<span id="ChDivSummary" name="ChDivSummary" class="abstract-text">通过分析大气活性氮对广布野生植物葎草（Humulus scandens）叶片氮的影响,探索葎草作为大气氮沉降指示植物的可能性。试验采集了华北平原6个地点的葎草植物叶片,测量叶片全氮、δ15N值及其生境附近的大气活性氮（NH3-N和NO2-N）浓度。研究发现葎草叶全氮含量与大气中NH3-N浓度有很强的相关性,而与NO2-N及大气总活性氮浓度相关性很小;叶δ15N值与NH3-N和大气中总活性氮浓度均显著相关,而与NO2-N关系不显著。植物嫩叶比成熟叶的全氮含量更高,嫩叶δ15N对NH3浓度变化也更敏感。本研究结果初步表明,葎草嫩叶的全氮含量和δ15N值对NH3-N浓度有较好的指示作用,但此结论仍需更多实验数据的支持。</span>

Bioindication of nitrogen(N) deposition is concerned by environmental scientists,but few higher plants have been reported to indicate variations in atmospheric N deposition.Leaf total N concentration and δ15N value of a wide-spread herbaceous creeper Humulus scandens from the six sites in the North China Plain were investigated,together with the atmospheric reactive N concentrations at each site,to explore the impact of N deposition on H.scandens,and the possibility of H.scandens as a bioindictor of N deposition.The results showed that there was a strong correlation between leaf total N and atmospheric NH3-N,and a weak correlation between leaf total N and atmospheric NO2-N or total atmospheric reactive N.The tender leaves had higher N concentration and δ15N value,and showed a steeper slope of leaf total N and δ15N along the gradient of atmospheric NH3-N concentration,compared with the adult ones of H.scandens.Our study suggests that H.scandens might serve as a potential bioindicator of atmospheric NH3-N concentration and deposition with the N concentration and δ15N value in its tender leaves being analyzed,though further evidence is needed.

Based on field measurements, the effects of atmospheric reactive nitrogen (ARN) on the middle/trace element concentrations in the leaves of wild plant humulus scandens were analyzed. Leaves of H. scandens were collected from six sites around Beijing in the North China Plain, and the concentrations of Ca, Mg, S, Fe, Mn, Cu, Zn, B, and Na in the leaves were determined with inductively coupled plasma atomic emission spectrometry (ICP-AES). The results showed that element concentrations in leaves ranked as Ca (41 106) > S (8 370) > Mg (6 628) > Fe(476) > Na (92) > B (78) > Mn (49) > Zn (38) > Cu (15) mg x kg(-1) dry matter; There were no significant difference in any of the individual element in the H. scandens leaves along the gradient of ARN, suggesting that the increasing demand of H. scandens for middle/trace elements, induced by the enhanced nitrogen availability from ARN, was not yet beyond the nutrient-supply limits of the local soils. This study offers reference to scientific assessments of the middle/trace element status in terrestrial herbaceous plants under the global background of increasing nitrogen deposition.