潮白河周丛生物群落元素组成与水质变化的生态计量学关系研究

研究了潮白河流域中污染水体对周丛生物群落的碳(C)、氮(N)、磷(P)元素含量以及生态计量组成的影响.结果表明,下游潮白河NH4+-N、NOx--N分别占TN的52%和28%;上游白河则分别占1.6%和38%.潮白河TP含量(0.104 mg.L-1)为白河TP含量(0.005 mg.L-1)的21倍.白河和潮白河周丛生物C、N、P元素的变异系数分别为0.55、0.41、0.62和0.24、0.13、0.18,表明生长于白河周丛生物的元素结构变化更大.无周丛生物的水体NH4+-N和TP的浓度分别为有周丛生物的21倍和11倍.通过对TOC、TN、NOx--N、NH4+-N、TP、pH、氧化还原电位(ORP)和电导率(conductivity)等水质指标进行二元Logistic回归分析得知,水体TP为影响潮白河周丛生物生存的主要因素,其预测正确率为87.3%.周丛生物C、N、P元素间有强相关性,其中N起了"桥梁"作用.生态计量学分析进一步显示周丛生物的N∶P的比值追随水体TN∶TP的变化;并且该比值主要受水体TP浓度影响.周丛生物N∶P可用于水体TN∶TP变化的生态计量学的指示因子.本研究为进一步探究周丛生物群落结构变化,以及对高一级营养级生物群落结构和元素循环的影响奠定了基础.

Ecological Stoichiometric Relationships of Periphyton Community Elemental Composition and Variations of Water Quality in the Chaobai River

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.