合肥城郊典型排水沟渠沉积物磷形态及其释放风险

Fractions and release risk of phosphorus in surface sediments of a drainage ditch in the suburban of Hefei,China

为弄清合肥市城郊排水沟渠—关镇河水体沉积物磷赋存形态及其污染特征,于2013年9月—2014年6月,在沟渠上选取8个采样点,逐月采集水样和表层沉积物样,解析沉积物的磷赋存形态及其时空变化特征,并对磷的潜在释放风险进行分析。结果表明：关镇河水体氮、磷污染严重;沉积物中TP含量处于1 430.10~1 941.26 mg/kg范围,平均为1 734.42 mg/kg;沉积物各形态磷含量由高到低排序为：OP〉Fe-P〉Ca-P〉De-P〉Al-P〉Oc-P〉Ex-P;生物有效性磷平均值为464.01 mg/kg,占TP的26.81%;广义生物有效性磷的平均含量为1 226.92 mg/kg,占TP的71.00%;PSI变化范围为18.31~69.96 mg P/（100 g）·（μmol/L）,且沉积物磷释放风险春夏季高于秋冬季。

To investigate the forms and pollution characteristics of phosphorus in the sediments of Guanzhenhe Stream,eight sampling points were chosen in the study ditches. Both surface water and sediment samplings were collected monthly to analyze the forms and space-time variations of phosphorus and to evaluate its potential release risk from September,2013 to June,2014. The results showed that the water quality of Guanzhenhe Stream was seriously polluted by nitrogen and phosphorus pollutants. The contents of total phosphorus（TP） in the sediments ranged from 1 430.10 to 1 941.26 mg/kg with an average of 1 734.42 mg/kg. The order of different phosphorus forms contents in the sediments was OP 〉 Fe-P 〉 Ca-P 〉 De-P 〉 A1-P 〉 Oc-P 〉 Ex-P. The average contents of bio-available phosphorus and universal bio-available phosphorus in the surface sediments were 464.01 and 1 226.92 mg/kg, respectively, and accounted for 26.81% and 71.00% of TP, respectively. And the phosphorus sorption index（PSI） of the surface sediments ranged between 18.31 and 69.96 mgP/（100g） ： （ μmol/ L）. Generally,a conclusion could be drawn that phosphorus release risk of surface sediments in the Gauzhenhe Stream was higher in spring and summer than that in autumn and winter according to the monthly changes of PSI.