| Uranium(U)is characterized by long half-life,fever and heavy metal toxicity.Under the action of long-term weathering and leaching,uranium and other harmful substances in uranium tailings will migrate to the surrounding open water and underground water.Once in an organism,their potential hazards persist.They can accumulate in organism through food chain,cause internal radiation damage,cause species variation,and endanger local drinking water safety,residents' health and ecological environment.Therefore,it is of great significance to study the migration,accumulation and chemical transformation of uranium in the water environment.This paper is to study the migration and chemical transformation of uranium along the chlorella-blue zebrafish water ecological food chain by simulating a food chain.The first stage is the culture of chlorella and the second stage is the toxicity exposure of algae cells.To analyze the effects of uranium on algal cell density,morphology,chlorophyll,etc.In the third stage,the blue zebrafish were fed and exposed,and uranium in the system was further carried out by ICP-MS,SR-?-XRF and XNAES.Analysis and research provide a basis for the prevention and risk assessment of uranium pollution.The main findings are as follows:Chlorella was exposed to uranium concentrations of 0.5,1,2,5,10,20,40 mg/L for 3 weeks,uranium concentration<20 mg/L,and algae cells survived normally.Uranium concentration>40 mg/L,algae cells inactivated and died.The morphology of algae cells was analyzed by SEM.The algal cells in the blank group were well-formed and spherical.The uranium concentration was?2 mg/L.The algae cells were intact and the cell surface was shrinking.The uranium concentration was>2 mg/L.Deformation,surface shrinkage.Chlorophyll content is associated with exposure to uranium concentrations over long-term exposure,independent of exposure time.The uranium concentration was 1 mg/L.When exposed for 3 weeks,the contents of chlorophyll,chlorophyll a and b were the highest in algae cells,which were 2.86,1.70 and 1.16 mg/g,respectively.When the uranium concentration is 40 mg/L,the chlorophyll content is about zero.ICP-MS showed that the gluten of 2 mg/L and 20 mg/L uranium had the highest accumulation on the 5th day,which were 78.52 and 53.80 mg/g,respectively.Zebra fish mortality test results in uranium toxicity test:zebrafish in the food exposure group(chlorella after exposure to 2 mg/L+uranium containing 2 mg/L in water)had a mortality rate of up to 100%after 3 weeks,blank group The mortality rate is at least 10%.ICP-MS showed that after culturing zebrafish for 2 weeks after exposure to 2 mg/L and 20 mg/L uranium,the visceral uranium accumulation was 12.74 and 279.27 ?g/g,respectively.The results showed that uranium could be in the food chain.Migration and accumulation,and in different ways(food exposure group,water environment exposure group,water environment and food exposure group),zebrafish can ingest uranium,but uranium accumulation is highest in water environment and food exposure group,uranium in muscle The accumulation amount is as high as 67.78 ?g/g.The results of SR-?-XRF experiments showed that the uranium in the food exposed group was mainly distributed in the viscera of the zebrafish,and the uranium in the water environment exposed group was mainly distributed in the bone and viscera of the zebrafish.XANES was used to determine that the uranium peaks in the exposed algae cells(days 5 and 30)and zebrafish tissues(water environment exposure group-fish-head,food exposure group-fish-visceral/muscle)were basically the same,but the peaks of the characteristic peaks were deviated,indicating that the absorption energy of the uranium was displaced,and the uranium migrated in the food chain and chemically converted. |
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