长江氮的输送通量

1997年枯水期(11～12月)和1998年丰水期(8月和10月),对长江流域从金沙江至河口干流和主要支流、湖泊各种形态的氮(N)进行了调查。各种形态N的基本输送模式为,从上游至河口通量逐渐增加,其中以硝酸盐(NO₃-N)、溶解无机氮(DIN)、总溶解氮(TDN)和总氮(TN)最显著,这与它们的稳定程度有关。长江口各种形式N的输出通量大部分是由中、下游贡献的,特别是枯水期。支流和湖泊贡献的N大约占输出通量的一半以上,其中洞庭湖水系贡献最大,鄱阳湖水系次之。长江枯、丰期三态无机N的输送和输出通量中,NO₃ N占绝大部分。各种形式的溶解N输送和输出通量中,DIN是主要的。在所有形式的N中,溶解形式的N占绝大部分。长江枯、丰期干、支流各种形式N通量和长江口各种形式N的输出通量主要受径流量所控制,与人类活动密切相关。并提出了长江各种形式N的输送方程式。

Nitrogen transport fluxes in the Yangtze River

Systematic investigations in various forms of N in the Yangtze River mainstream and major tributaries and lakes from the Yangtae River in the Yangtze upper reaches to the mouth were carried out from November to December 1997 (dry season),and in August and October 1998 (flood season).There were basic similar models in transport of various forms of N,their transport fluxes gradually increased from the river's upper reaches to the mouth and the most obvious were NO₃N 、 DIN 、 TDN and TN which were consistent with their stability extent.The export fluxes of various forms of N in the Yangtze River mouth came mainly from the middle and lower reaches,particularly in the dry season,and over half of N were contributed by the tributaries and the lakes and the maximum came from the Dongtinghu Lake,then the Poyanghu Lake water systems.In the transport and export fluxes in the dry and flood seasons,NO₃-N was major in three forms of inorganic N,DIN was major in various forms of dissolved N,and dissolved N was major in all forms of N.In the dry and flood seasons,various forms of N fluxes in the Yangtze River mainstream and tributaries and the export fluxes of various forms of N in the Yangtze River mouth were mainly controlled by runoff.The transport equations of various forms of N were suggested by this paper.