广西铁山港海草生态区无机N的季节变化规律及其相关性分析

根据铁山港海草生态区2008年1月～2008年11月冬、春、夏、秋4个季节的调查资料,首次探讨了无机态N的季节变化规律及其相关因子的影响。结果表明:研究海区无机态N具有春夏季明显高于秋冬季的特征,其中春、夏、秋季以陆源输入影响为主,冬季以海区自身N的补充影响为主;DIN的组成变化受水温影响较明显,水温较高的春夏季主要以NO3-N为主,分别占DIN的57.91%和73.00%,秋冬季则以NH4-N为主,分别占DIN的78.23%和50.59%。相关分析显示,无机态N与环境因子之间的相关性以夏秋季出现显著性较多,春季次之,冬季最少;形态N之间的相关性,则集中体现在春夏季节NO3-N与NO2-N、NO2-N与NH4-N之间显著以上的正相关影响上,而且三种形态N同时成为DIN含量的控制因子;秋冬季节所有形态N之间均无相关性出现,只有秋季的NH4-N成为DIN含量的主控因子;但所有季节NO3-N与NH4-N之间均无相关性的出现,却从另一个角度说明,浮游植物优先吸收NH4-N并与之构成直接循环已成为海草生态区无机态N循环的最大特点。

Seasonal variation and analysis of inorganic nitrogen in sea-grass ecosystem of Tieshan Bay in Guangxi

Based on the data from the investigation of sea-grass ecosystem in Guangxi Tieshan Bay in four seasons from Jan.2008 to Nov.2008,the inorganic nitrogen transformation rule and its correlation with affected factors were analyzed.The results showed that the contents of inorganic nitrogen were much higher in spring,summer than that in autumn and winter in the sea-grass bed ecosystem.The contents of inorganic nitrogen were mainly affected by terrestrial input in spring,summer and autumn while replenished from the ocean in winter.The variation of DIN composition was obviously influenced by water temperature.The main existing states of nitrogen was NO3-N in spring(account for 57.91%),summer(account for 73.0%) whereas NH4-N in autumn(account for 78.23%) and winter(account for 50.59%).The correlation analysis showed that the inorganic nitrogen were most likely to have a correlation with the environmental factors in summer and autumn,less in spring and least in winter.In spring and summer there were significant(p≤0.05) positive correlation between NO3-N and NO2-N,NO2-N and NH4-N,these three states of nitrogen were all controlling elements of DIN.There were no correlation appears in autumn and winter,NH4-N becomes the controlling elements of DIN in autumn.The phytoplankton were tend to directly absorb NH4-N because of there were never correlation between NO3-N and NH4-N appears in all seasons,it was the biggest characteristic of DIN cycle in sea-grass ecosystem of Guangxi Tieshan Bay.