[Diurnal variation and evaluation of water quality of Panxi River in spring].

ABSTRACT

Based on the investigation of water quality of Panxi River in spring, 2010, we assessed the diurnal variation of water quality in spring and the characteristics of water quality changes within a day by using non-parametric test, analysis of variance and grey relationship analysis. The results showed that the differences were not significant for t, DO, COD, Pb, Cd, Zn and Cu (P > 0.05) in upstream, midstream and downstream, but significant difference existed among the pH, EC, TP, TSS, BOD5, NO3(-) -N, TN and NH4(+) -N contents. The diurnal variation of different water quality parameters presented distinct patterns TN, TP and EC increased wavelike with time in upstream, fluctuated less in middle and showed the "single-peak single-valley" pattern in downstream, with the peak at 1200. The diurnal variation of COD showed that "single-peak" pattern and with the peak at 1000 in upstream and midstream and peak at 1200 in downstream. The concentrations of Pb, Cd, Zn and Cu were low and peak at 1200 in midstream; The grey relationship analysis indicated that the water quality in upstream was inferior to the V class of surface water at 1800 and 2000 and were in the II class of surface water for the rest hours, and the water quality in midstream was inferior to the V class of surface water at 1200 and were in the II class of surface water for the rest hours; and the water quality in downstream was inferior to the V class of surface water all time during investigation.