Research On Greenhouse Gas Concentration Distribution Characteristics And Comparison Of N₂O Emission Monitoring Methods In Facility Vegetable Field

In this study,the relationship between the final greenhouse gas emissions of greenhouse vegetable ecosystems and soil discharge was analyzed by observing the spatial and temporal distribution of greenhouse gas concentrations in greenhouses and the greenhouse greenhouse gas emissions measured by box method.And try to introduce the inversion gas diffusion model,combined with the inverse dispersion techniqueand the box method to estimate the greenhouse gas emission flux of the vegetable field,quantify the difference of the results,compare the emission law and characteristics,and objectively evaluate the difference.the reason.The final conclusions of this study are as follows:?1?In the short-term high-frequency monitoring,the N₂O emission characteristics of the vegetable field and the N₂O concentration distribution trend in the greenhouse tend to be consistent;the CO₂ emission characteristics of the soil and the CO₂ concentration distribution in the greenhouse are opposite.It can be seen that the main source of N₂O emissions in the shed is the greenhouse soil,and CO₂ is multi-source.?2?The characteristics of N₂O concentration at different heights in the shed are consistent,which is consistent with the N₂O flux characteristics measured by the static box method.The N₂O concentration decreases with height,which is higher than the external background concentration,indicating that the greenhouse has a higher gas concentration.Strong retention,a small environment of high concentration of N₂O is formed in the shed.?3?Monitoring the greenhouse gas emissions of the vegetable field by static box/gas chromatography is available.The measured flux results from 9:00 to 12:00 daily represents the average daily emission flux,but may not be sufficient to balance the greenhouse.Time variability in N₂O emissions.Soil N₂O flux results may have an error of 14%-67%,and soil CO₂ flux results may have an error of 6%-17%.?4?The automatic sampling device of the inverse dispersion techniquecan obviously capture the N₂O concentration change above the shed area.The N₂O concentration range of the shed area at the height of 3.5 meters is 0.673-0.689 mg·m^-3,and the N₂O concentration range during the planting period.From 0.695 mg·m^-3 to 0.716 mg·m^-3,the planting period is significantly higher than the vacant period.?5?The static box/meteorological chromatographic method and the inverse dispersion techniquehave good consistency when observing the daily N₂O emission characteristics of the vegetable field.The average three-day emission flux measured by static chamber/weather chromatography was 252.51?g·m^-2·h^-1,which was higher than the observational gas diffusion model observation result of 192.21?g·m^-2·h^-1,which was 26.75%higher.?6?In the static box/meteorological chromatography and inversion gas diffusion model,the observation results of the two methods in the whole growing season of the greenhouse tomato also have good consistency.During the whole growing season,the static box The measured net soil flux was 1817.49g·hm^-2,and the emission factor was0.45%.The net gas flux of the inverse dispersion techniquewas 1250.95 g·hm^-2,and the emission factor was 0.32%,which was compared with the static box.29%lower.In summary,the static tank/gas chromatography alone can not balance the greenhouse gas emissions of the vegetable field in time and space.The inverse dispersion techniqueand the static box/gas chromatography method proposed to introduce the N₂O flux in the vegetable field planting area have good consistency,indicating that the inverse dispersion techniqueis suitable for observing the N₂O emission of vegetable fields.The observation results are significantly lower than the static box/gas chromatography method,which provides a reference for the existing measurement methods and provides a new idea for establishing a diversified N₂O emission monitoring system.