| The tea is Chinese important economic crops, their quality problems not onlyrelated to the development of the tea industry in China and income of80millionfarmers, but also affects people’s physical health. In recent years, reports of the teaquality continue to emerge.Heavy metal pollution in tea is one of the main qualityproblems emerged in recent years. The soil is an important source of heavy metals intea. Soil is an important part of the environmental elements, and bears about90%ofthe environmental pollutants from all sides. With the development of industrialization,urbanization, more and more pollutants are released into the soil, the soil becomesmainly place where heavy metals accumulate.Heavy metals enter the body of peopleby "soil-plant-human" way and produce a potential threat to human health. When theaccumulation of heavy metals exceed the maximum limits of the human body canbear, there are bound to endanger human health.This study selected the representative tea plantations in mountainous area ofsouthern Anhui to collect the samples of soil and tea. And soil properties (pH, organicmatter, water content), the heavy metal content of the soil and tea (Mg, Al, Fe, Mn, Cr,Cu, Zn, As, Pb, Ni) were analyzed. Focus on soil-tea system heavy metal migrationcharacteristics of tea under different altitudes, different planting years, different slope,and assess the soil-tea system for health risk in mountainous area of southern Anhui.Mainly the following conclusions:(1)By the evaluation criteria of the soil background value in mountainous area ofsouthern Anhui area, As was belonging to the heavily polluted and Cu was belongingto the moderately polluted, Zn, Mn, Ni and Cr were belonging to the slightly polluted,Pb was belonging to the non-polluting in soil of mountainous area of southern Anhui,the comprehensive pollution index was5.619, belonging to the heavily pollution. Bythe evaluation criteria of the China Environmental Quality Standard for Soils(GB15618-1995, Grade II) contamination, As was belonging to the light pollution,and other elements were belonging to the non-polluting, comprehensive pollutionindex was1.268, belonging to the light pollution. (2)The heavy metal content were quite different between the old leaves and theyoung leaves. Compared with other cities, the content of As in the young leaves inmountainous area of southern Anhui was relatively high, which was probably theapplication of pesticides and fertilizers. By the limited value of the evaluation criteriaof tea quality grading standards (GB9679-88) and heavy metals in tea health standard,Cu and Pb were belonging to the non-polluting. Cr and As in young leaves werebelonging to the non-polluting. Cr in old leaves had been a certain degree of pollution,and As pollution was more serious. The exceeded rate of old leaves was more than theexceeded rate of young leaves. The comprehensive pollution index of young leaveswas0.447, belonging to the security level; the comprehensive pollution index of oldleaves was1.458, belonging to the light pollution.(3)Heavy metals of tea at different altitudes had little difference. The impact ofplanting years to the content of heavy metals in old leaves was greater than youngleaves. The content of all elements in the old tea which planting years were more than40years were higher than those which planting years were less than40years, exceptMg. The content of Mn, Fe, Ni, Cr and As in the young tea which planting years weremore than40years were higher than those which planting years were less than40years. But the features of Al, Mg, Zn, Cu and Pb were on the contrary. In general, thecontent of heavy metals in the tea which slop less than35°were higher than thosewhich slop more than35°. In addition to Mn, Fe, Ni,content of the other sevenelements in the old tea which slop less than35°were higher than those which slopmore than35°. In addition to Mn, Ni,content of the other eight elements in the youngtea which slop less than35°were higher than those which slop more than35°.(4)The enrichment factors of all elements in tea in Mountainous area of southernAnhui were less than1, except Mn. There was a strong enrichment ability of tea toMn. The enrichment factors of old leaves and young leaves to Cu and Zn wererelatively high, the enrichment factors of old leaves and young leaves to Al and Fewere relatively low. Old leaves and young leaves had large differences in enrichmentability of different metal elements.(5)The altitude has only an impact on the enrichment factors of the individualmetal elements. Enrichment factors only of Mn and Cu, Cr had relatively largedifferences at different altitudes in old leaves; enrichment factors only of Mn, Cu hadrelatively large differences at different altitudes in the leaves. The enrichment factorsof tea which had different planting years had large differences. The enrichmentfactors of all elements in old leaves which planting years were more than40yearswere higher than those which planting years were less than40years, except Mg. Theenrichment factors of all elements in young leaves which planting years were morethan40years were higher than those which planting years were less than40years, except Pb. Accumulation ability of heavy metals in the steep slope region wasstronger than that which was in a small slope region. The enrichment factors of allelements in old leaves and young leaves which slop more than35°were higher thanthose which slop less than35°, except Pb.(6) Relevance between heavy metals in young leaves and heavy metals in soiland relevance between heavy metals in old leaves and heavy metals in soil were quitedifferent. The content of Ni in young leaves and the content of Ni in soil weresignificantly correlated. The content of Mg, Ni in old leaves and the content of Mg, Niin soil were significantly correlated. The source of Ni in tea was closely related to thecontent of Ni in soil. Al, Mn in young leaves and pH of soil was significantlynegatively correlated, Cr in old leaves and pH of soil was significantly negativelycorrelated. Any elements in young leaves and old leaves and organic matter, watercontent did not show significant correlation.(7) The order of adult average on-carcinogenic exposure to heavy metals of soilby three different ways were all hand-mouth intake ways>skin inhalationmeans>breath inhalation channel. Eight kinds of heavy metals in soil of adults indifferent ways of non-carcinogenic exposure risk index HQ were lower than1, andhand-mouth intake ways exposed the greatest risk, skin inhalation means followed,breath inhalation channel minimum. HI of non-carcinogenic risk of heavy metals wereall less than1, the risk of a variety of heavy metals in the superposition ofmulti-channel intake was up to0.226, indicating that the health risks of combinedpollution of heavy metals was also relatively small. The carcinogenic risk of threeheavy metals were much lower than the carcinogenic risk threshold range (10-6-10-4),indicating that lower carcinogenic risk would not cause a health hazard.(8) As and Cr of chemical carcinogens via ingestion pathway to cause healthhazards of personal annual risk, in order to Cr (1.08×10-4) the biggest, As (4.35×10-6)followed. Zn and Cu of non-chemical carcinogens via ingestion pathway to causehealth hazards of personal annual risk, in order to Cu (2.06×10-8) the biggest, Zn(1.64×10-9) followed. Non-chemical carcinogens caused health hazards of personaltotal annual risk of approximately2.23×10-8. By chemical carcinogenic heavy metalsand chemical non-carcinogenic heavy metals via ingestion pathway to caused healthhazards of personal total annual risk of approximately1.12×10-4. The health risks ofheavy metals of tea in tea garden of Mountainous area of southern Anhui were mainlyfrom chemical carcinogenesis heavy metals. |
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