The contribution of soil biogenic NO emissions from a managed hyper-arid ecosystem to the regional NO₂ emissions during growing season

Abstract

Abstract. A study was carried out to understand the contributions of soil biogenic NO emissions from managed (fertilized and irrigated) hyper-arid ecosystem in NW-China to the regional NO2 emissions during growing season. Soil biogenic NO emissions were quantified by laboratory incubation of corresponding soil samples. We have developed the Geoscience General Tool Package (GGTP) to obtain soil temperature, soil moisture and biogenic soil NO emission at oasis scale. Bottom-up anthropogenic NO2 emissions have been scaled down from annual to monthly values to compare mean monthly soil biogenic NO2 emissions. The top-down emission estimates have been derived from satellite observations compared then with the bottom-up emission estimates (anthropogenic and biogenic). The results show that the soil biogenic emissions of NO2 during the growing period are (at least) equal until twofold of the related anthropogenic sources. We found that the grape soils are the main summertime contributor to the biogenic NO emissions of study area, followed by cotton soils. The top-down and bottom-up emission estimates were shown to be useful methods to estimate the monthly/seasonal cycle of the total regional NO2 emissions. The resulting total NO2 emissions show a strong peak in winter and a secondary peak in summer, providing confidence in the method. These findings provide strong evidence that biogenic emissions from soils of managed drylands (irrigated and fertilized) in the growing period can be much more important contributors to the regional NO2 budget (hence to regional photochemistry) of dryland regions than thought before.