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复杂地形任意天气情形下太阳直接辐射量模拟 总被引：2，自引：1，他引：1
以太阳辐射传输参数化模型为基础,结合MODIS影像两次白天的云产品和水汽产品及DEM,构建了复杂地形任意天气情形下每日太阳直接辐射量模型。选取代表不同气候类型与地形起伏状况的3个典型站点(拉萨、北京、额济纳旗),以2007年每日实测值对模拟结果进行了验证,其相关系数分别为0.77、0.77和0.85。研究表明:有云天气下,云是影响地表太阳直接辐射数量和空间分布的主要因子;模型对时间步长不敏感。引起误差的原因主要是MODIS云产品的时空分辨率较低以及云的3D效应导致模拟的困难,对地形起伏较大地区,小比例尺的DEM也会导致较大的误差,同时实测值与模拟值的空间尺度不匹配也引起了一定误差。 相似文献
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本次研究在贵州省耕地质量地球化学调查评价的基础上，结合本单位承担的调查项目，优选出硒资源潜力丰富的六枝特区耕地为研究对象，根据研究区富硒土壤划分根据《土地质量地球化学评价规范》(DZ/T 0295-2016)和贵州省富硒土壤评价分级标准(试行)”，采用多种地球化学分析测试方法对研究区进行了硒含量及分布特征评价，结合五种农作物硒含量分析结果，初步查明了研究区内基岩和各类土壤硒背景值，根据硒含量初步划定了区内不同富硒区范围，为富硒土壤资源的开发利用提供了参考依据。结果表明:研究区土壤硒含量值处于004753 mg/kg之间，平均含量054 mg/kg，总体接近背景值。研究区基岩硒含量值有一定差异，表现为二叠系上统含煤岩系中硒含量最高，平均值098 mg/kg，高于周缘耕地土壤硒含量，指示出该地层可能提供部分硒；侏罗系粘土岩分布区中硒含量最低，平均值020 mg/kg，低于区域耕地土壤硒含量。综合解读分析测试数据，初步圈定区内富硒土壤面积约7236万亩，占全区耕地面积的7379%，其中可开发面积约6729万亩，具有发展富硒产业的良好基础，本次研究对于调整区内富硒农作物种植结构、发展特优农作物种植，增加就业和脱贫攻坚战略目标具有重大意义。 相似文献
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东莞市农田土壤和蔬菜重金属含量分析(英文) 总被引：7，自引：1，他引：6
A total of 118 of agricultural soil and 43 of vegetable samples were collected from Dongguan City,Guangdong,China. The spatial distribution,sources,accumulation charac-teristics and potential risk of heavy metals in the agricultural soils and vegetables were de-picted in details by three different approaches,including total contents of eight metal ele-ments in soils and vegetables,GIS maps and multivariate analysis of heavy metals in soils in the study. The results show that there are higher accumulation of heavy metals such as Cu,Zn,Ni,Pb,Cd and Hg in agricultural soils,and the contents of Pb (65.38 mg kg-1) and Hg (0.24 mg kg-1) are 1.82 and 2.82 times of the background contents of the corresponding heavy metals in soils of Guangdong Province,respectively. There are about 3.4% of Cu,5.9% of Ni,1.7% of Cd and 28% of Hg in all collected soil samples from all investigated sites which have overran the contents for heavy metals of the China Environmental Quality Standard for Soils (GB15618-1995,Grade Ⅱ ). The pollution characteristics of multi-metals in soils are mainly reflected by Hg. There are different sources to eight metal elements in soils,Cu,Zn,Ni,Cr and As are predominantly derived from parent materials,and Pb,Hg and Cd are affected by anthropogenic activities. The spatial distribution shows that the Cu,Zn,Ni,Cr,Pb,As and Hg contents of agricultural soils are high in the west and low in the east,and Cd contents are high in the northwest,southeast and low in the southwest in Dongguan. The ratios of vegetable samples which Ni,Pb and As concentrations higher than the Maximum Levels of Con-taminants in Foods (GB2762-2005) are 4.7%,16.3% and 48.8%,respectively. The order of bio-concentration factors (BCF) of heavy metals in vegetables is Cd Zn Cu As Ni Hg Cr Pb. It is necessary to focus on potential risk of heavy metals for food safety and hu-man's health from agricultural soils and vegetables in Dongguan City,Guangdong Province. 相似文献
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