Environmental effect of sediment dredging in lake: Ⅲ. Influence of dredging on denitrification in sediments

Abstract

通过为期一年的疏浚模拟试验,在试验室培养疏浚与对照柱样,研究了底泥疏浚对沉积物反硝化过程的影响.沉积物反硝化速率的测定采用经典的乙炔抑制法,研究结果表明,在一年的试验周期内,疏浚和对照柱沉积物的反硝化速率分别为6.9-26.9nmol/(g·h)和21.6-102.7nmol/(g·h),除2006年的2月外的其他月份,疏浚沉积物的反硝化速率显著(P<0.05)低于未疏浚对照沉积物,同时还研究了环境因子对沉积物反硝化速率的影响,结果表明,疏浚和对照沉积物的反硝化速率都受温度的控制,硝态氮浓度是疏浚和对照沉积物反硝化速率的主要限制因子,有机碳对疏浚沉积物的反硝化速率有影响,但对未疏浚对照沉积物的反硝化速率没有影响.疏浚后短期内沉积物反硝化速率低于未疏浚对照沉积物,可看作是底泥疏浚在富营养华水体脱氮方面的一个负效应.;A laboratory experiment for studying the effects of sediment dredging on denitrification process was carried out through a one-year incubation of undredged sediments (control) and dredged sediment cores. Denitrification rates in the sediments were estimated by means of the acetylene blockage technique. During the experiments, the denitrification rates in the undredged and dredged sediments ranged from 21.6 to 102.7nmol/(g·h) and from 6.9 to 26.9nmol/(g·h), respectively. The denitrification rates in the undredged sediments were significantly higher (P < 0.05) than those in the dredged sediments throughout the incubation period, with an exception of February 2006. The relative importance of various environmental factors on denitrification was assessed, and the results indicated that denitrification rates in both undredged and dredged sediments were regulated by temperature controls. Nitrate was likely to be the key factor limiting denitrification rates in both undredged and dredged sediments. Organic carbon played some role in determining the denitrification rates in the dredged sediments, but not in the undredged sediments. Potential denitrification in the early dredged sediments couldn't reach a high rate as that in undredged sediments, which should be considered as a potential negative effect for nitrogen removal.