长江磷和硅的输送通量

Phosphorus and Silicate Fluxes in the Yangtze River

于1997年枯水期(11月～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、湖泊各种形式的磷和硅酸盐进行了调查。长江干流枯、丰期颗粒磷和总磷浓度变化几乎是同步的,上游快速增加,中、下游下降且变化不大;溶解态磷和硅酸盐浓度变化较小。枯、丰期各种形式磷和硅酸盐通量从上游至中、下游呈增加趋势。枯水期长江各种形式磷和硅酸盐通量,大部分是由中、下游贡献的,其中一半以上来自于支流和湖泊。丰水期各种形式磷和硅酸盐的输送,仅上游支流贡献了一半以上的颗粒磷,其余大部分是由干流贡献的。颗粒磷所占的比例,上游高于中、下游,丰水期高于枯水期,干流高于支流,主要与悬浮泥沙含量有关,颗粒态磷是长江磷的主要贡献者。溶解态磷的输送通量,枯水期干流中有机磷略占优势,支流中有机和无机磷各占一半;丰水期均是无机磷占优势。长江水中各种形式磷和硅酸盐的输送通量和总磷、磷酸盐的输出通量主要受径流量所控制,特别是硅酸盐通量具有比磷更加明显的随径流而增加的特征。本文提出了长江各种形式磷和硅酸盐的输送通量方程式及总磷、磷酸盐的输出通量方程式。

Systematic investigations in various forms of P and SiO3-Si in the Yangtze mainstream and major tributaries and lakes from the Jinshajiang River （a section in the upper Yangtze River） to the mouth were carded out from November to December, 1997 （dry season）, and in August and October, 1998 （flood season）. In the dry and flood seasons in the Yangtze mainstream, the variations in particulate P and total P concentrations were almost synchronous, which increased speedily in the upper reaches and then decreased with less variations in the middle and lower reaches, and the variations in dissolved P and SiO3-Si concentrations were little. The fluxes of various forms of P and SiO3-Si gradually increased from the river＇s upper reaches to the lower reaches. The fluxes of various forms of P and SiO3-Si in the dry season came mainly from the middle and lower reaches and over half of them were contributed by tributaries and lakes. Various forms of P and SiO3-Si in the flood season were mainly contributed by the mainstream except for tributaries in the upper reaches which contributed over half of the particulate P. The ratios of TPP in TP in the mainstream and tributaries were higher in the upper reaches than in the middle and lower, higher in the flood season than in the dry season and higher in the mainstream than in the tributaries, which were clearly relative with suspended matter content. The particulate P was the main contributor of P in the Yangtze River. In transport fluxes of dissolved P, DOP was slightly in dominance in the mainstream in the dry season, while organic P and inorganic P was 50% each in the tributaries. The transport fluxes of various forms of P and SiO3-Si and export fluxes of TP and PO4-P were mainly controlled by runoff, especially, it was more obvious than P that SiO3-Si flux increased with runoff. The transport equations of various forms of P and SiO3-Si and export fluxes equations of TP and PO4-P are suggested in this paper.