The relationships between environment and economy of Qingdao City by using water quality parameters in Jiaozhou Bay

The relationships between water quality parameters in Jiaozhou Bay and GDP per capita in Qingdao city were analyzed based on the data from 1980 to 2010. It was indicated that DIN concentration in Jiaozhou Bay had a linear increase trend with time in the last 30 years, however, the fitting relationship with GDP per capita of Qingdao city shown a typical EKC curves with its pick at a GDP per capita of~45000/a. A N-type curve was shown between concentration of PO4-P/COD in Jiaozhou Bay and GDP per capita in Qingdao city with the turning point at GDP per capita about 52000~57000 RMB/a. PO4-P concentration in Jiaozhou Bay was fluctuating over time. It was affected by phytoplankton and their ecological responses to nutrient structure of the seawater due to its shortage comparing with DIN. COD concentration varied along with the economic index and had a previous trend of derease in the last few years. This trend reflected the influence of investment for environmental protection but more impacted by the control of point sources. Both PO4-P and COD were not entirely controlled by pollution govern-related economic activities. Control of waste water discharge by environmental protection measures and industrial structure adjustment to reduce emission of pollutants are always the direct reason to improve the relationships between environment and economic, however sufficient investment for environmental protection regulates this improving processes. This study may provide a reference for understanding the relationships of environment and economic to other coastal cities in China.