Status: this discussion paper is a preprint. It has been under review for the journal Biogeosciences (BG). The manuscript was not accepted for further review after discussion.
Atmospheric dry and wet nitrogen deposition in agro-pastoral catchments of the China and Mongolia Altay
Jin Ling Lv,Andreas Buerkert,Guo Jun Liu,Chao Yan Lv,Xi Ming Zhang,Kai Hui Li,and Xue Jun Liu
Abstract. Very few comparative studies of nitrogen (N) deposition in agroecosystems have been conducted along landuse and altitude gradients. In an effort to fill this gap of knowledge we selected three typical, interconnected landuse systems (cropland, mountain grassland and plain grassland)at six sampling sites in the transboundary Altay Mountains of NW China and SW Mongolia to compare the dynamics and amounts of wet and dry N deposition. During 12 months from June 2014 to May 2015 dry and wet N deposition through middle volume total suspended particulates (TSP), passive samplers and precipitation collectors were monitored. The croplands had the highest concentrations of NH4+-N (1.6 mg N L−1 in China and 2.0 mg N L−1 in Mongolia) and of NO3−-N (1.0 mg N L−1 in China and 1.2 mg N L−1 in Mongolia) in precipitation compared with the other land use types for wet deposition. In contrast, the Mongolian mountain grasslands experienced the highest wet deposition (3.2 kg N ha−1 yr−1) which was at least partly due to higher summer precipitation (161 mm), the second highest wet deposition occurred on Chinese cropland with 3.1 kg N ha−1 yr−1 while wet deposition in other landuse types ranged from 1.8 to 2.5 kg N ha−1 yr−1. Chinese cropland had the highest NH3 (3.1 μg N m−3) and NO2 (3.8 μg N m−3) concentrations and dry N deposition (15.3 kg N ha−1 yr−1) among all landuse types while Mongolian cropland had dry N deposition of 8.9 kg N ha−1 yr−1. Chinese cropland (18.4 kg N ha−1 yr−1) had the highest total N deposition, followed by the Mongolian cropland with 10.7 kg N ha−1 yr−1 and the Mongolian mountain grassland with 10.5 kg N ha−1 yr−1. NH4+-N concentration were negatively correlated with precipitation (P < 0.05). Concentration of NH3 correlated positively with air temperature (P < 0.05) likely reflecting promoting effects of temperature on NH3 emissions whereas NO2 correlated negatively with temperature. Over all, croplands in China had 72 % higher N deposition than in Mongolia whereas the reverse was true for mountain grasslands which received 31 % more Nin Mongolia.
How to cite. Lv, J. L., Buerkert, A., Liu, G. J., Lv, C. Y., Zhang, X. M., Li, K. H., and Liu, X. J.: Atmospheric dry and wet nitrogen deposition in agro-pastoral catchments of the China and Mongolia Altay, Biogeosciences Discuss. [preprint], https://doi.org/10.5194/bg-2017-55, 2017.
Received: 20 Feb 2017 – Discussion started: 10 Apr 2017
Very little research has been conducted to quantify atmospheric N deposition in agro-pastoral transition zones. Based on this, we chose a typical agro-pastoral transition zone in the border area of China and Mongolia and used scientific method to compare the dynamics and amounts of wet and dry N deposition in this area. This will hopefully supply the scientific evidence required to introduce more rational N application and manure management strategies for similar areas throughout central Asia.
Very little research has been conducted to quantify atmospheric N deposition in agro-pastoral...