Plants as river system engineers

Plants growing within river corridors both affect and respond to fluvial processes. Their above‐ground biomass modifies the flow field and retains sediment, whereas their below‐ground biomass affects the hydraulic and mechanical properties of the substrate and consequently the moisture regime and erosion susceptibility of the land surface. This paper reviews research that dates back to the 1950s on the geomorphological influence of vegetation within fluvial systems. During the late twentieth century this research was largely pursued through field observations, but during the early years of the twenty‐first century, complementary field, flume and theoretical/modelling investigations have contributed to major advances in understanding the influence of plants on fluvial systems. Flume experiments have demonstrated the fundamental role of vegetation in determining river planform, particularly transitions from multi‐ to single‐thread forms, and have provided insights into flow–vegetation–sediment feedbacks and landform building, including processes such as channel blockage and avulsion. At the same time, modellers have incorporated factors such as moisture‐dependent plant growth, canopy and root architecture and their influence on flow resistance and sediment/bank reinforcement into morphodynamic models. Meanwhile, field investigations have revealed that vegetation has a far more important and complex influence on fluvial systems than previously realized. It is now apparent that the influence of plants on river systems is significant across space scales from individual plants to entire forested river corridors. Small plant‐scale phenomena structure patch‐scale geomorphological forms and processes, and interactions between patches are almost certainly crucial to larger‐scale and longer‐term geomorphological phenomena. The influence of plants also varies continuously through time as above‐ and below‐ground biomass change within the annual growth cycle, over longer‐term growth trajectories, and in response to external drivers of change such as climatic, hydrological and fluvial fluctuations and extremes. Copyright © 2013 John Wiley & Sons, Ltd.     

Dispersion of Flue Gases from Power Plants in Brunei Darussalam

— A series of mathematical and computer models describing alternative methods for the disposal of flue gases emitted from coal and gas fired power plants is discussed. Brunei Darussalam has three gas-fired power plants using approximately 3.106 m³/day gas and emitting substantial flue gases into the atmosphere. After desulphurisation with sea water, carbon-dioxide, the gas primarily associated with global warming and the main constituent of flue gas, can be dissolved under pressure in seawater and injected into the sea at suitable depth. The injected solution constitutes a negatively buoyant plume in the sea, carried by currents to deeper regions. It has been noted that the solution mixes and reacts with other oceanic components and converts to carbonates and sulphates that can remain near the bottom for several hundreds of years. Until a better alternative is developed, this may be an immediate solution to the problem of dealing with flue gases. The feasibility and economics of this alternative have been discussed in the literature. For optimal design criteria for such disposal, numerous parameters (such as location, pipe diameter, type of diffuser, angles of discharge, etc.) are involved in the mathematical analysis. Many alternative sets of these parameters must be used as input parameters to arrive at final design parameters for optimal results.     

Studying Thermal Eutrophication in Cooling Reservoirs of Nuclear Power Plants

The processes of thermal eutrophication of the cooling reservoirs of the Smolensk and Kursk nuclear power plants (NPP) were studied. Data characterizing changes in the concentrations of inorganic forms of nitrogen and phosphates in water during its heating in the NPP cooling system were obtained. Different aspects of the effect of heated water on the production–destruction processes are discussed. The conditions under which the intensity of thermal eutrophication can substantially increase were determined.     

湿地中碱性磷酸酶的动力学特征与水生植物的关系

本文讨论了种植菹草 (PotamogetoncrispusL .)、水花生 (AlternanthearphiloxeroidesGriseb .)、紫背浮萍 (Spirodelapolyrhiza(L .)Schleid .)以及对照实验池 (12 .5m× 9.5m)过滤 (小于0 4 5 μm)与未过滤水样和沉积物中碱性磷酸酶的动力学特征及其分布 .水生植被能降低水样和表层沉积物酶的催化效率 ,抑制作用因植物的种类而异 ,且在未过滤水中表现得尤为突出 .因此 ,受抑制者多与较大的颗粒相联系 ,这一结果暗示植物克藻效应的胞外酶学机制 .水生植物种植区表层沉积物的低酶活性是其中有机磷不易矿化故得以保持从而改善水质的可能原因 ,而深层沉积物酶的反应速度则明显高于对照 .湿地亚表层沉积物因其具有的理论与实际意义而值得深入研究     

Diisopropanolamine Biodegradation Potential at Sour Gas Plants

The potential for aerobic and anaerobic biodegradation of a sour gas treatment chemical, diisopropanolamine (DIPA), was studied using contaminated aquifer materials from three sour gas treatment sites in western Canada. DIPA was found to be readily consumed under aerobic conditions at 8°C and 28°C in shake flask cultures incubated with aquifer material from each of the sites, and this removal was characterized by first-order kinetics. In addition, DIPA biodegradation was found to occur under nitrate-, Min(IV)., and Fe(III)-reducing conditions at 28°C, and in some cases at 8°C, in laboratory microcosms, DIPA loss corresponded to consumption of nitrate, and production of Mn(II) and Fe(II) in viable microcosms compared to corresponding sterile controls. A threshold DIPA concentration near 40 mg/L was observed in the anaerobic microcosms. This report provides the first evidence that DIPA is biodegraded under anaerobic conditions, and our data suggest that biodegradation may contribute to DIPA attenuation under aerobic and anaerobic conditions in aquifers contaminated with this sour gas treatment chemical.     

Experimental Study of the Distribution Function of Water Residence Time in Disinfection Plants

A hydraulic system for testing water disinfection plants is described. A method for determining the residence time distribution function from tracer experiments is suggested. The effect of tracer injection mode and the plant construction on residence time distribution function is investigated.     

Full‐scale Applications of Membrane Filtration in Municipal Wastewater Treatment Plants

The performance of one pilot‐scale and two full‐scale membrane bioreactors (MBR) were evaluated based on the control of main operational parameters, composition of microbial community and pathogens concentration in the treated outlet. Plants were designed for 0.75 m³/day (A), 60 m³/day (B) and 30 m³/day (C). Inlet and outlet samples were monitored for chemical oxygen demand (COD), biological oxygen demand, total suspended solids, ammonia nitrogen concentration (NH₄–N), nitrate nitrogen concentration, total Kjeldahl nitrogen, total phosphorus and phosphate phosphorus concentration concentrations. Plants showed good COD removal: 91.9% for Plant A, 97.8% for Plant B and 94.2% for Plant C. The targeted nitrogenous ion was NH₄–N due to the requirements for outlet limits. NH₄–N removal was moderate for Plant A (73.3%) and Plant B (86.1%) and excellent for Plant C (>99%). Excellent phosphorus removal was achieved by Plant A (average outlet concentration was 0.7 mg/L, efficiency 84.7%). Unsatisfactory results for phosphorus removal were achieved at the full‐scale plants due to operational problems. The dependency between the extracellular polymeric substances increase and decreasing mixed liquor volatile suspended solids for both lab and full‐scale plants was confirmed. Soluble microbial product concentrations were reduced by 65–68% after coagulant dosage for Plant A. Outlets from the MBR plants were monitored for the presence of pathogens (thermotolerant coliforms, Escherichia coli, intestinal Enterococci and culturable microorganisms at 22 and 37°C). The treated effluent from Plant A, B and C met Czech national legislation regarding reuse criteria (standards) for environment, irrigation and swimming purposes. Plants B and C were not able to achieve requirements for potable water and personal hygiene quality standards.     

Occurrence of Phthalates in Sewage Sludge from Three Wastewater Treatment Plants in Istanbul,Turkey

Phthalates are considered priority pollutants because of their potential adverse effects on ecosystems and human health. The objectives of this study were to determine the occurrence of five phthalates (DMP, DEP, DBP, BBP, and DEHP) in sewage sludge and to determine the seasonal variability of these contaminants at three (Bahçe?ehir, Pa?aköy, and Tuzla) full‐scale municipal and domestic wastewater treatment plants (WWTP) in Istanbul, Turkey. Mass balance was also calculated for DEHP at Tuzla WWTP sludge treatment units. DMP, DEP, DBP, BBP, and DEHP concentrations in sewage sludge ranged from 1.4 to 2.7 mg/kg dry weight (dw), 1.1 to 2.8, 0.6 to 4.6, 2.8 to 6.2, 18 to 490 mg/kg dw, respectively. Phthalate concentrations from the Bahçe?ehir and Pa?aköy WWTPs met the limit (100 mg/kg dw) of Turkey national sludge regulation and the Europe Union draft of sludge directive for land application, whereas phthalate concentrations from Tuzla WWTP exceeded the maximum permissible concentration. Phthalate concentrations did not show seasonal variations for Bahçe?ehir and Pa?aköy WWTPs, which receive mainly household wastewater while some fluctuations were observed DEP, DBP, and DEHP at Tuzla WWTP which has a lot of industrial wastewater contribution. The mass balance showed that approximately 17% of DEHP in the primary and secondary sludge was removed by anaerobic digestion, while 43% returned back to the beginning of the WWTP and 40% remained in the dewatered sludge. This study suggests that phthalates in sludge from WWTPs with industrial wastewater contribution may limit the use of sludge for land application.     

Plants as river system engineers: further comments

This paper is a response to commentary on the review by Gurnell (Plants as river system engineers. Earth Surface Processes and Landforms 39 : 4–25, 2014). It covers three themes. First, it explains how the review focused on physical ecosystem engineering by plants, particularly in the northern humid temperate zone. Second, it explains how the review was structured to address that theme and why annual species were not highlighted. Within the humid temperate zone, mature plants of annual species are not present during the seasons of the year when fluvial processes are most active: they survive as seeds or young seedlings, and so their ability to act as river ecosystem engineers is limited. Third, some comments are made regarding the annual species, Himalayan balsam (Impatiens glandulifera), including the traits that enable it to be successful in riparian environments, its competitive ability, its potential role in influencing fluvial sediment dynamics, and the need for controlled experiments to characterize and quantify the latter over one or more complete years. Copyright © 2014 John Wiley & Sons, Ltd.     

滆湖水生植物生物量、演替规律及合理利用

用五种不同的方法估算了滆湖水生植物的生物量,比较分析了全湖断面生物量和群丛生物量.分三个方面对滆湖水生植物的演替规律进行了讨论,对草型湖泊水生植物的合理利用进行了探讨.初步提出了草型湖泊估算渔产潜力的公式.在分析引起水生植物生物量变化的原因的基础上,提出了若干合理利用植物资源的建议.     

Improving the Efficiency of Wastewater Biological Treatment at Chemical Plants

The potential for improving the efficiency of wastewater biological treatment by using carbonate slime (heat power engineering waste) as a secondary material resource is illustrated by the case of Kazan Synthetic Rubber Works. The details of interaction between carbonate slime and activated-sludge microorganisms with inorganic components of plant wastewater are considered. The authors came to the conclusion that adsorption material should be used and developed a process flow chart for wastewater biosorption treatment.     

Study on Site Specific Design Earthquake Ground Motion of Nuclear Power Plants in China

The main technical backgrounds and requirements are introduced with regard to earthquake ground motion design parameters in several domestic and American standards, codes and guides involved in the seismic analysis and design activities of nuclear power plants in China. Based on the research results from site seismic safety evaluation of domestic nuclear power plant projects in the last years, characteristics and differences of site specific design spectra are analyzed in comparison with standard response spectra, and the suitability of standard response spectra for domestic nuclear power plant projects is discussed.     

滆湖水生植物生物量、演替规律及合理利用

用五种不同的方法估算了滆湖水生植物的生物量,比较分析了全湖断面生物量和群丛生物量．分三个方面对滆湖水生植物的演替规律进行了讨论,对草型湖泊水生植物的合理利用进行了探讨．初步提出了草型湖泊估算渔产潜力的公式．在分析引起水生植物生物量变化的原因的基础上,提出了若干合理利用植物资源的建议．     

核电结构PCS水箱液动压力分析等效模型

中国核电厂抗震设计规范推荐采用的Housner模型不适用于复杂形状核电储液结构的流固耦合分析。对于AP1000和CAP1400核电站屏蔽厂房顶部非能动安全壳冷却系统重力水箱(简称PCS水箱),基于圆柱形水箱的Housner等效质量-弹簧模型,通过引入水箱体积修正参数,提出PCS水箱的三维等效质量-弹簧模型。采用有限元软件ADINA建立水箱结构流固耦合整体有限元模型以进行模态分析,计算分析PCS水箱和对应环形水箱在不同尺寸和液体深度条件下的液体晃动自振特性。对比整体有限元模型与三维等效质量-弹簧模型计算结果发现,提出的PCS水箱三维等效质量-弹簧模型能给出其内液体晃动各阶振型的液动压力合理估计值,适用于具有复杂形状的PCS水箱液动压力分析。本文的等效模型方法可推广应用于其他复杂形状水箱的液动压力分析。     

我国核电厂厂址特定地震动特征分析

本文介绍了我国核电厂地震安全性评价及抗震设计中涉及的法规、标准和导则中关于设计地震动参数确定的技术背景和要求.基于近些年来我国开展的核电厂厂址可行性研究阶段地震安全性评价工作的结果,分析了一些潜在厂址特定地震动反应谱特征及其与规范标准反应谱的差异,探讨了规范反应谱对我国核电厂工程的适用性问题.