Dust and Sand Storm On April 5, a strong dust storm hit part of western Inner Mongolia, the southwestern part of Ningxia, and the Hexi Corridor in Gansu. It affected a wide area, and had impacts on cities such as Beijing, Jinan, Nanjing and Hangzhou etc. From April 17 to 19, a Force 6 sand and dust storm occurred in parts of Xianjiang. On May 20, Aalashanmengejina Qi of Inner Mongolia was hit by a second dust and sand storm.
Red Tide In 1998, there were five serious red tide disasters, whose effects were wide-ranging and long lasting. Major damages and losses were caused and new species of red tide appeared. From the middle of September to late October, the biggest red tide in history occurred in Bohai Sea. At its largest, it covered an area 5000 km2 and caused huge damages to aqua-culturing, with direct economic losses reaching 120 million yuan RMB. From mid-March to mid-April, there was a large-scale M.Gymnodinium red tide in the Pearl River Estuary of Guangdong and sea waters near Hongkong. It caused the death of fish and shellfish in large quantities and direct economic losses of more than100 million yuan RMB.
Geological disasters In 1998, 400 large-scale and sudden geological disasters took place in China. As a result, 1573 were killed, 1701 injured and 11 people missing. Direct economic losses amounted to more than 10 billion yuan RMB.

At the beginning of April 1998, the department of meteorology predicted heavy flooding in the Yangtze River basin. Based on early warnings, regions in the area prepared for floods in advance. During the floods, 52 large-scale landslides and mud-rock flows were successfully predicted, thus avoiding the deaths of more than 4000 people.
In 1998, the government of China sent a delegation to take part in the Fourth Meeting of the Parties to the Framework Convention on Climate Change.

In the first half-year of 1998, natural disasters frequently took place in China, including snow disasters, earthquake, dust and sand storm, ice run, windstorm freezing, flooding and other disasters. Up to June 30, all kinds of disasters had made 264 million persons affected by disasters, 158 million persons heavily affected by disasters and 1376 persons dead. Additional, 2630 thousand houses had collapsed, 25200 thousand hectors of crops had been affected, 12470 thousand hectors of crops had been heavily affected and 1988 thousand hectors of crops had produced nothing. The directly economic loss caused by all disasters was 57.5 billion RMB. The disasters had three major characters. Firstly, there were various kinds of disasters and they occurred with high frequency. Secondly, the range that was affected by disasters was wide and the losses were serious. Finally, the flooding was outstanding.

Disasters in the first half-year of 1998 were apparently heavier than that in the same time of 1997. (See table 10)

Earthquake In the first half of 1998, there occurred seven earthquakes above grade 4.6 in China. (See table 11)

The seven earthquakes caused 650,000 persons affected, 49 persons dead, 11,000 persons wound, 164,000 houses collapsed and more than 2 billion yuan (RMB) directly economic losses.

In 1998, basin-wide flooding occurred in the Yangtze River, and this was another such big and wide flooding since 1954. On June 27, the mainstream of the Yangtze River exceeded the warning water level. On July 3, flooding frequently occurred in the middle and upper Yangtze River. All these formed eight flood peaks in the station of Yichang. Due to abnormal weather, rainstorm occurred constantly in basin of Yangtze River resulting in a basin-wide heavy flooding that had great quantity, high water level and long lasting. Economic losses caused directly by the flooding totaled mare than 200 billion RMB. The region that was most heavily affected by the flooding was the Hubei Province where 2971,200 persons were besieged by the flooding, 3001,700 persons were transferred, 1061,700 houses were damaged and 446 persons were dead. 152 courtyards were broken by the mainstream of the Yangtze River and 19.3 million m² of farmland was drowned.

The one reason that caused the flooding was the abnormally more precipitation and the rainstorm weather in the east of Sichuan, the two lakes of the upper Yangtze River and the regions in the middle and lower Yangtze River. In June, precipitation above 500mm concentrated in Hunan, the south of Jiangxi and Anhui and coastal regions in north China, meanwhile, precipitation in the areas along the Yangtze River was about 200~400mm. The average precipitation of the year of 1998 was more than 150% that of 1961~1990 in the corresponding time in Nanjing, Nanchang, Yueyang and Chongqing. In July, precipitation above 500mm concentrated in Wuhan, Jiujiang etc., and there still had large areas with 200~400 precipitation in upper Yangtze River. The average precipitation of this year was about 400% that of 1961~1990 in the corresponding time in areas near Wuhan. Also the average precipitation of this year in the east of Sichuan was 150% that of 1961~1990. On August 1~8, precipitation was still 100~200 in the line from Chongqing to Wuhan.

The other reason for the flooding was that people blindly reclaimed land from lakes and occupied basins in the middle and upper Yangtze River. So that although people living in the flooded areas put up dykes in winter and fought a flood in summer, they still gained nothing in nine years out of ten and they paid great price for existence. Apparently, in order to treat the flooding radically in the Yangtze River, it is necessary to transfer the residents in flooded areas and to turn arable land into lake.

In meteorological observation, the weather phenomena, that sand and dust in the ground was blown to the air resulting in the reduction of horizontal visibility, were divided into three kinds. 1) Floating dust: The weather phenomenon that grit or dirt floated in the air causing horizontal visibility less than 10 km; 2) Raised sand or high blown sand (dust): It was the weather phenomenon that horizontal visibility was 1~10 km; 3) Sand storm: It was the weather phenomenon that strong wind blew dust and sand in the ground into the air and made the air very cloudy, and horizontal visibility was less than 1 km.

Aerosol particles were solid and liquid particles floating in the air, their diameters were 10^-3~10¹. Natural sources of aerosol in the air were sea, soil, biosphere and volcano. Aerosol had important effect on change of climate, formation of cloud, change of visibility, cycle of atmospheric trace compositions and human health.

Sand and dust aerosol in China was resulted from process of wind erosion and wind blowing in desert and arid regions, change of land-use, desertification and urbanization owing to human activities. Additional, changes of climate and features of the earth's surface resulting from natural or artificial factors can change the frequency and intensity of sand and dust storm. Every spring a great quantity of sand and dust aerosol came into the air with sand and dust storm. Then in some background of atmospheric circulation, it can be transported to densely populated areas thousands of kilometers away. Therefore threatened and influenced natural environment that human based on. Moreover, sand and dust aerosol particles with the size of several microns can affect people's respiratory system and imperil people's health.

Now sand and dust aerosol's neutralization function to acid rain in the north of China, formation, distribution of sulfate aerosol and its effect on cycle of trace compositions in the sea all aroused general concern in scientific field