The monitoring results show that:
The monitoring results of marine environment in our city in 2115 show that the area of seriously polluted sea area in coastal waters is 4,131 square kilometers, and that of moderately polluted sea area is 2,396 square kilometers. The overall marine environmental quality in Zhoushan sea area is similar to last year, but the area of seriously polluted sea area has declined.
The main factors exceeding the standard in seawater are nutrients, and some stations slightly exceed the standard in petroleum.
in 2115, the quality of surface sediments in Zhoushan coastal waters was good, and all the indexes met the first-class marine sediment quality standard except that the heavy metal copper exceeded the standard in some stations.
in 2115, the sanitary quality of economic shellfish in some coastal areas of Zhoushan city was acceptable; In the economic shellfish (mussel, SINONOVACULA constricta, oogway, oyster, etc.) sampled and tested, except for a little residue of heavy metals such as lead, cadmium and DDTs, all the other indicators meet the first-class marine biological quality standard.
Red tide disasters occur frequently.
in 2115, there were 11 red tides in * * *, with a cumulative area of over 11111 square kilometers.
with the economic development of Zhoushan city, the environmental quality of the inshore and offshore waters is not optimistic, and the discharge capacity of various pollutants will not be significantly reduced in the near future.
therefore, it is necessary to strengthen the monitoring and remediation of the marine environment in the sea area under the jurisdiction of Zhoushan city, so as to serve government departments at all levels in formulating marine environmental management policies, determining marine environmental management objectives, reducing marine disasters and adjusting economic structure.
At the same time, we also hope that all levels of government departments and the public in our city will continue to pay close attention to the marine environment in Zhoushan, protect the marine environment while developing and utilizing marine resources, ensure the stability, diversity and integrity of marine ecosystem, and ensure the sustainable utilization of marine resources and the sustainable development of marine economy.
2. Status and trend of marine environmental quality in Zhoushan City
2.1 Pollution into the sea
Pollution from big rivers
In 2115, the total amount of pollutants carried into the sea by major rivers such as Yangtze River, Qiantang River and Yongjiang River near Zhoushan Sea remained at a high level, and the main pollutants were about 6.17 million tons, of which COD was 5.9 million tons, accounting for 95.8% of the total; 1.9 million tons of nutrients, accounting for about 3.1% of the total; 39,111 tons of petroleum.
Land-based pollution into the sea
According to the statistical yearbook, the total amount of wastewater discharged by our city in 2114 was 21.18 million tons, including 11.38 million tons of industrial wastewater and 4711 tons of industrial solid waste.
pollution from marine sources into the sea
in 2115, the area of mariculture in our city was 9,397 hectares, a decrease of 1.5% compared with the previous year, and the output of mariculture was 115,411 tons, a decrease of 8.6% compared with the previous year.
with the reduction of mariculture area in the coastal waters of our city and the promotion of pollution-free production, the pollutants produced by mariculture itself are decreasing.
The mobile pollution sources at sea include the sewage discharged by merchants, cargoes and fishing boats, and the main types of pollutants are waste oil, waste gas, ballast water, domestic garbage and sewage.
according to preliminary statistics, by the end of 2115, the number of marine motorized fishing boats in our city had reached 9,113, with a total power of 1,369,911 kilowatts and a fishing workforce of 99,956.
2.2 Quality of marine environment
The monitoring results of marine environment in our city in 2115 show that the overall quality of marine environment in Zhoushan sea area is similar to that of last year, but the area of seriously polluted sea area has decreased; Nutrients in seawater exceeded the standard seriously, and petroleum exceeded the standard in different degrees. All other monitoring indexes met the second-class seawater quality standard.
Zhoushan sea area is 4131 square kilometers with serious pollution, 2396 square kilometers with moderate pollution, 2167 square kilometers with slight pollution, 2713 square kilometers with clean sea area and 9423 square kilometers with clean sea area.
inorganic nitrogen
in Zhoushan sea area, the average content of inorganic nitrogen exceeds the four kinds of seawater quality standards, and the exceeding multiple is 1.77.
The waters near Shengsi Archipelago, Daishan, Qushan Island and Zhoushan Island are all seriously polluted waters, and their average contents are 2.27 times, 1.47 times and 1.33 times higher than the four kinds of seawater quality standards respectively.
compared with the previous year, the content of inorganic nitrogen in the waters near Shengsi Archipelago has increased, while the content of inorganic nitrogen in the waters near Daishan, Qushan Island and Zhoushan Island has decreased. The data shows that the discharge of pollutants from the Yangtze River is increasing.
active phosphate
the average content of active phosphate in Zhoushan sea area is relatively clean except that the sea area near Zhoushan Island is slightly and moderately polluted.
The average standard indexes of active phosphate in the waters near Shengsi Archipelago, Daishan, Qushan Island and Zhoushan Island are 1.41, 1.71 and 2.13, respectively, and the degree of phosphate pollution is reduced compared with last year.
petroleum
The average content of petroleum in Zhoushan sea area has increased compared with last year, which belongs to lightly polluted sea area.
its average content basically meets the first-class seawater quality standard, but the oil in the sea area near Zhoushan Island slightly exceeds the standard, with the exceeding multiple of 1.94.
The data show that the oil pollution in Zhoushan sea area is aggravated with the new construction and expansion of oil depots and oil terminals on Zhoushan island and nearby islands, and the increase of oil import, export, storage and transportation.
2.3 quality of marine sediments
in 2115, the surface sediments in Zhoushan coastal waters were of good quality, and the indicators such as petroleum, sulfide, organic carbon, mercury, cadmium, lead, arsenic, 666 and DDTs all met the first-class quality standard of marine sediments, while the heavy metal copper slightly exceeded the standard in some stations.
Heavy metal copper exceeded the standard in some stations, with the maximum standard index of 1.28 and the over-standard rate of 75%.
2.4 marine biological quality
In 2115, the economic shellfish (mussels, SINONOVACULA SINONOVACULA, Oysters, etc.) along the coast of Zhoushan City were sampled and tested. The results showed that the heavy metal lead in the economic shellfish in Zhoushan City exceeded the first-class marine biological quality standard, while cadmium and DDTs remained slightly, and other indicators met the first-class marine biological quality standard.
compared with 2114, the biomass has improved (table 3).
table 3 main over-standard factors of economic shellfish in Zhoushan city in different years
main over-standard factors in investigation years
no DDT in 2112
petroleum hydrocarbons, heavy metals such as lead, arsenic and DDT in 2114
heavy metals such as lead, cadmium and DDT in 2115
Sijiao and Shengshan.
The content of cadmium in economic shellfish in Sijiao, Shengshan, Gaoting, Liuheng and other areas slightly exceeded the standard, and the standard index was between 1.91 and 6.85. In other areas, it meets the first-class quality standard of marine life.
DDT exceeded the standard in Sijiao, Shengshan, Dongsha, Liuheng and other sea areas, with standard indexes ranging from 1.17 to 2.41.
3. Marine disasters and marine fouling events
3.1 Red tide disaster
In 2115, the red tide disaster in the East China Sea was serious, and Zhoushan was also one of the hardest hit areas.
There were 11 red tides in Zhoushan sea area in the whole year, with a cumulative area of over 11,111 square kilometers, nearly double the previous year, the highest in the last five years; At the same time, new dominant species have emerged (such as karenium miconioides, Thalassiosphaera rotundus, etc.); May to June is the frequent period of red tides in Zhoushan sea area (see Table 4).
The dominant species of red tide this year are Skeletonema costatum, Prorocentrum dantatum, Karenia mikimotoi, etc. There is no abnormal phenomenon of cultured organisms in the red tide occurrence area. The shellfish poisoning of fish and shellfish in the red tide occurrence areas such as Zhongjieshan, Shengshan, Zhujiajian Island, Taohua Island and the nearby waters was detected, and all the organisms were found.
Table 4 List of Red Tide in Zhoushan Sea Area in 2115
Time and place of occurrence (km2) Red Tide Organism
1 6.1 is in the sea area near Shengshan Island southwest to
Dachang Tu Shan East, 122 41.1' E,
31 28.1' N ~
122 31.
31 17.3 ′ n about 4111km2 Gymnodinium Nagasaki
Prorocentrum dentatum
2 6.2-6.3 Zhongjieshan Archipelago to
122 37.6 ′ e,
31 15.5 ′ n ~
122 42.
31 29.9 ′ n is about 6111km2
(inter-provincial) Gyrocentrum Nagasaki
Prorocentrum dentatum
Skeletonema costatum
Chaetoceros aggregatum
3 6.4. 122 15.1 ′ e,
31 11.9 ′ n is about 1111km2
(inter-provincial), Skeletonema costatum
4 6.5 from the north of Huaniao Mountain to
122 44.9 ′ e near the Yangtze River estuary,
31 11.5 ′ n ~
.
31 31.1 ′ n is about 2711km2
(inter-provincial), Skeletonema costatum
Gyrocentrum Nagasaki
Prorocentrum dentatum
5 6.16 Daishan, Shengsi Majishan, Shengshan, Huaniao Mountain, Langgang Islands, Shengshan Mountain, etc. 31 37 ′ n, 122 31 ′ e, 29 59 ′ n and other sea areas from 11 km2 to 331 km2. Skeletonema costatum
Prorocentrum dentatum
3.2 storm surges
There are mainly three storm surges along Zhoushan coast this year, which were respectively affected by typhoon Mai Sha (1519
Among them, Typhoon Mai Sha landed in Yuhuan, Taizhou, Zhejiang Province on August 5, Typhoon Kanu landed in Jiaojiang, Taizhou, Zhejiang Province on September 11, and Typhoon Caidie turned in the open sea.
All three typhoons have brought great tidal water increase to Zhoushan coastal area. Due to the influence of typhoons Mai Sha and Caidie, it coincided with astronomical tide, and Zhoushan Ocean Station (shenjiamen) and Daishan Ocean Station both exceeded the local warning water level by * *, while typhoon Kanu coincided with astronomical tide. Although it had great influence, it did not exceed the warning water level by * * *.
annual extreme value * * * position: Zhoushan Ocean Station extreme value * * position is 276cm(85 Yellow Sea base, the same below), which appeared on September 5; The extreme value of Daishan Ocean Station is 242cm, which appeared on September 5. The extreme values of the two stations both appeared during the typhoon "Butterfly".
3.3 disastrous waves
In 2115, the number of days when there were waves of more than 4 meters in Zhoushan coastal area and adjacent sea areas was 21 days, which was obviously more than normal, including 11 days affected by typhoon, 8 days affected by cold air and 3 days affected by both.
3.4 marine fouling incident
On February 25th, the ship "Ningda 1" collided with the anchored ship "Yunhong 7" at Wukuishan anchorage in Zhoushan, Zhejiang Province, and the cargo hold was damaged, with an oil spill of about 1.5 tons.
On September 23rd, Huajie No.6 spilled 1.25kg of fuel oil from the vent pipe in the sea area of Mazhi anchorage in Zhoushan, Zhejiang Province.
4. Environmental status of marine functional area
4.1 Environmental status of marine aquaculture area
Shengsi marine aquaculture area
From April to September, 2115, seven monitoring stations were set up in Shengsi marine aquaculture area (Lvhua Island, Shengsi) and six voyages were monitored.
The monitoring results show that the water in the culture area is eutrophic, inorganic nitrogen and active phosphate are the main factors exceeding the standard, and the maximum standard index is 3.21 (calculated according to the second-class seawater quality standard), and the single factors of pH, DO, COD and fecal coliform have not polluted the water in the culture area. In the sediments, the contents of sulfide, organic matter, fecal coliform, total mercury, lead, arsenic and cadmium in the monitored sea area all meet the first-class standards of marine sediment quality; The indexes of total mercury, cadmium, lead, arsenic, copper and petroleum hydrocarbon all meet the first-class standards of marine biological quality; The content of fecal coliform exceeded the standard (≤3/g), with more (1.5 ~ 1.8/g); The contents of DDT, PCBs, paralytic shellfish poisoning and diarrheal shellfish poisoning were not detected.
Dingzuimen aquaculture area
From May to September, 2115, the water quality and sediments in the key seawater aquaculture area in Daishan were sampled and monitored.
The monitoring results show that the average content of inorganic nitrogen in mariculture areas exceeded the national fourth-class seawater quality standards from May to September, and the active phosphate in some waters exceeded the standard, and other monitoring indicators met the mariculture water quality standards. The sediment environment in the culture area is good, and the PCB residue in sediments in some areas is high, which exceeds the national quality standard of the first class marine sediments. The content of cadmium in cultured SINONOVACULA constricta exceeded the standard.
4.2 Environmental conditions of key sewage outlets and their adjacent waters
The sewage outlets of Dinghai Sewage Treatment Plant and their adjacent waters
From April to October, 2115, six cruises were conducted to monitor the sewage outlets and their adjacent waters. The results showed that the indicators of ammonia nitrogen, fecal coliform and biochemical oxygen demand (BOD5) in the sewage outlet waters exceeded the first in the Integrated Wastewater Discharge Standard (GB8978-1996). Chemical oxygen consumption (COD), oil and suspended solids partially exceeded the standard; Volatile phenol, heavy metals, total mercury, cadmium, lead and arsenic meet the standards, and the sewage outlet has certain environmental hazards or potential hazards in the sea area.
The main pollution factors in the waters near the sewage outlet are inorganic nitrogen, phosphate and other nutrients, and the oil also slightly exceeds the standard.
the water area of super-class four seawater in the water body is 28.8km2.
The sewage outlet of Zhejiang Haishengli Group Co., Ltd. and the adjacent sea area
The indexes such as ammonia nitrogen and fecal colon in the sea area near the sewage outlet exceed the maximum allowable discharge concentration (Grade I standard) of Class II pollutants in the Integrated Wastewater Discharge Standard (GB8978-1996); Part of biochemical oxygen demand (BOD5) exceeds the standard; Chemical oxygen consumption (COD), oil, suspended matter, volatile phenol, heavy metal total mercury, cadmium, lead and arsenic meet the standards; The main pollution factors in the water body near the sewage outlet are inorganic nitrogen, phosphate and other nutrients, and the oil also exceeds the standard slightly; In sediments, organic carbon,