Evapotranspiration and crop coefficient for a temperate desert steppe ecosystem using eddy covariance in Inner Mongolia,China   总被引：2，自引：0，他引：2  

Feng Zhang  Guangsheng Zhou  Yu Wang  Fulin Yang  Christer Nilsson 《水文研究》2012,26(3):379-386

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亚临界流体萃取高效液相色谱法测定鱼肉中丙酸睾酮残留   总被引：1，自引：0，他引：1  

马勤川  江洁  薛勇  薛长湖  韩玉谦 《中国海洋大学学报(自然科学版)》2012,(9):48-52

采用亚临界1,1,1,2-四氟乙烷(R134a)萃取技术作为样品的前处理技术,建立亚临界流体萃取高效液相色谱法测定鱼肉中丙酸睾酮残留量的新方法。在对添加了丙酸睾酮的罗非鱼肌肉样品亚临界R134a萃取单因素实验的基础上,通过正交实验对萃取条件进行了优化,结果为:萃取压力14MPa,萃取温度23℃,R134a流量1.0L/min(标态),静态萃取30min,动态萃取40min,共溶剂甲醇添加量2mL,收集液为甲醇。收集液经石油醚纯化后,用高效液相色谱检测。在最优条件下,方法回收率大于90%、相对标准偏差(RSD)小于5%。最后,对实际样品进行实际检测,鱼肉冷冻干燥样品中丙酸睾酮的残留量为1.37μg/g。本方法首次利用亚临界R134a萃取作为兽药残留分析样品的前处理技术,萃取压力和萃取温度都比较低,易于大规模推广应用。  相似文献   

土壤、农作物中及家畜体内的微量营养元素   总被引：2，自引：0，他引：2  

Umesh C.Gupta Wu Kening Liang Siyuan 《地学前缘》2008,15(5):110-125

微量营养元素通常富集在表层土壤中,其含量随土层深度递减。尽管土壤中大多数微量元素的含量很高,但只有一小部分能被植物吸收。微量营养元素,也被称为痕迹元素,所需数量微小,但其缺乏会对农作物生产和动物健康造成严重影响。农作物对不同微量营养元素有着不同的反应。芸苔和豆类对Mo和B有较高的响应度,而玉米和其他谷类对Zn和Cu较为敏感。在温润和湿热地区,由于强降雨和强淋溶作用,微量营养元素缺乏较为普遍。土壤pH值是影响微量营养元素对植物有效性的重要因素之一。除Mo以外,微量营养元素的有效性随pH的增加而减小,Mo的有效性随pH的增加而增加。对于大多数植物来说,叶片中的微量营养元素含量高于植物的其他部分。因此,可以用叶片作为样品来测定农作物中微量营养元素的含量。大多数微量营养元素缺乏表现在植物顶部的新叶上,而过量则表现在老叶上。根据Deckers和Steinnes的结论,土壤较为贫瘠的发展中国家与土壤肥沃的欧洲及北美地区相比,微量营养元素缺乏现象较为普遍。许多营养元素缺乏区位于潮湿的热带地区,土壤极度贫瘠、高度风化和/或强淋溶,营养元素十分匮乏。此类其他土壤分部于半干旱及毗邻地区,这些地区的碱性和石灰性土壤条件严重限制了微量营养素对植物的供给。通常,可以满足草料作物生长的Cu、 Fe、Mn、 Zn 、Se含量水平,却不能满足家畜的需要。Se是植物生长所不需要的微量元素,因此草料作物中Se的含量很少。然而,如果动物所食农作物和草料中Se含量偏低,会造成严重的肌肉异常和其他疾病。白肌病是最常见的由于Se缺乏造成的疾病,在牛犊和羔羊中都有发现。本文讨论了与动物需求相关的农作物微量营养元素充足度。  相似文献   

内蒙古通辽市科尔沁区土壤硒地球化学特征     

杨立国  马志超  王鑫 《地质与资源》2019,28(4):383-388

对通辽市科尔沁区土壤与农作物中硒元素地球化学特征及影响因素的系统研究显示,研究区土壤硒含量水平普遍较低,且空间分布不均,仅局部达到足硒水平.硒元素主要富集在表层土壤中,且与有机碳、Al₂O₃、TFe₂O₃、Mn、P等呈正相关关系,表明土壤中有机碳、黏土矿物、铁锰氧化物对硒元素地球化学行为有重要影响.研究区土壤呈碱性至强碱性,富硒农作物并不严格产出在富硒土壤中.因此,开发富硒农产品要综合考虑土壤硒含量、土壤有效态硒含量、农作物硒含量、土壤理化性质及地理景观等因素.  相似文献   

杉木人工林皆伐火烧后土壤呼吸研究   总被引：1，自引：0，他引：1  

刘乐中  杨玉盛  郭剑芬  袁一丁 《福建地理》2008,(1):8-14

通过静态碱吸收法对福建三明27年生杉木人工林皆伐火烧后土壤呼吸进行为期1年多的定位研究．研究发现,林地皆伐火烧后土壤呼吸速率季节变化呈单峰曲线,对照地和皆伐地最大值均出现在6月,火烧地最大值出现在4月和5月之间,3块样地最小值均出现在12月．1年中对照地、皆伐地和火烧地土壤呼吸速率（释放CO2）变化范围分别在86．1～367．9mg m^-2h^-1、62．2～211．7mg m^-2h^-1和42．6～150mg m^-2h^-1之间．用指数模型和双因素模型对土壤呼吸进行拟合显示,温度和湿度是对照地的主要影响因子,但温度和湿度不能很好地解释皆伐地和火烧地土壤呼吸速率的变化．双因素模型中,土壤呼吸温度敏感性因子Q10对照地为2．1,皆伐地和火烧地分别为1．3和1．1,小于已报道范围．  相似文献   

A scheme for regional rice yield estimation using ENVISAT ASAR data   总被引：2，自引：0，他引：2  

ShuangHe Shen  ShenBin Yang  BingBai Li  BingXiang Tan  ZengYuan Li  Thuy Le Toan 《中国科学D辑(英文版)》2009,52(8):1183-1194

Information on rice growing areas and rice production is critical for most rice growing countries to make state and economic policies. However, the areas where rice crop is cultivated are often cloudy and rainy, which entails the use of radar remote sensing data for rice monitoring. In this paper, a practical scheme to integrate multi-temporal and multi-polarization ENVISAT ASAR data into rice crop model for regional rice yield estimation has been presented. To achieve this, rice distribution information should be obtained first by rice mapping method to retrieve rice fields from ASAR images, and then an assimilation method is applied to use the observed multi-temporal rice backscattering coefficients which are grouped for each rice pixel to re-initialize ORYZA2000 to predict rice yield. The assimilation method re-initializes the model with optimal input parameters, allowing a better temporal agreement between the rice backscattering coefficients retrieved from ASAR data and the rice backscattering coefficients simulated by a coupled model, i.e., the combination of ORYZA2000 and a semi-empirical rice backscatter model through LAI. The SCE-UA optimization algorithm is employed to determine the optimal set of input parameters. After the re-initialization, rice yield for each rice pixel is calculated, and the yield map over the area of interest is produced. The scheme was validated over Xinghua study area located in the middle of Jiangsu Province of China by using the data set of an experimental campaign carried out during the 2006 rice season. The result shows that the obtained rice yield map generally overestimates the actual rice production by 13% on average and with a root mean square error of approximately 1133 kg/ha on validation sites, but the tendency of rice growth status and spatial variation of the rice yield are well predicted and highly consistent with the actual production variation. Supported by the ESA-NRSCC Dragon Cooperation Program (), the Project for Jiangsu Graduate in Scientific Research and Innovation (No. CX07B_048z), and the Special Program for Scientific Research in Public Welfare Meteorological Services (No. GYHY200806008)  相似文献   

基于物理模型训练神经网络的作物叶面积指数遥感反演研究   总被引：2，自引：0，他引：2  

刘洋  刘荣高  刘斯亮  刘纪远  陈仲新  王利民  邹金秋 《地球信息科学学报》2010,12(3):426-435

叶面积指数(LAI)是估算作物生长的关键参数。基于物理模型的LAI反演,被认为是当前最为可靠的方法,但其反演复杂。本文提出了将物理模型和神经网络相结合,从地表反射率反演叶面积指数的算法,利用MOD IS地表反射率和4-scale模型反演作物LAI。(1)利用4-scale模型模拟不同LAI与地表反射率的关系,生成训练数据;(2)利用模型模拟的LAI训练神经网络;(3)以MOD IS地表反射率输入训练后的神经网络,反演LAI。估算的LAI与其他LAI产品进行了比较,结果表明,估算的作物LAI和MOD IS及CYCLOPES LAI产品空间和时间分布一致,均方根误差分别为0.4994和0.6558。以2004年衡水的作物LAI地面观测数据进行了直接验证,估算的LAI与研究区地表植被分布一致,但是,三种卫星LAI产品都小于地表测量,故需针对华北平原浓密作物设计模型参数化方案。  相似文献   

Carbon and nitrogen mineralization in soils along a desertification gradient in the semiarid Horqin Sandy Land, Northern China   总被引：1，自引：0，他引：1  

YuQiang Li  HaLin Zhao  TongHui Zhang  YuLin Li  XiaoAn Zuo 《寒旱区科学》2010,2(1):0021-0030

This experiment was conducted in three sites along a desertification gradient in Horqin Sandy Land, Northern China. Soils una-mended and amended with five types of plant residue in a wide range of C:N ratios from 9.9 to 82.2 were incubated for 70 days, during which C and N mineralization were measured. Along the desertification gradient from fixed sand dune to semifixed, and mobile sand dune: cumulative CO2-C produced from the unamended soils was 231.6, 193.3 and 61.9 μg/g, respectively, while net inorganic N was 22.9, 17.6 and 0.9 mg/kg. Soils amended with residues produced more CO2-C than the unamended soils across all sites. During the first 10 days, C mineralization rate of residue-amended soils decreased with the increase of C:N ratio at each site. However, the mineralization rates were poorly correlated with the C:N ratio in subsequent stage of incubation. Soils of mobile sand dune amended with higher C:N ratio (more than 32) residues produced less CO2-C than that of fixed and semifixed sand dune. NO3--N was the predominant form of inorganic N during the mineralization process in sandy soils. Carbon-to-nitrogen ratio (C:N) can be regarded as a predictor of the speed of N mineralization in sandy soil. The more C. microphylla residue with the lowest C:N ratio (9.9) added in soils, the more net inorganic N released. Our results suggest that C. microphylla residue when added to soil would potentially provide short-term plant available N and improve the soil quality in sandy land. The desertification process postponed the release of inorganic N from plant residues.  相似文献   

燃煤电厂脱硫工艺及工艺选择要素探讨     

常艳君 《气象与环境学报》2007,23(5):57-61

针对我国燃煤电厂SO2排放及污染现状和目前国内外燃煤电厂普遍采用的几种典型脱硫工艺的比较,对脱硫工艺及其工艺选择的主要影响因素进行了概述。根据脱硫工艺的选择要素,从应用条件、技术、经济和环境等方面进行分析,并结合我国的实际情况,提出了燃煤电厂脱硫工艺的技术路线。  相似文献   

Design of farmland gis for precision agriculture   总被引：1，自引：1，他引：0  

ANKai XIEGao-di LENGYung-fa XIAOYu 《中国地理科学(英文版)》2003,13(1):20-24

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