滇池水体氮的时空变化与藻类生长的关系

The Spatial and Temporal Variation of Nitrogen and Its Relationships with Algal Growth in Lake Dianchi China

水体氮的时空变化及其与藻类生长的关系对研究水体富营养化具有十分重要的作用。采用GPS定位,对滇池海埂、斗南、罗家村、新街、昆阳5个代表性位点断面水体总氮、铵态氮、硝态氮及叶绿素a含量进行了为期1a的监测和动态研究,全面分析了不同区域、不同层次、不同时期滇池水体各形态氮的时空变化特征及其对藻类生长的影响。结果表明,全湖各采样点水体总氮、铵态氮、硝态氮的平均浓度分别是2.14、0.11、0.20mg·L-1,全年分别在0.66～6.44mg·L-1、0～0.74mg·L-1、0～0.94mg·L-1之间变化。各区域水体总氮的浓度以海埂和斗南最高,铵态氮和硝态氮的变化幅度较大。全湖水体总氮和铵态氮与叶绿素a呈显著正相关,硝态氮与叶绿素a呈负相关趋势;滇池不同区域水体总氮与叶绿素a呈显著正相关,海埂和罗家村位点水体铵态氮与叶绿素a呈显著正相关,海埂位点水体硝态氮与叶绿素a呈显著负相关,其他区域则无显著相关性;水体总氮、铵态氮、硝态氮对藻类生长的影响呈现显著的区域性和水层差异。

Total nitrogen （T-N）, ammonium-nitrogen （ NH4-N ） and nitrate-nitrogen （ NO3-N ） concentrations in the Dianchi water affect algal growth. Studying the spatial and temporal variations of T-N, NH4-N, NO3-N concentrations and their effects on algal growth could help understanding the mechanisms of the eutrophication of Lake Dianchi. Dynamic changes of T-N, NH4-N, NO3-N and chlorophyll a concentrations at different depths of water were determined regularly at five representative sites of Lake Dianchi, namely Haigeng, Dounan, Luojiacun, Xinjie, and Kunyang, respectively, from May 2003 to May 2004. The spatial and temporal dynamic variation characteristic of nitrogen in Lake Di- anchi and their relationships with algal growth were discussed. The results showed that, the concentrations of T-N, NH4-N, and NO3-N in the Lake Dianchi averaged annually at 2.14 mg. L-1, 0.11 mg. L-1, 0.20 mg. L-1, respectively, varied with sites, water depths and seasons. The T-N, NH4-N, and NO3-N concentrations ranged at 0.66-6.44 mg.L-1, 0-0.74 mg.L-1, and 0-0.94 mg.L-1, respectively. Among the five sampling sites, the T-N concentrations in Haigeng and Dounan sites were the highest. The variations in NH4-N and NO3-N concentrations were higher. In the whole Lake Dianchi, T-N, NH4-N concentrations were found positively correlated with chlorophyll a concentrations. However, NO3-N concentrations had negatively correlation with chlorophyll a concentrations. At different sampling sites, T-N concentrations also had significandy positive correlations with chlorophyll a concentrations. However, the positive correlations between NH4-N and chlorophyll a concen- trations were only found in Haigeng and Luojiacun sites. Negative correlation between NO3-N and chlorophyll a was found only in Haigeng. The results indicated that the effects of T-N, NHa-N, NO3-N concentrations on algal growth in Lake Dianchi varied with different sites and different water depths.