《face条件下稻田ph3释放规律及产生机制》由会员分享，可在线阅读，更多相关《face条件下稻田ph3释放规律及产生机制（92页珍藏版）》请在金锄头文库上搜索。
1、南京师范大学 硕士学位论文 FACE条件下稻田PH3释放规律及产生机制 姓名：张蕤 申请学位级别：硕士 专业：化学；物理化学 指导教师：杨小弟 2009-05-24 摘 要 I 摘 要 摘 要 磷化氢(PH3)是磷循环的气相载体，已被证实是大气中普遍存在的痕量气体(pg ng 级)。环境中 PH3主要来源于湿地、土壤、垃圾填埋场、污水处理厂等厌氧生态环 境。我国大面积的稻田(人工湿地)是环境中 PH3的主要产生场所，但有关稻田 PH3的 释放规律及其产生机制研究报道甚少。 由于人类活动的影响， 大气中 CO2浓度逐年升高。 大气 CO2浓度升高条件下 CH4、 N2O 等痕量气体的释放规律已成
2、为研究热点，PH3作为一种潜在的温室气体，其在 CO2浓度升高条件下的释放规律尚未开展起来。FACE(free air carbon dioxide enrichment)系统是一个模拟未来大气 CO2浓度升高的微域生态环境。本文依托江都 FACE 平台，采用野外实验与室内模拟相结合的方法，运用改进的柱前二次冷阱富集 和气相色谱-氮磷检测器(GC-NPD)联用技术等分析手段， 系统研究了大气 CO2浓度升 高条件下，稻田游离 PH3气体和土壤吸附态 PH3释放规律及其与土壤磷形态的相关 性，研究结果为未来大气 CO2浓度升高条件下，稻田磷的迁移转化及其环境行为有 一定的贡献， 通过室内钢铁腐蚀
3、实验初步探讨了环境中 PH3的产生机制。 主要研究结 果如下： 1. 采用静态箱法测定了水稻不同生长期 FACE 条件和正常大气条件下稻田游离 PH3的释放通量及浓度变化，以及稻田 PH3浓度和释放通量日变化，探讨了大气 CO2 浓度升高及不同氮肥处理水平下稻田 PH3的释放规律。 常氮(250 kg/hm2)条件下， 除扬花期及成熟期外， FACE 圈 PH3释放通量显著大于 对照圈，低氮(125 kg/hm2)条件下，FACE 与对照圈 PH3释放通量差异不显著；不同氮 肥处理对 PH3的释放没有显著影响；水稻生长旺盛期，PH3净通量和稻田上方 PH3的 浓度均较高，而在水稻成熟季，PH3
4、的浓度和通量则较低；水稻田 PH3净释放通量及 浓度与温度均呈显著正相关；稻田水分管理是土壤 PH3释放的另一个影响因子。 对成熟期稻田白天 PH3浓度的测试表明，PH3净通量最大值出现在中午，释放与 吸收同时存在， 温度是稻田 PH3的日释放通量的影响因子； 光照是影响稻田上方大气 中 PH3浓度的主要因素，PH3浓度中午最低，上午最高。 2. 采集水稻 7 个不同生长期的土壤样品，分别测定了吸附态 PH3(MBP)的浓度 及总磷、无机磷、有机磷及有机质含量，并分析了其相关性。对大气 CO2浓度升高 条件下，稻田 PH3的源和汇进行了初步探讨。 水稻移栽期和成熟期土壤中MBP含量显著高于水稻
5、其他生长旺盛期；大气CO2 摘 要 II 浓度升高及不同氮肥水平对稻田MBP含量无显著影响，土壤不同分层之间MBP均无 显著差异；稻田上方PH3浓度与土壤中吸附态PH3浓度显著负相关，稻田上空PH3可能 是由土壤吸附态PH3转化而来的。不同深度土壤中总磷(TP)、无机磷(IP)、有机磷(OP) 及有机质含量均呈下降趋势，除了OP外，其他不同分层均有显著差异；大气CO2浓度 升高条件下，稻田IP显著低于对照，有机质含量显著高于对照；氮肥处理对土壤磷形 态及有机质无显著影响。 土壤吸附态 PH3含量(x)与其相应有机质、IP 含量(y)显著正相关，其相关方程为： y=ax+b，R2 0.16(n
6、= 84)，与 TP、OP 相关性不显著，表明在稻田湿地 IP 最有可能 为 PH3形成的前体物，而有机质在 PH3的形成过程中有重要作用；FACE 条件下，常 氮区 MBP 含量与 TP、IP、有机质的相关性高于低氮区。 3. 采用连续提取法对水稻拔节期及乳熟期 FACE 圈及对照圈稻田土壤的各种形 态磷及部分总金属含量进行了检测，并分析了金属含量与土壤 MBP 含量的相关性， 详细探讨了各种磷形态、不同金属对土壤 MBP 的影响。 土壤中磷主要以钙磷为主，铝磷含量最少，闭蓄态磷含量差异最大；除闭蓄态磷 外，大气 CO2浓度升高对磷形态没有显著影响；CO2浓度升高对稻田土壤中 Fe 和 Ca
7、 含量产生显著影响，而不同氮肥处理对土壤金属含量影响较小。 吸附态 PH3和钙磷、溶解态磷、可交换溶解磷呈显著正相关性，与闭蓄态磷呈显 著负相关，与铁磷、铝磷无显著相关性；土壤吸附态 PH3含量与土壤 Ca 含量显著线 性正相关，与其它几种金属元素无显著线性；大气 CO2浓度升高下，稻田土壤 MBP 含量是多种环境因子共同作用的结果；FACE 条件下，土壤吸附态 PH3与金属的相关 性高于对照。 4. 室内模拟钢铁腐蚀实验结果表明，酸腐蚀铁粉产生 PH3的量比水腐蚀高 3 个 数量级；顶空气体不同，铁粉腐蚀产生 PH3的量不同(空气氮气)；不同质量铁粉腐 蚀后顶空气体中 PH3浓度随铁粉质量增
8、加而增加， 但是腐蚀液中磷酸盐的浓度却没有 规律；在铁粉刚加入时，水腐蚀铁粉产生 PH3的量最大。 关键词关键词：磷化氢(PH3)，稻田，释放通量，季节变化，磷形态，相关性，钢铁，腐蚀 Abstract III Abstract Phosphine is the gaseous carrier in phosphorus cycle, and has been proved to be trace gas (pg/m3 ng/m3) existing generally in atmosphere. Phosphine arises from primarily by anaerobic ec
9、ological environments, such as wetland, soil, landfill, sewage treatment plant and so on. Paddy field of large area was the main source of phosphine in China. However, there have been few researches reported on the release and production mechanism of phosphine in paddy field. Because of human activi
10、ties, carbon dioxide concentration is increased in atmosphere year by year. The release of trace gas such as methane and nitrous oxide under the condition of rising carbon dioxide concentration has attracted much attention. However, there are few studies on phosphine, as a potential greenhouse gas.
11、Free air carbon dioxide enrichment (FACE) system is a micro-domain ecologi cal system simulating carbon dioxide concentration rising in future atmosphere. Based on FACE system in Jiangdu, the release pattern of free phosphine and matrix-bounded phosphine in paddy field, as well as the correlation be
12、tween phosphine and species of soil phosphorus, was systematically studied by an improved GC/NPD method coupled with cryo-trapping enrichment technology with field experiments and indoor simulation. Results showed that rising carbon dioxide concentration in future atmosphere had contribution to tran
13、sportation, transformation and environmental behavior of phosphine in paddy field. Besides, the natural phosphine production mechanism according to indoor steel erosion experiments has been discussed. Results were shown as below: 1. Using static chamber method, we determined variation of fluxes and
14、concentration of free phosphine in paddy field in different growth stage of paddy and a whole day, under FACE condition and normal atmosphere condition, discussed phosphine release in paddy field under FACE and different usage of nitrogen fertilizer. Under normal nitrogen condition (250 kg/hm2), exc
15、ept flowering stage and mature stage, phosphine fluxes in FACE was significantly higher than that in the controlled environment; under low nitrogen condition (125 kg/hm2), there was no obvious difference in phosphine between FACE and the controlled environment. Different level of nitrogen fertilizer
16、 treatment show no significant influence on phosphine release. Net phosphine flux and free phosphine above paddy field were both high in fast-growing period of paddy, and Abstract IV low in mature period. There was significant positive correlation between net phosphine fluxes, phosphine concentration in paddy field and temperature. Another factor that has been identified was water management in paddy field. Determination of
