交替冻融对东北典型土壤浸提液碳氮污染指标的影响

摘要

The effects of freeze-thaw cycles (FTCs) on the soluble contaminants in black soil (BS) , dark brown soil (DS) and paddy field soil (PS) were investigated. The results showed that, after 15 FTCs treated between -20 ℃ and 20 ℃ , the CODCr mass concentration in the extract of BS samples decreased by 36% ; the CODCr in the extract of PS samples increased by 8% ; and, the CODCr in the extract of DS samples showed no obvious change. The NH4 + -N in the extract of BS samples decreased by 22% ; the NH4 + -N in the extract of PS samples increased by 84% ; and, the NH4 + -N in the extract of DS samples showed no obvious change. The NO3- -N in the extracts of BS and DS samples increased by 130% and 110% respectively. In contrast, the NO3 --N in the extract of PS samples showed no obvious change. The amount of oxygen included was a key factor determining the increase or decrease of CODCr, NH4+-N and NO3 --N mass concentrations in the extracts of the soil samples. CODCr and NH4 +-N mass concentrations would probably decrease in the presence of oxygen, while NO3- -N mass concentration would increase in anoxic conditions, and vice versa. The mass concentration of TN in the extracts was mainly determined by the C/N ratio in the soil. In this research, the TN in the extracts of BS, DS and PS samples increased by 30% , 35% and 39% respectively.%以黑土、暗棕壤和水稻土为例,试验研究了交替冻融对土壤溶解性污染物的影响.结果表明,15次交替冻融后(在-20和20℃进行冻融处理),黑土浸提液的ρ(CODcr)下降了36%,水稻土浸提液上升了8%,暗棕壤浸提液未出现明显变化;黑土浸提液的ρ(NH4+-N)下降了22,水稻土浸提液上升了84%,暗棕壤浸提液未出现明显变化;黑土和暗棕壤浸提液的p(NO(3)-N)分别上升T 1.3和1.1倍,而水稻土未出现明显变化.土壤浸提液ρ(CODc.).ρ(NH4 9-)和p(N03--N)的变化主要取决于土壤含氧水平,有氧条件下浸提液的ρ(CODcr)和ρ(NH+-N)降低而ρ(N03-N)升高,缺氧条件下则相反.土壤浸提液的ρ(TN)主要取决于土壤C/N,冻融后黑土、暗棕壤和水稻土浸提液的ρ(TN)分别上升了30%,35%和39%.