【摘要】 为揭示三峡水库首次蓄水至175 m后,干流柱状沉积物磷的蓄积特征及其影响因素,于2010年10月下旬采集了三峡水库干流云阳至秭归等5个断面柱状沉积物样品,分析了沉积物粒径、有机质、矿物成分、总磷等理化特征,采用分级提取法分析了柱状沉积物各形态磷分布特征,并对三峡水库柱状沉积物磷的释放贡献率进行估算.结果表明,三峡水库干流柱状沉积物p H在7. 3～7. 8间,总体呈中性.沉积物组成以粉砂为主,含量为49. 4%～78. 6%,黏土为20. 6%～50. 6%,含砂量低于4. 4%,各断面中值粒径沿深度呈现出阶段性地增加或降低趋势.沉积物有机质含量为12. 94～53. 43 g·kg^-1,从云阳至秭归断面沉积物有机质含量略有增加,碳氮比在4. 00～11. 64之间.三峡水库沉积物总磷为861. 86～1 024. 54 mg·kg^-1,同一断面沉积物总磷垂向变化较小,且没有随深度变化呈现规律性变化趋势.三峡沉积物磷形态以钙磷为主,约占总磷含量的47. 83%～73. 90%,其余各形态磷所占比例较小.不同断面间磷形态垂向变化趋势差异较大.可交换态磷、铝磷及铁磷在个别断面表层0～4 cm范围内含量相对较高,而在16～20 cm处大部分断面沉积物各形态磷均不随深度发生变化.在同一深度下,不同断面生物可利用磷（可交换态磷、铁磷、铝磷之和,Bio-P）的含量及相对含量沿程分布趋势较为明显,从云阳至秭归断面均表现为沿程增加趋势. Bio-P相对含量为2. 78%～7. 05%,整体而言,三峡水库干流沉积物内源释放风险较小.沉积物生物可利用磷与有机质含量呈显著正相关（P <0. 05,N=50）,有机质的分布和转化将影响三峡水库沉积物中磷的迁移和转化.更多还原

【Abstract】 To investigate the vertical distribution characteristics of phosphorus in the main stream sediments of the Three Gorges Reservoir（ TGR）,column sediment samples were collected from 5 sites in October 2010,and sediment particle size,organic matter contents,and mineral compositions were analyzed. Investigation of the contribution rate of phosphorus released from column sediments in the TGR was also conducted. The results show that the sediment p H is between 7. 3-7. 8. The mainstream column sediment is mainly constituted by silt and clay,which account for 49. 4%-78. 6% and 20. 6%-50. 6% of total sediments,while sand represents less than4. 4%. Median grain size of each sampling site presented a phased increase or decrease trend. The organic matter content was between12. 94 g·kg^-1 and 53. 43 g·kg^-1,and it tended to slightly increase from upstream to downstream. The C/N ratio in the sediment was between 4. 00 and 11. 64,and organic matter content was mainly affected by terrigenous input. Total phosphorus（ TP） content was between 861. 86 mg·kg^-1 and 1024. 54 mg·kg^-1,and it exhibited negligible change in vertical distribution. There is no obvious enrichment phenomenon of phosphorus for column sediment. The major component of sediment TP is calcium bound phosphorus（ Ca-P,47. 83%-73. 90%）,and there are various trends for phosphorus distribution in different sampling sites. Exchangeable phosphorus（ Ex-P）,aluminum-bound phosphorus（ Al-P）,and iron-bound phosphorus（ Fe-P） in the 0-4 cm surface sediment of each sampling sites was relatively high. For most sampling sites,no obvious change of phosphorus fractions in 16-20 cm of sediment was detected.Bioavailable phosphorus（ the sum of Ex-P,Al-P,and Fe-P） accounted for 2. 78%-7. 05% of TP,indicating that bioavailability of phosphorus in the column sediments is low. The contents of bioavailable phosphorus and organic matter were significantly and positively correlated（ P < 0. 05,N = 50）. The distribution and transformation of organic matter will affect the migration and transformation of sediment phosphorus in the TGR.更多还原