长江干流营养盐通量的初步研究

PRELIMINARY STUDY ON THE CHANGJIANG RIVER MAINSTREAM NUTRIENTS FLUXES

分别于1988年2月（冬季）和1986年6月（夏季）利用比色法对长江干流上游至河口水中营养盐进行测定，根据所测定的营养盐含量和长江径流量计算营养盐通量。结果表明，冬季重庆至河口长江水中NO3－N，NH4-N，TIN，PO4-P和SiO3-Si的平均浓度分别为52.2±66μmol／L，51.8±16.9μmol／L，105.3±11.4μmol／L，0.55±0．06μmol／L和75.2±23.6μmol／L.夏季NO3-N,NH4-N,TIN和SiO3-Si的平均浓度分别为69.0±17.0μmol／L,4.0±1.7μmol／L，73.3±15.6μmol／L和55.8±16.4μmol／L。冬季营养盐通量（除NO2－N外）自上游至下游逐渐增加，它们主要来自中、下游流域。夏季NO3－N，TIN和SiO3－Si通量从上游至下游也有明显的增加趋势，NO3－N和TIN，上游和中、下游几乎各占一半，SiO3-Si主要来自中、下游。夏季NO3－N，TIN，PO4－P和SIO3－Si通量明显高于冬季。

Investigations were conducted in Feb., 1988 and June, 1986 on thenutrients from the upper reaches water of the Changjiang River mainstream to theriver mouth water. Their concentrations were determined by colonmetry and thenutrients fluxes in the Changjiang River water were calculated from concentrations andChangjiang River flow. The average concentrahons of NO3-N, NH4-N, TIN (totainorganic N), PO4-P and SiO3 -Si from Chongqing to the river mouth in winter(February, 1988) were 52.2± 6.6μmol / L, 51.8± 16.9μmol / L, 105.3± 11. 4μmol / L,0.55±0.06μmol / L and 75.2± 23.6μmol / L respectively. Their average concentrationsin summer (June, 1986) were 69.0±17.0μmol / L for NO3-N, 4.0±1.7μmol / L forNH4-N, 73.3±15.6μmol / L for TIN and 55.8±16.4μmol / L for SiO3- Si. Theconcentrations of NO3- N and NH4-N in the Changjiang River water were almost halfof TIN respectively in winter and NO3-N was the main form of inorganic N insummef, and was 93± 4% of TIN. The high atomic ratio of TIN to SiO3-Si (average1.46±0.28 in winter and 1.45± 0.63 in summer) showed that the Changjiang Riverdrainage was seriously affected by human activities. From the upper to lower reaches,the fluxes of the nutrients (except NO2-N) in winter and the fluxes of NO3-N,TINand SiO3-Si in summer gradually increased. The nutrients in winter and SiO3-Si insummer were mainly from the middle and lower reaches. In summer, half of theNO3-N and TIN fluxes came from the upper reaches, the half from the middle tolower reaches. The fluxes of NO3-N,TIN,PO4 -P and SiO3-Si in summer being muchmore than they in winter, was mainly due to increased runoff.Equations of therelationship between nutrients fluxes and the Changjiang River flow are suggested inthis paper.