China has the best air and water.

The city with the best air and water in China should be Sansha City. Sansha has a tropical maritime monsoon climate. Directly exposed to the sun twice a year, the annual total solar radiation is 140 kcal/cm2. It is summer weather all year round, and the heat and temperature are the highest in China, but there are few hot summers due to the adjustment of the ocean. From June to March in 65438, the northeast monsoon prevailed, and from May to September, the southwest monsoon prevailed, with an average wind speed of about 6 meters per second. There are 6-7 typhoons every year on average, with the maximum exceeding 10, of which 70% come from the western Pacific and 30% from the South China Sea itself. July ~ 10 is the typhoon peak season every year. The annual average rainfall is between 1500 ~ 1900 mm, but the time distribution is uneven. The rainy season lasts from 65438+February to May of the following year, and from June to165438+1October, so there are only two seasons in a year, the former is dry season and the latter is rainy season. [26]

hydrology

Sansha sea area is less affected by continental climate and land runoff, and the deep-sea basin has high water depth, salinity, transparency and small seasonal variation of water temperature. It flows to the northeast in summer and southwest in winter, with a velocity of 0. 1 ~ 1.0 knots. The annual average effective wave height of ocean waves is 1 ~ 2m, and the maximum effective wave height is 7.5 ~ 9.5m, ranking first among the four continental marginal seas in China. The average sea surface temperature is between 24℃ and 30℃, the temperature difference between north and south sea water and the annual temperature difference between sea water is about 2 ~ 5℃, and the temperature difference changes from north to south. However, the temperature difference between the surface and bottom of seawater (below 500 meters) is very large, which can be as high as 20℃. The salinity of seawater is between 32 ‰ and 35 ‰. The transparency of seawater is between 20 and 30 meters, which is higher than the other three sea areas in China. 【-Southwest uplift highlands and deep troughs are alternately arranged. From the periphery to the center, there are continental shelf, continental slope and central basin in turn, which are roughly concentric three-layer ring structure. The general features of submarine landforms are: shallow sea continental shelf in the north, west and south, continental slope in the outer edge, and plateaus, seamounts, canyons, troughs and trenches on the continental slope; The east is a narrow island shelf, and the outer edge is adjacent to trenches and troughs; The center is a deep-water basin, and the bottom of the basin is a vast plain dotted with isolated seamounts. The whole South China Sea submarine landform can be divided into nine geomorphological zones, such as northern accumulation shelf zone, northern fault terrace zone, western accumulation-erosion shelf zone, western fault terrace zone, southern accumulation shelf zone, southern divided plateau shelf zone, eastern erosion-accumulation island shelf zone, eastern fault ridge island slope zone and central deep sea plain zone, all of which belong to coral reef landform. [26]

Sansha

Natural resources?

Biological resources

There are thousands of low-grade plant algae rich in carbohydrates, protein, fats, vitamins and minerals in Sansha sea area, which ranks first among the four sea areas in China and is known as "the forest in the sea" and "the undersea grassland". There are many kinds of marine animals, mainly coelenterates, echinoderms, fish, shrimp, shellfish, reptiles, mammals and so on. Among them, coelenterate corals have 1 10 species and 5 subspecies, accounting for more than half of the coral species in China; There are about 2000 kinds of fish, including about 800 kinds of economic fish and more than 200 kinds of high-value fish. Precious aquatic products include pearl oyster, conch, abalone, sea cucumber, sea urchin, lobster, turtle, tortoise shell, sperm whale and so on. The land animals on the island are mainly marine birds, including boobies, herons, seagulls, warships and more than 65,438+10,000.

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aquatic product

Many animals and plants in Sansha tropical ocean have high medicinal value, such as corals, shellfish, algae, etc., and all have many specific metabolites. It can extract anti-cancer drugs such as sun, moon, sponge, shark cartilage and marine snake venom, which is an important medicinal marine resource in China.

The potential catch of fishery resources in the South China Sea is 6.5 million tons to 7 million tons, of which the potential catch in the shallow Hainan shelf area (including Beibu Gulf) with a water depth of 500 meters is about 5 million tons; The potential catch in the southwest waters of Zhongsha Reef Plate is about 6,543,800 tons. The potential catch within the traditional boundary line of China in the south of Nansha is about 300,000 tons. In addition to the above-mentioned sea areas, the South China Sea Interrupted Line also has a deep water area of 6.5438+0.5 million square kilometers, with a potential catch of about 600,000 tons. [26]

mineral resources

There are a lot of valuable minerals in the seabed of the archipelago, including dozens of metallic elements such as iron, manganese, copper, nickel, cobalt, lead and zinc, nonmetallic minerals such as zeolite and coral shell limestone, and hydrothermal deposits, among which manganese nodules and cobalt nodules are abundant, which are seabed minerals with great economic development value.

The salinity of seawater in Sansha sea area is high, with a total salt content of more than 7 billion tons, and the prospect of developing salt industry by using seawater is broad. Seawater also contains more than 80 chemical elements. It is promising to extract elements and chemicals such as potassium, sodium, calcium, magnesium, nickel, uranium, gold, iodine, bromine, carbon, strontium, boron, silicon, hydrogen, oxygen, deuterium, fluorine, heavy water and mirabilite from seawater. [26]

energy resources

The reserve of temperature difference energy in Sansha City can reach 18.99× 1020 Joule per year.