湖泊沉积物再悬浮对苦草光合机能的影响

Effect of Suspending Lake Sediments on Photosynthetic Function of Vallisneria asiatica

不同光照强度下,研究湖泊表层沉积物再悬浮对苦草光合机能的影响。沉积物再悬浮后大量颗粒细粒径(<4μm)颗粒附着在苦草的叶片上,造成叶片的叶绿素含量降低、叶绿体电子传递速率(ETR)和光合系统I(IPSII)活力(Yield)降低、光能耗散过程变化等不利的影响,并且弱光条件下影响程度较大。文章认为水体沉积物再悬浮对沉水植物的影响主要是细粒径(<4μm)颗粒的作用。太湖沉积物再悬浮后细质颗粒附着在苦草叶片上,影响其光合机能,是苦草种群退化的重要机制之一。

Effect of suspending sediments on photosynthetic function of the submersed macrophyte Vallisneria asiatica was investigated under different light conditions. Main effects on submersed macrophytes by re-suspension of sediments were due to the particles with particle size less than 4μm. The continued suspending sediment particles for 40d in shallow water body resulted in a significant decrease of chla, electron transport rate, harmful change in content of leaf nitrogen and photochemical quenching, and a lower production in V. asiatica both in different light conditions. However, the degree of impact manifested greater in shading light condition than that in natural light condition. Suspending sediment particles made a significantly harmful effect on photo-system 11 activity and photochemical quenching on shading light conditions, but no significantly effect on natural light conditions. It is a possible mechanism for sediment particles re-suspending cooperated with shading light, which induces the degeneration of submersed vegetation.