Sediment and fluvial particulate carbon flux from an eroding peatland catchment     

Changjia Li  Joseph Holden  Richard Grayson 《地球表面变化过程与地形》2019,44(11):2186-2201

Erosion and the associated loss of carbon is a major environmental concern in many peatlands and remains difficult to accurately quantify beyond the plot scale. Erosion was measured in an upland blanket peatland catchment (0.017 km²) in northern England using structure-from-motion (SfM) photogrammetry, sediment traps and stream sediment sampling at different spatial scales. A net median topographic change of –27 mm yr^–1 was recorded by SfM over the 12-month monitoring period for the entire surveyed area (598 m²). Within the entire surveyed area there were six nested catchments where both SfM and sediment traps were used to measure erosion. Substantial amounts of peat were captured in sediment traps during summer storm events after two months of dry weather where desiccation of the peat surface occurred. The magnitude of topographic change for the six nested catchments determined by SfM (mean value: 5.3 mm, standard deviation: 5.2 mm) was very different to the areal average derived from sediment traps (mean value: –0.3 mm, standard deviation: 0.1 mm). Thus, direct interpolation of peat erosion from local net topographic change into sediment yield at the catchment outlet appears problematic. Peat loss measured at the hillslope scale was not representative of that at the catchment scale. Stream sediment sampling at the outlet of the research catchment (0.017 km²) suggested that the yields of suspended sediment and particulate organic carbon were 926.3 t km^–2 yr^–1 and 340.9 t km^–2 yr^–1, respectively, with highest losses occurring during the autumn. Both freeze–thaw during winter and desiccation during long periods of dry weather in spring and summer were identified as important peat weathering processes during the study. Such weathering was a key enabler of subsequent fluvial peat loss from the catchment. © 2019 John Wiley & Sons, Ltd.  相似文献   

流域尺度土地利用调蓄视角的雨洪管理探析     

苏伟忠  汝静静  杨桂山 《地理学报》2019,74(5):948-961

发达国家雨洪管理焦点历经管网设计、不透水面阈值控制、低影响开发及土地利用管理等过程,呈现“多尺度多视角衔接”趋势。本文聚焦太湖流域土地利用调蓄功能变化机制及管理应用,揭示了1985-2015年来建设占用耕地是调蓄功能降低的主要原因;发现基于小流域的调蓄功能变化与建设用地强度整体低关联,但局部高相关,高相关的地区位于大城市或某些乡镇周边的建设增长热区,而这些热区的建设用地与调蓄空间规模较大且接触机会更多,是开发之前调蓄空间保护、开发控制以及开发之后综合管理等3个土地利用调蓄目标因子协调不当的结果;最后提出流域尺度土地利用调蓄视角的雨洪管理“345”模式,即以3个目标因子和5类控制要素为基础,实施土地利用调蓄创建、防御、拓展与保护等4类差别化战略模式,从更大尺度认识老城区和新区的雨洪关联,拓展海绵城市建设的本土认知和视野。  相似文献   

黑龙江省兴凯湖自然保护区生态系统固碳服务功能评价     

肖红叶  戴慧敏  杨泽  刘国栋  高铁  杨佳佳  张一鹤 《地质与资源》2020,29(6):570-573

湿地是自然界中重要的“碳汇”，其碳储量变化对全球气候变化和温室效应有重要的影响.选择地理位置独特的黑龙江兴凯湖自然保护区作为研究区，根据保护区内不同土壤类型采集表层（0～20 cm）土壤样品，利用遥感解译的保护区土地利用图、土壤储碳量和植物固碳量计算公式，核算兴凯湖自然保护区生态系统固碳服务总量，同时借鉴瑞典碳税法和中国造林成本法，估算兴凯湖保护区固碳服务功能价值为4.9亿元.结果显示，兴凯湖自然保护区湿地固碳服务功能高于全国平均水平，且高于同纬度同属东北平原的莫莫格湿地，为保护区今后的保护管理策略提供了有效的参考依据.  相似文献   

Understanding coastal wetland hydrology with a new regional‐scale,process‐based hydrological model          下载免费PDF全文

Yu Zhang  Wenhong Li  Ge Sun  Guofang Miao  Asko Noormets  Ryan Emanuel  John S. King 《水文研究》2018,32(20):3158-3173

Coastal wetlands represent an ecotone between ocean and terrestrial ecosystems, providing important services, including flood mitigation, fresh water supply, erosion control, carbon sequestration, and wildlife habitat. The environmental setting of a wetland and the hydrological connectivity between a wetland and adjacent terrestrial and aquatic systems together determine wetland hydrology. Yet little is known about regional‐scale hydrological interactions among uplands, coastal wetlands, and coastal processes, such as tides, sea level rise, and saltwater intrusion, which together control the dynamics of wetland hydrology. This study presents a new regional‐scale, physically based, distributed wetland hydrological model, PIHM‐Wetland, which integrates the surface and subsurface hydrology with coastal processes and accounts for the influence of wetland inundation on energy budgets and evapotranspiration (ET). The model was validated using in situ hydro‐meteorological measurements and Moderate Resolution Imaging Spectroradiometer (MODIS) ET data for a forested and herbaceous wetland in North Carolina, USA, which confirmed that the model accurately represents the major wetland hydrological behaviours. Modelling results indicate that topographic gradient is a primary control of groundwater flow direction in adjacent uplands. However, seasonal climate patterns become the dominant control of groundwater flow at lower coastal plain and land–ocean interface. We found that coastal processes largely influence groundwater table (GWT) dynamics in the coastal zone, 300 to 800 m from the coastline in our study area. Among all the coastal processes, tides are the dominant control on GWT variation. Because of inundation, forested and herbaceous wetlands absorb an additional 6% and 10%, respectively, of shortwave radiation annually, resulting in a significant increase in ET. Inundation alters ET partitioning through canopy evaporation, transpiration, and soil evaporation, the effect of which is stronger in cool seasons than in warm seasons. The PIHM‐Wetland model provides a new tool that improves the understanding of wetland hydrological processes on a regional scale. Insights from this modelling study provide benchmarks for future research on the effects of sea level rise and climate change on coastal wetland functions and services.  相似文献   

Dissolved organic matter variations in coastal plain wetland watersheds: The integrated role of hydrological connectivity,land use,and seasonality          下载免费PDF全文

Jacob D. Hosen  Alec W. Armstrong  Margaret A. Palmer 《水文研究》2018,32(11):1664-1681

Dissolved organic matter (DOM) is integral to fluvial biogeochemical functions, and wetlands are broadly recognized as substantial sources of aromatic DOM to fluvial networks. Yet how land use change alters biogeochemical connectivity of upland wetlands to streams remains unclear. We studied depressional geographically isolated wetlands on the Delmarva Peninsula (USA) that are seasonally connected to downstream perennial waters via temporary channels. Composition and quantity of DOM from 4 forested, 4 agricultural, and 4 restored wetlands were assessed. Twenty perennial streams with watersheds containing wetlands were also sampled for DOM during times when surface connections were present versus absent. Perennial watersheds had varying amounts of forested wetland (0.4–82%) and agricultural (1–89%) cover. DOM was analysed with ultraviolet–visible spectroscopy, fluorescence spectroscopy, dissolved organic carbon (DOC) concentration, and bioassays. Forested wetlands exported more DOM that was more aromatic‐rich compared with agricultural and restored wetlands. DOM from the latter two could not be distinguished suggesting limited recovery of restored wetlands; DOM from both was more protein‐like than forested wetland DOM. Perennial streams with the highest wetland watershed cover had the highest DOC levels during all seasons; however, in fall and winter when temporary streams connect forested wetlands to perennial channels, perennial DOC concentrations peaked, and composition was linked to forested wetlands. In summer, when temporary stream connections were dry, perennial DOC concentrations were the lowest and protein‐like DOM levels the highest. Overall, DOC levels in perennial streams were linked to total wetland land cover, but the timing of peak fluxes of DOM was driven by wetland connectivity to perennial streams. Bioassays showed that DOM linked to wetlands was less available for microbial use than protein‐like DOM linked to agricultural land use. Together, this evidence indicates that geographically isolated wetlands have a significant impact on downstream water quality and ecosystem function mediated by temporary stream surface connections.  相似文献   

In situ measurements of wind‐driven salt fluxes through constructed channels in a coastal wetland ecosystem          下载免费PDF全文

Alex K. Manda  Enrique Reyes  James M. Pitt 《水文研究》2018,32(5):636-643

A suite of instruments was deployed in a coastal wetland ecosystem in the Albemarle estuarine system, North Carolina (USA), to characterize wind‐driven transport of saltwater through a constructed (man‐made) channel. Flow velocity, electrical conductivity, and stage were measured in a representative channel over a 2‐month period from May to July 2014, during which 4 wind tides were observed. Collected data show that thousands of metric tons of salt were advected through the channel into coastal wetlands during each event, which lasted up to 4 days. The results reveal that as much as 36% of advected salts accumulated in the wetlands, suggesting that the cumulative effects of these events on the health of coastal wetlands in the Albemarle system may be substantial due to the abundance of constructed channels and the frequency of wind‐driven tidal events. This study is the first to quantify wind‐driven salt fluxes through constructed channels in coastal wetland settings.  相似文献   

艾比湖原核微生物菌群结构演变与环境因子关系分析          下载免费PDF全文

马雪莉  吕杰  马媛  吕光辉 《盐湖研究》2020,28(4):79-90

用非培养法获得新疆维吾尔自治区艾比湖湖底沉积物原核微生物菌群组成,并与已有盐湖原核微生物菌群数据进行比对,分析湖泊由淡水湖向盐湖演替过程中原核微生物群落结构变化规律。实验获得艾比湖原核微生物16S rRNA基因序列,并从NCBI数据库下载赛里木湖、柴窝堡湖和顿巴斯他乌盐湖3个湖泊的非培养原核微生物16S rRNA基因序列数据。用不同盐湖细菌和古菌16S rRNA序列信息构建系统发育树并与其理化指标进行典型性相关分析。同源比对及聚类结果显示,艾比湖湖底沉积物中细菌包括4个门,拟杆菌门(Bacteroidetes)占克隆文库的64%,变形菌门(Proteobacteria)占9.4%,厚壁菌门(Firmicutes)占3.4%,放线菌门(Actinobacteria)占2.6%,此外含有未分类类群20.6%。古菌含有两个门,广古菌门(Euryarchaeota,98.3%)和盐纳古菌门(Nanohaloarchaeota,1.7%)。不同盐湖系统发育树结果显示,随盐度增加,盐湖细菌从变形菌门向拟杆菌门演替；古菌从奇古菌门和泉古菌门向广古菌门和盐纳古菌门演替。RDA结果显示,Na⁺、Cl-、SO₄2-和矿化度对盐湖原核微生物多样性结构起到决定性的作用,K⁺、Mg²⁺和Ca²⁺对艾比湖菌群结构影响作用最为显著。原核微生物群落会随着湖水盐浓度的增加和盐湖化学成分的不同而发生演替。  相似文献   

国内盐湖卤水硼资源提取专利分析          下载免费PDF全文

李玉婷  李禾禾  倪颖  王瑜  葛飞 《盐湖研究》2020,28(3):109-114

基于中国盐湖硼资源开发动态,选择国家知识产权局专利数据,从盐湖卤水硼资源提取相关专利申请时间、地域分布、主要方法等方面进行分析。发现中国专利包含多种盐湖硼资源提取方法,并且逐步走向成熟,其中萃取法已成为研究重点。近期关于多种伴生资源综合开发的专利越来越受到关注。对国内盐湖硼资源提取技术后续开发和产业发展提出了建议。  相似文献   

湿地土壤和沉积物异化铁还原过程研究进展     

朱晓艳  袁宇翔  宋长春  姜明 《湿地科学》2020,18(1):122-128

异化铁还原是湿地土壤和沉积物中重要的生物地球化学过程,也是有机质矿化的主要途径之一。湿地干湿交替等过程会使土壤的氧化还原状态发生改变,影响铁元素及与其相关的元素的迁移和转化。总结了湿地土壤和沉积物中异化铁还原过程及其与碳、磷、硫等元素在生物地球化学循环关键过程中的相互作用,阐述了湿地土壤和沉积物中异化铁还原过程对微量金属元素迁移和转化的影响,分析了影响湿地土壤和沉积物异化铁还原过程的主要环境因子。未来相关研究应集中于湿地土壤和沉积物中异化铁还原微生物分析和纯化、不同有机质形式对异化铁还原过程的影响以及异化铁还原对土壤有机质矿化的贡献。  相似文献   

A note on the lake level variations of Nam Co,south-central Tibetan Plateau from 2005 to 2019     

ShiQiao Zhou 《寒旱区科学》2020,12(6):430-435

Tibetan lake levels are sensitive to global change, and their variations have a large impact on the environment, local agriculture and animal husbandry practices. While many remote sensing data of Tibetan lake level changes have been reported, few are from in-situ measurements. This note presents the first in-situ lake level time series of the central Tibetan Plateau. Since 2005, daily lake level observations have been performed at Lake Nam Co, one of the largest on the Tibetan Plateau. The interannual lake level variations show an overall increasing trend from 2006 to 2014, a rapid decrease from 2014 to 2017, and a surge from 2017 to 2018. The annual average lake level of the hydrological year (May-April) rose 66 cm from 2006 to 2014, dropped 59 cm from 2014 to 2017, and increased 20 cm from 2017 to 2018, resulting in a net rise of 27 cm or an average rate of about 2 cm per year. Compared to the annual average lake level based on the calendar year, it is better to use the annual average lake level based on the hydrological year to determine the interannual lake level changes. As the lake level was stable in May, it is appropriate to compare May lake levels when examining interannual lake level changes with fewer data. Overall, remote sensing results agree well with the in-situ lake level observations; however, some significant deviations exist. In the comparable 2006-2009 period, the calendar-year average lake level observed in-situ rose by 10-11 cm per year, which is lower than the ICESat result of 18 cm per year.  相似文献