南太湖入湖口叶绿素a时空变化及其与环境因子的关系

Spatial-temporal Characteristics of Chlorophyll-a Concentration and Its Relationship with Environmental Factors in the Inlets of South Taihu Lake

根据2010年1-12月专项监测数据,分析南太湖入湖口水域叶绿素a含量的时空变化特征以及与水温和营养盐等主要环境因子的相关性。研究表明,叶绿素a含量随时间变化明显,夏季最高,秋冬季次之,春季最低;在空间分布上,太湖西南入湖口水域的叶绿素a含量明显高于太湖南部入湖口水域。叶绿素a含量全年平均值为(15.71±11.24)μg/L,变化范围在1.50～74.3μg/L。叶绿素a含量与水温、pH、高锰酸盐指数(CODMn)、总磷(TP)、氨氮(NH4+-N)呈极显著正相关,与溶解氧(DO)、总氮(TN)、TN/TP呈极显著负相关。叶绿素a含量变化受多个因子共同影响,水温是叶绿素a含量变化的关键因子。氮磷比平均值为17.8,在藻类生长氮磷比的最佳范围内,易发生蓝藻水华。叶绿素a含量的对数与TP的对数呈极显著正相关,与TN和TN/TP的对数呈极显著负相关。磷是南太湖入湖口水域浮游植物生长的限制因子。

According to the monitoring data in the inlets of South Taihu Lake from January to December 2010, the spatial-temporal characteristics of chlorophyll-a concentration and the correlation analysis between the chlorophyll-a concentration and main environmental factors including water temperature and nutrients were investigated. The re- sults indicated that there was an obvious temporal and spatial variation of chlorophyll-a concentration. The highest average concentration of chlorophyll-a was monitored at summer, the lowest was monitored at spring; the average ehlorophyll-a concentration at southwest of Taihu Lake was higher than that at south of Taihu Lake. The annual av- erage of chlorophyll-a concentration was （15.71 ± 11.24） μg/L, ranged from 1.50 μg/L to 74.3 μg/L. Signifi- cantly positive correlations were found between chlorophyll-a concentration and water temperature, pH, permanga- nate index （CODMn）, total phosphorus （TP）, and ammonia-nitrogen （NH4＋-N）. Significantly negative correla- tions were found between chlorophyll-a concentration and dissolved oxygen （DO）, total nitrogen （TN）, and TN/ TP. The chlorophyll-a concentration was influenced by multi environmental factors, and the water temperature was the key factor. The average value of TN/TP was 17.8, which was in the best range for the growth of algae and made the cyanobacterial bloom happen easily. Significantly positive logarithmic correlation was found between chlo- rophyll-a concentration and TP. Significantly negative logarithmic correlations were found between chlorophyll-a concentration and TN, TN/TP. Phosphorus was the main limited factor for the growth of phytoplankton in inlets of South Taihu Lake.