Load estimation and assessment of land-based pollution for Quanzhou Bay and their relevance to the Total Quantity Control of Pollutants Discharged into the Sea (TQCPS) Program in China

Abstract

The Total Quantity Control of Pollutants Discharged into the Sea (TQCPS) Program belonged to the Public Science and Technology Research Funds Projects of Ocean in China, launched in 2008. As one of the most important and typical demonstration cases of the TQCPS Program, a full investigation of the land-based pollutions discharges around Quanzhou Bay, China developed the total input for three main environmental factors (NH3–N, TP, COD) which were estimated and quantified in 2008 and 2012, respectively. Combined with the trend of seawater quality changes in Quanzhou Bay in the same periods, the effects of the program's implementation were then evaluated. On the whole, by using the basic survey data and export coefficient method, the total amounts of NH3–N, TP and COD discharged into the bay were estimated to be approximately 888.3, 130.6 and 14527.4 t/a in 2008, and 1518.6, 558.8 and 19986.7 t/a in 2012, respectively, where the percentage of the discharge from domestic sources (46.5% in 2008 and 45.2% in 2012) was generally higher than that from the other sources. Based on the characteristic of geography and administrative division, the land areas around the bay were divided into three parts: the south coast region (SCR), the west coast region (WCR), and the north coast region (NCR). The SCR and WCR accounted for 59.2 and 35.4% of the COD loads, and 49.2 and 48.0% of NH3–N loads in 2008. The NCR contributed less of the industrial pollution, but most to domestic pollution (54.1%), followed by 26.2% in the SCR in 2012. The contributions of the discharge from different land areas to the pollution of Quanzhou Bay were found to be differed in 2008 and 2012. Due to the difference in the levels of the economic development among these three areas, the discharge of pollutants from the north coast was much lower than that from the other two parts in 2008; however, following our suggestion of the moderation and optimization of the industrial distribution and the sewage discharge around Quanzhou Bay, the contribution of the west coast decreased while that of the north coast increased significantly in 2012. Furthermore, to a great extent, because of some marine ecological rehabilitation projects, which were also suggested by our TQCPS Program and finally adopted by local government and then developed recently in Quanzhou Bay, the seawater qualities there were improved by in 2012. A longer time and greater efforts are needed to reduce the discharge of land-based pollutants and to improve the marine ecological health and sustainability further. Based on the demonstration results of the research and practice of the TQCPS Program in Quanzhou Bay, some recommendations were suggested. These require further implementation and management and can be transferred to similar estuaries and bays in southeastern coastal areas of China.