共查询到20条相似文献，搜索用时 515 毫秒
1.
This paper presents an algorithm and its numerical realization for a simulation model of migration of radiocesium in a certain
volume of soil, including non-uniform contamination and pronounced inclination of the soil surface. The model can also be
used to predict the redistribution of soil toxicants. 相似文献
2.
温室环境温度预测自适应机理模型参数在线识别方法 总被引：5，自引：3，他引：2
温室小气候模型具有非线性、强干扰、时变等特性,常用的线性化模型或离线辨识模型无法有效预测温室环境动态变化规律,模型精度不高直接影响温室环境控制性能。针对模型的这种复杂特性,该文以温度模型为例,提出利用连续-离散递推预测误差算法,对非线性模型参数和状态进行在线估计,以提高模型精度。首先,考虑加热和通风2种控制输入,建立了温室温度模型。然后,论述了该算法的原理和优势,算法通过引入并调整增益矩阵,对系统噪声进行在线更新,减少了系统噪声初始化偏差对参数估计收敛性的影响。最后,基于试验温室实测数据,对温室温度模型进行了在线辨识仿真,结果表明,利用连续-离散递推预测误差算法辨识模型拟合度为93.7%,扩展卡尔曼滤波器拟合度为89.5%,该文提出的算法在预测温室温度方面更为有效。 相似文献
3.
T. V. Denisova K. Sh. Kazeev S. I. Kolesnikov V. F. Val’kov 《Eurasian Soil Science》2007,40(9):978-985
The dynamics of changes in the number of microorganisms and biochemical properties of an ordinary chernozem were studied in model experiments 3, 30, and 90 days after the soil was subjected to gamma radiation at doses of 0.12–2.0 Mrad. The microscopic fungi are the most radiosensitive soil microorganisms. In 90 days of incubation after the gamma radiation, the number of microorganisms remained lower than that in the control variant by 31–96% in accordance with the dose. The enzyme activity of the ordinary chernozem, as compared to that of the microorganisms, was more resistant to the gamma radiation. The integral index of the soil biological state (ISBSI) decreased by 20–63% upon the radiation depending on the dose applied. After 90 days, the ISBSI value was close to the control variant (doses of 0.1–0.5 Mrad), whereas, in the variants with high doses of radiation (1.0 and 2.0 Mrad), its values were 46 and 59% lower, respectively, than in the control. The rate of restoring of the biological properties was related to the dose of radiation: the less the dose, the quicker the rate of restoration of the biological properties of the ordinary chernozem. However, at the high levels of gamma radiation, some biological properties were not restored even after 90 days. 相似文献
4.
土壤水空间分布结构的时间稳定性 总被引：19，自引：2，他引：19
通过在野外 3 5m× 3 5m的正方形试验区域高密度布置多个电极和定时扫描测定土壤电阻的方法 ,利用反演计算和土壤电阻率与含水量之间的关系 ,计算出了不同时间的土壤含水量在三维空间上的分布。通过对由此获得的含水量资料的分析 ,探讨了土壤水在三维空间上的分布特征及其在时间上的稳定性。结果表明 ,试验区的土壤含水量在三维空间上的分布是非均质的和各向异性的 ,这种非均质性不是随机的而是具有一定的结构或模式 ,这一结构或模式在时间上是相对稳定的。 相似文献
5.
Canopy temperatures, when measured remotely, offer a method of estimating evapotranspiration with surface energy balance models. Equations which have been developed by others have been evaluated only at a limited number of locations and with a few crops. Our study was conducted at several locations with weighing lysimeters with a variety of crops around the United States: Brawley, CA; Temple, TX; Lincoln, NE; St. Paul, MN; Fargo, ND; Kimberly, ID; and Davis, CA, to evaluate evapotranspiration utilizing canopy temperature as an input into the surface energy balance. The results show that evapotranspiration calculated from the aerodynamic resistance form of the surface energy balance was well correlated with lysimeter measurements at all locations. The errors using the surface energy balance were less than 10% in all cases for full ground cover. The Bartholic—Namken—Wiegand method was more closely coupled to net radiation than canopy temperature.Under partial canopy cover, differences between the two models were apparent. The Bartholic—Namken—Wiegand model overpredicted when the actual evapotranspiration was above 200 W m?2 because of its insensitivity to surface temperature. However, the surface energy balance model exhibited only a slight overprediction above 200 W m?2 when a weighed composite surface temperature (representative of bare soil and crop temperature) was used. This small overprediction could be overcome by considering the soil heat flux term. There was no location bias in the surface energy balance model, which shows that it should work well at other locations. 相似文献
6.
黄土丘陵区退耕坡面草地恢复与土壤物理性质空间分异特征 总被引：2，自引：2，他引：0
为了解地形对草地恢复与土壤物理性质的影响以及草地恢复与土壤物理性质之间的影响机制,因地制宜为当地生态恢复提供科学依据。选择吴起县枣庄沟小流域为研究区,对退耕坡面不同坡位草地恢复与土壤物理性质分异特征进行研究。从峁顶到沟底设置8个采样位置,在4面坡共布设128个采样点进行植被调查和土样采集,将0—40 cm土壤分0—10,10—20,20—40 cm 3层进行土壤物理性质测定,并分析其与植被分布的相关关系。结果表明:不同坡位植被分布与土壤物理性质均表现出沟缘线以上的下坡位较优,沟缘线以下的陡沟坡较差的趋势;植被恢复对土壤团聚体有明显改善作用,但对其与土壤物理性质的改善主要集中在0—20 cm表层土壤,对20—40 cm土壤影响较弱;坡度对植被盖度与土壤容重、孔隙度和饱和持水量影响显著且具有极显著相关性,但对团聚体与颗粒组成无显著影响;植被恢复对土壤颗粒组成改善效果缓慢,若土壤颗粒组成被破坏,短期内很难恢复。 相似文献
7.
留兰香作为一种优良的水土保持经济植物,是我国南方红壤侵蚀荒坡地治理与开发的优良作物品种之一,有如下几方面的优势：①耐旱、耐瘠,适应性强;②辅以科学的栽培管理措施,生长快,覆盖密,覆盖时间长,蓄水效率达５０－３ ％ ,减沙效率达７１－５ ％ ,能有效地控制水土流失;③留兰香油可作调味香料,也可开发成系列清凉保健产品和高效低毒的植物杀虫、驱虫制剂,经济效益佳。总结了红壤侵蚀荒坡地种植留兰香的主要技术措施,并对其生态、经济效益进行了分析评价。 相似文献
8.
红外光谱在土壤学中的应用 总被引：5，自引：0，他引：5
红外光谱技术在土壤学中已得到较广泛的应用,它能够综合地反映土壤体系的物质组成及其相互作用,为研究土壤中物质循环及其作用过程提供了新的手段。本文回顾了近年来红外光谱技术在土壤学中的应用,包括透射光谱在土壤定性分析中的应用,并重点介绍红外反射光谱与化学计量学相结合的光谱建模技术发展情况及其在土壤定量分析中的应用。同时本文探讨了基于光声效应的红外光声光谱技术,红外光声光谱非常适合用于土壤这种复杂、非透明体系的研究,能够克服传统透射和反射光谱中存在的缺陷,测定快速方便,并具有较高的灵敏度和测量精确度,具有很大的应用潜力。 相似文献
9.
R. S. Truskavetskii 《Eurasian Soil Science》2014,47(7):687-693
Methodological aspects of studying the organic carbon budget of drained peat bogs used in agriculture are discussed. Difficulties in the assessment of carbon budget on the basis of measured carbon inflows and outflows are shown. The “soil pool” model of the carbon budget is suggested. It is based on the results of long-term experimental studies of a drained peatland in Ukrainian Polesie. An algorithm for calculating the carbon budget in the aerated part of the peatland—the peat soil proper—is developed with due account for a gradual involvement of the deep peat layers into the zone of soil processes. Data on the loss of dry peat mass and organic carbon per in the course of peat mineralization and surface subsidence are given with due account for the nature of the peatland and the duration of its agricultural use. 相似文献
10.
岩溶区根系地下生境对土壤微生物生物量的影响 总被引：2，自引：0，他引：2
选择岩溶区3种不同的典型根系地下生境类型土壤作为研究对象(类型Ⅰ——白云岩水平产状多层空间类型、类型Ⅱ——白云岩倾斜产状多层空间类型及类型Ⅲ——白云岩直立产状多层空间类型),分析不同类型及层次对土壤微生物生物量的影响,以及土壤养分、土壤酶活性的变化。结果表明:(1)根系地下生境类型和层次对土壤微生物生物量的影响极显著(p<0.01);(2)3种类型的土壤微生物生物量差异极显著(p<0.01),均随土壤层次的下降而降低,类型Ⅰ的微生物环境较差,类型Ⅱ较好,类型Ⅲ居中;(3)类型Ⅰ在一定程度上能促进碳循环,类型Ⅱ利于有机碳的循环、氮的供应,类型Ⅲ利于磷的供应及有机物质的氧化。该研究可为探索岩溶地区的根系地下生境及其土壤条件,并为同等条件的土壤肥力评价、植被恢复技术研究提供参考。 相似文献
11.
水分是限制干旱、半干旱地区植被生态系统恢复的重要因素之一,合理量化长时间尺度下生态系统中的土壤蒸发量及其变化趋势,对于提高生态系统水资源利用效率具有重要意义。基于黑河下游额济纳绿洲七道桥胡杨林保护区实测数据,分析了胡杨林生态系统土壤蒸发和蒸散发的变化趋势及其与环境因子的相关性,通过Shuttleworth-Wallace模型和改进的双源模型中土壤蒸发的计算公式对其进行模拟,对比分析了二者的模拟精度及参数敏感性,结果表明：(1)土壤蒸发和蒸散发各月的日变化及整个试验期内的变化均呈先升高后降低的单峰变化趋势;(2)胡杨林生态系统土壤蒸发在蒸散发中所占比例的变化范围为30.2%～72.2%;(3)净辐射对土壤蒸发的影响最显著;(4)改进的双源模型中,土壤蒸发的计算公式可以不考虑复杂阻力参数的计算过程,且与传统的双源SW模型相比具有更高的模拟精度。研究提出了适用于干旱区森林植被生态系统中土壤蒸发模拟的双源优化模型,为土壤蒸发模拟提供了新的思路与方法。 相似文献
12.
土壤酶在关键元素生物地球化学循环、动植物健康维持、环境污染净化等方面起着不可替代的重要作用,同时还是土壤污染程度评价的辅助指标之一。然而,由于土壤物理、化学和生物学性质的差异,以及研究方法的多样化,导致重金属与土壤酶活性之间的关系十分复杂,阻碍了土壤酶在土壤质量和健康评价中的应用。系统阐述了重金属污染对土壤酶的生态毒理效应,及其对土壤酶催化动力学特征的影响,构建了土壤-重金属-微生物对土壤酶作用的概念模型,并探讨未来的研究趋势和方向。土壤酶活性测定高效、便宜,且对重金属污染敏感,是极具潜力的土壤重金属污染评价的生物学指标,但仅采用土壤酶活性可能高估或低估重金属的生态毒性,加之当前对土壤酶的选择、活性的测定均缺乏统一的标准,致使难以建立重金属毒性阈值与土壤理化性质或土壤重金属有效性之间的定量关系,最终导致土壤酶在土壤污染生态风险评价中存在争议。未来亟需通过新技术和数学模型,深入揭示不同类型土壤中酶对重金属胁迫的响应机理,构建土壤性质与毒性阈值关系的经验模型,可为加强土壤酶在土壤质量和健康评价中的应用提供重要的理论依据。 相似文献
13.
该研究对基于注意力机制的长短期记忆（Attention-Based Long Short Term Memory，AT-LSTM）模型对蒸散量（Evapotranspiration，ET）模拟的可行性和有效性进行验证，以提高环境数据缺失情况下的蒸散量模拟精度。基于盐池县2012-2017年的每30 min环境数据，利用不同环境因子组合构建基于注意力机制的LSTM模型，并将其与极限学习机（Extreme Learning Machine，ELM）模型、支持向量机（Support Vector Machine，SVM）模型、长短期记忆（Long Short Term Memory，LSTM）模型在日尺度、月尺度和季节尺度上进行对比分析。结果表明：与其他3种模型相比，当输入环境因子变化时，AT-LSTM模型模拟精度变化很小，模拟效果均较好。当输入空气温度、净辐射、相对湿度、土壤温度、土壤含水率所有环境因子时，基于AT-LSTM模型的模拟效果最好，均方根误差（Root Mean Square Error，RMSE）为0.013 mm/30 min，平均绝对误差（Mean Absolute Error，MAE）为0.006 mm/30 min，相关系数（Correlation Coefficient，R）值为0.905。且无论是从小时尺度、日尺度和月尺度来看，AT-LSTM模型的模拟效果均优于其他3种模型。在环境因子缺失的情况下，净辐射对盐池县ET的模拟贡献程度最大，仅输入净辐射时，AT-LSTM模型模拟得到的RMSE和MAE分别为0.014、0.007 mm/30 min，R为0.892，模型模拟精度较高，AT-LSTM模型模拟精度高，模型稳定性强，对蒸散量模拟预测具有一定的适用性，仅输入净辐射的AT-LSTM模型可以作为环境数据缺失条件下的蒸散量预测模型。 相似文献
14.
黄河三角洲盐渍化荒地种植植物对土壤改良、磷形态转化及有效性的影响 总被引：1，自引：0，他引：1
为了明确种植不同植物对黄河三角洲盐渍化荒地改良效果、土壤磷形态转化及增效调控机制,研究了在生长芦苇的盐渍化荒地改变种植植物(柽柳、白蜡、苜蓿)的改良措施对土壤磷形态转化及有效含量的影响。结果表明:与荒地芦苇相比,3种植物种植均能显著提高0—20 cm土壤磷酸酶活性,柽柳种植显著降低0—20 cm土壤pH,促进0—20 cm土壤大颗粒团聚体形成,提高0—40 cm土壤有机碳含量,显著增加0—100 cm土壤盐渍化程度,促使土壤速效磷(Ca2—P)和缓效磷(Ca8—P和Al—P)向难溶性磷(Ca10—P)的转化,导致土壤磷有效性降低;白蜡种植显著降低0—100 cm土壤盐渍化程度及60—100 cm土壤pH,0—20 cm土壤小颗粒团聚体比例增加,0—40 cm土壤有机碳含量显著降低,促进土壤难溶性磷(O—P)向缓效磷(Fe—P)转化,有利于土壤磷有效性提高;苜蓿种植显著增加0—20 cm土壤有效磷含量,提高0—20 cm土壤磷酸酶活性,促进难溶性磷(O—P)、缓效磷(Ca8—P和Al—P)向速效磷的转化,0—20 cm土壤大颗粒团聚体比例增加有利于提升土壤磷有效性,其60—100 cm土壤pH增加不利于土壤磷的有效性提高;3种植物种植后土壤微生物量碳和微生物量磷显著降低,微生物量氮显著增加,土壤呼吸强度及脲酶活性均无显著变化。综上所述,白蜡种植最有利于降低土壤盐渍化程度和pH,苜蓿种植最有利于0—20 cm土壤磷有效性的提高,3种植物种植对20—100 cm土壤磷有效性无显著促进作用。由于3种植物对盐渍荒地改良时间较短,土壤微生物种群动态变化及对土壤磷形态转化过程及调控机制尚需深入研究。 相似文献
15.
[目的]研究不同种植年限压砂地及裸地不同土层土壤盐分的空间变异特征,为西北干旱地区土壤盐渍化改良和利用提供理论依据。[方法]以甘肃省景泰县压砂地及裸地不同土层土壤盐分数据为基础,运用经典统计学和地统计学相结合的方法,分析土壤盐分统计特征值,半方差模拟模型及其拟合参数和等值线分布图。[结果]压砂地土壤盐分均值明显低于裸地,且裸地老砂地新砂地中砂地,裸地与压砂地各层土壤盐分的均值差异较大,且土层Ⅳ(30—50cm)土层Ⅲ(20—30cm)土层Ⅱ(10—20cm)土层Ⅰ(0—10cm);裸地Ⅱ,Ⅲ,Ⅳ层,中砂地各层土壤盐分属于弱变异性,其他各地型各土层土壤盐分都属于中等变异性。裸地Ⅰ,Ⅲ层,新砂地第Ⅲ层,中砂地第Ⅰ层,老砂地Ⅰ,Ⅱ,Ⅲ层土壤盐分半方差函数最佳理论模型为指数模型,裸地第Ⅱ层为线性模型,其他各地型各土层均为球状模型。裸地第Ⅱ层土壤盐分具有弱空间相关性,其余各土层土壤盐分均具有强相关性。试验区土壤盐分北部高于南部,且各土层土壤盐分在一定范围内存在空间上的变异性和相关性。[结论]土壤表层压砂能有效减小土壤盐分表聚,抑制土壤次生盐渍化,不同种植年限压砂地不同土层土壤盐分在一定范围内存在空间上的变异性和相关性。 相似文献
16.
大尺度地表土壤水分信息的获取对水资源管理、农业生产以及气候变化等相关研究具有重要意义。TAU-OMEGA（$ \tau -\omega $）模型是利用被动微波遥感技术进行大尺度土壤水分信息提取的常用模型。由于$ \tau -\omega $模型忽略了植被层的体散射作用,该模型仅适用于L波段,存在C波段适用性差及模型参数无法定量计算的问题。该研究在分析植被冠层对微波散射机制的基础上,通过增加反映冠层多次散射作用的辐射添加项对$ \tau -\omega $模型进行了改进,成功解决了模型在C波段的适用性问题;通过理论推导,得出了模型$ \omega $参数的理论计算方法,基于模拟数据集,实现了基于冠层叶面积指数的模型$ \omega $和$ \tau $参数的计算,解决了$ \tau -\omega $模型中$ \omega $参数无法根据遥感数据进行定量计算的问题。以玉米冠层为例,在C波段（6.6 GHz）,改进的$ \tau -\omega $模型对地表微波辐射亮温的模拟值与实测数据保持了较好的一致性,模拟误差较改进前有了极大的下降,V极化均方根误差为3.02 K,H极化均方根误差为3.94 K,结果表明了该研究提出的模型改进与参数化方案的合理性,研究结果为联合光学和被动微波遥感数据进行大尺度土壤水分反演奠定了基础。 相似文献
17.
求解干旱地区土壤溶液Ca2+浓度和pH的逐步逼近算法 总被引：1，自引：0，他引：1
在土壤碳酸钙淋溶淀积过程的建模中,需要根据土壤碳酸钙化学热力学平衡原理求解土壤溶液中的Ca2 浓度和pH值,其中有些参数难以获得（如有关离子的活度系数）,不能直接求解,导致无法实现其过程的计算机模拟。本文针对这一难题,提出了一种逐步逼近算法,在已知土壤空气中的二氧化碳分压和土壤温度的情况下,可求得干旱地区土壤溶液中的Ca2 浓度和pH值,为土壤碳酸钙淋溶淀积过程的计算机模拟提供了重要的技术支持。本算法理论依据充分、结果稳定精度高、程序简便易实现,并在CAEDP模型中已得到了应用和验证。 相似文献
18.
Haddad M Herent MF Tilquin B Quetin-Leclercq J 《Journal of agricultural and food chemistry》2007,55(15):6082-6086
The microbiological contamination of raw plant materials is common and may be adequately reduced by radiation processing. This study evaluated the effects of gamma- and e-beam ionizing radiations (25 kGy) on three plants used as food or as medicinal products (Thymus vulgaris L., Eucalyptus radiata D.C., and Lavandula angustifolia Mill.) as well as their effects on extracted or commercial essential oils and pure standard samples. Comparison between irradiated and nonirradiated samples was performed by GC/FID and GC/MS. At the studied doses, gamma and e-beam ionizing radiation did not induce any detectable qualitative or quantitative significant changes in the contents and yields of essential oils immediately after ionizing radiation of plants or commercial essential oils and standards. As the maximum dose tested (25 kGy) is a sterilizing dose (much higher than doses used for decontamination of vegetable drugs), it is likely that even decontamination with lower doses will not modify yields or composition of essential oils of these three plants. 相似文献
19.
Ahmed Abed Gatea AL-SHAMMARY Abbas Z. KOUZANI Akif KAYNAK Sui Yang KHOO Michael NORTON Will GATES 《土壤圈》2018,28(4):581-596
Measurement of soil bulk density is important for understanding the physical, chemical, and biological properties of soil. Accurate and rapid soil bulk density measurement techniques play a significant role in agricultural experimental research. This review is a comprehensive summary of existing measurement methods and evaluates their advantages, disadvantages, potential sources of error, and directions for future development. These techniques can be broadly categorised as direct and indirect methods. Direct methods include core, clod, and excavation sampling, whereas indirect methods include the radiation and regression approaches. The core method is most widely used, but it is time consuming and difficult to use for sampling multiple soil depths. The size of the coring cylinder used, operator experience, sampling depth, and in-situ soil moisture content significantly affect its accuracy. The clod method is suitable for use with heavy clay soils, and its accuracy is dependent on equipment calibration, drying time, and operator experience, but the process is complicated and time consuming. Excavation techniques are most commonly used to evaluate the bulk density of forest soils, but have major limitations as they cannot be used in soils with large pores and their measurement accuracy is strongly influenced by soil texture and the type of analysis selected. The indirect methods appear to have greater accuracy than direct approaches, but have higher costs, are more complex, and require greater operator experience. One such approach uses gamma radiation, and its accuracy is strongly influenced by soil depth. Regression methods are economical as they can make indirect measurements, but these depend on good, quality data of soil texture and organic matter content and geographical and climatic properties. Also, like most of the other approaches, its accuracy decreases with sampling depth. 相似文献
20.
A soil—plant—atmosphere model for sunflower (Helianthus annuus L.), together with clear sky weather data for several days, is used to study the relationship between canopy temperature and root-zone soil water potential. Considering the empirical dependence of stomatal resistance on insolation, air temperature and leaf water potential, a continuity equation for water flux in the soil—plant—atmosphere system is solved for the leaf water potential. The transpirational flux is calculated using Monteith's combination equation, while the canopy temperature is calculated from the energy balance equation. The simulation shows that, at high soil water potentials, canopy temperature is determined primarily by air and dew point temperatures. These results agree with an empirically derived linear regression equation relating canopy-air temperature differential to air vapor pressure deficit. The model predictions of leaf water potential are also in agreement with observations, indicating that measurements of canopy temperature together with a knowledge of air and dew point temperatures can provide a reliable estimate of the root-zone soil water potential. 相似文献