红枫湖后午沉积物磷形态与生物有效磷的垂向分布及疏浚深度推算

Vertical Distributions of Phosphorus Forms and Bioavailable Phosphorus in the Sediments of Houwu from Hongfeng Lake and Calculation of Environmental Dredging Depth

以贵州红枫湖后午重污染沉积物为研究对象,对沉积物柱芯按每2cm分层,研究了沉积物中含水量、孔隙度、磷形态与生物可利用磷的垂向分布规律,并推算出污染沉积物的环保疏浚深度。结果表明,含水量和孔隙度在沉积物上部30cm内递减,30cm往下剧减。沉积物中不同磷形态、生物有效磷的垂向分布规律相似,分别在6～12cm和15～16cm两个层段出现了转折,在底部30cm后趋于稳定。沉积物表层16cm中NaOH-P和有机磷含量的剖面变化,反映了红枫湖近20年来水环境富营养化的演变过程。根据含量拐点法和环保疏浚经济成本的考虑,可将后午区域疏浚层的深度定为30cm。

The heavily polluted sediment cores were collected from the Houwu area in the Hongfeng Lake, and sliced into 2-cm sections. The vertical distributions of water content, porosity, phosphorus （P） forms and its bioavailability in the sediments were analyzed, in order to calculate the environmental dredging depths at the Houwu site. The results showed that water con- tent and porosity decreased gradually in the upper 30 cm layer, and then decreased rapidly downwards. Similar trend was ob- served for various P forms and bioavailable P throughout the sediment profile. Two transitions occurred at the layer depths of 6 -12 cm and 15-16 cm, and tended to become stable below 30 cm. Vertical variations in NaOH extractable P and organic P at the top 16-cm layer reflected the eutrophication process in the Hongfeng Lake during recent 20 years. According to the varia- tion trend of P species in the sediment cores and the economic restriction of environmental dredging, the dredging depth for the studied area was determined as 30 cm.