检索结果-南通市图书馆

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

水稻对土壤中镉的吸收及其调控措施

生态学杂志 2004年第3期23卷 120-123页

作者：宗良纲徐晓炎南京农业大学资源环境学院南京210095

对土壤水稻系统镉污染的影响和植物对重金属镉吸收的研究现状进行综述 ,系统阐述土壤受镉污染后水稻生长性状的变化以及水稻吸收的镉在各器官中的分配规律 ,同时分析水分控制。

关键词：土壤-水稻系统镉污染农业管理措施改良剂

Characteristics and origins of primary fluids and noble gases in mantle-derived minerals from the Yishu area,Shandong Province,china

在线全文

学校读者我要写书评

暂无评论

science china Earth sciences 2006年第1期49卷 77-87页

作者： MA Jinlong1,2, TAO Mingxin2,3 & YE Xianren2 1. resources and environmental School, Lanzhou university, Lanzhou 730000, china 2. Key Laboratory of Gas Geochemistry, Institute of Geology and Geophysics, Chinese Academy of sciences, Lanzhou 730000, china 3. college of resources science & Technology, Beijing Normal university, Beijing 100875, china resources and environmental School Lanzhou University Lanzhou China Key Laboratory of Gas Geochemistry Institute of Geology and Geophysics Chinese Academy of Sciences Lanzhou China college of resources science & Technology Beijing Normal University Beijing China

Fluids and noble gases of mantle-derived materials are important tracers forthe mantle information. Compositions of primary fluids and noble gases in mantle-derived mineralsfrom the Yishu area, Shandong Province, china, were tested by the methods of heat-bursting andheat-melting respectively. The fluids are mainly composed of CO_2, CO and H_2, which account forabout 90% of the total, and are similar to the mantle-derived rocks from other areas of easternchina; ratios of ~3He/~4He in almost all samples range from 0.82 Ra to 2.74 Ra, whereas^(40)Ar/^(36)Ar from 299.5 to 758.8. Both ranges are much lower than those of the typical oceanmantle-derived samples (such as MORB) and primarily reflect the influences of the atmosphericcomponents and the radiogenic isotopes. Ratios of C/~3He range from 27.6 x 10~9 to 1050 x 10~9,N_2/Ar from 927 to 56612, and N_2/~3He from 2.5 x 10~9 to 27 x 10~9, similar to those in westernUnited States and New Zealand which belong to the tectonic plate collision regions. The ratios fallin the intersect of mantle-crust-atmosphere in the comprehensive tracer-charts, reflecting theinfluences of the atmosphere and the crusts with organic components. Our results suggest that thecomposition of the primary fluids and the isotopic ratios of the noble gases may either reflect theevolution process of mantle-derived rocks connected with the rise and eruption of magma, or theinfluence of the ancient subduction-plate on the continental mantle of this region.

关键词： noble gases, primary fluids, mantle-derived minerals, Yishu area.

Soil Respiration During a Soy bean-Growing Season

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2006年第2期16卷 192-200页

作者： YANG Lan-Fang CAI Zu-Cong State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences Nanjing 210008 （China）. School of resources and environmental science Hubei University Wuhan 430062 （China） School of environmental Studies China University of Geosciences Wuahn 430074 （China）

Soil respiration induced by soybean cultivation over its entire growing season and the factors influencing soil respiration were investigated to examine the seasonal pattern of soil respiration induced by soybean cultivation, explore soybean growth and photosynthesis on soil respiration, and determine the temperature dependence on soil respiration. Soil respiration in a pot experiment with and without soybean plants was sampled using the static chamber method and measured using gas chromatograph. Air temperature was a dominant factor controlling soil respiration rate in unplanted soil. Additionally, rhizosphere respiration comprised 62% to 98% of the soil respiration rate in the soybean-planted soil varying with the soybean growth stages. Harvesting aerial parts of soybean plant caused an immediate drop in the soil respiration rate at that stage. After harvesting the aerial parts of the soybean plant, a highly significant correlation between soil respiration rate and air temperature was found at the flowering stage （P 〈 0.01）, the pod stage （P 〈 0.01）, and the seed-filling stage （P 〈 0.05）. Thus, rhizosphere respiration during the soybean-growing period not only made a great contribution to soil respiration, but also determined the seasonal variation pattern of the soll respiration rate.

关键词： photosynthesis rhizosphere soil respiration soybean plant temperature effect

A NEW IMPLICIT SCHEME FOR SOLVING 3-D SHALLOW WATER FLOWS

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2009年第6期21卷 790-798页

作者： ZHANG Zhuo SONG Zhi-yao LV Guo-nian State Key Laboratory of Hydrology Water resources and Hydraulic Engineering Ocean College Hohai University Nanjing 210098 China Key Laboratory of Virtual Geographic Environment Ministry of Education Nanjing Normal University Nanjing 210097 China

Based on the improved ADI method, this article proposes an improved implicit finite difference scheme for solving 3-D shallow water flows. The main objective is to design a numerical relation between the horizontal velocity on each layer and the depth-averaged velocity for employing the improved ADI method. With the free surface elevation and the depth-averaged velocity obtained by using essentially 2-D depth-averaged mode, the velocity profiles can be obtained easily and simultaneously. The wind-induced flows, the open channel flows due to the pressure gradient and the tidal flows in coastal waters are simulated, and the results are consistent well with the analytical solution and the field data, which shows that the present implicit scheme is stable and effective, and the established model is practical. Moreover, when only one vertical layer is specified, the present 3-D numerical model is reducea to the 2-D depth-averaged model.

关键词： shallow water equation ADI method wind-induced flow gravity-drived flow tidal flow

Nitrate and Ammonium Leaching in Variable-and Permanent-Charge Paddy Soils

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2010年第2期20卷 209-216页

作者： XIONG Zheng-Qin HUANG Tai-Qing MA Yu-Chun XING Guang-Xi ZHU Zhao-Liang college of resources and environmental sciences Nanjing Agricultural University Nanjing 210095 （China） State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of SciencesNanjing 210008 （China）

A variable-charge （VC） and a permanent-charge paddy soil （PC） were selected to study nitrate-N （NO3^--N） and ammonium-N （NH4^＋-N） leaching with N isotopes for one consecutive year. An irrigation and intermittent drainage pattern was adopted to mimic natural occurrence of rainfall during the upland crop season and drainage management during the flooded rice season. Treatments to each soil type were no-N controls （CK）, ^15N-labeled （NH4）2SO4 （NS）, and milk vetch （NV） applied at a rate equivalent to 238 kg N ha^-1 to unplanted lysimeters, totaling six treatments in triplicates. Results indicated that the soil type dominated N leaching characteristics. In the case of PC, NO3^--N accounted for 78% of the total leached inorganic N; NS was prone to leach three times more than the NV, being 8.2% and 2.4% of added ^15N respectively; and 〉 85% of leached NO3-N came from of the total inorganic N in leachate. Moreover, NH4^＋-N native N in the soil. In the case of VC, NH4^＋-N made up to 92% leaching was detected throughout the whole incubation, and was particularly high during the flooded season. NO3^--N leaching in VC occurred later at a lower rate compared to that in PC. The findings of this study indicate that NO3^--N leaching during the drained season in permanent-charge paddy soils and NH4^＋-N leaching in variable-charge soils deserve more attention for regional environmental control.

关键词： drained/flooded rotations fertilizer-derived nitrate ion movement lysimeter ^15N tracing technique

Soil Organic Carbon Storage in china

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2004年第4期14卷 491-500页

作者： XIEXian-Li SUNBo ZHOUHui-Zhen LIAn-Bo InstituteofSoilscience ChineseAcademyofSciencesNanjing210008（China）. Geographycollege NanjingNormalUniversityNanjing210097（China）

Soil organic carbon (SOC) storage under different types of vegetations in china were estimated using measured data of 2 440 soil profiles to compare SOC density distribution between different estimates, to map the soil organic carbon stocks under different types of vegetation in china, and to analyze the relationships between soil organic carbon stocks and environmental variables using stepwise regression analyses. Soil organic carbon storage in china was estimated at 69.38 Gt (10 15 g). There was a big difference in SOC densities for various vegetation types, with SOC distribution closely related to climatic patterns in general. Stepwise regression analyses of SOC against environmental variables showed that SOC generally increased with increasing precipitation and elevation, while it decreased with increasing ***, the important factor controlling SOC accumulation for forests was elevation, while for temperate steppes mean annual temperature dominated. The more specific the vegetation type used in the regression analysis, the greater was the effect of environmental variables on SOC. However, compared to native vegetation, cultivation activities in the croplands reduced the influence of environmental variables on SOC.

关键词： china environmental factors soil organic carbon storage vegetation

Land Use and Soil Organic Carbon in china’s Village Landscapes

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2010年第1期20卷 1-14页

作者： JIAO Jia-Guo YANG Lin-Zhang WU Jun-Xi WANG Hong-Qing LI Hui-Xin E. C. ELLIS Department of resources and environmental sciences Nanjing Agricultural University Nanjing210095 （China） Institute of Soil science Chinese Academy of Sciences Nanjing 210008 （China） Department of Agronomy and Agroecology China Agricultural University Beijing 100094 （China） Department of Geography ＆ environmental Systems University of Maryland Baltimore County Baltimore 21250 （USA） Center for Louisiana Inland Water Studies University of Louisiana at Lafayette Lafayette Louisiana （USA）

Village landscapes, which integrate small-scMe agriculture with housing, forestry, and a host of other land use practices, cover more than 2 million square kilometers across china. Village lands tend to be managed at very fine spatial scales （≤ 30 m）, with managers both adapting their practices to existing variation in soils and terrain （e.g., fertile plains vs. infertile slopes） and also altering soil fertility and even terrain by terracing, irrigation, fertilizing, and other land use practices. Relationships between fine-scale land management patterns and soil organic carbon （SOC） in the top 30 cm of village soils were studied by sampling soils within fine-scale landscape features using a regionally weighted landscape sampling design across five environmentally distinct sites in china. SOC stocks across china＇s village regions （5 Pg C in the top 30 cm of 2 ×10^6 km^2） represent roughly 4% of the total SOC stocks in global croplands. Although macroclimate varied from temperate to tropical in this study, SOC density did not vary significantly with climate, though it was negatively correlated with regional mean elevation. The highest SOC densities within landscapes were found in agricultural lands, especially paddy, the lowest SOC densities were found in nonproductive lands, and forest lands tended toward moderate SOC densities. Bue to the high SOC densities of agricultural lands and their predominance in village landscapes, most village SOC was found in agricultural land, except in the tropical hilly region, where forestry accounted for about 45% of the SOC stocks. A surprisingly large portion of village SOC was associated with built structures and with the disturbed lands surrounding these structures, ranging from 〉 18% in the North china Plain to about 9% in the tropical hilly region. These results confirmed that local land use practices, combined with local and regional variation in terrain, were associated with most of the SOC variation within and across china＇s

关键词： agriculture land cover change land use change soil carbon sequestration spatial heterogeneity

Temporal variation of suspended sediment load in the Pearl River due to human activities

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2011年第4期26卷 487-497页

作者： Wei ZHANG,Shousheng MU,Yanjing ZHANG,and Kaimin CHEN 1 Assoc.Prof.,State Key Laboratory of Hydrology-Water resources and Hydraulic Engineering,Hohai university, nanjing,210098,china, 2,4 Graduate student,college of Harbor,Coastal and Offshore Engineering,Hohai university,nanjing,210098, china 3 Prof.,china Institute of Water resources and Hydropower Research,Beijing,100038,china Assoc. Prof. State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 China Graduate student College of Harbor Coastal and Offshore Engineering Hohai University Nanjing 210098 China Prof. China Institute of Water Resources and Hydropower Research Beijing 100038 China

Data on sediment flux at three hydrologic stations from the 1950s to 2006 are utilized to study the decadal,annual,and monthly variations in suspended sediment load delivered from the Pearl River to the *** show that variations in sediment flux from three main tributaries,including the West River,the North River and the East River,are spatially *** nearly 90%of the suspended sediment load comes from the West River,its variation has dominated the overall tendency of sediment flux in the entire Pearl *** a significant decreasing trend exists in the annual variation of the total sediment flux,the decadal change can be divided into an increasing phase and a decreasing phase,with the turning point between the two phases in the late *** the 1950s to the 1980s,the average annual river sediment flux increased by 30.43%.However,sediment flux has decreased significantly since the 1990s,with the average sediment flux being 38.60%less in the 2000s than that in the *** current sediment flux is also 52.93%less than its peak in the 1980s. The monthly variation pattern of the suspended sediment load transport to the sea is more interesting. For the West River,all months show a decreasing trend,and for most months the reduction values are ***,for the East River the sediment load shows a decrease trend in the dry season and an increase trend in the wet *** method of regression analysis was used to study the influence of precipitation in the variation on the sediment *** was found that the climate change is not the main driving force behind the variation in suspended sediment *** the 1990s, intensive land use destroyed the vulnerable ecosystem of the upper Pearl River,and speeded up the process of rocky ***,aggravated soil erosion caused an increase in suspended sediment ***,sediment retention within reservoirs had begun to play a dominant role after the massive constru

关键词： Pearl River Sediment flux Human activities Rocky desertification Dam construction

Use of Several Plant Materials and Chemicals to inhibit Soil Urease Activity and Increase Nitrogen Recovery Rate of Urea by Plant

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Pedosphere 2002年第3期12卷 275-282页

作者： XU WEIHONG, WANG ZHENGYIN, JIA ZHONGYUAN, HUANG YUN, YUAN LUJIANG and WANG JUANMEIcollege of resources and environmental science, Southwest agricultural university, Chongqing 400716 (china) college of resources and environmental science Southwest Agricultural University 重庆 400716

Effects of residues of 9 plants, lemon eucalyptus (Eucalyptus citriodoraHook., P_1), robust eucalyptus (E. robusta Smith, P_2), Nepal camphortree (Cinnamomum glanduliferum(Wall.) Nees, P_3), tea (Camellia sinensis (Linn.) O. Ktze. f., P_4), oleander (Nerium indicum Mill,P_5), rape (Brassica campestris L., P_g), Chinese tallow tree (Sapium sebiferum L., P_7), tung(Vernicia fordii (Hemsl.), P_8), and croton (Croton tiglium L., P_9), 7 chemicals, boric acid (C_1),borax (C_2), oxalic acid (C_3), sodium oxalite (C_4), sodium dihydrogen phosphate (C_6), sodiumsilicate (C_7) and sodium citrate (C_8), and a natural organic substance, humic acid (C_5), onurease activity of a neutral purple soil and recovery of urea nitrogen by maize were studied throughincubation and pot experiments. Hydroquinone (HQ) was applied as the reference inhibitor. Afterincubation at 37℃ for 24 h, 7 inhibitors with higher ability to inhibit urease activity wereselected and then incubated for 14 days at 25℃. Results of the incubation experiments showed thatsoil urease activity was greatly inhibited by them, and the inhibition effect followed an order ofP_2>P_4>C_3>C_2>P_3>C_1>HQ>P_1. The 7 selected materials reduced the accumulative amounts of Nreleased from urea and the maximum urease activity by 11.7%～28.4% and 26.7%～39.7%, respectively,and postponed the N release peak by 2～4 days in the incubation period of 14 days under constanttemperature, as compared to the control (no inhibitor). In the pot experiment with the 7 materialsat two levels of addition, low (L) and high (H), the C_1 (H), C_3 (H), C_1 (L), P_4 (L) and C_2 (L)treatments could significantly increase the dry weights of the aboveground parts and the totalbiomass of the maize plants and the apparent recovery rate of urea-N was increased by 6.3%～32.4% ascompared to the control (no hibitor).

关键词： chemicals plant materials recovery rate of fertilizer nitrogen ureaseactivity