| Due to the peculiar morphological structure and biological characteristics, mosses have been widely employed in indicating and monitoring environmental change and atmospheric deposition. The stable isotopes are reliable tools in identifying the source and fate of elements in varying environments and understanding the relationships between plants and environment. In order to explore the reliability of moss used as biological indicator to monitor atmospheric nitrogen pollution, the spatial distribution of atmospheric nitrogen deposition of Jiangxi Province and trace atmospheric nitrogen source. By combining moss bio-indicating method with nitrogen isotopic technique, this thesis was mainly around a topic on using 515N and nitrogen concentration in mosses for indicating atmospheric N deposition. The author packed 183 mosses (H.microphyllum (Hedw.)) in Jiangxi Province. By using elemental contents and the relation between N deposition and moss N, the level of N deposition at Jiangxi area could be quantified. Combined with the correlation significant difference analysis in moss isotopic signatures to indicate the main sources and N form of atmospheric N deposition at Jiangxi area. This thesis has deepened the application of moss for monitoring environment and N deposition, and has provided geochemical references for the prevention and control of N pollutants at city area.(1) Bryophyte plants can be used as bio-indicator to monitor atmospheric pollution. Tissue the nitrogen content of moss in Jiangxi province increased from northeast to the southwest, reflecting the spatial distribution of atmospheric nitrogen deposition in Jiangxi Province. Trough t-test, significant difference (P<0.05) between urban suburban and rural tissue nitrogen content of moss in Jiangxi cities.We were found that tissue nitrogen content of the urban moss tissue (2.95±0.06%) was significantly higher than that of rural(2.73±0.05%) and suburban(2.56±0.76%).The average nitrogen isotope moss is-1.96±1.30 to -9.74±0.25%o in Jiangxi Province. Among them, tissues nitrogen isotope of moss in Shangrao is the lowest (-9.74±0.25‰), the highest is tissue nitrogen isotope of moss in Nanchang suburban-(1.96±1.30%o). Suburban tissue nitrogen isotope of moss (-1.96±1.30%o～-4.81±0.53%o) is higher than urban tissue nitrogen isotope (-3.72±0.71%o～-9.74±0.25%o).Though the average nitrogen isotope moss is from -3.11±0.44‰to 0.078±0.074%o in Chongren rural. More negativeδ15N values of urban mosses thanδ15N values of suburban and rural mosses. Indicating the rural area and cities are affected by different sources of nitrogen.(2) Through the relation between N deposition and moss nitrogen content, the level of N deposition at Jiangxi area could be quantified by the N contents of mosses. The general level of N deposition Jiangxi at area (28.81 kg-(hm2-a)"1～51.41 kg·(hm·a)-1) has exceeded the critical load for the vulnerable terrestrial ecosystems (5kg·(hm·a)-1～10kg·(hm·a)-1). Besides, the level of N deposition (33.26±10.88 kg·(hm·a)-1～34.57±8.75kg·(hm·a)-1) in the suburban area is lower than the urban site (39.66±11.07kg·(hm·a)-1～52.92±13.05kg·(hm·a)-1). For the first time, the level of N deposition in Jiangxi were quantified by nitrogen content in mosses, which is important for further studying the ecological effects of atmospheric N deposition and helpful for the protection of the ecosystems.The average nitrogen isotope moss in urban (-6.11±0.37%o), suburban (-3.75±0.34%o) and rural (-0.74±0.16%o) were significant difference exist (p<0.001), indicating there are affected by different sources of nitrogen.. More negativeδ15N values of urban mosses indicated that more NH3 was released from excretory wastes and sewage, while less negativeδ15N values of suburban and rural mosses suggested an important contribution from agricultural NH3 emission due to fertilizer application. This study found the regulation of mossδ15N variation (more negative at urban than suburban and rural) around Jiangxi Province dominated by NHx deposition. The main nitrogen form of atmospheric N deposition at Guiyang area was NHx, while the affected by the NOx was least. |
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