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331.
332.
The objective of this study was to investigate the soil nitrogen components of four native artificial plantations at the western edge of the Sichuan Basin. Soil samples from two layers (0-20 cm and 20-40 cm) were collected from 4 plantations (Cryptomeria fortunei, Michelia wilsonii, Phoebe zhennan, and Quercus acutissima) during March, June, September, and December 2015 at the western edge of Sichuan Basin, to perform a comparative analysis on seasonal dynamics. Soil ammonium, nitrate, microbial biomass nitrogen, and environmental factors were synchronously monitored. The results showed that soil inorganic nitrogen was mainly the result of nitrate. The components of labile soil nitrogen showed significant seasonal dynamics. Soil ammonium during the growing season (June and September) was higher than that during the non-growing season (March and December), but soil nitrate, microbial biomass nitrogen, and inorganic nitrogen showed the opposite pattern. Labile nitrogen components in the 0-20 cm layer were generally higher than those in the 20-40 cm layer. Labile soil nitrogen was significantly affected by forest type, which was dependent on season and soil layer. In general, there were significant correlations between the soil nitrogen pools and labile soil nitrogen and the environmental factors, including soil temperature, water content, and monthly rainfall. In conclusion, the variation of labile soil nitrogen was influenced more by season than forest type or soil layer. Compared to the biological effects of tree species, the environmental factors had a stronger effect on labile soil nitrogen. © 2018 Science Press. All rights reserved. 相似文献
333.
本文总结了近年来有毒物质对水生态系统的生态效应研究现状及发展趋势,提出了今后测定有毒物质生态效应应该注意的问题。 相似文献
334.
废轮胎的热解及其产物分析 总被引:16,自引:0,他引:16
研究了废轮胎热解产生的三相 (气、液、固 )产率与裂解温度的关系 ,气相组成与温度的关系 ,以及氢氧化钠作为催化剂加入热解体系对三相产率和气体组成的影响 .实验表明 ,轮胎橡胶的热稳定性分为 :~ 200℃,200℃~300℃及300℃以上3个区域 .在200℃以上时 ,随着温度升高 ,固体产率减少 ,气体产率增加 ,液体产物的产率在 500℃左右出现一个峰值 .加入 4%NaOH作催化剂以后 ,在相同的温度下固态碳黑和液态油的产率均有所提高 ,而相应混合气的产率降低 .实验确定了所用混合胶粉主要为合成橡胶 .不同温度下热解所产生的液体产物的红外谱图及裂解色谱图表明 ,300℃时主要是助剂分解,400℃左右主要是聚异戊二烯(天然胶)开始裂解,600℃以上残留物开始裂解. 相似文献
335.
Yafang Shi Yunchao Dai Ziwen Liu Xiaofeng Nie Song Zhao Chi Zhang Hanzhong Jia 《Frontiers of Environmental Science & Engineering》2020,14(6):106
336.
不同碳源条件下聚磷菌代谢特性 总被引:3,自引:0,他引:3
利用2套SBR系统在厌氧好氧交替条件下对聚磷菌(phosphorus accumulating organisms,PAO)进行富集,分别采用乙酸和丙酸作为碳源。通过对典型周期内磷酸盐,聚羟基烷酸(polyhydroxyalkanoates,PHAs),糖原和多聚磷酸盐变化情况的分析,探讨了不同碳源下,聚磷菌胞内碳源物质的代谢机理以及其对于生物除磷的影响。结果表明,以乙酸为碳源时,PHAs的合成量和分解量都要高于丙酸为碳源,且PHAs主要成分以聚-β-羟丁酸(poly-β-hydroxybutyrate,PHB)为主,污泥的比释磷速率和比吸磷速率都要高于丙酸为碳源的情况。 相似文献
337.
以市售活性炭、硅藻土和氧化铝小球为载体,考察了负载铁基活性组分对催化臭氧化过程中溴酸盐的控制情况,其中,铁基复合氧化铝小球体现出更好的溴酸盐还原特性和催化剂稳定性,证实催化剂中铁氧化物是溴酸盐得到有效控制的主要活性组分。进一步考察了铁基复合氧化铝小球催化臭氧化处理实际原水过程中对溴酸盐的生成控制,以及反应过程中溶解性有机碳(DOC)的去除情况。结果表明,与单独臭氧化相比,该催化剂既能有效去除水中的溶解性有机物,又能明显抑制溴酸盐的生成,反应50 h,其活性并没有明显下降。催化剂失活主要归因于吸附位点数量的下降,可以通过负载铁氧化物来实现催化剂的再生。 相似文献
338.
This study presents a two-stage vertex analysis (TSVA) method for the planning of electric power systems (EPS) under uncertainty. TSVA has advantages in comparison to other optimization techniques. Firstly, TSVA can incorporate greenhouse gas (GHG) abatement policies directly into its optimization process, and, secondly, it can readily integrate inherent system uncertainties expressed as fuzzy sets and probability distributions directly into its modeling formulation and solution procedure. The TSVA method is applied to a case study of planning EPS and it is demonstrated how the TSVA efficiently identify optimal electricity-generation schemes that could help to minimize system cost under different GHG-abatement considerations. Different combinative considerations on the uncertain inputs lead to varied system costs and GHG emissions. Results reveal that the total electricity supply will rise up along with the time period due to the increasing demand and, at the same time, more non-fossil fuels should be used to satisfy the increasing requirement for GHG mitigation. Moreover, uncertainties in connection with complexities in terms of information quality (e.g., capacity, efficiency, and demand) result in changed electricity-generation patterns, GHG-abatement amounts, as well as system costs. Minimax regret (MMR) analysis technique is employed to identify desired alternative that reflects compromises between system cost and system-failure risk. 相似文献
339.
采用粘结剂聚乙烯醇(PVA)、造孔剂碳酸氢钠(NaHCO3)和微波强化Al改性膨润土(以下简称M-Al-Bt)制备改性膨润土颗粒(以下简称MBG),研究MBG对微污染水中有机物和氨氮(NH4-N)的吸附效果,考察了不同投加量、反应时间、pH值对腐殖酸(HA)和NH4-N的去除效果影响.结果表明,投加量3 g/L,反应时间20 min,pH =7时,MBG对微污染水中20 mg/L HA和5mg/L NH4-N的去除率分别可达98%和20%以上.HA和NH4-N共存时,存在竞争吸附,HA影响了MBG对NH4-N的去除. 相似文献