基于激光吸收光谱技术的太湖流域稻田氨挥发研究

氨挥发是太湖流域农田氮肥损失的重要途径之一。本试验采用高时间分辨率的TDLAS-BLS技术研究太湖流域稻田追肥期氨挥发规律及其影响因素。结果表明：追肥后稻田上方空气中氨浓度白天明显大于夜间，而且瞬时波动较大。稻田氨挥发速率呈现先上升后下降的趋势，峰值出现在施肥后的2~3天，且氨挥发仅持续一周左右。分蘖期氨挥发速率和损失率均大于抽穗期，氨挥发损失率分别为36.6%、23.0%。氨挥发集中在较短时间内，分蘖期、抽穗期施肥后前四天的累积氨挥发量分别占总氨挥发损失的80%、84%。分蘖期风速、光照、气温对稻田氨挥发均具有明显的促进作用，其中光照的作用更为显著；抽穗期风速和气温对氨挥发的影响较低。降雨对氨挥发具有强烈的抑制作用，降雨期间是影响氨挥发产生的主要因素。

Ammonia Emission from Paddy Field Measured by Laser Absorption Spectroscopy in Taihu Lake Region

Ammonia emission is one of the important pathway of nitrogen fertilizer loss from farmland in Taihu Lake region. In order to study the ammonia emission dynamics and influencing factors of paddy field in the Taihu Lake region, the TDLAS-BLS method with high-temporal resolution was used in this experiment. The results showed that, compared with the night time, the concentration and variability of ammonia above the rice canopy was significantly higher in daytime after fertilization. Ammonia emission increased rapidly and reached a maximum value 2-3 days after fertilization. After this maximum, emissions decreased rapidly. Ammonia emission loss in tillering stage (36.6%) were higher in panicle stage (23.0%), which was mainly concentrated in the initial four days after fertilizer application, and accounted for 80% and 84% of total ammonia loss for tillering stage and panicle stage, respectively. In tillering stage, the wind speed, solar radiation and air temperature obviously promoted the ammonia emission, and solar radiation was the most significant influencing factor. The effect of wind speed and temperature on the ammonia emission in panicle stage was low. Precipitation significantly decreased ammonia emission rate, and was the main factor influencing ammonia emission during the rainfall.