论文部分内容阅读
箱法被广泛用于监测土壤N2O排放通量,但在原位采集高浓度土壤N2O、全天候监测N2O通量变化、动态研究土壤剖面N2O的行为等方面存在弊端。本研究通过室内模拟硅胶管对N2O的通透性,探索硅胶管用于原位采集土壤气样的理论可行性。田间试验设施用铵态氮肥(NH4+)、施用硝态氮肥(NO3-)及施用硝态氮肥加葡萄糖(NO3-+C)等3个处理,同时安置硅胶管和采样箱,验证硅胶管法在原位采集高浓度土壤N2O气样、监测土壤N2O浓度以及排放通量的实际效果,并与箱法进行比较。结果表明,硅胶管内外的N2O气体经2.9 h达到95%的平衡,完全能满足大田采样要求;用硅胶管法原位采集高浓度土壤N2O气样的效果显著优于箱法采样。其浓度变化表现出明显的时间规律,浓度梯度法计算的N2O排放通量与箱法测定结果呈显著正相关,但数值偏低;偏低的程度取决于采样位置和土壤中N2O产生位置的匹配程度。建议采用埋于土壤表层的硅胶管计算地面N2O排放通量,或在不同土层埋入硅胶管研究土壤剖面N2O行为的时空变异。
Box method is widely used to monitor soil N2O flux. However, there are some disadvantages in the field, such as collecting N2O in situ, monitoring the change of N2O flux around the clock, and dynamically studying the behavior of N2O in soil profile. In this study, we simulate the permeability of silica tube to N2O indoors to explore the theoretical feasibility of using silica gel tube for in situ sampling of soil gas samples. The field test facilities used ammonium nitrate (NH4 +), application of nitrate nitrogen (NO3-) and application of nitrate nitrogen fertilizer plus glucose (NO3- + C) and other three treatments. Silicone tubing and sampling boxes were placed at the same time. In situ collection of N2O gas samples from high concentrations of soils, monitoring of N2O concentrations in soil, and actual effects of emission flux were compared with those from the box method. The results showed that the N 2 O gas inside and outside the silica gel tube reached a 95% balance after 2.9 h, which could completely meet the field sampling requirements. The silica gel tube method was superior to the box method in situ sampling of N 2 O in high concentration soil samples. The concentration of N2O emission showed a significant temporal pattern. The N2O flux calculated by the concentration gradient method was significantly positively correlated with the results of the box method, but the value was low. The low degree of N2O emission was determined by the match between the sampling location and the N2O production in the soil degree. It is suggested to calculate the N2O emission flux from the surface by using silicone tube embedded in the soil surface or to study the spatiotemporal variation of N2O behavior in the soil profile by embedding silicone tube in different soil layers.