土壤pH和Cd全量对伴矿景天修复效率的影响
|
摘要
修复效率是影响植物修复周期和技术推广的主要因素之一.采用不同pH和不同程度Cd污染农田土壤进行盆栽试验,其中,重度Cd污染土壤(简称"SKS处理")中w(Cd)(Cd全量)高于GB 15618—2018《土壤环境质量农用地土壤污染风险管控标准(试行)》中的风险管控值,中度Cd污染土壤(通过人为调节并稳定其pH为3. 97、4. 97、6. 03、6. 90和7. 93)中w(Cd)介于GB 15618—2018风险筛选值和管控值之间,轻度Cd污染土壤(简称"YH处理")中w(Cd)略高于GB 15618—2018风险筛选值;比较修复前后不同pH和不同程度Cd污染对土壤Cd有效性、形态分配及w(Cd)的影响,并结合PCA(主成分分析)和Pearson相关性分析等方法深入研究影响植物修复效率的主控因素.结果表明:①与修复前相比,不同pH处理修复后土壤中w(有效态Cd)、w(弱酸提取态Cd)、w(可还原态Cd)、w(可氧化态Cd)和w(Cd)的减少量均随pH的降低而增加,土壤pH≤6. 0时,伴矿景天修复效率显著高于土壤p H>6. 0的处理(P<0. 05).②修复后,轻度Cd污染土壤中w(Cd)降至GB 15618—2018风险筛选值以下,中度Cd污染土壤pH≤6. 0的处理中w(Cd)降至0. 60 mg/kg左右,而pH>6. 0的处理中w(Cd)仍高于1. 00 mg/kg.③重度Cd污染土壤中w(有效态Cd)最高,其伴矿景天生物量与轻度Cd污染土壤处理无显著差异,w(Cd)达681. 5 mg/kg,但修复效率显著低于其他处理(P<0. 05).综合PCA和Pearson相关性分析发现,影响伴矿景天修复效率的主控因素除土壤pH、Cd有效性和伴矿景天生物量外,伴矿景天的BCF(富集系数)对修复效率也具有重要作用.因此,伴矿景天更适用于弱酸性、中度Cd污染和轻度Cd污染土壤;而对碱性或重度Cd污染土壤进行植物修复时,可适当延长修复周期或联合修复以提高其修复效率.
Remediation efficiency is one of the main factors affecting the remediation cycle and promotion of remediation technology. Pot experiments were carried out with paddy soil with different pH and different Cd concentration. The w( Cd) of heavily contaminated soil( SKS) was much higher than the risk intervention value in Soil Environmental Quality Risk Control Standard for Soil Contamination of Agricultural Land( GB 15618-2018). The w( Cd) of moderately contaminated soil( pH were adjusted and stabilized to about 3. 97,4. 97,6. 03,6. 90 and 7. 93,respectively) was between the risk screening value and intervention value,and the w( Cd) of lightly contaminated soil( YH) was slightly higher than the risk screening value. The soil Cd availability,speciation distribution and w( Cd) before and after treatments at different pH and different Cd concentration were compared,and the main factors affecting the remediation efficiency were further studied by PCA and Pearson correlation analysis. The results showed that:( 1) Compared with the original soil,the decrement of the w( available Cd),w( acid soluble Cd),w( reducible Cd),w( oxidizable Cd) and the w( Cd) of the treated soil with different pH increased with decrease of pH. When p H≤6. 0,the remediation efficiency was significantly improved compared with the treatments of p H>6. 0( P<0. 05).( 2) After remediation,the w( Cd) of YH decreased to below the risk screening value. The w( Cd) with soil pH≤6. 0 of moderately contaminated soil was reduced to 0. 60 mg/kg,while the w( Cd) with soil pH> 6. 0 was still higher than 1. 00 mg/kg.( 3) The soil of SKS treatment had the highest w( available Cd),and there was no significant difference in biomass between SKS and YH,the w( Cd) of Sedum plumbizincicola could reach 681. 5 mg/kg,but the remediation efficiency was significantly lower than other treatments( P<0. 05). Taking into account the results of the PCA and Pearson correlation analysis,in addition to soil pH,Cd availability and the biomass,the bio-concentration factor( BCF) of S. plumbizincicola also played an important role in the efficiency of remediation.Therefore,phytoremediation with S. plumbizincicola is more suitable for the moderately and lightly Cd-contaminated and acid soils,while for phytoremediation of alkaline or heavily contaminated soils,the remediation cycle can be extended or the efficiency could be improved by combining other remediation techniques.
Remediation efficiency is one of the main factors affecting the remediation cycle and promotion of remediation technology. Pot experiments were carried out with paddy soil with different pH and different Cd concentration. The w( Cd) of heavily contaminated soil( SKS) was much higher than the risk intervention value in Soil Environmental Quality Risk Control Standard for Soil Contamination of Agricultural Land( GB 15618-2018). The w( Cd) of moderately contaminated soil( pH were adjusted and stabilized to about 3. 97,4. 97,6. 03,6. 90 and 7. 93,respectively) was between the risk screening value and intervention value,and the w( Cd) of lightly contaminated soil( YH) was slightly higher than the risk screening value. The soil Cd availability,speciation distribution and w( Cd) before and after treatments at different pH and different Cd concentration were compared,and the main factors affecting the remediation efficiency were further studied by PCA and Pearson correlation analysis. The results showed that:( 1) Compared with the original soil,the decrement of the w( available Cd),w( acid soluble Cd),w( reducible Cd),w( oxidizable Cd) and the w( Cd) of the treated soil with different pH increased with decrease of pH. When p H≤6. 0,the remediation efficiency was significantly improved compared with the treatments of p H>6. 0( P<0. 05).( 2) After remediation,the w( Cd) of YH decreased to below the risk screening value. The w( Cd) with soil pH≤6. 0 of moderately contaminated soil was reduced to 0. 60 mg/kg,while the w( Cd) with soil pH> 6. 0 was still higher than 1. 00 mg/kg.( 3) The soil of SKS treatment had the highest w( available Cd),and there was no significant difference in biomass between SKS and YH,the w( Cd) of Sedum plumbizincicola could reach 681. 5 mg/kg,but the remediation efficiency was significantly lower than other treatments( P<0. 05). Taking into account the results of the PCA and Pearson correlation analysis,in addition to soil pH,Cd availability and the biomass,the bio-concentration factor( BCF) of S. plumbizincicola also played an important role in the efficiency of remediation.Therefore,phytoremediation with S. plumbizincicola is more suitable for the moderately and lightly Cd-contaminated and acid soils,while for phytoremediation of alkaline or heavily contaminated soils,the remediation cycle can be extended or the efficiency could be improved by combining other remediation techniques.
引文
[1] UDOVIC M,DROBNE D,LESTAN D.Bioaccumulation in Porcellio scaber(Crustacea,Isopoda)as a measure of the EDTA remediation efficiency of metal-polluted soil[J].Environmental Pollution,2009,157(10):2822-2829.
[2] GRAY C W,MCLAREN R G,ROBERTS A H C,et al.Sorption and desorption of cadmium from some New Zealand soils:effect of pH and contact time[J].Australian Journal of Soil Research,1998,36:199-216.
[3]杨文弢,周航,邓贵友,等.组配改良剂对污染稻田中铅、镉和砷生物有效性的影响[J].环境科学学报,2016,36(1):257-263.YANG Wentao,ZHOU Hang,DENG Guiyou,et al. Effect of combned amendment on bioavailability of Pb,Cd and As in polluted paddy soil[J].Acta Science Circumstantiae,2016,36(1):257-263.
[4]廖敏,黄昌勇,谢正苗.pH对镉在土水系统中的迁移和形态的影响[J].环境科学学报,1999,19(1):83-88.LIAO Min,HUANG Changyong,XIE Zhengmiao. Effect of p H on transport and transformation of cadmium in soil water system[J].Acta Science Circumstantiae,1999,19(1):83-88.
[5] BOEKHOLD A E,TEMMINGHOFF E J M.Influence of electrolyte composition and pH on cadmium sorption by an acid sandy soil[J].European Journal of Soil Science,2010,44(1):85-96.
[6]杨忠芳,陈岳龙,钱鑂,等.土壤pH对镉存在形态影响的模拟试验研究[J].地学前缘,2005,12(1):252-260.YANG Zhongfang,CHEN Yuelong,QIAN Xun,et al.A study of the effect of soil pH on chemical species of cadmium by simulated experiments[J].Earth Science Frontiers,2005,12(1):252-260.
[7] AUDET P,CHAREST C. Heavy metal phytoremediation from a meta-analytical perspective[J].Environmental Pollution,2007,147(1):231-237.
[8] LI Z,WU L H,LUO Y M,et al.Dynamics of plant metal uptake and metal changes in whole soil and soil particle fractions during repeated phytoextraction[J].Plant Soil,2014,374(1/2):857-869.
[9] LIU W T,ZHOU Q X,ZHANG Y L,et al. Lead accumulation in different Chinese cabbage cultivars and screening for pollution-safe cultivars[J].Journal of Environmental Management,2010,91(3):781-788.
[10] WU L H,ZHOU J W,ZHOU T,et al. Estimating cadmium availability to the hyperaccumulator,Sedum plumbizincicola,in a wide range of soil types using a piecewise function[J]. Science of the Total Environment,2018,637/638:1342-1350.
[11] MA Y,RAJKUMAR M,LUO Y M,et al.Phytoextraction of heavy metal polluted soils using Sedum plumbizincicola inoculated with metal mobilizing Phyllobacterium myrsinacearum RC6b[J].Chemosphere,2013,93(7):1386-1392.
[12] GUO F H,ZHONG Z P,XUE H.Partition of Zn,Cd,and Pb during co-combustion of Sedum plumbizincicola and sewage sludge[J].Chemosphere,2018,197:50-56.
[13]王一志,曹雪莹,谭长银,等.不同土壤pH对红壤稻田镉形态及水稻镉积累的影响[J].湖南师范大学自然科学学报,2017,40(1):10-16.WANG Yizhi,CAO Xueying,TAN Changyin,et al.Effects of differet soil pH on cadmium fractions and cadmium accumulation in rice[J].Journal of Natural Science of Hunan Normal University,2017,40(1):10-16.
[14]鲍士旦.土壤农化分析[M].北京:中国农业出版社,2005.
[15]曹雪莹.湘中镉污染酸性红壤的钝化修复研究[D].长沙:湖南师范大学,2015.
[16] MEHLICH A.New extractant for soil test evaluation of phosphorus,potassium,magnesium,calcium,sodium,manganese and zinc[J].Communications in Soil Science and Plant Analysis,1978,9(6):477-492.
[17] LUO Y M,CHRISTIE P. Choice of extraction technique for soil reducible trace metals determines the subsequent oxidizable metal fraction in sequential extraction schemes[J]. International Journal of Environmental Analytical Chemistry,1998,72(1):59-75.
[18]唐琨,朱伟文,周文新,等.土壤pH对植物生长发育影响的研究进展[J].作物研究,2013,27(2):207-212.TANG Kun,ZHU Weiwen,ZHOU Wenxin,et al. Research progress on effects of soil pH on plant growth and development[J]. Crop Research,2013,27(2):207-212.
[19] LIANG H M,LIN T H,CHIOU J M,et al.Model evaluation of the phytoextraction potential of heavy metal hyperaccumulators and non-hyperaccumulators[J]. Environmental Pollution,2009,157(6):1945-1952.
[20] DEGRYSE F,SMOLDERS E,ZHANG H,et al. Predicting availability of mineral elements to plants with the DGT technique:a review of experimental data and interpretation by modelling[J].Environmental Chemistry,2009,6(3):198-218.
[21]刘芸君,钟道旭,李柱,等.锌镉交互作用对伴矿景天锌镉吸收性的影响[J].土壤,2013,45(4):700-706.LIU Yunjun,ZHONG Daoxu,LI Zhu,et al.Interaction of Zn and Cd on heavy metal phytoextraction efficiency of Sedum plumbizincicola[J].Soils,2013,45(4):700-706.
[22]李思亮,李娜,徐礼生,等.不同生境下锌镉在伴矿景天不同叶龄叶中的富集与分布特征[J].土壤,2010,42(3):446-452.LI Siliang,LI Na,XU Lisheng,et al. Characters of Zn and Cd accumulation and distribution in leaves of Sedum plumbizincicola at different ages[J].Soils,2010,42(3):446-452.
[23]李娜,吴龙华,骆永明,等.收获方式对污染土壤上伴矿景天锌镉吸收性的影响[J].土壤学报,2009,46(4):725-728.LI Na,WU Longhua,LUO Yongming,et al. Effects of harvesting way of Sedum plumbizincicola on its zinc and cadmium uptake in a mixed heavy metal contaminated soil[J]. Acta Pedologica Snica,2009,46(4):725-728.
[24] LI Z,WU L H,HU P J,et al. Repeated phytoextraction of four metal-contaminated soils using the cadmium/zinc hyperaccumulator Sudum plumbizincicola[J]. Environmental Pollution,2014,189(12):176-183.
[25]何其辉,谭长银,曹雪莹,等.肥料对土壤重金属有效态及水稻幼苗重金属积累的影响[J].环境科学研究,2018,31(5):942-951.HE Qihui,TAN Changyin,CAO Xueying,et al. Effects of fertilizer on the availability of heavy metals in soil and its accumulation in rice seedling[J]. Research of Environmental Sciences,2018,31(5):942-951.
[26] FARZADSAR G D,SHARKEY T D. Stomatal conductance and photosynthesis[J]. Annual Review of Plant Physiology,1982,33:317-345.
[27] APPEL C,MA L.Concentration,pH,and surface charge effects on cadmium and lead sorption in three tropical soils[J]. Journal of Environmental Quality,2002,31(2):581-589.
[28]李造煌,杨文弢,邹佳玲,等.钙镁磷肥对土壤Cd生物有效性和糙米Cd含量的影响[J].环境科学学报,2017,37(6):2322-2330.LI Zaohuang,YANG Wentao,ZOU Jialing,et al. Effects of calcium magnesium phosphate fertilizer on Cd bioavailability in soil and Cd contents in rice[J]. Acta Scientiae Circumstantiae,2017,37(6):2322-2330.
[29] KANTER U,HAUSER A,MICHALKE B,et al. Caesium and strontium accumulation in shoots of Arabidopsis thaliana:genetic and physiological aspects[J]. Journal of Experimental Botany,2010,61(14):3995-4009.
[30] SOLTI A,SARVARI E,T·OTH B,et al.Cd affects the translocation of some metals either Fe-like or Ca-like way in poplar[J]. Plant Physiology and Biochemistry,2011,49(5):494-498.
[31]汪洪,周卫,林葆.钙对镉胁迫下玉米生长及生理特性的影响[J].植物营养与肥料学报,2001,7(1):78-87.WANG Hong,ZHOU Wei,LIN Bao. Effects of Ca on growth and some physiological characteristics of maize under Cd stress[J].Plant Nutrition and Fertilizer Science,2001,7(1):78-87.
[32] JACKSON D A.Stopping rules in principal components analysis:a comparison of heuristical and statistical approaches[J]. Ecology,1993,74(8):2204-2214.
[33] ZONG Wei,MA Kai,CHEN Zhiyuan,et al. Heavy metals in soils and road dusts in the mining areas of western Suzhou,China:a preliminary identification of contaminated sites[J]. Journal of Soils and Sediments,2016,16(1):204-214.
[34] MA Li,YANG Zhaoguang,LI Lei,et al.Source indentification and risk assessment of heavy metal contaminations in urban soils of Changsha,a mine-impacted city in southern China[J].Environmental Science and Pollution Research,2016,23(17):17058-17066.
[35]张慧,郑志志,马鑫鹏,等.哈尔滨市土壤表层重金属污染特征及来源辨析[J].环境科学研究,2017,30(10):1597-1606.ZHANG Hui,ZHENG Zhizhi,MA Xinpeng,et al. Sources and pollution characteristics of heavy metals in surface soils of Harbin City[J].Research of Environmental Sciences,2017,30(10):1597-1606.
[2] GRAY C W,MCLAREN R G,ROBERTS A H C,et al.Sorption and desorption of cadmium from some New Zealand soils:effect of pH and contact time[J].Australian Journal of Soil Research,1998,36:199-216.
[3]杨文弢,周航,邓贵友,等.组配改良剂对污染稻田中铅、镉和砷生物有效性的影响[J].环境科学学报,2016,36(1):257-263.YANG Wentao,ZHOU Hang,DENG Guiyou,et al. Effect of combned amendment on bioavailability of Pb,Cd and As in polluted paddy soil[J].Acta Science Circumstantiae,2016,36(1):257-263.
[4]廖敏,黄昌勇,谢正苗.pH对镉在土水系统中的迁移和形态的影响[J].环境科学学报,1999,19(1):83-88.LIAO Min,HUANG Changyong,XIE Zhengmiao. Effect of p H on transport and transformation of cadmium in soil water system[J].Acta Science Circumstantiae,1999,19(1):83-88.
[5] BOEKHOLD A E,TEMMINGHOFF E J M.Influence of electrolyte composition and pH on cadmium sorption by an acid sandy soil[J].European Journal of Soil Science,2010,44(1):85-96.
[6]杨忠芳,陈岳龙,钱鑂,等.土壤pH对镉存在形态影响的模拟试验研究[J].地学前缘,2005,12(1):252-260.YANG Zhongfang,CHEN Yuelong,QIAN Xun,et al.A study of the effect of soil pH on chemical species of cadmium by simulated experiments[J].Earth Science Frontiers,2005,12(1):252-260.
[7] AUDET P,CHAREST C. Heavy metal phytoremediation from a meta-analytical perspective[J].Environmental Pollution,2007,147(1):231-237.
[8] LI Z,WU L H,LUO Y M,et al.Dynamics of plant metal uptake and metal changes in whole soil and soil particle fractions during repeated phytoextraction[J].Plant Soil,2014,374(1/2):857-869.
[9] LIU W T,ZHOU Q X,ZHANG Y L,et al. Lead accumulation in different Chinese cabbage cultivars and screening for pollution-safe cultivars[J].Journal of Environmental Management,2010,91(3):781-788.
[10] WU L H,ZHOU J W,ZHOU T,et al. Estimating cadmium availability to the hyperaccumulator,Sedum plumbizincicola,in a wide range of soil types using a piecewise function[J]. Science of the Total Environment,2018,637/638:1342-1350.
[11] MA Y,RAJKUMAR M,LUO Y M,et al.Phytoextraction of heavy metal polluted soils using Sedum plumbizincicola inoculated with metal mobilizing Phyllobacterium myrsinacearum RC6b[J].Chemosphere,2013,93(7):1386-1392.
[12] GUO F H,ZHONG Z P,XUE H.Partition of Zn,Cd,and Pb during co-combustion of Sedum plumbizincicola and sewage sludge[J].Chemosphere,2018,197:50-56.
[13]王一志,曹雪莹,谭长银,等.不同土壤pH对红壤稻田镉形态及水稻镉积累的影响[J].湖南师范大学自然科学学报,2017,40(1):10-16.WANG Yizhi,CAO Xueying,TAN Changyin,et al.Effects of differet soil pH on cadmium fractions and cadmium accumulation in rice[J].Journal of Natural Science of Hunan Normal University,2017,40(1):10-16.
[14]鲍士旦.土壤农化分析[M].北京:中国农业出版社,2005.
[15]曹雪莹.湘中镉污染酸性红壤的钝化修复研究[D].长沙:湖南师范大学,2015.
[16] MEHLICH A.New extractant for soil test evaluation of phosphorus,potassium,magnesium,calcium,sodium,manganese and zinc[J].Communications in Soil Science and Plant Analysis,1978,9(6):477-492.
[17] LUO Y M,CHRISTIE P. Choice of extraction technique for soil reducible trace metals determines the subsequent oxidizable metal fraction in sequential extraction schemes[J]. International Journal of Environmental Analytical Chemistry,1998,72(1):59-75.
[18]唐琨,朱伟文,周文新,等.土壤pH对植物生长发育影响的研究进展[J].作物研究,2013,27(2):207-212.TANG Kun,ZHU Weiwen,ZHOU Wenxin,et al. Research progress on effects of soil pH on plant growth and development[J]. Crop Research,2013,27(2):207-212.
[19] LIANG H M,LIN T H,CHIOU J M,et al.Model evaluation of the phytoextraction potential of heavy metal hyperaccumulators and non-hyperaccumulators[J]. Environmental Pollution,2009,157(6):1945-1952.
[20] DEGRYSE F,SMOLDERS E,ZHANG H,et al. Predicting availability of mineral elements to plants with the DGT technique:a review of experimental data and interpretation by modelling[J].Environmental Chemistry,2009,6(3):198-218.
[21]刘芸君,钟道旭,李柱,等.锌镉交互作用对伴矿景天锌镉吸收性的影响[J].土壤,2013,45(4):700-706.LIU Yunjun,ZHONG Daoxu,LI Zhu,et al.Interaction of Zn and Cd on heavy metal phytoextraction efficiency of Sedum plumbizincicola[J].Soils,2013,45(4):700-706.
[22]李思亮,李娜,徐礼生,等.不同生境下锌镉在伴矿景天不同叶龄叶中的富集与分布特征[J].土壤,2010,42(3):446-452.LI Siliang,LI Na,XU Lisheng,et al. Characters of Zn and Cd accumulation and distribution in leaves of Sedum plumbizincicola at different ages[J].Soils,2010,42(3):446-452.
[23]李娜,吴龙华,骆永明,等.收获方式对污染土壤上伴矿景天锌镉吸收性的影响[J].土壤学报,2009,46(4):725-728.LI Na,WU Longhua,LUO Yongming,et al. Effects of harvesting way of Sedum plumbizincicola on its zinc and cadmium uptake in a mixed heavy metal contaminated soil[J]. Acta Pedologica Snica,2009,46(4):725-728.
[24] LI Z,WU L H,HU P J,et al. Repeated phytoextraction of four metal-contaminated soils using the cadmium/zinc hyperaccumulator Sudum plumbizincicola[J]. Environmental Pollution,2014,189(12):176-183.
[25]何其辉,谭长银,曹雪莹,等.肥料对土壤重金属有效态及水稻幼苗重金属积累的影响[J].环境科学研究,2018,31(5):942-951.HE Qihui,TAN Changyin,CAO Xueying,et al. Effects of fertilizer on the availability of heavy metals in soil and its accumulation in rice seedling[J]. Research of Environmental Sciences,2018,31(5):942-951.
[26] FARZADSAR G D,SHARKEY T D. Stomatal conductance and photosynthesis[J]. Annual Review of Plant Physiology,1982,33:317-345.
[27] APPEL C,MA L.Concentration,pH,and surface charge effects on cadmium and lead sorption in three tropical soils[J]. Journal of Environmental Quality,2002,31(2):581-589.
[28]李造煌,杨文弢,邹佳玲,等.钙镁磷肥对土壤Cd生物有效性和糙米Cd含量的影响[J].环境科学学报,2017,37(6):2322-2330.LI Zaohuang,YANG Wentao,ZOU Jialing,et al. Effects of calcium magnesium phosphate fertilizer on Cd bioavailability in soil and Cd contents in rice[J]. Acta Scientiae Circumstantiae,2017,37(6):2322-2330.
[29] KANTER U,HAUSER A,MICHALKE B,et al. Caesium and strontium accumulation in shoots of Arabidopsis thaliana:genetic and physiological aspects[J]. Journal of Experimental Botany,2010,61(14):3995-4009.
[30] SOLTI A,SARVARI E,T·OTH B,et al.Cd affects the translocation of some metals either Fe-like or Ca-like way in poplar[J]. Plant Physiology and Biochemistry,2011,49(5):494-498.
[31]汪洪,周卫,林葆.钙对镉胁迫下玉米生长及生理特性的影响[J].植物营养与肥料学报,2001,7(1):78-87.WANG Hong,ZHOU Wei,LIN Bao. Effects of Ca on growth and some physiological characteristics of maize under Cd stress[J].Plant Nutrition and Fertilizer Science,2001,7(1):78-87.
[32] JACKSON D A.Stopping rules in principal components analysis:a comparison of heuristical and statistical approaches[J]. Ecology,1993,74(8):2204-2214.
[33] ZONG Wei,MA Kai,CHEN Zhiyuan,et al. Heavy metals in soils and road dusts in the mining areas of western Suzhou,China:a preliminary identification of contaminated sites[J]. Journal of Soils and Sediments,2016,16(1):204-214.
[34] MA Li,YANG Zhaoguang,LI Lei,et al.Source indentification and risk assessment of heavy metal contaminations in urban soils of Changsha,a mine-impacted city in southern China[J].Environmental Science and Pollution Research,2016,23(17):17058-17066.
[35]张慧,郑志志,马鑫鹏,等.哈尔滨市土壤表层重金属污染特征及来源辨析[J].环境科学研究,2017,30(10):1597-1606.ZHANG Hui,ZHENG Zhizhi,MA Xinpeng,et al. Sources and pollution characteristics of heavy metals in surface soils of Harbin City[J].Research of Environmental Sciences,2017,30(10):1597-1606.