RESUMO
Carbon (C), Nitrogen (N) and Phosphorus (P) of water and periphyton were analyzed in the Chaobai River to investigate how anthropogenic river pollution affected the periphyton community and its elemental composition. The results of this study showed that NH4(+) -N and NO(x)(-) -N accounted for 52%, 28% of TN in the Chaobai River, respectively, while 1.6%, 38% of TN in the Baihe River. TP concentration in the former (0.104 mg x L(-1)) was 21 times higher than the latter (0.005 mg x L(-1)). Coefficient of variation (CV) of periphyton C, N and P in the Chaobai River and Baihe River were 0.55, 0.41, 0.62 and 0.24, 0.13, 0.18, respectively. This indicated great variations of periphyton elemental composition in the Bai River than in the Chaobai River. Binary logistic analysis was used to determine factors that affect periphyton distribution. TOC, TN, NO(x)(-) -N, NH4(+) -N, TP, pH, ORP and conductivity were used in this analysis and the result showed that TP was the key factor which can interpret 87.3% of the correct ratio. Periphyton C, N and P had strong correlations and N was the key element of periphyton composition. N: P can track variations of water TN: TP and this periphyton stoichiometric characteristic can be used as indicators of water pollution. TP was the key pollution factor that determined changes of periphyton N: P. This study laid the foundations of investigating variations of the periphyton community and its effect on structure and elemental cycling of higher trophic levels.
