亚洲人成网站18禁止中文字幕,国产毛片视频在线看,韩国18禁无码免费网站,国产一级无码视频,偷拍精品视频一区二区三区,国产亚洲成年网址在线观看,国产一区av在线

Xinhua News Agency sources have reported new research revealing that the sandstorms in northern China do not come from the deserts as had been widely believed.

A recent study undertaken by specialists from the Cold and Drought Areas Environment and Engineering Institute of the Chinese Academy of Sciences now points towards the real sources and the underlying causes.

The result of the research shows that average dust content in material making up China's deserts is only some 2.5 percent rising to 12 percent in those areas around the desert edge. Dry farmland has been shown to have some 30 percent with desert-encroached grassland as high as 52 percent. However, the highest dust counts of all have been identified at 63 percent in dry lake basins and dry riverbeds.

Yang Gensheng, a professor at the Cold and Drought Areas Environment and Engineering Institute, said, "Based on these statistics, the desert is not the major source of the material which gives rise to sandstorms and dust-laden atmosphere."

He went on to explain, "Sand-encroached grasslands, dry lake basins and dry riverbeds are in fact what most damage the environment. Over-grazing and over-utilization of groundwater lie at the root cause. These human interventions have led to the present conditions in the sand-encroached grasslands and have caused lakes and rivers to dry up.

This research points the way towards the priority measures necessary. A good cover of vegetation should be encouraged to stabilize and protect the grasslands. Water resources should be conserved. Exploitation on the desert edges should be controlled and steps taken to deal with dust areas which occur within oasis".

According to these experts, it is dust particles with a diameter less than 0.063mm that are the major factor in sandstorms and dust-laden atmosphere. The particle size is particularly important as wind can quickly distribute this type of material over a wide area.

Efforts to reduce sandstorm and dust in the atmosphere need to begin with the prevention of fine dust particles at source. The varied nature of the topography of the country and of the materials which give rise to these adverse weather conditions, mean that there will be no quick and easy answer. However answers must be found for it is not only the environment but also the health of the people that are at risk.

(china.org.cn by Zhang Tingting, July 3, 2002)