An Environmental Friendly Approach Of Removing Algae And Mechanism Research About Preventing Carbon Release

The problems of harmful algae blooms have attracted worldwide attentions.The bloom of harmful algae would cover water surface and block sunshine,as a result,intensity of photosynthesis would decrease and concentration of oxygen drops leading to high mortality of animals.Currently a lot of effective methods have been proposed to remove HABs,but little can avoid having negative influence on environment,especially when it comes to releasing greenhouse gases.Now a method combining physical,chemical and biological approach of removing algae was proposed.Flocculants were added to remove the algae down to sediment,then capping materials were laid above the sediment and finally submerged macrophytes were planted in,in order to remove algae,prevent re-suspension and reverse vicious circle.The essay analyzed density of algae,dissolved oxygen,greenhouse gases releasing and microorganism community and there are the main results:(1)The combination of flocculation,capping and submerged macrophytes of removing algae units the merits of physical,chemical and biological method,which is simple,economic and highly efficient.This combination can achieve 99%±1% of algal removal rate,and prevent algae suspend again so the high algal removal rate can be sustained.(2)This combination method can remove the algae covering the surface,as a result,the sunlight can penetrate and the leaves of macrophyte can produce oxygen through photosynthesis.Although it would be hard for dissolved oxygen pass through sediment,macrophytes can provide oxygen to the roots through hollow tissue and the condition of dissolved oxygen in the sediment could be improved as a consequence.(3)The change of dissolved oxygen leads to the change of microorganism community.Under the effects of submerged macrophyte,Arenimonas,Actibacter and Thermomonas that are active in aerobic metabolism became the domain genus and replaced Clostridium,Romboutsia and Sporacetigenium that are beneficial for the generation of methane.(4)This combination method can reduce greenhouse gases releasing from water system.It can prevent 60% methane and 53% carbon dioxide from releasing.That means it can reduce release from water system,an important carbon source in nature.(5)Methane is the final product of anaerobic metabolism,and it was mainly produced in sediment.Submerged macrophytes can reduce methane production through 1)changing microorganism community in the sediment;2)providing more oxygen so methane is more likely to be oxidized;3)absorbing organic matter that can be degrade into methane,cutting the release from generation source;(6)Submerged macrophyte also can reduce the release of carbon dioxide through 1)absorbing organic matter and 2)absorbing carbon dioxide through photosynthesis;(7)Water system with HABs can release a great amount of carbon greenhouse gases becoming a carbon source that cannot be neglected.Carbon in water system would be lose into atmosphere as greenhouse gases.While with the help of submerged macrophyte,not only the concentration of dissolved oxygen would rise and the release of greenhouse gases would drop,but the total carbon mass could increase because of carbon fixation.This method can lay a fundamental basis for future research about carbon sink.This paper not only proposed a simple,high-proficient and environmental friendly approach to remove algae,but also explore the way carbon flows through research on carbon migration,transformation and release,which provide a theoretical and imperative basis for future research about carbon.