水稻土硝化/反硝化作用及其功能微生物 对水分条件变化的响应
文献类型：学位论文
| 作者 | 刘若萱 |
| 学位类别 | 硕士 |
| 答辩日期 | 2014-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 贺纪正,张丽梅 |
| 关键词 | 水稻土 水分 氧化还原电位 硝化/反硝化作用 硝化/反硝化微生物 paddy soil moisture redox potential nitrification/denitrification nitrifier/denitrifier |
| 其他题名 | The response of nitrification/denitrification and functional microorganisms to soil moisture change in paddy soils |
| 学位专业 | 环境工程 |
| 中文摘要 | 本研究以江苏滨海、湖南桃源和广东雷州三种不同类型的水稻土为研究对象，在室内微宇宙培养条件下，考察了不同水分条件（30%WHC、60%WHC、90%WHC和淹水2 cm深）处理对土壤硝化/反硝化作用的影响以及硝化/反硝化微生物对水分条件变化的响应。具体结果如下： 滨海水稻土中，淹水处理显著降低了土壤的氧化还原电位Eh，但所有处理土壤Eh变化范围为300～500 mV，土壤整体处于氧化态。在每7天向土壤加入10 mg kg-1NH4+-N的连续培养过程中，各个水分处理均观察到明显的NH4+-N降低和NO3--N累积的现象，60%WHC处理下土壤硝态氮累积最显著和迅速，90%WHC处理次之，随培养时间延长，30%WHC和淹水处理也观察到明显的硝化作用。淹水处理中氨氧化细菌（AOB）的数量显著高于非淹水处理，DGGE结合测序分析结果显示淹水处理后AOB的群落组成发生明显变化，而氨氧化古菌（AOA）的群落组成和数量在不同水分处理间无明显变化。淹水处理后AOB的一些类群如Cluster3a.2和Cluster3b消失，而Cluster3a.1和Cluster7占主导，说明这些类群对水分变化响应灵敏，在该水稻土的硝化作用中起了主导作用。滨海水稻土在培养过程虽然检测不到明显的N2桃源水稻土在整个培养过程中，30%WHC处理土壤无明显的硝化和反硝化作用发生，硝化作用主要发生于60%WHC和90%WHC处理土壤，90%WHC处理土壤硝化作用明显强于60%WHC，并检测到明显的N2O释放，表明该水分条件可能发生了硝化－反硝化耦合作用；淹水处理土壤Eh显著低于非淹水处理土壤，无明显的硝化作用发生，但检测到N2O释放且其释放量小于90%WHC处理土壤。在各水分处理条件下，反硝化功能基因nirS的丰度显著高于nirK基因，但nirK基因对水分变化的响应更灵敏。除培养初期（7天）外，反硝化功能基因nirS和nirK基因，以及氨氧化细菌（AOB）amoA的丰度表现出同样的趋势，均随着水分增加而增加，在90%WHC这一处理土壤中基因丰度最高，在淹水处理的土壤中又有所下降，三者之间呈极显著的正相关关系。AOB的克隆文库结果显示培养过程中桃源土壤中氨氧化细菌类群为Cluster11/12，且无明显变化。运用T-RFLP方法对nirS基因为代表的反硝化微生物群落组成进行的分析表明反硝化微生物对水分条件变化响应灵敏，这些变化的微生物类群可能在不同水分处理土壤的反硝化过程中起主要作用。O释放，但能检测到高丰度的反硝化基因nirS和nirK，且二者的丰度均表现出随水分增加而增加的变化趋势，且其群落结构对不同水分处理产生了一定响应。 雷州水稻土在7天到60天的培养过程中，30%WHC处理无明显的硝化作用和矿化作用发生，加入的NH4+-N显著积累；60%WHC和90%WHC处理土壤硝化作用活跃，Eh在402～613 mV之间，为其硝化作用的发生提供了良好的氧化条件；培养过程中淹水处理土壤虽无明显的硝态氮累积，但有明显的铵态氮消耗和N2O气体释放，表明该土壤中可能发生了活跃的硝化作用，且硝化作用产生的硝态氮随即被还原，硝化和反硝化作用同时发生，该处理土壤Eh最低，有利于反硝化作用的发生。氨氧化细菌AOB群落结构组成随水分梯度增加和培养时间延长发生了明显变化，且淹水处理显著增加了AOB的丰度，而AOA的群落结构组成无明显变化。与非淹水处理相比，淹水培养60天后，AOB的Cluster3a.2明显减少，而Cluster3a.1、Cluster11/12和Cluster Nitrosomonas-like明显增多，表明这些AOB类群在雷州水稻土硝化作用中发挥着主导作用，且对水分条件变化响应显著。对反硝化微生物功能基因的分析结果显示，T-RFLP分析显示以nirS基因为代表的反硝化细菌丰度无明显变化趋势，但群落组成随土壤水分和培养时间增加也发生了轻微变化。 |
| 英文摘要 | To investigate the response of nitrification and denitrification to different moisture gradients and the underlying microbiological mechanism, three kinds of paddy soils were collected from Binhai (Jiangsu Province), Taoyuan (Hunan Province) and Leizhou (Guangdong Province), soil microcosm experiments were set up with 4 moisture gradients including 30%WHC,60%WHC,90%WHC, and waterlogged in this study.Results were as follows. For Binhai paddy soil, the Eh in waterlogged treatment was significantly lower than other three non-waterlogged treatments, but showed no significant difference among three non-waterlogged treatments. In addition, the Eh in all treatments ranged from 300 to 500 mV, indicating that the paddy soil remained oxidation state basically. During the incubation, 10 mg kg-1 NH4+-N was added into soil at every 7 days. Abrupt decrease in the concentration of NH4+-N was observed in all moisture treatments over time, accompanying the rapid increase in NO3--N concentration, especially in 60%WHC and 90%WHC treatments. Even though the accumulation of NO3--N in 30%WHC and waterlogged treatments were slow, the active nitrification was observed in the later period of incubation. Compared with non-waterlogged treatments, waterlogged treatment significantly increased the abundance of ammonia oxidizing bacteria (AOB).The dominant AOB bands in DGGE profiles were more bright in waterlogged treatment than others, while the abundance and community structure of ammonia oxidizing archaea (AOA) showed no clear change among 4 different moisture treatments. All these indicated that different ammonia oxidizers required different water and oxygen conditions, and some AOB populations were active and responsible for the ongoing nitrification in the tested soil, especially in waterlogged treatment. Some AOB groups such as Cluster3a.2 and Cluster3b disappeared, while others such as Cluster3a.1 and Cluster7 dominated in waterlogged treatment.The abundance of nirS and nirK genes increased with the increasing soil moisture gradients, and nirS gene was significantly more abundant than nirK gene in all treatments. T-RFLP analysis showed that nirS gene-containing denitrifiers community responded slightly to soil moisture change. For Taoyuan paddy soil, no active nitrification and denitrification occurred in 30%WHC treatment as there were no obvious ammonia consumption and nitrate accumulation while nitrification were active in 60%WHC and 90%WHC treatments as indicated by the obvious accumulation of nitrate in both treatments. Meanwhile, significant ammonia consumption and N2O emission over time were observed in 90% WHC treatment, implying that nitrification was much stronger in 90%WHC treatment than in 60%WHC treatment and denitrification occurred coupling with nitrification in 90%WHC treatment. In waterlogged treatment, N2O emission was detected but it was weaker than that in 90%WHC treatment, and no obvious nitrification was detected, corresponding a significant lower soil Eh than in other three non-waterlogged treatments. Except that there was some variation among different moisture treatments at the early stage of incubation (7 days), the abundance of denitrifying genes nirS, nirK and ammonia-oxidizing microorganisms AOB amoA gene showed consistent trend in response to soil moisture change over time. The abundance of the three genes increased significantly with the increasing moisture gradients but decreased slightly in waterlogged treatment, and the highest values were observed in 90%WHC treatment in which the highest nitrification and denitrification activity were observed.Clone library results showed that AOB group was mainly dominated by Cluster11/12 and changed a little during incubation. T-RFLP analysis showed that the community composition of nirS gene-containing denitrifier changed significantly in response to soil moisture change after two weeks, and soil Eh and Cw were the main factors affecting the community composition of denitrifier. For Leizhou paddy soil, nitrification was not observed in 30%WHC treatments but active in 60% and 90%WHC treatments, corresponding the high Eh values in these two treatmens. N2O emission was only detected in waterlogged treatment and accompanied with obvious ammonia consumption, indicating denitrification occurred coupling with nitrification. Correspondingly, Eh in waterlogged treatment was gegerally lower than non-waterlog treatments.Simlar to Binhai soil, AOB amoA gene abundance increased with the increasing moisture levels, and AOB community composition showed significantly change over time and among moisture levels. Comparing with non-waterlogged treatments, some AOB groups such as Cluster3a.2 decreased, while others such as Cluster3a.1, Cluster11/12 and Cluster Nitrosomonas-like increased in waterlogged treatment, indicating that some AOB populations (Cluster3a.1, Cluster11/12 and Cluster Nitrosomonas-like) were responsible for nitrification in Leizhou paddy soil and they responsed greatly to moisture change.While the abundance of AOA amoA gene, nirS and nirK gene showed no clear tread among different moisture treatment. The community composition of nirS gene-containing denitrifier showed slightly change in response to soil moisture levels. |
| 公开日期 | 2015-07-08 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/15723]  |
| 专题 | 生态环境研究中心_土壤环境科学实验室 |
| 推荐引用方式 GB/T 7714 | 刘若萱. 水稻土硝化/反硝化作用及其功能微生物 对水分条件变化的响应[D]. 北京. 中国科学院研究生院. 2014. |
入库方式： OAI收割
来源：生态环境研究中心
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