选取夏热冬冷地区合肥市天鹅湖3种不同类型绿地作为研究对象，并以空旷广场为对照，于2015年夏冬季分别测试了空气离子浓度、PM2.5浓度、温度、湿度、风速等指标，分析了3种不同类型绿地以及对照广场的空气负离子浓度和PM2.5浓度的时空特征，并进行了空气质量评价。结果表明，（1）实测样地的空气负离子浓度日变化较明显，呈现出上午高、下午低的趋势。同一时刻中对照广场空气负离子浓度最低，均低于3种不同类型绿地，峰值期间差异尤其明显。（2）夏冬季实测样地的空气负离子浓度由大到小依次为：疏林地、密林地、草地、对照广场。（3）实测样地的PM2.5浓度日变化较明显，呈双峰双谷型，即早中晚低、白天高。（4）夏季实测样地PM2.5浓度差异较显著，冬季不显著，且冬季PM2.5浓度均大于夏季。（5）夏冬季实测样地的空气负离子平均浓度差异不大，CI 指数接近，等级为 D，空气清洁度属于容许范围；而对照广场的空气负离子平均浓度显著低于3种不同类型绿地，CI指数最低，等级为E级，空气清洁度属于中污染。由此得出以下结论：（1）合理的绿地空间布局能够提高空气负离子浓度，降低颗粒物污染并改善空气质量；（2）空气负离子浓度与PM2.5浓度呈显著负相关；与相对湿度呈显著负相关，与风速呈显著正相关，与温度关系不明确。在此基础上进一步提出展望，建议对PM2.5浓度和空气负离子浓度展开实时监测并对结果进行对比分析，找出两者之间的相关关系。同时对不同季节、不同天气状况、不同下垫面结构的城市绿地进行进一步深入研究，探索有利于居民身心健康和休闲运动的城市绿地类型。%This study investigated three different types of green spaces around the Swan Lake in Hefei city, which is in Hot-summer and Cold-winter area. Taking the open square as control, the researcher measured, during 2015 summer and winter seasons, air ions concentration, PM2.5, temperature, relative humidity and wind speed. The study assessed the air quality by analyzing the spatial and temporal characteristics of the NAI concentration and PM2.5 concentrations of the three different types of green spaces in comparison to those of the open square. The results revealed, (1) NAI concentration of the measured plots diurnal variation is obvious, showing a trend high in the morning and low in the afternoon. At the same time, the NAI concentration on the open square is the lowest and the difference is particularly evident during the peak. (2) In summer and winter seasons, the NAI concentration of the measured plots exhibits a descending order as follows: woodland, dense woodland, grassland and the open square. (3) PM2.5 concentrations of the measured plots diurnal variation is obvious, showing a bimodal double dip type, low in the morning, at noon and in the evening, but high during the rest of the daytime. (4) In summer, PM2.5 concentrations of the measured plots indicate more significant difference, but no significant difference in winter, and PM2.5 concentrations in winter are higher than in summer. (5) The average of NAI concentration of the measured plots shows no significant difference in summer and winter seasons, with CI index being close to the rating of D, which belongs to allow air cleanliness. Meanwhile, the NAI average concentration of the open square is significantly lower than the three different types of green spaces under investigation and its CI index is also the lowest, with the rating of E, indicating that air cleanliness belongs to heavy pollution. Therefore, the conclusions can be drawn as follows, (1) Reasonable layout of green space can improve the air NAI concentration and air quality. (2) Reasonable layout of green space can reduce particle pollution. (3) A significant negative correlation is revealed between NAI concentration and PM2.5 concentration. (4) NAI concentration is shown to have a significant negative correlation with relative humidity, a significant positive correlation with wind speed, and a unclear relationship with the temperature relationship. Based on these conclusions, the paper further proposes to carry out real-time monitor on PM2.5 concentration and NAI concentration and to analyze the results for the relationship between them. It also suggests that the urban green space with different underlying surface structure should be further studied in different seasons and under different weather conditions, in order to ensure the urban green space is conducive to the physical and mental health of the residents and suitable for recreational sports.
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