中文摘要：

为查明秦皇岛近海大面积褐潮连年暴发的成因,在2013年3—11月对该地区主要入海河流和沿岸褐潮暴发区的生源要素污染进行了连续调查研究。调查结果表明,所调查入海河流普遍为劣V类地表水,总氮（TN）超标严重,按照氮污染程度由高到低排列依次为大蒲河〉洋河〉戴河〉石河〉汤河〉东沙河。各河流中的碳、氮、磷、硅等污染物浓度在时间变化上没有统一规律。基于综合污染指数法的评价结果显示,大蒲河和洋河为重度污染,戴河和汤河从先前的轻度污染加重为中度污染。从污染物入海量上看,TN和化学需氧量（COD）是排放量最高的两种河源污染物,其中溶解态氮占TN的74.6%。在所调查河流中,洋河和大蒲河分别贡献了TN的38.2%和33.2%,同时大蒲河还贡献了75.8%的活性磷酸盐和37.7%的活性硅酸盐,而75.9%的COD来自汤河、洋河和大蒲河。秦皇岛河源污染物排放在时间上较为集中在6—9月的丰水期,但各河流单独的排放具有随机性,没有统一的季节性规律,表现出受人为调控影响明显的特点。秦皇岛沿岸褐潮暴发区的生源要素变化与河源污染物排放有显著性相关（P=0.05）。

英文摘要：

We carried out successive surveys from March to November in 2013 to decipher the mechanism of local large-scale brown-algae tide that broke out annually recently along coastal sea off Qinhuangdao, Hebei, China. The surveys show that water quality in all the tributaries was worse than Grade V according to China＇s national standard GB3838-2002 as the total nitrogen（TN） was excessively high. Among all tributaries, Dapu River showed the highest TN level, followed by Yanghe River, Daihe River, Shihe River, Tanghe River, and Dongsha River. No consistent temporal patterns of variations in the concentrations of N, P, Si and C in the tributaries were observed. The comprehensive pollution index reveals that pollution in Dapu and Yanghe Rivers was ＂serious＂ according to the national standard, and in Daihe and the Tanghe Rivers was ＂intermediate＂ but aggravated recently. In addition, TN and COD were two primary pollutants in these rivers; 74.6% of TN was in dissolved nitrogen. Yanghe and Dapu Rivers contributed 38.2% and 33.2% of TN, respectively. Dapuhe River contributed 75.8% of PO_4-P and 37.7% of SiO_3-Si. 75.9% of COD was from Tanghe, Yanghe, and Dapu Rivers. Most of pollutants from tributary rivers were discharged in high-flow season from June to September. Although discharge from single rivers was random in time and space, influence of human activities was obvious. Overall, correlation between river pollution level and concentrations of bioactive elements was significant（P=0.05）, thus it is clear that land-sourced pollution should be reasonable for the brown tide incidents in recent years.