生活污泥改良滩涂土壤过程中重金属环境效应的探索研究

发布时间：2019-05-17 10:59

【摘要】：我国东部沿海滩涂是重要后备耕地资源,然而新围垦滩涂并非农用耕地,须投入大量有机物料加以熟化改良。我国符合农用标准的城市生活污泥有机质及养分含量高、粘性强,可作为滩涂土壤改良的廉价优质有机肥源。然而,施用生活污泥是否会增加滩涂土壤重金属的累积,是否会影响土壤重金属的活性,从而增加植物对重金属累积以及重金属污染环境的风险,几乎没有报道,这严重妨碍了资源化利用生活污泥改良滩涂土壤的实施。本研究采用符合农用标准的城市生活污泥为材料,通过田间试验、室内模拟、化学分析与生物学检测相结合的方法,深入探讨不同施用量(0、30、75、150、300t ha-1)的生活污泥改良滩涂土壤过程中,主要重金属在植物体内的累积、滩涂土壤主要重金属的形态转化特征、重金属在土壤剖面中的迁移特点等。结果表明：(1)施用生活污泥显著促进了滩涂土壤种植的绿肥植物(黑麦草、田菁、玉米、玉米幼苗)生长,同时增加重金属(Cd、Cu、Pb、Zn)的累积,积累的主要原因是植株体内重金属含量的提高。(2)施用生活污泥显著增加了滩涂土壤全量及有效态Cd、Cu、Pb、Zn的含量,但对下层土壤重金属含量影响不明显,并影响其在滩涂土壤中的存在形态,主要表现为：酸溶态比例的提高及残渣态比例的降低。(3)施用生活污泥显著增加了室内模拟土柱条件下的土壤渗漏液Cd、Cu、Pb、Zn浓度。相关性分析表明,渗漏液重金属浓度与DOC呈显著正相关关系,与pH呈显著负相关关系。(4)本试验条件下,生活污泥可安全的用作滩涂土壤改良的有机肥源。各处理土壤所测重金属含量均低于我国土壤质量二级标准的规定值,污泥处理的黑麦草、田菁、玉米植株体内重金属含量均未超出中国饲料质量的国家标准,室内模拟土柱渗滤液重金属含量亦未超出地下水质量Ⅳ类标准。(5)综合考虑改土效果及重金属污染风险,适宜的污泥施用量为：150t ha-1。
[Abstract]:The beach in the eastern coast of China is an important reserve cultivated land resource. However, the newly reclaimed beach is not agricultural cultivated land, so a large number of organic materials must be invested for ripening and improvement. The organic matter and nutrient content of municipal domestic sludge in accordance with agricultural standards in China is high and sticky, which can be used as a cheap and high quality organic fertilizer source for beach soil improvement. However, it has not been reported whether the application of domestic sludge will increase the accumulation of heavy metals in beach soil and whether it will affect the activity of heavy metals in soil, thus increasing the risk of heavy metal accumulation and heavy metal pollution by plants. This seriously hinders the implementation of resource utilization and domestic sludge to improve beach soil. In this study, the municipal domestic sludge which met the agricultural standard was used as the material, and the method of combining field experiment, laboratory simulation, chemical analysis and biological detection was used. The accumulation of main heavy metals in plants, the morphological transformation characteristics of main heavy metals in beach soil and the migration characteristics of heavy metals in soil profile were studied in the process of improving beach soil with different application rates of domestic sludge (0, 30, 75150 300 t / ha-1). The accumulation of main heavy metals in plants, the morphological transformation characteristics of main heavy metals in beach soil, and the migration characteristics of heavy metals in soil profile were discussed in detail. The results showed that: (1) the application of domestic sludge significantly promoted the growth of green manure plants (ryegrass, cyanine, corn seedlings) planted in beach soil, and increased the accumulation of heavy metals (Cd,Cu,Pb,Zn). The main reason for the accumulation was the increase of heavy metal content in the plant. (2) the application of domestic sludge significantly increased the content of total and available Cd,Cu,Pb,Zn in beach soil, but had no obvious effect on the content of heavy metal in the lower soil. It also affects its existing form in beach soil, mainly as follows: the increase of acid soluble state ratio and the decrease of residual state ratio. (3) the application of domestic sludge significantly increased the soil leakage Cd,Cu,Pb, under the condition of simulated soil column in laboratory. Zn concentration. The correlation analysis showed that the concentration of heavy metals in leakage was positively correlated with DOC and negatively correlated with pH. (4) under the experimental conditions, domestic sludge could be safely used as an organic fertilizer source for beach soil improvement. The contents of heavy metals in each treated soil were lower than those in the second class standard of soil quality in China, and the contents of heavy metals in ryegrass, field cyanine and corn plants treated with sludge did not exceed the national standard of feed quality in China. The heavy metal content of simulated soil column leachate does not exceed the class IV standard of groundwater quality. (5) considering the effect of soil modification and the risk of heavy metal pollution, the suitable amount of sludge is 150t ha-1..
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X799.3;S141.6;X53

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