太湖藻源性颗粒物降解过程中营养盐转化及其生态效应

以太湖水体中藻源性颗粒有机物作为切入点,研究了不同环境条件下(有光,无光)藻源性颗粒有机物降解过程中C,N,P等营养元素的形态变化过程,分析了藻源性颗粒有机物对水体营养盐循环和浮游植物生长中的作用.实验结果显示,蓝藻水华过程中,藻源性颗粒有机物最高可占水体总C,N,P比例的81.51%,94.60%,97.47%,是水体营养元素的重要组成部分;有光组颗粒物APA显著高于无光组,说明有光组中颗粒态P降解和转化速率显著高于无光组,但有光组水体中SRP浓度低于无光组,Chl-a浓度高于无光组,说明有光组中藻源性颗粒物降解的同时伴随着藻类的生长,颗粒物释放的SRP被浮游植物吸收并转化为生物量;光照对C,N,P的降解过程有明显影响,无光组颗粒物中C,N,P降解速率是有光组的2倍,可降解比例是有光组的(2.5±0.1)倍;实验中还发现前7d各元素的降解速率要高于之后的降解速率.综上,藻源性颗粒物营养盐总量大,生物可利用性高,降解迅速,且降解产物可被浮游植物吸收,是藻类生长和水华发生重要的营养盐来源.

The transformation of the nutrient in the degradation process of the phytoplankton-derived particulate organic matter and it's ecological effect

The phytoplankton-derived particulate organic matter was taken in Lake Taihu as the breakthrough point.We studied the changing process of the C, N & P elements in the degradation process of the phytoplankton-derived particulate organic matter under the different environmental conditions (light or dark), and analyzed the role of phytoplankton-derived particulate organic matter in the nutrient water cycling and the growth of phytoplankton. During the cyanobacteria blooms, the contents of C, N & P in the phytoplankton-derived particulate organic matter can account for 81.51%, 94.60% and 97.47% of the total content in the water respectively at most, and they were the important parts of the nutrient elements in the water. The APA under the light condition was significantly higher than that in the dark, which showed that the rate of degradation and transformation of P in the particulate organic matter under the light condition is significantly higher than that in the dark. However, the concentration of SRP under the light condition was less than that in the dark and the concentration of Chl-a was higher. The algae grew along with the degradation of the particulate organic matter under the light condition, absorbing the SRP in the water and converted to biomass. The light had a significant impact on the degradation of the C, N & P, for the degradation rates of the C, N & P in the dark were twice that in the light, and the proportion of degradable in the dark was 2.5±0.1 times of that in the light. The degradation of each element during the first seven days was higher than that after the seventh day. In conclusion, the nutrient in phytoplankton-derived particulate organic matter with high yield gross, biological availability, rapid degradation, and degradation products could be assimilated by the phytoplankton, was the important nutrient sources of algae growth.