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Long-term impacts of land-use change on dynamics of tropical soil carbon and nitrogen pools

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Journal of Environmental Sciences 2004年第2期16卷 256-261页

作者： YANGJing-cheng HUANGJian-hui PANQing-min TANGJian-wei HANXing-guo LaboratoryofQuantitativeVegetationEcology InstituteofBotanyChineseAcademyofSciencesBeijing100093China. XishuangbannaTropicalBotanicalGarden ChineseAcademyofSciencesMengla666303China

Land-use changes, especially the conversion of native forest vegetation to cropland and plantations in tropical region, can alter soil C and N pools and N availability for plant uptake. Deforestation, followed by shifting cultivation and establishment of rubber tree plantation, is a common land-use change in Xishuangbanna, southwest China. However the influence of this kind of land-use change on soil C and N dynamics in this region remains poorly understood. This study was conducted to assess the effects of land-use change on soil C and N pools. Soil samples were collected on five adjacent plots, which belong to three land-use types including secondary forest-an acuminate banana(Musa itinerans) secondary forest and a male bamboo(Dendrocalamus membranaceae) secondary forest, shifting cultivation, and rubber tree (Hevea brasiliensis (H.B.K.) Muell. Arg.) plantation(one plot is 3-year-old, and another is 7-year-old). We measured soil bulk density (BD), pH value, moisture content and concentrations of soil organic carbon(SOC), total soil nitrogen(TSN), and inorganic N(NO - 3-N and NH + 4-N ) at 0—3, 3—20, 20—40 and 40—60 cm depths, and calculated C and N pools in 0—20, 20—40, 40—60, and 0—60 cm soil layers. Compared with the adjacent secondary forests, shifting cultivation and establishment of rubber tree plantations resulted in significant decline in concentrations and stocks of SOC and TSN in 0—20 and 0—60 cm soil layers, and increase in pH and bulk density at 0—3, 3—20, and 20—40 cm depths. Soil moisture content decreased only in 0—20 cm surface soils in shifting cultivation and plantations. The dynamics of mineral N was much more complex, which had different trends among depths and ecosystems. Compared with the secondary forests, SOC stocks in 0—20 cm surface soils in shifting cultivation and rubber tree plantations(3-year-old plantation and 7-year-old plantation) decreased by 34.0%, 33%, and 23%; and TSN stocks decreased by 32 2%, 20.4%, and 20.4%, respect

关键词： soil organic carbon(SOC) total soil nitrogen(TSN) inorganic nitrogen land-use change tropical soil Xishuangbana

Validation of MODIS aerosol retrievals and evaluation of potential cloud contamination in East Asia

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Journal of Environmental Sciences 2004年第5期16卷 832-837页

作者： XIAXiang-ao CHENHong-bin WANGPu-cai LAGEO InstituteofAtmosphericPhysicsChineseAcademyofSciencesBeijing100029China

MODIS aerosol retrievals onboard Terra/Aqua and ground truth data obtained from AERONET(Aerosol Robtic Network) solar direct radiance measurements are collocated to evaluate the quality of the former in East Asia. AERONET stations in East Asia are separated into two groups according to their locations and the preliminary validation results for each station. The validation results showed that the accuracy of MODIS aerosol retrievals in East Asia is a little worse than that obtained in other regions such as Eastern U.S., Western Europe, Brazil and so on. The primary reason is due to the improper aerosol model used in MODIS aerosol retrieval algorithm, so it is of significance to characterize aerosol properties properly according to long term ground-based remote sensing or other relevant in situ observations in order to improve MODIS retrievals in East Asia. Cloud contamination is proved to be one of large errors, which is demonstrated by the significant relation between MODIS aerosol retrievals versus cloud fraction, as well as notable improvement of linear relation between satellite and ground aerosol data after potential cloud contamination screened. Hence, it is suggested that more stringent clear sky condition be set in use of MODIS aerosol data. It should be pointed out that the improvement might be offset by other error sources in some cases because of complex relation between different errors. Large seasonal variation of surface reflection and uncertainties associated with it result in large intercepts and random error in MODIS aerosol retrievals in northern inland of East Asia. It remains to be a big problem to retrieve aerosols accurately in inland characterized by relatively larger surface reflection than the requirement in MODIS aerosol retrieval algorithm.

关键词： MODIS aerosol retrieval validation AERONET

Sediment distribution pattern mapped from the combination of objective analysis and geostatistics in the large shallow Taihu Lake, China

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Journal of Environmental Sciences 2004年第6期16卷 908-911页

作者： LUOLian-cong QINBo-qiang ZHUGuang-wei NanjingInstituteofGeography＆Limnology ChineseAcademyofSciencesNanjing210008China

Investigation was made into sediment depth at 723 irregularly scattered measurement points which cover all the regions in Taihu Lake, China. The combination of successive correction scheme and geostatistical method was used to get all the values of recent sediment thickness at the 69×69 grids in the whole lake. The results showed that there is the significant difference in sediment depth between the eastern area and the western region, and most of the sediments are located in the western shore-line and northern regimes but just a little in the center and eastern parts. The notable exception is the patch between the center and Xishan Island where the maximum sediment depth is more than 4.0 m. This sediment distribution pattern is more than likely related to the current circulation pattern induced by the prevailing wind-forcing in Taihu Lake. The numerical simulation of hydrodynamics can strong support the conclusion. Sediment effects on water quality was also studied and the results showed that the concentrations of TP, TN and SS in the western part are obviously larger than those in the eastern regime, which suggested that more nutrients can be released from thicker sediment areas.

关键词： objective analysis geostatistics sediment distribution Taihu Lake

Heavy-metal contents in suspended solids of Meiliang Bay,Taihu Lake and its environmental significances

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Journal of Environmental Sciences 2005年第4期17卷 672-675页

作者： ZHUGuang-wei CHIQiao-qiao QINBo-qiang WANGWen-min NanjingInstituteofGeographyandLimnology ChineseAcademyofSciencesNanjing210008China JiangxiAgriculturalUniversity Nanchang330045China NanjingInstituteofGeographyandLimnology ChineseAcademyofSciencesNanjing210008China／／GraduateChina SchoolofChineseAcademyofSciences Beijing100039

Surface water was taken from river mouth to the central area of Meiliang Bay, Taihu Lake, a large shallow eutrophic lake in China. Suspended solids were condensed by centrifugation 25 L surface water samples from each selected site. Suspended solids and surface sediments were further freeze-dried and microwave digested before determining the metals by ICP-AES. Among the metals analyzed in suspended solids and sediments, contents of Cr, Cu, Mn, Ni, and Zn in suspended solids were significantly higher than those in sediments while contents of Al, Ba, Be, Ca, Co, Fe, K, Mg, Pb, and V in suspended solids were 10%—30% higher than those in sediments. Sr and Ti contents in suspended solids and sediments were very similar. Na content in suspended solids was lower than that in sediments. Heavy metals were significantly accumulated in suspended solids. From the river mouth to the center of Meiliang Bay, contents of Cr, Cu, Pb, and Zn in suspended solids showed a gradual decreasing trend indicating the river(Zhihugang River) still discharged large quantity of heavy metals to Meiliang Bay. The study suggests that the geochemical behaviors and ecological effects of heavy metals in suspended solids may serve as a good indicator for the pollution of lake.

关键词： shallow lakes suspended solids heavy metals Taihu Lake

Release behavior of copper and zinc from sandy soils

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Journal of Environmental Sciences 2005年第4期17卷 566-571页

作者： ZHANGMing-kui XIAYi-ping CollegeofNaturalResourceandEnvironmentalSciences ZhejiangUniversityHangzhou310029China CollegeofAgricultureandLifeSciences ZhejiangUniversityHangzhou310029China

The concentrations and chemical forms of copper(Cu) and zinc(Zn) in surface soils directly influence the movement of Cu and Zn. In this study, thirteen sandy soil samples with a wide range of total Cu and Zn concentrations were collected for evaluating the relationships between Cu and Zn release and extraction time, ratio of soil to water, pH and electrolyte types. The results indicated that Cu released in batch extraction that represents long-term leaching was mainly from exchangeable, and carbonate bound Cu fractions, and Zn released in the batch extraction was mainly from its carbonate bound fraction. However, the Cu and Zn leached from the soils using the column leaching that represents short-term leaching were mainly from their exchangeable fractions. Soil column leaching at different pH values indicated that the amounts of leached Zn and Cu were greatly affected by pH. The Cu and Zn release experiments with varying extraction times and ratio of soil to water suggest that long-term water-logging in the soils after rain may increase contact time of the soils with water and the release of Cu and Zn to water from the soils, and total amounts of Cu or Zn released from the soils increase, but the Cu or Zn concentration in the surface runoff decrease with increasing rainfall intensity. The increased Ca concentration in soil solution increased stability of organic matter-mineral complexes and might decrease the dissolution of organic matter, and thus decreased the release of Cu-binding component of organic matter. However, high concentration of Na in the soil solution increased the dispersion of the organic matter-mineral complexes and increased dissolution of organic matter and the release of Cu from the soils.

关键词： release behavior copper zinc sandy soil

Locating the Polar Cap Boundary of Postnoon Sector from Observations of 630.0 nm Auroral Emission at Zhongshan Station

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Wuhan University Journal of Natural Sciences 2002年第1期7卷 59-64页

作者： Liu Li-gang 1, Ai Yong 1, Liu Rui-yuan 2, Yang Hui-gen 2 1. School of Electronic Information, Wuhan University, Wuhan 430072, Hubei, China 2. Polar Research Institute of China, Shanghai 200129, China School of Electronic Information Wuhan University Wuhan Hubei China Polar Research Institute of China Shanghai China

We studied the ground observations of 630.0 nm auroral emission at Zhongshan Station to determine the polar cap boundary with the latitudinal profile of emission intensity. The open-closed field time boundary is assumed to lie at the boundary between polar rain and plasma sheet precipitation. We assume that nonprecipitation-dependent sources of 630.0 nm emission cause a spatially uniform luminosity in the polar cap and that auroral zone luminosity is also spatially uniform. Therefore we determine the location of the polar cap boundary of postnoon sector from the auroral emission data each time by finding the best fit of the observations to a step function in latitude and we produce a time series of the location of the polar cap boundary. The average error of the practice in the paper is less than 0.8 degree.

关键词： polar cap boundary aurora Zhongshan Station

Thermodynamics of phenanthrene partition into solid organic matter from water

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Journal of Environmental Sciences 2005年第2期17卷 185-189页

作者： CHENBao-liang ZHULi-zhong TAOShu DepartmentofEnvironmentalSciences ZhejiangUniversityHangzhou310028China DepartmentofUrbanandEnvironmentalSciences PekingUniversityBeijing100871China

The thermodynamic behavior of organic contaminants in soils is essential to develop remediation technologies and assess risk from alternative technologies. Thermodynamics of phenanthrene partition into four solids(three soils and a bentonite) from water were investigated. The thermodynamics parameters(ΔH, ΔG o, ΔS o,) were calculated according to experimental data. The total sorption heats of phenanthrene to solids from water ranged from -7.93 to -17.1 kJ/mol, which were less exothermic than the condensation heat of phenanthrene-solid(i.e., -18.6 kJ/mol). The partition heats of phenanthrene dissolved into solid organic matter ranged from 23.1 to 32.2 kJ/mol, which were less endothermic than the aqueous dissolved heat of phenanthrene(i.e., 40.2 kJ/mol), and were more endothermic than the fusion heat of phenanthrene-solid(i.e., 18.6 kJ/mol). The standard free energy changes, ΔG o, are all negative which suggested that phenanthrene sorption into solid was a spontaneous process. The positive values of standard entropy changes, ΔS o, show a gain in entropy for the transfer of phenanthrene at the stated standard state. Due to solubility-enhancement of phenanthrene, the partition coefficients normalized by organic carbon contents decrease with increasing system temperature(i.e., lnK oc =-0.284lnS+9.82(n=4, r 2=0.992)). The solubility of phenanthrene in solid organic matter increased with increasing temperatures. Transports of phenanthrene in different latitude locations and seasons would be predicted according to its sorption thermodynamics behavior.

关键词： soil bentonite phenanthrene sorption thermodynamics

Eco-environment contribution of agroforestry to agriculture development in the plain area of China—Huai'an Prefecture, Jiangsu Province as the case study area

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Journal of Environmental Sciences 2005年第2期17卷 327-331页

作者： RENHong-chang LUYong-long LIUCan MENGQing-hua SHIYa-juan ResearchCenterforEco-EnvironmentalSciences ChineseAcademyofSciencesBeijing100085China／／AcademyofForestInventoryandPlanningStateForestryAdministrationBeijing100714China ResearchCenterforEco-EnvironmentalSciences ChineseAcademyofSciencesBeijing100085China ChinaNationalForestryEconomicsandDevelopmentResearchCenter Beijing100714China AcademyofForestInventoryandPlanning StateForestryAdministrationBeijing100714China

For improving the environmental quality and ensuring supply of wood and non-timber forest products, many forests have been planted in plain areas of China. Scientists have studied their benefits, almost all of the approaches were based on fixed-point data, and few was considered on the non-efficient factors and temporal scale effects. This paper studies the positive and negative benefits at a large temporal scale, and the effects of plain afforestation on stockbreeding and rural economy. The benefits of plain afforestation, correlation coefficiency of agroforestry and production factors are analyzed via stochastic frontier modeling in Huanghuaihai Plain Area of China; elastic coefficient of agroforestry, husbandry, farming, and total output of agricultural sector are calculated through adopting partial differential equation. Some conclusions can be drawn that, plain forests have an important effect on the development of plain agriculture. But shelterbelts and small-scale forests have different effect on the development of agricultural economy. Shelterbelts have negative effect on the industries, but small-scale forest has positive effect. On the whole, contribution of forest resource to value of animal husbandry and gross production value of agriculture is positive, and to the value of farming is negative.

关键词： plain afforestation agricultural development agroforestry plain area of China

Recovery of Bathymetry from Altimeter Data

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Geo-Spatial Information Science 2003年第1期6卷 28-33页

作者： HUANG Motao ZHAI Guojun OUYANG Yongzhong BIAN Shaofeng Tianjin Institute of Hydrographic Surveying and Charting

At present,there exist two methods used to recover the bathymetry from altimeter data,*** deterministic method and the stochastic *** this paper,the principles of the two methods are introduced *** according to the theory of least_square collocation,a modified statistical model for recovering bathymetry from altimeter data is *** new model has been used for computing the ocean depth in the South China Sea from altimeter_derived gravity *** the predicted depths are compared with the ship_borne *** shows that they agree with each other very well.

关键词： altimetry bathymetry least-square collocation