3种典型地表风沙流通量廓线研究现状     

马小明  吕萍 《中国沙漠》2016,36(2):302-306

风沙流研究越来越受到人们的重视,其中风沙流通量廓线研究起着重要作用。本文总结了3种典型地表(流沙地表、草方格地表、戈壁地表)风沙流通量廓线研究现状及存在问题。由于研究方法、研究区域及集沙效率的不同,风沙流通量廓线函数有指数函数、对数函数、幂函数、分段函数等多种,同一问题不同函数模拟结果差异可达到3倍,难以应用于实际。根据研究中存在的问题,提出风沙流通量廓线研究发展趋势。  相似文献   

江苏省冬小麦播种期对气候要素变化的响应   总被引：7，自引：2，他引：5  

张佩  高苹  刘彦丽 《气象科学》2011,31(6):763-769

利用江苏省35个气象台站1961- 2009年冬小麦播种期内的气象观测资料,采用数理统计方法,分析了近49 a来冬小麦播种期内各气候要素的变化.结果表明:江苏省冬小麦主要播种期内的日平均气温随着时间的推移逐渐升高,且相关显著,其中淮河以南地区升高速度更快;秋季稳定通过15℃的终日总体呈逐年推迟趋势,尽管部分年际间波动较大;按传统播期播种到越冬的≥0℃有效积温与年序也呈极显著正相关关系.分析沭阳、淮安、盱眙、滨海、赣榆和徐州6个农业气象观测站的冬小麦发育期资料,及当地冬小麦播种至越冬前积温资料.结果表明:各地冬小麦播种至越冬≥0℃有效积温总体上逐年增加.此外,冬小麦播种期内降水量的波动较大,尤其自1990s中期以来,各地降水量呈逐年递减趋势.得出结论:江苏省冬小麦应适时晚播,并应趁墒及时播种.  相似文献   

基于硫酸盐还原菌作用的油菜秆固定床处理模拟含Cr（Ⅵ）废水     

刘畅  陈天虎  周跃飞  金杰 《矿物学报》2011,31(4):742-749

探讨了固定床除Cr工艺以油菜秆为微生物生长的缓释碳源,含SRB的混合微生物和油菜秆对Cr（Ⅵ）的还原和固定的共同作用。动态实验分2阶段开展：初始2周的驯化阶段和梯度增加Cr（Ⅵ）浓度的除Cr实验阶段。除Cr实验中,间歇对固定床出水pH、氧化还原电位、SO42-及硫化物浓度、DOC、Cr（Ⅵ）浓度进行测试,实验结束后对固定床中固体产物进行SEM、EDS和XPS等分析。结果表明,油菜秆固定床处理模拟含Cr（Ⅵ）废水效果明显。当进水Cr（Ⅵ）浓度ρ[Cr（Ⅵ）]〈19.52 mg/L时,出水Cr（Ⅵ）和Cr（Ⅲ）浓度均低于排放标准（0.05 mg/L）;Cr（Ⅵ）被还原为Cr（Ⅲ）,Cr（Ⅲ）以氢氧化物的形式沉淀附着于油菜秆和其它固体物质之上。分析认为,油菜秆在固定床处理模拟含Cr（Ⅵ）废水中所起的作用主要包括3方面（作为微生物生长的缓释碳源;吸附Cr（Ⅵ）,降低其对微生物的毒性;作为Cr（Ⅲ）矿化产物的沉淀附着界面）;Cr（Ⅵ）主要通过SRB的直接作用及H2S的作用被还原为Cr（Ⅲ）;以油菜秆为碳源的固定床处理Cr（Ⅵ）的浓度上限介于15.05～19.52mg/L之间。  相似文献   

低温环境下消化污泥和玉米秸秆强制通风堆肥过程中物理化学和生物学指标的研究     

高孟春  王子超  胡波  王敏  赵从从  杨慧心  田颖  王步英 《中国海洋大学学报(自然科学版)》2011,41(11):13-17

在低温环境下采用强制通风堆肥技术对消化污泥和玉米秸秆进行了堆肥化处理。在环境温度为9～15℃和初始C/N比为19.61情况下,第4天堆体温度达到最高温度60℃,堆体温度保持55℃以上时间为9d。污泥堆肥过程中总有机碳和C/N比下降明显,而NO3--N和重金属含量升高。pH值、电导率、NH4+-N、纤维素酶和脲酶的活性呈先增加后降低的趋势。种子发芽指数在第35天达到84.14%。研究结果表明,消化污泥和玉米秸秆强制通风堆肥在35d达到了腐熟要求。  相似文献   

农谚在河南冬小麦种植及气候适应中的应用     

尹君  苏筠 《地域研究与开发》2011,30(4)

农谚是反映人地关系的地方性知识,研究其在农业生产中的应用及适用性,有助于理解人地关系的变迁及地域特点。收集整理河南冬小麦种植的农谚,归纳总结了冬小麦生育期的农谚时序表。进而利用洛阳、开封、信阳1951—2003年的气象观测数据,分析农谚与气候适应的关系。结果显示,随着气候的变化,农谚中的冬小麦适宜播种期比气象实测的适宜播种期略微早。农谚指出冬小麦越冬期怕冬暖,拔节孕穗期间怕春寒及灌浆需晴暖天气,均与实际观测的气象数据相符合。农谚指出了冬小麦缺水及容易出现旱情的生育阶段,并以此进行旱灾适应。  相似文献   

石津灌区冬小麦水分生产率的尺度效应          下载免费PDF全文

陈皓锐  伍靖伟  黄介生  杨金忠  王少丽 《水科学进展》2013,24(1):49-55

以河北省石津灌区为研究对象,以2007-2009年两季冬小麦生育期为研究时段,基于Hydrus-1D和Modflow模型模拟分析了井渠结合灌溉模式下冬小麦的净入流量水分生产率和净灌溉水分生产率的尺度效应(作物、田间、分干、干渠和灌区尺度)。结果表明:①从作物尺度到灌区尺度,损失水量越来越多,使得净入流量水分生产率和净灌溉水分生产率分别减少了9.49%和16.59%;②由于研究区地下水埋深较大,冬小麦生育期内渗漏补给地下水库的重复利用水量很小,而净灌溉水分生产率因为考虑了这一小部分重复利用水量,比传统的灌溉水分生产率有了小幅提升;③在多年时间尺度上,由于渗漏水量能够全部进入地下水库被重复利用,净入流量水分生产率随尺度增大而增大,而不同空间尺度的净灌溉水分生产率也比冬小麦生育期时间尺度上提高37%~65%。  相似文献   

Wheat straw burning and its associated impacts on Beijing air quality   总被引：18，自引：0，他引：18  

Li LingJun  Wang Ying  Zhang Qiang  Li JinXiang  Yang XiaoGuang  Jin Jun 《中国科学D辑(英文版)》2008,51(3):403-414

Based on MODIS images, large-scale flow field charts and environmental monitoring data, we thor- oughly analyzed the spatial distribution of wheat straw burning in North China, with focus on its envi- ronmental impacts on the air quality of Beijing and pollution transport paths. And we anatomized changes of air quality in Beijing under the impacts of pollution generated by wheat straw burning around. The results indicate that: (1) The North China Plain, a winter-wheat growing area, is the main source of pollutants induced by wheat straw burning in Beijing. The direction of south-west is the dominant heavy pollution transport path. (2) Impacts of wheat straw burning on air quality are mainly manifested by significantly increasing CO concentration. (3) Precursors of O3 generated by wheat straw burning, combining with favorable meteorological conditions, can induce increasing O3 concentration greatly. NO concentration will be greatly increased due to decreasing O3 concentration at night. (4) Atmospheric particles, especially the fine ones, from wheat straw burning exert considerable influ- ence on Beijing air quality. (5) Different contributions of wheat straw burning to pollutants are identified. Ratios of PM10/SO2, CO/SO2, etc., can be applied to indicate pollution extent of wheat straw burning. High ratios of PM10/SO2 and CO/SO2 show that the air quality was heavily impacted by wheat straw burning and these ratios can be employed as indicators of contribution of wheat straw burning to the degradation of Beijing air quality. (6) Randomness of wheat straw burning activities renders random outbreak of air pollution of this type. Regional and extensive wheat straw burning activities can cause serious air pollution event.  相似文献   

Production of Levulinic Acid from Bagasse and Paddy Straw by Liquefaction in the Presence of Hydrochloride Acid     

Lifeng Yan  Naikun Yang  Hao Pang  Bing Liao 《洁净——土壤、空气、水》2008,36(2):158-163

A method of levulinic acid production from bagasse and paddy straw is presented. Biomass waste was mixed with hydrochloride acid and water, and then liquefied at about 200°C in a pressurized reactor. Both the mass of the biomass and the amount of hydrochloride acid were kept as constants, and the effects of temperature, reaction time, and acid concentration on the levulinic acid yield were studied. It was found that the yield of levulinic acid was maximum when the reaction temperature was carried out for 45 min at 220°C using 4.45% concentration of hydrochloride acid, and the maximum yields of levulinic acid were 22.8 and 23.7% for bagasse and paddy straw, respectively. The products were analyzed using NMR, HPLC, and GC/MS.  相似文献   

Modelling blue and green water resources availability in Iran   总被引：7，自引：0，他引：7  

Monireh Faramarzi  Karim C. Abbaspour  Rainer Schulin  Hong Yang 《水文研究》2009,23(3):486-501

Knowledge of the internal renewable water resources of a country is strategic information which is needed for long‐term planning of a nation's water and food security, among many other needs. New modelling tools allow this quantification with high spatial and temporal resolution. In this study we used the program Soil and Water Assessment Tool (SWAT) in combination with the Sequential Uncertainty Fitting program (SUFI‐2) to calibrate and validate a hydrologic model of Iran based on river discharges and wheat yield, taking into consideration dam operations and irrigation practices. Uncertainty analyses were also performed to assess the model performance. The results were quite satisfactory for most of the rivers across the country. We quantified all components of the water balance including blue water flow (water yield plus deep aquifer recharge), green water flow (actual and potential evapotranspiration) and green water storage (soil moisture) at sub‐basin level with monthly time‐steps. The spatially aggregated water resources and simulated yield compared well with the existing data. The study period was 1990–2002 for calibration and 1980–1989 for validation. The results show that irrigation practices have a significant impact on the water balances of the provinces with irrigated agriculture. Concerning the staple food crop in the country, 55% of irrigated wheat and 57% of rain‐fed wheat are produced every year in water‐scarce regions. The vulnerable situation of water resources availability has serious implications for the country's food security, and the looming impact of climate change could only worsen the situation. This study provides a strong basis for further studies concerning the water and food security and the water resources management strategies in the country and a unified approach for the analysis of blue and green water in other arid and semi‐arid countries. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

华北地区不同底墒对冬小麦生长发育及产量影响的研究   总被引：7，自引：0，他引：7       下载免费PDF全文

刘庚山  安顺清  吕厚荃  郭安红 《应用气象学报》2000,(Z1)

1997年 9月至 1 999年 6月在中国气象局固城农业气象试验基地人工控制农田水分试验场进行了冬小麦不同底墒处理的试验 ,结果表明 :底墒显著影响冬小麦的生长发育和产量 ,对冬小麦总生物量、地上和地下生物量的影响在小麦生长后期比前期明显 ;底墒与植株高度、叶面积系数有良好的二次曲线关系 ;底墒显著影响产量构成因素 ,其与籽粒重有相当好的二次曲线关系 ,并据此确定了冬小麦播种时不同深度土层的最佳底墒 :0～ 1 m为 88% ,0～ 2 m为82 % .  相似文献