Sedimentology models from activity concentration measurements: application to the “Bay of Cadiz” Natural Park (SW Spain)

A previous study on seabed sediments of the Bay of Cadiz (SW of Spain) enabled us to identify several relations between sedimentological variables and activity concentrations of environmental radionuclides such as ¹³⁷Cs, ²²⁶Ra, ²³²Th and ⁴⁰K. In this paper the study has been extended to a large neighbouring inter-tidal area in order to establish if the above mentioned models can be generalized. As a result we have determined that the measured activity concentrations are closely to the values predicted by the theoretical models (correlation coefficient range = 0.85–0.93).     

海绵型雨水口初期雨水截污能力优化研究

选用装配式选配截污型雨水口,以土工布、不锈钢筛网和5种不同填料作为过滤模块,配置人工模拟雨水用于试验,研究其在不同截污装置下对初期雨水中悬浮物（SS）、化学需氧量（COD）、氨氮（NH₄ ⁺-N）、总氮（TN）和总磷（TP）等污染物的去除效果,测试其对初期雨水径流污染的削减能力,并综合评价其在实际工程运用中的可行性与经济性。结果表明：在土工布、不锈钢筛网过滤模块中,土工布对SS有较好的去除效果,不锈钢筛网则需将孔径降至0.074 mm时才对SS有较明显的去除效果,但二者对COD、NH₄ ⁺-N、TN和TP的去除效果均较差;以高炉灰焦粒、活化沸石、椰壳生物炭、陶粒、活性炭作为滤料的5种过滤模块均能有效提高初期雨水中COD、NH₄ ⁺-N、TN和TP的去除效果;其中陶粒在达到理想的脱氮除磷效果的同时,也可实现较好的SS和COD去除效果,使用年限与其他过滤模块相差不大,且售价（5~13元/kg）略低于其他过滤模块。

     

滤筒除尘器不同进出口夹角对气流分布的影响

针对滤筒除尘器不同进出口夹角对除尘器内部流场的影响进行模拟研究。首先对除尘器进行适当简化和假设,建立起适合有限元计算的数值模型,通过流体力学分析软件Fluent对不同进出口夹角下的滤筒除尘器的气流分布进行模拟。根据模拟结果综合考虑,进出口夹角为180°时气流分布最均匀,除尘器内部流场最好。     

Ecological Feasibility Studies in Restoration Decision Making

The restoration of degraded systems is essential for maintaining the provision of valuable ecosystem services, including the maintenance of aesthetic values. However, restoration projects often fail to reach desired goals for a variety of ecologic, financial, and social reasons. Feasibility studies that evaluate whether a restoration effort should even be attempted can enhance restoration success by highlighting potential pitfalls and gaps in knowledge before the design phase of a restoration. Feasibility studies also can bring stakeholders together before a restoration project is designed to discuss potential disagreements. For these reasons, a feasibility study was conducted to evaluate the efficacy of restoring a tidal freshwater marsh in the Potomac River near Alexandria, Virginia. The study focused on science rather than engineering questions, and thus differed in approach from other feasibility studies that are mostly engineering driven. The authors report the framework they used to conduct a feasibility study to inform other potential restoration projects with similar goals. The seven steps of the framework encompass (1) initiation of a feasibility study, (2) compilation of existing data, (3) collection of current site information, (4) examination of case studies, (5) synthesis of information in a handbook, (6) meeting with selected stakeholders, and (7) evaluation of meeting outcomes. By conducting a feasibility study using the seven-step framework, the authors set the stage for conducting future compliance studies and enhancing the chance of a successful restoration.     

潮汐河网可降解有机物降解系数研究

潮汐河网具有其独特的水物理及水化学特性。本文采用珠江三角洲河网区域20个水样的BOD降解实验数据,并用BOD反应一级动力学方程进行数据拟合,结果表明,潮汐河网水体BOD降解过程的延滞期消失,远离污染源河段河水的BOD降解过程两阶段区分不明显,降解过程符合BOD反应一级动力学方程。此外,潮汐河网河水的降解系数随时间的变化过程是随机的。      

潮汐河网调水工程的环境与经济效益分析——以北江、西江调水工程为例

本文针对潮汐河网的基本特点,提出了运用非恒定流水环境实时数学模型和“影子工程法"对一系列引水方案的环境与经济效益进行定量的预测、分析和比较。该方法对潮汐河网地区水务工程的环境与费用效益分析研究具有普遍的参考意义。文中的算例为广州市市政洪水与污水整治战略决策提供了科学的依据。      

Health and safety implications of alternative energy technologies. II. Solar

No energy technology is risk free when all aspects of its utilization are taken into account. Every energy technology has some attendant direct and indirect health and safety concerns. Solar technologies examined in this paper are wind, ocean thermal energy gradients, passive, photovoltaic, satellite power systems, low- and high-temperature collectors, and central power stations, as well as tidal power. For many of these technologies, insufficient historical data are available from which to assess the health risks and environmental impacts. However, their similarities to other projects make certain predictions possible. For example, anticipated problems in worker safety in constructing ocean thermal energy conversion systems will be similar to those associated with other large-scale construction projects, like deep-sea oil drilling platforms. Occupational hazards associated with photovoltaic plant operation would be those associated with normal electricity generation, although for workers involved in the actual production of photovoltaic materials, there is some concern for the toxic effects of the materials used, including silicon, cadmium, and gallium arsenide.Satellite power systems have several unique risks. These include the effects of long-term space travel for construction workers, effects on the ozone layer and the attendant risk of skin cancer in the general public, and the as-yet-undetermined effects of long-term, low-level microwave exposure. Hazards may arise from three sources in solar heating and cooling systems: water contamination from corrosion inhibitors, heat transfer fluids, and bactericides; collector over-heating, fires, and out-gassing and handling and disposal of system fluids and wastes. Similar concerns exist for solar thermal power systems. Even passive solar systems may increase indoor exposure levels to various air pollutants and toxic substances, eitherdirectly from the solar system itself or indirectly by trapping released pollutants from furnishings, building materials, and indoor combustion.Operated by Union Carbide Corporation under contract W-7405-eng-26 for the U.S. Department of Energy.     

Reintroduction of eelgrass (Zostera marina) in the Dutch Wadden Sea; review of research and suggestions for management measures

Eelgrass (Zostera marina L.) in the Dutch Wadden Sea historically covered an area varying from 65–150 km² in the eulittoral as well as the sublittoral zones. At present, this area comprises less than 1 km² eulittoral eelgrass stands, with an associated decrease in habitat diversity. The causes for this decline are presumably connected with the ‘wasting disease’ and the closure of the former Zuiderzee in the early 1930s resulting in increased tidal range and increased currents. After a slight recovery of the eelgrass populations on the intertidal flats a definite decline started in the early 1970s, possibly connected to increased turbidity. The present water quality and turbidity do not negatively influence eelgrass growth up to a depth of at least 0.6m below Mean Sea Level. Based on mesocosm experiments and field experiments it is concluded that re-establishment of eelgrass should be possible in sheltered bays and on unexposed tidal flats. The most suitable depths for a reintroduction are those between 0 and 20–40 cm below mean sea level.     

Reintroduction of eelgrass ( Zostera marina ) in the Dutch Wadden Sea; Review of research and suggestions for management measures

Eelgras (Zostera marina L.) in the Dutch Wadden Sea historically covered an area varying from 65–150 km² in the eulittoral as well as the sublittoral zones. At present, this area comprises less than 1 km² eulittoral eelgrass stands, with an associated decrease in habitat diversity. The causes for this decline are presumably connected with the ‘wasting disease’ and the closure of the former Zuiderzee in the early 1930s resulting in increased tidal range and increased currents. After a slight recovery of the eelgrass populations on the intertidal flats a definite decline started in the early 1970s, possibly connected to increased turbidity. The present water quality and turbidity do not negatively influence eelgrass growth up to a depth of at least 0.6m below Mean Sea Level. Based on mesocosm experiments and field experiments it is concluded that re-establishment of eelgrass should be possible in sheltered bays and on unexposed tidal falts. The most suitable depths for a reintroduction are those between 0 and 20–40 cm below mean sea level.     

入口位置对多入口旋风分离器性能的影响

对称多入口结构有助于提高旋风分离器的性能,但入口位置的选择尚无明确的规范.在Lapple型旋风分离器的基础上,设计了4种不同入口位置的四入口旋风分离器,并采用数值模拟方法研究了入口位置对于其流场和分离性能的影响.结果表明:当入口在径向外侧时,切向速度能够保持稳定,短路流量占比较低,此时压降较低,分离效率较高;而当入口在...