Descriptive statistics of particle-size classes G1 - G6 (%), pH, TOC (%), ChE total concentrations and mobile fractions (mg/kg), and mobility of ChEs (%) in Chernozems and Planosols

Soil samples from the pits studiedwere analysed at the MSU (Lomonosov Moscow State University) Faculty of Geography by standard techniques. The analyses included total organic carbon (TOC), рН and the particle-size distribution. The Russian system of particle-size classes was used, i.e., G1 – clay (particles <1 µm), G2 – fine silt (1 – 5 µm), G3 – medium silt (5 – 10 µm), G4 – coarse silt (10 – 50 µm), G5 – fine sand (50 – 250 µm) and G6 – medium and coarse sand (250 – 1000 µm).
Total content of 24 ChEs was determined at the IGEM RAS (Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry of the Russian Academy of Sciences) using an Axios X-Ray fluorescence spectrometer (made by PANalytical, Netherlands) and Russian Soil Standard samples (SSs of ‘Chernozem’ and ‘Albeluvisol’),.
The analysed fractions of the ChEs were defined as follows:
• F1 – weakly bound acid-soluble (exchangeable ions readily available to plants),
• F2 – complexed (fulvate and humate substances potentially available to plants),
• F3 – bound with Fe and Mn hydroxides (unavailable to plants) and
• F4 – residual fraction.
Mobile fractions F1, F2 and F3 were obtained according to the extraction procedure by (Solov’ev, 1989) with the use of the following reagents: (1) F1 – with NH4Ac (ammonium acetate buffer) and the soil:solution ratio of 1:5, (2) F2 – with 1% EDTA (ethylenediaminetetraacetic acid) and the soil:solution ratio of 1:5 and (3) F1 and F3 – with 1M HNO3 (nitric acid) and the soil:solution ratio of 1:10. Soil suspensions (50 ml) were prepared from soil subsamples (5-10 g) by incubation for 18 hours.
Concentrations of the extracted ChEs (Al, As, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, Pb, Se, Si, Sr and Zn) in the filtrates were determined using an Elan-6100 ICP-MS System (Inductively Coupled Plasma Mass Spectrometer by PerkinElmer Inc., USA) and an Optima-4300 DV ICP-AES System (Inductively Coupled Plasma Atomic Emission Spectrometer by PerkinElmer Inc., USA) at the VIMS (N. M. Fedorovskii All-Russia Institute of Mineral Raw Materials).
The procedure (Solov’ev, 1989) is regularly used in Russian soil quality assessments for analysing mobile fractions of ChEs from polluted and background soils (Minkina et al., 2018; Siromlya, 2009). Another normality of NH4Ac, EDTA and HNO3 extracts is used all over the world (e.g., Anderson, 1976; Bakircioglu et al., 2011; Dudas and Pawluk, 1977; Kelepertzis et al., 2018; McBratney et al., 1982; Takeda et al., 2004; Torri and Lavado, 2009a, 2009b).
The ChE mobility is defined as a ratio of the element’s mobile fractions (F1+F2+F3) to its total content, multiplied by 100%.

本研究针对各研究坑采集的土壤样品，于莫斯科国立罗蒙诺索夫大学（Lomonosov Moscow State University, MSU）地理学院采用标准分析技术开展检测。检测指标包括总有机碳（total organic carbon, TOC）、pH值与颗粒粒径分布。本次分析采用俄罗斯粒径分级体系，具体分级为：G1——黏土（颗粒粒径<1 µm）、G2——细粉砂（1~5 µm）、G3——中粉砂（5~10 µm）、G4——粗粉砂（10~50 µm）、G5——细砂（50~250 µm）以及G6——中粗砂（250~1000 µm）。
24种化学元素（Chemical Elements, ChEs）的总含量于俄罗斯科学院矿石沉积、岩石学、矿物学与地球化学研究所（Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry of the Russian Academy of Sciences, IGEM RAS）完成测定，所用仪器为荷兰帕纳科（PANalytical）公司生产的Axios型X射线荧光光谱仪，同时采用俄罗斯土壤标准样品，即‘黑钙土’（Chernozem）与‘黏磐土’（Albeluvisol）标准样品进行质量控制。
本次分析定义的化学元素各结合态组分如下：
• F1——弱结合酸溶态（植物可直接获取的可交换离子），
• F2——络合态（植物潜在可利用的富里酸与腐殖酸结合物），
• F3——与铁、锰氢氧化物结合态（植物不可利用），
• F4——残留态。
可移动组分F1、F2与F3按照索洛维约夫（Solov’ev, 1989）提出的提取流程制备，所用试剂及土液比参数如下：(1) F1组分采用乙酸铵（NH4Ac）缓冲液，土液比为1:5；(2) F2组分采用1%乙二胺四乙酸（ethylenediaminetetraacetic acid, EDTA）溶液，土液比为1:5；(3) F1与F3组分采用1M硝酸（HNO3）溶液，土液比为1:10。称取5~10 g土壤子样品制备50 ml土壤悬浮液，经18小时振荡孵育后完成提取。
滤液中各提取态化学元素（Al、As、Ca、Cd、Co、Cr、Cu、Fe、K、Mg、Mn、Mo、Na、Ni、Pb、Se、Si、Sr与Zn）的浓度，于N. M. 费多罗夫斯基全俄矿物原料研究所（VIMS），采用美国珀金埃尔默（PerkinElmer Inc.）公司的Elan-6100型电感耦合等离子体质谱仪（Inductively Coupled Plasma Mass Spectrometer, ICP-MS）与Optima-4300 DV型电感耦合等离子体原子发射光谱仪（Inductively Coupled Plasma Atomic Emission Spectrometer, ICP-AES）完成测定。
索洛维约夫（1989）提出的提取方法已广泛应用于俄罗斯土壤质量评估工作，用于分析污染与背景土壤中化学元素的可移动组分（Minkina等, 2018；Siromlya, 2009）。乙酸铵、乙二胺四乙酸与硝酸提取体系的标准化规范已在全球范围内通用（如Anderson, 1976；Bakircioglu等, 2011；Dudas与Pawluk, 1977；Kelepertzis等, 2018；McBratney等, 1982；Takeda等, 2004；Torri与Lavado, 2009a、2009b）。
化学元素的迁移率定义为该元素可移动组分（F1+F2+F3）的含量与其总含量的比值，再乘以100%。