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Needle ice is a phenomenon that occurs when the temperature of the soil is above 0 °C (32 °F) and the surface temperature of the air is below 0 °C (32 °F). The subterranean liquid water is brought to the surface via capillary action, where it freezes and contributes to a growing needle-like ice column.
Contents
- Formation
- Erosion
- Fukushima Power Plant Incident
- Observation in East Tennesse and Vancouver
- Plant Growth
- References
Needle ice requires a flowing form of water underneath the surface, from that point it comes into contact with air that is below freezing. This area of the process usually occurs at night when temperature peaks its low point. From then on, it produces a needle like structure as we know as “Needle Ice”.
The ice needles are typically a few centimetres long. While growing, they may lift or push away small soil particles. On sloped surfaces, needle ice may be a factor contributing to soil creep.
Alternate names for needle ice are "frost pillars" ("Säuleneis" in German), "frost column", "Kammeis" (a German term meaning "comb ice"), "Stängeleis" (another German term referring to the stem-like structures), "shimobashira" (霜柱, a Japanese term meaning frost pillars), or "pipkrake" (from Swedish pipa (tube) and krake (weak, fine), coined in 1907 by Henrik Hesselman).
The similar phenomena of frost flowers and hair ice can occur on living or dead plants, especially on wood.
Formation
In order for needle ice to form there needs to be a process of Ice Segregation, which only occurs in a porous medium when supercooled water freezes into existing ice, growing away from the ice/water interface. As water permeates the ice, it becomes segregated into separate pieces of ice in the form of lenses, ribbons, needles, layers or strands of ice.
Needle ice is commonly found along stream banks or soil terraces. It is also found by gaps around stones and others areas of patterned ground. The variety of soil properties also affects where its found. Places where the soil is much deeper and richer can affect the growth of the ice. Consequently the deeper the soil, the larger the water content allows it to develop. It can be evidently formed anywhere where underground water is exposed to open (freezing) air.
Needle ice is most suitable in soils with a high silt and organic matter content. Needle ice consists of groups of narrow ice slivers that are up to several centimeters long. The largest recorded needle ice was at 10 cm in length.
Needle ice grows up slowly from the moist and water-penetrable soil, and melts gradually in the sun. It can vary in appearance but always shows the consistent growth of ice perpendicular to the land surface. Needle ice looks like a bunch of filamentous crystals, and is in straight or curve shape. It usually forms in the morning when temperature drops below freezing point (0 °C).
Erosion
The emergence of needle ice has been recognized as a geomorphic agent of soil disturbance. The growth of needle ice lifts a detached, frozen soil crust riding on top of the layer of ice. When the crust and the ice melt, the soil surface settles back irregularly. This process is what loosens the soil surface, destroying the cohesion of the soil. Once all of it dries, the wind can just remove the soil particles resulting in erosion. This erosion is most commonly seen on banks, which has a major effect on them. Needle ice tends to move rocks in the soil upwards toward the surface. Then, the soil becomes infertile in those areas.
Fukushima Power Plant Incident
The Fukushima Daiichi nuclear disaster was an explosion of the Fukushima Nuclear Power Plant on March 11, 2011. The disaster was caused by a tsunami that was quickly followed by an earthquake resulting in one of Japan’s largest nuclear damages. The land closest to the plant and nearby areas are contaminated indefinitely until Japan can conceal and remove radio cesium from the area.And one of the major ideas to conceal any further chemical leakage was to build an ice wall within the plant’s building to slow down groundwater spreading. But recent research has shown that the ice wall was proven to be ineffective to the surrounding areas. The reason why, was because of the areas’ soil migration, or chemical adsorption. Because the soil was slow absorb contaminated particles downward into the ground, it remains at the uppermost level of soil, vulnerable to erosion. Making the formation of needle ice, one of the main reason of redistribution of contaminated soil, easier to transfer the contaminated soil to surrounding areas. In addition to the ice wall, the land in the area would receive constant water from the ice, adding to the increase chance in precipitation.
Observation in East Tennesse and Vancouver
The phenomenon of needle ice was observed in East Tennessee. Through the observation, the air temperature was above freezing where it leads to the fact that a form of ice called Pebble ice grew on a few rocks. In fact, the phenomenon has been studied in a climatologic experience at Vancouver, Canada. In this sense, the experiment involves the analysis of the soil surface temperature, net radiation. Therefore, the researchers inform that the growth of needle ice occur during a single freeze-thaw cycle. In addition, the needle ice may become less abundant as the soil surface dried out. The heat released in the conversion of the water into ice truly plays an important role in the process of the growth of needle ice. through the experiment, the formation of needle ice may result from the soil cooling as the conversion of the water into ice releases a heat, and that there are many changes experienced from the soil moisture which are considered to be the main causes of the growth of needle ice.
Plant Growth
Needle ice affects the growth of plants. Seedlings are often heaved to this surface by needle ice. When the ground hardens the stems and roots of the seedling, they are gripped by the soil and then the formation of needle ice is what pushes them up and out the ground. When the needle ice melts, the seedlings do not settle correctly back into the ground causing these seedling to die. Even if the seedlings are partially heaved by the needle ice, they can still die due to root desiccation. Heaving accounts for 95% of all seedlings deaths. Not only does needle ice affect the soil around it but it also kills the vegetation.