Sources of variability in springwater chemistry in Fool Creek,a high-elevation catchment of the Rocky Mountains,Colorado, USA     

Charles C. Rhoades  Timothy S. Fegel  Timothy P. Covino  Kathleen A. Dwire  Kelly Elder 《水文研究》2021,35(3):e14089

Springs are the point of origin for most headwater streams and are important regulators of their chemical composition. We analysed solute concentrations of water emerging from 57 springs within the 3 km² Fool Creek catchment at the Fraser Experimental Forest and considered sources of spatial variation among them and their influence on the chemical composition of downstream water. On average, calcium and acid neutralizing capacity (bicarbonate-ANC) comprised 50 and 90% of the cation and anion charge respectively, in both spring and stream water. Variation in inorganic chemical composition among springs reflected distinct groundwater sources and catchment geology. Springs emerging through glacial deposits in the upper portion of the catchment were the most dilute and similar to snowmelt, whereas lower elevation springs were more concentrated in cations and ANC. Water emerging from a handful of springs in a geologically faulted portion of the catchment were more concentrated than all others and had a predominant effect on downstream ion concentrations. Chemical similarity indicated that these springs were linked along surface and subsurface flowpaths. This survey shows that springwater chemistry is influenced at nested spatial scales including broad geologic conditions, elevational and spatial attributes and isolated local features. Our results highlight the role of overlapping factors on solute export from headwater catchments.  相似文献   

二价铁氧化对铁锰循环功能微生物活性的影响及机制          下载免费PDF全文

屈婧祎  童曼  袁松虎 《地球科学》2021,46(2):632-641

地质微生物是沉积环境中铁、锰氧化还原循环的主要驱动因子,铁锰共存环境中二价铁氧化对不同铁、锰循环功能微生物活性的影响差异和机制尚不清楚.以铁还原菌Shewanella oneidensis MR-1、铁氧化菌Pseudogulbenkiania sp.strain 2002、锰氧化菌Pseudomonas putida MnB1和Leptothrix discophora SS-1作为代表性的铁、锰循环功能微生物,利用平板计数、荧光显微镜等手段探究了Fe(II)氧化对功能微生物活性的影响差异及机制.结果表明0.05 mM Fe2+氧化60 min可使MR-1和MnB1的活菌数量降低4~5个数量级,SS-1及S.2002无显著失活.Fe(II)氧化产生的吸附态。OH和胞内。OH是细菌失活的主要原因,胞外H₂O₂、胞外游离态。OH和三价铁氧化物是细菌失活的次要原因,SS-1及S.2002产生了氧化应激反应,成功抵御了活性氧化物种.   相似文献   

The Bear Brook Watershed in Maine: Multi-decadal whole-watershed experimental acidification     

Kaizad F. Patel  Ivan J. Fernandez  Sarah J. Nelson  Stephen A. Norton  Cheryl J. Spencer 《水文研究》2021,35(5):e14147

The Bear Brook Watershed in Maine (BBWM) is a long-term research site established to study the response of forest ecosystem function to environmental disturbances of chronic acidic deposition and ecosystem nitrogen enrichment. Starting in 1989, the West Bear (treated) watershed received bimonthly applications of ammonium sulfate [(NH₄)₂SO₄] fertilizer from above the canopy, whereas East Bear (reference) received ambient deposition. The treatments were stopped in 2016, marking the beginning of the recovery phase. Research at the site has focused on soils, streams, and vegetation. Here, we describe data collected over three decades at the BBWM—input and stream output nutrient fluxes, quantitative soil pits and soil chemistry, and soil temperature and moisture.  相似文献   

Silica biogeochemical cycle in temperate ecosystems of the Pampean Plain,Argentina     

《Journal of South American Earth Sciences》2015

Silicophytoliths were produced in the plant communities of the Pampean Plain during the Quaternary. The biogeochemistry of silicon is scarcely known in continental environments of Argentina. The aim of this work is to present a synthesis of: the plant production and the presence of silicophytoliths in soils with grasses, and its relationship with silica content in soil solution, soil matrix and groundwaters in temperate ecosystems of the Pampean Plain, Argentina. We quantified the content of silicophytoliths in representative grasses and soils of the area. Mineralochemical determinations of the soils' matrix were made. The concentration of silica was determined in soil solution and groundwaters. The silicophytoliths assemblages in plants let to differenciate subfamilies within Poaceae. In soils, silicophytoliths represent 40–5% of the total components, conforming a stock of 59–72 × 10³ kg/ha in A horizons. The concentration of SiO₂ in soil solution increases with depth (453–1243 μmol/L) in relation with plant communities, their nutritional requirements and root development. The average concentration of silica in groundwaters is 840 umol/L. In the studied soils, inorganic minerals and volcanic shards show no features of weathering. About 10–40% of silicophytoliths were taxonomically unidentified because of their weathering degrees. The matrix of the aggregates is made up by microaggregates composed of carbon and silicon. The weathering of silicophytoliths is a process that contributes to the formation of amorphous silica-rich matrix of the aggregates. So, silicophytoliths could play an important role in the silica cycle being a sink and source of Si in soils and enriching soil solutions and groundwaters.  相似文献   

硫酸盐还原菌及异化铁还原菌对 黄钾铁矾还原作用的对比          下载免费PDF全文

王红梅  刘烁  刘邓 《地球科学》2015,40(2):305-316

选取酸性矿坑水环境中常见的次生含铁硫酸盐矿物———黄钾铁矾[KFe3(SO4)2(OH)6]为研究对象,用硫酸盐还原菌 Desulfovibriovulgaris 和异化铁还原菌Shewanellaputrefaciens CN32对其进行还原实验,探讨作为重金属治理潜在材料的 黄钾铁矾的微生物稳定性.实验采用非增长型培养基,在中性、厌氧、30℃的条件下进行.采用湿化学方法测量水溶液及还原产 生的总Fe2+ ,利用X射线衍射(X-raydiffraction,简称XRD)来分析反应后残余固体物质的矿物组成,用扫描电镜(scanning electronicmicroscopy,简称SEM)观察固体残余物的形貌特征.结果表明,没有微生物的参与,黄钾铁矾的稳定性较好.异化铁 还原菌S.putrefaciens CN32和硫酸还原菌D .vulgaris 在营养极其匮乏的中性厌氧条件下均能还原黄钾铁矾晶格中的 Fe3+ ,显示出黄钾铁矾被微生物还原的可能性.S.putrefaciens CN32还原黄钾铁矾晶格中Fe3+ 的最大还原速率和最终Fe3+ 还原率分别为0.001mmol·L-1·h-1和0.37%.与S.putrefaciens CN32不同,D .vulgaris 对黄钾铁矾的还原能力较强,不 含有电子穿梭体(Anthraquinone-2,6-disulfonate,简称AQDS)的实验体系中Fe3+ 的最大还原速率和最终Fe3+ 还原率分别为 0.017mmol·L-1·h-1和16.80%,而添加了AQDS的实验体系的则分别达到了0.026mmol·L-1·h-1和24.30%,这可能与 黄钾铁矾中含有SO42- 有关.D .vulgaris 优先还原黄钾铁矾晶格中的SO42- 产生的H2S是强还原剂,也可促进Fe3+ 的还原, 微生物以及H2S的双重作用可能是导致D .vulgaris 体系中Fe3+ 还原率较高的原因.XRD分析表明,黄钾铁矾经过S.putrefaciens CN32的作用,物相没有发生变化;而经过D .vulgaris 作用后,黄钾铁矾的特征峰消失,固相残余物中出现了菱铁 矿(FeCO3)、蓝铁矿[Fe3(PO4)2·8H2O]等次生矿物.由于培养基中没有添加任何的磷酸盐,因此蓝铁矿的出现可能是由于培 养基中添加的少量酵母浸膏降解后产生的磷酸根与D .vulgaris 还原黄钾铁矾产生的Fe2+ 相互作用的结果.这些认识对深入 理解地球表层铁的生物地球化学循环具有重要意义,为矿山环境重金属的污染治理提供了实验依据.   相似文献   

A Linked Physical and Biological Framework to Assess Biogeochemical Dynamics in a Shallow Estuarine Ecosystem     

C. P. Buzzelli  R. L. Wetzel  M. B. Meyers 《Estuarine, Coastal and Shelf Science》1999,49(6):829

The littoral zone of Chesapeake Bay contains a mosaic of shallow vegetated and nonvegetated habitats with biotic components that are sensitive to changes in biological and physical driving factors. Static and dynamic modelling frameworks provide an integrative way to study complex hydrodynamic and biogeochemical processes in linked estuarine habitats. In this study we describe a spatial simulation model developed and calibrated relative to a specific littoral zone, estuarine ecosystem. The model consisted of four distinct habitats that contained phytoplankton, sediment microalgae, Zostera marina (eelgrass), and Spartina alterniflora. There was tidal exchange of phytoplankton, particulate and dissolved organic carbon and dissolved inorganic nitrogen between the littoral zone ecosystem and the offshore channel. Physical exchange and biogeochemical transformations within the habitats determined water column concentrations in each habitat. Predicted subtidal water column concentrations and Z. marina and S. alterniflora biomass were within the variability of validation data and the predicted annual rates of net primary production were similar to measured rates. Phytoplankton accounted for 17%, sediment microalgae 46%, the Z. marina community 24% and S. alterniflora 13% of the annual littoral zone primary production. The linked habitat model provided insights into producer, habitat and ecosystem carbon and nitrogen properties that might not have been evident with stand-alone models. Although it was an intra-ecosystem sink for particulate carbon, the seagrass habitat was a DOC source and responsible for over 30% of the littoral zone carbon and nitrogen primary production. The model predicted that the Goodwin Islands littoral zone was a sink of channel derived POC, but a source of DOC to the surrounding estuary. The framework created in this study of estuarine ecosystem dynamics is applicable to many different aquatic systems over a range of spatial and temporal scales.  相似文献   

土著微生物作用下含水层沉积物砷的释放与转化   总被引：4，自引：0，他引：4  

郭华明  唐小惠  杨素珍  沈照理  张玲 《现代地质》2009,23(1):86-93

在原位采集内蒙古河套平原高砷含水层中沉积物和土著微生物的基础上,进行了室内微生物淋滤实验研究。实验过程中,使用了3种水溶液(包括去离子水和2种人工配水)和2种营养条件(包括添加2%葡萄糖和未添加葡萄糖)。结果表明,葡萄糖可强化土著微生物的活性,使得悬浮液pH值明显降低,并增加悬浮液中As质量浓度。配水成分影响悬浮物中As质量浓度。在第9 d之后,添加葡萄糖的样品中存在一定强度的硫酸根还原作用,且这种脱硫酸作用受配水成分的影响较小。研究表明,土著微生物影响下砷的释放和转化过程包括沉积物中As(V)的释放、溶液中As(V)的还原以及沉积物中As(Ⅲ)的释放等。与溶液As(V)相比,As(Ⅲ)更有利于沉积物As的释放。在As释放的过程中,溶液中Fe/Mn含量同时增加,且呈很好的线性相关关系。这意味着土著微生物作用下Fe/Mn氧化物矿物的还原性溶解是导致沉积物As释放的主要原因之一。  相似文献   

Biogeochemistry of Nutrient Elements in the Changjiang （Yangtze River） Estuary     

王保栋  屠建波 《海洋通报(英文版)》2005,7(2):72-79

Introduction The estuarine and coastal waters are nutrient-enriched and the nutrient ratios have been altered as a result of the changed riverine input due to land-use change and anthropogenic nutrient emission over the last century [1, 2]. Estuarine and coastal ecosystems respond to such changes in nutrient budgets by shifting population dynamics of phytoplankton and hence of the rest of the food web, leading to changes in top-down as well as bottom-up control of community structures [3]. Sin…  相似文献   

Effects of catastrophic flooding on stream biogeochemistry in a headwater stream in Shenandoah National Park,USA     

K.S. Reinhardt  T. Furman 《水文研究》2008,22(18):3759-3771

This study examined the stream chemistry changes in Staunton River (a second‐order headwater stream with an average annual discharge 704 m³ ha^?1 yr^?1, Shenandoah National Park, Virginia) resulting from a catastrophic flood in June 1995. This flood, which followed after 800 mm of rain in a 4‐day period, caused large‐scale debris flows and complete scouring of riparian soils down to bedrock in the lower 2 km of the stream, and has been estimated to be a 1000‐year flood. The flood affected stream chemistry on both short‐ and long‐term time scales. The primary short‐term response was elevations in stream concentration of Ca²⁺, Mg²⁺, and K⁺ by 59%, 87%, and 49%, respectively, for 6 months immediately following the flood. The long‐term impact of decreased concentration of all base cations and SiO₂ during summer months (8% average) lasted about 2 years. At the episodic time scale, Ca²⁺, Mg²⁺, and K⁺ flushed from soil sources during pre‐flood storms while Na⁺ and SiO₂ diluted; these trends generally reversed during post‐flood storms for 2 years. Short‐term effects are attributed to the leaching of unconsolidated soil and upturned organic matter that clogged the streambed after the flood. The long‐term and superimposed episodic impacts may have resulted from the loss of riparian soils and vegetation in the flood. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Infaunal burrow ventilation and pore-water transport in muddy sediments     

D.H. Shull  J.M. Benoit  C. Wojcik  J.R. Senning 《Estuarine, Coastal and Shelf Science》2009

The ventilation of burrows by tube-dwelling benthos is understood to be important in determining rates of exchange of solutes between the sediment and overlying water. However, few models have attempted to link the burrow ventilation behavior of tube-dwelling organisms with their geochemical consequences. The classic cylinder model of bioirrigation in muddy sediments (Aller, R.C., 1980. Quantifying solute distributions in the bioturbated zone of marine sediments by defining an average microenvironment. Geochimica et Cosmochimica Acta 44, 1955–1965) links pore-water processes and burrow sizes and distributions in the sediment by assuming that burrows are fully flushed. The equivalence between the cylinder model and the more commonly used one-dimensional non-local exchange model depends upon this assumption. However, this assumption has seldom been tested in the field. We have extended the cylinder model of bioirrigation to include burrow ventilation activities of organisms. Burrow ventilation is modeled as a simple non-local exchange of burrow water with overlying water. Model simulations indicate that burrow ventilation has a large effect on vertical profiles and fluxes of solute tracers. We collected data on burrow geometry in the field by CT-scanning freshly collected sediment cores. At the same study sites, we measured activity profiles of ²²²Rn, a naturally occurring radionuclide tracer of pore-water transport. With model geometry independently constrained, we tested the model by comparing our model-predicted profiles with measured profiles. Our results demonstrate that burrows in the field are not fully flushed. Our estimated burrow ventilation rates compare favorably with previous laboratory measurements. The inclusion of realistic burrow ventilation in this pore-water transport model strongly affects modeled solute profiles and fluxes. We demonstrate how model parameters can be determined from field samples and present a model that more realistically simulates pore-water transport processes in muddy sediments.  相似文献