农桐间作的养分循环

对农桐间作（以桐为主间作型）的养分循环规律进行了研究。结果表明，泡桐各器官营养元素的含量随季节而变化。对营养元素的年吸收量为４７１．９５９５ｋｇ／ｈｍ￣２，其中氮１５５．１４２９ｋｇ／ｈｍ￣２，磷８０．０８２１ｋｇ／ｈｍ￣２，钾８７．０３９４ｋｇ／ｈｍ￣２，钙１１９．４６０３ｋｇ／ｈｍ￣２，镁３０．２３４８ｋｇ／ｈｍ￣２。营养元素的年归还量为３３１．６１５５ｋｇ／ｈｍ￣２，其中氮１０２．５７２１ｋｇ／ｈｍ￣２，磷４３．２９２２ｋｇ／ｈｍ￣２．钾６３．６４９７ｋｇ／ｈｍ￣２，钙９７．３５８６ｋｇ／ｈｍ￣２，镁２４．７４２９ｋｇ／ｈｍ￣２。营养元素的循环率为７０、２６％，其中氮６６．１１％，磷５４．０６％，钾７３．１３％，钙８１．５０％，镁８１．８４％。     

番茄反夏栽培的营养特点及施肥技术研究

本试验在阳山县江英乡和清新县石湖镇４６０ｍ以上的石灰岩山区进行．试验得出．（１）番茄反夏栽培的营养特点：高产番茄养分吸收量远比低产番茄高，高产番茄吸氮２１６．４５ｋｇ／ｈｍ２，吸磷４０．２０ｋｇ／ｈｍ２，吸钾３９０．１５ｋｇ／ｋｍ２，吸收氮、磷、钾比例为１：０．１９：１．８０；（２）各生育期氮、磷、钾吸收规律：苗期吸收少，随生长期的推进而提高，尤其是番茄开花之后其提高的速度更快；（３）施肥技术：一造施肥总量，氮３６０．７５—４４４．４５ｋｇ／ｈｍ２，磷２２５．７５—２６７．９０ｋｇ／ｈｍ２，钾３４０．３５—４８７６５ｋｇ／ｈｍ２．各生育期合理配施的原则是前轻、中重、后补足．     

闽东南旱地土壤养分状况与花生平衡施肥研究

２８个土壤样品的养分测定和吸附试验以及８个田间肥效试验表明，闽东南旱地土壤的Ｎ、Ｐ、Ｋ、Ｂ是花生的普遍养分限制因子．部分土壤还缺乏Ｚｎ和Ｍｇ等养分．赤砂土的肥料三要素最佳用量分别为Ｎ５４ｋｇ／ｈｍ２、Ｐ２Ｏ５５５ｋｇ／ｈｍ２、Ｋ２Ｏ８７ｋｇ／ｈｍ２；红壤性水稻土为Ｎ５２ｋｇ／ｈｍ２、Ｐ２Ｏ５６３ｋｇ／ｈｍ２、Ｋ２Ｏ９２ｋｇ／ｈｍ２；海砂土为Ｎ９４ｋｇ／ｈｍ２、Ｐ２Ｏ５４２ｋｇ／ｈｍ２、Ｋ２Ｏ８５ｋｇ／ｈｍ２．１０个对比试验表明，花生平衡施肥比群众常规施肥平均增产４７１ｋｇ／ｈｍ２，增产率为１４．９％，每ｈｍ２净增收２０５３元．     

异丙隆在土壤和小麦中的降解与残留

在扬州和聊城两地进行了除草剂异丙隆在小麦上和麦田土壤中的残留动态和最终残留量试验，结果表明，异丙隆在小麦植株和土壤中消解较快，消解半衰期分别为３～４ｄ和８～１４ｄ；收获时小麦籽粒中异丙隆残留量小于０．０４ｍｇ／ｋｇ。推荐暂定异丙隆在小麦上ＭＲＩＬ值为０．５ｍｇ／ｋｇ。２５％异丙隆可湿性粉剂，按７．５ｋｇ／ｈｍ￣２用量，在次年早春（２月）使用，籽粒中异丙隆最终残留量不会超过ＭＲＬ值，对小麦是安全的。     

珠江口红树林硫的累积和循环研究

主要研究了珠江口红树林硫的累积和循环特点，并探讨其对土壤中硫累积的影响．结果表明，珠江口五个红树群落硫的贮存量平均为１７０．４２ｋｇ／ｈｍ２；在群落硫元素的生物循环中，年存留量平均为１７．６０１ｋｇ／ｈｍ２，年归还量平均为３５．６０３ｋｇ／ｈｍ２，年吸收量平均为５３．２０４ｋｇ／ｈｍ２，周转期为３－８ａ，富集率均大于１．选定浅海沉积物的平均含硫量作为林下土壤成土母质的本底含硫量，估算红树植物生长后土壤含硫量的变化，并与群落硫的年归还量作比较．红树林对其林下土壤硫的累积作用有两方面，一是对海水硫的生物选择吸收与归还，二是为海水中的ＳＯ４（２－）为黄铁矿提供有机还原剂和嫌气微生物的能源，尤以后者的作用更重要．     

绿磺隆对水稻的残留危害剂量

用田间模拟试验法，研究了土壤中绿磺隆不同添加量与水稻危害剂量的关系。结果表明：稻田绿磺隆添加量超过０．３７５ｇ（ＡＩ）／ｈｍ￣２时，就可能对水用产生危害，在此用量水平下，绿磺隆在耕层土壤中的平均残留浓度为０．１７μｇ／ｋｇ，按此推算，麦田按正常用量的２倍量（３０ｇ／ｈｍ￣２）施用，在种麦期间绿磺隆在麦田土壤中的半衰期超过３２．１ｄ．即会对水稻产生危害。     

草莓有机与无机种植系统能流和经济流的比较研究

通过３年田间试验，比较分析了草莓有机与无机种植系统的能流、经济流及对土壤环境的影响。结果表明，有机系统草莓产量、经济效益均高于无机系统；有机系统能量产投比仅为无机系统的２５％，但投入的绝大部分为可再生能源；有机系统土壤有机质、微生物量高于无机系统，具有更好的土壤条件     

配施的有机无机肥料氮在红壤性水稻土中的残留特征

（１５）Ｎ追踪结果显示，熟化上（Ａ）和低肥力土（Ｃ）有机、无机肥料配施的氮的残留特征均为随配施有机成分和土壤肥力水平的变化而变化．肥力制约残留水平，肥料氮总平衡影响残留率一利用率一损失率的关系；配施有机肥是造成氮残留差异的基本因素，相关分析表明，总残留主体为有机肥氮，残留率随有机肥Ｃ／Ｎ和木质素含量的增减而增减；影响无机肥氮残留的相关因素较复杂．有机氮残留量占总残留量的百分数与无视氮残留量占总残留量的百分数之比，在Ａ，Ｃ两种土壤中约为２．肥力对氮残留作用的实质是，肥料氮在低肥力土中具固持优势，而在熟化土中具矿化利用优势．肥力因素对无机氮残留的影响更显著．根据配施组合中有机成分Ｃ／Ｎ－木质素含量与氮残留／平衡特征的关系．将不同配施组合划分为三大类型。     

土壤中绿磺隆残留量生物测定方法

用生物测定方法测定了土壤中绿磺隆残留量，建立了绿磺隆浓度（Ｙ）与玉米根长（Ｘ）之间的相关模式：Ｙ＝３０．５６２－３６．３８ＩｎＸ＋１４．８２８（ＩｎＸ）￣２＋２．０４３（ＩｎＸ）￣３．此模式适用于土壤中０．１～４．０μｇ／ｋｇ浓度范围的绿磺隆残留量测定，最低检出量为０．１μｇ／ｋｇ。     

烤烟优质高产施肥技术研究初报

１９９７～１９９８年在广东省五华县的紫色土田进行了烤烟优质高产施肥试验。结果表明，在一定的氮磷施用量条件下，烤烟的产量、质量及产值都是随着施钾比例的提高而提高。在一定的配比下，烤烟的产量及产值在施氮 １６５ ｋｇ／ｈｍ~２以下均随施氮量的增加而提高；均价和优级烟率以中等氮水平（ １３５ ｋｇ／ｈｍ~２）的为最高。本文还提出烤烟的最佳施肥方案。     

LES validation of urban flow,part II: eddy statistics and flow structures

Time-dependent three-dimensional numerical simulations such as large-eddy simulation (LES) play an important role in fundamental research and practical applications in meteorology and wind engineering. Whether these simulations provide a sufficiently accurate picture of the time-dependent structure of the flow, however, is often not determined in enough detail. We propose an application-specific validation procedure for LES that focuses on the time dependent nature of mechanically induced shear-layer turbulence to derive information about strengths and limitations of the model. The validation procedure is tested for LES of turbulent flow in a complex city, for which reference data from wind-tunnel experiments are available. An initial comparison of mean flow statistics and frequency distributions was presented in part I. Part II focuses on comparing eddy statistics and flow structures. Analyses of integral time scales and auto-spectral energy densities show that the tested LES reproduces the temporal characteristics of energy-dominant and flux-carrying eddies accurately. Quadrant analysis of the vertical turbulent momentum flux reveals strong similarities between instantaneous ejection-sweep patterns in the LES and the laboratory flow, also showing comparable occurrence statistics of rare but strong flux events. A further comparison of wavelet-coefficient frequency distributions and associated high-order statistics reveals a strong agreement of location-dependent intermittency patterns induced by resolved eddies in the energy-production range. The validation concept enables wide-ranging conclusions to be drawn about the skill of turbulence-resolving simulations than the traditional approach of comparing only mean flow and turbulence statistics. Based on the accuracy levels determined, it can be stated that the tested LES is sufficiently accurate for its purpose of generating realistic urban wind fields that can be used to drive simpler dispersion models.     

LES validation of urban flow,part I: flow statistics and frequency distributions

Essential prerequisites for a thorough model evaluation are the availability of problem-specific, quality-controlled reference data and the use of model-specific comparison methods. The work presented here is motivated by the striking lack of proportion between the increasing use of large-eddy simulation (LES) as a standard technique in micro-meteorology and wind engineering and the level of scrutiny that is commonly applied to assess the quality of results obtained. We propose and apply an in-depth, multi-level validation concept that is specifically targeted at the time-dependency of mechanically induced shear-layer turbulence. Near-surface isothermal turbulent flow in a densely built-up city serves as the test scenario for the approach. High-resolution LES data are evaluated based on a comprehensive database of boundary-layer wind-tunnel measurements. From an exploratory data analysis of mean flow and turbulence statistics, a high level of agreement between simulation and experiment is apparent. Inspecting frequency distributions of the underlying instantaneous data proves to be necessary for a more rigorous assessment of the overall prediction quality. From velocity histograms local accuracy limitations due to a comparatively coarse building representation as well as particular strengths of the model to capture complex urban flow features with sufficient accuracy are readily determined. However, the analysis shows that further crucial information about the physical validity of the LES needs to be obtained through the comparison of eddy statistics, which is focused on in part II. Compared with methods that rely on single figures of merit, the multi-level validation strategy presented here supports conclusions about the simulation quality and the model’s fitness for its intended range of application through a deeper understanding of the unsteady structure of the flow.     

Experimental surface flow visualization and numerical investigation of flow structure around an oblong stockpile

Emission factors are largely used to quantify particle emissions from industrial open storage piles. These factors are based on the knowledge of velocity distribution and flow patterns over the stockpile surface which still requires further research. The aim of the present work is to investigate the airflow characteristics over a single typical oblong pile and in its near-ground surroundings for various wind flow directions. Wind tunnel experiments using an oil-film surface coating technique were carried out for near-wall flow visualization. Numerical simulation results, favorably compared to PIV measurements, were used to allow comparison analysis of flow features. For the stockpile oriented 90° to the wind main direction, typical topology of flow around wall-mounted obstacles were observed, notably a wake zone downstream the pile including two main counter-rotating vortices. Further analysis of numerical wall shear stress distribution and streamlines indicates that two complex three-dimensional vortical flow structures develop downstream the pile. For other incoming wind flow directions (30 and 60°), the flow characteristics over the storage pile greatly differ as a single helical main vortex develops from the pile’s crest. Corresponding high values of wall shear stress are noticed downstream the storage pile. For each configuration studied, downwash and upwash zones are induced by the vortical structures developed. This near-wall flow topology combined with areas of high friction levels may be linked to potential dust emission from the ground surface surrounding industrial stockpiles.     

Surface waves and roughness in self-aerated supercritical flow

In high-velocity open channel flows, free-surface aeration is commonly observed. The effects of surface waves on the air–water flow properties are tested herein. The study simulates the air–water flow past a fixed-location phase-detection probe by introducing random fluctuations of the flow depth. The present model yields results that are close to experimental observations in terms of void fraction, bubble count rate and bubble/droplet chord size distributions. The results show that the surface waves have relatively little impact on the void fraction profiles, but that the bubble count rate profiles and the distributions of bubble and chord sizes are affected by the presence of surface waves.     

Exchange flow between open water and floating vegetation

This study describes the exchange flow between a region with open water and a region with a partial-depth porous obstruction, which represents the thermally-driven exchange that occurs between open water and floating vegetation. The partial-depth porous obstruction represents the root layer, which does not penetrate to the bed. Initially, a vertical wall separates the two regions, with fluid of higher density in the obstructed region and fluid of lower density in the open region. This density difference represents the influence of differential solar heating due to shading by the vegetation. For a range of root density and root depths, the velocity distribution is measured in the lab using PIV. When the vertical wall is removed, the less dense water flows into the obstructed region at the surface. This surface flow bifurcates into two layers, one flowing directly through the root layer and one flowing beneath the root layer. A flow directed out of the vegetated region occurs at the bed. A model is developed that predicts the flow rates within each layer based on energy considerations. The experiments and model together suggest that at time- and length-scales relevant to the field, the flow structure for any root layer porosity approaches that of a fully blocked layer, for which the exchange flow occurs only beneath the root layer.     

Characterizing and sexing laminarialean meiospores by flow cytometry

Selected features of Alaria marginata Postels et Ruprecht, Laminaria saccharina (L.) Lamouroux and Cymathere triplicata (Postels et Ruprecht) J. G. Agardh meiospores were described using flow cytometry. The relative sizes (forward scatter), chlorophyll contents (red fluorescence) and DNA contents (blue fluorescence) were measured on living, fixed, Hoechst and DAPI (4,6-diamidino-2-phenylindole) stained and unstained cells. The meiospores were similar among species and the frequency distributions of the monitored features were essentially normal. Meiospores sorted for low blue fluorescence departed significantly from the expected 1:1 male to female ratio in favour of the male. Cells sorted for high blue fluorescence did not result in a departure from the expected 1:1 ratio. We suggest that our ability to sexually sort meiospores is a result of a differential nonstoichiometric fluorescence in DNA, which possibly reflects a greater DNA compactedness and/or nuclear protein content in the male meiospores.     

Monitoring and estimating the flow conditions and fish presence probability under various flow conditions at reach scale using genetic algorithms and kriging methods

The combination of current velocity and water depth influences stream flow conditions, and fish activities prefer particular flow conditions. This study develops a novel optimal flow classification method for identifying types of stream flow based on the current velocity and the water depth using a genetic algorithm. It is applied to the Datuan stream in northern Taiwan. Fish were sampled and their habitat investigated at the study site during the spring, summer, fall and winter of 2008-2009. The current velocity, water depth and maps of the presence probability of fish were estimated by ordinary and indicator kriging. The optimal classification results were compared with the classification results obtained using the Froude number and empirical methods. The flow classification results demonstrate that the proposed optimal flow classification method that considers depth-velocity and optimally identified criteria for classifying flow types, yields a current velocity and water depth of 0.32 (m/s) and 0.29 (m), respectively, and classifies the flow conditions in the study area as pool, run, riffle and slack. The variography results of the current velocity and the water depth data reveal that seasonal flows are not spatially stationary among seasons in the study area. Kriging methods and a two-dimensional hydrodynamic model (River 2D) with empirical and optimal flow classification methods are more effective than the Froude number method in classifying flow conditions in the study area. The flow condition classifications and probability maps were generated by River 2D, ordinary kriging and indicator kriging, to quantify the flow conditions preferred by Sicyopterus japonicus in the study area. However, the proposed optimal classification method with kriging and River 2D is an effective alternative method for mapping flow conditions and determining the relationship between flow and the presence probability of target fish in support of stream restoration.     

A fully coupled two-dimensional flow—vegetation routing model in open channel flow

Environmental Fluid Mechanics - Aquatic vegetation modifies the in-stream roughness and hence influences the magnitude and distribution of flow parameters in the main channel and the flood plain....