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Soil concentrations and soil-air exchange of organochlorine pesticides along the Aba profile, east of the Tibetan Plateau, western China
Hongxia LIU, Shihua QI, Dan YANG, Ying HU, Feng LI, Jia LIU, Xinli XING
Front Earth Sci. 2013, 7 (4): 395-405.
https://doi.org/10.1007/s11707-013-0404-9
Mianzhu—Aba profile, east of the Tibetan Plateau, was selected to study the occurrence of organochlorine pesticides (OCPs) along an altitudinal gradient. Dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs) and Aldrin, Dieldrin and Endrin (Drins) in surface soils were detected in winter (March) and summer (July). Soil concentrations (ng·g-1, dw) in winter and summer ranged as follws: DDTs, 0.37–179.16 and 0.32–42.57; HCHs, 0.14–10.76 and 0.55–32.71; Drins, N.D–3.99 and 0.02–6.93, respectively. Main soil OCPs were p,p′-DDT, p,p′-DDE, β-HCH and Drins, among which Drins were rarely reported in current literature of the Tibetan Plateau. Higher OCP concentrations in the profile were attributed close to the agricultural fields of the Sichuan Basin, current lindane and non-dicofol DDTs inputs, and also long-range atmospheric transport from abroad. Soil OCP concentrations underwent obvious seasonal variation, with higher DDTs in winter and higher HCHs and Drins in summer. It may be caused by climatic conditions, summer monsoon type, and physico-chemical properties of such contaminants. Though “rest” phenomenon occurred in some sampling sites, HCHs and Drins showed an increasing trend with increasing altitude, while DDTs showed an evident decrease with increasing altitude. The altitudinal distributions of OCPs were all consistent with previous findings in other mountainous regions. A primary fugacity analysis on OCPs soil-air exchange indicated that the profile may be secondary sources for HCHs and Endrin. As with Aldrin, Dieldrin, and DDTs, the profile may be both secondary sources and sinks.
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Climate change and its effect on reference crop evapotranspiration in central and western Inner Mongolia during 1961–2009
Di HE, Yaling LIU, Zhihua PAN, Pingli AN, Liwei WANG, Zhiqiang DONG, Jingting ZHANG, Xuebiao PAN, Peiyi ZHAO
Front Earth Sci. 2013, 7 (4): 417-428.
https://doi.org/10.1007/s11707-013-0381-z
Water resource is one of the major constraints to agricultural production in central and western Inner Mongolia, where are characteristic by arid and semi-arid climate. Reference crop evapotranspiration (ET0) is an important part of water cycle in agricultural ecosystem, which has a direct effect on crop growth and yield. The implications of climate change on ET0 are of high importance for agriculture regarding water management and irrigation scheduling. The aim of this study was to analyze the variations in climate and its effect on ET0 in central and western Inner Mongolia over the period 1961 to 2009. For this purpose, data in ten meteorological stations across study area were collected and the FAO Penman-Monteith 56 method was used. Results showed that the average temperature, maximum temperature and minimum temperature increased by 0.49°C, 0.31°C and 0.70°C per decade during 1961–2009, respectively. In comparison, the daily temperature range decreased by 0.38°C per decade. The air relative humidity, sunshine hour, and 10-m wind speed decreased generally by 0.58%, 40.11 h, and 0.35 m/s per decade, respectively. Annual mean ET0 decreased significantly at a rate of 12.2 mm per decade over the periods, this was mainly due to the decrease in wind speed in the study area. The decrease in wind speed may balance the effect of the increase in air temperature on ET0. Variations in spatial distribution of ET0 and its main controlling factor were also detected among ten stations. Our results suggested that spatial and temporal distribution of ET0 should be considered regarding the optimization of water resource management for agriculture in central and western Inner Mongolia under foreseen climate change.
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Sensitivity studies of high-precision methane column concentration inversion using a line-by-line radiative transfer model
Ci SONG, Jiong SHU, Mandi ZHOU, Wei GAO
Front Earth Sci. 2013, 7 (4): 439-446.
https://doi.org/10.1007/s11707-013-0391-x
Hyper-spectral remote sensing may provide anβeffective solutionβto retrieve the methane (CH4) concentration in an atmospheric column. As a result of exploringβthe absorptive characteristics of CH4,βan appropriate band is selected from hyperspectral data for the detection ofβitsβcolumn concentration with high precision. Following the most recent inversion theory and methods, the line-by-line radiative transfer model (LBLRTM) is employed to forward model the impact of four sensitive factors on inversion precision, including CH4 initial profile, temperature, overlapping gases, and surface albedo. The results indicate that the four optimized factors could improve the inversion precision of atmospheric CH4 column concentration.
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Geostrophic current estimation using altimeter data at ground track crossovers in the northwest Pacific Ocean
Yang YU, Longfei WANG, Ziwei LI, Xuan ZHOU
Front Earth Sci. 2013, 7 (4): 447-455.
https://doi.org/10.1007/s11707-013-0380-0
Geostrophic current comprises a large portion of the ocean current, which plays an important role in global climate change. Based on classic oceanography, geostrophic current can be derived from pressure gradient. Assuming water density to be constant, we can estimate geostrophic current from Absolute Dynamic Topography (ADT). In this paper, we use ADT data obtained from multi-satellite altimeters to extract sea surface tilts along-track at crossover points. The calculated tilts along these two tracks can be converted into orthogonal directions and are used to estimate geostrophic current. In northwest Pacific, computed geostrophic current velocities are evaluated with Argos data. In total, 771 pairs of temporally and spatially consistent Argos measurements along with estimated geostrophic velocity datasets are used for validation. In this study, the effect of different cut-off wavelengths of the low pass filter applied to ADT is discussed. Our results show that a cut-off wavelength of 75 km is the most suitable choice for the study area. The estimated geostrophic velocity and the Argos measurement are in good agreement with each other, with a correlation coefficient of 0.867 for zonal component, and 0.734 for meridional one. Furthermore, an empirical relationship between the estimated geostrophic velocity and Argos measurement is derived, providing us a favorable and convenient approach to estimate sea surface flow velocity from the geostrophic velocity derived from altimeter data. The experimental application of the derived method on Kuroshio reveals reasonable results compared with previous studies.
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Global detection of large lunar craters based on the CE-1 digital elevation model
Lei LUO, Lingli MU, Xinyuan WANG, Chao LI, Wei JI, Jinjin ZHAO, Heng CAI
Front Earth Sci. 2013, 7 (4): 456-464.
https://doi.org/10.1007/s11707-013-0361-3
Craters, one of the most significant features of the lunar surface, have been widely researched because they offer us the relative age of the surface unit as well as crucial geological information. Research on crater detection algorithms (CDAs) of the Moon and other planetary bodies has concentrated on detecting them from imagery data, but the computational cost of detecting large craters using images makes these CDAs impractical. This paper presents a new approach to crater detection that utilizes a digital elevation model instead of images; this enables fully automatic global detection of large craters. Craters were delineated by terrain attributes, and then thresholding maps of terrain attributes were used to transform topographic data into a binary image, finally craters were detected by using the Hough Transform from the binary image. By using the proposed algorithm, we produced a catalog of all craters≥10 km in diameter on the lunar surface and analyzed their distribution and population characteristics.
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Carbon emission trading system of China: a linked market vs. separated markets
Yu LIU, Shenghao FENG, Songfeng CAI, Yaxiong ZHANG, Xiang ZHOU, Yanbin CHEN, Zhanming CHEN
Front Earth Sci. 2013, 7 (4): 465-479.
https://doi.org/10.1007/s11707-013-0385-8
The Chinese government intends to upgrade its current provincial carbon emission trading pilots to a nationwide scheme by 2015. This study investigates two of scenarios: separated provincial markets and a linked inter-provincial market. The carbon abatement effects of separated and linked markets are compared using two pilot provinces of Hubei and Guangdong based on a computable general equilibrium model termed SinoTERMCo2. Simulation results show that the linked market can improve social welfare and reduce carbon emission intensity for the nation as well as for the Hubei-Guangdong bloc compared to the separated market. However, the combined system also distributes welfare more unevenly and thus increases social inequity. On the policy ground, the current results suggest that a well-constructed, nationwide carbon market complemented with adequate welfare transfer policies can be employed to replace the current top-down abatement target disaggregation practice.
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Urban energy consumption and related carbon emission estimation: a study at the sector scale
Weiwei LU, Chen CHEN, Meirong SU, Bin CHEN, Yanpeng CAI, Tao XING
Front Earth Sci. 2013, 7 (4): 480-486.
https://doi.org/10.1007/s11707-013-0363-1
With rapid economic development and energy consumption growth, China has become the largest energy consumer in the world. Impelled by extensive international concern, there is an urgent need to analyze the characteristics of energy consumption and related carbon emission, with the objective of saving energy, reducing carbon emission, and lessening environmental impact. Focusing on urban ecosystems, the biggest energy consumer, a method for estimating energy consumption and related carbon emission was established at the urban sector scale in this paper. Based on data for 1996–2010, the proposed method was applied to Beijing in a case study to analyze the consumption of different energy resources (i.e., coal, oil, gas, and electricity) and related carbon emission in different sectors (i.e., agriculture, industry, construction, transportation, household, and service sectors). The results showed that coal and oil contributed most to energy consumption and carbon emission among different energy resources during the study period, while the industrial sector consumed the most energy and emitted the most carbon among different sectors. Suggestions were put forward for energy conservation and emission reduction in Beijing. The analysis of energy consumption and related carbon emission at the sector scale is helpful for practical energy saving and emission reduction in urban ecosystems.
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Carbonate formation and water level changes in a paleo-lake and its implication for carbon cycle and climate change, arid China
Yu LI, Nai’ang WANG, Zhuolun LI, Xuehua ZHOU, Chengqi ZHANG, Yue WANG
Front Earth Sci. 2013, 7 (4): 487-500.
https://doi.org/10.1007/s11707-013-0392-9
Carbonate deposition is a main inorganic carbon sink in lakes, which varies depending on climate change and internal lake dynamics. Research on the relationship between lake carbonate and climate will help to understand mechanisms of carbon cycle in lacustrine systems. The approach of this study is to explicitly link carbonate formation with Holocene long-term climate change and lake evolution in a paleo-lake (Zhuye Lake), which is a terminal lake of a typical inland drainage basin in arid China. This paper presents analysis on grain-size, carbonate content and mineralogical composition of sediment samples from different locations of Zhuye Lake. The results show that calcite and aragonite are two main components for the lake carbonate, and the carbonate enrichment is associated with lake expansion during the Late Glacial and early to middle Holocene. Holocene lake expansion in arid regions of China is usually connected with high basin-wide precipitation that can strengthen the basin-wide surface carbonate accumulation in the terminal lake. For this reason, Zhuye Lake plays a role of carbon sinks during the wet periods of the Holocene.
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The ground deformation field induced by a listric thrust fault with an overburden soil layer
Shaogang ZENG, Yong’en CAI
Front Earth Sci. 2013, 7 (4): 501-507.
https://doi.org/10.1007/s11707-013-0383-x
The surface deformation field induced by a listric thrust fault with a thick, overburden soil layer is studied in this paper by the finite element method (FEM). The results show: (a) The maximum slip induced by the buried fault is not located at upper tip of the fault, but below it. (b) The vertical displacement changes remarkably near the fault, forming a fault scarp. With the increase of the soil layer thickness, the height of the scarp is decreased for the same earthquake magnitude. (c) The strong strain zone on the surface is localized near the projection of the fault tip on the ground surface. The horizontal strains in the zone are in tension above the hanging wall and in compression above the foot wall, and the vertical strains in the zone are vice versa, which is favorable for tensile-shear, compression-shear fissures above hanging wall and foot wall, respectively.
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