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《亚热带资源与环境学报》2020,(1)
土壤CO_2释放是土壤碳转化的关键过程。氮(N)添加及植物枯落物的分解对湿地土壤CO_2释放速率有显著影响,在全球大气CO_2浓度和气候变化中具有重要作用。本研究选取闽江河口湿地土壤为研究对象,通过24 d的短期培养实验,研究不同氮浓度和不同枯落物添加对闽江河口湿地土壤CO_2释放速率的影响。结果表明:(1)短叶茳芏(Cyperus malaccensis)和互花米草(Spartina alterniflora)两种植物枯落物添加处理显著促进了湿地土壤CO_2释放速率(P0.05),也显著增加了闽江河口湿地土壤溶解性有机碳(DOC)、微生物量碳(MBC)和pH(P0.05)。两种枯落物添加处理下,培养初期(0～9 d)枯落物可溶性有机碳快速释放和pH升高可能是导致土壤CO_2释放峰值时间提前的主要因素。(2)枯落物添加后不同浓度氮输入对湿地土壤CO_2释放速率均具有显著影响(P0.001),但两种枯落物对土壤CO_2释放速率的影响并无显著差异(P0.05)。土壤微生物量碳(MBC)、土壤微生物量氮(MBN)的变化是影响不同枯落物在氮添加后培养前、后期土壤CO_2释放差异的重要原因。 相似文献
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《资源与生态学报(英文版)》2017,(2)
理解土壤可利用性氮(N)如何与土壤酸化和可利用性磷(P)共同作用影响土壤-大气界面CO_2、CH_4和N_2O气体交换,对于揭示生态系统对氮沉降增加的响应机制尤为重要。本研究在中国亚热带地区混交林中设置了N、P和酸添加实验以理清在N添加下酸和P添加如何影响CO_2、CH_4和N_2O气体交换。结果表明,(1)N添加显著增加了土壤铵态氮和硝态氮,对CO_2释放无影响;(2)N、P、N+P和N+P+酸分别降低了21.1%、15.7%、39.1%、26.6%和28.4%的CH_4;相比于N、P单独添加,NP共同添加降低了CH_4吸收,表明N添加和P添加在抑制CH_4吸收上具有加和效应;(3)N、N+P、N+酸和N+P+酸分别增加了158.6%、176.0%、117.2%和91.8%的N_2O释放;N_2O释放在N+P+酸处理中显著低于N+P处理,与N添加和N+酸添加无显著差异,表明在N添加下,仅P丰富的条件下,酸添加才能够缓解N_2O释放。我们的结果证实,在N和P共同限制的酸性土壤森林生态系统,低P将会抑制N沉降引起的土壤CH_4吸收。低P时,N沉降引起的土壤酸化与其引发的N_2O释放无关。 相似文献
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吉林东部山地沼泽湿地土壤碳、氮、磷含量及其生态化学计量学特征 总被引：3，自引：0，他引：3
湿地土壤有机碳、氮和磷含量变化显著影响着湿地生态系统的生产力。为阐明吉林东部山地沼泽湿地土壤养分的空间分布特征,以吉林省敦化市4种典型山地沼泽湿地：落叶松-苔草湿地(T1)、莎草湿地(T2)、小叶章-甜茅湿地(T3)和沼泽化草甸湿地(T4)为研究对象,研究了土壤有机碳、全氮和全磷含量及其化学计量比的空间分布特征及影响因素。结果表明：4种山地沼泽湿地类型土壤有机碳、全氮、全磷含量均值分别为343.11 mg/g、28.03 mg/g和4.00 mg/g,变异系数为有机碳(9.26%)<全氮(16.52%)<全磷(48.64%)。在0~40 cm土层内, T1、T2和T3土壤有机碳、全氮、全磷含量随土壤深度的增加呈先增加后减少的趋势,在10~20 cm土层出现累积峰; T4土壤有机碳、全氮、全磷含量随土壤深度的增加而减少。土壤有机碳、全氮含量的变化趋势为T1相似文献
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外源氮输入对沼泽湿地小叶章枯落物性质及其早期分解的影响 总被引：6，自引：0，他引：6
在三江平原沼泽湿地,选取典型湿地植物小叶章(Calamagrostis angustifolia)为研究对象,对比研究了连续施氮[24g/(m2·a)]3a的小叶章立枯物(N24)与自然条件下形成的立枯物(CK)的差异;并采用分解袋法对此2种小叶章枯落物的早期分解过程进行了研究。结果表明,施氮处理下小叶章立枯物的氮、磷含量均高于CK,但碳含量显著降低(n=3,p<0.05)。施氮处理下形成的小叶章枯落物的分解速率明显大于CK,分解160d后两者的失重率分别为初始值的31.13%(N24)和28.50%(CK)。分解过程中,2种处理下枯落物有机碳的绝对含量都表现为净损失;其氮、磷浓度的变化趋势大致相同,分解160d后均发生了氮、磷的净释放,其中,N24的氮、磷净释放量分别是CK的64.91和2.11倍。外源氮输入影响下小叶章枯落物C/N和C/P值的降低,加快了该枯落物的分解速率,从而影响土壤有机质的累积和CO2的排放;而该枯落物分解过程中营养元素释放量的增大,还可能会影响土壤其它营养元素可利用性。 相似文献
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复合人工湿地对氮的深度处理效果及影响因素 总被引：2，自引：0，他引：2
研究了2008年5~10月对废水中氮的深度处理效果,采用Monod动力学模型对该人工湿地进行模拟并验证,分析进水中NH4+—N和NO3-—N的含量与其去除率的相关性以及COD/NH4+—N、COD/NO3-—N对降解系数的影响。结果表明,①复合湿地组合形式对NH4+—N和NO3-—N的去除率分别介于66.0%~77.1%和46.2%~77.2%之间;②Monod模型对人工湿地中NH4+—N和NO3-—N去除率的预测值与实验观测值吻合程度较好;③NH4+—N和NO3-—N的去除率分别随着其在进水中的含量的增加而增大;④进水中的COD/NH4+—N与KNH4+—N呈负相关关系,而COD/NO3-—N与KNO3-—N呈正相关关系。人工湿地中硝化和反硝化作用受到进水中NH4+—N和NO3-—N含量的限制,氮的去除率随着进水中NH4+—N和NO3-—N浓度的增加而增大。有机物和NH4+—N在人工湿地中的降解可能存在竞争氧的关系,可利用碳源构成了反硝化作用的限制因素。 相似文献
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盐度对河口潮汐湿地温室气体产生和排放的影响研究进展 总被引：2，自引：0，他引：2
盐度是影响河口潮汐湿地温室气体动态的一个重要的环境因子。本文论述了盐度对河口潮汐湿地温室气体的产生和排放的影响及机制。盐水入侵通过带来丰富的SO42-引起的硫酸盐效应、离子强度增加引起的离子效应影响CH4和CO2的产生。盐水入侵通过影响湿地的硝化作用、反硝化作用及硝化细菌反硝化作用进而影响N2O产生量,影响方式主要包括:(1)通过物理化学机制加强沉积物中铵的释放;(2)通过生理机制增加沉积物氮素释放量,直接影响硝化细菌、反硝化细菌活性,进而影响硝化作用和反硝化作用;(3)通过提高硝酸盐异化还原为铵的速率影响反硝化速率。最后提出了今后应加强研究的方向。 相似文献
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湿地生态系统独特的生态特性使其在温室气体的固定和释放中发挥了重要作用,湿地生态系统CO2源/汇成为全球气候变化研究中的热点问题。该文系统总结了近年来湿地生态系统CO2源/汇特征,探讨了自然环境因子以及人类活动对湿地CO2源/汇功能的影响。研究表明,目前绝大多数湿地生态系统是大气CO2的汇,湿地CO2源/汇特征表现出明显的时空变异性。气温是气象因素中影响湿地净生态系统CO2通量(NEE)变化的一个重要甚至首要因子;土壤状况因子包括温度、pH值等均对NEE有明显影响,但影响程度不同;湿地水文对CO2源/汇的影响主要表现在干、湿季以及水位变化对NEE的影响上;植被类型及干扰程度不同,湿地CO2源/汇功能具有很大差异;人类活动尤其是将湿地开垦为农田,会使湿地变成大气CO2的源,而生态修复则使湿地作为大气CO2汇的能力得到恢复。 相似文献
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《The Professional geographer》1988,40(4):471-499
Books reviewed in this article: USA, Eine Geographische Landeskunde , Vol. I, Der Grossraum in Strukturellem, Wandel, 3rd Ed. Helmut Blume . Introduction to Remote Sensing . James B. Campbell . The Sounds of People and Places: Readings in the Geography of American Folk and Popular Music . George O. Carney , ED. Development and Underdevelopment . John Cole . Mobility and Employment in Urban Southeast Asia: Example from Indonesia and the Philippines . Michael A. Costello , Thomas R. Leinbach , AND Richard Ulack . Soviet Asia: Economic Development and National Policy Choices . Leslie Dienes . The Third World City . David Drakakis -Smith . Scholars' Guide to Washington, DC for Cartography and Remote Sensing Imagery (maps, charts, aerial photographs, satellite images, cartographic literature and geographic information systems). Ralph E. Ehrenberg . Population and Development in the Third World . Allan AND Anne Findlay . The Early Mapping of Hawaii . Gary L. Fitzpatrick . Energetics of Physical Environment: Energetic Approaches to Physical Geography . K. J. Gregory , ED. Wildland Recreation: Ecology and Management . William E. Hammitt and David N. Cole . Agricultural Commercialization and Government Policy in Africa . J. Hinderink AND J. J. Sterkenburg . The Dynamics of American Housing . James W. Hughes AND George Sternlieb . Thailand: Buddhist Kingdom as Modern Nation State . Charles F. Keyes . Resolving Locational Conflict . Robert W. Lake , ED. Lands at Risk in the Third World: Local-level Perspectives . Peter D. Little and Michael M. Horowitz , EDS. Nathaniel Southgate Shaler and the Culture of American Science . David N. Livingstone . Regions: The Economics and Politics of Territory . Ann R. Markusen . Wetlands . William J. Mitsch and James G. Gosselink . Historical Geography: Progress and Prospect . Michael Pacione , ED. Loess and Periglacial Phenomena . Marton P$eacsi and Hugh M. French , EDS. Regional Management of Metropolitan Floodplains, Experience in the United States and Abroad . Rutherford H. Platt , ED. Human Cartography: Mapping the World of Man . Janos Szegö . Atlas of Great Lakes Indian History . Helen H. Tanner , ED. The Botany of Mangroves . P. B. Tomlinson . Urban Spatial Traffic Patterns . Rodney Vaughan . The Night After … Climatic and Biological Consequences of a Nuclear War . Yevgeni Velikhov , ED. Industrial Geography . H. D. Watts . Dictionary of Quotations in Geography . James O. Wheeler and Francis M. Sibley . Vermont Townscape . Norman Wiliams , Jr. , Edmund K. Kellogg and Peter M. Lavigne . 相似文献
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P. Guilizzoni A. Marchetto A. Lami N. G. Cameron P. G. Appleby N. L. Rose Ø. A. Schnell C. A. Belis A. Giorgis L. Guzzi 《Journal of Paleolimnology》1996,15(3):245-264
A palaeoecological study of an oligotrophic alpine lake, Paione Superiore (Italy), provided a record of historical changes in water quality. Historical trends in lake acidification were reconstructed by means of calibration and regression equations from diatoms, chrysophycean scales and pigment ratios. The historical pH was inferred by using two different diatom calibration data sets, one specific to the alpine region. These pH trends, together with the record of sedimentary carbonaceous particles and chironomid remains, indicate a recent acidification of this low alkalinity lake.Concentration of total organic matter, organic carbon, nitrogen, biogenic silica (BSiO2), chlorophyll derivatives (CD), fucoxanthin, diatom cell concentration and number of chironomid head capsules increased during the last 2–3 decades. When expressed as accumulation rates, most of these parameters tended to decrease from the past century to c. 1950, then all except P increased to the present day. A marked increase in sedimentary nitrogen may be related to atmospheric pollution and to the general increases in output of N in Europe. High C/N ratios indicate a prevailing allochthonous source of organic matter.Finally, the increase in measured air temperature from the mid-1800's appeared to be related to lake water pH before industrialization: cold periods generally led to lower pH and vice-versa. The more recent phenomenon of anthropogenic acidification has apparently decoupled this climatic-water chemistry relationship. 相似文献
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K. F. Walker I. G. Dunn D. Edwards T. Petr H. Z. Yang 《International Journal of Salt Lake Research》1995,4(3):169-222
Quinghai Hu is a large, high-altitude, saline lake in north-western China, and supports a fishery based on an endemic species of naked carp (snow trout). The fish take seven years to attain maturity and a marketable weight of 300 g, and have a lifespan of 14–21 years under the present fishery regime. They seasonally migrate from the lake to spawn over the gravel beds of inflowing rivers, but these areas have been reduced by weirs and irrigation diversions and recruitment may have declined. The population may have been affected also by a 1.85-m fall in the lake level over the past 30 years, and by associated changes in salinity. The fishery was opened to large-scale exploitation in 1958. Yields declined sharply (max. 28,523 tonnes, 1960) as the larger, older fish were removed, and then more slowly (min. 2523 tonnes, 1983). Since 1987 the fish factory has been limited to an annual quota of 1200 tonnes, taken by a fleet of four pair trawlers. Another 800 tonnes are taken by licensed fishermen, mainly using gill nets, and perhaps 1000 tonnes are taken illegally. The estimated total catch in 1992 was 3000 tonnes. New trawlers introduced in 1989–90 substantially increased the factory's catch per unit effort, and in 1990 the quota was virtually filled in one month in a zone within 20 km of the factory. Although this could suggest that the stocks will be conserved if the quota is retained, at least half of the catch in 1989–92 consisted of immature individuals. Trawling operations recently were suspended following a further decline in the catch after 1992. While the new trawlers are capable of a major increase in effort, neither the changing environment, the fish stocks or the present markets favour intensified pressure. Gillnets may provide better control over the minimum size limit and may cause less damage than trawling. Other options to improve the viability and profitability of the fishery include improvements in handling, processing and marketing. Failure to develop the fishery may encourage attempts to introduce exotic fish, at some risk to survival of the local species. 相似文献
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Chironomidae (Diptera) remains in surficial lake sediments from the Canadian Cordillera: analysis of the fauna across an altitudinal gradient 总被引：3，自引：0，他引：3
The altitudinal distribution of Chironomidae (Diptera) in the southern Canadian Cordillera was analyzed by means of head capsules preserved in surficial sediments of 30 lakes. Taxa characteristic of late-glacial deposits of southern, coastal British Columbia are extant at high elevations, particularly in the Rocky Mountains, and in large, deep, low-elevation lakes. Many chironomid taxa common at low elevations in the southern Canadian Cordillera were not found in alpine and upper subalpine lakes. These faunal differences are probably climatically related. The differences in fauna between high and low-elevation lakes parallel differences between arctic and temperate lakes. 相似文献
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MATT K. MATSUDA 《Geographical review》2007,97(2):230-243
ABSTRACT. Narratives concerning Pacific Ocean territories are often historically derived from European and American mainland visions of great, empty oceans dotted with deserted and uninhabited islands. However, research by indigenous and outlander scholars, along with struggles for political and cultural autonomy in the Pacific, has brought attention to vital island communities and 6has raised questions about a Pacific‐island way of understanding the world. This understanding is traced through scholarly and artistic engagements with history, island‐community studies, and navigational philosophies and is framed by a growing theoretical literature on epistemologies of place from the disciplines of geography and oceanography. 相似文献
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Precipitation is an important component of global water and energy transport and a major aspect of climate change. Due to the scarcity of meteorological observations, the precipitation climate over Tibet has been insufficiently documented. In this study, the distribution of precipitation during the rainy season over Tibet from 1980 to 2013 is described on monthly to annual time scales with meteorological observations. Furthermore, four precipitation products are compared to observations over Tibet. These datasets include products derived from the Asian Precipitation-Highly-Resolved Observational Data(APHRO), the Global Precipitation Climatology Centre(GPCC), the University of Delaware(UDel), and the China Meteorological Administration(CMA). The error, relative error, standard deviation, root-mean-square error, correlations and trends between these products for the same period are analyzed with in situ precipitation during the rainy season from May to September. The results indicate that these datasets can broadly capture the temporal and spatial precipitation distribution over Tibet. The precipitation gradually increases from northwest to southeast. The spatial precipitation in GPCC and CMA are similar and positively correlated to observations. Areas with the largest deviations are located in southwestern Tibet along the Himalayas. The APHRO product underestimates, while the UDel, GPCC, and CMA datasets overestimates precipitation on the basis of monthly and inter-annual variation. The biases in GPCC and CMA are smaller than those in APHRO and UDel with a mean relative error lower than 10% during the same periods. The linear trend of precipitation indicates that the increase in precipitation has accelerated extensively during the last 30 years in most regions of Tibet. The CMA generally achieves the best performance of these four precipitation products. Data uncertainty in Tibet might be caused by the low density of stations, complex topography between the grid points and stations, and the interpolation methods, which can also produce an obvious difference between the gridded data and observations. 相似文献
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Jean-Claude Plaziat 《Journal of Paleolimnology》1993,8(2):163-169
Potamids generally live in estuaries, lagoons, and along protected sea shores. However, their ability to colonize intracontinental lakes has been underestimated due to non- or misidentifications. Potamides conicus, the only present lacustrine Potamid currently found in North Africa, belongs to a lagoon-type (thalassoid) malacofauna, dominated by the Cardium Cerastoderma glaucum: this fauna occurs in association with Foraminifera (especially Ammonia beccarii) and Ostracoda (Cyprideis gr. Torosa). Potamids have been found 250 to 900 km from the nearest sea shore: passive dispersal (probably through birds) is the primary dispersal mechanism. Shell morphology and ornamentation can be used to characterize life environment (lacustrine versus marine) but not distance from sea shore. The presence of Potamid-Foraminifera fauna in the fossil record has been interpreted as providing evidence for a sea connection (e.g., gulfs, lagoons). However, more recent paleoecological studies have demonstrated that such assemblages span an ecological gradient from freshwater to hypersaline lacustrine environments. Thus, the occurrence of modern Potamids in lacustrine (in addition to maritime) environments has important implications for Quaternary and Tertiary paleogeographic investigations. Lacustrine Potamids have been recorded from the European Tertiary (France, Spain) and from the Sahara Holocene. More research is required for the better understanding of the distribution and ecology of Potamids in modern and fossil lakes of other continents.This publication is the fifth of a series of papers presented at the Conference on Sedimentary and Paleolimnological Records of Saline Lakes. This Conference was held August 13–16, 1991 at the University of Saskatchewan, Saskatoon, Canada. Dr Evans is serving as Guest Editor. 相似文献