Abstract:The inorganic nutrients in Laizhou Bay was monitored during 2006~2009. The results showed that due to the runoff of Xiaoqing River, the concentration of inorganic nitrogen in the western Laizhou Bay was significantly higher than that in the eastern area in May and August of 2009. Phosphate and silicate in the western Laizhou Bay were significantly higher than those in the eastern area in May, 2009, and no obvious variation in August. In May of 2009, concentrations of inorganic nitrogen in 53.3% of the seawater exceeded the fourth grade of Sea Water Quality Standard, and all samples exceeded the first grade. In August, concentrations of inorganic nitrogen in 34.9% of the seawater exceeded the first grade. Phosphate was generally at a low level; in May 2009 the seawater sample from the estuary of Xiaoqing River exceeded the third grade, and the other samples met the first grade. Combined data of inorganic nitrogen during 2006~2009 showed a gradually increasing trend in May and a decreasing trend in August. Phosphate did not change obviously in May but apparently declined in August. Silicate did not change significantly either in May or in August. The average ratios of nitrogen to phosphate, silicate to phosphate and silicate to nitrogen were 164, 130, and 0.77 respectively. Inorganic nitrogen pollution was serious, phosphorus was a potential limiting factor in the surveyed area, and this trend is supposed to go further in the future.
