1. East China Sea environmental monitoring center Chen Dong
Analysis on the variation trend of Sea-Water Quality in Southern Yellow Sea and Yangtze River Estuary
East China Sea environmental monitoring center
Chen Dong

2. Contents Introduction
Variation trend of sea-water quality in The Southern Yellow Sea
Variation of sea-water quality at Yangze River Estuary
Variation trend of nutrition in E1 section of South Yellow Sea
Conclusion

3. Introduction
The marine environmental monitoring work in East China sea was undertaken by East China Sea environmental monitoring center since the beginning of 1980s. The monitoring range covers the Southern Yellow Sea and the East China Sea which begins from Haizhou bay (Jiangsu Province) to Dongshan bay (Fujian Province), and the regular monitoring items including sea water, sediment, marine biology, Marine atmosphere etc. Now we have accumulated rich experience and full and accurate materials after more than 20 years monitoring work.
The trend of dissolved oxygen, COD and nutrition in the southern Yellow Sea and Yangtze River Estuary during floodwater period are described, based on the data measured in environmental investigation in the Southern Yellow Sea and Yangtze River Estuary

4. the scope of investigation in the southern Yellow Sea and the Yangtze River Estuary

5. Variation trend of sea-water quality in Southern Yellow Sea
the average content of dissolved oxygen (DO) was about 6.75mg/Land fluctuated from 5.8mg/L to 7.75 mg/L in the Southern Yellow Sea.

6. Variation trend of sea-water quality in Southern Yellow Sea
Chemical oxygen demand (COD) was relative low, fluctuated from 0.4mg/L to 1.2mg/L and the average was 0.8mg/L in Southern Yellow Sea.

7. Variation trend of sea-water quality in Southern Yellow Sea
The content of PO4 was variation. The high value appeared in 1985,1987,1995,1996 and 1997, up to mg/L~0.022mg/L, and the low value appeared in 1988, 1991, 1992 and 2003, it decreased to 0.003mg/L~0.005mg/L.

8. Variation trend of sea-water quality in Southern Yellow Sea
The content of IN in the southern Yellow Sea was variation and a variety period was about a decade, which was keeping in the almost same step with PO4.The value was mg/L in 1985 and descends to 0.130mg/L in 1993, rises again from t1994 and to another tallest value0.462mg/L in 1996 and descends to another lowest value 0.059mg/L in It is worth notice that IN was again rise from 2005.

9. Variation of sea-water quality at Yangtze River Estuary
The condition of instauration oxygen became better. The average content of DO was about 6.5mg/L before 1995 and about 7.0mg/L after that.

10. Variation of sea-water quality at Yangtze River Estuary
The content of COD in Yangtze River Estuary was less than 2.0mg/L and met the first-grade marine water quality standard for years. It was a downward trend before 1996, and went up again after that, descended again in 2004to the levelof1995

11. Variation of sea-water quality at Yangtze River Estuary
The contents of PO4 in the Yangtze River Estuary was keeping on ascension. For 20 years, the content of PO4 had increased 0.02mg/L averagely and the content of PO4 in 2000s was about 3 times compared to it in the end of 1980s.

12. Variation of sea-water quality at Yangtze River Estuary
The contents of IN in the Yangtze River Estuary was keeping on ascension. For 20 years, the content of IN had increased 1.0mg/L averagely and the content of IN in2000s was 4 times compared to it in end of1980s. IN was keeping on a high level in recent years.

13. Variation of sea-water quality at Yangtze River Estuary
Estuary is the interaction of river basin and sea and it is also the destination of material that comes from the river basins. Environment deterioration, caused by more and more human activities and resource exploitation in river basin and estuary, will eventually come out in river estuary. The huge flow of Yangtze River brought abundant nutrient to the estuary and to the coast of East China Sea for years, and nutrient became the major pollution in the sea area and over proof severely. The variation trend of nutrient in Yangtze River estuary shows that the water quality in the Yangtze River Estuary was getting deterioration with the development of economic in the coast of sea and river basin from 1990s. The contents of major pollutions especially nutrient in the Yangtze River estuary are keeping rising, and we should pay much attention to it.

14. sketch map of E1 section

15. Variation trend of nutrition in E1 section of Southern Yellow Sea
The content of PO4 in the E1 section was slowly ascending from 1988 to 2005.

16. Variation trend of nutrition in E1 section of Southern Yellow Sea
The variation trend of IN was complex, it was an ascent trend from 1988 to 1997 and 1998 to present, and the content of IN in1998 was the lowest, after that it rose again.

17. Variation trend of nutrition in E1 section of Southern Yellow Sea
E1 section spans the range of estuary and sea. For inshore sea pollution, estuary is its source and inshore sea area is its influx. The increase of nutrient in Yangtze River estuary will eventually effect on its inshore sea nearby. The content of PO4 in the E1 section water varied as closely as the content of PO4 in the Yangtze River Estuary, which maybe was effected by expanding of Yangtze River water.

18. Conclusion ——the southern Yellow Sea
the water quality in the Southern Yellow Sea (SYS) was variation for 20 years.
the average content of dissolved oxygen (DO) was 6.75mg/Land fluctuated from 5.8mg/L to 7.75 mg/L.
Chemical oxygen demand (COD) was relative low, fluctuated from 0.4mg/L to 1.2mg/L and the average was 0.8mg/L.
phosphate (PO4) and Inorganic nitrogen (IN) were keeping in the almost same step which had a variation cycling of 10 years. PO4 and IN went from high value to low value from and It’s worth to notice that IN was again increasing from 2005.

19. Conclusion ——the Yangtze River Estuary
the water quality in the Yangtze River Estuary was getting deterioration.
The average content of DO was about 6.5mg/L before 1995 and about 7.0mg/L after 1995.
the content of COD was low, all below 2.0mg/L.
The content of nutrition was keeping on ascension . PO4 had increased 0.02mg/L and the content of PO4 in 2000s was 3 times compared to it in 1980s. IN had increased 1.0mg/L and the content of IN in2000s was 4 times compared to it in 1980s.

20. Conclusion ——the E1 section
The water quality in the E1 section effected by water near the shore was getting deterioration.

21. Thanks!