牟婷婷(1991—),女,黑龙江肇东人,博士,主要从事土壤和作物重金属污染与修复研究。E-mail:
选取我国主要农作区的33个典型土壤,开展了两个常规小麦品种(蓉麦4号(RM4)和山农22号(SN22))的盆栽试验,研究了土壤–小麦体系内Cd的积累特征,并探究了相关土壤主控因子。结果表明:RM4和SN22两个品种小麦籽粒Cd含量分别为0.21(0.040 ~ 0.99)mg/kg和0.18(0.037 ~ 0.70)mg/kg,据GB 2762—2017,Cd超标率分别为75.6% 和69.7%;小麦籽粒Cd的生物富集系数(BCF)分别为0.92(0.24 ~ 2.55)和0.81(0.16 ~ 1.67),均表现出较强的Cd富集能力。多元逐步回归和广义Boosted模型分析发现,土壤全Cd和pH是影响小麦籽粒Cd吸收的主控因子,分别解释33个土壤中变量的81.3% 和80.5%。
Two main wheat cultivars (RM4 and SN22) were planted in thirty-three typical soils collected in the main rice-wheat rotation regions in China to investigate the characteristics of cadmium (Cd) translocation in soil-wheat systems and the major controlling factors. The results show that Cd concentration in wheat grains is 0.21(0.040–0.99)mg/kg for RM4 and 0.18(0.037–0.70)mg/kg for SN22, and the percentage of exceeding Cd limit (GB 2762—2017) is 75.6% for RM4 and 69.7% for SN22. The bio-concentration factor (BCF) of Cd in wheat grains is 0.92(0.24–2.55)for RM4 and 0.81(0.16–1.67)for SN22, respectively, both showing strong ability of accumulating Cd. Multiple stepwise regression analysis and Generalized Boosted Models(GBM)indicate that soil Cd concentration and pH are the two most important variables which influencing Cd accumulation in wheat grains, which explain 81.3% and 80.5% among five soil variables of the thirty-three soils.
小麦是全球第三大粮食作物,也是我国第二大粮食作物,在我国粮食作物的生产和消费中占主导地位。我国的小麦种植区域主要集中在长江中下游及其以北地区,包括河北、河南、湖北、四川、山东、安徽和江苏等地。相比于水稻,我国小麦镉(Cd)污染的研究较少。作为食物链的起点,小麦也会吸收土壤中的有毒元素,并通过食物链传递危害人体健康。调查发现江苏省稻麦轮作体系下,在全Cd含量为0.481(0.278 ~ 1.10)mg/kg的农田土壤中,小麦籽粒Cd含量为0.130(0.043 ~ 0.621)mg/kg[
目前,重金属Cd在土壤–小麦系统的积累和传递已有较多研究[
本研究拟以我国主要农作区的33个典型农田土壤为供试材料,分别种植两个常规小麦品种,探明两个小麦品种在不同土壤类型上的Cd吸收性,以比较不同类型土壤上两个品种小麦籽粒Cd的积累特征,探明土壤性质对小麦籽粒Cd吸收的影响,并探究影响小麦籽粒Cd吸收的土壤主控因子,建立基于土壤性质的不同品种小麦籽粒Cd浓度的预测模型,并评价模型的不确定性。本研究可为小麦实际生产过程中存在的Cd污染问题提供新的认识,相关研究成果也可指导小麦的安全生产。
2015年在我国水稻优势产区共采集33个耕层水稻土(0 ~ 20 cm)。采样点位分别位于黑龙江、吉林、辽宁、山东、河南、陕西、宁夏、安徽、江苏、浙江、湖北、湖南、江西、云南、广西、福建和贵州。供试土壤的pH、有机碳(SOC)、CEC、黏粒、全Cd含量平均值分别为6.31、21.1 g/kg、12.4 cmol/kg、221 g/kg、0.26 mg/kg。土壤基本理化性质变异较大,pH变化在强酸性到弱碱性。与GB 15618—2018《土壤环境质量农用地土壤污染风险管控标准》(试行)[
供试土壤风干过2 mm尼龙网筛、装盆,每盆土重2 kg。小麦品种选择蓉麦4号(RM4)和山农22号(SN22)。小麦种植前每盆施0.6 g CO(NH2)2和0.6 g K2H2PO4作为基肥。小麦种子浸泡在5% NaClO中消毒20 min,然后将种子催芽3 d后,每盆播种15粒,待长出幼苗后进行间苗,每盆定苗8株。小麦拔节期后、灌浆期前每盆施用0.4 g Na2H2PO4、0.4 g KCl和0.6 g CO(NH2)2作为追肥。小麦生长过程中,不同的盆栽随机排列,并定期重新排列位置。小麦于2017年11月15日播种,2018年5月18日收获。小麦成熟后收获麦穗,晒干后脱壳,得到小麦籽粒(全麦)。小麦籽粒带回实验室,用自来水清洗3次,再用蒸馏水清洗3次后,转移至烘箱以70 ℃烘至恒重,用粉碎机打成细粉末,待测。
土壤pH以土水比1:2.5(
本研究利用多元逐步回归分析方法,建立基于土壤pH、全Cd、CEC、SOC和黏粒含量的小麦籽粒Cd含量预测模型。GBM(generalized boosted models)分析是一种根据数据变量的类型,利用自适应算法自动估算大量混杂变量与处理变量之间非线性关系的一种分析方法,特别是当变量之间线性、非线性或交互关系等函数形式无法确定时,此方法具有明显优势。本研究通过GBM分析,量化土壤性质对小麦籽粒Cd积累的贡献,获得所选土壤性质对小麦籽粒Cd含量的相对重要性和偏相关分析图。该分析利用gbm软件包在R 3.2.2统计环境中进行。同时本研究还采用迭代方法,将预测误差较大的变量通过序列迭代组合成预测性能较好的强化模型,并通过比较盆栽试验中测定的小麦籽粒Cd含量与模型预测的Cd含量,确定模型预测的精度。
小麦和土壤中Cd的单项污染指数计算:
式中:[Cd测]代表样品中Cd含量实测值;[Cd标]代表土壤和小麦籽粒中Cd含量标准值,其中,土壤参考GB 15618—2018[
小麦籽粒Cd的生物富集系数(BCF):小麦籽粒Cd含量和对应土壤Cd含量的比值。
文中数据利用Microsoft Excel 2016和SPSS 21.0进行整理和统计分析, 采用单因素方差分析法(One- way ANOVA)对土壤和小麦籽粒样品中Cd含量以及BCF的差异性进行检验(
如
不同类型土壤下小麦籽粒镉含量和富集系数变化
Cd concentrations and bioconcentratiuon factor (BCF) values of wheat grains in different soil types
此外,两个品种小麦的Cd生物富集系数(BCF)分别是0.92(0.24 ~ 2.55)和0.81(0.16 ~ 1.67)。RM4和SN22小麦籽粒对Cd的BCF最大值分别为是2.55和1.67,其对应的土壤分别采自广东江门(pH 5.50)和云南德宏(pH 6.22)的酸性土壤;BCF最小值分别是0.24和0.16,其对应的土壤均为采自江苏连云港的碱性土壤(pH 8.94)。通过分析两个品种小麦籽粒Cd的BCF可发现,RM4和SN22的BCF > 1的样品数分别是14个和9个,说明小麦是一种对Cd富集能力较强的作物。主要原因是小麦籽粒Cd的积累主要是通过根部富集后运输到旗叶韧皮部再进入籽粒,即小麦植株内较强的Cd转运能力导致其籽粒Cd大量积累[
本研究基于土壤pH、CEC、SOC、黏粒含量以及全量Cd等基本性质,采用逐步回归分析方法建立了小麦籽粒Cd含量预测模型(
基于土壤基本性质和全量镉的小麦籽粒镉含量多元逐步回归预测方程(
Multiple regression models for Cd concentration in wheat grains based on soil basic properties and total Cd
品种 | 回归方程 | SE | ||
RM4 | log[Cd麦] = 0.655 × log[Cd土] − 0.394 | 0.41 | 0.000 | 0.24 |
log[Cd麦] = 0.726 × log[Cd土] − 0.167 × pH + 0.707 | 0.77 | 0.000 | 0.15 | |
SN22 | log[Cd麦] = 0.644 × log[Cd土] − 0.345 | 0.42 | 0.000 | 0.22 |
log[Cd麦] = 0.716 × logCd土] − 0.171 × pH + 0.782 | 0.82 | 0.000 | 0.12 |
文献报道的关于小麦籽粒镉含量预测模型
Models found in literatures to predict Cd concentration in wheat grains
模型 | 参考文献 | SE | ||
log[Cd麦] = 0.824 log[Cd土] − 0.383 | Zhou等[ |
26 | 0.38 | 0.23 |
log[Cd麦]= 0.44 log[Cd土] − 0.18 pH + 0.28 | Adams等[ |
162 | 0.42 | 0.23 |
log[Cd麦] = log[Cd土] − 0.279 pH + 1.386 | Liu等[ |
14 | 0.45 | 0.029 |
log[Cd麦] = 1.04 log[Cd土] − 0.175 pH + 0.703 | Ran等[ |
99 | 0.44 | 0.038 |
log[Cd麦]= 0.749 log[Cd土] − 0.257 pH − 0.277 Log[SOM] + 1.022 | Brus等[ |
84 | 0.44 | 0.041 |
通过绘制盆栽小麦籽粒Cd含量的预测值和相应的实测值组成的散点图(
小麦籽粒镉含量实测值和预测值比较
Relationship between measured and predicted Cd concentrations in wheat grains
本研究利用GBM分析土壤全Cd、pH、SOC、CEC和黏粒含量对两个品种小麦籽粒Cd积累的相对重要性和贡献率。首先,对上述土壤变量(除pH外)进行对数转换,以保证方差的齐性。如
土壤性质对小麦籽粒镉含量的贡献率及偏相关分析
Relative contribution and partial dependency plots for soil properties influencing Cd concentrations in wheat grains
小麦籽粒Cd的转运和积累受土壤性质(pH、Eh和CEC)、小麦品种(基因型差异)和农艺措施(水分和施肥管理)等的共同影响[
本试验中小麦籽粒Cd含量超标情况不容忽视,应重视小麦籽粒Cd含量的超标风险。土壤性质是影响小麦Cd吸收的重要因素,其中土壤全量Cd和pH是影响小麦籽粒Cd含量的重要变量,分别解释33个土壤中变量的81.3% 和80.5%。本研究结果为小麦实际生产中存在的Cd污染问题提供了指导,通过预测影响小麦Cd吸收的土壤主控因子,可为小麦的安全生产提供技术指导。
Zhou Y J, Jia Z Y, Wang J X, et al. Heavy metal distribution, relationship and prediction in a wheat-rice rotation system[J]. Geoderma, 2019, 354: 113886.
Wang C, Ji J F, Yang Z F, et al. Effects of soil properties on the transfer of cadmium from soil to wheat in the Yangtze River Delta region, China—a typical industry-agriculture transition area[J]. Biological Trace Element Research, 2012, 148(2): 264–274.
中华人民共和国国家卫生和计划生有委员会, 国家食品药品监督管理总. 《食品安全国家标准食品中污染物限量》: GB 2762—2017[S]. 北京: 中国标准出版社, 2017.
肖冰, 薛培英, 韦亮, 等. 基于田块尺度的农田土壤和小麦籽粒镉砷铅污染特征及健康风险评价[J]. 环境科学, 2020, 41(6): 2869–2877.
Shi G L, Zhu S, Bai S N, et al. The transportation and accumulation of arsenic, cadmium, and phosphorus in 12 wheat cultivars and their relationships with each other[J]. Journal of Hazardous Materials, 2015, 299: 94–102.
Adams M L, Zhao F J, McGrath S P, et al. Predicting cadmium concentrations in wheat and barley grain using soil properties[J]. Journal of Environmental Quality, 2004, 33(2): 532–541.
Liu K, Lv J, He W, et al. Major factors influencing cadmium uptake from the soil into wheat plants[J]. Ecotoxicology and Environmental Safety, 2015, 113: 207-213.
Wu J, Norvell W A, Hopkins D G, et al. Spatial variability of grain cadmium and soil characteristics in a durum wheat field[J]. Soil Science Society of America Journal, 2002, 66(1): 268–275.
Zhang S Z, Wang S X, Shan X Q, et al. Influences of lignin from paper mill sludge on soil properties and metal accumulation in wheat[J]. Biology and Fertility of Soils, 2004, 40(4): 237–242.
Zhao K L, Liu X M, Xu J M, et al. Heavy metal contaminations in a soil-rice system: Identification of spatial dependence in relation to soil properties of paddy fields[J]. Journal of Hazardous Materials, 2010, 181(1/2/3): 778–787.
Liu Y Z, Xiao T F, Baveye P C, et al. Potential health risk in areas with high naturally-occurring cadmium background in southwestern China[J]. Ecotoxicology and Environmental Safety, 2015, 112: 122–131.
Ran J, Wang D J, Wang C, et al. Heavy metal contents, distribution, and prediction in a regional soil-wheat system[J]. Science of the Total Environment, 2016, 544: 422–431.
Brus D J, de Gruijter J J, Römkens P F A M. Probabilistic quality standards for heavy metals in soil derived from quality standards in crops[J]. Geoderma, 2005, 128(3/4): 301–311.
生态环境部, 国家市场监督管理总局土壤环境质量农用地土壤污染风险管控标准(试行): GB 15618—2018[S]. 北京: 中国标准出版社, 2018.
鲍士旦. 土壤农化分析[M]. 3版. 北京: 中国农业出版社, 2000.
Zhang M K, Liu Z Y, Wang H. Use of single extraction methods to predict bioavailability of heavy metals in polluted soils to rice[J]. Communications in Soil Science and Plant Analysis, 2010, 41(7): 820–831.
蔡保松, 张国平. 大、小麦对镉的吸收、运输及在籽粒中的积累[J]. 麦类作物学报, 2002, 22(3): 82–86.
Gray C W, Yi Z C, Munir K, et al. Cadmium concentrations in new Zealand wheat: Effect of cultivar type, soil properties, and crop management[J]. Journal of Environmental Quality, 2019, 48(3): 701–708.
Fairbrother A, Wenstel R, Sappington K, et al. Framework for metals risk assessment[J]. Ecotoxicology and Environmental Safety, 2007, 68(2): 145–227.
Wångstrand H, Eriksson J, Öborn I. Cadmium concentration in winter wheat as affected by nitrogen fertilization[J]. European Journal of Agronomy, 2007, 26(3): 209–214.
Yu H Y, Liu C P, Zhu J S, et al. Cadmium availability in rice paddy fields from a mining area: The effects of soil properties highlighting iron fractions and pH value[J]. Environmental Pollution, 2016, 209: 38–45.
Guo F Y, Ding C F, Zhou Z G, et al. Effects of combined amendments on crop yield and cadmium uptake in two cadmium contaminated soils under rice-wheat rotation[J]. Ecotoxicology and Environmental Safety, 2018, 148: 303–310.
Li D Q, Li W Y, Lu Q, et al. Cadmium bioavailability well assessed by DGT and factors influencing cadmium accumulation in rice grains from paddy soils of three parent materials[J]. Journal of Soils and Sediments, 2018, 18(7): 2552–2561.
Hamid Y, Tang L, Yaseen M, et al. Comparative efficacy of organic and inorganic amendments for cadmium and lead immobilization in contaminated soil under rice-wheat cropping system[J]. Chemosphere, 2019, 214: 259–268.
Wang A S, Angle J S, Chaney R L, et al. Soil pH effects on uptake of Cd and Zn by
Chen H Y, Yuan X Y, Li T Y, et al. Characteristics of heavy metal transfer and their influencing factors in different soil-crop systems of the industrialization region, China[J]. Ecotoxicology and Environmental Safety, 2016, 126: 193–201.
He Y B, Huang D Y, Zhu Q H, et al. A three-season field study on the
Yang J L, Cang L, Wang X, et al. Field survey study on the difference in Cd accumulation capacity of rice and wheat in rice-wheat rotation area[J]. Journal of Soils and Sediments, 2020, 20(4): 2082–2092.
Wenzel W W, Blum W E H, Brandstetter A, et al. Effects of soil properties and cultivar on cadmium accumulation in wheat grain[J]. Zeitschrift Für Pflanzenernährung Und Bodenkunde, 1996, 159(6): 609–614.
Bolan N S, Adriano D C, Duraisamy P, et al. Immobilization and phytoavailability of cadmium in variable charge soils. III. Effect of biosolid compost addition[J]. Plant and Soil, 2003, 256(1): 231–241.
Welch R M, Norvell W A. Mechanisms of Cadmium Uptake, Translocation and Deposition in PlantsCadmium in Soils and Plants, 1999: 125–150.
François M, Grant C, Lambert R, et al. Prediction of cadmium and zinc concentration in wheat grain from soils affected by the application of phosphate fertilizers varying in Cd concentration[J]. Nutrient Cycling in Agroecosystems, 2009, 83(2): 125–133.
Liu L N, Chen H S, Cai P, et al. Immobilization and phytotoxicity of Cd in contaminated soil amended with chicken manure compost[J]. Journal of Hazardous Materials, 2009, 163(2/3): 563–567.
Laing G D, Rinklebe J, Vandecasteele B, et al. Trace metal behaviour in estuarine and riverine floodplain soils and sediments: A review[J]. Science of the Total Environment, 2009, 407(13): 3972–3985.
Impellitteri C A, Lu Y F, Saxe J K, et al. Correlation of the partitioning of dissolved organic matter fractions with the desorption of Cd, Cu, Ni, Pb and Zn from 18 Dutch soils[J]. Environment International, 2002, 28(5): 401–410.