中文摘要：

锰是土壤中的一种重要元素,其迁移过程可在一定程度上反映水土流失过程。为进一步阐明小流域内水土流失过程和小流域土壤有效锰的分布特征,采用DTPA-原子吸收火焰分光光度法对鹦鹉沟小流域不同地形因子、土地利用方式下土壤有效锰质量分数的测定,作出流域内土壤有效锰质量分数的各个方向分形维数,得出该小流域有效态锰的分布特征。结果表明：鹦鹉沟小流域土壤有效锰质量分数范围为7.43-57.67 mg/kg,均值为39.52mg/kg;海拔480-540 m地区质量分数最高,为41.61 mg/kg,变异系数从大到小为低海拔、中海拔、高海拔;8-14°坡度质量分数分布最高,为43.32 mg/kg,在不同坡度上变异系数从大到小为：较缓坡、微坡、急陡坡、较陡坡、缓坡;上坡位质量分数最高42.16 mg/kg,变异系数从大到小上坡位、中坡位、下坡位;林地质量分数最高42.07 mg/kg,变异系数从大到小为农地、林地、草地;在45°方向上具有较显著的分形特征,且变异程度最高。

英文摘要：

Manganese（ Mn） is one of important elements in soil and its transportation process is an reflection of soil and water loss. In order to understand more deeply about the process of soil and water loss,the content of available Mn in Yingwugou watershed located in Shaanxi Province was investigated.This study employed DTPA-atomic absorption fire spectrophotometry to measure the content of available Mn in different topography and land use types of the watershed. Then fractal dimension of the content of available Mn in a few directions was calculated and finally the distribution of the content of available Mn was clarified. The results showed that the content of soil available Mn at the Yingwugou watershed ranged from 7. 43-57. 67 mg / kg,39. 52 mg / kg on average. 1） Middle elevation had the highest content（ 41. 61 mg / kg） and the value of the coefficient variation（ CV） from high to low was ordered distinctively as low,middle,and high,suggesting that the available Mn in soil is moved from high to low elevations by runoff in the watershed after leaching,gathers at middle or low elevation areas,and finally the available Mn atlow elevation areas is carried away by flowing river. The highest content of available Mn（ 43. 32 mg / kg）could be found on slopes with degree ranging from 8-14° and the value of CV from high to low was ranked as very gentle slope,micro-slope,very steep slope,steep slope and gentle slope; the available Mn was easier to aggregate at very gentle slope,micro-slope,and steep slope. The upslope position had the highest content（ 42. 16 mg / kg） and the value of CV from high to low was ordered as down slope,middle slope,upslope,indicating that runoff is the main force to move the available Mn. 2） The woodland had the highest content of 42. 07 mg / kg and the value of CV from high to low was ranked as farmland,woodland,grassland. The woodland and the grassland had more complicated soil structures because of more biocenoses and less disturbance. The grass roots have a high ability t