胶州湾河口湿地秋冬季N_2O气体排放通量特征

Characteristics of N_2O Flux in Estuary Wetland of Jiaozhou Bay in Autumn and Winter

2009年9月～2010年2月,利用静态箱-气相色谱法对秋冬季胶州湾大沽河口受潮汐影响的芦苇(Phrag-mites australis)湿地和潮上带常年无积水杂草湿地N2O排放通量特征进行了研究。研究表明:两类湿地N2O排放和吸收具有明显的昼夜变化规律。白天N2O排放高峰出现在12时左右,夜间高峰出现在21时左右,最低值出现在凌晨6时左右。芦苇湿地和杂草湿地秋冬季的最高值分别为151.1μg/(m2.h)、29.3μg/(m2.h),最低值分别为-128.9μg/(m2.h)、-21.5μg/(m2.h)。芦苇湿地秋冬季夜间N2O排放量高于白天,分别是白天的1.54倍和2.09倍;杂草湿地秋季N2O排放通量白天高于夜间,冬季则夜间高于白天且以吸收为主。在对芦苇湿地和杂草湿地进行监测的6个月份中11月排放量最高,排放量分别为42.42 mg/m2、6.89 mg/m2,芦苇湿地N2O排放量普遍高于杂草湿地。芦苇湿地秋、冬季的排放通量分别为56.32 mg/m2、63.38 mg/m2,杂草湿地秋、冬季的排放通量分别为10.45 mg/m2、3.08 mg/m2,芦苇湿地高于杂草湿地,分别是杂草湿地的5.39倍、20.58倍,主要是两类湿地不同的水文特征和不同的植被种类造成的。杂草湿地秋冬季N2O排放通量与5 cm地温、10cm地温呈显著相关关系(P<0.05),芦苇湿地则相关不显著,主要原因是芦苇湿地N2O排放量除了受温度影响,由潮汐引起的干湿交替过程也在很大程度上影响N2O排放和吸收。胶州湾大沽河河口受潮汐影响芦苇湿地和常年无积水的杂草湿地秋冬季均为大气N2O的"源"。

Characteristics of N2O flux in Phragrmites australis wetland affected by tides and weeds wetland without flooding perennial in the Dagu river estuary of Jiaozhou Bay in autumn and winter were observed using a static chamber and gas chromatograph technique from September 2009 to February 2010.N2O emission and absorption of the two types of wetlands have a significant diurnal variation.Day maximums occurred at 12 o＇clock and 21 o＇clock,and the minimum value were usually at about 6 o＇clock in the morning.The maximum values in Phragrmites australis wetland and weeds wetland were 151.1μg/（m2·h）,29.3μg/（m2·h） and the minimum values were-128.9μg/（m2·h） and-21.5μg/（m2·h）,respectively.N2O flux in Phragrmites australis wetland in autumn and winter during the day time was 1.54 and 2.09 times as much as that in the night,respectively.And there were more N2O fluxes from weeds wetland in the day than during the night in autumn,just the opposite for winter.The highest monthly emissions of N2O in Phragrmites australis wetland and weeds wetland were 42.42 mg/m2,6.89 mg/m2 and they were observed in November.Monthly N2O fluxes in Phragrmites australis wetland were more than weeds wetland.Seasonal N2O emissions in autumn and winter were 56.32 mg/m2and 63.38 mg/m2 in Phragrmites australis wetland,and 10.45 mg/m2 and 3.08 mg/m2 in weeds wetland,respectively.N2O flux from weeds wetland in autumn and winter was 5.39 and 20.58 times as much as that from Phragrmites australis wetland which caused by different hydrologic characteristics of wetlands and the different types of vegetation.Further analysis indicated that N2O fluxes in weeds wetland in autumn and winter were significantly positively correlated with 5cm,10cm ground temperature（P0.05）.The relation between N2O fluxes in Phragrmites australis wetland and 5cm,10cm ground temperature was not significantly,N2O emission and absorption in Phragrmites australis wetland was influenced largely by the tides.In addition to affected by temperature at monitoring sites,the process of alternating wet and dry,water level,salinity and tidal effected the emissions and absorption of N2O greatly.In autumn and winter,Phragrmites australis wetland and weeds wetland in the Dagu river estuary of Jiaozhou Bay were the ＂source＂of atmospheric N2O.