TRANSPORT OF BICOMPONENT CONTAMINANT IN FREE-SURFACE WETLAND FLOW

This paper presents a theoretical analysis of a pulsed bicomponent contaminant emission into a free-surface wetland flow.The basic equations are for the bicomponent contaminant transport in the wetland flow under the combined action of advection,mass dispersion,and ecological reaction at the phase averaged scale.The effect of the ecological reaction is separated from the hydro-dynamic effect via a set of widely used transforms.The analytical solution for the evolution of the depth-averaged concentration is rigorously derived,with a limiting case covering the known solution for the single component contaminant transport.It is found that the depth-averaged species concentration of the bicomponent contaminant can approach an equilibrium state determined by the distri-bution coefficient.     

陕西电网建设抽水蓄能电站的初步探讨

抽水蓄能电站在电力系统中具有调峰填谷、调频、事故备用和黑启动等多种功能,成为现代电力系统中有效的调节工具。文章结合陕西电网规划期调峰能力研究成果,对陕西电网建设抽水蓄能电站进行了初步探讨。     

天津滨海新区湿地生态恢复需水量评估

生态需水量的核算是湿地水文生态恢复的关键步骤。通过分析计算,评估天津滨海新区湿地生态系统各类生态需水的3个特征值:最低生态需水量(即湿地生态系统丧失生态功能的临界需水量)、最适生态需水量(即维持湿地生态功能最佳状态的需水量)、最高生态需水量(即湿地生态系统所能承受的最大水量),得出如下结论:天津滨海地区湿地的生态需水主要包括蒸发蒸散需水量、湿地土壤需水量、补给地下水、湿地生物栖息地需水量4个部分;湿地的最低生态需水量为177.68×106～276.85×106 m3,最适生态需水量539.23×106～807.81×106 m3,最高生态需水量1 206.55×106～1 409.02×106 m3。     

Climate adaptation in ‘new world’ cultural landscapes: The case of Bay of Fundy agricultural dykelands (Nova Scotia,Canada)

North America has few cultural agricultural landscapes, and often commensurately poor governance arrangements for managing change in such settings. This research uses the Acadian dykelands of Nova Scotia, Canada, as an opportunity to explore the social and governance limits to coastal climate adaptation in ‘new world’ cultural agricultural landscapes, as well as inform local decision-making. Approximately half of Nova Scotia’s coastal wetlands were converted to dykeland in the 1600s, lowering local resilience to the increased frequency and storm severity anticipated with climate change. Today, dykelands protect a diversity of public and private interests, meanings and values, yet are controlled by the agricultural sector, which can no longer afford to maintain them all to 2050 climate projections. We report here on a representative online Q-methodology survey of 183 adult Nova Scotians in the spring of 2015. Respondents sorted 34 statements along a normal distribution about whether they prefer dykeland maintenance or wetland restoration, and under what governance arrangements. Four factors were derived: the dominant discourse was local, female and strongly pro-dykeland, indicating the likelihood for local resistance to dykeland removal on for cultural, recreational and farming reasons. The second factor was supportive of wetland restoration for reasons of efficiency, not wetland affinity, but characterized by those in positions of management power. The two minority viewpoints were less informed about dykelands, characteristic of outsiders, and concerned more with governance. More education is needed about the challenges facing dykelands, the benefits of coastal wetlands, and the management options, but this research shows proposals to change landscape should emphasize flood mitigation over cost-saving. Cultural values and status quo bias are clearly barriers to adaptation planning, even when discussing the removal of man-made structures. The factors were surprisingly polarized, suggesting the forced-normal distribution affects the space available to convey nuanced perspectives. Large p-set Q-method of this kind is likely most useful for characterizing the emergent discourses demographically, and understanding their prevalence; the same discourses had emerged within a much smaller pilot study.     

Carbon and energy prices under uncertainty: A theoretical analysis of fuel switching with heterogenous power plants

European power producers have a major influence on the EU ETS, given that both their CO₂ emissions and their EUA (European Union Allowance) allocations account for more than half of the total volumes of the scheme. Fuel switching is often considered as the main short-term abatement measure under the EU ETS. It consists in substituting combined cycle gas turbines (CCGTs) for hard-coal plants in power generation. Thereby coal plants run for shorter periods, and CO₂ emissions are reduced. This paper provides the first theoretical analysis of fuel switching, in a context where power plants involved are not equally efficient. We begin with a preliminary work using illustrative examples and sensitivity analyses, which enables us to observe how differences in the efficiency of power plants impact the cost of fuel switching, and how this is related to the level of switching effort. Based on this, we build a theoretical model taking into account the effect of differences in the efficiency of power plants involved in fuel switching. We also investigate the effect of the timing of fuel switching abatements, within the temporally defined environment of our dynamic model. Results demonstrate that the gas price and uncontrolled CO₂ emissions act together on the carbon price. We show that the influence of the gas price on the carbon price depends on the level of uncontrolled CO₂ emissions, due to heterogeneity of power plants that are used in the fuel switching process. Furthermore, we show that the time of occurrence of uncontrolled emissions matters so that shocks have a stronger impact when they occur in a period that is closed to the end of the phase.     

Impacts of land-cover change on the water flow regulation ecosystem service: Invasive alien plants,fire and their policy implications

Land and water resource issues typically fall under separate governance systems. For example, agricultural policy regulates land-cover change while water departments regulate water quality. However, land-use changes can directly affect water resources. Water flow regulation is a key service which is affected by changes in land-cover but its dynamics are poorly understood by most policy makers and land management organisations. We simulated and quantified the effects of plant invasions on land-cover, hydrological soil characteristics and catchment responsiveness on flow regulation using a hydrological model. The case study was located in the indigenous fynbos shrublands in South Africa. Fynbos requires fire to regenerate, has moderate biomass, occurs mostly in areas with a potential to erode and is prone to invasion by woody plant species, particularly trees. Invasions can affect flow regulation by changing community structure and function and increasing fuel loads. The greater fuel load increases fire intensity and severity which, in turn, changes the hydrological responses of catchments. Few studies have assessed the effects of invasion on hydrological responses but studies on plantations have recorded significant increases in soil water repellence following fire, resulting in increased overland flow similar to impacts of fires in invaded areas. Simulation of clear-felling of pines and different degrees of water repellency increased both the responsiveness of the catchment to rainfall and extreme rainfall events. The simulated fire effects were consistent with other studies of hydrological responses to fire. Our study indicates that invasions of pines and acacias in the study area could substantially increase the risk of flood damage even from moderate rainfall events, and highlights the importance of maintaining flow regulation capacity. New policy approaches are required which take account of the linkages and interactions between land-use choices, water resources and ecosystem services, and address them when considering governance arrangements.     

Devising an electronically supported heritage conservation method for the Valley of Flowers in the Indian Himalayas

The Valley of Flowers is a national park in the Himalayan state of Uttarakhand in India that was classified as a world natural heritage site in 1988. Around 1982, its maximum carrying capacity was fixed at 60 persons per day, which has been called excessive by experts and observers, given the extremely fragile and immensely valuable nature of the Valley's heritage. This, in monetary terms, can be put at millions of dollars, and is considerably more viewed in terms of knowledge of breeding medicinal plants in cold climates that are being affected by climate change, which its microclimate and ecology present. Given the state's poor resources and the fact that tourism is one of the most important industries for development and conservation, this research assesses the heritage value of the Valley and develops a programme for conservation, including a computerised program for permits, whose value can easily be raised from the current paltry Rs 150 per person. Accompanied by fallow periods and marketing through the Internet to aim for educated tourists, the program ensures that the maximum carrying capacity of the Valley is never exceeded, thus spreading out the number of tourists over its 3.5-month season, while allowing flexibility in booking for chance groups and small families that can pay more.     

陕西黄河湿地生态问题及保护初探

陕西黄河湿地是由黄河及其支流渭河、洛河三条河流交汇而形成的,交汇处主要以河床漫滩为主,由河流水面、江心洲、滩涂、泛洪平原及部分低阶地组成,是典型的河流湿地。近年来随着周边经济的发展,人类开发利用湿地的强度越来越大,湿地生态系统及其功能退化明显。因此研究和保护这一湿地,对区域生态环境的建设有着重大意义。本文将河流湿地开发利用过程中出现的问题进行了分析,针对水资源减少、生物多样性锐减和环境污染等问题提出了一些开发与保护措施。     

吉林省柳河县湿地利用与保护

从湿地类型、面积及其比例构成等方面介绍了吉林省柳河县湿地资源现状与基本特征;分析了湿地面积的动态变化及其原因;探讨了涅地资源变化特点及其未来发展趋势.认为湿地资源的利用率和生产力较低、湿地自然保护区建设缓慢以及泥炭地开发利用过度等方面,是目前柳河县湿地利用与保护中所存在的主要问题;在此基础上,提出实施柳河县湿地生态保护...     

1983-2006年南四湖湿地植被动态变化研究

采用实地调查和实验分析,结合遥感和地理信息系统技术,研究南四湖湿地在1983-2006年浮游植物和水生维管束植物的种类、分布和生物量变化.结果表明,1983-2006年,南四湖湿地植被生物量整体呈下降趋势,反映了人类的围垦、养殖等活动造成湿地初级生产力的降低,并且这种影响由湖泊外围向湖心弱化,对外围湿地的影响最大.