长江口潮滩土壤呼吸季节变化及其影响因素

Seasonal variation of soil respiration and its influence factors in tidal flat of Yangtze Estuary

采用静态箱-气相色谱法,于2007年7月至2008年5月对长江口潮滩土壤呼吸通量进行了观测,同时对潮滩气温、土壤温度、近岸水体盐度等环境参数进行了观测.结果表明,长江口潮滩土壤是大气CO2的排放源.土壤呼吸速率具有明显的季节变化规律,呈单峰形变化,并于7～8月出现排放峰值.气温和各层土壤温度与土壤呼吸速率作用之间具有显著线性关系(p<0.05),表明温度可能是控制长江口潮滩土壤呼吸速率季节变化的主要环境因子,而土壤含水量对土壤呼吸的影响不显著.长江口潮滩土壤呼吸速率的高低顺序为:吴淞口(WSK)>白龙港(BLG)>东海农场(DH)>奉新(FX),呈现出近岸水体年均盐度越高,土壤呼吸速率越低的趋势.总体来说,长江口潮滩土壤呼吸速率季节变化是温度因子以及近岸水体盐度季节变化协同作用的结果.

Soil respiration in the tidal flat of Yangtze Estuary was investigated from July 2007 to May 2008,using a static chamber combined with a gas chromatograph.Environmental factors including air temperature,soil temperature,soil water content and coastal water salinity were also measured during the sampling periods.The results showed that soils from the tidal flat of the Yangtze Estuary were net sources of atmospheric CO2,and soil respiration fluctuated with distinct seasonal patterns.Seasonal variation of soil respiration was characterized by a mono-peak pattern with the highest rate in July through August.Soil respiration was observed to significantly correlate to air temperature and soil temperature,probably indicating that soil respiration at the study area was predominantly controlled by air temperature and soil temperature.In contrast,no significant correlation was found between soil respiration and soil water content.The highest soil respiration rate appeared at Station WSK,followed by BLG,DH and FX.This spatial difference in soil respiration implied that soil respiration rates generally decreased with the increasing water salinity.In conclusion,the seasonal change of soil respiration in the Yangtze Estuary was co-effected mainly by temperature and water salinity.