| After running the Three Gorges Reservoir, the water phase flow rate is slow, the factors affecting the growth of algae, such as nutrient concentrations, temperature, carbon content, flow velocity etc undergone certain changes to the massive growth of algae provides one of the important conditions. It has been shown many times in recent years, the Jialing River backwater area to monitor the occurrence of algal blooms, and therefore it is necessary for the Jialing River backwater area of water and nutrients environmental indicators studied. Algae blooms and excess nitrogen, phosphorus and other mineral nutrients of course closely related to, but not the only reason. Many reports confirm that in nitrogen, phosphorus content lower basin still have algae bloom, and carbon as a major factor in the growth of algae, which in the form of changes in characteristics of natural water and its effects on algal growth also becomes particularly important.In this paper, a tributary of the Jialing River Three Gorges Reservoir for the study, for a period of one year term observation study（2011.11- 2012.11） for its backwater areas. Obtained the following four aspects main conclusions:①variation of the basic water quality indicatorsTemperature, flow rate, p H, DO, N, P and so on all affect the growth of algae, so detecting its change law becomes especially important: each observation point temperature is the lowest temperature in February, the highest water temperature in summer. In the middle of march to May 20 ℃ temperature keep the most easily in algae breeding. Two rivers and the sea in the Yangtze river section of nearshore velocity was clearly each observation point of jialing river shore velocity, algal blooms probability on the low side, the jialing river section of the nearshore velocity at various points in the rain water than usual in the spring（march） and flood season, the height of the water phase velocity. Affected by temperature, algae growth, velocity integrated five spots to DO both as the sudden rise in late January and march began to decline, in late September DO inched back with temperature drop. Yangtze river section of the p H slightly higher than the period of observation point of p H value of jialing river, almost the same change rule in each observation point, both fell during the winter, the end of February with the increase of algal density rise abruptly, throughout the spring and summer to keep high p H value, p H in September with the temperature sharply declined. Velocity faster two rivers and the sea at various points in the algal density was far below the jialing river Yangtze river section. 2 month in chongqing section of jialing river water sensitive eutrophication of water bodies, the total density of algae in rapid growth, from march to peak began to decline, entered the flood season in June, after rains velocity faster in jialing river Duan Zao density low, contaminated serious magnetic device mouth, dragon bridge observation point total algal density is significantly higher than other sample points, followed by velocity slower Chao Tian Men observation point. March and April, observation point monitoring found that sudden high content of TP and slight fluctuations, the reasons may be the river by boat blowdown, down with pollution, comprehensive influence of farm fertilization, march and April, each observation point and two rivers and the sea of jialing river, the change rule of the Yangtze river section is altogether of total phosphorus content significantly greater than in other time period, indicating that the jialing river section of phosphorus pollution is mainly for non-point source pollution. Jialing river each observation point and two rivers and the sea of the Yangtze river（altogether） in June to September and February 10 water, may（level period） TN concentration difference is not big, can be concluded that in addition to the influence of abnormal rainfall 3 4 month volatile, each observation point of nitrogen nutrient level of non-point source pollution and point source pollution.② carbon chemical speciation of elements characteristic variationLook from morphological distribution: inorganic carbon in the sample point TC（TIC） accounts for the main proportion, average accounts for 88% of the TC, and organic carbon（TOC） is notably smaller, on average 12% of TC, the content of particulate organic carbon（POC） almost can be ignored, accounting for 2% of the TC. Look from along the: Da Xi Gou, magnetic device mouth Chao Tian Men, dragon bridge TC content declined slightly, this may be in addition to the food and beverage wastewater, magnetic device mouth, dragon bridge also affected by sewage. The two rivers and the sea Yangtze river section in addition to the content of less granular inorganic carbon were significantly lower than other sampling points. From the formation distribution of magnetic device mouth, dragon bridge, Da Xi Gou, Chao Tian Men TC, TIC, PIC, all show the same POC content > level period > mutagenicity, TC, TIC, PIC, POC is mainly affected by non-point source pollution. DIC due to the effect of algae to absorb, in addition to the early march in a similar performance to the plentiful > the mutagenicity of non-point source pollution. The TOC in addition to the abnormal changes of rainfall and faster in March and April, the overall performance for the plentiful > the mutagenicity of non-point source pollution. DOC content altogether less than water, that DOC is mainly affected by the point source pollution. And rapid velocity of algal density low carbon Yangtze river section of the form are shown as the plentiful than water, that its main affected by non-point source pollution.③Carbonic anhydrase activity researchFrom the time distribution of carbonic anhydrase, magnetic device mouth, dragon bridge, Da Xi Gou, Chao Tian Men there was no significant difference, the fastest velocity of two rivers and the sea in the Yangtze river section of the carbonic anhydrase activity are much smaller than the other four sampling points, from the time distribution of carbonic anhydrase: magnetic device mouth, dragon bridge, Da Xi Gou, Chao Tian Men, the distributions of the two season five sampling sites in Yangtze river section of algal blooms of carbonic anhydrase activity trends there was no significant difference, are entering the algae growing in March, the carbonic anhydrase activity in water rapidly increased, peak in the middle of march. After entering April, five samples of carbonic anhydrase activity began to slow down. From the carbonic anhydrase activity and water based index analysis: jialing river backwater reach optimum temperature of carbonic anhydrase activity for 13 ℃; Enzyme activity increases with the increase of p H; By the dual effects of HCO3- and the solubility of CO2, DIC is inversely proportional to the carbonic anhydrase enzyme activity; Algal density is proportional to the carbonic anhydrase enzyme activity; TN, TP, the impact on the enzyme activity was not significant.④Correlation analysisFrom the bivariate correlation analysis available: inorganic and organic carbon can transform each other, but had no obvious influence each other. The TOC affected by the carbon particles is bigger. DTC is mainly affected by the solubility inorganic carbon source. TC, TIC and TOC is mainly by the effects of river scouring. Algal cells to absorb carbon source is DTC, mainly through photosynthesis into organic carbon and oxygen, and high temperature for algae growth. Affect the jialing river bloom season carbonic anhydrase activity of the main influence factors for the POC, DTC, DIC, algal density, p H. From the partial correlation analysis available: algal density and PTC, POC as a significant positive correlation, and DTC, DIC as a significant negative correlation, correlation between DOC and constant, and the TOC changed from significantly positively related to correlation is not obvious, that algal density mainly absorb carbon source for the solubility inorganic carbon, main produce product for organic matter, and the solubility of organic carbon have a synthetic effect on algae growth. DIC and DO a significant negative correlation, were very significant negative correlation with temperature. Comprehensive excluding other factors, CAA and TIC, DTC, DIC, p H, TN, algal density. Controlled by the carbon source of algal density can control the release of the DOC, also can be controlled by controlling the TN carbonic anhydrase activity which affects the growth of algae. |
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