合肥城郊典型农田溪流水系统沉积物磷形态及释放风险分析

Phosphorus Fractions and Release Risk in Surface Sediments of an Agricultural Headwater Stream System in Hefei Suburban,China

2014年10月（秋季）和2015年4月（春季）,针对巢湖二十埠河流域某一典型农业源头溪流水系统,就水塘、支流、干流和深潭等4种溪流构成模式,分别采集17、16、14和13份表层沉积物样.在分析测试的基础上,解析沉积物的磷形态及其季节性变化特征;并以多元统计分析技术,对4种构成模式开展聚类分析和差异性分析;通过对沉积物磷吸附指数PSI的计算和相关性分析,定量评估磷素释放风险,识别主要影响因素.结果表明：1溪流水系统沉积物TP含量变化范围为137.517-1 709.229 mg·kg-1,均值为532.245 mg·kg-1,各形态磷的平均含量高低排序为：IP（350.347 mg·kg-1）〉OP（167.333mg·kg-1）〉Fe/Al-P（78.869 mg·kg-1）〉Ca-P（56.343 mg·kg-1）〉Ex-P（6.609 mg·kg-1）;2 4种构成模式中,各形态磷含量均表现出相同的变化趋势,即深潭〉干流〉支流〉水塘;3秋季时干流和深潭聚为一类、支流和水塘为另一类,春季时则干流、支流和深潭归为同一类;4方差分析表明,秋季时溪流不同构成模式之间的差异性指标更多;5沉积物PSI变化范围为24.49-69.94（mg·L-1）·（100 g·μmol）-1,且春季低于秋季,说明春季的磷素释放风险更高一些;6 PSI与Ex-P、IP和p H呈显著或极显著负相关性.

A typical water system of agricultural headwater stream in Chaohu Lake basin was selected as the study area,and 17,16,14 and 13 surface sediments were collected from the four styles of stream,respectively,including ponds,branches,main channel and mainstream deep pools,in October 2014（ in autumn） and April 2015（ in spring）. The forms and space-time variations of phosphorus in the sediments were analyzed. Clustering and variance analysis were conducted on the phosphorus forms data from the four styles of stream by means of multivariate statistical analyses. We quantified the phosphorus release risk（ PSI） and identified the main impact factors of PSI via calculating the phosphorus sorption index（ PSI） and the correlation analysis. The results showed that： 1 The contents of TP in the surface sediments ranged from 137. 517 to 1 709. 229 mg·kg- 1with an average value of 532. 245 mg·kg- 1,and the order of the average contents of phosphorus forms was IP（ 350. 347 mg·kg- 1） OP（ 167. 333 mg·kg- 1） Fe/Al-P（ 78. 869mg·kg- 1） Ca-P（ 56. 343 mg·kg- 1） Ex-P（ 6. 609 mg·kg- 1）; 2 The contents of phosphorus forms had the same trend in all the four stream styles,which was deep pool main channel branch pond; 3 In autumn,the deep pool and main channel were clustered into one class,while the pond and branch were clustered into the other class. In spring,branch,main channel and deep pool were clustered into the same class; 4 Variance analysis showed that the differences among the four stream styles were larger in autumn than in spring; 5 The PSI of the surface sediments ranged between 24. 49 and 69. 94（ mg·L- 1） ·（ 100 g·μmol）- 1. The PSI in spring was lower than that in spring,indicating that phosphorus release risk of surface sediment was higher in spring than in autumn. 6 PSI had a significant negative correlation with Ex-P,IP and p H.