旅游干扰对纳帕海湖滨草甸湿地土壤水文调蓄功能的影响

在野外调查和室内分析的基础上,研究了旅游干扰对纳帕海湖滨草甸湿地土壤蓄水功能和水文调节能力的影响。结果表明,旅游干扰对草甸湿地表层土壤环境的破坏作用显著。随着旅游干扰强度增加,草甸湿地0～20cm表层土壤容重显著增加,孔隙度减小,土壤持水能力急剧下降,以未受旅游干扰作为参照,在轻度、中度和重度干扰下草甸表层土壤饱和持水能力分别下降了10%、48%和75%,表明土壤蓄水功能在高强度旅游干扰作用下退化显著。未受旅游干扰区草甸湿地土壤有效调蓄水空间、非毛管孔隙度、初渗速率和稳渗速率分别为1897g/kg、44%、3.14mm/min和1.92mm/min,在重度干扰作用下分别下降了77%、43%、94%和96%,高强度旅游干扰作用下草甸湿地土壤水文调蓄功能显著退化。     

Relating accretion and erosion at an exposed tidal wetland to the bottom shear stress of combined current-wave action

Sediment dynamics have an important influence on the morphological evolution of tidal wetlands, which consist of mudflats and salt marshes. To understand the nature of sediment behavior under combined current-wave action at an exposed tidal wetland, we measured the waves, currents, water depths, bed-level changes, and sediment properties at a mudflat-salt marsh transition on the Yangtze Delta, China, during five consecutive tides under onshore winds of ~ 8 m/s, and calculated the bed shear stresses due to currents (τ_c), waves (τ_w), combined current-wave action (τ_cw), and the critical shear stress for erosion of the bottom sediment (τ_ce). The bed shear stresses under combined current-wave action (τ_cw) were approximately five times higher on the mudflat (up to 1.11 N/m²; average 0.27 N/m²) than on the salt marsh (up to 0.14 N/m²; average, 0.06 N/m²). On the mudflat, τ_cw was larger than the critical erosion shear stress (τ_ce = 0.103 N/m²) for 70% of the period of submergence, whereas τ_cw was always lower than τ_ce at the salt marsh site (τ_ce = 0.116 N/m²). This result indicates that the sediment dynamics on the mudflat were dominated by erosion, whereas at the salt marsh they were governed by deposition, which is in agreement with the observed bed-level change during the study period (− 3.3 mm/tide on the mudflat and 3.0 mm/tide on the salt marsh). A comparison of τ_cw values calculated using the [van Rijn, 1993] and [Soulsby, 1995] models for bed shear stresses under combined current-wave action indicates that both models are applicable to the present case and effectively predict the bottom shear stress under combined current-wave action. Overall, we conclude that τ_cw in combination with τ_ce is useful in assessing the hydrodynamic mechanisms that underlie the morphological evolution of exposed tidal wetlands.     

基于模型集成的北京湿地价值评价系统设计与实现

湿地价值评价让公众和管理者很直观了解湿地功能及价值大小,对于湿地保护宣传和湿地管理都有着重要的意义。本文在北京湿地的大气调节、气候调节、蓄水调洪、水质净化、地下水补给、控制土壤侵蚀、生物多样性、滞尘、生物产品、水源供给、文化遗产和旅游休憩等12项价值评价方法研究基础上,利用ArcGIS Model Builder等多种建模方式,构建了12项湿地价值评价模型,并基于ArcGIS Engine二次开发组件,在.NET环境下设计和实现了北京湿地价值评价系统。结果表明:(1)先建立模型及工具集,然后进行统一封装和调用,最后开发应用系统,这种湿地价值评价系统设计与开发方式快速简单、容易实现、而且稳定可靠;(2)该系统可以有效管理湿地资源数据,方便快捷地完成湿地资源各项功能价值评价和综合价值测算,快速获得北京湿地的各个湿地斑块、各种类型湿地、各行政区县和任何统计单元的湿地单项功能价值和综合功能价值量,还可以快速编制湿地价值空间图和统计报表;(3)该系统为湿地价值评价提供了一种自动化、流程化、标准化的测量方法,具有一定的推广潜力。     

Impact of climate change on wetland ecosystems: A critical review of experimental wetlands

Climate change is identified as a major threat to wetlands. Altered hydrology and rising temperature can change the biogeochemistry and function of a wetland to the degree that some important services might be turned into disservices. This means that they will, for example, no longer provide a water purification service and adversely they may start to decompose and release nutrients to the surface water. Moreover, a higher rate of decomposition than primary production (photosynthesis) may lead to a shift of their function from being a sink of carbon to a source. This review paper assesses the potential response of natural wetlands (peatlands) and constructed wetlands to climate change in terms of gas emission and nutrients release. In addition, the impact of key climatic factors such as temperature and water availability on wetlands has been reviewed. The authors identified the methodological gaps and weaknesses in the literature and then introduced a new framework for conducting a comprehensive mesocosm experiment to address the existing gaps in literature to support future climate change research on wetland ecosystems. In the future, higher temperatures resulting in drought might shift the role of both constructed wetland and peatland from a sink to a source of carbon. However, higher temperatures accompanied by more precipitation can promote photosynthesis to a degree that might exceed the respiration and maintain the carbon sink role of the wetland. There might be a critical water level at which the wetland can preserve most of its services. In order to find that level, a study of the key factors of climate change and their interactions using an appropriate experimental method is necessary. Some contradictory results of past experiments can be associated with different methodologies, designs, time periods, climates, and natural variability. Hence a long-term simulation of climate change for wetlands according to the proposed framework is recommended. This framework provides relatively more accurate and realistic simulations, valid comparative results, comprehensive understanding and supports coordination between researchers. This can help to find a sustainable management strategy for wetlands to be resilient to climate change.     

南四湖湿地遥感信息分区分层提取研究

该文以南四湖区为试验区,利用TM数据,在对各地类光谱特征进行系统分析的基础上,提出了分区和分层相结合的湿地信息提取技术方法。根据研究区各种湿地类型的空间分布特点,将该区分为两个湿地类型区;在每一个区内,根据湿地的光谱特征进行分层提取,采用单红外波段阈值法、模型法以及改进的监督分类等技术方法。结果显示,该区湿地有14类,其中,自然湿地91119 51hm2,人工湿地122243 13hm2。     

长江大型通江湖泊中克氏原鳌虾(Procambarus clarkii)种群数量的影响因子

入侵物种和栖息地退化都是导致淡水生物多样性丧失的主要原因。但是关于栖息地退化和入侵物种种群数量的研究很少。克氏原鳌虾(Procambarus clarkii)是淡水生态系统中最具破坏性的入侵物种之一。本研究采用主成分分析法(Principal Component Analysis,PCA)、广义线性模型(Generalized Linear Model,GLM)和贝叶斯模型(Bayesian model),分析了2017-2019年西洞庭湖天然湿地和改造湿地中的克氏原鳌虾的单位捕捞努力量渔获量(CPUE)与环境因子的关系。研究结果表明,克氏原鳌虾CPUE与总氮、总磷、水温、pH、水深、水透明度呈正相关,与溶解氧和氧化还原电位呈负相关。克氏原鳌虾CPUE在天然湿地和改造湿地中的差异不显著。克氏原鳌虾CPUE呈逐年下降趋势,且2018年与2019年的克氏原鳌虾CPUE均显著低于2017年。水文情势的年际变化对克氏原鳌虾种群数量的影响起重要作用。保证夏季水位和流速对控制克氏原鳌虾种群数量具有重要意义。     

Determination of the health of Lunyangwa wetland using Wetland Classification and Risk Assessment Index

Wetlands are major sources of various ecological goods and services including storage and distribution of water in space and time which help in ensuring the availability of surface and groundwater throughout the year. However, there still remains a poor understanding of the range of values of water quality parameters that occur in wetlands either in its impacted state or under natural conditions. It was thus imperative to determine the health of Lunyangwa wetland in Mzuzu City in Malawi in order to classify and determine its state. This study used the Escom's Wetland Classification and Risk Assessment Index Field Guide to determine the overall characteristics of Lunyangwa wetland and to calculate its combined Wetland Index Score. Data on site information, field measurements (i.e. EC, pH, temperature and DO) and physical characteristics of Lunyangwa wetland were collected from March, 2013 to February, 2014. Results indicate that Lunyangwa wetland is a largely open water zone which is dominated by free-floating plants on the water surface, beneath surface and emergent in substrate. Furthermore, the wetland can be classified as of a C ecological category (score = 60–80%), which has been moderately modified with moderate risks of the losses and changes occurring in the natural habitat and biota in the wetland. It was observed that the moderate modification and risk were largely because of industrial, agricultural, urban/social catchment stressors on the wetland. This study recommends an integrated and sustainable management approach coupled with continuous monitoring and evaluation of the health of the wetland for all stakeholders in Mzuzu City. This would help to maintain the health of Lunyangwa wetland which is currently at risk of being further modified due to the identified catchment stressors.     

盐度对芦苇(Phragmites australis)表流湿地除氮效果的影响

利用芦苇湿地去除农业污水中的氮是博斯腾湖流域控制富营养化的重要手段.但是,污水中的盐分往往会抑制芦苇(Phragmites australis)湿地的除氮效果.为了探索不同盐度对芦苇湿地脱氮效果的影响和机制,研究4个不同的盐度梯度(淡水、2‰、5‰和10‰)对芦苇表流湿地中氮去除的影响,测定不同盐度下湿地表层(0~10.0 cm)和下层土壤(10.0~20.0 cm)中硝化、反硝化作用强度的变化.结果表明,盐度上升显著降低了湿地氮的去除率,但是不同离子形态的氮变化趋势并不一致.5‰和10‰盐度下的芦苇湿地中总氮、铵态氮去除率分别下降了9.03%、31.80%和23.10%、39.20%,亚硝态氮累积率分别上升了190%、690%,而硝态氮并未发生明显变化.相对于参与反硝化作用的菌群,盐度对参与硝化作用菌群的抑制作用更强是产生此现象的主要原因.除此之外,盐度升高导致植物根系泌氧减少也是土壤中的硝化作用强度降低的重要原因之一.     

湿地边界确定研究进展

本文分析了目前湿地边界确定存在的困难及各种湿地边界指标及其标准在湿地边界确 定过程中存在的问题, 将系统论的基本原理与自然地理学相结合, 分析了湿地系统与陆地系统和 水体系统之间本质特征的区别, 认为: 由于湿地边界存在的客观性, 湿地边界确定的困难并不能 说明其边界就不能确定; 用人为"规定"的标准来确定湿地的边界是不科学的, 任何自然综合体的 边界只能认识而不是人为规定的; 由于湿地多样性, 从湿地本身特征无法确定湿地边界的情况 下, 由于湿地是位于水陆交错带的一个自然综合体, 只要抓住了湿地隐域性的本质, 确定了水体 系统与陆地系统的边界也就确定湿地系统的边界。通过对湿地边界各种指标的合理性和可重复 性分析, 提出地带性土壤诊断层尖灭点作为湿地边界指标, 分析了其科学性和可行性, 并提出了 湿地边界确定的方法。     

Potential use of mangroves as constructed wetland for municipal sewage treatment in Futian, Shenzhen, China

A pilot-scale mangrove wetland was constructed in Futian, Shenzhen for municipal sewage treatment. Three identical belts (length: 33m, width: 3m, depth: 0.5m) were filled with stone (bottom), gravel and mangrove sand (surface). Seedlings of two native mangrove species (Kandelia candel, Aegiceras corniculatum) and one exotic species (Sonneratia caseolaris) were transplanted to the belts with one species for each belt. The hydraulic loading was 5m(3)d(-1) and hydraulic retention time 3d. High levels of removal of COD, BOD(5), TN, TP and NH(3)-N were obtained. The treatment efficiency of S. caseolaris and A. corniculatum was higher than that of K. candel. Faster plant growth was obtained for S. caseolaris. The substrate in the S. caseolaris belt also showed higher enzyme activities including dehydrogenase, cellulase, phosphatase, urease and beta-glucosidase. The removal rates of organic matter and nutrients were positively correlated with plant growth. The results indicated that mangroves could be used in a constructed wetland for municipal sewage treatment, providing post-treatment to remove coliforms was also included.