中國空氣中缺少灰塵反而使污染更嚴重?大綱

Airborne dust is normally seen as an environmental problem, but the lack of it is making air pollution over China considerably worse.

雖然空氣中的灰塵通常會被視爲一個環境問題，但缺乏灰塵反而會對中國的空氣污染造成相當嚴重的影響。

A new study suggests less dust means more solar radiation hits the land surface, which reduces wind speed. That lack of wind in turn leads to an accumulation of air pollution over heavily populated parts of China.

一項最新研究表明，較少的灰塵意味着更多的太陽輻射到達地面，這降低了風速。而風力不足會轉而導致中國人口稠密地區空氣污染的積聚。

The researchers found that reduced dust levels cause a 13% increase in human-made pollution in the region.

研究人員發現，由於空氣中灰塵減少，導致人爲因素引發的空氣污染上升了13%。

Hundreds of millions of people across China continue to be impacted by air pollution from factories and coal-fired power plants. Studies suggest that the dirty air contributes to 1.6 million deaths a year, about 17% of all mortalities.

全國數以萬計的人們將繼續受到工廠和燃煤電廠所造成的空氣污染的影響。研究指出，中國每年有160萬人死於污濁空氣引發的疾病，約佔死亡人口總數的17%。

But this new research says that the human-induced pollution is being made worse or better by naturally occurring dust that blows in from the Gobi desert.

但這項新的研究表明，戈壁的風沙對人爲因素造成的空氣污染可以起到調節作用。

Using models to simulate 150 years of wind and dust patterns in the region, the researchers found that the dust deflects significant amounts of sunlight.

通過模擬這一地區150年以來颳風以及灰塵樣本進行分析，研究人員發現，灰塵對陽光能起到顯著的散射作用。

Differences in the temperatures between land and sea cause the winds to blow. Without the dust, the land warms up more and that changes the temperature differential with the sea leading to weaker breezes - and more air pollution.

風的形成來自海洋和陸地之間的溫差。如果沒有灰塵，地面的溫度就會更高，從而改變了陸地和海洋溫差的比值，並導致了風力減弱，空氣污染就更嚴重了。

"There are two dust sources. One is the Gobi and the other is the highlands of north-west China, but we found the Gobi had much more influence," said lead author Yang Yang, from the Pacific Northwest National Laboratory in Washington State, US.

來自美國華盛頓州太平洋西北國家實驗室、該研究的首席作者楊陽表示：“灰塵來自兩個地方。一個是戈壁、另一個是中國西北部的高原，但我們發現戈壁施加的影響更大。”

"Less dust in the atmosphere causes more solar radiation to reach the surface. It weakens the temperature difference between the land and the sea and impacts the circulation of the winds and causes a stagnation over eastern China and that causes an accumulation of air pollution."

“大氣中由於缺乏灰塵，導致地面接收到更多陽光輻射，弱化了陸地和海洋的溫差，並對氣流循環產生影響。由此，中國東部地區的空氣出現停滯狀態，從而導致空氣污染的積聚。”