(Hainan Geological Survey Institute, Haikou 570206)

Hainan Island is rich in tidal flat resources, and it has a unique advantage to develop mariculture. According to the development status, economic benefits, aquaculture methods and development trend of coastal mariculture in Hainan Island, the environmental geological problems caused by mariculture and its harm to mangroves and green husk forests were analyzed. This paper studies the causes of the destruction of coastal forest, coastal environmental pollution (seawater pollution, groundwater pollution and salinization), soil erosion, barren land (desertification), harbor siltation, land salinization, coastal erosion and the destruction of mineral and tourism resources, and puts forward some suggestions and corresponding countermeasures for the coordinated development of mariculture and environmental protection.

Keywords: coastal zone; Mariculture; Geological environment; environmental protection

1 coastal topography

Hainan Island is located between east longitude10837' ~1003' and north latitude1810' ~ 2010', and the coastal zone is10' from the coastline.

1. 1 coastal types and distribution

The coastline of Hainan Island is tortuous, with 68 harbors and a total coastline of 1528km. There are four types of coasts: mud coast, sand coast, rock coast and biological coast. According to its characteristics, it can be divided into three sections: the northern section, from Baimajing in the west of Danzhou City to Qinglan Port in the east of Wenchang City, is mainly a marine erosion accumulation rock bank of volcanic (basalt) platform, and some sections such as Nandujiangkou, Haikou Bay and Dongzhai Port are sandy and muddy coasts; From Dongzhai Port in Wenchang City to Yulin Port in Sanya City, the eastern part is mainly a small harbor-type accumulation landform sand dike and mud dike evolved from drowning valley. In addition, there are rock banks in some areas such as Baohujiao, Tonggu Tomb, Nanwan Monkey Island and Jiefen Tomb. The western section from Yulin Port in Sanya City to Baimajing in Danzhou City is mostly a marine terrace sand bank surrounded by sand dikes, and some sections such as Meishan in Sanya and the north of Changhua Port in the Yangtze River are rock banks.

1.2 coastal landform

Wenchang city in the northeast is mainly a marine plain with low terrain, with an altitude of 5 ~ 20m. The northern Haikou-Yangpu area is dominated by basalt platforms, and the terrain is slightly undulating; Yangpu, west of Haitou, is a marine plain; Haitou south to Ledong 9 is a coastal plain; From Jiusuo to Sanya in the east, it is a magmatic hilly area; Sanya is a coastal plain-hilly area from north to east to Lingshui; From Lingshui to Wanning, it is a magmatic hilly area. Generally speaking, the northern coastal zone is dominated by plains and platforms, with low terrain; The east, south and west are mainly plains and hills, and the terrain fluctuates greatly. The highest altitude is Lingshui Mengshuiling 841m.

Numerous bays, coastal plains, beaches, clear seawater and high water temperature have created unique natural environmental conditions for the development of mariculture, especially in the western coastal waters of the island, which is an ideal place for the development of mariculture, and has the characteristics of many suitable species and rapid growth of aquaculture species. At present, only 8483km2 of shallow sea area suitable for aquaculture has been utilized, and the development potential of mariculture is huge.

2. Overview of mariculture development

In 2000, the mariculture area of the whole province was 14526 hectares, and the output value was1889 million yuan. According to different culture methods, it can be divided into cage culture and pond culture. Fish and shellfish are mainly cultivated in cages, and prawns are mainly cultivated in ponds. In 2000, the shrimp culture area in the province was 7,759 hectares, accounting for 53.4% of the marine culture area, with an average output of 2,997 kg and a total output value of1/kloc-0.25 billion yuan, accounting for 60% of the marine culture output value. Shrimp culture in seawater, the shrimp culture area in high-level pond is 1486 hectares, accounting for 19.2% of the shrimp culture area in seawater, with an average yield of 6345 kg/hectare. The average output of prawns in low ponds is 2204 kg/ha, which is only 35% of that in high ponds. Shrimp culture has become the main industry of marine culture in our province, and high-pond shrimp culture has become the leading industry of shrimp culture.

Figure 1 Coastal Zone Distribution Map of Hainan Island

Table11996 ~ 2001development of shrimp production in Wanning City

Marine shrimp culture in Hainan Province is mainly distributed in Wenchang, Qionghai, Wanning and Lingshui in the east and Sanya and Ledong in the south. There are many lagoons in these cities and counties, which are conducive to the development of low-level ponds to raise shrimp; At the same time, these cities and counties also have long sandy coasts, which are easy to dig and are conducive to the development of shrimp culture in gaotang.

According to the analysis of the development trend of shrimp culture in Wanning from 1996 to 200 1 year, the total area of shrimp culture was basically stable at about 1000 hectares in the past six years, and the area of high ponds was constantly expanding, while the area of low ponds was relatively stable, but the yield and unit yield increased greatly (table 1).

According to 1998 and 1999, the aquaculture area and output of some coastal cities and counties in Hainan Province have been greatly improved compared with 1998, and the marine aquaculture industry has developed rapidly (Table 2).

Table 2 1998 and 1999 List of Gaotang Culture Area and Yield in Coastal Cities and Counties of Hainan Province.

3 environmental geological problems caused by mariculture

The contribution rate of the development of marine aquaculture in our province to the GDP of the whole province has increased year by year, which has effectively promoted the adjustment of the industrial structure and the rapid development of social economy in the whole province. However, due to the lag of planning control and management, extensive aquaculture has led to the destruction of coastal ecological environment to varying degrees.

3. 1 Destruction of coastal defense forest

According to the survey, by the end of 1998, the area of deforestation in coastal cities and counties of the whole province due to the development of mariculture (mainly gaotang) was as high as 5,795 mu, of which 2,246.6 mu and 3167.51000 m away from the coast. 10 coastal cities and counties1at the end of 1998, the total deforestation area caused by the development of mariculture was 48 18 mu (see table 3).

Table 3 Deforestation and pond digging in Hainan Province (as of the end of 1998)

According to the comparative analysis between the 1995 image and the 2000 image, the coastal high tide of Wenchang Gaolongwan extends inland by about 500m, and the vegetation along the 1995 coastal forest is well preserved, but the coastal zone was replaced by dense water bodies in 2000 (see box in Figure 2). According to the field investigation, the dense water body in the coastal zone is a high-level shrimp pond that has developed rapidly in recent years. In addition, during the period from1995 to 2000, other coastal cities and counties also developed high-level pond culture to varying degrees. Although high-level pond culture has promoted the rapid development of local economy, it has also damaged coastal vegetation or grassland to varying degrees, causing certain harm to the coastal ecological environment of our province, and even mangroves and green husk forests have been damaged to some extent.

Mangrove is a tropical forest growing on the beach, and it is a unique type of aquatic tree community along the tropical coast. Mangroves are banded in estuaries or lagoons, just like a great green wall, which can resist the impact of strong winds and waves, protect coastal banks and protect the environment. It is known as "undersea forest" and "Coast Guard".

According to the statistics of 1956, at that time, there were 10000 hectares of beach mangroves in the whole island, which were distributed in Xinying Port, Xinying Port, Magnaud Port and Huachang Port in the northwest and north, Dongzhai Port, Puqian Port and Qinglan Port in the northeast, Boao Port and Gangbei Port in the east coast, Xincun Port, Sanya Port and Wanglou Port in the southeast and south. Due to the influence of land reclamation, the mangrove area decreased, leaving only 3200ha in the whole island from 65438 to 0986. In 1990s, influenced by mariculture, farms were built in coastal areas due to deforestation. By 200 1, only 2753ha is left (Table 4). In recent 10 years, mangroves have been severely damaged and shrunk by 47%, especially in Xinyinggang. From 199 1 to 200 1 year, due to the large-scale excavation of aquaculture ponds, the protection efficiency gradually declined and the ecological environment deteriorated, and the mangrove forest decreased from 8. 18km2 to 1.99.

Fig. 2 Comparison of remote sensing images of Gaolongwan coast in Wenchang.

Table 4 Present situation and evolution of mangroves

Fig. 3 Degradation of mangroves in Xinyinggang.

Green bark forest is a low shrub unique to tropical coastal sand banks and sandy land, which grows on coastal sand banks and sandy land to protect coastal sand banks from erosion and erosion by waves and protect coastal ecological environment. During the Guangxu period of Qing Dynasty, a nature reserve was established in Li Ji (Shimeiwan), and it was established as a "provincial" nature reserve by Hainan Forestry Bureau in June 1980+00, which made the green husk forest in the reserve relatively well protected and was the only pure forest in the world. However, in recent years, due to the large-scale excavation of high-level aquaculture ponds, the green husk forest in this area has been seriously damaged. From 1996 to 2002, the green husk forest in the nature reserve decreased from 1066.7 hectares to 948.9 hectares, a decrease of 1 17.8 hectares (1%).

1999, the General Office of the Provincial Party Committee and the General Office of the Provincial Government jointly issued the Notice on Further Improving the Special Management of Mangroves in Coastal Defence Forests, although by the first half of 2006, the area of returning farmland to forests in the whole province was 172 hectares, accounting for 55% of the pond area that should be filled. However, the new phenomenon of deforestation by digging ponds still occurs from time to time, and the deforestation area is often about 20% ~ 30% larger than that of the built high-level ponds. After deforestation, coastal sandstorms will wreak havoc, especially in typhoon season, storms will drive straight in and coastal villages will be more seriously affected.

3.2 Environmental pollution

3.2. 1 seawater and beach pollution

There are many pollution sources in high-level pond culture: (1) chemical fertilizer and manure; (2) Lime, formalin and copper sulfate used for cleaning shrimp ponds; (3) Disinfect the chlorine dioxide released from the prawn pond. (4) The feed contains a lot of antibiotics; (5) excreta. These pollutants lead to the pollution of seawater and beaches, especially in the late stage of shrimp culture and pond cleaning. The concentration of pollutants is very high, and its wastewater is basically discharged directly into the sea without treatment, which has caused serious pollution to the coastal waters. In August, 2002, Hainan Provincial Environmental Monitoring Center Station monitored the Tanwenhou High Level Pond Breeding Base in Puqian Town, Wenchang City. The results showed that the CODcr of the wastewater was 224 ~ 252 mg/L, which exceeded the standard 1.24 ~ 1.52 times. The COD index of water quality is between Class I and Class II, and the monitoring value is between 1.00 ~ 2. 18 mg/L, but it is being affected by a large amount of wastewater (manganese method, the total COD at the discharge port is 2 1mg/L), which is 0/0 times higher than the Class II standard/kloc-0. Inorganic nitrogen in wastewater reached 7. 1 1 ~ 7.26 mg/L, which was nearly 35 times higher than the second grade standard of seawater. The active phosphate is 0. 122 ~ 0.459 mg/L, which is 3 ~ 14 times higher than the second class standard of seawater. The suspended solids in wastewater reached 88 ~ 1 16 mg/L, which exceeded the discharge standard18 ~ 46 mg/L; Moreover, the fecal coliform group in this sea area is 940 ~ 1200mg/L, which is 5.7 ~ 7.6 times higher than the water quality standard of shellfish for human consumption.

According to the analysis results of zooplankton diversity index in the coastal waters of Hainan Province, the zooplankton diversity index in Shimei Bay is higher than that in other places, indicating that the diversity index of Shimei Bay belongs to moderately polluted water bodies, and the diversity index of Xinyuan intersection in Qinglan and Ding Jiao in Meishan is close to heavily polluted water bodies, and the coastal water bodies at Xinyuan intersection in Qinglan are more serious than those in other two places (Table 5).

Table 5 Diversity Index of Zooplankton in Hainan Offshore

In terms of benthos, polychaetes are the main species of benthos in Hainan Province. Erythrina is distributed in all sampling points except the intersection of Xinlan, which is 500 meters away from the shore. Therefore, Magnolia grandiflora is a common species in all sampling points, and it is also a species resistant to organic pollution, especially at the intersection of Xinlan in Qinglan and Meishan Peak, which shows that it is a dominant species.

After counting the zoobenthos at each sampling point and weighing them with an analytical scale, the results show that the number of zoobenthos in Shimei Bay is the largest, while the number of zoobenthos at the intersection of Xinyuan and Meishan Corner in Qinglan is relatively small, and there are more zoobenthos in Shi Mei. However, the number of species in the other two points has also decreased, indicating that the lack of aquaculture in Shimei Bay and the sea area has little impact on benthos. However, the sewage and waste discharged from a large number of shrimp ponds and fish ponds at the intersection of Lan Xin and Meishan Corner in Qinglan have caused some pollution to the coastal waters, and the survival of some benthos is threatened, which not only reduces the species, but also reduces the quantity and biomass (Table 6).

Table 6 Number and biomass of benthic organisms

According to the calculation results of Shannon-Weaver diversity index equation, it is considered that the diversity index below 1 is a heavily polluted area, 1 ~ 3 is a moderately polluted area, and above 3 is a clean area. According to the calculation, the diversity index of the coastal waters at the intersection of Xinyuan in Qinglan and the top of Meishan Jiaotou is below 1, which is a heavily polluted area. However, the diversity index of Shimei Bay is between 1.7 ~ 1.9, which is a moderately polluted area. This shows that although there is no aquaculture near Shimei Bay, there is also shrimp pond wastewater discharge 4 ~ 5 kilometers away from Shimei Bay, which indirectly affects Shimei Bay (Table 7).

Table 7 Index Table of Benthic Biodiversity

The above investigation results show that large-scale mariculture is carried out in the coastal waters of our province, and a large amount of untreated wastewater is directly discharged into the sea, which has a certain impact on the ecosystem of the coastal waters. The number of marine life increases, species decreases and biodiversity decreases. In particular, aquaculture wastewater contains a lot of organic nutrients such as nitrogen and phosphorus, which will promote the reproduction of coastal algae. The number of algae at the intersection of Xinyuan Road and Meishan Corner in Qinglan has reached or exceeded the eutrophication threshold. If we don't pay attention to it and meet the right conditions, it is inevitable that seawater red tide will break out.

The wastewater from shrimp culture in high-level ponds in our province is discharged along the ditch bank, which not only causes serious pollution to the beach landscape, but also fails to make full use of the environmental capacity of the ocean, so that pollutants are concentrated in the coastal zone of about 200m, causing great pollution. Moreover, the water intake point is generally about 100m away from the sewage outlet, and the aquaculture wastewater is easy to spread to the distance of 100 ~ 200 m due to the ebb and flow of seawater, causing its own pollution, which poses a severe challenge to the environmental advantages that our province relies on to develop shrimp farming, and the current shrimp farming methods lack sustainability.

3.2.2 Groundwater pollution and groundwater salinization.

According to the survey results, most of the high-level ponds built a few years ago have no anti-leakage facilities on the wall and bottom of shrimp ponds, and there are too many openings in the main water inlet and drainage channels. During the period of water inflow or drainage, many large-scale seepage often occurs, which leads to salinization of some farmland and pollution of drinking water sources. For example, nine barrels of shrimp ponds in Tanmen Village 100 mu in Tanmen Town, qionghai city polluted the water quality of nine barrels of farmland and wells in nearby Mengziyuan Village. Farmland has been salinized, which makes wells unsuitable for farming and drinking. In June, 5438+0998+00, some villagers petitioned the qionghai city Municipal Government for many times.

In recent years, anti-seepage measures have been basically adopted in newly built high-level ponds. There are cement walls around the ponds and plastic films at the bottom, but the water in the high-level ponds still leaks to the outside. The investigation shows that the chloride concentration of groundwater near most high-level ponds meets the drinking water quality standard (less than 250mg/L), but some high-level ponds have high salt content and chloride concentration. For example, in urban and rural areas of Lingshui County, the chloride is1.71×103mg/L; Wang Lin Zhenjiang Sea Farm in Sanya City, with salinity of 2.0 ‰; He Kang Farm, Wanglin Town, Sanya City, with salinity of 4.1‰; Longmuwan Farm in Jianfeng Town, Ledong County, salinity1.9 ‰; Sun City Farm, Foluo Town, Ledong County, salinity 1.5‰. 1999 65438+ 10, villagers in Bozhong Village and Futi Village, Xia Mei Township, Lingao County reported that most of the wells in the village were salty and could not be drunk. Investigation and monitoring show that the salt content of groundwater at 200m from Bozhong Village to the east of Dongying Gaochi Marine Farm is 18.0%, which is 44 times that of the control point (more than 500m away from the farm), and the chloride content of groundwater at 200m is1.10/04mg/L. The salt content of groundwater at the distance of 200m from Futi Village to the west of Gaochi Farm in Oak Source is 25.6%, which is 56 times that of the control point, and the chloride content of groundwater at the distance of 200m is 1.40× 104mg/L, which is 36 times that of the control point and 55 times higher than the national groundwater quality standard III.

3.3 Destruction of tourism resources

There are dozens of shrimp fry farms in Fengjiawan, Wenchang, and the aquaculture sewage is directly discharged into the sea without treatment, which pollutes beaches and seawater and directly affects the growth of eucheuma and coral reefs. According to the recent survey, almost all corals in this coastal area have died, so there is no value in developing diving tourism. Ledong Lingtou Bay within the jurisdiction of Jianfengling National Park is connected with the mountains and seas of Jianfengling, which is the most ideal area for coastal tourism and forest tourism in our province. However, because many windbreaks along Lingtou Bay were replaced by advanced ponds, Jianfengling National Forest Park lost the opportunity to combine blue tourism with green tourism.

3.4 Soil erosion, land desertification and port siltation

3.4. 1 soil erosion

Under natural conditions, the coastal zone is flat, the water flow is slow, the erosion to the surface soil is small, and the degree of soil erosion is low. Except for serious local soil erosion caused by river bank erosion and collapse in river delta area, the development degree of soil erosion in most other areas is low.

In recent years, with the rapid development of marine aquaculture, a large number of high-level aquaculture ponds have been built on the sandy land of coastal sand dikes, and coastal defense forests and shrubs have been cut down. Vegetation is seriously damaged, which reduces the ability of soil and water conservation. Surface water directly washes loose soil layer, causing soil erosion under the action of water flow. The construction method of in-situ excavation and in-situ filling is adopted for the high-level breeding farm built on the sand embankment, and the excavated soil in the pond is piled around to form the pond embankment. The dam body is untreated, and the topsoil is loose and steep, which is easy to form soil erosion under the action of rain.

According to the analysis of relevant data, in recent years, the coastal sections where high-level aquaculture sites are concentrated have suffered from different degrees of soil erosion, cultivated land and farmland have been flooded, and rivers and bays have been silted up. Harmful to the surrounding environment. Sediment deposition is formed in the coastal waters of Wenchang Gaolongwan, qionghai city Changpo, Wanning Shenzhou Peninsula, Lingshui Xincun Port and Sanya Meishan, which has a great impact on the ecological environment in shallow waters.

3.4.2 Land Desertification (Desertification)

The content of soil particles, organic matter and humus in coastal sandy land is low, and the soil layer has strong water permeability, poor water storage and poor plant growth conditions. Under natural conditions, Casuarina equisetifolia, wild pineapple, shrubs, etc. It mainly grows on the sandy land along the sand embankment, with few herbs. Because building a breeding ground on the sandy shore requires cutting down trees and destroying plants.

Larger, resulting in bare sand dunes on the surface. Under the action of sea breeze, sand dunes move inland, burying farmland and crops, and clay, organic matter and humus on the soil surface are blown away by sea breeze, leaving sand grains such as medium coarse sand, fine sand and semi-coarse sand on the surface, which leads to the decline of soil fertility, the difficulty of plant or crop growth and the formation of land degradation (or desertification). According to the analysis of the geological survey data of coastal mariculture eco-environment, in recent years, there have been different degrees of land desertification in coastal mariculture areas, and its area is about 20% ~ 25% of the high-level land area. The eastern coast of Hainan Island has a humid climate, with rainfall greater than evaporation, good conditions for plant growth and easy reclamation of barren land. However, the west coast is dry, the evaporation is greater than the rainfall, and the plant growth conditions are poor, so it is difficult to reclaim wasteland.

3.4.3 Port siltation

Siltation in the harbor is caused by serious soil erosion around the bay and upstream of the river, high sediment concentration in the river and poor seawater circulation in the bay. In recent years, the harbor siltation caused by the excavation of high-level aquaculture ponds and cage culture in the coastal sandy beach is mainly distributed in Xiaohai in Dong 'ao, the fork of Shenzhou Peninsula and Xincun Harbor.

In recent years, due to the large-scale excavation of the high-level aquaculture pond on the sand dike, a large amount of quicksand is discharged into the nearby sea fork (or small sea), which makes the sea fork and small sea in Dong 'ao form serious siltation, making it impossible for ships at the mouth of the sea fork in China Peninsula to sail into the internal sea through the trench. In Xiaohai and Xincun Bay of Dong 'ao, large-scale cage culture in the bay blocked the inlet and outlet waterways of the bay, resulting in poor seawater supply and serious siltation. Due to the increase of silt and humus in the bay and the decrease of oxygen content in seawater, a large number of serious incidents of fish deaths have occurred many times.

3.5 Destruction of mineral resources

There are abundant mineral resources along the coast of Hainan Island. According to the statistics of existing geological data, the minerals with proven reserves include ilmenite, zircon, monazite and glass sand. Ilmenite, zircon and monazite minerals are mainly distributed in Wenchang, Qionghai, Wanning, Lingshui and the east coast of Sanya. Sand mines for glass are mainly distributed in Danzhou, the Yangtze River and the eastern coast. According to statistics, by the end of 2000, there were 25 ilmenite producing areas in Hainan Province, including 3 large, 9 medium and 3 small 13. Reserves12,826,837 tons (minerals), ranking third in China. The potential value is 654.38+03.34 billion yuan, accounting for 8.27% of the total potential value of all minerals in Hainan Province. There are 28 zircon mineral deposits in China, including 3 large, 6 medium and 9 small/kloc-0. Reserves 1 17648 1 (zircon) tons, ranking second in the country. The potential value is 7.466 billion yuan, accounting for 4.63% of the total potential value of all minerals in Hainan Province. There are 6 monazite mineral producing areas, including 5 types, 1 type. Reserves 12 137 tons (monazite), ranking 16 in China. The potential value is 65 million yuan, accounting for 0.04% of the total potential value of all minerals in Hainan Province. There are 8 glass sand mining areas in China, including 6 large and 2 medium-sized ones. The reserve is 678.85 million tons, ranking 1 in China, with a potential value of 33.943 billion yuan, accounting for 2 1.03% of the total potential value of all minerals in our province. The total potential value of the above four minerals accounts for 33.97% of all minerals in Hainan Province.

The placer of titanium, zirconium and monazite distributed along the coastline of Hainan Island is easy to be mined and selected, which has created good mining conditions and development potential for the development of mining economy in Hainan Province.

Because the seawater farm is built in the depth range of 3 meters from the surface of the ore body to the underground, the mineral resources are destroyed and flooded.

Abundant salt resources have been destroyed. The seawater insolation in Hainan Island is mainly distributed in the southwest and south coast of the island, and there are three salt fields: Yinggehai, Dongfang and Yulin Sub-salt Field. Due to the depression of salt industry, the salt drying field was changed into a seawater farm, which led to a decrease in salt production. At the same time, the sewage discharged from farms pollutes the seawater used for salt drying, which leads to the decline of salt quality.

3.6 Inland migration of coastline

The east and west coasts of Hainan Island are dominated by sandy beaches, and there are sand dikes with different widths and heights along the coastline. In the early days, wild pineapples, shrubs, cacti, coconut trees and Casuarina equisetifolia with well-developed roots grew on the sand embankment, which had good sand fixation and erosion prevention functions. Large coral reefs growing in shallow waters can effectively reduce the direct erosion and erosion of the coast by waves or storm surges and play a role in protecting the coast. Therefore, the early sandy coast has strong anti-invasion ability and is relatively stable, and the coastal sandbars are not easy to collapse. Coastal sandbars and shallow coral reefs together constitute the natural barrier of sandy coast, which makes the sandy coast basically well preserved for a long time and the coastline has not changed much.

In recent years, some sandy coasts have suffered serious erosion and collapse. According to the survey data, Jinshan, Gaolongwan, Lehe, Li 'an, Tengqiao, Meishan, Banqiao and other places with relatively developed marine aquaculture have suffered from different degrees of erosion, with the annual erosion rate ranging from 5 ~ 10m, and some coastal areas reaching more than 10m (Table 8). The main causes of coastal erosion are: in recent years, human activities in the bay have intensified, cage culture in shallow sea and bay area has developed rapidly, and water quality has been polluted, resulting in a large number of coral reefs in shallow sea dying, causing waves (or storm surges) to directly wash the coast and causing the coast to collapse and retreat; In addition, due to the construction of high-level aquaculture ponds, coastal sand dikes were excavated or leveled, causing serious damage. Shelter belts, wild pineapples and shrubs growing on the sandbanks are cut down in large quantities, which makes the coastal sandbanks become loose sand dunes, which makes the coast prone to erosion and collapse, leading to coastal retreat.

Table 8 List of main coastal sections caused by mariculture

4 Suggestions and countermeasures

Hainan Island has a long coastline, many sandy coasts and bays, rich shallow beach resources, abundant sunshine and high water temperature, which has unique geographical conditions for large-scale development of marine aquaculture. While vigorously developing marine aquaculture, we should pay attention to ecological environmental protection and realize the coordinated development of economic construction and environmental protection. This paper puts forward the following suggestions and countermeasures.

(1) Scientific planning and strict control. At present, the marine zoning (planning) of the whole province, Sanya and Wenchang and the development planning of shrimp industry in Wanning are still relatively rough, and many ecological and environmental problems have not been scientifically demonstrated, which can not be used as the final basis for the implementation of shrimp culture planning. So make a detailed plan. In the detailed planning, it is necessary to comprehensively consider the relationship and influence between the present situation and future development of forestry, tourism, ocean, environment, minerals, industry, agriculture, ports and aquaculture, carry out necessary model calculation and analysis, and clearly put forward feasible schemes such as aquaculture layout, wastewater treatment mode, treatment intensity, sewage discharge mode, sewage outlet and water intake location, sludge disposal, wind prevention and sand fixation countermeasures. It is necessary to take Hainan Island as a whole and carry out the environmental impact assessment of mariculture in our province strategically and dynamically, so as to provide technical basis for mariculture planning in our province.

(2) Standardized construction and large-scale development. Actively guide enterprises and rural collectives to carry out large-scale and intensive development of marine shrimp farming, encourage companies and farmers, village collectives and farmers to cooperate and develop, and reduce the disorderly development activities of farmers and self-employed.

(3) It is strictly forbidden to dig ponds for aquaculture in nature reserves and ecologically sensitive areas. Shrimp ponds in nature reserves should resolutely return farmland to forests. Shrimp ponds that pollute drinking water and farmland must be stopped, and those that cannot achieve satisfactory control results must also be returned to forests.

(4) Strengthen law enforcement and supervision, seriously investigate and deal with environmental violations, and expose and warn some cases that damage the ecology when necessary.

(5) Strengthen the supervision of environmental resources. Reasonably arrange the drainage direction of shrimp ponds, and strictly control the discharge of aquaculture wastewater and the total amount and concentration of pollutants. Collect sewage charges in full for aquaculture wastewater. It is necessary to strengthen patrols, mobilize the masses to report, and resolutely stop illegal activities of digging ponds and breeding without authorization.

(6) Strengthen the research and development of seawater shrimp culture technology and improve the pollution prevention and control ability. Guide, encourage and promote the update of aquaculture knowledge and technology, adopt the technology of less water, less medicine, less water change and less discharge, select disease-resistant varieties, and add plant protein to feed to minimize environmental pollution. It is necessary to implement a scientific rotation and polyculture model. Through the rotation of shrimp and crab, the seasonal advantages of high temperature tolerance of shrimp and cold tolerance of blue crab are fully utilized to effectively prevent diseases caused by heavy farming. In addition, when raising blue crabs, Gracilaria is polyculture. On the one hand, Gracilaria is used to decompose and absorb crab excrement and residual feed, which effectively overcomes the problem of water pollution. On the other hand, it can make full use of shrimp ponds and improve the unit output value of shrimp ponds. The introduction of seawater filtration and disease prevention shrimp culture system, the clean seawater after extraction and filtration is used for shrimp culture, which overcomes the shortcomings of high-level shrimp culture and seawater plus fresh water shrimp culture, such as environmental pollution, long shrimp culture cycle and low economic benefit.

(7) Strengthen product quality assurance in the whole process of aquaculture and guide the development of green seafood.

(8) Strengthen public participation and publicity. Strengthen public participation in ecological protection, accept public supervision, especially for seawater shrimp farming projects involving farmers' land and other vital interests, rationally distribute benefits through extensive and effective public participation, reduce negative impacts, and promote the sustainable development of regional social economy. At the same time, strengthen publicity and education, constantly enhance the concept of sustainable development of the broad masses of cadres and people, and improve people's awareness of legal system and ecological environment protection.

refer to

[1] Pang Yichun, et al. Comprehensive investigation of coastal zone and tidal flat resources in Guangdong province: engineering geological report of Hainan Island. Geological and Mineral Team of Guangdong Coastal Zone and Tidal Flat Resources Comprehensive Investigation Brigade, 1986.

[2] Pang Yichun et al. Report on Coastal Hydrogeology of Hainan Island in Comprehensive Investigation of Coastal Zone and Tidal Flat Resources in Guangdong Province. Geological and Mineral Professional Team of Guangdong Comprehensive Investigation Brigade of Coastal Zone and Tidal Flat Resources, 1986.

Zhao Daying, Hua Lin, et al. Investigation report on eco-environmental geology of coastal zone of Hainan Island. Hainan Institute of Hydrogeology and Engineering Geology, 2004

[4] Yue Ping, Fu. Investigation report on the present situation of ecological environment in the coastal zone (typical region) of Hainan Island. Hainan Provincial Department of Land and Resources, 2002

Influence of mariculture on geological environment in coastal zone of Hainan Island

Xu Zhongsheng, Xue Guicheng, Xia Changjian

(Hainan Geological Survey Institute, Haikou 570206)

Abstract: Hainan Island is rich in tidal flat resources, and it has unique advantages to develop mariculture. Based on the development conditions, economic benefits, breeding methods and development trends of mariculture in the coastal areas of Hainan Island, this paper analyzes the environmental geological problems brought by mariculture and its harm to Korean pine forest and green bark forest. This paper studies the causes of coastal defense forest destruction, coastal environmental pollution (seawater pollution, groundwater pollution and salinization), soil erosion and land wasteland melting (desertification), port siltation, land salinization, coastal erosion and mineral and tourism resources destruction caused by mariculture, and puts forward some suggestions and corresponding countermeasures for the coordinated development of mariculture and environmental protection.

Keywords: coastal tape; Mariculture; Geological environment; environmental protection