Asian Dust

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Dust clouds leaving mainland China and traveling toward Korea and Japan.
Dust clouds leaving mainland China and traveling toward Korea and Japan.

Asian Dust (also yellow dust, yellow sand, yellow wind, Korean dust or China dust storms) is a seasonal meteorological phenomenon which affects much of East Asia sporadically during the springtime months. The dust originates in the deserts of Mongolia and northern China and Kazakhstan where high-speed surface winds and intense dust storms kick up dense clouds of fine, dry soil particles. These clouds are then carried eastward by prevailing winds and pass over China, North and South Korea, and Japan, as well as parts of the Russian Far East. Sometimes, the airborne particulates are carried much further, in significant concentrations which affect air quality as far east as the United States.

In the last decade or so, it has become a serious problem due to the increase of industrial pollutants contained in the dust and intensified desertification in China causing longer and more frequent occurrences, as well as in the last few decades when the Aral Sea of Kazakhstan started drying up due to a failed Soviet agricultural scheme.

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[edit] Pollutants

Sulphur (an acid rain component), soot, ash, carbon monoxide, and other toxic pollutants including heavy metals (such as mercury, cadmium, chromium, arsenic, lead, zinc, copper) and other carcinogens, often accompany the dust storms, as well as viruses, bacteria, fungi, pesticides, antibiotics, asbestos, herbicides, plastic ingredients, combustion products as well as hormone mimicking phthalates. Though scientists have known that intercontinental dust plumes can ferry bacteria and viruses, "most people had assumed that the [sun's] ultraviolet light would sterilize these clouds," says microbiologist Dale W. Griffin, also with the USGS in St. Petersburg. "We now find that isn't true." [1]

[edit] Effects

Dust deposition in Beijing during the 2006 season.
Dust deposition in Beijing during the 2006 season.

Areas affected by the dust experience decreased visibility and the dust is known to cause a variety of health problems, not limited to sore throat and asthma in otherwise healthy people. Often, people are advised to avoid or minimize outdoor activities, depending on severity of storms. For those already with asthma or respiratory infections, it can be fatal. The dust has been shown to increase the daily mortality rate in one affected region by 1.7%.

Although sand itself is not necessarily harmful to soil, due to sulphur emissions and the resulting acid rain, the storms also destroy farmland by degrading the soil, and deposits of ash and soot and heavy metals as well as potentially dangerous biomatter blanket the ground with contaminants including croplands, aquifers, etc. The dust storms also affect wildlife particularly hard, destroying crops, habitat, and toxic metals interfering with reproduction. Coral are hit particularly hard. Toxic metals progagate up the food chain, from fish to higher mammals. Air visibility is reduced, including canceled flights, ground travel, outdoor activities, and can be correlated to significant loss of economic activity. Japan has reported washed clothes stained yellow.

Korea Times has reported it costing 3 million won, 6000 gallons of water, and 6 hours to simply clean one jumbo jet.[1]

[edit] Severity

Asian Dust obscures the sun over Aizu-Wakamatsu, Japan on April 2nd, 2007
Asian Dust obscures the sun over Aizu-Wakamatsu, Japan on April 2nd, 2007

Shanghai on April 3, 2007 recorded an air quality index of 500. [2], in the US, a 300 is considered "Hazardous" and anything over 200 is "Unhealthful". 2007 so far seems to be the worst on record.

Desertification has intensified in China, as 1,740,000 km² of land are "dry", it disrupts the lives of 400 million people and causes direct economic losses of 54 billion yuan ($7 billion) a year, SFA figures show.[3] These figures probably vastly underestimate, as they just take into account direct effects, without including medical, pollution, and other secondary effects, as well as effects to neighboring nations.

Global warming as well as El Nino play a role in Asian dust storms, because ice sheets that form in winter can keep dust from sweeping off the land.

[edit] Mitigation

In recent years, South Korea and the People's Republic of China have participated in reforestation efforts in the source region. However, this has not affected the problem in any significant way. In April 2006, South Korean meteorologists reported the worst yellow dust storm in four years.[2] Japan has donated money, equipment, and knowhow to install sulfur filters on coal plants in China. Despite this, a very low percentage of plants have sulfur filters installed.

China also has taken steps, with international support, to plant trees in desert areas, including a claim of 12 billion trees planted. However, the winds are so strong in some places that the trees simply topple or are buried in sand.

In 2007, South Korea sent several thousand trees to help block the migration of the yellow dust. These trees, however, were planted only by highways, because the People's Republic of China stated to South Korea that they could receive the trees but that they would decide where the trees would be planted.

[edit] Local names

Asian dust is known locally by various names, each of which means "yellow dust" or "yellow sand":

  • Huángshā (Simplified: 黄砂; Traditional: 黃砂) in Chinese
  • Kōsa (黄砂) in Japanese
  • Hwangsa (황사, 黃沙/黃砂) in Korean
  • Hoàng sa (黃砂) or bão cát vàng in Vietnamese

[edit] Composition

An analysis of Asian Dust clouds conducted in China in 2001 showed them to contain high concentrations of silicon (24-32%), aluminum (5.9-7.4%), calcium (6.2-12%), and iron, numerous toxic substances were also present, as it is thought that heavier materials (such as poisonous mercury and cadmium from coal burning) settle out of the clouds closer to the origin.

However, Sarah O'Hara of the University of Nottingham in England, writing for the Lancet says that this doesn't mean that the effects are worse closer to the source. People further from the source of the dust are more often exposed to nearly invisible, fine dust particles that they can unknowingly inhale deep into their lungs, as coarse dust is too big to be deeply inhaled.[4] After inhalation, it can cause long term scarring of lung tissue as well as induce cancer and lung disease.

An American study analyzing the composition of dust events over Colorado also points to the presence of carbon monoxide, possibly incorporated in the clouds as they passed over industrialized regions of Asia.

[edit] Historical reports

Some of the earliest written records of dust storm activity are recorded in the ancient Chinese literature (Goudie and Middleton, The changing frequency of dust storms through time, Climate Change 20:197-225 1992). It is believed that the earliest Chinese dust storm record was found in the Zhu Shu Ji Nian (Chinese: 竹书纪年; English: the Bamboo Annals). The record said: in the fifth year of Di Xin (1150 BC, Di xin was the Era Name of the King Di Xin of Shang Dynasty, it rained dust at Bo (Bo is a place in Henan Province in China)(in Chinese: 帝辛五年，雨土于亳).

The first known record of an Asian Dust event in Korea was in 174 CE during the Silla Dynasty.[3] The dust was known as "Woo-To (雨土)" and was believed at the time to be the result of an angry god sending down dust instead of rain or snow.

Specific records referring to Asian Dust events in Korea also exist from the Baekje, Goguryeo, and Joseon periods.

[edit] References

  1. ^ Ill Winds: Science News Online, Oct. 6, 2001
  2. ^ South Korea chokes on "yellow dust". Reuters World News (2006-04-10). Retrieved on 2006-04-10.
  3. ^ For further details, see for example the article by Youngsin Chun and Soon-Ung Park, From Historical Records to Early Warning System of Asian Dust (Hwangsa) in Korea (it also contains a bibliography of historical sources about the subject).

[edit] See also

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[edit] External links