The diurnal and seasonal variations of soil respiration （SR） were studied at a subtropical mangrove wetland in the Jiulong River Estuary from May 2010 to April 2011. SR rates were measured continuously from 08：00 t...The diurnal and seasonal variations of soil respiration （SR） were studied at a subtropical mangrove wetland in the Jiulong River Estuary from May 2010 to April 2011. SR rates were measured continuously from 08：00 to 06：00 local time （24-h time system） on July 8-9 and October 3-4, 2010; and January 15-16 and April 11-12, 2011. Similar patterns in the diurnal variation of SR were observed on October 2-3 and April 11-12, with the maximum values at 14：00 and the minimum at 00：00. However, the diurnal dynamics of SR on July 8-9, 2010 and January 15-16, 2011 showed different patterns, with the maximum values at 08：00-10：00 on above sampling dates and the minimum at 22：00 on July 8 and at 04：00 on January 16. The daily mean values of SR approximated to the values measured at 08：00. SR fluctuated with distinct seasonal patterns. The seasonal variation was characterized by a mono-peak pattern, with the highest rate （6.18 ~mol CO2 m-2 s-1） in July and the lowest rate （0.36 ~tmol CO2 m-2 s-1） in December. The results showed that the variation of SR in mangrove wetland was mainly controlled by soil temperature, and there was no significant correlation between SR and soil water content. It also implied that the model of SR in mangrove wetland should not only consider the effect of soil temperature, but also incorporate other factors, such as water level, precipitation, microbial activity and photosynthesis, which also could affect SR.展开更多
Archaea play an important role in global carbon and nitrogen cycles. Archaeal lipids, such as isoprenoid glycerol diakyl glycerol tetraethers(i GDGTs), are important biomarkers tracing change in archaeal community str...Archaea play an important role in global carbon and nitrogen cycles. Archaeal lipids, such as isoprenoid glycerol diakyl glycerol tetraethers(i GDGTs), are important biomarkers tracing change in archaeal community structure and biogeochemical processes in the natural environments. In this research, the spatial distributions of archaeal lipids in the surface sediments of the Jiulong River(JR) and the Jiulong River estuary(JRE) were examined. GDGT-0(containing zero cyclopentyl ring) and crenarchaeol were the most abundant i GDGTs in the JR and JRE. From the rivers to the estuary, the total i GDGTs, GDGT-0, crenarchaeol and archaeol concentrations showed significant spatial variation; in particular, GDGT-0 and archaeol in the river may be predominantly derived in situ from methanogens, whereas crenarchaeol in the estuary mainly derived in situ from Thaumarchaeota. We inferred that archaeal community was dominated by methanogens in the Jiulong River and by Thaumarchaeota in the Jiulong River estuary, which are consistent with change in archaeal community structure observed in other estuarine environments.展开更多
基金Supported by the National Natural Science Foundation of China(No.41176092)
文摘The diurnal and seasonal variations of soil respiration （SR） were studied at a subtropical mangrove wetland in the Jiulong River Estuary from May 2010 to April 2011. SR rates were measured continuously from 08：00 to 06：00 local time （24-h time system） on July 8-9 and October 3-4, 2010; and January 15-16 and April 11-12, 2011. Similar patterns in the diurnal variation of SR were observed on October 2-3 and April 11-12, with the maximum values at 14：00 and the minimum at 00：00. However, the diurnal dynamics of SR on July 8-9, 2010 and January 15-16, 2011 showed different patterns, with the maximum values at 08：00-10：00 on above sampling dates and the minimum at 22：00 on July 8 and at 04：00 on January 16. The daily mean values of SR approximated to the values measured at 08：00. SR fluctuated with distinct seasonal patterns. The seasonal variation was characterized by a mono-peak pattern, with the highest rate （6.18 ~mol CO2 m-2 s-1） in July and the lowest rate （0.36 ~tmol CO2 m-2 s-1） in December. The results showed that the variation of SR in mangrove wetland was mainly controlled by soil temperature, and there was no significant correlation between SR and soil water content. It also implied that the model of SR in mangrove wetland should not only consider the effect of soil temperature, but also incorporate other factors, such as water level, precipitation, microbial activity and photosynthesis, which also could affect SR.
基金supported by the National Key Basic Research Program of China (Grant No. 2013CB955703)the South China Sea-Deep Program of the National Natural Science Foundation of China (Grant Nos. 91028005 & 91428308)+3 种基金the National Natural Science Foundation of China (Grant Nos. 41276125 & 31470539)the "National Thousand Talents Program" at the State Key Laboratory of Marine Geology of Tongji Universitythe Expenses for Chinese University Basic Researchinterdisciplinary Programs (Grant No. 1350219165)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. IUEQN201307)
文摘Archaea play an important role in global carbon and nitrogen cycles. Archaeal lipids, such as isoprenoid glycerol diakyl glycerol tetraethers(i GDGTs), are important biomarkers tracing change in archaeal community structure and biogeochemical processes in the natural environments. In this research, the spatial distributions of archaeal lipids in the surface sediments of the Jiulong River(JR) and the Jiulong River estuary(JRE) were examined. GDGT-0(containing zero cyclopentyl ring) and crenarchaeol were the most abundant i GDGTs in the JR and JRE. From the rivers to the estuary, the total i GDGTs, GDGT-0, crenarchaeol and archaeol concentrations showed significant spatial variation; in particular, GDGT-0 and archaeol in the river may be predominantly derived in situ from methanogens, whereas crenarchaeol in the estuary mainly derived in situ from Thaumarchaeota. We inferred that archaeal community was dominated by methanogens in the Jiulong River and by Thaumarchaeota in the Jiulong River estuary, which are consistent with change in archaeal community structure observed in other estuarine environments.
