Baumann A, Schimmack W, Steindl H, Bunzl K
Institut für Strahlenschutz, GSF-Forschungszentrum für Umwelt und Gesundheit, Neuherberg, Germany.
Radiat Environ Biophys. 1996 Aug;35(3):229-33. doi: 10.1007/s004110050034.
The effect of soil sterilization by chloroform fumigation on the release of fallout radiocesium incorporated in the fungal biomass of the organic layer of two forest soils was investigated by applying a sequential extraction procedure for radiocesium. The amount of the biomass in all soil samples was estimated by determination of the dissolved organic carbon (DOC) before and after fumigation, and qualitatively also by the ergosterol test. The five fractions obtained by sequential extraction (modified Tessier procedure) were: (I) easily exchangeable, (II) bound to oxides, (III) bound to organic matter, (IV) persistently bound, (V) residual. For the samples from the soil under spruce trees, no significant effects were apparent in any of these five fractions as a result of chloroform fumigation, indicating that the amount of radiocesium in the biomass of this soil was obviously negligibly small compared with the radiocesium associated with other soil constituents. The results obtained for the soil samples from the beech stand, however, reveal that the destruction of the biomass by chloroform fumigation modified considerably the extent of the association (i.e., binding) of radiocesium with the various other soil constituents (especially the clay minerals). As a result of this rapid redistribution of radiocesium released by the fungal biomass, it is not possible, in general, to attribute the observed increase of radiocesium in fraction I (easily exchangeable) after soil sterilization quantitatively to radiocesium released by the biomass. A reliable method to determine the amount of radiocesium incorporated in the fungal biomass of the soil samples which also contain clay minerals has, therefore, still to be developed.
通过对放射性铯采用连续提取程序，研究了用氯仿熏蒸进行土壤灭菌对两种森林土壤有机层真菌生物量中所含沉降放射性铯释放的影响。通过测定熏蒸前后的溶解有机碳（DOC）来估算所有土壤样品中的生物量，并且还通过麦角甾醇测试进行定性估算。通过连续提取（改良的 Tessier 程序）得到的五个部分为：（I）易交换的，（II）与氧化物结合的，（III）与有机物结合的，（IV）持久结合的，（V）残留的。对于云杉林下土壤的样品，氯仿熏蒸后这五个部分中的任何一个都没有明显的显著影响，这表明与其他土壤成分相关的放射性铯相比，该土壤生物量中的放射性铯含量显然小到可以忽略不计。然而，从山毛榉林分土壤样品获得的结果表明，氯仿熏蒸对生物量的破坏极大地改变了放射性铯与其他各种土壤成分（尤其是粘土矿物）的结合程度。由于真菌生物量释放的放射性铯迅速重新分布，一般来说，不可能将土壤灭菌后在部分 I（易交换的）中观察到的放射性铯增加量定量归因于生物量释放的放射性铯。因此，仍有待开发一种可靠的方法来测定含有粘土矿物的土壤样品中真菌生物量所含的放射性铯量。
