Freezing nucleation apparatus puts new slant on study of biological ice nucleators in precipitation
Freezing nucleation apparatus puts new slant on study of biological ice nucleators in precipitation
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DOI：
10.5194/amt-7-129-2014
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发表时间：
2014-01-01
影响因子：
3.8
通讯作者：
Morris, C. E.
中科院分区：
文献类型：
--
作者：
Stopelli, E.;Conen, F.;Morris, C. E.
几十年来，水滴冻结仪器有助于更好地了解生物冰成核及其对云和降水发展的可能影响。然而，目前的文书有其局限性。在冷台上分析的液滴容易蒸发和潜在污染。封闭管的使用为这些问题提供了部分解决方案，但是冻结事件仍然难以被清楚地检测到。在这里，我们提出了一种新的设备，其中冻结在封闭的管是自动检测的光传输变化后，冰的发展，所造成的气泡和晶体刻面的形成，散射光。然后最小化与检测样品的冷冻温度相关的污染和引入偏差的风险。为了说明新设备的性能，我们展示了两个雪样测定的初步结果。在其中一个实验中，我们在+4摄氏度下储存了一个月的时间，反复分析了样品（208管），在此期间，通过在-4摄氏度左右活跃的冰核因子数量的增加，出现了生物冰核活性的证据。在第二次试验中，我们表明越来越多地从沉淀样品中分离单个冰成核剂的可能性，可能确定负责直接在样品中测量的成核活性的颗粒的性质。这两种开创性的方法突出了这种方便的设备，为生物冰成核研究提供新的观点的相关性。
For decades, drop-freezing instruments have contributed to a better understanding of biological ice nucleation and its likely implications for cloud and precipitation development. Yet, current instruments have limitations. Drops analysed on a cold stage are subject to evaporation and potential contamination. The use of closed tubes provides a partial solution to these problems, but freezing events are still difficult to be clearly detected. Here, we present a new apparatus where freezing in closed tubes is detected automatically by a change in light transmission upon ice development, caused by the formation of air bubbles and crystal facets that scatter light. Risks of contamination and introduction of biases linked to detecting the freezing temperature of a sample are then minimized. To illustrate the performance of the new apparatus we show initial results of two assays with snow samples. In one, we repeatedly analysed the sample (208 tubes) over the course of a month with storage at +4 degrees C, during which evidence for biological ice nucleation activity emerged through an increase in the number of ice nucleators active around -4 degrees C. In the second assay, we indicate the possibility of increasingly isolating a single ice nucleator from a precipitation sample, potentially determining the nature of a particle responsible for a nucleation activity measured directly in the sample. These two seminal approaches highlight the relevance of this handy apparatus for providing new points of view in biological ice nucleation research.