Study On Community Structure Of Benthic Diatoms And Its Relationship With The Environmental Factors In Nanming River

The ecosystem of river is the important pathway in cycle of matter. It has the functions of adjusting climate, improving ecological environment and protecting biological diversity. The river is an important part of ecosystem in the city. Nanming River, the branch of Wujiang, is the biggest river in Gui Yang. The systematic investigations of the relationship between benthic diatoms and environment in Nanming River have not been reported yet. Benthic diatoms were collected and identified. At the same time, the writer analyzed the relationship between the species, number, distribution of benthic diatoms and the factors of environment in Nanming River. At last the water quality in Nanming River was estimated. The results demonstrated that there are 114 species of benthic diatoms.They consist of 2 classes 6 orders 10 families 22 genera. Most of them belong to Pennatae, accounted for 93%. Navicula is the most in Naviculaceae of Biraphidinales, amounted to 24 species; Gomphonema is less in Gomphonemacene, amounted to 16 species; Nitzschia is the least in Nitschiaceae of Aulonorapidinales, amounted to 14 species. The species of Centricae are rarely. And the species mainly belong to Coscinodiscaceae . The number of benthic diatoms is 6.356×10³-10.596×10³ in every square centimeter.The content of Ca²⁺ in the cations and [HCO₃^-+CO₃^2-] in the anions are the highest in Nanming River. There are positive significant correlations between conductivity and the content of K(+r = 0.644,P<0.05). There is no clear relationship between conductivity and the rest ions. There are significant positive correlations between the number of benthic diatoms and the contents of Ca²⁺(r = 0.633,P<0.05).There are positive significant correlations between the number of benthic diatoms and TN/TP(r = 0.910,P<0.01), TN and COD(r = 0.811,P<0.01), TP and COD( r = 0.679,P<0.05), TP and TN(r = 0.857,P<0.01). There are negative significant correlations between TP and DO(r = -0.917,P<0.01),TN and DO(r = -0.680,P<0.05), pH and TN/TP(r = -0.692,P<0.05).The water quality is estimated by the construction of the benthic diatoms and the index of DAIPO, BI, Shannon-Weaver and Lloyd-Ghelardi. The overall assessment is that the first sampling points belong to oligosaprobic - mesosaprobic zone , the number two and four is oligosaprobic zone, the number ten and eleven is polysaprobic zone. The rest are mesosaprobic zone.