| Popis: |
Light attenuation has a significant impact on the growth of submersed aquatic vegetation(SAV).SAV occupies a position between the two water and sediment organic nutrition database in aquatic ecosystems,which plays a vital role in the stability of water ecosystems of biological productivity,structure and function.However,with the increasing of water pollution and the accelerated process of eutrophication,there is serious deterioration of water quality worldwide,resulting in light attenuation enhanced widely.The photosynthesis of SAV is the most important metabolic activities.Light is essential for its growth and development.However,the formation of low light is most likely to occur in the water.The growth,development and spatial distribution of SAV are subject to restrict on photosynthesis.SAV receives the amount of light is very limited in water.Light penetrating the water reaches the surface of plant leaves by the constraints of multiple environmental factors.This paper systematically analyzed light attenuation and the associated environmental factors affecting the growth of SAV,and pointed out that light was the most important environmental factor to SAV.Colour dissolved organic matter,chlorophyll,total suspended solids and water itself had direct impact on the intensity decay when light went through the water,which were the most important water quality parameters of light attenuation.Beyond Light factors such as nutrients,sediment,water dynamics and other factors would directly or indirectly affect the light attenuation of water quality parameters,thereby affecting water transparency and turbidity and the photosynthesis of SAV,which were important environmental factors to the light attenuation of SAV.Based on the world-wide recession and large areas disappearance of SAV,enhance the recovery and protection of SAV has become an important issue.There have been done a lot of work on the light attenuation studies of SAV,but still exist some problems.We should strengthen the following areas of research:(1) Enhance the water quality parameters of optical attenuation quantitative expression.There are little studies on the nutrients,sediment and other water quality parameters quantify on the light attenuation,we should strengthen research in this area.(2) Enhance the light attenuation in the diagnosis of combination factors.Each factor which affects the light attenuation is not isolated in the water,one factor always linked with other factors,we should consider the combined effects of multiple factors.(3)Strengthen the delivery of land-sourced pollutants(such as nutrients,suspended particles,etc.) on the impact of SAV.The water quality parameters which affect the light attenuation of SAV mostly from land-based,watershed and estuarine characteristics and anthropogenic pollutants play more role on the growth of SAV light attenuation.We should carry out the research of land-sourced pollutants and provide evidence for the control of the light attenuation factors(such as water quality factor,etc.).(4) Large-scale remote sensing monitoring on SAV.There have been done lots of researches during large-scale,long-term and continuous work on SAV abroad,we should learn from foreign experience,take a wide range of long-term remote monitoring and carry out large-scale research on SAV,in order to promote better recovery and development of SAV. |
