阿尔泰南缘麦兹泥盆纪火山-沉积盆地成矿特点及其铅锌、铁、金找矿潜力分析   总被引：8，自引：1，他引：7  

郭正林  郭旭吉  王书来  秦克章 《矿床地质》2007,26(1):128-138

麦兹盆地位于西伯利亚板块南缘阿尔泰陆缘活动带中,是一个重要的铅、锌、铁矿化集中区,其中著名的有蒙库大型铁矿床、可可塔勒大型铅锌矿床,是阿尔泰南缘多金属成矿带中最重要的成矿盆地之一。盆地内矿床、矿点多为火山喷流热水沉积成因,层控特征明显,具有规模大、形态规则、厚度及有用组分稳定等特点。铁矿成矿与早泥盆世早期细碧角斑质火山作用相伴,而铅锌成矿则与早泥盆世晚期长英质火山喷流沉积作用相伴。通过对麦兹盆地成矿地质特征和典型矿床中矿体分布变化规律的研究,认为北西向同生断裂、火山沉积洼地、火山喷发中心(火山机构)共同控制铅锌矿的产出,矿体还受到后期褶皱、变质作用的改造。根据有利层位、火山岩相、喷流沉积岩、热液蚀变、矿化组合、铁帽、控矿构造和地球化学异常等综合找矿评价标志,分析了可可塔勒矿区深部、什根特、铁热克萨依、H-48号异常的铅锌找矿潜力,并探讨了盆地内铁、金的找矿潜力,指出了进一步找矿的方向与有利地段。  相似文献   

The impact of weather variations on maize yields and household income: Income diversification as adaptation in rural China     

《Global Environmental Change》2017

Climate change is threatening global food production and could potentially exacerbate food insecurity in many parts of the world. China is the second largest maize producer. Variations in maize yields in China are likely to have major implications for food security in the world. Based on longitudinal data of 4861 households collected annually between 2004 and 2010, we assess the impact of weather variations on maize yields in the two main producing regions in China, the Northern spring maize zone and the Yellow-Huai Valley summer maize zone. We also explore the role of adaptation, by estimating the response of Chinese farmers in both regions, in particular in terms of income diversification. With the use of household and time fixed effects, our estimates relate within-household variations in household outcomes (maize yields, net income, land and input use) to within-location variations in weather conditions. Temperature, drought, wet conditions, and precipitations have detrimental effects on maize yields in the two maize zones. The impact is stronger in the Northern spring maize zone where one standard deviation in temperature and drought conditions decreases maize yields by 1.4% and 2.5%, respectively. Nonetheless, such impact does not seem to translate into a significant fall in total net income. Adaptation seems to be key in explaining such a contrast in the Northern spring maize zone where the largest impact is estimated. On the contrary, we find a lower impact in the other region, the Yellow-Huai Valley summer maize zone but such impact is likely to intensify. The lack of adaptation observed in that region results into detrimental impacts on net farm and total income. Enhancing adaptative behaviors among Chinese farmers even further is likely to be key to future food security in China and in the rest of the world.  相似文献   

基于水热因子的玉米物候模拟   总被引：3，自引：1，他引：2       下载免费PDF全文

李荣平  周广胜  刘景利  史奎桥  梁涛 《气象与环境学报》2009,25(3):19-23

对锦州14 a玉米各生育期特征及其与气候因子的关系分析表明：同品种玉米的物候期相近,变化在2 d左右,而吐丝期到成熟期所需天数变化较大,为6 d或以上;玉米各生育期的影响因子不同,气温与湿度对玉米出苗期、三叶期和七叶期的影响显著,播种期到七叶期的积温占整个生育期积温的20%,并与同期的空气湿度累积量显著二次曲线相关（R 2=0.91）。积温与空气湿度累积可较好地模拟玉米播种期至七叶期和玉米的总生育期。  相似文献   

富裕县农田土壤湿度变化及其对玉米发育期和产量的影响   总被引：1，自引：0，他引：1  

闫平  季生太  孙彦坤  姜丽霞  王秋京  吕佳佳  王萍 《气象与环境学报》2020,36(4):74-82

本文旨在分析黑龙江省富裕县农田土壤相对湿度对玉米发育期和产量的影响,以期为松嫩平原西部玉米生产提供科学参考。以黑龙江省富裕县为研究区域,利用1982—2017年土壤相对湿度资料、1995—2017年玉米发育期资料、玉米产量资料,采用对比分析、相关分析、Mann-Kendall突变检验法,分析土壤相对湿度变化特征,研究土壤相对湿度对玉米发育期和产量的影响。结果表明：富裕县近36 a土壤相对湿度呈增加—减小—增加的趋势。播种期—出苗期、拔节期—抽雄期、乳熟期—成熟期土壤干旱平均每4—6 a一遇,抽雄期—乳熟期每2—3 a一遇,出苗期—拔节期土壤基本无旱。各发育期土壤相对湿度减小的突变年在1987年前后,增加的突变年在2013年前后。20世纪80年代土壤较适宜,干旱轻,90年代土壤相对湿度迅速下降,干旱最重,之后随着年代的推移土壤干旱逐渐减轻。玉米主要发育期中播种期—出苗期、出苗期—拔节期土壤干旱对产量影响较小,拔节期—成熟期是土壤干旱影响产量的主要时期。  相似文献   

不同物候模型对作物发育期模拟的对比分析   总被引：1，自引：0，他引：1       下载免费PDF全文

李荣平  周广胜  王笑影  史奎桥 《气象与环境学报》2012,28(3):25-30

作物发育期预报在农业气象业务中具有重要意义。通过比较4种作物发育期模型的模拟效果,为中国东北地区作物发育期预报提供参考。基于东北地区玉米、水稻和大豆的发育期观测数据及其对应的气象资料,利用模拟退火算法估算了4个发育期模型的参数值,并对模型进行内外部验证。结果表明：在参数本地化过程中,高亮之模型和沈国权模型的效果较好,均方根误差平均分别为3.31d和3.72d。在模型验证过程中,沈国权模型的模拟效果较好,均方根误差平均为5.22d,因此,相对而言,沈国权模型对作物发育期模拟效果较好。  相似文献   

Assessing crop yield benefits from in situ rainwater harvesting through contour ridges in semi-arid Zimbabwe     

《Physics and Chemistry of the Earth》2013

Rainwater harvesting through modified contour ridges known as dead level contours has been practiced in Zimbabwe in the last two decades. Studies have shown marginal soil moisture retention benefits for using this technique while results on crop yield benefits are lacking. This paper presents results from a field study for assessing the impact of dead level contours on soil moisture and crop yield carried out from 2009 to 2011 within the Limpopo River Basin. The experiments were carried out on two study sites; one containing silt loam soil and another containing sandy soil. Three treatments constituting dead level contoured plots, non-contoured plots and plots with the traditional graded contours were used on each site. All the three treatments were planted with a maize crop and managed using conventional farming methods. Planting, weeding and fertiliser application in the three treatments were done at the same time. Crop monitoring was carried out on sub plots measuring 4 m by 4 m established in every treatment. The development of the crop was monitored until harvesting time with data on plant height, leaf moisture and crop yield being collected. An analysis of the data shows that in the site with silt loam soil more soil moisture accumulated after heavy rainfall in dead level contour plots compared to the control (no contours) and graded contour plots (P < 0.05). However the maize crop experienced an insignificantly (P > 0.05) higher yield in the dead level contoured treatment compared to the non-contoured treatment while a significantly (P < 0.05) higher yield was obtained in the dead level contoured treatment when compared with a graded contoured treatment. Different results were obtained from the site with sandy soil where there was no significant difference in soil moisture after a high rainfall event of 60 mm/day between dead level contour plots compared to the control and graded contour plots. The yield from the dead level contoured treatment and that from the graded contoured treatment were comparable and both not significantly (P > 0.05) higher than that from the non-contoured treatment. This suggests that adopting dead level contours as an in situ rainwater harvesting technique results in crop yield benefits in fields with soil type conditions that enable runoff generation but is not likely to have benefit in soils with low runoff generation.  相似文献   

1980-2009年黑龙江省玉米种植期低温冷害环流形势     

张雪梅  陈莉  朱海霞  兰博文  王冀 《气象与环境学报》2013,29(3):48-51

利用1980-2009年5-9月黑龙江省24个气象站逐月平均气温资料、玉米品种及发育期资料和NCAR/NCEP再分析逐月500 hPa高度格点资料,分析玉米种植期间低温冷害的历史特征和低温冷害期间各类型500 hPa环流月平均距平合成场特征。结果表明：玉米种植期间,8-9月份最容易出现冷害,其余的排序是6、7月和5月。玉米种植期间,北部出现低温冷害的次数最多,东部、中部、西部次之,南部最少;南部出现低温冷害时,北部、中部和西部均出现了低温冷害,东部大部分出现了低温冷害。发生玉米低温冷害的月份,低温冷害发生区域月平均500 hPa高度距平场大多为负距平;玉米低温冷害发生区域对应的500 hPa高度距平值明显具有严重区域小于一般区域小于轻微区域的特征。  相似文献   

秸秆覆盖下的夏玉米蒸散、水分利用效率和作物系数的变化   总被引：29，自引：0，他引：29  

张喜英  陈素英  裴冬  刘孟雨 《地理科学进展》2002,21(6):583-592

农业用水占华北水资源的70%以上,提高农业用水的效率对华北水资源安全具有重要意义。在节水农业研究中,利用农艺节水提高农田水分利用效率是节水农业的重要组成部分,其中减少农田无效棵间蒸发耗水和优化供水制度是主要的农艺节水措施。夏玉米是华北太行山山前平原的主要作物之一,一般在冬小麦收获前的5～7天套种在其中,以延长夏玉米的生育期。随着联合收割机的广泛应用,冬小麦收获后的秸秆直接覆盖夏玉米,对夏玉米的农田蒸散特别是苗期的蒸散产生影响;夏玉米生长在6～9月的雨季,一般年份降水能够满足夏玉米的需水要求,但夏季降水的分布变异较大,再加上近6年来的夏季干旱,使灌水对夏玉米的高产至关重要。为了提高夏玉米的农田水分利用效率,本研究的目的是建立秸秆覆盖下的夏玉米优化供水制度和研究秸秆覆盖对减少棵间无效耗水的影响及秸秆覆盖下的夏玉米作物系数的变化,为制定秸秆覆盖下的夏玉米优化供水制度提供依据。2年的实验结果显示,秸秆覆盖下的夏玉米产量在8000kg/ha,总蒸散量在390mm,水分利用效率在2.2kg/m3。干旱年份,夏玉米在灌四水的条件下产量最高,再增加灌水量,产量减少。水分利用效率随着灌水量的增加有所递减。  相似文献   

Effects of Lime‐Based Waste Materials on Immobilization and Phytoavailability of Cadmium and Lead in Contaminated Soil     

Jung Eun Lim  Mahtab Ahmad  Sang Soo Lee  Christopher L. Shope  Yohey Hashimoto  Kwon‐Rae Kim  Adel R. A. Usman  Jae E. Yang  Yong Sik Ok 《洁净——土壤、空气、水》2013,41(12):1235-1241

Low cost lime‐based waste materials have recently been used to immobilize metals in contaminated soils. This study was conducted to evaluate the effects of oyster shells and eggshells as lime‐based waste materials on immobilization of cadmium (Cd) and lead (Pb) in contaminated soil, as well as their effects on metal availability to maize plants (Zea mays L.). Oyster shells and eggshells were applied to soils at 1 and 5% w/w, after which they were subject to 420 days of incubation. The toxicity characteristic leaching procedure (TCLP) test was employed to determine the mobility of Cd and Pb in soils. The results showed that the addition of waste materials effectively reduced the metal mobility as indicated by the decrease in the concentration of TCLP‐extractable Cd and Pb, and this was mainly due to significant increases in soil pH (from 6.74 in untreated soil to 7.85–8.13 in treated soil). A sequential extraction indicated that the addition of such alkaline wastes induced a significant decline in the concentration of Cd in the exchangeable fraction (from 23.64% in untreated soil to 1.90–3.81% in treated soil), but it increased the concentration of Cd in the carbonate fraction (from 19.59% in untreated soil to 36.66–46.36% in treated soil). In the case of Pb, the exchangeable fraction was also reduced (from 0.67% in untreated soil to 0.00–0.01% in treated soil), and the fraction of Pb bound to carbonate was slightly increased (from 16.61% in untreated soil to 16.41–18.25% in treated soil). Phytoavailability tests indicated that the metal concentrations in the shoots of maize plant were reduced by 63.39–77.29% for Cd and by 47.34–75.95% for Pb in the amended soils, with no significant differences being observed for the amendment types and the application rates. Overall, these results indicate that oyster shells and eggshells can be used as low cost lime‐based amendments for immobilizing Cd and Pb in contaminated soils.  相似文献   

Modelling analysis of water-use efficiency of maize in Heihe River Basin     

《Physics and Chemistry of the Earth》2016

Water, as an important resource in ecosystem, greatly influence human life. Increasing water use efficiency will save water resources, thus will lead to better ecosystem. Agricultural water resources are important production materials that will impinge the long-term agriculture development potential, while water use efficiency (WUE) is a key factor closely linked to agricultural production. In this study targeted at Heihe Agriculture Zone, we used a stochastic frontier production function to study agricultural production efficiency and WUE.In particular, the effects of planting areas on farmers' WUE were investigated. The result show current farmers' WUE of Maize is 0.67 on average, which still can be improved largely. The farmers' planting scales largely affect WUE of Maize. The farmers with planting scales of 0–0.3 ha and over 1.3 ha paid high attention to WUE. The optimal planting scale of water use efficiency of maize is around 3.3 ha. This study provides a scientific basis for the water resource use in arid and semiarid regions  相似文献