采煤塌陷地土壤氮素矿化过程研究

发布时间：2018-08-12 10:48

【摘要】：采煤塌陷湿地是由于人为采煤活动而形成的湿地,陆生环境在短时间内转变为水生环境,转变后微生物群落结构、动植物组成及其氧化还原条件均发生变化,进而影响土壤中元素迁移转化过程。本文分析了潘北采煤塌陷湿地水体和土壤中氮元素分布规律和溶解性有机质(DOM)三维荧光特性,研究了淹水培养、好气培养、去除DOM培养和不同p H值条件下塌陷地土壤氮素矿化过程,并检测了淹水培养和好气培养过程不同阶段的细菌数量和种类。通过上述研究,得到以下结论:(1)采煤塌陷水体总氮、硝酸盐氮和氨氮空间分布较为均匀;各形态氮元素含量呈明显的季节性变化。表层土壤中总氮、铵态氮和硝态氮空间差异性较大;季节性积水区土壤中氮素含量随时间减少,而非季节性性积水区土壤中氮素含量随时间没有明显变化规律。(2)水体DOM分布较为均匀;水体DOM主要组成是类富里酸和类蛋白质,表明塌陷水体形成时间较短,污染少。土壤DOM分布不均匀,随着离塌陷水体边缘距离的增加,土壤DOM含量增加;塌陷区土壤DOM主要组成成分为类富里酸,部分土壤含有类蛋白质,均未检测到含有类腐殖酸。(3)在连续淹水的氮素矿化培养实验中,土壤矿质氮含量前期随时间呈波动变化,后期趋于稳定;好气连续培养条件下,培养前期土壤矿质氮含量较小,40天后含量提高,且高于培养前期。淹水培养矿化氮量明显高于好气培养,表明土壤淹水过程有利于土壤氮素矿化作用。微生物多样性变化与矿质氮含量变化相符合,淹水前期氨化细菌呈增长趋势,随着矿质氮的积累,氨化细菌逐渐减少,硝化细菌数量逐渐增多,20天时细菌丰度与多样性指数均达到最大值,培养后期,由于土壤氧气含量减少,硝化细菌数量逐渐减小。好气培养过程中,细菌数量呈增长趋势;氨化细菌随着培养时间的进行细菌数量先增加后减少;硝化细菌总体呈增长趋势。淹水培养细菌数量大于好气培养,表明淹水培养可以提高土壤细菌活性,促进矿化过程的进行。(4)去除DOM条件下,矿质氮含量前期呈波动变化,后期趋于稳定,但矿质氮含量小于连续淹水条件下的矿质氮含量,尤其在培养初期表现更为明显,表明DOM在土壤有机氮的矿化过程中起着较为重要的作用;(5)p H=4、p H=7、p H=10时,矿质氮随时间变化规律相似,均表现波动下降趋势。p H=7时矿质氮含量高于p H=4、p H=10时,这说明中性条件下适宜氨化微生物的生存。采煤塌陷地土壤p H为6.6-6.8,有利于矿化作用的进行。
[Abstract]:Coal mining collapse wetland is a wetland formed by artificial coal mining. The terrestrial environment is transformed into aquatic environment in a short time. The microbial community structure, animal and plant composition and redox conditions are all changed after the transformation. Furthermore, the process of element migration and transformation in soil was affected. In this paper, the distribution of nitrogen elements in water and soil of Panbei coal mining collapse wetland and the three-dimensional fluorescence characteristics of dissolved organic matter (DOM) were analyzed, and the submergence culture and aerobic culture were studied. Removal of DOM culture and nitrogen mineralization process of subsided soil under different pH values were carried out, and the number and species of bacteria in different stages of submerged culture and aerobic culture were detected. The conclusions are as follows: (1) the spatial distribution of total nitrogen, nitrate nitrogen and ammonia nitrogen in the water body of coal mining collapse is more uniform, and the contents of nitrogen elements in each form show obvious seasonal changes. The spatial difference of total nitrogen, ammonium nitrogen and nitrate nitrogen in the surface soil is great, and the nitrogen content in the soil decreases with time in the seasonal hydrological area. However, there was no obvious change of soil nitrogen content with time in non-seasonal hydrops. (2) the distribution of DOM in water was more uniform, and the main composition of DOM in water was fulvic acid and protein-like, which indicated that the formation time of collapsing water was shorter and the pollution was less. The distribution of soil DOM was uneven, and the content of soil DOM increased with the increase of the distance from the edge of the collapsed water body, and the main component of soil DOM in the subsidence area was fulvic acid, and some of the soils contained protein-like proteins. No humic acid was detected. (3) in the experiment of nitrogen mineralization in continuous flooding, the soil mineral nitrogen content fluctuated with time and tended to be stable in the later stage. The content of mineral nitrogen in soil increased after 40 days, and was higher than that in the early stage of culture. The amount of mineralized nitrogen in flooded culture was significantly higher than that in aerobic culture, which indicated that the process of soil flooding was beneficial to the mineralization of soil nitrogen. The variation of microbial diversity coincided with the change of mineral nitrogen content. The ammoniation bacteria showed an increasing trend in the early stage of flooding, and with the accumulation of mineral nitrogen, the ammoniated bacteria gradually decreased. The abundance and diversity index of nitrifying bacteria reached the maximum after 20 days, and the number of nitrifying bacteria decreased gradually because of the decrease of soil oxygen content in the later stage of culture. During aerobic culture, the number of bacteria increased; the number of ammoniated bacteria increased first and then decreased with the time of culture; the total number of nitrifying bacteria increased. The number of bacteria in submerged culture was larger than that in aerobic culture, which indicated that flooding culture could improve the activity of soil bacteria and promote the process of mineralization. (4) under the condition of removing DOM, the contents of mineral nitrogen fluctuated in the early stage and tended to be stable in the later stage. But the content of mineral nitrogen was lower than that of continuous flooding, especially in the early stage of culture, which indicated that DOM played an important role in the mineralization of soil organic nitrogen. The variation of mineral nitrogen with time was similar, showing a decreasing trend of fluctuation. The content of mineral nitrogen of 7 was higher than that of pH 4 p H = 10:00, which indicated that it was suitable for the survival of ammoniated microorganisms under neutral conditions. The soil pH of coal mining subsidence is 6.6-6.8, which is favorable for mineralization.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S151.9

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