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    安溪茶园土壤团聚体组成及其对元素分配的影响

    Characteristics of soil aggregates of tea gardens in Anxi County, Fujian Province, and their influence on element distribution

    • 摘要: 在铁观音茶叶主产区福建省安溪县27个茶园采集了表层(0~20cm)和亚表层(20~40cm)土壤,风干过2mm筛后,采用超声振动筛进行筛分,并测定了粒级样品元素含量。结果表明:(1)2000~840μm和840~250μm的大团聚体颗粒占土壤样品重量的73%左右,而250~125μm、125~63μm和<63μm3种微团聚体约占27%;(2)大团聚体与微团聚体量的比值与土壤SiO2呈反比,与Al2O3、Fe2O3呈正相关,说明富含黏土矿物和铁铝氧化物有利于大团聚体颗粒的形成。土壤大团聚体与微团聚体中Cd、Cr、Hg、Ni、P、Al等多数元素指标的浓度差异明显,除了SiO2、Mn外,其他指标均不同程度地自粗粒级向细粒级逐渐增加,以P、Zn、Zr、Corg最为明显;(3)浸提实验表明,水提取态元素浓度最低,As、Cu、Pb、Zn浸提量由水提取-NH4NO3提取-稀盐酸提取-DTPA提取逐步增加;对于其他元素,稀盐酸提取态Cd、Se较高,NH4NO3提取态Mn、Ni较高,Hg则以NH4NO3提取态和DTPA浸提态较高。表层土壤中多数元素浸提浓度高于亚表层土壤,推断与表层土壤有机碳较高有关。

       

      Abstract: Top (0-20 cm)and sub-layer (20-40 cm)soils were collected at twenty-seven tea gardens in Anxi, Fujian Province, which is the source area for Tieguanyin tea production. Air-dried soils after sieving through 10 mesh (2 mm nylon screen) were partitioned into 5 aggregate-size fractions by vibration sieving with supersonic wave generators. It is found that the macro aggregates of 2000-840 μm and 840-250 μm fractions are composed of 73% of the total particle weight, and micro aggregates of 250-125 μm, 125-63 μm and <63 μm fractions occupy less than 30%. Soils with higher Al2O3, Fe2O3 and lower SiO2 are in favor of macro aggregate formation. There is a concentration difference between macro and micro aggregates for most elements such as Cd, Cr, Hg, Ni, P and Al. The concentrations of most geochemical indicators such as P, Zn, Zr and organic carbon become increasingly higher with the decrease of the aggregate size. Extractable concentrations of As, Cu, Pb and Zn are enhanced in order of water, ammonium nitrate, dilute hydrochloric acid, and DTPA extraction. However, the extractable Cd, Hg, Mn, Ni and Se present higher concentrations in the particular extraction method. Generally the extractable content of top soils is higher than that of sublayer soils due to soil physical-chemical characteristics including organic carbon content and soil structure.

       

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