Geological environmental conditions

Qingdao is located at the southwestern tip of Shandong Peninsula, bordering on the Yellow Sea in the southeast, Weifang and Yantai in the west and north, and Rizhao in the southwest, and is located at119 26' 24 "~120 57' 36" in east longitude and 35 34'12 "in north latitude. It has jurisdiction over seven districts (Shinan, Shibei, Sifang, Licang, Laoshan, Chengyang and Huangdao) and five county-level cities (Jimo, Jiaozhou, Laixi, Pingdu and Jiaonan). The total land area of the city is 10654km2, and the coastline is 730km long.

In the long geological history, different landforms such as mountains, hills, plains, rivers, lakes and oceans have been formed through various forms of crustal movement and geological forces. After weathering, denudation and transportation, different lithologic strata were deposited in different sedimentary environments, forming different soils and creating a unique geological environment background in this area.

I. Topography

The overall terrain of Qingdao is characterized by the uplift of the north and south wings, high in the east and low in the west, and low in the middle. There are three mountain systems in the area: Laoshan Mountain in the southeast, with the main peak at an altitude of 1 132.7m, and the mountain is steep, reaching southwest of Qingdao in the north and northeast of jimo city, making it the third peak in Shandong Province; Dazeshan mountain range is in the north, with the main peak at an altitude of 736.7 meters; Jiaonan Mountain range consists of Dazhu Mountain, Zhuxiao Mountain and Tiekan Mountain in the southwest, with the main peak at an altitude of 724.9 meters ... Jiaolai Basin is located between mountain systems, with low terrain and generally less than 50 meters above sea level, and Quaternary loose deposits are mainly distributed in various river valleys. The hilly area in the area is 4950km2, accounting for 46.46% of the total land area. Plain depression 5620km2, accounting for 52.75%; Other 84km2, accounting for 0.79%.

According to its genetic types and morphological characteristics, the landforms in this area can be divided into four categories: denuded structural landforms, structural denuded landforms, denuded accumulated landforms and accumulated landforms (Figure 12- 1).

Second, meteorology and hydrology.

1. Meteorological

Qingdao belongs to the continental climate of warm temperate monsoon in North China. Due to the influence and adjustment of the marine environment, it has obvious maritime climate characteristics, humid air, mild climate, more rainfall and distinct seasons, with the characteristics of cool in summer at the end of spring, cool in autumn and long in winter. According to the statistics of meteorological observation data in Qingdao in the past hundred years, the average annual precipitation in Qingdao is 677.95 mm (1898 ~ 2002) and 647.8 mm (1996 ~ 2002). The precipitation is unevenly distributed in each season of the year, and the flood season (June ~ September) accounts for 70% ~ 76%. The annual precipitation changes greatly, and the drought year series lasts for a long time. The maximum value is closer to the minimum value 1000mm, and the ratio is generally 3 ~ 4 times. Geographically, there is a decreasing trend from coastal to inland, and there is vertical zoning in mountainous areas, which decreases from high to low. 2002 is a particularly dry year once in 50 years, with an annual precipitation of only 463.8 mm. ..

Figure 12- 1 Qingdao Landform Type Map

The average annual evaporation in Qingdao is 14 10mm, and the highest monthly average is 175mm in May. The evaporation in inland areas is greater than that in offshore areas.

2. Hydrology

Qingdao * * * has 224 large and small rivers, and 33 rivers with basin area greater than 100km2. According to the division of river basins, it can be divided into three major river systems: Dagu River, Beijiaolai River and coastal rivers. Dagu River originated in Fushan, Zhaoyuan City, and merged 500 meters north of Daozibo Village, Laixi City. It flows through Laixi City, pingdu city, jimo city, jiaozhou city and Chengyang District, and enters Jiaozhou Bay in the south of Matou Village, Fang Ying Town, jiaozhou city. The total length of the main stream is 179.9km, the drainage area is 13 1.3 km2, and the drainage area of Qingdao is 4850.7km2. The source of Beijiaolai River is located at the northern foot of the watershed in Yaojia Village, Zhaike Township, pingdu city, and flows from southeast to northwest along the border between pingdu city and gaomi city and Changyi City. It flows into Laizhou Bay at Damiaojia, xinhe town, with a total length of 100km and a drainage area of 3978.6km2 The drainage area of Qingdao is1914.0km2. The main tributaries are Zehe River, Wanglonghe River, Xianhe River and Baisha River. The larger rivers that flow into the sea alone from coastal rivers are Baisha River, Chengyang River (called Mohe River in Jimo), Yanghe River, Zhuanghe River in Wang Ge (Fenghe River), Baima-Liji River and Zhoutuan River (Lianyin River).

There are 3 large reservoirs and 2 1 medium reservoirs in Qingdao, among which the larger reservoirs are: Chanzhi Reservoir, Yin Fu Reservoir, Jihongtan Reservoir and Laoshan Reservoir.

Three. General situation of regional geology

1. Formation lithology

In addition to the Quaternary loose strata, the exposed strata in Qingdao are mainly Mesozoic Cretaceous and Proterozoic metamorphic rock series, and the Tertiary is concealed strata. Now briefly described as follows:

(1) Proterozoic

Jingshan Group (Pt 1J) and Fenzishan Group (Pt 1F) are mainly exposed.

Jingshan Group is mainly distributed in Nanshu Town, Laixi, Mingcun Town, pingdu city, Yunshan Town and Wangtai Town, Jiaonan City. It belongs to amphibolite-amphibolite facies metamorphism, and the main lithology is marble, biotite granulite, feldspar quartzite, granulite, amphibole, diopside, graphite granulite and gneiss.

Fenzishan Group is mainly distributed in Huibu, Pingdu, and belongs to high greenschist facies-low amphibolite facies metamorphism. The lithology is mainly biotite granulite, amphibole, granulite, feldspar quartzite and tremolite marble.

(2) Mesozoic Cretaceous (K)

From old to new, it is divided into Laiyang Group (), Qingshan Group () and Wangqun (KW), which are widely distributed in the central subsidence area of this area.

Laiyang Group is mainly distributed in Jiaozhou, Jiaonan and Jimo. It is a set of continental coarse clastic-fine clastic alluvial facies-river facies-river facies, which consists of conglomerate, sandstone, siltstone, feldspathic sandstone and gravelly medium-grained lithic sandstone.

Qingshan Group is mainly distributed in Jiaozhou, Hetao, Hongdao, Louzituan-Fengcheng, Laixi and Lingshan Weizhen. It is a set of intermediate-basic-neutral-acidic volcanic rocks with continental volcanic eruption facies and overflow facies, and the lower lithology is ignimbrite with rhyolitic breccia and lithic glass tuff. The lithology in the middle part is andesite, basaltic andesite mixed with andesite volcanic breccia, breccia mass, etc. The upper part is basaltic coarse andesite mixed with gravel.

Wang Group is mainly distributed in the vast area from the north of Shangma Town in jiaozhou city to Guxian and Laixi. It is a set of continental purplish red clastic rocks with basalt deposits. The lithology of the lower part is calcareous argillaceous siltstone, mixed with calcareous fine-grained feldspathic sandstone and fine-grained feldspathic sandstone, and the upper part is almond basalt, tholeiite basalt and Dingyi petrochemical andesite basalt.

(3) New generation

The Paleogene Wutu Formation is mainly concealed in Pingdu South Dawa, which is composed of conglomerate, sandstone, shale and argillaceous rock.

The Quaternary system is widely distributed on the banks of modern rivers, in front of mountains, at sea and in quasi-plain areas. It is a loose accumulation layer of alluvial deposits, alluvial deposits, residual slope deposits, marine deposits, alternating accumulation of land and sea and artificial accumulation of Pleistocene-Holocene. Among them, the water supply to proluvial is the most significant, mainly distributed in the middle and lower reaches of major rivers and piedmont areas, with a thickness of 10~20m ~ 20m and a maximum thickness of 25 ~ 30m. There are many double-layer structures, the upper part is clayey sand and sandy clay, and the lower part is sand and gravel layers with different particle sizes, including argillaceous interlayer, and the edge zone is wedged into proluvial, so the structure is complicated. The smaller the river, the thinner the sand layer, the worse the separation and the greater the phase change. The upper reaches are granite distribution areas with coarse sand grains. Near estuaries and offshore depressions, there are often marine sedimentary interlayers in alluvium, and the lithology is silt, muddy clay, muddy sand and so on. The thickness is generally less than 5m.

The intrusive rocks in Qingdao are mainly developed in Neoproterozoic Jinning period, Sinian period and late Mesozoic Yanshan period, which can be merged into seven units and mainly distributed in Laoshan, Dazeshan and Dazhushan.

2. Geological structure

Qingdao is located in two tertiary structural units, Ludong Uplift and Jiaolai Depression in the northeast of Rizhao Uplift in Jiaonan-Wen Wei orogenic belt on the southern margin of North China plate. The main structural features in the area are fold structure, ductile shear zone and brittle fracture structure, and the main strike is ne, followed by NE and EW. The brittle fracture structure in this area has the function of controlling water and its direction is complex. Except for some ancient fault structures, most of them were formed in the late Yanshan period, which is the result of the combined action of horizontal compressive stress in the northwest-southeast direction and horizontal pressure caused by vertical uplift. They have the characteristics of multi-stage activity, and can be summarized into four groups of yoke fault structural systems: ① nearly east-west (75 ~ 85) and nearly north-south (5. ② NE (55 ~ 65) and NNW (330 ~ 340); ③ NE (20 ~ 25) and NWW (290 ~ 300); ④ Northeast (30 ~ 45) and northwest (300 ~ 320). Among them, the mechanical properties in NE, NNE and NE directions are mostly compressive and torsional, and the corresponding yoke fractures are mostly tensile.

Four. General situation of regional hydrogeology

1. Division of water-bearing rock groups and occurrence conditions of groundwater

According to the different hydrogeological characteristics, groundwater in Qingdao can be divided into various water-bearing rock groups, such as loose rock pore water, clastic rock pore fissure water, gushing rock pore fissure water, carbonate rock karst fissure water and massive and layered rock fissure water, among which loose rock pore fissure water is the main water-bearing rock group with strong water supply capacity.

Loose rock pore water-bearing strata: mainly distributed in Dagu River, Baisha River-Chengyang River, Baima River-Liji River, Wang Ge Zhuanghe River, Yanghe River, Zhoutuan River, Zhang Cun-Licun River valley plain and piedmont plain in the southwest of Daze Mountain. The water-bearing strata are mainly composed of sand and gravel with different particle sizes in Quaternary proluvial, and the thickness is generally 5 ~ 65438+. The water yield of a single well can reach above 1000 m3/d, and the buried depth of water level is generally 2 ~ 4m. The hydraulic property is basically pore diving, and the bearing capacity of some areas is weak at high water level. Dagu River and Baisha River-Chengyang River are important water supply sources in Qingdao, and the other river basins are the main local water supply sources.

Carbonate karst fissure water-bearing strata: mainly distributed in Pingdu and Laixi, with a small amount distributed in Wangtai, Jiaonan. The water-bearing strata are the marble of Fenzishan Group, which generally occur in other metamorphic rocks in the form of interlayer or lens, with impure structure, mostly serpentine marble, dolomite marble and diopside marble. The fractures are well developed, and the depth is generally limited to 100m, which is rich in karst fissure water, especially in areas with good structural and geomorphological conditions. The water output of a single well is generally greater than 500m3/d, and the maximum is greater than 1000m3/d, so the water quality is good. However, due to the small distribution area, the water supply is limited.

Water-bearing rock strata that spew out pore fissure water: mainly distributed in Jimo, Jiaozhou, Laixi and Chengyang. The water-bearing rocks are basalts of Qingshan Group and Wangshi Group, with well-developed pores and fractures, generally buried at a depth of 30-50m, with strong water yield, and the water output of a single well is 500- 1000m3/d, with good water quality and often containing trace elements (such as Sr) beneficial to human body.

Clastic pore fissure water-bearing strata: mainly distributed in Jiaozhou, Jimo, Laixi and other places. The water-bearing strata are Cretaceous Laiyang Formation, Wangshi Formation sandstone, sand shale and tuffaceous sand shale. Due to the undeveloped pores and fractures, the water permeability and water abundance are very weak, and the water output of a single well is generally less than 50m3/d, so the water supply is of little significance.

Massive and layered fractured water-bearing strata: mainly distributed in Laoshan, Dazeshan and Jiaonan, and the water-bearing strata are granite, granodiorite, gneiss, granulite and schist. Weathered zone is generally less than 30m in depth, with weak water yield, and the water yield of a single well is less than 30m3/d, and the local structural fracture-intensive zone is relatively rich in water. The water yield of a single well can reach more than1100m3/d, and the highest can reach 500m3/d, but the distribution is extremely uneven, and only local water supply can be provided.

2. Groundwater recharge, runoff and discharge conditions

The groundwater in Qingdao is mainly the shallow pore water of Quaternary loose rocks, and there is a small amount of vein-like structural fissure water in some areas. Atmospheric precipitation is the main source of recharge, and the movement direction of groundwater is basically consistent with topographic slope and surface water system. Atmospheric precipitation, surface water and groundwater are closely related, and the transformation relationship is obvious.

Judging from the regional hydrogeological zoning, this area belongs to the low hill hydrogeological area in eastern Shandong (Ⅲ). Considering factors such as geology, structure, landform and groundwater characteristics, it can be divided into three hydrogeological subregions, namely, the hydrogeological subregion of Jiaobei low hilly region, Jiaolai basin and Laoshan-Jiaonan middle and low hilly region (Figure 12-2).

(1) Hydrogeological Sub-region of Jiaobei Hilly Area (Ⅲ1)

It is mainly distributed in Pingdu and Laixi areas in the north of Qingdao, belonging to the western section of Jiaobei uplift. The landform is low mountains and hills, and the terrain gradually decreases from north to south. It is mainly composed of Yanshanian granitoids and ancient metamorphic rock series, with Quaternary accumulation in intermountain valleys, which can be further divided into: ① granite fissure water community in Dazeshan; ② karst fissure water area of Pingdu-Laixi metamorphic rock; ③ fissure water community in Laixi metamorphic rocks; ④ Quaternary pore water community in intermountain valley.

(2) Hydrogeological subregion of Jiaolai Basin (Ⅲ 2)

Mainly distributed in most areas of Pingdu, Laixi, Jiaozhou and Jimo. The geological structure unit belongs to Jiaolai depression, and the landform is valley plain, piedmont plain and denudation plain. The strata are mainly Quaternary alluvial, alluvial and diluvial, Cretaceous clastic rocks and volcanic rocks. Because of its low terrain, it is conducive to the accumulation of groundwater and has good storage conditions. It is the most abundant area of groundwater in Qingdao. This area not only receives direct infiltration recharge from atmospheric precipitation, but also receives surface water and groundwater recharge from other adjacent hydrogeological sub-regions, especially quaternary pore water and basalt pore fissure water in valley plain and piedmont plain, with thick aquifer, large water storage space, strong surface permeability and favorable recharge conditions, making it the most abundant groundwater area in this area. The main ways of groundwater discharge in this area are runoff, artificial mining and evaporation, among which artificial mining is the main way of groundwater discharge. Runoff first flows northward into Laizhou Bay through Beijiaolai River; Second, it gathers in Dagu River and discharges southward to Jiaozhou Bay. However, due to the gentle terrain, small hydraulic gradient, slow runoff and poor drainage. Due to a large number of groundwater exploitation, the buried depth of water level increases and the evaporation flow decreases gradually.

(3) Hydrogeological Sub-region of Jiaonan-Laoshan Middle and Low Mountains (Ⅲ 3)

Mainly distributed in Jiaonan and Laoshan, it is the northeast section of Jiaonan uplift, with low mountains and hills, high terrain and large slope, which are inclined to the northwest and southeast coast of Jiaolai Basin respectively. The lithology is mainly Yanshanian granitoids. In addition, the Quaternary system in the middle and lower reaches of several rivers is relatively developed, forming valley plains of different sizes.

Atmospheric precipitation is almost the only recharge source of bedrock fissure water in the hydrogeological subregion of Jiaobei and Jiaonan low mountains and hills. However, due to the steep hillside and undeveloped cracks, most of the precipitation is converted into surface runoff, which is collected in the hydrogeological subregion of the ocean and Jiaolai basin. A small amount of precipitation seeps into the ground and is converted into groundwater, which is quickly discharged into nearby valleys in the form of falling springs or underground runoff. The valleys and streams in the mountains become the main channels for collecting and discharging groundwater. Due to the shallow development depth of fractures and large hydraulic gradient, the alternating circulation of groundwater is strong. The smaller valley plains in this area, such as the valley plains in the middle and lower reaches of Zhuanghe River in Wang Ge, have similar recharge, runoff and discharge characteristics with the hydrogeological subregion of Jiaolai Basin. Only in areas with low groundwater development, such as the valley plains in the middle and lower reaches of Baima-Li Ji, can phreatic evaporation not be ignored.

3. Groundwater hydrochemical characteristics

Groundwater in Qingdao is mainly land dissolved filtrate, and offshore depressions and estuaries are marine and land-sea sedimentary water. The hydrochemical characteristics in its natural state are as follows: the periphery of this area is surrounded by the sea on three sides, and during the transformation of precipitation, surface water, groundwater and seawater, the Cl- content in groundwater is high due to the evaporation of seawater; The distribution of surface water and groundwater in the area is basically the same, and they all flow into the sea from hills through plains. In the process of runoff, the mineral composition of stratum medium is relatively stable and its solubility is poor. The specific environment makes the chemical characteristics of groundwater have obvious zonation: from hills to plains to coastal depressions, the hydrochemical types range from HCO3-Ca type with good water quality to →HCO3 Cl-Ca or Ca Mg, Ca Na type to CL. 0.5g/l → 0.5 ~1.0g/l → > 1g/L； Affected by geochemical environment, there are some primary inferior water in the area, such as high fluorine area in calcareous nodule distribution zone, coastal zone and offshore depression, salt water area in water storage zone, etc.

Figure 12-2 Hydrogeological Zoning Map of Qingdao

Verb (abbreviation of verb) the characteristics of environmental geological zoning

According to the influence of topography, meteorology, hydrology, geology, hydrogeology, vegetation soil and other factors on the regional geological environment characteristics, Qingdao can be divided into four geological environment areas (Figure 12-3).

1. Geological environment area of middle and low mountains and hills

The area is mainly distributed in Laoshan, Zhushan, Tiekan Mountain, Daze Mountain and other hilly areas. Its landform genetic type belongs to denudation structure-structural denudation landform, which has been denuded and cut for a long time. The ground elevation is generally above 50m, and the cutting depth varies. Basement rocks are mainly composed of granite, followed by sand shale and volcanic rocks. The surface rocks are exposed, and the sediments at the bottom of the valley are developed, but the thickness is not large.

The Laoshan rock mass is composed of Laoshan granite in the late Yanshanian period, with a cutting depth of more than 500m m. Besides granite, there are schists, gneiss and marble in Xiaozhushan and Dazeshan, with a cutting depth of 200 ~ 400 m. The granite rocks in the middle and low mountains are hard, with steep mountain slopes and undeveloped rock cracks. Due to the steep slope of the ground, deep gully cutting, steep hillside, and a lot of atmospheric precipitation (except in Dazeshan area, which is more than 700mm), the strongly weathered zone is undeveloped, and the weathering depth is generally less than 3 m. Most of the precipitation is rapidly discharged downstream from the surface, and a few of it seeps into the ground and is discharged by spring water or underground runoff, so the water-rich property of the rock mass is poor.

The vegetation in the middle and low mountainous areas is well developed, mainly distributed in dense forest areas and general forest areas, with less human activities and man-made pollutants, weak rock weathering and groundwater dissolution, and strong groundwater alternation. Although the groundwater is poor in water abundance, its salt content is low and its water quality is good. Mineral water is mostly distributed in the zone with dense structural fractures.

The hilly area is mainly the residual veins of the above-mentioned mountains, and there are many exposed rocks on the surface, such as granite, gneiss, volcanic rocks, sand shale and so on. The mountain is steep and round, the cracks in rock mass are well developed, and a small part of it is covered with vegetation, which is mainly distributed in general forest areas and sparse forest areas. Atmospheric precipitation is generally greater than 600 mm, and there are thin eluvial layers in the canyon. Most of the atmospheric precipitation is discharged downstream in the form of torrent, and some of it is discharged through cracks or thin overburden (gravel soil and sand).

Due to weathering and human activities, water alternation in hilly areas is more conducive to water and salt chemistry than in middle and low mountainous areas, resulting in higher salt content in groundwater than in low mountainous areas. In urban areas and near towns, because there are many industrial and domestic pollution sources, pollution plays a control role in groundwater quality, and the chemical composition of water often appears abnormal, with many components exceeding the standard. The salinity can reach 1.0 ~ 1.5g/L, and the local salinity is greater than 1.5g/L.

2. The denudation of quasi-plain geological environment area

Widely distributed in Jiaozhou, Jimo and Laixi areas of Jiaolai Basin, the landform is denuded quasi-plain, with gentle ridges and slopes, and the relative elevation is less than 20m, generally less than 50m. Lithology is mainly Mesozoic Cretaceous clastic rocks and volcanic rocks. There are thin eluvial deposits on the surface of low-lying areas, the thickness of which is generally less than 5m, and many bedrock are exposed in the mountains. Most of the rest is covered by a thin layer of residual slope gravel, sand and silt. Vegetation is relatively developed, mainly cultivated land, with poor soil quality, poor surface filtration and purification protection, and atmospheric precipitation and pollutants are easy to penetrate into the ground.

Rock fractures are developed in this area, mostly shallow weathered fractures and volcanic caves. Because of the existence of clay, some cracks are bridged and filled, and the space capacity of cracks is small, and the connectivity of caves is poor, resulting in poor water yield and shallow groundwater burial. Due to small topographic relief, slow surface runoff, poor water alternation and dynamic conditions, long water-salt interaction time, and surface pollution, the salinity of groundwater is high, and the salinity is generally 0.5 ~1.0g/L.

3. Geological environment area of alluvial-diluvial plain

It is distributed in the piedmont and the middle and lower reaches of rivers, mainly in the middle and lower reaches of Dagu River, Baisha River-Chengyang River, alluvial plain of Beijiaolai River, Zhuanghe River in Wang Ge, Jiaonan and Baima-Li Ji Valley Plain. The landform types are piedmont alluvial plain and valley alluvial plain, and the terrain is relatively flat and slightly undulating. The sediments are mainly loose silty clay, silt, medium-coarse sand and gravel layer, which are formed by river alluvial and alluvial sediments. Generally, it is a double-layer structure, with silty clay and silt at the upper part and medium-coarse sand and gravel at the lower part. The lower part is the water level of the main aquifer, with a thickness of 5 ~ 15m and a local area of 25m, with abundant water, and the buried depth of the water level is generally 2 ~ 4m, with a maximum of 10m. The lithology of vadose zone is mainly silt and silty clay.

Figure 12-3 Geological Environment Zoning Map of Qingdao

The atmospheric precipitation in this area is about 500mm except in Pingdu North Jiaolai River area, and most of the other areas are about 600mm, and the surface runoff is slow. The vegetation in the area is well developed, mainly cultivated land, with good soil quality and strong filtration and purification ability of the surface soil. Quaternary pore water is mainly supplied by atmospheric precipitation infiltration, but also by bedrock fissure water and river water infiltration in front of the mountain. Groundwater is mainly discharged through evaporation, exploitation and downstream runoff. However, this area is the main production and living activity area, and domestic pollution, industrial pollution and agricultural pollution have gone beyond the scope of "point pollution" and formed a through pollution layer (area). The movement and alternation of groundwater in this area is slow, and the water is in full contact with loose rocks, and the chemical interaction between them is strong. Coupled with the participation of pollutants and the influence of artificial mining, the chemical composition and concentration of groundwater change obviously from the upstream piedmont zone to the downstream coastal zone, and there is obvious hydrochemical zoning phenomenon. The salt content of groundwater varies from 0.5g/L in front of the mountain to 65438 0.5g/L in coastal areas, and it can reach more than 3g/L in areas with serious seawater intrusion.

4. Coastal plain geological environment area

It is mainly distributed in the narrow strip near the estuary of coastal rivers, with flat terrain and coastal plains. The sediments are mainly composed of fine sand, silt and marine silt, with poor water abundance. Stratum is formed under the interaction between land and sea, and groundwater is formed in the competition between seawater and mainland fresh water, and the water level is shallow. The atmospheric precipitation in this area is generally above 700mm, most of which is scattered surface water flowing directly into the sea, and a small part of which seeps into groundwater. The soil is mostly salinized or swampy, and the vegetation is poorly developed, mostly salt-tolerant weeds. Estuary is often a concentrated discharge and collection area of pollutants, which is seriously polluted. Other areas are mostly salt fields. Due to the influence of tides and underlying marine strata, the groundwater quality in this area is extremely poor and its chemical composition is extremely complicated. The hydrochemical type is mainly Cl-Na type, and the salinity is generally greater than 3 ~ 5g/L, and greater than 10g/L near Yantian.