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于2008年4月至2011年4月对九龙江河口的营养盐进行了8个航次的调查,包含丰水期(5～9月)和枯水期(10月～次年4月).结果表明,九龙江口上游营养盐浓度很高(硝酸盐NO3-N120～230μmol/L,亚硝酸盐NO2-N5～15μmol/L,氨氮NH4-N15～170μmol/L,磷酸盐SRP1.2～3.5μmol/L,硅酸盐DSi200～340μmol/L),且枯水期高于丰水期.NO3-N是溶解态无机氮(DIN)的主要组分,枯水期NO3-N可占DIN的55%～72%,而丰水期该比例则高达67%～96%.NO3-N和DSi在盐度1～32的河口混合区基本呈现保守混合行为.SRP在盐度1～25的区域浓度变化很小(1.0～2.0μmol/L),在盐度>25的区域则被相对低营养盐的近海海水所稀释.利用高分辨率的径流量资料和淡水端实测营养盐浓度,计算出九龙江DIN,SRP和DSi的入河口通量分别为34.3×103tN/a,0.63×103tP/a和72.7×103tSi/a;而通过将营养盐在高盐段的保守混合规律外推至零盐度估算河口输出有效浓度的方法,估算出九龙江口营养盐的入海通量分别为34.8×103tN/a,0.82×103tP/a,71.6×103tSi/a.利用LOICZ推荐的营养盐收支模式方法,估算调查期间九龙江口对SRP的添加量为0.16×103tP/a.与世界其他河流对比,九龙江流域单位面积上的NO3-N产率处于较高水平.与历史数据相比,近10余年来九龙江口上、中游NO3-N和SRP的浓度增加2～3倍,而DSi浓度在九龙江口盐度梯度上的分布则改变不大.这种营养盐年代际变化与密西西比河DIN和SRP升高而DSi浓度大幅度下降的变化特征很不相同.
From April 2008 to April 2011, eight voyages of nutrients in the estuary of Jiulong River were surveyed, including wet season (May-September) and dry season (October-April) (NO3-N120 ~ 230μmol / L, nitrite NO2-N5 ~ 15μmol / L, ammonia nitrogen NH4-N15 ~ 170μmol / L, phosphate SRP1.2 ~ 3.5μmol / L , Silicate DSi200 ~ 340μmol / L), and dry season is higher than wet season.NO3-N is the main component of dissolved inorganic nitrogen (DIN), dry season NO3-N can account for 55% to 72% DIN, and In the wet season, the proportion was as high as 67% -96% .No3-N and DSi showed conservative mixed behavior in the estuarine mixed area with salinities of 1 to 32. The concentrations of SRP varied from 1 to 25 in the salinity range (1.0 ~ 2.0 μmol / L), and was diluted by relatively low nutrient seawater in salinity> 25. By using high-resolution runoff data and measured freshwater nutrient concentration, The estuary flux of DSi was 34.3 × 103tN / a, 0.63 × 103tP / a and 72.7 × 103tSi / a, respectively. However, the effective output of estuary was estimated by extrapolating the conservative mixing law of nutrients in high salinity to zero salinity The method, estimated The nutrient flux into Jiulong River Estuary was 34.8 × 103tN / a, 0.82 × 103tP / a and 71.6 × 103tSi / a, respectively. Using the LOICZ recommended method of nutrient budget, the estimation of SRP addition in Jiulongjiang Estuary was 0.16 × 103tP / a. Compared with other rivers in the world, the NO3-N yield per unit area of Jiulong River Basin is at a relatively high level. Compared with the historical data, NO3-N and SRP While the concentration of DSi did not change much in the salinity gradient of Jiulongjiang Estuary.The change of interdecadal variation of nutrients and the increase of DIN and SRP of Mississippi River and the sharp decrease of DSi concentration Are not the same.