【作者】 宋雁辉；

【导师】 王宏镔；

【作者基本信息】 昆明理工大学 ， 生态学， 2012， 硕士

【摘要】 随着采矿、选矿和冶炼行业的发展,农药、化肥和污灌的使用,使本已稀缺的耕地资源因土壤重金属污染而日益紧缺,土壤重金属污染已经严重制约污染区的农业发展,危及到农作物食品安全和人体健康。在土壤重金属难以快速、安全、经济去除的客观事实下,探寻低吸收作物种类或者品种在污染区推广种植,并通过土壤改良措施抑制土壤重金属向植物体迁移,是一条在污染区发展可持续农业生产的现实途径。本研究首先对云南个旧乍甸农田土壤和农作物进行野外调查,初步探明研究地点土壤基本理化性质以及农田土壤和农作物重金属污染现状,并根据不同作物对重金属的转移系数,筛选出低吸收品种或种类；然后在室内土培条件下,通过三因素四水平正交设计L16(43),研究外源As-Pb-Cd复合污染对甘蓝(Brassica oleracea L.)、芫荽(Coriandrum sativum L.)、油菜(Brassica napus L.)3种农作物的生物量、营养品质和可食部分重金属含量的影响；最后在室内土培条件下,以油菜(B. napus L.)为供试植物,直接以污染区农田土壤为供试土壤,通过添加不同浓度有机肥(鸡粪)、磷肥(NaH2PO4·2H2O)和有机肥与磷肥混施,研究不同改良剂对供试土壤基本理化性质、土壤酶活性、油菜可食部分As、Pb、Cd含量和营养品质的影响。研究的主要结果表明：(1)研究地点农田土壤Pb、Zn、Cu,、Cd、 As含量均超出《土壤环境质量标准》(GB15618-1995)二级标准,Hg未检出,该地区农田呈以As、Cd为主多种重金属复合污染。Pb、Zn、Cu、Cd、As土壤有效态含量与土壤全量呈极显著正相关(P<0.01)。农作物中Cu、As含量与土壤有效态Cu、As含量无显著相关,Zn含量与土壤有效态Zn呈极显著负相关(P<0.01),Cd、Pb含量与土壤有效态Cd、Pb呈显著正相关(P<0.05)。(2)89%的农作物As超标,其中油菜籽(B. napus L.) As含量最高,均值达23.04±14.33mg·kg-1(鲜重,下同)；Pb超标率达72%,油菜籽Pb含量最高,平均为5.55±2.53mg·kg-1; Zn、Cd超标率均为11.11%,超标最严重的油菜籽Zn含量为46.65±13.61mg·kg-1,Cd含量为0.24±0.10mg·kg-1;Cu超标率为5.55%,油菜籽Cu含量最高,达16.02±2.75mg·kg-1。油菜籽对As、Pb、Zn、Cu、Cd的转移系数[农作物可食部分重金属含量(鲜重)与土壤重金属含量的比值]远高于其他作物。农作物对Pb、Zn、Cd和As的转移顺序为果实类>叶菜类>根茎类,对Cu的转移顺序是果实类>根茎类>叶菜类。农作物以As、Pb污染为主,总体属重度污染。聚类分析得出油菜籽、青蒜(Allium ampeloprasum L.)和生菜(Lactuca sativa L. var. ramosa Hort.)重金属污染严重,不适合在该地区继续种植和食用。(3) As-Pb-Cd复合污染条件下,As低污染(50mg·kg-1)及Cd中污染(10mg·kg-1)刺激芫荽生长,重金属高污染均严重抑制3种作物的生长。16个浓度设置中,甘蓝、芫荽、油菜分别有18.75%、43.75%和50%3种元素同时超标。复合污染下重金属联合作用的类型因植物和元素种类而异。甘蓝对As、Cd的吸收,芫荽对Pb、Cd的吸收,油菜对As、Pb的吸收,表现为独立作用；As高污染(200mg·kg-1)促进了甘蓝Pb的吸收,As中污染(100mg·kg-1)促进了油菜Cd的吸收,表现为协同作用；As高污染(200mg·kg-1)抑制了油菜对Cd的吸收,表现为拮抗作用。As-Pb-Cd复合污染对3种植物可食部分维生素C、可溶性蛋白、游离氨基酸含量未有显著影响(P>0.05),唯有As显著增加甘蓝可溶性糖含量(P<0.05),但所设As浓度间无显著差异。本研究表明农作物的生物量、品质和重金属含量受作物种类、重金属组合及其浓度的影响。(4)土壤改良实验结果表明,所有改良处理均提高土壤pH值,供试土壤由中性变为碱性；土壤全氮和速效磷含量均大幅提升,土壤全氮由国家标准第五等级变为第三等级,土壤缺氮情况明显改善；除磷肥50mg·kg-1处理外,其余处理均增加土壤有机质含量；改良处理对阳离子交换量(CEC)无显著影响。所有处理均降低了土壤As有效态含量,当磷肥为200mg·kg-1时土壤As有效态含量最低,为90.42±1.21mg·kg-1;2/3的处理组显著降低了Cd有效态含量,其中磷肥和有机肥混施(50mg·kg-1+50g·kg-1)效果最佳；改良处理对降低土壤Pb有效态含量无显著差异。(5)所有处理均提高了土壤蔗糖酶和脲酶的活性,当磷肥和有机肥混施(200mg·kg-1+50g·kg-1)时,蔗糖酶和脲酶活性最高；当磷肥和有机肥混施(50mg·kg-1+50g·kg-1)时,显著增加过氧化氢酶活性；当有机肥75g·kg-1时,显著增加过氧化物酶活性。改良处理对降低油菜可食部分As含量作用明显,其次是Cd含量,油菜As、Cd含量均低于国家重金属限量标准,但对抑制Pb含量效果不佳。所有改良处理均增加油菜可食部分可溶性蛋白含量,当有机肥75g·kg-1、磷肥与有机肥混施(50mg·kg-1+50g·kg-1)时效果最佳；当有机肥75g·kg-1时,油菜可溶性糖含量最高；油菜可食部分维生素C含量无显著差异。本研究表明,施用改良剂能极大地改善土壤基本理化性质,不同程度地减少土壤As、Cd有效态含量,增加土壤酶活性,有效降低油菜可食部分As、Cd含量,提高油菜可溶性蛋白和可溶性糖含量。更多还原

【Abstract】 The scarce cultivated land is facing with severe reduction due to the development of mining, mineral separation and smelting as well as the usage of pesticides, chemical fertilizer and sewage irrigation. Heavy metal pollution of soil becomes a restraint of agricultural development and threat to food safety and physical health. Based on the fact of the difficulties of rapid, safe and economic removal of heavy metals, promoting the plantation of crops with low absorption in the polluted areas seems to a safe and practical way for the sustainable development of agriculture.The present paper took Zhadian Town, Gejiu City, Yunnan, as a case study sample for investigation and assessment of the heavy-metal pollution in farming crop-soil system in the multi-metal mining area. According to heavy metal transfer coefficient of various species of crops, we selected the breeds with low metal absorption. Through the way of the three factors and four levels orthogonal design L16(43), we conducted a research on the effect of As-Pb-Cd compounded pollution on the growth, biomass, quality and heavy metal concentrations in edible parts of Brassica oleracea L., Coriandrum sativum L. and Brassica napus L. under the laboratory condition. In addition, we also studied the basic physical and chemical properties, soil enzyme activity as well as the contents of As, Pb and Cd in plants by cultivating B. napus L. in the polluted soil with appliance of organic fertilizer (fowl dung), phosphatic fertilizer (NaH2PO4·2H2O) and the mixture of them. The main results are listed as follows:(1) The soil concentrations of heavy metals, including lead (Pb), zinc (Zn), copper (Cu), cadmium (Cd) and arsenic (As), all exceeded the Environmental Quality Standard for Soils (GB15618-1995)(Grade Ⅱ). Among them, mercury (Hg) could not be detected and the soil was mainly polluted by As and Cd. The concentrations of soil bioavailable Pb, Zn, Cu, Cd and As were significantly positively correlated with their total concentrations, respectively (P<0.01), but no significant correlation could be found between Cu and As concentrations in crops and those in soil’s crop-growing availability. A significant correlation was found among the crop Zn (negative), Cd (positive), Pb (positive) and soil bioavailable Zn, Cd and Pb, respectively.(2) The concentrations of As in89%of crops exceeded the maximal limit of contaminants in food. The higher concentrations of As was found in B. napus L., with an average of23.04±14.33mg·kg-1(fresh weight, the same as seen below). The exceeding rate of Pb was72%, and B. napus L. also had the highest concentration of Pb, with an average of5.55±2.53mg·kg-1. The exceeding rate of Zn or Cd was11.11%, whereas the maximum concentrations of Zn and Cd were observed in B. napus L., with an average of46.65±13.61mg·kg-1and0.24±0.10mg·kg-1, respectively. At the same time, the total exceeding rate of Cu was5.55%and the highest concentrations was detected in B. napus L., with an average of16.02±2.75mg·kg-1. The transfer ability of Pb, Zn, Cd and As in crops followed an order of fruit>leaf> root vegetables, whereas Cu was fruit>root> leaf vegetables. The crops were mainly polluted by As and Pb, and presented as severe pollution. The results of cluster analysis indicated that B. napus L., Allium ampeloprasum L. and Lactuca sativa L. var. ramosa Hort. were not fit for planting and/or used as human-consumptive crops because of their high-level metal translocation coefficients.(3) The results of orthogonal test showed that low pollution of As (50mg·kg-1) and Cd pollution (10mg·kg-1) stimulated the growth of C. sativum L., but the growth of three crops were severely inhibited when their concentrations increased. The exceeding rates of three heavy metals in the three crops were18.75%,43.75%and50%, respectively. The types of combined action of metals under compounded pollution differed from the plant species and metal elements. The absorption of As and Cd in B. oleracea L., Pb and Cd in C. sativum L. as well as As and Pb in B. napus L proved to be independent. On the contrary, a synergistic action was found in Pb and Cd absorption of B. oleracea L and B. napus L. when high (200mg·kg-1) and medium (100mg·kg-1) As was added, respectively. In addition, high concentration of As (200mg·kg-1) suppressed Cd absorption of B. napus L., showing an antagonism action. The As-Pb-Cd compounded pollution had no remarkable effects on the concentrations of vitamin C, soluble protein and free amino acids in edible parts of three crops (P>0.05). Arsenic could increase content of soluble sugar in B. oleracea L. remarkably (P<0.05) and there was no significant difference among different As concentrations. Therefore, the biomass, quality and contents of heavy metals in crops were affected by plant species, metal composition and their concentrations.(4) The results of soil ameliorative experiment showed that all of ameliorations enhanced pH value of soil and turned neutral to alkaline. The contents of total N and available P increased, and total N ranked from the third to the fifth national level. Therefore, deficiency of N was remarkably improved. The content of soil organic matter increased in all treatments except50mg·kg-1additon of phosphate fertilizer. The cation exchange capacity (CEC) was not significantly affected by ameliorative treatments. All the treatments decreased the content of available As and it got the lowest (90.42±1.21mg·kg-1) when the concentration of phosphate fertilizer was200mg·kg-1Furthermore, two third of treated groups significantly decreased the contents of bioavailabel Cd, and the combined addition of phosphate fertilizer (50mg·kg-1+50g·kg-1) and organic fertilizer (50g·kg-1) achieved the best results. The ameliorative treatments had no significance effect on reducing bioavailable Pb in soil.(5) All ameliorative treatments increased the activities of sucrase and urease and they reached the highest level under the combined treatments of phosphate fertilizer and organic fertilizer (200mg·kg-1+50g·kg-1). At the same time, the activities of catalase in soil increased significantly by combined addition of phosphate fertilizer and organic fertilizer (50mg·kg-1+50g·kg-1). The activities of peroxidase significantly increased when the organic fertilizer concentration was75g·kg-1. The ameliorative treatments significantly decreased the concentrations of As and Cd in edible parts of B. napus L., but not the concentrations of Pb. In addition, all of ameliorative treatments increased the content of soluble protein in edible part of B. napus L, and it became very effective when the concentration of organic fertilizer was75g·kg-1or combined addition of the phosphate fertilizer and organic fertilizer together (50mg-·kg-1+50g·kg-1). Meanwhile, soluble sugar content reached the highest level when the addition of organic fertilizer was75g·kg-1. No significant difference was observed in contents of vitamin C in edible part of B. napus L.. The present research showed that the application of soil amelioration materials could improve soil physical and chemical properties, decrease the concentrations of bioavailable As and Cd, increase the activities of soil enzymes, decrease the concentrations of As and Cd in edible parts of B. napus L. and increase the contents of soluble protein and soluble sugar of this plant.更多还原