| Sr is one of the radioactive pollutants produced by atmosphere, underground nuclear testing or nuclear leakage accidents, and its radioactive effects last for a long time in the ecological environment. The reason is 90Sr pollutes water bodies by precipitation or water flow, or fall to the earth’s surface by atmospheric circulation with falling ash or wet deposition, and is being absorbed or enriched directly or indirectly by plants and animals. Thus, after a series of metabolic process in organisms and circulations at all levels in food chain,90Sr finally does internal and external irradiation harm to organisms at all levels.With the wide application of nuclear technology and enhanced awareness of environmental protection, comprehensive control and risk assessment of the pollution of Sr has become a hot issue in science. Several studies have found that the phytoremediation technology is likely to be an effective and feasible measure to control the heavy metal pollution to get some promotion and application in many fields. But due to the complexion of radioactive Sr in soil-plant system, and people still have an unknown about the absorption, transport, accumulation and poisoning mechanism of Sr, the study on this issue is necessary. In order to explore the transfer characteristic of radionuclide Sr in the soil-plant system, it is necessary to carry out further researches and analysis on characteristics of absorption or accumulation of Sr in different organizations of plants and their physiological and biochemical responses. From the perspectives of food safety, especially the packaging plant is closely related to people’s life and health. Therefore, we cannot ignore the harm and influence on food safety caused by Sr. In this study, stable nuclide 88Sr was used as the substitute of radionuclide 90Sr. Based on the pot experiment, four vegetables, including Chinese cabbage, celery, radish and pepper, were planted in the greenhouse. Sr concentrations in the plants and the soil were measured with the inductively coupled plasma atomic emission spectrometry (ICP-AES), and then the transportation factor (TF) of strontium and the concentration ratio (CR) of the different plants were calculated, and the activity of antioxidant enzymes was detected, to explore the absorption and accumulation characteristics of Sr in four kinds of common vegetables and the effects of Sr on their physiological indexes. The results are as follows:(1) The Sr concentration in soil had a significant effect on the concentration of Sr in different tissues of the four kinds of vegetables, including Chinese cabbage, celery, radish and pepper (P<0.05). Different vegetables had different performance on the absorption and accumulation of Sr, and the Sr concentration in different tissues of four kind of vegetables increased with the increasing of the Sr concentration in soil (P<0.05). Within the treatment contents of Sr in the experiment, with the increasing of the Sr concentration in soil, more Sr was absorbed in vegetables(P<0.05). Sr had an uneven distribution in four kinds of vegetables. For Chinese cabbage and radish, the concentration of Sr in the stem and leaves was higer than it in the roots (P<0.05). For celery and pepper, the concentration of Sr in the root was higher than that in the stem and leaves (P<0.05). The characteristics of absorption and enrichment of Sr in different types of crops showed significant differences(P<0.05).(2) The concentration of Sr in different tissues of the four kinds of vegetables was significantly influenced by the Sr concentration in soil (P>0.05). Different tissues of four kinds of vegetables showed different CR and TF value. Within the treatment contents of Sr in the experiment, the CR value of different tissues of Chinese cabbage showed:stem and leaves> root (P<0.05), the CR value of different tissues of radish showed:stem and leaves> root (P<0.05), the TF value of stem and leaves of the Chinese cabbage and radish showed: radish> Chinese cabbage (P<0.05), the CR value of celery showed: leaves> stem (P<0.05), the TF value of celery showed:leaves> stem (P<0.05), the CR value of pepper showed:root> leaf> stem> fruit (P<0.05), the TF value of pepper showed: leaf> stem> fruit (P<0.05).(3) With the increase of the concentration of Sr in soil, the chlorophyll content showed a trend of rise first, then fall in different tissues of four kind of vegetables (P<0.05). The low concentrations of Sr promoted the content of the chlorophyll to a certain extent. However, the high concentrations of Sr caused the inhibition of the content of the chlorophyll. The trend was the same with the change of the activity of the antioxidant enzyme POD, CAT and SOD (P<0.05). But there were some differences in the magnitude of changeof them in different tissues of vegetables. However, with the increase of contents of Sr, the MDA contents of leaves showed a trend of fall first, then rise (P<0.05). These results reflect the degree of cell damageand manifests that the low concentration of Sr stimulates the defense system, but the high concentration of Sr damages it. |
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