Analysis and Evaluation on Nutritional Status and Organic Pollution Condition in the Southern Offshore Area of Huangdao District of Qingdao City

Abstract:

The current study analyzed the distributional and variational feature of nutrients of seawater in the southern offshore area of Huangdao District based on the environmental data collected by surveys from 2008 to 2013. The methods of Eutrophication Index (E) and Organic Pollution Comprehensive Index (A) were used to assess nutritional status and organic pollution condition of seawater. Based on the surveys from 2012 to 2013, the concentrations of dissolved inorganic nitrogen(DIN), dissolved inorganic phosphate(DIP) and chemical oxygen demand (COD) varied within 20.82-197.62 µg/L, 4.52- 52.91 µg/L and 0.39-1.25 mg/L, respectively. Except one station that the concentration of DIP was above the standard limit, all other concentration including DIP, DIN and COD met the second class of national standard. In three seasons, the highest concentration of DIN (86.42 µg/L) was in the spring, and the lowest (38.59 µg/L) was in the summer. The highest concentration of DIP (18.68 µg/L) was in the autumn, and the lowest (9.10 µg/L) was in the summer. The highest concentrations of COD (0.962 mg/L) was in the summer, and the lowest (0.682 mg/L) was in the spring. The concentrations of DIN and COD was gradually decreased from 2008 to 2011 and then was increased in 2012. The concentration of DIP was gradually decreased from 2008 to 2010 and then was gradually increased from 2010 to 2012. The seawater of the surveyed area was at oligotrophic level, showing the low possibility of red tide occurrence. The water quality in the surveyed area was good, indicating that seawater was not polluted by organic matters.