北京城市森林空气负离子浓度对温度的响应

Responses of negative air ion concentration to temperature in urban forests of Beijing

为掌握城市森林中空气负离子(NAI)浓度对温度变化的响应特征,以北京地区的4个城市森林公园为研究对象,包括北京朝阳公园(中心城区)、南海子郊野公园(近郊湿地区)、西山国家森林公园(近郊浅山林区)和松山国家级自然保护区(远郊山地林区),利用设置的森林生态环境监测站NAI监测仪和自动气象站等连续动态数据,分析2017—2020年NAI浓度随温度变化响应特征。结果表明:2017—2020年各季节的中心城区NAI浓度与温度小时变化呈负相关,14:00—15:00 NAI浓度和温度分别达到最低值和最高值;近郊浅山林区和近郊湿地区的NAI浓度与温度在春、秋、冬三季小时变化呈正相关,夏季呈负相关;在月变化尺度上城市森林各区域NAI浓度与温度均呈正相关,但远郊山地森林区NAI浓度对温度的响应有滞后性;年尺度上NAI浓度与温度呈显著正相关(P<0.01);2020年温度在0~10℃时,与近郊浅山林区NAI浓度负相关强度最强(r=-0.441);10~20℃时,与近郊浅山林区NAI浓度呈极显著负相关(r=-0.253),与远郊山地林区NAI浓度呈正相关;温度介于20~30℃,与近郊湿地区和远郊山地林区NAI浓度均呈极显著负相关;2020年不同城市森林区域NAI浓度与其他气象因素(风速、太阳辐射)的相关性具有明显季节差异;春季近郊湿地区NAI浓度与太阳辐射呈显著正相关;夏季近郊浅山林区NAI浓度与风速呈负相关,近郊浅山林区和远郊山地森林区NAI浓度与太阳辐射分别呈负相关、正相关;秋季远郊山地森林区NAI浓度与太阳辐射呈显著正相关;冬季中心城区和远郊山地森林区NAI浓度与太阳辐射分别呈显著正相关和负相关。

To clarify the responses of negative air ion(NAI)concentration in urban forests to temperature changes,four urban forest parks in Beijing were used as the research objects,including Beijing Chaoyang Park(central ur⁃ban area),Nanhaizi Country Park(suburban wetland area),Xishan National Forest Park(suburban shallow mountain forest area),and Songshan National Nature Reserve(outer suburban mountain forest area).The respon⁃ses of NAI concentration to temperature during 2017-2020 were analyzed using continuous dynamic observation da⁃ta from NAI monitors and automatic weather stations in forest ecological environment monitoring stations.The results showed that NAI concentration in the central urban area was negatively correlated with the changes of hourly tem⁃perature in each season during the four years,with NAI concentration and temperature reaching the lowest and highest values at 14:00-15:00,respectively.In suburban shallow mountain forest area and suburban wetland area,there was a positive correlation between NAI concentration and temperature in spring,autumn,and winter,but a negative correlation between NAI concentration and temperature in summer.At the month scale,NAI concentration in each urban forest area was positively correlated with temperature,but the response of NAI concentration to tem⁃perature in the outer suburban mountain forest area had a hysteresis.At the annual scale,NAI concentration was significantly positively correlated with temperature(P<0.01).In 2020,when temperature was 0-10℃,the nega⁃tive correlation between NAI concentration and temperature in the suburban shallow mountain forest area was the strongest(r=-0.441).At 10-20℃,there was a very significant negative correlation between NAI concentration and temperature in the suburban shallow mountain forest area(r=-0.253),while a positive correlation in the outer suburban mountain forest area.When temperature was between 20-30℃,there was a significant negative correla⁃tion between NAI concentration and temperature in the suburban wetland area and the outer suburban mountain for⁃est area.The correlations between NAI concentration and other meteorological factors(wind speed and solar radia⁃tion)in different urban forest areas in 2020 showed seasonal variations.In spring,the NAI concentration in the suburban wetland area was significantly positively correlated with solar radiation.In summer,there was a negative correlation between NAI concentration and wind speed in the suburban shallow mountain forest area,and a negative and positive correlation between NAI concentration and solar radiation in the suburban shallow mountain forest area and the outer suburban mountain forest area.In autumn,NAI concentration was significantly positively correlated with solar radiation in the outer suburban mountain forest area.In winter,NAI concentration was significantly posi⁃tively correlated with solar radiation in the central urban area and negatively correlated with solar radiation in the outer suburban mountain forest area.