| Summary |
Two streams, one urban and one suburban, in eastern North Carolina were sampled for one year and analyzed for pH, alkalinity, C1-, SO4 2-, Ca 2+, K+, Na+, NH4+, PO4 3-, NO3-+NO2-, particulate P and N, total P and N, TSS @ 105°C, TSS @ 180°C, total volatile solids, and total fixed solids. Piper diagrams were used to characterize baseflow and identified Ca2+, HCO3-, Na+ and C1- as the dominant ions. Piper diagrams also identified samples whose ion concentrations were different than baseflow, and identified additional sources of Ca2+, HCO3-, Na+, C1-, Mg2+ and S04 2- in some samples. A multivariate statistical technique, principal components analysis, helped to group constituents and to suggest mechanisms that controlled the chemistries of the streams. These mechanisms were rainfall, which controlled Na+, C1-, Mg2+ and N03-+NO2-; CaCO3 dissolution, which controlled Ca and HCO3-; fertilizer or biological activity, which controlled PO4 3- and SO4 2-; and an unidentified mechanism that controlled K+. The streams were also compared to historical data and the comparison suggests the streams are more polluted now than similar streams in the past. Most of the constituents analyzed for are not included in the state surface water standards for Class C waters, however those that are included are within the acceptable range. Generally, PO4 3- and NH4+ concentrations were higher and more variable in the urban stream, while NO3-+NO2- concentrations were higher and more variable in the suburban stream, probably because the urban stream has a larger drainage basin and more variable land uses. |
