DONG Yihui 1,2 , YU Shengpin 3 , ZHANG Shuyuan 2 , LI Jiale 2 , LIU Yajie 2 , DING Huijun 4 , XIONG Fan 2 , YE Hailong 3 , SUN Zhanxue 2
(1. Jiangxi Province Key Laboratory of the Causes and Control of Atmospheric Pollution, East China University of Technology, Nanchang 330013, China;
2. School of Water Resources and Environmental Engineering, East China University of Technology,
Nanchang 330013, China;
3. Jiangxi Institute Co. LTD of Survey and Design, Nanchang 330095, China; 4. Key Laboratory of Poyang Lake Water Resources and Environment of Jiangxi Province, Nanchang 330029, China)
Abstract: Poyang Lake is the largest freshwater lake in China, which is located in the Poyang Lake Basin ( PLB) , one of the most important grain-producing regions in Southern China. Human activities in particular the agricultural activities within the basin are highly intensive. Taking the shallow soils from the PLB as research objects, field investigations and laboratory analyses were conducted to determine the temporal and spatial distribution of inorganic nitrogen ( N) in the PLB. The content of inorganic nitrogen species in the shallow soils from the PLB irrigation area during the wet and dry seasons were: not detected (ND) -28 and 1 ~ 11 mg / kg for nitrate-N, with mean values of 7 mg / kg and 6 mg / kg, respectively; 4. 1 ~ 130. 0 and 1. 3 ~ 31. 1 mg / kg for ammonium-N, with mean values of 43. 0 mg / kg and 6. 5 mg / kg, respectively. The content of nitrite-N was below the detection limit during the wet season, and ND-0. 4mg / kg during the dry season with an average of 0. 1 mg / kg. Inorganic N in shallow soils is temporarily dominated by ammonium in the wet season and nitrate-N in the dry season. Spatially, nitrate- and ammonium-N contents in the layer L1 (0. 2-0. 4 meters deep) were higher than those in the layer L2 (0. 9-1. 1 meters deep) during both wet and dry seasons. The lithology of the unsaturated zone, soil pH, atmospheric precipitation, and human activities influenced the source and distribution of inorganic N in shallow soils. The distribution of inorganic nitrogen in the PLB irrigation area was mainly affected by atmospheric precipitation and N fertilizers. Results of the soil N input-output budget in Nanchang City indicates that N was primarily derived from human and animal manure, accounting for 70%of the total N input, while ammonia volatilization and denitrification were the major forms of N output respectively responsible for 43. 7% and 36. 6% of the total output.
Key words: Poyang Lake; irrigation area; shallow soil; inorganic nitrogen; nitrogen balance model
EARTH AND ENVIRONMENT Vol. 51, No. 5, Tot No.355 2023
