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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
5 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
10 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
15 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 pe20
riod can be much more important contributors to the regional NO2 budget (hence to regional photochemistry) of dryland regions than thought before.
