| Food quality and safety is related to the current China to improve the quality of agricultural products and enhance the level of agricultural industry is facing a major research topic,tea as China's characteristics of agricultural products,in the international market has a unique advantage and competitive potential,the international tea market competition gradually turned to quality and safety competition.At present,tea quality and safety of the main hazards,including pesticide residues,harmful heavy metal residues,harmful microbial contamination and sanitation and other four issues.With the increase of environmental problems,tea cultivation,processing and transportation,sales and other processes,the risk of heavy metal pollution,tea products,harmful heavy metal content exceeded the phenomenon occurred.To this end,tea heavy metal pollution has been widespread concern.In this paper,the differences of Cd,Pb,Hg,As and other heavy metals in different tea cultivars and different seasons were studied in different soils of different cadmium(Cd),lead(Pb),mercury(Hg)and arsenic(As).The differences of the leaching rates of four kinds of heavy metals were studied,and the contents of cadmium in soil and tea were analyzed.The main results were as follows:1.There was a significant positive correlation between the enrichment of heavy metal cadmium and the content of cadmium in the soil,indicating that the tea was affected by the cadmium content in the surface soil to a certain extent.The enrichment of heavy metal lead in tea was related to the heavy metal lead in the soil The results showed that the content of lead in tea was not positively correlated with the content of lead in soil.The correlation analysis between heavy metal mercury enrichment and heavy metal mercury content in tea was carried out.The results showed that There was no significant correlation between the absorption of mercury from the soil and the mercury content in the soil.The accumulation of arsenic in the tea was related to the content of arsenic in the soil.2.In this study,nine tea cultivars were selected from Hunan Province.The differences of enrichment ability of lead,cadmium,mercury and arsenic were analyzed.The results showed that the enrichment ability of heavy metals was found in heavy metal contaminated soil.Rich varieties of low tea varieties,Pittite early,Xiangbo green,Taoyuan big leaves these three varieties can be used as a low-heavy metal pollution in Hunan Province planting area.3.Based on the study of the differences in the enrichment of cadmium,lead,mercury and arsenic in the spring and summer seasons,the enrichment of four kinds of heavy metals in different seasons was analyzed.The contents of cadmium and arsenic in heavy metals were slightly increased with the variation of spring and summer,and the content of heavy metals in the three seasons did not change greatly.The contents of heavy metals were significantly decreased.4.In the experiment of leaching rate,the results showed that the leaching rates of four heavy metals were As> Hg> Pb> Cd,and the highest leaching rate was 52.2% in 51 min,51.2 %,27.1%,11.2%.With the prolongation of immersion time,the leaching rate of four kinds of heavy metals showed an increasing trend.In the flushing test,the leaching rate of four kinds of heavy metals in tea was proportional to the amount of water used in brewing.The leaching rate of the four kinds of heavy metals showed the same flushing rate as As> Hg> Pb> Cd.In addition,although the leaching rate of four kinds of heavy metals increases with the increase of flushing amount,the increase rate is not large.Compared with the brewing time of tea,the leaching rate of heavy metal cadmium,lead,mercury and arsenic The impact is not very significant.5.The contents of cadmium in the soil and the cadmium content of the tea samples were not exceeded after the analysis of soil samples and tea samples in Changsha,Ningxiang and Pingjiang counties.This also shows that the existing tea production is safe. |
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