氮肥对土壤氧化大气甲烷影响的机制

综合评述了氮氧化甲烷的抑制机制。包括：（1）竞争甲烷单氧化酶的竞争抑制机制,（2）代谢产物的毒害抑制机制,（3）外源盐引起的微生物生理缺水抑制机制和（4）氮素周围作用引起的抑制机制。提出了氧化菌竞争利用土壤空气有限O2的竞争抑制机制,即氨氧化菌利用更多的土壤有限氧气→产生优势氨氧化菌→形成优势菌群→限制甲烷氧化菌繁殖和功能发挥的氨长期抑土壤化大气甲烷的机制,并认为这种抑制作用是不可逆的。     

稻田甲烷氧化与铵氧化关系研究进展

稻田生态系统中存在着好氧微域,其中同时发生甲烷氧化和铵氧化。甲烷和铵氧化过程具有极为相似的微生物机理。稻田土壤中的甲烷可能影响铵氧化过程;施用铵态氮肥对甲烷的氧化也有强烈影响。本文对稻田土壤中甲烷氧化与铵氧化关系做一简要综述。     

废水处理新技术中的超临界水氧化法

超临界水氧化法是一种有效处理有机废水的方法,本文在总结超临界水的特点和优点的基础上,着重介绍了超临界水氧化的基本原理,工艺流程及应用状况,探讨该项技术的前景与发展趋势。、     

湿式氧化生物氧化两步法处理有机磷农药生产废水

本文报道了用湿式氧化结合生物氧化两步法,处理有机磷农药生产废水的研究结果.在较缓和条件下,湿式氧化一步可去除有机磷80—90％,有机硫90％,较大幅度降低了废水的COD值.湿式氧化使废水的BOD_5/COD比值从0.2左右上升到0.4—0.5,废水的可生化性显著提高.在遵循常规生化处理必须满足的条件下,湿式氧化处理后的废水进一步用活性污泥传统曝气法处理,COD可再下降90％以上,有机磷得到去除,出水达标.     

苯胺的超监界水氧化研究

苯胺的超临界水氧化表明,氧化剂H2O2、试验温度、压力和停留时间以及水样的起始TOC值对TOC的去除率有显著影响。在本试验中,选取了硫酸铜、硫酸铁、硫酸锰等金属盐进行苯胺的均相催化氧化试验研究,结果表明,这些金属盐对苯胺的氧化有不同的催化活性,筛选出硫酸锰和硫酸亚铁进行了进一步研究,以硫酸猛作催化剂为例,在450℃,28MPa,K＝1．1,pH＝4．0的条件下,当停留时间为46s时,TOC去除率达到100％。     

苯胺的超临界水氧化研究1

苯胺的超临界水氧化表明,氧化剂Ｈ２Ｏ２、试验温度、压力和停留时间以及水样的起始ＴＯＣ值对ＴＯＣ的去除率有显著影响．在本试验中,选取了硫酸铜、硫酸铁、硫酸锰等金属盐进行苯胺的均相催化氧化试验研究,结果表明,这些金属盐对苯胺的氧化有不同的催化活性,筛选出硫酸锰和和硫酸亚铁进行了进一步的研究．以硫酸锰作催化剂为例,在４５０℃,２８ＭＰａ,Ｋ＝１．１,ｐＨ＝４．０的条件下,当停留时间为４６ｓ时,ＴＯＣ去除率达到１００%．     

催化湿式氧化法预处理显影废水的研究

考察了催化湿式氧化法对医院显影废水进行预处理的可行性.紫外扫描结果表明,对甲氨基苯酚硫酸盐、对苯二酚等特征污染物被降解为小分子物质,在催化剂Ru/TiO2存在下,催化湿式氧化法与湿式氧化相比,有机物的降解更加彻底.通过考察催化剂用量、温度、压力及pH值等条件对CODCr去除率的影响,确定适宜的反应条件为:催化剂用量为2g·l-1,温度为220℃,压力为1.5MPa,pH为8.9.在上述反应条件下,CODCr去除率达62.5%,色度去除率达98%,BOD5/CODCr值由原来的0.07提高到0.45.     

氮肥对土壤氧化大气甲烷影响的机制

综合评述了氮素对土壤氧化甲烷的抑制机制。包括 :( 1)竞争甲烷单氧化酶的竞争抑制机制 ,( 2 )代谢产物的毒害抑制机制 ,( 3)外源盐引起的微生物生理缺水抑制机制和 ( 4)氮素周转作用引起的抑制机制。提出了氧化菌竞争利用土壤空气有限O2 的竞争抑制机制 ,即氨氧化菌利用更多的土壤有限氧气→产生优势氨氧化菌→形成优势菌群→限制甲烷氧化菌繁殖和功能发挥的氨长期抑制土壤氧化大气甲烷的机制 ,并认为这种抑制作用是不可逆的     

高浓度有机废水深度氧化治理技术进展

介绍处理废水中生物难降解有机污染物的深度氧化技术———湿式空气氧化法、超临界水氧化法、复合空气氧化法、光化学氧化法及其相应的催化氧化法,评价这些方法的特点及应用前景。     

Quantity and activity of ammonia-oxidizing archaea and bacteria and their contribution to ammonia oxidation in farmland soil of Qinghai-Tibet Plateau北大核心CSCD

Ammonia oxidation, the first and rate-limiting step of nitrification, is mainly performed by ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). However, the activities of AOA and AOB in soil and their relative contribution to ammonia oxidation are unclear, and whether there is a significant correlation between the quantity of AOA and AOB and the ammonia oxidation rate is also controversial. In this study, quantitative PCR combined with acetylene (C2H2) and 1-octyne inhibition methods were used to determine the quantity and activity of AOA and AOB in wheat, highland barley, and oilseed rape soils in Nyingchi, Lhatse, Sangzhuzi, and Sangri counties on the Qinghai-Tibet Plateau. The results showed that the quantity of AOB ((2.34 ± 0.84) ×105 - (2.65 ± 1.07) ×106 copies g-1 dry soil) was significantly higher than that of AOA ((0.20 ± 0.10) ×104 - (4.02 ± 0.39) ×104 copies g-1 dry soil) in all the soil samples. Soil pH was the key factor affecting the quantity of AOB, and the total phosphorus and ammonium nitrogen in soil were the key factors affecting the quantity of AOA. The rates of ammonia oxidation in the farmland soils of Lhatse (2.42 ± 0.73 mg kg-1 d-1) and Sangzhuzi (3.24 ± 1.15 mg kg-1 d-1) were significantly higher than those in the soils of Nyingchi (1.17 ± 0.43 mg kg-1 d-1) and Sangri counties (0.88 ± 0.57 mg kg-1 d-1). The rates of ammonia oxidation in the farmland soils of Lhatse and Sangzhuzi were dominated by AOB, while those in the farmland soils of Nyingchi and Sangri counties were dominated by AOA. For crops, the ammonia oxidation rates of wheat and oilseed rape soils in all four regions were significantly higher than those of highland barley soil, whereas the activity of AOA and AOB was not influenced by crops. The ratio of nitrogen to phosphorus was the key factor influencing AOA activity, whereas soil pH and total carbon were the main factors influencing AOB activity. Additionally, the quantities of AOA and AOB were not significantly correlated with the total ammonia oxidation rates and AOA and AOB activity. Overall, our study suggests that both AOA and AOB play important roles in ammonia oxidation in farmland soils of the Qinghai-Tibet Plateau. Moreover, it is unreliable to predict the activity of AOA and AOB and their relative contribution to ammonia oxidation directly based on their number of amoA genes, and the activity of AOA and AOB should be directly and accurately measured. These results are important for understanding ammonia nitrogen removal processes, slowing nitrate loss, and reducing the emission of the greenhouse gas nitrous oxide in the farmland ecosystem of the Qinghai-Tibet Plateau. © 2022 Science Press. All rights reserved.