宜昌城区绿地景观格局与大气污染的关系

在湖北省宜昌市中心城区4种景观绿地分布格局分析的基础上，对比观测了各景观中的环境噪声和大气SO2、NOx、TSP含量。结果表明，以无绿化道路廊道和建筑铺装斑块为主要景观构成的对照景观绿地破碎化指数最高(18．1253ind·hm^-2)，绿化覆盖率仅为1．00％，其景观中环境噪声较大、大气TSP含量高(0．4918mg·m^-3)；大面积绿地斑块占优势的景观绿化覆盖率高(达43．59％)，绿地破碎度指数最小(0．4539 ind·hm^-2)，与对照景观相比，大气噪声减弱28．12％，TSP含量降低86．42％；中小面积绿地斑块和绿化廊道呈均匀分布的景观绿化覆盖率(11．34％)和绿地破碎度指数(2．7511 ind·hm^-2)均较低，与对照景观相比平均滞尘率为46．62％；以绿化廊道占绝对优势的景观绿化覆盖率仅为6．13％，绿地破碎度指数均较高(6．8700 ind·hm^-2)，绿化廊道密度指数最大(0．8443hm·hm^-2)，其景观中环境噪声、TSP和NOx含量分别比对照景观增加21．47％、5．08％和9．06％.可见，在城市景观中绿地斑块平均面积越大、破碎度指数越低，则其对大气污染净化的作用越大。

Relationship between urban green-land landscape patterns and air pollution in the central district of Yichang city

In this paper, four types of landscape structures and their green-land landscape patterns, including the landscapes of dominant green-land patch pattern, even green-land patch pattern, dominant wooded corridor pattern and building or concrete covering pattern (control) in the central district of Yichang city in Hubei Province, were analyzed respectively on the basis of landscape ecological theory. The atmospheric noise and the contents of SO2, NOx and total suspension particle (TSP) of the landscapes were monitored respectively by comparative method. The results showed that the landscape of building or concrete covering pattern (control) was mostly composed of woodless corridors and building or concrete covering patches with the tiptop green-land fragmentation index (18.125 3 ind x hm(-2)) and only had 1.00% green-land coverage, which had a relatively higher atmospheric noise and the highest TSP content in the landscape. The landscape of dominant green-land patch pattern had the highest green-land coverage (up to 43.59%) dominated by great green-land patches and the least fragmentation index (0.453 9 ind x hm(-2)), in which, the atmospheric noise weakened by 28.12% and the TSP content reduced significantly by 86.42%, comparing to the control. The landscape of even green-land patch pattern had the relatively lower green-land coverage (11.34%) and fragmentation index (2.751 1 ind x hm(-2)), which was mainly composed of the middle or small green-land patches and wooded corridors with a regular distribution. In the landscape, the TSP content reduced obviously by 46.62% of the control, while the effect of dust retention was only 53.95% of that in the landscape of dominant green-land patch pattern. In the landscape of dominant wooded corridor pattern, which was a traffic center and turned into a main pollution resource in the city, there were a relatively higher green-land fragmentation index (6.870 0 ind x hm(-2)) and the highest wooded corridor density (0.844 3 hm x hm(-2)) with only 6.13% green-land coverage, and the atmospheric noise and the TSP and NOx content increased by 21.47%, 5.08% and 9.06%, respectively, comparing to control. It was obvious that the greater the average area of the green-land patch and the lower the fragmentation index of green-land patches, the more effective the green-land on purifying air pollution.