原位洗脱技术对凉水河底泥中氮、磷释放特征的影响

为探讨新兴底泥原位修复技术—原位洗脱技术对城市河流凉水河底泥中氮、磷释放的抑制作用,于现场采集洗脱前后样品并设计室内静态模拟实验,分析了实验期间洗脱组和对照组上覆水中${{rm{NH}}_4^ + }$-N、${{rm{NO}}_3^ - }$-N、TN、${{rm{PO}}_4^{3 - }}$-P、TP浓度和释放速率变化特征。结果表明：洗脱组释放第30天时,${{rm{NH}}_4^ + }$-N由底泥向上覆水中平均释放速率(−6.51±0.32) mg·(m²·d)⁻¹,对应上覆水中${{rm{NH}}_4^ + }$-N平均浓度为0.52 mg·L⁻¹,较对照组下降了89.4%;${{rm{PO}}_4^{3 - }}$-P和TP平均释放速率较对照组降低了78.1%和83.0%,上覆水中TP平均浓度为0.22 mg·L⁻¹,较对照组下降了68.1%。原位洗脱技术对底泥中${{rm{NH}}_4^ +} $-N、${{rm{PO}}_4^{3 - }}$-P释放的抑制作用主要通过对有机氮、磷物质的削减和水-沉积物界面还原环境的改善来实现。

Effect of in-situ physical elution technology on release features of nitrogen and phosphorus in the sediment of Liangshui river

In this study, a new in-situ remediation technology-in-situ physical elution technology was used to conduct the inhibition experiments on nitrogen and phosphorus release from the sediment of Liangshui River. The in-situ samples before and after elution were collected, then the lab static simulation tests were also designed. Variation characteristics of contents and release rate of ${rm{NH}}_4^ + $-N, ${rm{NO}}_3^ - $-N, TN, ${rm{PO}}_4^{3 - }$-P, TP in the overlying water of the elution group and control group were analyzed. The results were showed that for the elution group, the average ${rm{NH}}_4^ + $-N release rate from sediment to the overlying water was (−6.51±0.32) mg·(m2·d)−1 on the 30th day of the release test, and the average ${rm{NH}}_4^ + $-N concentration in the overlying water reached 0.52 mg·L−1, which decreased by 89.4% compared to the control group. The average ${rm{PO}}_4^{3 - }$-P and TP release rates decreased by 78.1% and 83.0% compared to the control group, respectively. The average TP concentration in the overlying water reached 0.22 mg·L−1, which was 68.1% lower than the control group. The inhibition of ${rm{NH}}_4^ + $-N and ${rm{PO}}_4^{3 - }$-P release from the sediment by in-situ physical elution technology is mainly realized through the reduction of organic nitrogen and phosphorus substances and the amelioration of reducing environments in water-sediment interface.