Abstract: The changes in chemical factors and their correlation in spring and summer were analyzed by statistical method，and pollution evaluation was conducted in coastal waters in north Hangzhou Bay based on the investigation data including pH， salinity， temperature， and levels of dissolved oxygen， chemical oxygen demand， nitrate nitrogen， nitrite nitrogen， ammonia nitrogen， and reactive phosphate in north Hangzhou Bay from 2011 to 2015 in order to know the water quality and potential eutrophication and pollution in coastal waters in north Hangzhou Bay.The results showed that the average pH was 8.05±0.11 in spring and 7.96±0.27 in summer and that the average concentration of dissolved oxygen was(8.13±0.33)mg/L in spring and(7.42±0.31)mg/L in summer， with dissolved oxygen saturation of over 88%.Salinity was primarily affected by tides，runoff and rainfall and showed a large fluctuation range， with average salinity of 11.67±5.60 in spring and 12.06±3.28 in summer.The average concentration of CODMn(less than 3 mg/L)was consistent with the second group of criteria according to sea water quality standard，and the concentrations of total ammino nitrogenl(TAN)and －N were kept at a low level， meeting requirement for fish and shrimp and water quality standard for fisheries.During the whole survey，the descending order of three forms of nitrogen levels was expressed as－N＞TAN＞－N， －N accounting for 69%－97%in DIN.There was a negative correlation between pH value and levels of nutrients nitrogen and phosphorus，with positive correlation between nitrogen level and phosphorus level.The potential eutrophication analysis revealed that the eutrophication levels of the studied area were reduced from levelⅥP(spring from 2011 to 2014)to level VP(from summer of 2014 to 2015)， indicating that the P－limited eutrophication level was gradually weakened.According to the first class seawater quality standard，organic pollution index in the coastal waters in north Hangzhou Bay was over 4 during the survey period， indicating that the water quality has been seriously polluted， and that effective control and scientific management should be the ways and means to improve the water quality in the coastal waters in north Hangzhou Bay.
张丹, 孙振中, 张玉平. 春、夏季杭州湾北部近岸水域水化学及营养状况评价[J]. 大连海洋大学学报, 2017, 32(6): 724-722.
ZHANG Dan, SUN Zhen－zhong, ZHANG Yu－ping. Changes in chemical factors and pollution evaluation in coastal waters in north Hangzhou Bay in spring and summer. Journal of Dalian Ocean University, 2017, 32(6): 724-722.
2017, Vol. 32 
