Distinction Between sea salt and lake salt resources
(1) Characteristics of sea salt resources
The surface-layer salinities of the offshore waters of China show a distribution regularity: low in near-shore zones, high in open sea areas and even higher in Kurushio zones, and have a close relationship with seasons: high in winter and low in summer. In winter, the surface-layer seawater salinities average 31.5¡ë in the Bohai Sea, 34¡ë in its central part and less than 26¡ë in its coastal zone; they are in the range of 31¡ë~32¡ë in the northern part of the Yellow Sea and 31.5¡ë~32.5¡ë in the southern part; they are 33¡ë~34¡ë in the most part of the East China Sea, lower than 20¡ë in the area of the Yangtze River estuary, and 34.5¡ë in the zone the Kuroshio flows through. In summer, they average 25¡ë~30¡ë in the Bohai Sea and 30¡ë~32¡ë in the Yellow Sea, and are the lowest, down to below 5¡ë, at the Yangtze River estuary but remain to be around 34¡ë in the Kuroshio zone of the East China Sea. The seawater salinities along the coast of China vary in the range of 26.0¡ë~31.0¡ë in the Bohai and Yellow Seas, 24.0¡ë~32.0¡ë in the East China Sea and 27.0¡ë~34.0¡ë in the South China Sea, and they are very low in all estuary areas.
China’s coastline consists of 3 types of coasts. The first type is plain coasts, i.e., the continental coasts of the Bohai and Yellow Seas distributed to the north of the Hangzhou Bay. They are mostly made up of enormously thick but loose sandy or silty sediments, belonging to the ‘puddly coast’, and are favorable for constructing large and medium-sized saltfields. The second type is embayed coasts, which are mainly distributed along the East China Sea’s continental coasts of Fujian and Zhejiang Provinces to the south of the Hangzhou Bay. They are mostly composed of bedrocks and therefore are also called ‘bedrock coasts’. Coasts of this type are characterized by indented fjords, steep slopes and great water depths but along them there exist plain type coasts of small sizes in river-mouth areas which are good for building medium-sized and small saltfields. The third type is biogenic coasts, which may be subdivided into two subtypes: coral-reef coasts and mangrove coasts. The coasts of this type are distributed along the Taiwan Straits and South China Sea’s coasts of southern Fujian, Taiwan, Guangdong, Guangxi and Hainan provinces and the South China Sea Islands. Along the coastal zones of this type there occur plain-type coasts where it is possible to construct salterns.As the professional manufacturer of complete sets of mining machinery, such as impact crusher,ball mill, Henan Hongxing is always doing the best in products and service.limestone rotary kiln:http://www.hxjq-crusher.com/23.html.ore separating line:http://www.hxjqchina.com/.
The sea-salt producing region of China is divided into two zones: northern and southe-rn. The northern one is the principal sea salt zone, which consists of the sea salt producing areas along the coastal zones of Liaoning, Hebei, Tianjin, Shandong and Jiangsu to the north of the Yangtze River. This zone has an annual precipitation of about 500~900 mm, which is concentrated in June-August, and an annual evaporation of about 1,500~1,800 mm. The salt production season of the northern zone consists of the spring sun-drying period and the autumn sun-drying period. The southern sea salt zone covers the coastal areas of Zhejiang, Fujian, Guangdong, Guangxi, Hainan and Taiwan to the south of the Yangtze River. The southern zone is characterized by high air temperature, plentiful precipitation and great evaporation. In this zone, the method of evaporating the seawater in the sun to make salt in consecutive fine days is adopted and the salt production can be carried out all the year round, but due to the great difference in precipitation, evaporation and climatic condition the seasonal sun-drying salt production periods also differ slightly from area to area (Table 4.8.2).
Precipitation, evaporation and salt production peak season of the sea-salt producing region
(2) Characteristics of lake salt mineral resources
The lake salt mineral resources of China mainly occur in the saline lakes scattered all over the arid-semiarid zones in the western part of the country. The salt deposits were formed in the Quaternary and commonly have not experienced any exogenetic geological process. Salt deposits may occur in the state of solid, liquid and solid-liquid phases. When subjected to the lixiviation by surface water, groundwater and atmospheric precipitation, the solid-phase salt bodies may change to brine (liquig phase); the saline lake brine may gradually get concentrated and crystallized to give rise to solid-phase salt bodies. Such a solid-liquid transformation is a major characteristic feature of lake salt deposits.
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