苦草光合作用日变化对水体环境因子及磷质量浓度的影响

在静态实验系统中通过水下饱和脉冲荧光仪（Diving-PAM）和多参数水质监测仪（YSI）监测沉水植物苦草（Vallisneria natans）叶绿素荧光参数与水质物理指标的日变化,并同时跟踪测定水体中各形态磷的质量浓度,以研究苦草光合作用日变化对水体物理因子和磷质量浓度的影响。结果表明,苦草叶片光合作用的相对电子传递速率（rETR）,非光化学淬灭系数（qN）及快速光响应曲线的变化趋势和叶片表明的光照强度日变化同步,呈单峰曲线变化;光系统Ⅱ（PSⅡ）实际量子产量（Yield）和光化学淬灭系数（qP）与叶片表明的光照强度日变化相反,呈单槽型曲线变化。水体中溶解氧（DO）、pH和氧化还原电位（Eh）的日变化趋势和与苦草光合作用趋势一致,也呈单峰曲线,均在12：00—13：00时达到最高值。水体总磷（TP）与溶解性总磷（DTP）质量浓度在14：00达到最低值（TP 0.015 mg.L-1,DTP 0.010 mg.L-1）,在24：00达到最大值（TP 0.031 mg.L-1,DTP 0.025 mg.L-1）,溶解性活性磷（SRP）质量浓度在6：00—18：00保持在较低的水平,且无明显波动（0.38~2.46μg.L-1）,在24：00达到最大值（9.62μg.L-1）。水体各形态磷的质量浓度变化呈白天降低、夜间升高趋势,水体中各形态磷的质量浓度变化与苦草光合作用日变化趋势相反。实验结果表明,苦草光合作用引起的水体中环境因子的日变化影响了沉积物磷释放的动态平衡过程,从而引起水体磷质量浓度的日变化。

Effects of diurnal change of V natans photosynthesis on environmental factors and phosphorus concentration in water

In order to study the effects of V.natans photosynthesis on environmental factors and phosphorus concentration in overlying water,the chlorophyll fluorescence parameters and environmental factors were investigated using Diving-DAM and YSI in a static simulative experiment,phosphorus concentrations were also analyzed.The results indicated that the relative electron transport rate（rETR）,non-photochemical quenching（qN） and rapid photo response curves changed synchronously with the photosynthetic active radiation on the leaves as a single-peak curve.The practical yield（Yield） of photosystemⅡ（PSⅡ） and photochemical quenching（qP）changed contrarily with the photosynthetic active radiation as a single-trough curve.The dissolved oxygen（DO）,pH and redox potential（Eh） changed synchronously with photosynthesis of V.natans as a single-peak curve,reached the maximal value at 12：00-13：00.The concentrations of total phosphorus（TP） and dissoluble total phosphorus（DTP） reached the minimal value at 14：00（0.015 mg·L-1,0.010 mg·L-1）and reached the maximal value at 24：00（0.031 mg·L-1,0.025 mg·L-1）.Soluble reactive phosphorus（SRP） concentration maintained in a low level from 6：00 to 18：00,without fluctuation（0.38-2.46 μg·L-1）,and reached the maximal value 9.62 μg·L-1 at 24：00.The concentrations of different phosphorus changed contrarily with photosynthesis of V.natans,decreased in the day and increased at night.The results indicated that the balance of phosphorus between sediment and water was affected by diurnal changes of environmental factors which coursed by photosynthesis of V.natans.The changed balance of phosphorus between sediment and water affected the diurnal changes of phosphorus concentration.