The Bohai Sea, the northernmost offshore of China, is the capital of the People's Republic of ChinaInland Sea, also belonging toInternal waterCategory.coastlineThe total length is about 3800km.It is about 346 kilometers wide from east to west and 550 kilometers long from north to south.It covers an area of about 80000 square kilometers, with an average depth of 18 meters.The Bohai Sea is a nearly closed inland seaLiaodong PeninsulaLaotieshan headland via Miaodao toShandong Peninsula The connection line of Penglai Cape at the north end is separated from the Yellow Sea.The other three sides are surrounded by land. The north, west and south are adjacent to Liaoning, Hebei, Tianjin and Shandong respectively.According to the landform, the Bohai Sea can be divided intoLiaodong Bay、Bohai Bay、Laizhou Bay, Central Shallow Basin andBohai StraitPart 5.[1]
In December 2018, the Ministry of Ecological Environment, the National Development and Reform Commission and the Ministry of Natural Resources jointly issued《Action Plan for Comprehensive Management of Bohai Sea》(hereinafter referred to as the "Action Plan"), which defines the overall requirements, scope and objectives, key tasks and safeguard measures of the comprehensive management of the Bohai Sea, and proposes the timetable and roadmap for the comprehensive management of the Bohai Sea.[4]
According to historical records, during the Western Zhou Dynasty, there was no specific name of the sea area in the Sea of China. All the visible sea areas were called "sea".With the development of economy, the increase of residents, the rise of fisheries and the frequent occurrence of marine disasters in coastal areas, people began to name and distinguish sea areas.
According to historical records, the Bohai Sea was renamed "Bohai",Su QinHe once said that there is Bohai in the north of Qi.Tian Ken once said that the west of Qi is limited by the turbid river, and the north has the benefit of Bohai.The Bohai Sea is also called "Shaohai". Han Feizi records that:Duke Jing of QiYou can swim in Shaohai.Since the Yuan Dynasty, the name of "Bohai Sea" has been used up to now.
Location context
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Geographical location
Geographical location of the Bohai Sea
Bohai Sea, located inChinese MainlandThe northern end of the east is located between 37 ° 07 ′~40 ° 56 ′ N and 117 ° 33 ′~122 ° 08 ′ E. The Bohai Sea is a closed seaInland SeaIn the east, the Yellow Sea is separated from Laotieshan Cape in Liaodong Peninsula to Penglai Cape in the north of Shandong Peninsula via Miao Island.The other three sides are surrounded by land, and the north, west and south sides are respectivelyLiaoning、Hebei、TianjinandShandongThree provinces and one city are adjacent.
The coastline of the Bohai Sea is about 3800km long.It is about 346 kilometers wide from east to west and 550 kilometers long from north to south.It covers an area of about 80000 square kilometers, with an average depth of 18 meters.According to the landform, the Bohai Sea can be divided into five parts: Liaodong Bay, Bohai Bay, Laizhou Bay, Central Shallow Sea Basin and Bohai Strait.[5]
The sea floor of the Bohai Sea is flat, mostly composed of silt andOozeThe terrain inclines from the three bays to the Bohai Strait.The coast is divided into silt and siltationMuddy bank, sandy bank and bedrock bank.Bohai Bay,Yellow River DeltaAnd the north coast of Liaodong BayMuddy coast，Luanhe estuaryThe west coast of the Bohai Sea to the north belongs to sandy coast, and the north coast of Shandong Peninsula andLiaodong PeninsulaThe West Bank is mainlyBedrock coast。
There are many opinions about the boundary between the Bohai Sea and the Yellow SeaLiaodong PeninsulaThe western corner of the old railway and the northern shore of Shandong PeninsulaPenglai headThe line between is the boundary. In this sense, the Bohai Sea covers an area of 77000 square kilometers, with an average depth of 18 meters and a total capacity of only 1730 cubic kilometers.The water along the Bohai Sea is shallow, especially where the river flows only a few meters deep;And the easternLaotieshanThe deepest waterway is 86 meters.
According to the geological and geophysical survey data, the Bohai Sea isNorth China PlatformA part of the North China platform has the same platform type structure as the North China platform.It can be divided into basement andCaprockTwo parts: according to gravity and magnetic survey data and geological data of adjacent areasTanlu fault zoneYingwei fault zone, an extension of Bohai Sea, is divided into east and west parts.The east of the fault zone, including Jiaoliao area, is the high value area of gravity field, and the magnetic force is based on the negative magnetic field, which indicates that the basement in the east of Bohai Sea is similar to Jiaoliao areaCrystalline schistandgneissform.The western half to the west of the fault zone is the main part of the Bohai Sea. The gravity is low and the magnetic force is lowPositive magnetic fieldBackground.This background of low gravity and high magnetic force is similar to the gravity and magnetic field characteristics of Yanshan area in the north and Luxi area in the south.Therefore, it can be inferred that the basement in the western Bohai Sea and the Archean andProterozoicThe crystalline metamorphic basement is the same, which is a set of migmatite and gneiss with deep metamorphism and widespread migmatization,GranuliteArchean group with medium metamorphic degreeMigmatizationUnusualSchist, gneiss, quartziteslate、PhylliteEarly Proterozoic strata.
The study of regional basement structure shows that the tectonic development of the Bohai Sea is quite consistent with that of the North China Platform.Wutai Movement(2.2 billion years ±) resulted in east-west fold, fracture andGranitoidsIntrusion of.Luliang Movement(1.85 billion years ±), making the Lower Proterozoic mainly in NE-NNEE directionFault structureAnd deepened the metamorphic degree of the underlying strata.The Luliang movement finally formed the unified metamorphism of the North China platform including the Bohai SeaCrystalline substrate。
According to the comprehensive geophysical data and drilling revealed data, the caprock in the Bohai Sea can be divided into three structural layers:
1. Lower structural layer
followingPaleozoicMainly marine carbonate rocks, Upper Paleozoic carboniferous——permianThe stratum of marine terrestrial interaction is extremely thin and not widely distributed.
2. Middle structural layer
Bohai Sea during the glacial maximum
yesjurassic period、CretaceousAnd the oldTertiaryThere is slight unconformity between the continental and lacustrine facies strata and the upper and lower structures.Jurassic——Cretaceous systemThere are differences in lithology between the north and the south, with the Shaleitian bulge Laotie waterway as the boundary, and the middle of the north,Basic volcanic rockAnd clastic rock, red sandstone and mudstone andTuffClass.mesozoicSince then, most areas around the Bohai Sea have risen and uplifted, while the Bohai Sea area has relatively sunk.Cenozoic eraIt was the heyday of the development of the Bohai Basin, which continued to decline on the basis of the Mesozoic Era, and was controlled by NE-NNNE trending faultsRift basin。On the basis of overall decline, accompanied by differential movement, four secondary depressions are formed inside: Laizhou Bay depression is thin, only 4980 meters;The sedimentary thickness of Liaodongwan depression is about 5200 meters;The sedimentary thickness of Bohai Bay depression is about 6270 meters;The thickest deposit is Bozhong Depression, which is more than 7000 meters thick.Early Paleogene（Kongdian Group）The sedimentary layer is 500-600m thick, mainly dark gray, grayish green and purplish brown mud layer and sandstone.Mudstone contains biological fossils such as Hebei worms and tall backed spindle worms. Sandstone is light gray silty sand and fine sand. The mineral composition is mainly quartz, with good sorting. There is a thin layer of grayish brown oil shale at the bottom, which has been drilled under this layer in some areasMarl, dolomite, conglomerate at the bottom.
The sedimentary facies show that the Bohai Sea in the early Paleogene is a lowland and lake formed by uneven subsidence of the crust. The sediments are mainly continental, but some lakes are connected with the sea, so ostracod siltstones were deposited.Middle Paleogene（Shahejie Group）The sedimentary layer is 100-400m thick, which is light gray, gray green or dark gray mudstone layer.The environment of this sedimentary process is unstablebasaltOverflow and sedimentation are also different.In the late Paleogene (Dongying Formation), there are mudstone and sandstone layers with a thickness of 200-500 meters, and the whole stratum gradually thickens from top to bottom (that is, mudstone sandstone conglomerate), which reflects thatPaleogeneThe late Bohai Sea was in a lake environment, withFluviationThe sediment is mainly variegated sandstone and mudstone.
3. Upper structural layer
Bohai Sea Area Map
It is the continental lacustrine deposit andthe quaternary periodMarine sediments.Himalayan MovementThe imbalance between uplift and depression in the Early Tertiary was ended, and a unified large and stable subsidence depression was gradually formed in the Late Tertiary, and the sedimentary center moved to the Bozhong Depression in the central Bohai Sea.
The Upper Tertiary can be divided into Guantao Formation andMinghuazhen FormationIt is mainly composed of continental variegated clastic rock formation. In the late Minghuazhen Formation, seawater is occasionally flooded, so there are a few marine interbeds.The sediment thickness is more than 2000 meters.The Quaternary Bohai Sea entered a new development period, and the lake basin sank significantly and was submerged by seawater to form the present Bohai Sea.A large area of marine sand, silt and clay of the Pingyuan Formation were deposited.During the whole Quaternary period, the sea level rose and fell many times, and threeShell dikeThe oldest is 7-10 meters above the sea level, about 4270 ± 120 years ago, the middle is 4-5 meters higher, and the latest is 2-3 meters higher, 2000-2500 years ago.It shows that the sea level has decreased three times since the late Middle Holocene.
A large number of people are found in Laizhou BayAncient oysterReef, which proves that the sea level has declined significantly since 5500 years ago.During the drilling in Tianjin area, it was found that the sea level has risen twice since 22900 years ago and 10000-8000 years ago.It can be seen that the Bohai Sea was formed late and is characterized by ascending and descending movementsNeotectonic movementIt is strong.
The formation of the Bohai Sea has experienced vicissitudes from land to lake to sea in the geological history.The Bohai Sea is a nearly closed sea, and its hydrology and physics are greatly affected by the land. On the one hand, the Liaohe River, Luanhe River, Haihe River, Yellow River and other rivers continuously deposit sediment with water, changing the seabed andCoastal geomorphology。The accumulation of a large amount of sediment makes the depth of the Bohai Sea shallower, with an average depth of 18 meters. More than 50% of the water depth in the whole sea area is less than 20 meters. Only the southern tip of Liaodong Peninsula has a depression with a depth of more than 70 meters.On the other hand, the thermal dynamic of sea water is deeply affected by land, and the seasonal variation of surface water temperature is obvious.The water temperature can reach 24-25 ℃ in summer and about 0 ℃ in winter. Except for Qinhuangdao and Huludao, freezing is common, but the ice layer is not thick, generally 15-30 cm, and the ice age varies from 1-3 months.
The salinity of the Bohai Sea is low, and most of the sea areas are below 30 ‰.The wind and waves on the sea are small, and the average wave height along the coast is 0.3-0.6m.The Bohai Sea is rich in prawn, crab and yellow croaker.The coastal mudflats have good water storage conditions, which are conducive to salt production. The salt field producing Changlu salt is the largest sea salt field in China.Abundant oil and natural gas resources have been found and exploited in the Bohai Sea, and oil production is increasing year by year.There areTianjin Xingang、Qinhuangdao PortAnd other famous ports, which are connected with the Yellow Sea through the Bohai Strait, are the main routes to the sea for the provinces in North China, Northwest China and Northeast China.
Ecological characteristics
A corner of the Bohai Sea
There are 40 rivers and streams along the coast of the Bohai Sea, including 19 along the coast of Laizhou Bay, 16 along the coast of Bohai Bay, and 15 along the coast of Liaodong Bay, forming three major water systems and three major bay ecosystems along the coast of the Bohai Sea.Rivers entering the sea carry a large amount of sediment to accumulate in three bays every year, forming broad Liaohekou Delta Wetland, Huanghekou Delta Wetland and Haihekou Delta Wetland at the top of the bay, with an annual land reclamation of 20 square kilometers.There are many kinds of wetland organisms, including reeds, scallions, Suaeda salsa, piedmont grass and algae, and more than 150 kinds of birds.Liaohe RiverThe estuary delta wetland and the haihekou delta wetland are China'sreedThe main production area of, where reeds are overgrown, provides a large number of high-quality raw materials for China's paper industry every year.
Estuary shallow water area along the Bohai SeaNutrient saltsIt is rich in food organisms and is the spawning ground, nursery ground and feeding ground for economic fish, shrimp and crabs.The deep water area in the middle of the Bohai Sea is not only an economic fish in the Yellow Sea and Bohai SeashrimpThe gathering and distributing center for crab migration is also the wintering ground for local fish, shrimp and crabs in the Bohai Sea.Therefore, the Bohai Sea has three major ecosystems: estuarine delta wetland ecosystem, estuarine ecosystem and deep water ecosystem in the central Bohai Sea.Circum Bohai SeaThe three urban agglomeration ecosystems interact with the three ecosystems of the Bohai Sea, forming theComplex ecosystem。
Liaodong Peninsulasouth endLaotieshanThe line between the west corner and Penglaitou on the north bank of Shandong Peninsula is the boundary between the Bohai Sea and the Yellow Sea.
The Bohai Sea is a semi enclosed inland sea of China in the west of the northern connection between the Liaodong Peninsula and the Shandong Peninsula.The Bohai Sea includes three bays, namely Liaodong Bay, Bohai Bay and Laizhou Bay, and the central sea area, with a sea area of 77000 km2, accounting for 1.63% of China's sea area.The Bohai Sea is surrounded by Hebei, Shandong, Liaoning and Tianjin, with a total of 13Circum Bohai Seacity.
In the past decades, rich and high-quality fisheries, portspetroleum, landscape and sea salt resourcesBohai RimThe economy is characterized by rapid development.The development of marine resources and marine industry have become one of the important areas of economic development in the region.
However, with the development and utilization of marine resources, the resources and ecological environment of the Bohai Sea have been greatly damaged at the same time.The environmental quality of the Bohai Sea has seriously deteriorated, which is manifested in the obvious pollution of the coastal zone, the expansion of the pollution scope, and the weakening of the ecosystem,Ecological environment degradation，red tide，EutrophicationEtc.The environmental situation of the Bohai Sea has attracted the attention of the government and research institutions.A lot of research work has been carried out on its environmental quality, such as ecosystem, environmental parameters, red tide, eutrophication, etc.
Fisheries, ports, oil, tourism and sea salt are the five dominant resources of the Bohai Sea.
The Bohai Sea has fertile water quality, high nutrient content, and abundant bait organisms. The annual production of phytoplankton is 140 million tons, and the annual production of fish is 490000 tons.The Bohai Sea is the cradle of the Yellow Sea and Bohai Sea fisheries, and is a good place for many kinds of fish, shrimp, crabs and shellfish to breed, live and grow, so it is called the "cornucopia".PrawnHairy shrimp、Small yellow croaker、HairtailIs the most important economic category.
The Bohai Sea ports have the advantages of high distribution density, many large ports and energy export ports, good physical and geographical conditions, developed economy, vast hinterland, rich resources, etc., and are an important sea channel for foreign trade in northern China.More than 100 ports have been built or should be built.
The Bohai Sea is rich in oil and natural gas resources. The entire Bohai Sea area is a huge oil-bearing structureDagang, Liaohe Oilfield andOffshore oilfieldThe Bohai Sea has become the second one in ChinaDaqing。As of February 25, 2024, Bozhong 26-6 OilfieldThe cumulative proven reserves have exceeded 200 million cubic meters, making it the largest metamorphic rock oil field in the world.[8]
The natural scenery along the Bohai Sea is beautiful, and there are many places of interest and historic sites. It is fully equipped with temperate coastal tourism and vacation resources with the theme of sunshine, sea water, beach, green and animals.
Bohai Sea is the largest salt production base in China, and its sediment and climate conditions are very suitable for salt production.Among the four sea salt producing areas in China, the Bohai Sea hasChanglu、Liaodong Bay、Laizhou BayThree.The underground brine reserves along the coast of Laizhou Bay are rich, reaching 7.6 billion cubic meters, equivalent to more than 800 million tons of salt. It is a rare "liquid salt field" with large reserves, shallow burial and high concentration.
hydrographic features
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Water temperature change
Bohai Sea is located inNorth temperate zone, no hot summer, no cold winter, annual average temperature 10.7 ℃, precipitation 500-600mm,Seawater salinity30 ‰.
The Bohai Sea water temperature changes are affected by the northContinental climateImpact: 0 ℃ in February and 21 ℃ in August.When winter comesqinghuangdaoandHuludaoOutside, the coast is mostly frozen.At the beginning of March, a large amount of drift ice often occurs, with an average water temperature of 11 ℃.The salinity of Bohai Sea seawater is only 30PSU (Practical Salinity Unit), which is the lowest in China's offshore due to the large amount of fresh water injection from mainland rivers.
Water quality characteristics
From 1994 to 1998, exceptLaizhou BayOutside 1997, TN concentrations in the three bays were significantly higher than those in the central Bohai Sea.From 1994 to 1998, the TP concentration in Liaodong Bay and Bohai Bay was also higher than that in the central sea area.From 1994 to 1996, the concentration of TP in Laizhou Bay was slightly lower than that in the central sea area. After 1996, the concentration of TP increased and exceeded that in the central sea area.In general, the concentrations of TN and TP in the coastal zone are higher than those in the central sea area.In addition, the concentration of TN and TP in the central Bohai Sea is relatively stable and changes gently, while in Liaodong Bay, Bohai Bay and Laizhou Bay, the concentration changes sharply every year.The reason for this situation is that the coastal zone area is more vulnerable to the impact of land activities than the central Bohai Sea area.Land activities have different frequency and degree of influence in different sea areas and at different times.Obviously, the water quality in the central Bohai Sea is the result of the mixed diffusion of pollutants from the coastal zone.Therefore, land activities should be considered as the ultimate cause of water quality decline and eutrophication in the central Bohai Sea.
It can be found that the scope of pollution has expanded from the estuary area to the entire coastal zone of the Bohai Sea, and the scope has increased significantly.In addition, it is reported that the seawater compliance rate dropped from 78.77% in 1992 to 49.05% in 1996.In 2001, the polluted area of the Bohai Sea increased from 24.7% to 41.3% in 2002.This result means that the water quality in the Bohai Sea has declined significantly in the past few years.TN, TP and petroleum exceed the standard.TN exceeded the standard seriously, while petroleum exceeded the standard slightly.Therefore, it can be inferred that the main problems of water quality and eutrophication in the Bohai Sea are caused by nutrient nitrogen and phosphorus.
When the concentration of pollutants does not change much, the polluted area of Bohai Sea also expands year by year.By analyzing the satellite remote sensing photos of the Bohai Sea, it can be clearly seen that the polluted area of the whole sea area was 16347 km2, accounting for 21.2% of the sea area in 1992, and increased to 39232 km2, accounting for 51.0% of the sea area in 1996.As a result, the polluted area has increased 2.4 times in five years.In addition, it can be seen that marine hydrology andOcean dynamicsCharacteristics play an important role in the diffusion of pollutants.stayocean currentUnder the effect of weak material transport, most of the polluted sea areas are close to the coastal zone, especially in the estuary area.This proves that the environmental quality of the Bohai Sea is mainly affected by land activities.
sea ice
In winter, the Bohai Sea freezes due to frequent strong cold waves.From mid November, late November to early December, the coast began to freeze from north to south;The sea ice gradually disappears from the south to the north from the middle of February to the first and middle of March of the next year, and the ice age lasts for more than three months.In January and February, the width of coastal fixed ice is generally within 1 km from the shore, while in the shoal area, the width is about 5-15 km, and the common ice thickness is 10-40 cm.There are many piles of ice in estuaries and tidal flats, some of which are 2-3 meters high.Within 20-40 km away from the shore outside the fixed ice zone, there are many drift ice, which is roughly parallel to the coast, with a flow rate of about 50 cm/s.
According to historical records, the Bohai Sea has experienced three severe ice seals in the past 50 years: the first occurred in the winter of 1936;The second time was in February 1947;The most serious ice cover occurred in March to March 1969.
sea wave
withWind and wavesIt is mainly seasonal with the alternation of monsoon.North wave prevails from October to next April, and south wave prevails from June to September.The wind and waves in the Bohai Sea are most prevalent in winter, with wave height of 0.8-0.9m and period of less than 5 seconds.The average wave height in January is 1.1-1.7m, and it can reach 3.5-6.0m when the cold wave attacks.Between summer and autumn, there are occasional typhoon waves larger than 6.0 meters.The waves are the largest in the Bohai Strait and the central part,Liaodong BayandBohai BaySmaller.The average wave height of the Bohai Sea is mostly 0.1-0.7m, with the largest in the strait area, averaging 0.8-1.9m.
Tide and tidal current
Bohai Sea has independentRotating tidal wave systemThere are two semidiurnal tide waves (M) and one rotational system for diurnal tide waves (K).The semi diurnal constituent is absolutely dominant.The Bohai Strait is a regular semidiurnal tidal region because it is located around the "node" of diurnal constituent waves;There is a small irregular diurnal tide area outside Qinhuangdao and outside the mouth of the Yellow River near the two semidiurnal tidal wave "nodes".In addition, other areas are irregular semidiurnal tide areas.The tidal range is 1-3 meters.The average tidal range along the coast is the largest at the top of Liaodong Bay (2.7m), followed by the top of Bohai Bay (2.5m), and the smallest near Qinhuangdao (0.8m).The average tidal range in the strait area is about 2m.The tidal current is dominated by half day tidal current with a flow rate of 50-100 cm/s. The strongest tidal current is found near Laotie Shanshui Road, which reaches 150-200 cm/s, followed by Liaodong Bay, which is about 100 cm/s;The weakest tidal current area is Laizhou Bay, with a flow rate of about 50 cm/s.
cultural environment
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historical origin
In the Spring and Autumn Period, the people of Wu once sent boatmen from the Bohai Sea to Qi.
During the reign of Yuanfeng in the Han Dynasty,Yang ServantAnd cross the Bohai Sea to crusade against Korea.
In the 17th year of Emperor Kaihuang of the Sui Dynasty, he attacked Korea and madeZhou LuoxuanFrom Donglai Oceanwide to Pyongyang.In the seven years of the great cause, he attacked Korea and also madeCome and nurse the babyTake Pyongyang from Donglai.
In the 18th year of the reign of Tang Zhenguan, he made an expedition to KoreaZhang LiangTake Liaodong from Laizhou Oceanwide.Twenty one years, repatriatingNiu JindaWait to cross the sea from Laizhou to attack Korea.In the fifth year of Xianqing,Su DingfangCutting Baiji makes a mountain and a sea.Bohai Sea in the 20th CenturyGreat Martial ArtsSend the General Pirate Kou Dengzhou to kill the AssassinWei Jun。
In the second year of Jianlong of Song Dynasty, Jurchen traveled across the sea from Dengzhou to pay tribute.In the first year of Chonghe, Ma Zheng was sent to make Nuzhen a Taoist envoy, and attacked the Liao Dynasty with him, which led to the chaos of the Song Dynasty.
economic development
The cities around Bohai Sea are one of the more developed regions in China, where there are many famous large and medium-sized enterprises.In 1997, the GDP of 13 cities accounted for 7.8% of the national GDP.Therefore, the economy of cities around the Bohai Sea is very important for the whole country.According to the growth rate of industrial and agricultural GDP of the four provinces and municipalities around the Bohai Sea, the economy of these regions has maintained a momentum of rapid development.The industries include steel, machinery, electronic instruments, petroleum, petrochemical, shipbuilding and other industries, which play an important role in the national industry.Since 2007, the industry in this area has developed rapidly.From 1994 to 1998, the industrial GDP of Hebei and Shandong provinces continued to grow;Tianjin City and Liaoning Province maintained growth from 1994 to 1997, but fell back slightly in 1998.Although the growth rate of agricultural GDP is not as obvious as that of industrial GDP, especially after 1996, the agricultural development is stable, and the output value maintains a steady increase trend.During the remarkable economic development and urbanization process in the past decades, the cities around Bohai Sea have provided basic support for the development of the national economy.
Bohai area on satellite
The Bohai Sea is rich in fishery, port, oil, tourism, sea salt and other resources and its pleasantNatural environmental conditionsAnd injected infinite vitality into the economic development of the Bohai region.At the same time, due to the vigorous development of the primary industry, it has also driven the development of the secondary and tertiary industries such as marine chemical industry, ship building and repair, aquatic processing, petrochemical industry, textile, etc.In addition, the Bohai Sea beach is very wide, with a beach area of 5100 square kilometers and an annual siltation area of 20 square kilometersTidal flat resourcesIt provides a broad space for survival and development to solve the contradiction of more people and less land in coastal areas.In 2000, the population of coastal cities in the Bohai Sea was 35.8648 million, accounting for 23.8% of the population of coastal cities in China;Coastal cities in the Bohai Seagross domestic product545.326 billion yuan, accounting for 28.5% of the GDP of coastal cities in China.The Bohai Rim has become one of the regions with the highest population quality and density, the most developed economy, culture and education, and the strongest scientific and technological strength and industrial foundation in China.As early as nine thousand years ago, the Bohai Sea was still a shallow depression with low and flat terrain. Later, the sea level rose,Seawater intrusionTo form today's Bohai Sea.The Bohai Sea covers an area of 78000 square kilometers, with a coastline of 3784 kilometers and an average depth of 18 meters.The Bohai Sea consists of Laizhou Bay, Bohai Bay,Liaodong BayAnd the central basin.It is surrounded by land on three sides and connected to the Yellow Sea by the Bohai Strait on the east. It is a bottleneck semi closed inland sea, and its water exchange is extremely slow.According to experts' estimation, the cycle of the whole Bohai Sea water takes about 40-200 years, and its capacity of receiving and purifying pollutants is very limited.
environmental pollution
Due to the effect of population control measures, the population growth rate in 1994-1998 was at a relatively low level, but the actual population has been increasing.The tourism industry in this area developed rapidly from 1994 to 1998, with both the number of tourists and the tourism income increasing significantly.
In order to control the waste discharge caused by population increase, the national Bohai Sea Bihai Action Plan requires strengthening the urbanSewage treatment plantConstruction.
There are nearly one hundred ports along the coast of the Bohai Sea, with serious oil pollution.Yellow River、Xiaoqing River、Haihe River、Daliao River、Luanhe RiverAnd more than 40 rivers flow into the Bohai Sea all year round.In addition, industrial wastewater and domestic sewage from coastal cities and towns in Tianjin, Hebei, Shandong and Liaoning are directly discharged into the sea.
Hundreds of rivers flow into the sea, and a large amount of land-based sewage and pollutants flow into the Bohai Sea.According to statistics, the annual sewage volume entering the Bohai Sea amounts to 2.8 billion tons, accounting for 32% of the national sewage volume.Among them, Tianjin has 10-11 billion tons of sewage into the sea, and Beijing has 300 million tons.More than 700000 tons of all kinds of pollutants, accounting for 47.7% of the total amount of pollutants entering the sea, make the Bohai Sea a man-made sewage pool and a natural garbage dump.Liaodong Bay, Bohai Bay and Laizhou Bay are the most seriously polluted, and the pollution of the three bays accounts for 92% of the total pollution of the Bohai Sea.Pollutants mainly include inorganic nitrogen, inorganic phosphorus, petroleum andOxygen consuming organicsIn addition, there are heavy metals.
Liaoning ProvinceHuludao CityThe Wuli River, 35.5km long, is more specifically a sewage drain.Because along the riverJinzhouThe General Chemical Plant and Jinxi Petroleum Refining and Chemical Plant discharge nearly 30 million tons of sewage into the river every year,Huludao Zinc Plant1396 tons of zinc is discharged into the sea every year, accounting for 64.8% of the national total.The mercury content in the bottom sediment of the urban section of Wulihe River is about 90 tons, and the mercury content in the soil and crops within 100 meters along the coast is greatly beyond the standard.
Xiaoqing River is the main river crossing Shandong Province, with tens of thousands of tons of sewage flowing into the sea every year. It is said that in March 1998 after treatment, the river water was still brown, and the transparency of the water in Yangjiaogou section was less than 30 cm.
Liaodong BayOver standard rate of oil in sea area reaches 75%, of whichJinzhou BayThe oil pollution in the sea area reaches 100 ‰, and the industrial toxic and harmful waste residue is also advancing to Jinzhou Bay at the speed of 10 meters every year. Since 1992, it has created a waste beach of two square kilometers, forming a "wonder" of sea retreat and waste advance.In addition, 467 hectares (more than 7000 mu) of beaches with rich shellfish resources have become dead beaches in barren areas, and there are 7 km2 of waters in Jinzhou Bay that are lifeless.
A large amount of nitrogen and phosphorus enter the sea, making the sea water appear strong eutrophication, resulting inred tideIt happens frequently.Red tides in the Bohai Sea have occurred more than 10 times every year since 2007. From August to October 1989, Tangshan City, Hebei ProvinceTanghai CountyA large area of red tide occurred and affected Liaoning, Shandong and Tianjin, with an area of 1300 km2 and a loss of more than 300 million yuan.1990Laotieshan WaterwayThe red tide with an area of 1000 km2 occurred, which also caused huge economic losses.
Pollution in the Bohai Sea has seriously endangered the normal life and health of local people through the food chain.It has caused the detection values of mercury, lead and arsenic in the hair of fishermen in the region to exceed normal, and the incidence of cancer has increased significantly.In addition to Hebei Province, the mortality rate of malignant tumors of fishermen in other provinces and cities is higher than that of farmers.In Yudongbu Village, Shandong Province, hundreds of people died of cancer in the 1980s, and more than 60% of children were found to have hepatomegaly.The arsenic and mercury contents in the hair of Huludao fishermen are far higher than normal.The groundwater in Wulihe section is polluted, and all the civil pumped wells are abandoned. People have to spend more than 50 million yuan to find new water sources.
qinghuangdaoSea area pollution, aquaculture in 10 nautical milesScallop in ShellThey cannot grow, and the water surface is discolored and turbid.The relevant reports only focus on 2007. The Qinhuangdao sea area is still a relatively polluted area, but in 2009, no one paid attention to the situation. We can't find data to let us know the situation, but the data is only rational, can you imagine?It is more intuitive to see the sea water at this time with our own eyes. The above description is the true expression of local residents at the seaside. I don't know how we feel.
Governance development
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Marine development activities
The marine development activities around the Bohai Sea can be divided intoMarine industryChange of output value, such as fishery, oil, natural gas, sea salt, etc.It can be seen that from 1994 to 1998, all marine industries showed an overall growth trend.
Circumjacent situation of Bohai Sea
West water diversion
overview
“south-to-north water diversion”Water from the south will be introduced into the north to alleviate the problem of water use in the north.Now, someone has proposed“West water diversion”The water of the Bohai Sea should be introduced into the desert to turn the Gobi into fertile land.
On November 5, 2010, experts from all over the country made suggestions to promote this project at the "Summit Forum on Land Sea Coordination and Seawater Diversion to the West" held in Urumqi.But for many people, the idea of introducing sea water into the desert is absurd.So, is the "Western Water Diversion" a dream or a trick?
Who made a concluding speech for the summitChina High tech Industrialization Research AssociationZhang Baoyin, secretary-general of the Marine Branch and senior engineer, said that the "water diversion to the west" was no nonsense.
Zhang Baoyin explained, "The sea water is inexhaustiblehunshandake sand land Only more than 400 kilometers, very close geographical location. "It is reported that the Hunshandake Sandy Land is one of the deserts that pose the most serious threat to the climate of Beijing.The Bohai Bay is infused by the Yellow River, Haihe River, Luanhe River, Liaohe River and other continental rivers, with relatively low salt content. The unique geographical conditions make the Bohai Bay the best choice.
According to scholars,Northwest ChinaThe amount of rainfall depends on three necessary and sufficient conditions: first, the westerlies;The second is the alpine condensation system;The third is the source of water and steam supply.Among them, westerlies and alpine condensation systems are available, but water vapor supply sources are unavailable due to water shortage and drought.If the water from the Bohai Sea, which is 500 kilometers deep in the northern mainland of China, is transferred to the east to fill the deserts from Inner Mongolia to XinjiangTectonic basinAnd large and small salt lakes to form artificial sea, suppress desert, expand wetland area, provide wet climate conditions in northwest China through natural evaporation of sea water, and increase water vapor supply source of rainfall.In this way, the arid and harsh ecological environment in northwest and north China will be fundamentally changed.
In the idea of "seawater diversion to the west", the most questioned by the outside world is whether the introduction of seawater will affect the inland soil structure and cause irreversible ecological impact.Zhang Baoyin said that this would never cause any consequences.He said that the sea water in the Bohai Bay is connected to the Pacific Ocean, and the general self purification cycle is five years. The introduction of sea water in the Bohai Bay can artificially shorten the purification cycle, promote environmental change in the Bohai Bay area, and even promote the development of aquaculture.
Experts have preliminarily determined the selection of transportation materialsFRP pipeIt is not easy to be corroded by seawater and has strong stability. It can be used for 20-30 years generally."It is preliminarily planned that the diameter of the steel pipe is 8 meters, which can basically meet the demand. The first step to enter the inland sea water is to passSemipermeable membrane filtrationTo achieve the purpose of separating fresh water from salt, so as to ensure that the water source entering the inland will become fresh water in the later period, and avoid the harm of land salinization and alkalization caused by sea water flowing through the inland. "
When the reporter asked whether this was a loss making business, Zhang Baoyin did not agree.He calculated an account for the reporter. The average cost of water per ton was 4 yuan, and the price of water for local coal chemical production and gas was 12 yuan per ton, which also earned a difference of 8 yuan."Water that cannot be used by industry can be used for agriculture, such as fish farming and ranching, so that local industry and agriculture can develop."
Basic concept
The sea water is lifted from the northwest coast of the Bohai Sea to an altitude of 1200 meters to the southeast of Inner Mongolia Autonomous Region, and then flows through YanshanYin MountainTo the north, out of Langshan Mountain and into the westJuyan SeaAnd enter Xinjiang by bypassing Mazong Mountain.It is divided into north, middle and south branches in Xinjiang, and the north branch entersEbinur Lake, middle branch enteringTurpan、HamiBasin, south branch entersLop NurBasin.
The sea water transferred from the west forms an "artificial sea" and a large wetland in desert areas. By natural evaporation, it increases the humidity in the air, increases the local rainfall, improves the local ecological environment, realizes the large cycle of water, and reaches the goal of harnessing Chinadesert、sand storm, completely changing North ChinaNorthwest ChinaThe purpose of poor ecological environment.
Five major problems
1. Salinization. The water diversion canal along the border of Inner Mongolia has dried up the salinization depression, so salinization has little impact;
2. Energy problem, China's power supply has exceeded demand;
3. The one-time investment of the project water lifting station is not large, and it will be implemented in 30-50 years, when China's economy is developed, it will be a strategic infrastructure project in the northwest.The operation investment of the project is huge, but the output is larger.For example, the annual increase of 100 billion cubic meters of seawater desalination water is 100 billion US dollars at international prices, which is 1/10 of China's GDP in 2000;
4. Evaluation of water and steam loss.It is estimated that most of the evaporation water vapor from the water diversion falls to the west of the 300 mm precipitation line of Baotou Lanzhou line, even though Shaanxi, Gansu, Ningxia, Hebei and Shanxi regions can be considered in the east, theoretical analysis shows that the water vapor loss rate of the water diversion from the west is roughly equal to the natural shrinking rate of the northwest wetland;
5. Winter operation.The sea water flows westward along the line of 42 degrees north latitude. In winter, water flows under the ice as usual, and ice can be used to make fresh water. Only in Inner Mongolia, 3000 kilometers long from east to west, water can be supplied for planting trees and grass, forming China's first windbreak sand forest belt of 50-60 kilometers wide and 3000 kilometers long.
question
As soon as the news of "Seawater Diversion to the West" was reported by the media, it immediately caused a heated discussion on the Internet. Some netizens joked that this idea was the same as that of the previous yearMou QizhongThe proposal of "blow a hole in the Himalayas, let the warm and humid air flow of the Indian Ocean come in, and Tibet will become the real Jiangnan" has a competition.
Netizen: "If the idea of diverting Bohai Sea water into Xinjiang is correct, why do Beijing and Tianjin not make full use of the sea water and still have to goYangtze RiverWater diversion from the Yellow River? "
Netizen: "Many coastal cities haveSeawater backflowAnd lead to the change of soil acidity and alkalinity.If the Bohai Sea water is introduced into Xinjiang, once the sea water leaks along the way, Xinjiang, which lacks rainfall, is likely to lead to land salinization. "
Netizen: "Although China has been able to desalinate seawater technically, the cost is still not cheap. Moreover, the project may lead to land expropriation along the line, which may lead to forced demolition. Does the project fund breed corruption?"
Netizen: "Do you pass through an earthquake zone? Can glass fiber reinforced plastic resist earthquakes?"
Netizen: "In the case of repeated prohibitions of fraud in all walks of life, will the glass fiber reinforced plastic pipe leak? Will the surging river become unbearable for glass?"
Netizen: "Where the sea water flows, there are many long winters. What should we do if it freezes and stops flowing? Even if the sea water is successfully transferred to the west, how can we ensure that the evaporated water only rains locally, without forming a new air circulation mode?"
Comprehensive management of the Bohai Sea
The Ministry of Ecological Environment, the National Development and Reform Commission and the Ministry of Natural Resources jointly announced on December 11, 2018《Action Plan for Comprehensive Management of Bohai Sea》, proposed the timetable and road map of the battle.The action plan proposes that, through three years of comprehensive management, by 2020, the proportion of good water quality (Class I and Class II water quality) in the coastal waters of the Bohai Sea will reach about 73%, the natural shoreline retention rate will remain at about 35%, the coastal wetland renovation and restoration scale will not be less than 6900 hectares, and the renovation and restoration shoreline will increase by about 70 kilometers.The action plan identified four key actions: land-based pollution control action, marine pollution control action, ecological protection and restoration action and environmental risk prevention action.[6]
Since 2018, 1.29 billion yuan has been raised and allocated to support the cities along the Bohai Sea in Liaoning to carry out comprehensive governance projects in the Bohai Sea.Next, Liaoning will continue to supervise and dispatch key areas, tasks and projects, guide cities to speed up the implementation of funds, manage and use funds well, give full play to the role of financial functions, and support the comprehensive governance of the Bohai Sea.[7]
