黄土旱塬麦田生态系统物质平衡及评价

根据长武试区 1986～ 1995年的统计资料并结合田间试验 ,对黄土旱塬麦田生态系统的主要物质 (氮、磷、钾 )循环及平衡特征进行了较为系统的分析。结果表明 ,农田中养分的流动量大 ,流通途径少 ,养分循环的开放性大 ,外循环规模大 ,内循环率小 ;系统养分平衡中 N基本保持收支平衡 ,K2 O入不敷出 ,P2 O5 输入大于输出 ;养分输入中 ,人工投入的化肥与有机肥是养分的主要来源 ,输出中 N主要集中于籽粒 ,K2 O主要集中于秸秆 ,P2 O5 主要残留于土壤中。指出在农业生产中 ,应采用秸秆还田以增加钾的投入 ,同时要增加氮肥投入尤其是有机肥的投入 ,而磷应以提高其有效性为主。

黄土高原地区土壤可蚀性及其应用研究

通过回顾已有的成果 ,分析评价了我国土壤可蚀性研究的进展及存在的问题 ,提出我国土壤可蚀性研究中的标准小区定义。运用野外观测资料 ,研究计算了黄土高原地区土壤可蚀性指标值。结果表明 ,陕北和晋西北一带黄土可蚀性 K值变化于 0 .3～ 0 .7之间 ,并且有以陕西子洲、绥德一带为最大 ,以此为中心 ,向南、向北和向东都减少的变化趋势。

基于GIS的小流域坡耕地调查方法探讨

坡耕地研究是水土流失治理及水土保持规划的核心内容 ,GIS的发展及其在多领域的成功应用为坡耕地研究提供了新的技术手段。用矢量基础图件叠加来获取单元图斑的方法是GIS的基本功能 ,但叠加多边形的不确定性成为影响GIS数据质量的灾难性因素。以MapGIS作为基础平台 ,以DOM作为控制底图更新信息 ,采取矢栅叠加的方法获得单元图斑 ,用操作属性表获取专题属性 ,进行小流域坡耕地快速调查的研究 ,展示了矢栅叠加方法在信息复合过程中的显著优势。

基于RS和GIS的纸坊沟流域土地利用动态监测及分析

以纸坊沟流域多年土地利用监测数据为基础 ,对其结果进行分析和讨论。结果表明 ,到 1 999年底 ,农业、林业、牧业用地面积比例分别为 1 6.9%、34.0 %、36.8%。人均基本农田由 1 975年 0 .0 5 4 7hm2 ,增到 1 999年的 0 .2 0 33hm2 ,坡耕地大幅度减少 ,粮食平均产量也由 1 975年的 5 61 kg/hm2 ,增到 1 999年的 2 31 9kg/hm2 ,流域林草有效覆盖率达到 5 7.4% ,植物种类和数量得到增加。走上了农林牧协调发展和生态环境良性循环的轨道

黄土旱塬麦田生态系统能流特征及评价

根据长武试区 1 986年～ 1 995年连续 1 0年的统计资料并结合田间试验 ,对黄土旱塬典型农田生态系统——冬小麦农田系统能量的投入产出、流向、流量与转化效率进行了较为系统的研究。结果表明 ,能量平衡中人工辅助能的投入逐渐增加 ,化肥能投入比例逐渐超过有机肥能 ;该区农业已发展到无机—有机复合阶段 ,农业生产中机械化程度有所提高。通过统计分析 ,得出提高无机能的投入比例可提高能量的产投比 ,增加化肥能投入水平则可提高能量的总产出 ,指出应在机械化条件下实行秸秆还田和多途径增加有机肥投入 ,调整能量投入结构 ,提高能量转化效率 ,提高光能利用率

黄土区渭北旱塬苹果基地对区域水循环的影响

通过对苹果地、农田和其他塬面主要土地利用方式的比较研究 ,发现苹果地土壤入渗速率大、降雨产流率低和存在生物利用型土壤干层。这些水文学性质将增强土壤 -植物 -大气间垂直水分交换 ,削弱降雨转化为地表径流和地下水的比例 ,最终影响区域地表和地下水资源的数量。另外土壤干层的出现还削弱了土壤水库对年际和季节性干旱的调节作用 ,导致苹果产量随降雨量的自然变化呈现较大波动

半湿润区农田生态系统氮肥对不同基因型冬小麦产量构成的影响

施N对“NR9405”、“9430”、“偃师9号”、“小偃6号”、“陕229”、“西农2208”、“矮丰3号”和“商188”这8种不同基因型冬小麦产量构成影响的田间试验结果表明,单株分蘖成穗数、单位面积粒数和单位面积株数的差异同时受基因和N素营养水平控制。“矮丰3号”和“小偃6号”单株分蘖成穗数最多,分别为2.00分蘖穗/株和1.72分蘖穗/株,“9430”最少,为0.85分蘖穗/株。从不同基因型看,施N比不施N处理增加0.74穗/株,每穗粒数在不同基因型间存在极显著差异,以“西农2208”最多,为36.73粒/穗,“NR9405”最少,为24.35粒/穗,施N对每穗粒数无显著影响。单位面积株数主要受施N影响,基因型间差异相对较小。基因型和施N同时显著影响单位面积粒数和千粒重,但基因型对千粒重的影响程度大于N肥。从2个施N水平看,单位面积籽粒产量存在显著差异,“矮丰3号”、“西农2208”、“偃师9号”、“陕229”、“9430”、“小偃6号”、“商188”和“NR9405”依次减小,“矮丰3号”为435g/m2,“NR9405”为316g/m2,相差119g/m2。施N可极显著增加单位面积籽粒产量,不同基因...

施氮与基因型对半湿润区冬小麦灌浆期籽粒氮、磷累积的影响

在年均降水量632mm的黄土高原南部半湿润区红油土上以“9430”、“小偃6号”和“商188”为供试材料,研究了不施N和施N(90kg/hm2)条件下不同基因型冬小麦灌浆期间籽粒中N、P累积特性。结果表明,不同基因型冬小麦灌浆期间籽粒含N量呈现出“高-低-高”的时间变化趋势,而籽粒含P量基本呈直线下降趋势。不同基因型小麦籽粒最终含N量的高低与灌浆进程中籽粒含N量的高低一致,“小偃6号”籽粒含N量始终高于“商188”和“9430”。在整个灌浆期间,籽粒中N累积速率显著高于P累积速率,灌浆末期表现更为明显。籽粒N的活跃累积期与千粒重呈显著正相关,提高籽粒中N累积速率有利于增加籽粒蛋白质含量。基因型是控制籽粒中N活跃累积期和N活跃平均累积速率的主要因子,而基因型对籽粒P活跃累积期和平均累积P速率无显著影响。施N虽然对灌浆期间籽粒N、P累积参数无显著影响,但在一定程度上可以提高灌浆进程中籽粒含N量,对最终籽粒N累积具有一定的促进作用。

Impacts of LUCC processes on potential land productivity in China in the 1990s

Using meteorological data and RS dynamic land-use observation data set, the potential land productivity that is limited by solar radiation and temperature is estimated and the impacts of recent LUCC processes on it are analyzed in this paper. The results show that the influence of LUCC processes on potential land productivity change has extensive and unbalanced characteristics. It generally reduces the productivity in South China and increases it in North China, and the overall effect is increasing the total productivity by 26.22 million tons. The farmland reclamation and original farmlands losses are the primary causes that led potential land productivity to change. The reclamation mostly distributed in arable-pasture and arable-forest transitional zones and oasises in northwestern China has made total productivity increase by 83.35 million tons, accounting for 3.50% of the overall output. The losses of original farmlands driven by built-up areas invading and occupying arable land are mostly distributed in the regions which have rapid economic development, e.g. Huang-Huai-Hai plain, Yangtze River delta, Zhujiang delta, central part of Gansu, southeast coastal region, southeast of Sichuan Basin and Urumqi-Shihezi. It has led the total productivity to decrease 57.13 million tons, which is 2.40% of the overall output.

Industrial development and land use/cover change and their effects on local environment: a case study of Changshu in eastern coastal China

The interactions among industrial development, land use/cover change (LUCC), and environmental effects in Changshu in the eastern coastal China were analyzed using high-resolution Landsat TM data in 1990, 1995, 2000, and 2006, socio-economic data and water environmental quality monitoring data from research institutes and governmental departments. Three phases of industrial development in Changshu were examined (i.e., the three periods of 1990 to 1995, 1995 to 2000, and 2000 to 2006). Besides industrial development and rapid urbanization, land use/cover in Changshu had changed drastically from 1990 to 2006. This change was characterized by major replacements of farmland by urban and rural settlements, artificial ponds, forested and constructed land. Industrialization, urbanization, agricultural structure adjustment, and rural housing construction were the major socio-economic driving forces of LUCC in Changshu. In addition, the annual value of ecosystem services in Changshu decreased slightly during 1990-2000, but increased significantly during 2000-2006. Nevertheless, the local environmental quality in Changshu, especially in rural areas, has not yet been improved significantly. Thus, this paper suggests an increased attention to fully realize the role of land supply in adjustment of environment-friendly industrial structure and urban-rural spatial restructuring, and translating the land management and environmental protection policies into an optimized industrial distribution and land-use pattern.

Land use and water quality response in the northern region of Changxing County

In this paper, taking the northern region of Changxing County for example, with ammonia nitrogen as a pollution assessment index, we used an improved export coefficient method for estimate polluting load of non-point source pollution (NSP) and the social pollution survey data in the study area to estimate point source pollution. By comparing the total pollution output and the national surface water environmental quality standards find that the whole study area achieves the second water quality standard. However, Jiapu Township exceeds the water quality standards seriously because of the superfluous point source pollution. The water quality of other Townships is good. Further analysis showed that different types of land use and proportions in the northern region of Changxing County have a significant impact on the non-point source pollution, the general law is farmland contributes the largest share of the non-point source pollution output, followed by residential area and bare land, besides, with the increase in the proportion of forest and the decrease of farmland and residential area, the non-point source pollution reduces gradually. © 2010 IEEE.

Direct electrochemistry of horseradish peroxidase immobilized in calcium carbonate microsphere doped with phospholipids

Protein electrochemistry affords a direct method to study the biological electron transfer processes. However, supplying a biocompatible environment to maintain the native state of protein is all-important and challengeable. Here, we chose vaterite, one of the crystalline polymorphs of calcium carbonate, with highly porous nature and large specific surface area, which was doped with phospholipids, as the matrix to immobilize horseradish peroxidase (HRP). The integrity of HRP was kept during the simple immobilization procedure. By virtue of this organic/inorganic complex matrix, the direct electrochemistry of HRP was realized, and the activity of HRP for catalyzing reduction of O-2 and H2O2 was preserved.

DNA-Templated Gold Nanoparticles Formation

The interaction between HAuCl4 and DNA has enabled creation of DNA-templated gold nanoparticles without formation of large nanoparticles. It was found that spheral DNA-HAuCl4 hybrid of 8.7 nm in diameter, flower-like DNA-HAuCl4 hybrid, nanoparticles chains and nanoparticles network of DNA-HAuCl4 hybrid could be obtained by varying the reaction conditions, including DNA concentration and reaction temperature. The intermediate product was investigated by shortening the reaction time of DNA and HAuCl4, and the obtained nanoparticles preserved a small DNA segment, which indicated that the reaction between DNA and HAuCl4 had a process.

Confined intra-molecular clustering in orientated polyethylene after annealing

Deuterated polyethylene tracer molecules with small amount of branches (12 C2H5- branches per 1000 backbone carbon atoms) were blended with a hydrogenated polyethylene matrix to form a homogenous mixture. The conformational evolution of the deuterated chains in a stretched semi-cry stall me film was observed via online small angle neutron scattering measurements during annealing at high temperatures close to the melting point. Because the sample was annealed at a temperature closely below its melting point, the crystalline lamellae were only partially molten and the system could not fully relax. The global chain dimensions were preserved during annealing. Recrystallization of released polymeric chain segments allows for local phase separation thus driving the deuterated chain segments into the confining interlamellar amorphous layers giving rise to an interesting intra-molecular clustering effect of the long deuterated chain. This clustering is deduced from characteristic small angle neutron scattering patterns. The confined phase separation has its origin in primarily the small amount of the branches on the deuterated polymers which impede the crystallization of the deuterated chain segments.

Structural features of the L-argininamide-binding DNA aptamer studied with ESI-FTMS

The 24-mer DNA aptamer of Harada and Frankel ( Harada, K.; Frankel, A. D. EMBO J. 1995, 14, 5798-5811) that binds L-argininamide (L-Arm) was studied by electrospray ionization Fourier transform mass spectrometry (ESI-FTMS). This DNA folds into a stem and loop such that the loop is able to engulf L-Arm. As controls, two derivatives of the same base composition, one with the same stem but a scrambled loop and the other with no ability to form a secondary structure, were studied. The two DNAs that could fold into stem-loop structures showed a more negatively charged distribution of ions than the linear control. This tendency was preserved in the presence of ligand; complexes expected to have more secondary structure had ions with more negative charges. Distinct species corresponding to no, one, and two bound L-Arm molecules were observed for each DNA. The fractional peak intensities were fit to a straightforward binding model and binding constants were obtained. Thus, ESI-FTMS can provide both qualitative and quantitative data regarding the structure of DNA and its interactions with noncovalent ligands.