Rhizospheric mobilization of radiocesium in soils
Rhizospheric mobilization of radiocesium in soils
复制标题
土壤中放射性铯的根际动员
DOI：
--
复制
发表时间：
2000
期刊：
影响因子：
--
通讯作者：
A. Cremers
中科院分区：
文献类型：
--
作者：
B. Delvaux;N. Kruyts;A. Cremers
虽然土壤-植物转移是放射性元素进入食物链的第一步，但对其在根际的研究却很少。用无载体Cs-137（+）污染了17个不同土壤类型的47个土壤层，并与黑麦草宏观根际密切接触4 d。根际Cs-137的动员与四苯硼钠可提取Cs-137呈显著正相关（r = 0.94），表明根际K耗竭是碳-137吸收的主要驱动力。土壤中Cs-137的土壤-植物转移因子在0.02 ~ 3.69 g g（-1）之间变化，与土壤中常见的Cs结合特征放射性铯截留电位（RIP）呈显著负相关（r = -0.88）。不同土壤材料间RIP差异较大（13 ~ 4861 mu mol g(-1)），与土壤蛭石含量直接相关（r = 0.70）。我们的研究结果在多种土壤中得到了验证，表明蛭状矿物质和植物根系都是根际中Cs-137（+）的竞争性汇。他们进一步支持，在半自然环境中，许多cs -137污染的土壤可能成为上述直立植被长期污染的潜在来源，因为它们具有低K有效度。
Though soil-plant transfer is the first step by which radiocesium enters the food chain, it has been scarcely studied in the rhizosphere. Forty-seven soil horizons from 17 pedons with widely varying properties were contaminated with carrier-free Cs-137(+) and placed into close contact with an active macroscopic rhizosphere of ryegrass for 4 days. The Cs-137 rhizospheric mobilization was strongly correlated with the sodium tetra phenylboron-extractable Cs-137 (r = 0.94), supporting that K depletion in the rhizosphere is a capital driving force in Cs-137 uptake. The Cs-137 soil-plant transfer factor varied from 0.02 to 3.69 g g(-1) between soil materials and was strongly negatively correlated to the radiocesium interception potential (RIP) (r = -0.88), a common Cs binding characteristic in soil. RIP largely differed between soil materials (13-4861 mu mol g(-1)) and was directly related with the soil vermiculite content (r = 0.70). Our results, validated in a wide variety of soils, show that both vermiculitic minerals and plant roots act as competitive sinks for Cs-137(+) in the rhizosphere. They further support that many Cs-137-polluted soils in semi-natural environments can act as a potential source for long-term contamination of the above standing vegetation because they have low K availability.