中亚热带针阔混交林土壤-大气界面释汞通量研究

为了揭示不同气候条件下森林与大气间汞交换的规律,应用动力学通量箱与Lumex RA 915+测汞仪联用技术,选择重庆缙云山国家级自然保护区为研究地点,于2011年4月~2012年3月对针阔混交林土/气界面释汞通量进行了为期1 a的连续监测,并考察了各环境因子对土壤释汞通量的影响.结果表明,缙云山针阔混交林林地土壤年平均释汞通量值为(16.82±6.70)ng·(m2·h)-1,明显高于欧美国家自然背景区;受光照、温度、相对湿度等气象因素以及亚热带地区森林植被生长变化规律影响,缙云山地区林地土壤释汞通量存在显著的季节性差异,暖季林地土壤释汞通量(22.23±13.19)ng·(m2·h)-1]明显高于冷季(6.01±4.05)ng·(m2·h)-1];通径分析结果表明林地土壤释汞通量的日变化特征和1 d中光照强度变化有密切关系,土温、气温和相对湿度与土壤释汞通量之间的显著相关关系可能是光照强度与土壤释汞通量相关关系的表象.

Mercury Fluxes from Conifer-Broadleaf Forested Field in Central Subtropical Forest Zone

Total gaseous mercury fluxes of forested field soils in the subtropical forest zones, Chongqing, Southwestern China were continually monitored from April 2011 to March 2012 to provide insights into the characteristics of gaseous mercury flux with conifer-broadleaf forest covers. Samples were collected from surfaces of forest fields as the most representative terrestrial surfaces in Jinyun Mountain. Simultaneously, meteorological parameters at the soil level relating to GEM fluxes, such as soil temperature, air humidity, and solar radiation were analyzed, and variations of atmospheric GEM concentration were examined. The results showed that annual averaged fluxes from soils in the forest and open-air site were (16.82±6.70) ng·(m²·h)^-1, which was significantly higher than that in the natural background area. Moreover, there was a clear seasonal variation on the forest field. In growing season, the average mercury flux was (22.23±13.19) ng·(m²·h)^-1, while in dormant season the value was (6.01±4.05) ng·(m²·h)^-1. Diurnal variation characteristics of mercury fluxes were closely related to solar radiation on the forest field. Mercury fluxes of the soils were significantly correlated with soil temperature, air temperature and relative humidity, which may be caused by the relationship between solar radiation intensity and mercury emission fluxes from soils.