除了吞没地面和改变美国东南部的生态系统，葛还可能增加该地区的臭氧污染。这种亚洲入侵植物是在20世纪早期种植的，原本用于帮助控制侵蚀。它是一种快速生长的豆科植物，以很高的速率固定大气中的氮。由于固氮植物的入侵可能影响到土地和大气环境，Jonathan Hickman及其同事通过比较没有受影响以及被葛入侵的土壤的氮流量，从而调查了葛对于该地区的空气质量的影响。
这组科学家报告说，氮氧化物（臭氧的前体）的排放在被入侵土壤中几乎加倍。这组作者使用了一种化学运输模型预测了氮氧化物增加的效应，并且提出了一种情景，即和没有葛的情景相比，该地区的一些地方的高臭氧天数随着葛的入侵加剧而增加了35%以上。这组科学家提出，这项研究确立了入侵植物和臭氧形成之间的一个可测量的联系。这组作者说，除了它对地面的视觉影响以及它影响环境变化的潜力，葛的生存范围也可能随着全球温度增加而扩展。
推荐原文出处：
PNAS doi: 10.1073/pnas.0912279107
Kudzu (Pueraria montana) invasion doubles emissions of nitric oxide and increases ozone pollution
Jonathan E. Hickmana,1,2, Shiliang Wub,3, Loretta J. Mickleyb, and Manuel T. Lerdauc
The nitrogen-fixing legume kudzu (Pueraria montana) is a widespread invasive plant in the southeastern United States with physiological traits that may lead to important impacts on ecosystems and the atmosphere. Its spread has the potential to raise ozone levels in the region by increasing nitric oxide (NO) emissions from soils as a consequence of increasing nitrogen (N) inputs and cycling in soils. We studied the effects of kudzu invasions on soils and trace N gas emissions at three sites in Madison County, Georgia in 2007 and used the results to model the effects of kudzu invasion on regional air quality. We found that rates of net N mineralization increased by up to 1,000%, and net nitrification increased by up to 500% in invaded soils in Georgia. Nitric oxide emissions from invaded soils were more than 100% higher (2.81 vs. 1.24 ng NO-N cm?2 h?1). We used the GEOS-Chem chemical transport model to evaluate the potential impact of kudzu invasion on regional atmospheric chemistry and air quality. In an extreme scenario, extensive kudzu invasion leads directly to an increase in the number of high ozone events (above 70 ppb) of up to 7 days each summer in some areas, up from 10 to 20 days in a control scenario with no kudzu invasion. These results establish a quantitative link between a biological invasion and ozone formation and suggest that in this extreme scenario, kudzu invasion can overcome some of the air quality benefits of legislative control.
