south of Japan.
