太湖水-气界面磷化氢释放通量的观测

Phosphine Emission Fluxes Across the Water-air Interface of Tai Lake

磷化氢是大气中普遍存在的一种痕量气体,它是磷的气相载体,能够在湖泊水体和大气中进行迁移转化,参与磷的生物地球化学循环,从而对湖泊的富营养化造成影响。太湖是典型的磷限制型湖泊,富营养化问题严重,为了弄清磷化氢是太湖水体的源与汇以及其对湖泊富营养化的影响,本文利用静态箱观测法对冬夏两季太湖水-气界面磷化氢释放通量的日变化和季节变化进行观测,利用柱前两次低温冷阱富集-气相色谱/氮磷检测器联用技术对样品进行分析。结果表明,磷化氢(PH3)的释放通量日变化为白天低,晚间高。极大值出现在5:00,极小值出现在11:00～14:00。不同点位间水-气界面磷化氢释放通量在(0.04±0.01)～(3.32±0.13)ng·m-2·h-1之间,夏季PH3释放通量要高于冬季,平均释放通量为(1.34±0.20)ng·m-2·h-1。太湖水体是大气中磷化氢的源。

Phosphine, a ubiquitous trace gas in the atmosphere, acts as a carrier of gasous phosphorus in the P biogeochemical cycle. It can transfer between water body and ambient air and relates to the eutrophication of lakes. In this paper, a seriously eutrophicated and phosphorus restricted lake, Taihu Lake, is chosen to investigate whether it is a possible source and sink of phosphine and the role of phosphine during the eutrophication of Taihu Lake. Stationary box method was used to study the phosphine flux across the water-air interface of Taihu Lake in winter and summer. Samples were collected and measured by GC-NPD equipped with two cryotraps. The phosphine emission flux was found to be higher at night than that at day. The maximum diurnal emission flux of PH3 was at 5：00 am, and the minimum flux at 11：00-14：00 pm. The phosphine emission fluxes varied from （0.04±0.01） to （3.32±0.13）ng·m^-2·h^-1 at the different sampling sites of Taihu Lake. The average flux of phosphine in summer were （1.34±0.20）ng·m^-2·h^-1, higher than those in winter. Taihu Lake is an important source of phosphine to atmosphere.