亚铁对水平潜流人工湿地反硝化作用的影响

亚铁离子可以作为电子供体参与反硝化作用,某些微生物可以通过氧化亚铁离子还原硝酸盐,从而去除污水中的硝态氮.本研究通过在潜流人工湿地中添加Fe2+,分析不同初始Fe2+浓度对反硝化过程的强化效果及不同C/N对Fe2+参与反硝化作用的影响.结果表明,Fe2+的添加可以显著提高人工湿地反硝化能力,进水NO-3-N为30 mg·L-1、C/N为2、水力停留时间为1 d,添加45 mg·L-1Fe2+的人工湿地中硝氮去除率可以提高24%;硝氮去除率随初始Fe2+浓度的增加而增加.C/N与初始Fe2+浓度对反硝化作用都具有显著影响且两者具有交互作用,碳源的存在可以促进Fe2+参与的反硝化作用.     

昆明市湿地公园地表灰尘重金属污染特征及健康风险评价

城市湿地公园是人们休闲娱乐的重要场所,但其地表灰尘的人群暴露健康风险却鲜有报道。该研究收集昆明市3个最受欢迎的湿地公园景区地表灰尘样品,利用等离子发射光谱仪(ICP-OES)测定灰尘中Pb、Cd、Hg、As、Zn、Cr、Cu、Ni、Co、Mn含量,使用地累积指数法(I_geo)、污染负荷指数法(PLI)和潜在生态风险指数法(RI)探讨湿地公园灰尘重金属污染特征,借助美国环保署健康风险评价模型,开展成人和儿童的重金属健康风险评价。结果表明：灰尘中10种重金属平均含量均超昆明市土壤背景值,其中Cd、Hg和Zn平均含量超背景值6倍,Cr、Ni、Co的I_geo<1。污染负荷指数法结果显示Hg、Cd、Zn中度污染,Pb、Cu和As则具有中等以上生态风险。人体健康风险评价结果显示,经口摄入为重金属主要暴露途径,其次是皮肤直接接触和呼吸吸入。Ni、As、Cd、Co和Cr的致癌风险值均小于10^-6,但若长期处于此种环境,可能会存在潜在的致癌风险。对于非致癌元素而言,Pb、Zn、Cu、Mn非致癌健康风险值都远小于1,即风险可以忽略。     

人工湿地废水处理机理

对人工湿地的构造、作用机理进行了较详尽的说明,湿地中物理、化学及生物协同作用以及湿地植物输氧造成的湿地基质中好氧、缺氧和厌氧状态的交替出现是保证其对氮磷及有机物具有较强处理效率的原因。研究表明：对进水浓度较低的城市污水,湿地的ＢＯＤ５和ＣＯＤ去除率大于８０％,出水ＢＯＤ２为１０ｍｇ／Ｌ左右。总氮及总磷去除率可大６０％和９０％,较常规二级处理方式具有一定的优越性。     

ZnCo-LDHs改性人工湿地沸石基质对城市污水的净化效果

选取常用的垂直流人工湿地沸石基质,采用金属离子物质的量比(Zn~(2+)∶Co~(3+))为2∶1在碱性环境下共沉淀生成ZnCo-LDHs,并覆膜于沸石基质表面,分析了改性前后基质的物化特性;构建模拟垂直流人工湿地基质试验柱,对改性前后2种沸石基质对城市污水的净化效果进行了研究。结果表明:Zn Co-LDHs覆膜改性沸石基质的方法是可行的;ZnCo-LDHs覆膜于基质表面,改变了原始沸石基质的物理化学特性,促进了基质对污染物的物理拦截和物化吸附作用;ZnCo-LDHs改性基质对城市污水中CODCr、氨氮、TP的净化效果均有所提高,其平均去除率分别达到了76%、63%和88%。     

山地小微湿地生态修复探讨 ——以梁平区猎神村梯塘小微湿地为例

小微湿地是乡村景观的组成部分,是乡村重要的水土基础设施.湿地的功能已经得到广泛认同,但过去多关注大面积成片分布的沼泽、湖泊、滨海湿地及大型河流湿地等,而对于那些数量众多、分散分布的小型和微型湿地却缺少关注.2018年10月,《湿地公约》第十三届缔约方大会通过了中国政府提交的《小微湿地保护与管理决议草案》,小微湿地的保护...     

碎石床湿地去除城镇污水厂出水中磷的研究

为解决城镇污水二级生物处理厂脱磷不达标的问题,设计了潜流碎石床湿地,通过其填料的吸附、沉淀和植物摄取作用,对二级生化处理后的城镇污水进行脱磷试验。结果表明碎石床湿地有较高的脱磷效果,当进水TP为1.74mg/L时,出水为0.25mg/L,去除率为85.63%,同时对BOD5、COD、SS、NH3-N等也有一定去除作用。出水不仅能满足《污水综合排放标准》(GB8978-96)一级,而且满足《城市污水再生利用景观环境用水水质标准》(GB/T18921-2002),污水可以回用。潜流碎石床湿地深度脱磷技术运行费用低、管理方便、环境景观好、有推广应用价值。     

Modelling Wetland Bird Response to Water Level Changes in the Lake Ontario – St. Lawrence River Hydrosystem

Lake Ontario and St. Lawrence River (LOSL) wetland bird abundance and diversity are greatly influenced by lake and river hydrology. Our study used an interdisciplinary ecosystem approach, blending avian and plant ecology, ecohydraulic, statistical ecology and modelling to evaluate potential impacts of water level fluctuations on indicator species representative of the wetland breeding bird assemblages in the entire LOSL freshwater system. Multi-year (2000–2003) bird surveys captured bird distribution and density in wetland habitats under varying degrees of water inandation, depth and fluctuation. Analyses revealed strong associations between estimated breeding pair densities and plant communities, water depth, and degree of water level fluctuation during the breeding season for a suite of wetland bird species using marsh, wet meadow, shrub swamp and treed swamp habitats. These quantitative associations were used to develop wetland bird performance indicators for use in a LOSL water regulation review study. Several bird species also nest at or near the water surface and are thus vulnerable to nest flooding or stranding. Changes to the seasonal hydrology of Lake Ontario and St. Lawrence River that result in an increased frequency or magnitude of these nest failure events may have a significant impact on regional population sustainability. Long term nest record databases were analyzed to create nesting flooding and stranding probability equations based on water level increases and decreases during the breeding season. These species-specific nesting relationships were incorporated into a reproduction index.Many breeding bird species were strongly associated with specific wetland plant communities. Predicted habitat suitability, as measured by estimated breeding pair density, can also change significantly within a specific wetland plant community based solely on changes in water depth during the breeding season. Three indicator species, Black Tern, Least Bittern and Virginia Rail were selected as key environmental performance indicators for alternate regulation plan comparisons.Water regulation criteria should be such that the long term diversity and abundance of wetland plant communities and frequency of spring flooding in marsh habitats during breeding are not reduced. Magnitude and frequency of water level change during the nesting season (May–July) can also adversely impact reproductive success of many wetland bird species. As such, regulation criteria that increase the seasonal magnitude and frequency of water level change may be detrimental to the long term viability of certain regional breeding bird populations.     

The Ecotoxicological Recovery of Ely Creek and Tributaries (Lee County, Va) After Remediation of Acid Mine Drainage

The Ely Creek watershed (Lee County, VA) was determined in 1995 to be the most negatively affected by acid mine drainage (AMD) within the Virginia coalfield. This determination led the US Army Corps of Engineers to design and build passive wetland remediation systems at two major AMD seeps affecting Ely Creek. This study was undertaken to determine if ecological recovery had occurred in Ely Creek. The results indicate that remediation had a positive effect on all monitoring sites downstream of the remediated AMD seeps. At the site most impacted by AMD, mean pH was 2.93 prior to remediation and improved to 7.14 in 2004. Benthic macroinvertebrate surveys revealed that one AMD influenced site had increased taxa richness from zero taxa in 1997 to 24 in 2004. While in situ testing of Asian clams resulted in zero survival at five of seven AMD influenced sites prior to remediation, some clams survived at all sites after. Clam survival was found to be significantly less than upstream references at only two sites, both downstream of un-mitigated AMD seeps in 2004. An ecotoxicological rating (ETR) system that combined ten biotic and abiotic parameters was developed as an indicator of the ecological status for each study site. A comparison of ETRs from before and after remediation demonstrated that all sites downstream of the remediation had experienced some level of recovery. Although the remediation has improved the ecological health of Ely Creek, un-mitigated AMD discharges are still negatively impacting the watershed.     

Modeling Wetland Plant Community Response to Assess Water-Level Regulation Scenarios in the Lake Ontario – St. Lawrence River Basin

The International Joint Commission has recently completed a five-year study (2000–2005) to review the operation of structures controlling the flows and levels of the Lake Ontario – St. Lawrence River system. In addition to addressing the multitude of stakeholder interests, the regulation plan review also considers environmental sustainability and integrity of wetlands and various ecosystem components. The present paper outlines the general approach, scientific methodology and applied management considerations of studies quantifying the relationships between hydrology and wetland plant assemblages (% occurrence, surface area) in Lake Ontario and the Upper and Lower St. Lawrence River. Although similar study designs were used across the study region, different methodologies were required that were specifically adapted to suit the important regional differences between the lake and river systems, range in water-level variations, and confounding factors (geomorphic types, exposure, sediment characteristics, downstream gradient of water quality, origin of water masses in the Lower River). Performance indicators (metrics), such as total area of wetland in meadow marsh vegetation type, that link wetland response to water levels will be used to assess the effects of different regulation plans under current and future (climate change) water-supply scenarios.The Canadian Crown reserves the right to retain a non-exclusive, royalty free licence in and to any copyright.     

Effects of anthropogenic landscapes on population maintenance of waterbirds

Anthropogenic impacts have reduced natural areas but increased the area of anthropogenic landscapes. There is debate about whether anthropogenic landscapes (e.g., farmlands, orchards, and fish ponds) provide alternatives to natural habitat and under what circumstances. We considered whether anthropogenic landscapes can mitigate population declines for waterbirds. We collected data on population trends and biological traits of 1203 populations of 579 species across the planet. Using Bayesian generalized linear mixed models, we tested whether the ability of a species to use an anthropogenic landscape can predict population trends of waterbird globally and of species of conservation concern. Anthropogenic landscapes benefited population maintenance of common but not less-common species. Conversely, the use of anthropogenic landscapes was associated with population declines for threatened species. Our findings delineate some limitations to the ability of anthropogenic landscapes to mitigate population declines, suggesting that the maintenance of global waterbird populations depends on protecting remaining natural areas and improving the habitat quality in anthropogenic landscapes. Article impact statement: Protecting natural areas and improving the quality of anthropogenic landscapes as habitat are both needed to achieve effective conservation.