Seasonal variation in net benthic C-mineralization in a shallow estuary
Seasonal variation in net benthic C-mineralization in a shallow estuary
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浅河口底栖净碳矿化的季节变化
DOI：
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发表时间：
1993
期刊：
影响因子：
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通讯作者：
B. Lomstein
中科院分区：
文献类型：
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作者：
M. Therkildsen;B. Lomstein
摘要通过测量沉积物对O2的吸收，以及从沉积物到水柱的Σ二氧化碳通量，测量了底栖生物净碳矿化的季节变化。氧摄取量在26~181mmolm−2d−1之间变化，Σ二氧化碳流出量在17~132mmolm−2d−1之间变化。这两个参数都与温度有关，氧摄取量和Σ二氧化碳流出量的Q10分别为2.5和2.0。一年中的大部分时间，Σ的二氧化碳/O2比值在0.8%至1.0%之间变化。而在夏末和秋季，Σ的CO_2/O_2比值小于0.8，这可能是由于累积的还原硫化物的再氧化和碳酸盐的沉淀所致。1990年9月和1991年8月，软体动物的碳酸钙沉积似乎对Σ二氧化碳的外流具有定量上的重要性。在底栖生物和沉淀物微藻分解过程中，Σ/O2比值在4月中旬达到最大值1.3.从全年来看，所有在厌氧矿化过程中还原的氧化剂(如Mn2+、Fe2+、HS−)显然都被O2重新氧化，如年ΣCO_2/O_2比值为0.8时所示。底栖大型动物促进碳矿化，O2吸收和Σ二氧化碳外排速率分别与大型动物生物量呈正相关。沉积物中叶绿素-a+色素含量和C/N比是藻类从水体中沉积和底栖微藻存在的良好指标。沉积物参数包括有机碳、有机氮含量、C/N比、叶绿素a+色素含量等，较好地反映了沉积物矿化速率的季节变化。在有机质输入和底栖生物碳矿化之间存在时间相移，这导致在初级生产力高和/或碳矿化低的时期(春季、深秋、冬季)有机质暂时积累。累积的有机质是在有机质实际供应不足的时期(夏季、初秋)矿化的。
Abstract Seasonal changes in net benthic C-mineralization were measured as sediment O2 uptake, as well as ΣCO2 flux from the sediment to the water column. Oxygen uptake varied between 26 and 181 mmol m−2 d−1 through the year, and ΣCO2 efflux varied between 17 and 132 mmol m−2 d−1. Both parameters were related to temperature, and the Q10 for O2 uptake and ΣCO2 efflux were 2.5 and 2.0, respectively. The ΣCO2/O2 ratio varied between 0.8 and 1.0 during most of the year. The ΣCO2/O2 ratio was, however, less than 0.8 in late summer and autumn, which might be due to reoxidation of accumulated reduced sulfur compounds and carbonate precipitation. Calcium carbonate deposition by molluscs seemed quantitatively important for the ΣCO2 efflux in September 1990 and August 1991. The ΣCO2/O2 ratio reached a maximum of 1.3 in mid-April during decomposition of benthic and sedimented microalgae. On an annual basis, all the oxidants which were reduced during anaerobic mineralization (e.g., Mn2+, Fe2+, HS−), apparently were reoxidized by O2, as illustrated by an annual ΣCO2/O2 ratio of 0.8. Benthic macrofauna stimulated C-mineralization, indicated by a positive relationship between O2 uptake and ΣCO2 efflux rates, respectively, and macrofauna biomass. Sediment chlorophyll-a + pheopigment content and C/N ratio served as good indicators both of algal sedimentation from the water column and of the presence of benthic microalgae. The sediment parameters, including the organic carbon and nitrogen content, C/N ratio, and chlorophyll-a + pheopigment content, clearly reflected the seasonal variation in sediment mineralization rates. There was a temporal phase displacement between input of organic matter and benthic C-mineralization, which resulted in a temporary build up of organic matter during periods with high primary production and/or low C-mineralization (spring, late autumn, winter). The accumulated organic matter was mineralized during periods when the actual supply of organic matter was insufficient (summer, early autumn).