The Study Of Water Environmental Quality And Carrying Capacity Of Luoyuan Bay

Luoyuan Bay, which is located in northeast part of Fujian Province, has become the severe polluted sea area in Fujian Province for successive years and has been serious polluted by inorganic nitrogen and activated phosphate. The eutrophication situation in local environment of Luoyuan Bay has become one of the most severe problems in environmental protection, at the same time, the terrigenous pollutant emission has not been brought under effective control. As a consequence, several red tide events happen in recent years so that economic losses of marine aquaculture has been caused.Through the survey in July, 2009, we make the analysis and evaluation about the environmental quality of both surface water and sea water in Luoyuan Bay area. According to historical data, we also analyze the spatial and temporal variation characteristics of environmental indicators. On that basis, we study the load of pollutants discharged into sea and environmental carrying capacity, moreover, we put forward corresponding environmental management measures, which providing scientific proves for environmental quality and volume control in Luoyuan coastal areas.The results are shown as the follows:1) The results of the survey about the environmental quality of both surface water and sea water have shown that main terrigenous pollutants are permanganate index and the oil, while the main exceeding standard factors of sea water are the reactive phosphate, the oil and inorganic nitrogen. The nutritive levels assessment indicated that the nutrient level of Luoyuan Bay is potential eutrophication, between moderate trophic level and eutrophication level.2) The space distributions of main environmental indexes show that they are effected largely by aquiculture and terrigenous inputs. The interannual changes of nutrients show that the variation tendency of inorganic nitrogen and activated phosphate is almost the same, that is, a rising trend. The change of eutrophication index shows that the nutritive levels of Luoyuan Bay has changed from poor eutrophication in the early 1990s to eutrophication in the early 21st century.3) The load of main pollutants including COD, total nitrogen and total phosphorous are 5456.68 t/a, 1591.03t/a and 212.40t/a respectively. The soil erosion, life pollution and livestock farming constitutes the main terrigenous pollution of Luoyuan Bay.4) Compared with actual total mass into the sea, the row mass of COD, DIN and PO4-P of Luoyuan Bay are no more than the environmental carrying capacity in the condition of the state water quality standard I and marine functional zoning. In these two conditions, the load of TN and TP should be decreased by 177t/a, 83 t/a and 54 t/a, 20 t/a. Meanwhile, considering the environmental conditions and pollution situation, we put forward management measures about the environmental problems, which providing scientific proves for environmental quality and volume control in Luoyuan coastal areas.