Uptake,Migration Of Perfluorocarboxylic Acid Compounds In Soybean (Glycine Max L.) Seedlings And Its Influencing Factors

Perfluoroalkyl acids（PFCAs）is a class of synthetic persistance organic pollutants.Because of its unique hydrophobic and oil-repellent properties,it has been widely used in industrial and daily life products since the 1950s,such as surfactants,refrigerants,lubricants,coatings,foam extinguishing agents and cosmetics.In recent years,a large number of fluorine chemical enterprises have moved to developing countries including China,so the exposure level of PFCAs in China’s environment is still at a relatively high level.Studies have shown that PFCAs can accumulate in crops through the soil-plant system and enter into organisms along the food chain,seriously threatening the quality and safety of agricultural products and human health.At present,there are few studies on the absorption and migration characteristics of PFCAs in crops,and the toxic effects of PFCAs on crops are not comprehensive enough.To solve this problem,soybean（Glycine Max L.）,an important food crop in China,was selected as the experimental material in this study.Four kinds of soybeans from different regions were selected in the experiment:Late ripening Pingding Huang,Wanhuang 506,Wild Soybean and Northeast Spring Soybean LS18.Under greenhouse hydroponic conditions,the absorption and migration of PFCAs with different carbon chain lengths in soybean seedlings were studied.On this basis,the toxic effect of PFCAs on soybean seedlings and the correlation between soybean crude protein content and the uptake of PFCAs were further explored.The main research results are as follows:1.Studies showed that when the stress concentration was 10 mg·L^-1,the absorption amount of PFCAs in soybean seedlings in each treatment group was higher than that in the 1mg·L^-1treatment group,and the absorption amount increased with the increase of stress days.Under the two concentration stress,the uptake of wild soybean was higher than that of LS18,Wanhuang and Late Maturing Pingding Huang（P<0.05）.PFCAs can be absorbed by soybean and migrated to the ground（stem and leaf）.PFCAs in the stem and leaf of soybean mainly originate from the root migration,with the highest uptake of PFOA in the root and the highest uptake of PFBA in the stem.2.The absorption process of PFCAs in soybean conforms to the first-order kinetic equation.According to the absorption rate constant k,the k value of PFCAs with different carbon chain lengths in soybean root,stem and leaf was k（PFHp A）>k（PFOA）>k（PFBA）in general.When the enrichment of PFCAs reached half,the time(t_1/2)consumed by soybean root,stem and leaf was as follows:t_1/2（PFBA）>t_1/2（PFHp A）>t_1/2（PFOA）.3.PFCAs at 1 mg·L^-1and 10 mg·L^-1promoted the growth of soybean seedlings.When the PFCAs stress concentration was 10 mg·L^-1,the enzymatic activities of POD,CAT and APX in soybean stems and leaves was decreased.4.Among the four different soybean varieties,the crude protein content in seeds and seed-lings of wild soybean was the highest（P<0.05）.Through further statistical analysis,it was found that the crude protein content in seeds and seedlings of soybean was positively cor-related with PFCAs uptake.