巢湖表层沉积物磷的空间分布差异性研究

Spatial Distribution Character of Phosphorus Fractions in Surface Sediment from Chaohu Lake

通过对巢湖表层沉积物磷形态、有机质及粒径分布特征分析,与沉积物总磷历史数据进行对比,结合不同形态磷的剖面变化,探讨了内源磷释放风险.结果表明,巢湖表层沉积物TP自西向东呈递减趋势,平均含量为790 mg.kg-1,比20世纪80年代平均增加了55%,其中东半湖增加211 mg.kg-1、西半湖增加386 mg.kg-1.表层沉积物磷形态含量和分布有较大差别:铁铝结合磷(NaOH-Pi)和活性有机磷(NaOH-Po)含量占TP含量的42%,分别介于55～648 mg.kg-1和27～468 mg.kg-1范围,西半湖平均含量分别为331 mg.kg-1和225 mg.kg-1显著高于东半湖(147 mg.kg-1和91 mg.kg-1,P<0.01);相对而言,钙镁结合磷(Ca-P)和惰性磷(Res-P)含量在东西部湖区没有显著差别,分别占TP含量的18%和40%.沉积物TP含量随深度减少而增加,西半湖增加量高于东半湖,各种磷形态中NaOH-Pi和NaOH-Po的垂直变化规律与TP相似,是沉积物磷增加的主要形态.西半湖高活性磷、高有机质和多砂质粉砂的特征共同作用极大增加了沉积物中磷向上覆水中释放的风险.

Phosphorus fractions, organic matter and particle size of the surface sedimenl from Chaohu Lake were analyzed for spatial distribution and the risk of phosphorus release. The result showed that total phosphorus （TP） of surface sediment was 790 mg.kg-1, which was 55% higher than that in 1980s, with 386 mg.kg-1 higher in western lake and 211 mg.kg lhigher in eastern lake. NaOH-P1 of sediment ranged from 55 to 648 mg.kg- 1 , and occupied average 25 % of TP. NaOH-Po of sediment ranged from 27 to 468mg.kg - 1 , and occupied average 17% of TP. NaOH-Pi and NaOH-Po in western lake were 331 mg-kg-1 and 225 mg.kg-l, which were significantly higher than those in eastern lake. Ca-P and Res-P accounted for 18% and 40% of TP, and were equably distributed in the lake. TP, NaOH-Pi and NaOH-Po of sediment in the western lake increased intensively with the depth, while Ca-P and Res-P showed no significant change in the vertical profile in the lake. Profile of phosphorus fractions showed that NaOH-P~ and NaOH-Po were the dominant factions of the increasing phosphorus sedimentation in the western lake. Phosphorus of sediment in the western lake will release more easily to the water with higher organic matter and higher content of sandy silt.