SPECTRUM CHARACTERISTICS OF MAJOR IONCONCENTRATIONS AT WUHAN SECTOIN OF THECHANGJIANG RIVER

IINTRODUCTION been used to Interpret waterqualltycharacteristlcs（SHEN，1994）．In fact，the temporal changes of waterSince the 1930s，river water quality has been one quality parameters have ceFtaln re剖larfluctuatlons withof the main topics of water environmental sciences．their own spectrum characteristic and causes．However，Since the 1980s，global change has become the hot spot waterquallty average will lose this statisticall讪matlonOearth science a…

SPECTRUM CHARACTERISTICS OF MAJOR IONCONCENTRATIONS AT WUHAN SECTOIN OF THECHANGJIANG RIVER

ABSTRACT: Spectrum analyses of water quality time series have been carried out for five hydrometric stations including Wuhan hydrometric station of the Changjiang( Yangtze) River, etc. The fluctuations of Ca2 , Mg2 and HCO3-concentrations in river water under different physical geography conditions have about two-year cycle which is corresponding to hydrometeorological quasi-biannual-oscillation(QBO). Na Cl- SO2-4 have about two-year cycle in the area lightly affected by human activities while two-year cycle doesn't exist in the area heavily affected by human activities. All the fluctuations of major ions have about three-month cycle. The river discharge fluctuation accounts for 43. 9% , 45.1%, 54.3%, 33.9%, 30.3% and 42. 7% of the variance of Ca2 , Mg2 HC03-, Na Cl-, SO2-4, respectively, at Wuhan from 1962 to 1985. According to the spectrum characteristic of major ions, the duration of the time series has to be at least 13 years for trend analysis of monthly water quality data.