环渤海河流营养盐的向海输送及环境效应

Nutrient transport in rivers around the Bohai Sea and its environmental implications

对2017年枯水期、2019年丰水期、2020年丰水期和2021年丰水期环渤海24条主要入海河流溶解态无机营养盐向海输送的浓度、比值和通量进行了分析.结果表明:环渤海河流溶解无机氮(DIN)浓度在世界河流中处于较高水平,硝酸盐(NO_(3)^(-))为DIN的主要赋存形态,溶解硅(DSi)和溶解无机磷(DIP)浓度较低.环渤海河流每年向渤海输送约0.61Gmol氨盐(NH_(4)^(+))、0.24Gmol亚硝酸盐(NO_(2)^(-))、4.85Gmol NO_(3)^(-)、0.02Gmol DIP和3.27Gmol DSi.环渤海小河流在环渤海河流营养盐的向海输送中扮演着重要作用,尤其是DIP的输送可以占入海河流总通量的80%以上;小河流单位流域面积DIN、DIP和DSi输送通量均高于黄河.与世界河流相比,环渤海河流向海输送的营养盐比例失衡,具有高氮磷比、高硅磷比和低硅氮比的特点,磷限制显著.环渤海河流营养盐向海输送和结构失衡可能会进一步影响到渤海的初级生产和生态环境演变,值得深入研究.

The nutrient concentration,flux and structure of 24 major rivers around the Bohai Sea(BS)during the dry season of 2017 and the flood seasons of 2019,2020 and 2021 were analyzed.The results showed that the dissolved inorganic nitrogen(DIN)concentration in rivers around the BS was higher compared with other rivers of the world,and nitrate(NO_(3)^(-))was the principal form of DIN.While concentrations of dissolved silicate(DSi)and dissolved inorganic phosphorus(DIP)around the BS were lower than those in the world rivers.About 0.61 Gmol ammonia(NH_(4)^(+)),0.24 Gmol nitrite(NO_(2)^(-)),4.85 Gmol NO_(3)^(-),0.02 Gmol DIP and 3.27 Gmol DSi,respectively,were transported to the BS annually by these rivers.The small rivers around the BS played an important role in the nutrient delivery,especially the DIP transportation,accounting for more than 80%of the DIP flux of rivers around the BS.And the fluxes of DIN,DIP and DSi in terms of drainage basin area of small rivers were higher than those of the Yellow River.Compared with other rivers of the world,the nutrient composition in rivers around the BS was incongruous with high DIN/DIP(N/P)ratio,high DSi/DIP(Si/P)ratio and low DSi/DIN(Si/N)ratio,and the phosphorus limitation was significant.Imbalance of nutrient delivery from rivers may affect the primary production and environment evolution in the Bohai Sea,which should deserve further attention.