TURNOVER OF C-14-LABELED ACETATE IN MARINE-SEDIMENTS
TURNOVER OF C-14-LABELED ACETATE IN MARINE-SEDIMENTS
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DOI：
10.1007/bf00394618
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发表时间：
1982-01-01
期刊：
影响因子：
2.4
通讯作者：
BLACKBURN, TH
中科院分区：
文献类型：
--
作者：
CHRISTENSEN, D;BLACKBURN, TH
提出了一种测定沿海海洋沉积物中挥发性脂肪酸（VFA）的方法。在沉积物上部10 cm处发现2-70 nmol的醋酸盐cm-3沉积物。均匀标记14c -乙酸(0.02 nmol, 10-3 .mu。Ci)通过未受干扰的沉积物岩心管内的硅胶塞孔以1至2厘米的间隔注入。利用14c -乙酸盐放射性随孵育时间的半对数曲线确定了周转率常数。14c -乙酸盐分布在至少3个沉积物池中：孔隙水池、被过量乙酸置换的吸附池和未被过量乙酸置换的吸附池。所调查沉积物的速率常数为1.5 ~ 13 h-1。通过循环速率常数和孔隙水中的醋酸盐浓度计算醋酸盐的循环速率。由NH4+周转量和沉积物有机质N:C比值计算的乙酸周转率仅为测定的乙酸周转率的16%。对醋酸酯周转的明显高估很可能是由于对可降解醋酸酯池的高估。凝胶过滤含有14c -醋酸酯的孔隙水表明，含有示踪剂的馏分只有总乙酸的25%。这意味着孔隙水中的大部分醋酸盐对微生物来说是不可用的。这也表明，当添加的14c -乙酸酯被氧化时，在与14c -乙酸酯孵育的孔隙水中所测量的乙酸池没有减少。
A method for the determination of volatile fatty acids (VFA) in coastal marine sediments is presented. In the upper 10 cm of the sediments 2-70 nmol acetate cm-3 sediment was found. Uniformly labeled 14C-acetate (0.02 nmol, 10-3 .mu. ci) was injected at 1- to 2-cm intervals through silicone-stopper holes in the tubing of undisturbed sediment cores. Turnover rate constants were determined from semilogarithmic plots of the 14C-acetate radioactivity vs. the incubation time. The 14C-acetate was distributed in at least 3 sediment pools: a porewater pool, and adsorbed pool which was displaced by excess acetate, and an adsorbed pool which was not displaced by excess acetate. The rate constants ranged from 1.5-13 h-1 in the investigated sediments. The turnover rates of acetate were calculated from the turnover rate constants and the acetate concentrations in the porewater. The rate of acetate turnover calculated from the NH4+ turnover and the N:C ratio of the sediment organic matter was only 16% of the measured rate of acetate turnover. The apparent overestimation of the acetate turnover was most likely due to an overestimation of the degradable acetate pool. A gel filtration of 14C-acetate-containing porewater showed that the fractions which contained the tracer had only 25% of the total acetate. This implied that a large fraction of the acetate in the porewater was unavailable to the microbes. This was also indicated by the fact that the measured acetate pool in porewater incubated with 14C-acetate did not decrease, when the added 14C-acetate was oxidized.