生物质炭对土壤中重金属生物有效性及其形态分布的影响研究

发布时间：2018-08-28 17:30

【摘要】：近年来,随着工农业生产的迅速发展,越来越多的农业耕作土壤受到重金属的污染。重金属进入土壤后难以降解,容易在土壤中积累并通过植物进入食物链,对人类健康造成威胁。作为一种新型的生物质资源,生物质炭可以作为土壤改良剂应用于修复土壤重金属污染,提高土壤肥力及作物产量。本研究选取竹炭和稻草炭为土壤改良剂,以Cd、Cu、Pb和Zn复合污染土壤为目标污染土壤。将生物质炭施加到重金属复合污染土壤中,在25oC条件下培养一年后,测定土壤pH、电导率、阳离子交换量、有效磷含量及CaCl2浸提态重金属含量的变化规律。同时测定土壤脲酶、过氧化氢酶、酸性磷酸酶的活性,分析土壤理化性质、重金属有效态含量及酶活性之间的相关性。目的在于确定生物质炭种类,用量(0、1%和5%)和粒径(1 mm和0.25 mm)对污染土壤中重金属生物有效性及形态分布的影响。以轻度重金属复合污染的土壤(Cd和Zn)为供试土壤,添加不同用量(0、1%、2.5%和5%)的烟秆炭和死猪炭后,移栽烟苗布置盆栽试验。试验结束后,测定烟草植株生物量和体内重金属积累量,检测土壤pH、电导率和重金属CaCl2浸提态重金属含量的变化。目的在于探究添加不同量的烟秆炭和死猪炭对烟草植株生长速率品质及土壤中重金属形态分布的影响,为进一步探讨利用生物质炭作为重金属污染土壤改良剂的可行性提供科学依据。主要研究结果如下:1.在重金属复合污染土壤中添加稻草炭可显著(p0.05)提高土壤pH、电导率、阳离子交换量和有效磷含量。土壤中添加稻草炭和竹炭均可降低土壤中CaCl2浸提态重金属含量,且对Cu和Pb的作用效果优于Cd和Zn。与竹炭相比,稻草炭的效果更佳。另外,5%用量处理效果优于1%处理,在5%细粒径稻草炭处理下,土壤中有效态的Cd和Zn降幅最大,分别达97.3%和62.2%。土壤中重金属有效态含量与土壤pH、水溶性有机碳和有效磷含量极显著(p0.01)负相关。土壤中添加生物质炭,尤其添加稻草炭后,可提高土壤脲酶和过氧化氢酶的活性。在5%粗、细粒径稻草炭处理下,脲酶活性分别提高143%和107%。两种酶的活性与4种重金属元素的有效态含量均呈极显著(p0.01)负相关。2.随烟秆炭和死猪炭施用量的增加,土壤pH逐渐升高,电导率无显著变化。土壤中CaCl2浸提态重金属含量随生物质炭添加量的增加逐渐降低,特别是在5%添加量处理下,烟秆炭对有效态Cd和Zn的降低量分别为64.2%和94.9%,死猪炭使其降低45.8%和61.8%。5%烟秆炭处理下,交换态Cd和Zn向碳酸盐结合态和铁锰氧化物结合态转化。随着死猪炭添加量的增加,交换态和碳酸盐结合态Cd向铁锰氧化物结合态转化,交换态和有机物结合态Zn向碳酸盐结合态和铁锰氧化物结合态转化,且添加越大转化效果越明显。添加生物质炭后,烟草植株地下部分生物量显著(p0.05)增大,且死猪炭添加量为2.5%时效果最佳,烟草地上部分和地下部分生物量分别增加43.5%和40.9%。添加两种生物质炭后,烟草地上部分和地下部分重金属积累量均显著(p0.05)降低。此外,Cd更易在地上部分富集,而地下部分含Zn量明显高于地上部分。综上所述,相比竹炭,稻草炭更适合作为土壤改良剂。不同类型、不同用量、不同粒径的生物质炭对土壤中重金属有效性和土壤酶活性的影响差异较大。烟秆炭对土壤中有效态重金属降低效果优于死猪炭,添加烟秆炭和死猪炭均可以提高烟草地下部分产量,降低重金属富集量。
[Abstract]:In recent years, with the rapid development of industry and agriculture, more and more agricultural soils are polluted by heavy metals. Heavy metals are difficult to be degraded when they enter the soil. They are easy to accumulate in the soil and enter the food chain through plants. As a new type of biomass resources, biomass carbon can be used as soil improvement. Bamboo charcoal and rice charcoal were selected as soil amendments and Cd, Cu, Pb and Zn were used as the target pollutants. Biochar was applied to the soil polluted by heavy metals and incubated under 25oC for one year. Soil pH, electrical conductivity and positive value were measured. Meanwhile, the activities of urease, catalase and acid phosphatase in soil were measured, and the physical and chemical properties of soil, the contents of available heavy metals and the correlation between enzyme activities were analyzed. Effects of 5 mm on bioavailability and speciation distribution of heavy metals in contaminated soils. Tobacco seedlings were planted in pots with different dosages of tobacco stalk charcoal (0,1,2.5% and 5%) and dead pig charcoal (0,1,2.5% and 5% respectively) in soils (Cd and Zn) which were slightly contaminated by heavy metals. The aim of this study was to investigate the effects of different amounts of tobacco stalk charcoal and dead pig charcoal on the growth rate and quality of tobacco plants and the distribution of heavy metals in soil, and to provide a basis for further exploring the feasibility of using biomass charcoal as a soil amendment for heavy metal pollution. The main results are as follows: 1. Adding straw charcoal to the soils polluted by heavy metals significantly (p0.05) increased soil pH, conductivity, cation exchange capacity and available phosphorus content. In addition, the effect of 5% treatment was better than that of 1%. Under the treatment of 5% fine-grained peat, the available cadmium and zinc in soil decreased by 97.3% and 62.2% respectively. The content of available heavy metals in soil was negatively correlated with soil pH, water-soluble organic carbon and available phosphorus (p0.01). The activity of urease and catalase were increased by 143% and 107% respectively under the treatments of 5% coarse and fine rice straw charcoal. The activity of urease and catalase was negatively correlated with the available content of four heavy metal elements (p0.01). 2. With the increase of the application amount of tobacco stalk charcoal and dead pig charcoal, the soil P The content of CaCl2 in soil decreased with the increase of biomass carbon. Especially under 5% addition, the content of available Cd and Zn decreased by 64.2% and 94.9% respectively, and that of dead pig charcoal decreased by 45.8% and 61.8% respectively. With the increase of carbon addition, exchangeable and carbonate-bound Cd transformed to iron-manganese oxide-bound state, exchangeable and organic-bound Zn transformed to carbonate-bound state and iron-manganese oxide-bound state, and the greater the addition, the more obvious the transformation effect was. The biomass of underground parts of tobacco plants increased significantly (p0.05), and the best effect was when the addition of dead pig charcoal was 2.5%. The biomass of above and below ground parts of tobacco plants increased by 43.5% and 40.9% respectively. In summary, compared with bamboo charcoal, straw charcoal is more suitable as soil amendment. Different types, dosages and sizes of biomass charcoal have different effects on the availability of heavy metals and soil enzyme activities. Tobacco stalk charcoal has better effect on reducing available heavy metals in soil than bamboo charcoal. Dead pig charcoal, tobacco stalk charcoal and dead pig charcoal can increase the yield of underground part of tobacco pasture and reduce the concentration of heavy metals.
【学位授予单位】：浙江农林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53

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