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81.
82.
三江平原湿地土壤活性有机碳组分特征及其与土壤酶活性的关系 总被引:17,自引:2,他引:17
对三江平原3种主要类型天然湿地(毛苔草湿地、小叶章湿地、岛状林湿地)O-20cm土壤活性有机碳(土壤微生物量碳、土壤可溶性有机碳)特征进行了研究,分析了不同湿地的土壤活性有机碳与土壤总有机碳及酶活性间的关系.结果表明:不同类型湿地的土壤活性有机碳组分含量存在较大的差异,土壤活性有机碳、土壤总有机碳及土壤脲酶、蔗糖酶、淀粉酶、过氧化氢酶的变化趋势具有基本近似的特征.表现为毛苔草湿地>小叶章湿地>岛状林湿地;土壤微生物量碳、可溶性有机碳与土壤总有机碳和酶活性存在显著正相关关系,其中,酶活性与土壤微生物量碳相关性最为显著.另外.毛苔草湿地土壤MBC/SOC、DOC/SOC的比值低于其它2种类型湿地,表明毛苔草湿地生物活性有机碳库的周转速率低.淹水抑制了微生物和酶的分解作用,有利于土壤有机碳的累积.因此,沼泽湿地水文条件的变化将会对土壤碳累积与分解过程产生较大的影响. 相似文献
83.
Zhang Xuelin Ren Shufen Li Wencheng Wang Wensheng Wang Jin Wang Wenjun Zhang Yuxia 《环境科学学报(英文版)》1991,3(4):102-107
The relationship between humic acid and selenium content was studied in this research. The results of calculation showed that there is more humic acid and less selenium in Kaschin-Beck disease areas in China. Fulvic acid in soil could increase selenium level in plants. The chemical bonding between humic acid and selenium was observed with an I.R. spectroscope. It was remarkable for the changes of absorption peak and frequency in 1100-1000 cm-1, 900-700 cm-1. 相似文献
84.
氮输入对沼泽湿地小叶章枯落物分解过程中酶活性的影响 总被引:2,自引:1,他引:1
以三江平原沼泽湿地典型湿地植物小叶章枯落物(Calamagrostis angustifolia)为研究对象,采用分解袋法研究了不同外源氮输入(N1、N2分别为6、12g·m-·2a-1)对小叶章枯落物分解过程酶活性的影响,并设置对照区(N0,0g·m-·2a-1)进行比较.研究结果表明,在枯落物最初分解的2个月里,氮输入会抑制蔗糖酶活性,尤其是低氮输入(N1)抑制作用显著(p<0.05),2个月后,氮输入显著促进了该酶活性(p<0.05);;氮输入除在160d时抑制了淀粉酶活性,其它时期均促进了该酶活性,且高氮输入(N2)促进作用显著;;氮输入提高了枯落物分解前2个月的脲酶活性,而在分解后期,低氮输入抑制脲酶活性,高氮输入则主要表现为促进脲酶活性;;低氮输入提高了小叶章枯落物分解前2个月的酸性磷酸酶活性,随后表现为抑制,高氮输入则只在分解后期(160d)抑制酸性磷酸酶活性,其它时期均表现为促进.总体而言,氮输入促进了蔗糖酶、淀粉酶活性,而对于脲酶及酸性磷酸酶活性来说,低氮输入抑制了酶活性,而高氮输入则表现为促进酶活性. 相似文献
85.
The effects of groundwater depth on water uptake of Populus euphratica and Tamarix ramosissima in the hyperarid region of Northwestern China 总被引:2,自引:0,他引:2
Chen Yapeng Chen Yaning Xu Changchun Li Weihong 《Environmental science and pollution research international》2016,23(17):17404-17412
Environmental Science and Pollution Research - Knowledge of the water sources used by desert trees and shrubs is critical for understanding how they function and respond to groundwater decline and... 相似文献
86.
Effect of land-use change on CH4 and N2O emissions from freshwater marsh in Northeast China 总被引:1,自引:0,他引:1
Changsheng Jiang Yuesi Wang Qingju Hao Changchun Song 《Atmospheric environment (Oxford, England : 1994)》2009,43(21):3305-3309
The wetlands play an important role in global carbon and nitrogen storage, and they are also natural sources of greenhouse gases such as methane (CH4) and nitrous oxide (N2O). Land-use change is an important factor affecting the exchange of greenhouse gases between wetlands and the atmosphere. However, few studies have investigated the effect of land-use change on CH4 and N2O emissions from freshwater marsh in China. Therefore, a field study was carried out over a year to investigate the seasonal changes of the emissions of CH4 and N2O at three sites (Deyeuxia angustifolia marsh, dryland and rice field) in the Sanjiang Plain of Northeast China. Marsh was the source of CH4 showing a distinct temporal variation. Maximum fluxes occurred in June and the highest value was 20.69 ± 2.57 mg CH4 m?2 h?1. The seasonal change of N2O fluxes from marsh was not obvious, consisted of a series of emission pulses. The marsh acted as a N2O sink during winter, while became a N2O source in the growing season. The results showed that gas exchange between soil/snow and the atmosphere in the winter season contributed greatly to the annual budgets. The winter season CH4 flux was about 3.24% of the annual flux and the winter uptake of N2O accounted for 13.70% of the growing-season emission. Conversion marsh to dryland resulted in a shift from a strong CH4 source to a weak sink (from 199.12 ± 39.04 to ?1.37 ± 0.68 kg CH4 ha?1 yr?1), while increased N2O emissions somewhat (from 4.07 ± 1.72 to 4.90 ± 1.52 kg N2O ha?1 yr?1). Conversion marsh to rice field significantly decreased CH4 emission from 199.12 ± 39.04 to 94.82 ± 9.86 kg CH4 ha?1 yr?1 and N2O emission from 4.07 ± 1.72 to 2.09 ± 0.79 kg N2O ha?1 yr?1. 相似文献
87.
Changchun Xu Yaning Chen Yapeng Chen Ruifeng Zhao Hui Ding 《Environmental management》2013,51(4):926-938
Based on hydrological and climatic data and land use/cover change data covering the period from 1957 to 2009, this paper investigates the hydrological responses to climate change and to human activities in the arid Tarim River basin (TRB). The results show that the surface runoff of three headstreams (Aksu River, Yarkant River and Hotan River) of the Tarim River exhibited a significant increasing trend since 1960s and entered an even higher-runoff stage in 1994. In the contrary, the surface runoff of Tarim mainstream displayed a persistent decreasing trend since 1960s. The increasing trend of surface runoff in the headstreams can be attributed to the combined effects of both temperature and precipitation changes during the past five decades. But, the decreasing trend of surface runoff in the mainstream and the observed alterations of the temporal and spatial distribution patterns were mainly due to the adverse impacts of human activities. Specifically, increasingly intensified water consumption for irrigation and the associated massive constructions of water conservancy projects were responsible for the decreasing trend of runoff in the mainstream. And, the decreasing trend has been severely jeopardizing the ecological security in the lower reaches. It is now unequivocally clear that water-use conflicts among different sectors and water-use competitions between upper and lower reaches are approaching to dangerous levels in TRB that is thus crying for implementing an integrated river basin management scheme. 相似文献
88.
Chao Liu Hancheng Dai Lin Zhang Changchun Feng 《Frontiers of Environmental Science & Engineering》2019,13(5):70
89.
岩体边坡地震稳定性动安全系数分析方法 总被引:20,自引:0,他引:20
在分析几位学者研究成果的基础上,提出一种适合于岩体边坡动安全系数非线性分析的方法,其主要步骤如下:1)确定介质非线性本构模型的参数;2)考虑边坡的外部及自身载荷,进行边坡静力有限元非线性分析,确定滑坡带单元的初始应力;3)在静力分析的基础上,进行边坡动力有限元非线性分析,确定滑坡带单元的动应力时程;4)根据滑坡带单元的初始静应力和动应力时程,计算每一时刻的边坡动安全系数,从而得到边坡的动安全系数时程;5)根据评价标准,进行边坡地震稳定性评价。 根据上述步骤,结合三峡重庆库区某典型滑坡进行了动安全系数分析,结果表明了该方法可行性。本文只是提出一种初步的边坡稳定性评价标准,由于这方面的震害资料尚少,对其可行性的研究还有待于进一步深入。 相似文献
90.
为揭示昆明松华坝水库人类活动对PAHs(多环芳烃)的影响程度及其污染历史,研究了松华坝水库2根沉积柱(包括集水区人口较密集的1号柱和以山地为主的2号柱)中16种PAHs的垂直分布特征及其来源.结果表明:1号、2号柱中∑16PAHs(16种PAHs总量)分布范围分别为155.9~471.3和100.7~316.3 ng/g,但1号柱污染程度高于2号柱,可能与其集水区较高的人为排放有关.1号柱中∑16PAHs整体随采样深度的下降而降低,2号柱则随采样深度的下降而增长;这2根柱子PAHs的组成相似,沉积物中PAHs均以2环的Nap(萘)和3环的Phe(菲)为主(二者占比高于50%),高致癌性的4~6环PAHs也有较大占比.分子比值法和正定矩阵因子分解法结果显示,1号柱中PAHs主要来源顺序为生物质燃烧源(38.8%)>石油源(34.7%)>煤炭燃烧源(13.4%)>石化燃料燃烧源(13.1%),2号柱主要来源为石油源(44.4%)>生物质燃烧源(26.2%)>煤炭燃烧源(15.3%)>石化燃料燃烧源(14.1%),反映了集水区人类活动方式与强度对沉积物中PAHs的控制作用. 相似文献