持续性降水气象条件下土壤/大气间汞通量特征

摘要

为研究自然条件下地表大气间汞交换通量特征及其影响因素,2012年4月22～25日在位于松花江上游的夹皮沟金矿,使用动态通量箱法(dynamic flux chamber,DFC)与汞分析仪(LUMEX Zeeman RA915+)联用技术测定了在持续性降雨气象条件控制下矿区土壤大气间汞交换通量,同步测定了近地面垂向0～150cm范围内大气汞浓度以及太阳辐射强度和大气温湿度,并分析了汞交换通量与降水条件下气象因子间相关关系.结果表明:在持续性降雨条件控制下,地表大气间的汞交换通量表现为沉降与释放过程连续交替出现特征,这与晴朗天气条件下日型汞通量单峰结构明显不同.降水间歇期土壤大气间汞交换通量在坡耕农田采样点依次为(-2.08±6.11)、(-6.16±33.57)、(-3.20±8.64)和(5.06±18.80)ng(m2-h);在谷底漫滩采样点依次为(-5.21+6.42)、(3.87±28.12)、(-11.87±14.10)和(-9.44+ 12.23)ng/(m2·h).在局地范围内,地形条件差异影响不同地表和近地面大气系统能量收支,并使近地面大气汞浓度和气象因子发生变化,进而影响地表大气间汞交换通量过程和水平.持续性降水条件下,地表和大气间汞交换通量与太阳辐射强度和大气湿度间具有较为明显的正线性相关关系,与大气汞浓度和大气温度间无明显线性相关关系.%At the Jiapigou gold mine of the Songhua River upstream from April 22~25, 2012, the combination technique of the dynamic flux chamber, DFC and the LUMEX Zeeman RA915+ had been used to measure mercury exchange flux between soil and air under the control of durative precipitation. Moreover, the air mercury concentrations in the range of near-surface vertical direction 0~150 cm, solar irradiation intensity, air temperature and humidity had been determined synchronously. Furthermore, the relationships among mercury exchange flux and meteorology factors under the control of precipitation had been analyzed to research the features and its influencing factors in the natural conditions. The results show that under the control of durative precipitation, mercury exchange flux between the earth surface and air showed the features of the process of deposit and release continuous interleave appeared, it is obviously different from day type mercury flux's single summit structure under a fair weather condition. In precipitation intermission, mercury exchange flux between soil and air at slope farmland sampling site were (-2.08±6.11), (-6.16±33.57), (-3.20±8.64) and (5.06±18.80)ng/(m2·h); on the fioodplain of valley bottom sample site were (-5.21±6.42), (3.87±28.12), (-11.87±14.10) and (-9.44±12.23) ng/(m2·h).In the range of partly narrow region, the difference of terrain conditions affected energy budget of different earth's surface and near-surface air system, and made near-surface air mercury concentrations and meteorology factors changed, then affected mercury flux's process and level. Under the durative precipitation, mercury flux between earth's surface and air had obviously positive linear relation with solar irradiation intensity and air humidity, and it doesn't had obviously linear relation with air mercury concentrations and air temperature.