Research On The Relationships Between Some Environmental Factors Of The Water Medium And The Concentration Of Total Saccharides Released By Algae

Excessively growth of algae will cause quality worsen for water ecosystem, and leads toenvironmental pollution. Some complex factors will affect the growth of algae. Among them include thechemical compounds secreted by algae. In order to study the feasibility of using saccharide toevaluating the extent of water eutrophication, the relationship between the growth status of alga and theconcentration of saccharide in the water medium, and the relationships among the concentrations oftotal nitrogen, total phosphors and total saccharides have been studied. In addition, impacts of someenvironmental factors on the concentration of saccharide, such as UV-B ray radiation, suspendedparticles and the co-existing of alga, are considered.The contents and the main conclusions of this article are briefly listed below.1. The Phenol-Vitriolic spectrophotometry method was used to measure the concentration of totalsaccharide in micro algae and hydrodictyon reticulatum aqueous solution, respectively. The biomass ofhydodictyon reticulatum was determined by weight. The biomass of micro alga was determined bychlorophyll a and the density of cell in solution, respectively. The relationship between the totalsaccharide secreted by alga and the biomass of alga in its growth process has been discussed. Anequilibrium limit relation between biomass of alga and the concentration of total saccharide wasobserved. During the period of the biomass increase, saccharide act as nutrition supplier. Theconcentration of saccharide decreases with the increase in the biomass of algae. However, if theconcentration of saccharide is too lower to excess the limitation extent, it will limit the growth of alga.The biomass decrease will stimulate more saccharides to be secreted, and the concentration ofsaccharide increases. The relationship between total concentration of saccharide and the biomass of algais shown to be a negative correlation.2. The relationship among the total nitrogen, total phosphors of the medium and the concentrations of total saccharides released by two algae were studied. The hydrodictyon reticulatum was grown inthree batch of culture mediums with different mass ratio of total nitrogen to total phosphor. The microalga was grown in natural water, which simulate environment with lake bed mud as the nutrient source.Experimental result shows that, the total nitrogen and total phorsphor change in an opposite directionagainst the concentration of total saccharide, respectively. Nitrogen and phorsphor are importantnutrient substance for algae growth. The higher concentration of P and N is in favor of algae growth, atthis status, the concentration of total saccharide decreases. The decrease of the total saccharideconcentration may be caused by the monosaccharide consumption, which can readily be taken up byheterotrophs and algae. Severe P-and N-limitation seems lead to a higher production of extracellularpolysaccharide, respectively. This means that the major photosynthetic activity under N-andP-limitation conditions was the synthesis of carbohydrate, the synthesis of lipids and proteins seems tobe suppressed.3. The growth of micro-alga was considered at three radiation conditions, the sunlight radiation, thesunlight plus extra UV-B radiation with strength of 20 and 40 mw/ cm^-2 UV-B, respectively. Thechanges of extra-and intracellular saccharides have been detected. Experimental result shows that, theconcentration of extra cellular saccharide increases with the increase in the UV-B intensity. UV-B rayradiation will damage the algae. Therefore, alga will secrete more saccharides to prevent the radiationinjury.4. The effect of some environmental factors on the growth of hornwort and the concentrationchanges of saccharides is considered. Experimental result shows that, hornwort will secrete more extracellular saccharide if phosphor concentration is less than 0.08 mg/L. The low concentration of phosphoris favor of the accumulation of monosaccharide. Suspended particles stimulate hornwort to excretemore saccharide. The coexistence of micro alga with hornwort decreases the biomass of hornwort, andleads to the increase in the concentration of saccharides.