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1.
PEIZhiyong OUYANGHua ZHOUCaiping XUXingliang 《地理学报(英文版)》2003,13(4):429-437
In this paper, the CO2 concentrations profile from 1.5 m depth in soil to 32 m height in atmosphere were measured from July 2000 to July 2001 in an alpine grassland ecosystem located in the permafrost area on the Tibetan Plateau, which revealed that CO2 concentrations varied greatly during this study period. Mean concentrations during the whole experiment in the atmosphere were absolutely lower than the CO2 concentrations in soil, which resulted in CO2 emissions from the alpine steppe soil to the atmosphere. The highest CO2 concentration was found at a depth of 1.5 m in soil while the lowest CO2 concentration occurred in the atmosphere. Mean CO2 concentrations in soil generally increased with depth. This was the compositive influence of the increasing soil moistures and decreasing soil pH, which induced the increasing biological activities with depth. Temporally, the CO2 concentrations at different layers in air remained a more steady state because of the atmospheric turbulent milking. During the seasonal variations, CO2 concentrations at surface soil interface showed symmetrical patterns, with the lowest accumulation of CO2 occurring in the late winter and the highest CO2 concentration in the growine seasons. 相似文献
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ShengYun Chen Qian Zhao WenJie Liu Zhao Zhang Shuo Li HongLin Li ZhongNan Nie LingXi Zhou ShiChang Kang 《寒旱区科学》2018,10(1):69-79
Nitrous oxide(N_2 O) is one of the most important greenhouse gases in the atmosphere; freeze–thaw cycles(FTCs) might strongly influence the emission of soil N_2 O on the Qinghai–Tibetan Plateau(QTP). However, there is a lack of in situ research on the characteristics of soil N_2 O concentration and flux in response to variations in soil properties caused by FTCs.Here, we report the effect of FTC-induced changes in soil properties on the soil N_2 O concentration and flux in the permafrost region of the higher reaches of the Shule River Basin on the northeastern margin of the QTP. We measured chemical properties of the topsoil, activities of soil microorganisms, and air temperature(AT), as well as soil N_2 O concentration and flux, over an annual cycle from July 31, 2011, to July 30, 2012. The results showed that soil N_2 O concentration was significantly affected by soil temperature(ST), soil moisture(SM), soil salinity(SS), soil polyphenol oxidase(SPO), soil alkaline phosphatase(SAP), and soil culturable actinomycetes(SCA), ranked as SMSSSTSPOSAPSCA, whereas ST significantly increased soil N_2 O flux, compared with SS. Overall, our study indicated that the soil N_2 O concentration and flux in permafrost zone FTCs were strongly affected by soil properties, especially soil moisture, soil salinity, and soil temperature. 相似文献
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1 Background The growing realization of anthropogenic climate change has focused the attention of the scientific community, policymakers and the general public on the rising concentration of greenhouse gases, especially CO2 in the atmosphere, and on the c… 相似文献
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Ahmad Ismail Syaizwan Zahmir Zulkifli Ferdius Mohamat Yusuff Usuki Yasuteru Kitajima Sachiko Arizono Koji 《湿地科学》2007,5(4):322-325
This study was conducted to assess the existing concentration of 17β-estradiol(E2)in the surface water samples collected from rivers and lakes around Klang Valley,Malaysia.E2,which is a natural feminizing chemical produced in female organisms,regularly used to compare with other environmental estrogens because they behave similarly and react effectively as a hormone at a very low concentration.It was found that the average concentration of E2 in the aquatic environment of Klang Valley was(14.08 ±3.67)pg/mL,which was 14 times higher than those in the Japanese aquatic environment in this study.The river system had the average concentration of(20.02±5.26)pg/mL while the lake had an average concentration of(5.91±3.39)pg/mL.The E2 concentration was presumed high if the sources occurred nearby the area.Current levels of E2 in the aquatic environment may possess threats to existing aquatic organisms.Since high level of E2 has been discovered in the aquatic environment around Klang Valley,further studies and monitoring of E2 and other EDCs concentrations are needed to determine their levels in Malaysian aquatic environment and help to control these chemicals pollution in the aquatic environment. 相似文献
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Carbon dioxide(CO_2) is a major climate forcing factor, closely related to human activities. Quantifying the contribution of CO_2 emissions to the global radiative forcing(RF) is therefore important to evaluate climate effects caused by anthropogenic and natural factors. China, the United States(USA), Russia and Canada are the largest countries by land area, at different levels of socio-economic development. In this study, we used data from the CarbonTracker CO_2 assimilation model(CT2017 data set) to analyze anthropogenic CO_2 emissions and terrestrial ecosystem carbon sinks from 2000 to 2016. We derived net RF contributions and showed that anthropogenic CO_2 emissions had increased significantly from 2000 to 2016, at a rate of 0.125 PgC yr~(-1). Over the same period, carbon uptake by terrestrial ecosystems increased at a rate of 0.003 PgC yr~(-1). Anthropogenic CO_2 emissions in China and USA accounted for 87.19% of the total, while Russian terrestrial ecosystems were the largest carbon sink and absorbed 14.69 PgC. The resulting cooling effect was-0.013 W m~(-2) in 2016, representing an offset of-45.06% on climate warming induced by anthropogenic CO_2. This indicates that net climate warming would be significantly overestimated if terrestrial ecosystems were not included in RF budget analyses. In terms of cumulative effects, we analyzed RFs using reference atmospheres of 1750, at the start of the Industrial Revolution, and 2000, the initial year of this study. Anthropogenic CO_2 emissions in the study area contributed by + 0.42 W m~(-2) and +0.32 W m~(-2) to the global RF, relative to CO_2 levels of 1750 and 2000, respectively. We also evaluated correlations between global mean atmospheric temperature and net, anthropogenic and natural RFs. We found that the combined(net) RF caused by CO_2 emissions accounted for 30.3% of global mean temperature variations in 2000–2016. 相似文献
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<正> The reconstruction of air trapped in ice cores provides us the most di-rect information about atmospheric CH_4 variations in the past history.Ice corerecords from the“Three Poles(Antarctica,Greenland and Tibetan Plateau)”re-veal the detailed fluctuations of atmospheric CH_4 concentration with time and areallowed to quantify the CH_4 differences among latitudes.These data are indis-pensably in the farther study of the relationship between greenhouse gases andclimatic change,and of the past changes in terrestrial CH_4 emissions.Ice coresreconstruction indicates that atmospheric CH_4 concentration has increased quicklysince industrialization,and the present day's level of atmospheric CH_4(1800 pp-by)is unprecedented during the past Glacial-Interglacial climate cycles. 相似文献
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Three types of rainfall (storm, moderate and slight rainfall) in the Beijing area were simulated by the Weather Research and Forecast (WRF3.2) model coupled with Milbrandt-two-moment cloud microphysics scheme, to explore the effect of aerosols on clouds and precipitation under continental and maritime aerosol scenarios. Results indicate that an increase of aerosols has various effects on clouds and precipitation. (1) The amount of surface precipitation is obviously affected. With an increase of aerosol concentration, the 48-hr total precipitation of storm and moderate rainfall decreased by 23% and 16.6%, respectively, and the 24-hr total precipitation of slight rainfall decreased by 14.0%. (2) The distribution of surface precipitation is also clearly affected. The average precipitation for a rain storm increases in most parts of western Beijing and decreases by more than 20 mm in most parts of eastern Beijing with increasing aerosol concentration. The average precipitation of moderate rainfall decreases by 0.1–5 mm in most parts of the Beijing area. The effect of increased aerosol concentration is weak for slight rainfall distribution in the study area. (3) With an increase of aerosol concentration, a narrower width and lower precipitation peak value are found in the storm rainfall, and its duration is prolonged for the high aerosol concentration. An earlier precipitation termination of moderate rainfall is found with increasing aerosol concentration. (4) The upper-air hydrometeors vary with aerosol concentration. For storm and moderate rainfall, significantly higher cloud water concentration and lower rain water were found under the continental aerosol scenario. 相似文献
8.
CONCENTRATION CHARACTERISTICS OF SOLUBLE IMPURITIES IN THE SURFACE SNOW OF COLLINS ICE CAP, KING GEORGE ISLAND, ANTARCTICA 
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下载免费PDF全文 Measurements carried out for the upper 10m firn/ice obtained at the main dome of Collins Ice Cap, King George Island, Antarctica revealed the direct relation of soluble impurities of snow mass to the composition of atmosphere aerosols. It was indicated that sea salt source dominates the atmosphere aerosol around Collins Ice Cap. The simultaneous variation shown by the concentration profiles of Na~+, K~+, Mg~(2+), Ca~(2+), SO_4~(2-), CI~-, Br~- and very close EF values (≈1) suggested their common marine source and similar deposition process. Besides the possible surface contamination,NH_4~+varied uniformly along deeper part of the core in concentration, which could be considered as background value of ammonium. A satisfactory explanation for NO_3~- concentration profile has not reached at present. 相似文献
9.
北极涛动对华北沙尘暴频次的影响 总被引：2，自引：0，他引：2
This study has investigated the influence of Arctic Oscillation (AO) on dust storm frequency in North China in spring seasons during 1961 2007.There is a significant linkage between dust storm frequency and AO;a negative (positive) AO phase is related to an in-creased (decreased) dust storm frequency in North China.This relationship is closely related to changes in the cold air activity in Mongolia.The cold air activity exerts large impacts on the dust storm frequency;the frequency of cold air activity over Mongolia not only positively cor-relates with the dust storm frequency in North China,but also shows a long-term decreasing trend that is an important reason for the long-term decreasing of dust storm frequency in North China.The AO has large influence on the frequency of cold air activity over Mongolia;a negative (positive) AO phase is highly related to an increased (decreased) frequency of cold air activity over Mongolia,which results in an increased (decreased) dust storm frequency in North China. 相似文献
10.
LIANGFuyuan SONGLinhua TANGTao 《地理学报(英文版)》2003,13(2):250-256
Lunan stone forest is a kind of typical karst in China,Which is mainly developed under red soil.In the winter of 1999,three study sites were chosen in stone forest national park according to vegetation cover,geomporphologic location and soil types,CO2 concentration was measured with Gastec punp at different dephts of soil (20,40,60cm) and at the same time soil samples were gatered and soil properties such as soil moisure,pH,soil organic content were analyzed and the total nmuber of viable microbes were counted in laboratory,In the study,dependent variable was chosen as the mean soil log(PCO2),and soil properties were chosen as the independent variables.Multiple stepwise regression analysis showed that the totla amount of microbes and soil moisture are the best indicators of the CO2 production,With the equation LOG(PCO2)=-0.039(TNM)-0.056 (Mo) 1.215 accounting for 86% of the variation of the soil CO2 concentration,where TNM is the total number of microbes in teh soil and Mo is the moisture of soil sample. 相似文献
11.
Based on climate material, the simplified terrestrial carbon cycle balance (TCCB) model was established, which is semi-mechanism and semi-statistics. Through TCCB model, our estimate indicates that the southeastern part of the Tibetan Plateau has much higher carbon content, and we have calculated the litter carbon pool, NPP, carbon fluxes and described their spatial characteristics in this region. Based on the TCCB model simulation, NPP in Tibet is 1.73×108 tC/a, soil organic input rate is 0.66×108 tC/a, litter mineralization rate is 1.07×108 tC/a, vegetation litterfall rate is 1.73×108 tC/a, the litter carbon pool is 7.26×108 tC, and soil decomposition rate is 309.54×108 tC/a. The carbon budget was also analyzed based on the estimates of carbon pool and fluxes. The spatial distributions of carbon pools and carbon fluxes in different compartments of terrestrial ecosystem were depicted with map respectively in Tibet. The distribution of NPP, vegetation litterfall rate, litter, litter mineralization rate, soil organic input rate and the soil decomposition rate were abstracted with temperature, precipitation, fractional vegetation and land feature. 相似文献
12.
青藏高原自然植被总生物量的估算与净初级生产量的潜在分布* 总被引：32，自引：0，他引：32
以800多块样地资料及森林和草地资源调查数据为基础,按县级为单位估算了青海和西藏两省区的自然植被总生物量,分别为2.586×108t和1.282×109t.建立的QZNPP模型显示,随着温度的增加,生物生产量呈S型曲面递增,且其递增速率随降水量增加而加快;当年均温度0℃～10℃和年降水量400mm～1000mm时,生物生产量增长最快;当年均温度>11℃和年降水量>1 100mm时,生物生产量趋向于20t/hm2·a;在年均温度<0℃时,相对降水量的增加,生物生产量呈缓慢的递减趋势,说明这时温度是影响生物生产量的主导因子。两省区115个县的生物量现实分布图显示,生物量最高值出现在西藏墨脱,其次是西藏的察隅、波密、林芝和米林,青藏高原中部及西北部的广阔地区最低。青藏高原自然植被净初级生产量最小值为0,最大值为20t/hm2·a,全区平均为6.03t/hm2·a,低于世界陆地植被的平均水平 相似文献
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Anthropogenic mercury accumulation in lake sediments has been studied extensively, but natural processes that controlled mercury accumulation in the past are still poorly understood. We present a 17,300-year record of mercury accumulation in the sediments of Lake Hambre, southernmost Patagonia, Chile (53°S, 70°W), in combination with an investigation of environmental changes in the region. Mercury accumulation in the remote pristine lake varied appreciably, as much as 16×, exceeding the anthropogenic forcing of atmospheric mercury fluxes by a factor of 3–5. Principal Component Analysis revealed that short-term variations were not related to changes in atmospheric mercury deposition or to fluxes of mineral soil into the lake. Instead, there was significant covariation between short-term changes in mercury and catchment-derived trace elements, e.g. copper and yttrium, throughout the past 17,000 years. Covariation between mercury and carbon concentration in some parts of the record suggests that fluxes of particulate and dissolved organic matter from the catchment to the lake account for short-term variations in mercury accumulation. Nevertheless, over the long term, there is no common trend for mercury accumulation and organic matter flux. The median mercury accumulation rate was rather constant (29 μg m?2 a?1), whereas the flux of terrestrial organic matter into the lake increased through time. We hypothesize that this was a consequence of a progressive decrease in the input of terrestrial organic matter-bound mercury through time. Whereas production of terrestrial organic matter increased over the long term because of development of catchment vegetation and soils, following glacier retreat, amounts of mercury, copper and yttrium provided by atmospheric deposition and bedrock weathering remained relatively constant. As a consequence, despite increased fluxes of terrestrial organic matter to the lake, fluxes of mercury remained constant. 相似文献
15.
中国东南部植被NPP的时空格局变化及其与气候的关系研究 总被引：2，自引：0，他引：2
基于2001~2010年MOD17A3年均NPP数据和气象站点气温、降水资料,利用GIS空间分析技术和数理统计方法研究中国东南部植被NPP的时空格局、动态变化及与气候要素的关系。结果表明,中国东南部植被年均NPP总体上呈现从南到北、由东至西逐渐减少的分布,不同植被类型的NPP存在明显差异,以常绿阔叶林最高,落叶针叶林最低。2001~2010年间,植被NPP整体上略有减少。空间上植被NPP在南部地区明显减少,而在北部地区明显增加。植被NPP与降水和气温的相关性均表现出明显的地域差异。 相似文献
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黄河源区高寒草地土壤有机碳储量及分布特征 总被引：14，自引：0，他引：14
选择位于黄河源区的青海省果洛藏族自治州为研究区,利用第二次全国土壤普查所得的土壤剖面数据以及55个典型土壤剖面的地理位置、土层深度、有机质含量、面积、理化分析数据和1:50万数字化土壤类型图,在GIS的支持下利用土壤类型法对黄河源区草地土壤碳库进行了估算。结果表明,黄河源区土壤碳密度较高,平均土壤有机碳密度为29.97 kg/m2,高寒草地土壤有机碳库主要由高山草甸土和高山草原土的有机碳库构成,研究区土壤有机碳总储量达15×108tC。区域草地土壤有机碳密度及储量呈明显的水平和垂直分异规律。 相似文献
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兴国县森林土壤有机碳库及其与环境因子的关系 总被引：23，自引：5，他引：18
确定土壤有机碳的储量、空间分布 ,对土壤碳循环的研究具有重要意义。根据江西兴国县 84个样点和 50个剖面的采样数据、土壤有机质含量 ,统计土壤各类型分布面积 ,估算了土壤有机碳库。研究结果表明 ,兴国县森林土壤有机碳在 2 0cm深度内总量为 559 38× 1 0 4t,平均有机碳密度为 2 47kgC/m2 ,在 1 0 0cm深度内总量为 1 4 37 1 9× 1 0 4t,平均有机碳密度为6 36kgC/m2 。其分布特征是 :西北部和东北部高 ,中部和西南部低。土壤有机碳含量深受母岩、植被和地形影响 ,在表层 (0～ 2 0cm) ,坡向和有机碳含量呈显著正相关关系 ;海拔与有机碳含量呈极显著正相关关系 ;在剖面 (0～ 1 0 0cm) ,海拔和有机碳含量的相关关系达极显著水平 ,有机碳含量与坡向、坡度之间无明显的相关关系。 相似文献
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安徽省土壤有机碳空间差异及影响因素 总被引：26，自引：2，他引：26
区域土壤碳储量和碳固定潜力及影响因素分析是全球变化中碳循环研究的重要前沿问题。本文采用第二次土壤普查资料,研究了安徽省不同类型土壤的有机碳密度和碳库,分析了影响土壤有机碳分布的自然和人为因素。结果表明,安徽土壤有机碳库为0.71Pg,表层土壤有机碳库为0.28Pg;土壤平均有机碳密度达117.54 t/hm2,碳密度的空间分布为:皖南山区>皖西大别山区>沿长江平原>江淮丘陵区>淮北平原区;气候和植被控制着表层土壤有机碳的省域分布,降水与土壤有机碳含量呈正相关。地形和母质影响土壤亚类间有机碳的差异;土壤总氮与土壤有机碳呈极显著相关,平原区土壤粘粒含量与表层土壤有机碳固定有较大关系。 相似文献
20.
Torbern Tagesson Jonas Ardö Idrissa Guiro Ford Cropley Cheikh Mbow Stephanie Horion 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2016,116(2):93-109
Africa is a sink of carbon, but there are large gaps in our knowledge regarding the CO2 exchange fluxes for many African ecosystems. Here, we analyse multi-annual eddy covariance data of CO2 exchange fluxes for a grazed Sahelian semi-arid savanna ecosystem in Senegal, West Africa. The aim of the study is to investigate the high CO2 exchange fluxes measured at the peak of the rainy season at the Dahra field site: gross primary productivity and ecosystem respiration peaked at values up to ?48 μmol CO2 m?2 s?1 and 20 μmol CO2 m?2 s?1, respectively. Possible explanations for such high fluxes include a combination of moderately dense herbaceous C4 ground vegetation, high soil nutrient availability and a grazing pressure increasing the fluxes. Even though the peak net CO2 uptake was high, the annual budget of ?229 ± 7 ± 49 g C m?2 y?1 (±random errors ± systematic errors) is comparable to that of other semi-arid savanna sites due the short length of the rainy season. An inter-comparison between the open-path and a closed-path infrared sensor indicated no systematic errors related to the instrumentation. An uncertainty analysis of long-term NEE budgets indicated that corrections for air density fluctuations were the largest error source (11.3% out of 24.3% uncertainty). Soil organic carbon data indicated a substantial increase in the soil organic carbon pool for the uppermost .20 m. These findings have large implications for the perception of the carbon sink/source of Sahelian ecosystems and its response to climate change. 相似文献