This research was conducted at the sand dunes stabilization research s tation in Baiji district, Iraq. Three techniques for sand dunes stabilization ar e selected: the first method is stabilization by clayey block ba...This research was conducted at the sand dunes stabilization research s tation in Baiji district, Iraq. Three techniques for sand dunes stabilization ar e selected: the first method is stabilization by clayey block barriers; the seco nd method is stabilization by dry planting of tamarix (tamarix articulata) cutti ngs and the third is stabilization by using cane branch barriers. Randomized sam ples were taken from the surface and subsurface layers of the stabilized and shi fting sand dunes to evaluate the effect of the three techniques on wind erosion parameters. The results indicate high significant differences between the wind e rosion parameters in the surface and subsurface layers in the stabilized sand du nes, while there are insignificant differences between the subsurface layer of t he stabilized dunes and the surface and subsurface layers in the active sand dun es. The results clarify the fact that there is an increase in the percentage of clay, silt, organic matter, mean weight diameter and the percentage of the dry a ggregates (>0.84 mm). A decrease is found in the rate of disaggregation for the dry aggregates in the samples of the surface layer of stabilized dunes when comp ared with the subsurface layer of stabilized dunes and the surface layer of the shifting sand dunes. There is a positive high significant correlation among the aggregate stability parameters and the percentage of clay and silt, and the cont ent of organic matter in the studied layers.展开更多
Since 1988, the Japan Enoshima Aquarium (JEA) and the Institute of Hydrobiology of Chinese Academy of Sciences(IHCAS) have carried out long-term joint research on the conservation of Baiji dolphins (Lipotes vexillifer...Since 1988, the Japan Enoshima Aquarium (JEA) and the Institute of Hydrobiology of Chinese Academy of Sciences(IHCAS) have carried out long-term joint research on the conservation of Baiji dolphins (Lipotes vexillifer). According to the research, the population of Baiji dolphins has been decreasing rapidly from 300 in 1986 to less than 100 at present due to environmental deterioration of the Yangtze River. Since it is impossible to conserve the species in the river, as many as possible of the dolphins should be collected and transferred展开更多
文摘This research was conducted at the sand dunes stabilization research s tation in Baiji district, Iraq. Three techniques for sand dunes stabilization ar e selected: the first method is stabilization by clayey block barriers; the seco nd method is stabilization by dry planting of tamarix (tamarix articulata) cutti ngs and the third is stabilization by using cane branch barriers. Randomized sam ples were taken from the surface and subsurface layers of the stabilized and shi fting sand dunes to evaluate the effect of the three techniques on wind erosion parameters. The results indicate high significant differences between the wind e rosion parameters in the surface and subsurface layers in the stabilized sand du nes, while there are insignificant differences between the subsurface layer of t he stabilized dunes and the surface and subsurface layers in the active sand dun es. The results clarify the fact that there is an increase in the percentage of clay, silt, organic matter, mean weight diameter and the percentage of the dry a ggregates (>0.84 mm). A decrease is found in the rate of disaggregation for the dry aggregates in the samples of the surface layer of stabilized dunes when comp ared with the subsurface layer of stabilized dunes and the surface layer of the shifting sand dunes. There is a positive high significant correlation among the aggregate stability parameters and the percentage of clay and silt, and the cont ent of organic matter in the studied layers.
文摘Since 1988, the Japan Enoshima Aquarium (JEA) and the Institute of Hydrobiology of Chinese Academy of Sciences(IHCAS) have carried out long-term joint research on the conservation of Baiji dolphins (Lipotes vexillifer). According to the research, the population of Baiji dolphins has been decreasing rapidly from 300 in 1986 to less than 100 at present due to environmental deterioration of the Yangtze River. Since it is impossible to conserve the species in the river, as many as possible of the dolphins should be collected and transferred
