Microbial effects on geochemical behavior of arsenic in As-contaminated sediments   总被引：4，自引：0，他引：4  

J.M. Park  J.S. Lee  J.-U. Lee  H.T. Chon  M.C. Jung 《Journal of Geochemical Exploration》2006,88(1-3):134

The purpose of this study is to investigate the contamination level and chemical speciation of As in sediments from the Hwachon Au mine area, and to study the effects of indigenous bacteria on geochemical behavior of As in As-contaminated sediments from the mine. Concentrations of heavy metal and metalloids in one composite sample of 9 Hwachon sediments were 24.9 As mg/kg, 16.6 Cd mg/kg, 230 Pb mg/kg and 1080 Zn mg/kg. This indicates that this area was seriously contaminated with As, Cd and Zn. From the result of sequential extraction analysis, most of As (87.9%) existed as a phase of As which coprecipitated with Fe oxyhydroxides. Under aerobic condition, As concentration leached from sediments were 4 times higher in non-sterile than in sterile condition. This enrichment of As leaching could be caused by increase of pH and exudation secreted during microbial metabolism. On the other hand, under anaerobic condition, As concentration has dramatically increased in non-sterile solution with time. This As leaching has begun on 4–5th days of incubation and the highest concentration of 511 As μg/l was recorded on about 11th day. Arsenic leaching under anaerobic condition was caused by microbial enhancement of Fe leaching. Total Fe concentration increased from the 4th day, and this Fe leaching might cause lixiviation of As which had been coprecipitated with Fe oxyhydroxide.  相似文献   

Modeling and Validating Long‐Term Dynamics of Diel Dissolved Oxygen with Particular Reference to pH in a Temperate Shallow Lake (Turkey)     

Nusret Karakaya  Fatih Evrendilek  Kerem Güngör 《洁净——土壤、空气、水》2011,39(11):966-971

Long‐term monitoring of changes in dissolved oxygen (DO) and pH is of great importance to quantifying aquatic ecosystem metabolism, particularly for lakes under the changing global environment. During 173 days, diel DO cycles were measured in situ along with the main driving variables of pH, wind speed (WS), and net solar radiation (Rn) in a temperate shallow lake. Best‐fit multiple non‐linear regression (MNLR) models of diel DO time series were built and validated on a monthly basis, with R² values ranging from 42.4% in September to 95.4% in November for validation. The strong relationship between diel DO and pH (r = 0.6) appeared to be related to the patterns of ecosystem productivity and respiration, and sensitivity of decomposing bacteria to changes in pH. pH‐driven lake metabolism appears to have significant implications for diel and seasonal lake metabolism in a changing global environment.  相似文献   

ROBUST: The ROle of BUffering capacities in STabilising coastal lagoon ecosystems     

Rutger de Wit  Lucas J. Stal  Bente Aa. Lomstein  Rodney A. Herbert  Hans van Gemerden  Pierluigi Viaroli  Victor-Ugo Cecherelli  Francisco Rodríguez-Valera  Marco Bartoli  Gianmarco Giordani  Roberta Azzoni  Bart Schaub  David T. Welsh  Andrew Donnelly  Ana Cifuentes  Josefa Antn  Kai Finster  Lise B. Nielsen  Anne-Grethe Underlien Pedersen  Anne Turi Neubauer  Marina A. Colangelo  Sander K. Heijs 《Continental Shelf Research》2001,21(18-19)

“Buffer capacities” has been defined in ecology as a holistic concept (e.g., Integration of Ecosystem Theories: A Pattern, second ed. Kluwer, Dordrecht, 1997, 388pp), but we show that it can also be worked out in mechanistic studies. Our mechanistic approach highlights that “buffering capacities” can be depleted progressively, and, therefore, we make a distinction between current and potential “buffering capacities”. We have applied this concept to understand the limited “local stability” in seagrass ecosystems and their vulnerability towards structural changes into macro-algal dominated communities. We explored the following processes and studied how they confer buffering capacities to the seagrass ecosystem: (i) net autotrophy is persistent in Zostera noltii meadows where plant assimilation acts as a sink for nutrients, this contrasted with the Ulva system that shifted back and forth between net autotrophy and net heterotrophy; (ii) the Z. noltii ecosystem possesses a certain albeit rather limited capacity to modify the balance between nitrogen fixation and denitrification, i.e., it was found that in situ nitrogen fixation always exceeded denitrification; (iii) the nitrogen demand of organoheterotrophic bacteria in the sediment results in nitrogen retention of N in the sediment and hence a buffer against release of nitrogen compounds from sediments, (iv) habitat diversification in seagrass meadows provides shelter for meiofauna and hence buffering against adverse conditions, (v) sedimentary iron provides a buffer against noxious sulfide (note: bacterial sulfide production is enhanced in anoxic sediment niches by increased organic matter loading). On the other hand, in the coastal system we studied, sedimentary iron appears less important as a redox-coupled buffer system against phosphate loading. This is because most inorganic phosphate is bound to calcium rather than to iron. In addition, our studies have highlighted the importance of plant–microbe interactions in the seagrass meadows.  相似文献   

生态足迹评介及国际研究前沿   总被引：68，自引：1，他引：67  

龙爱华  张志强  苏志勇 《地球科学进展》2004,19(6):971-981

生态足迹评价方法是评估可持续发展的一个全球可比的、可测度的直观且综合的指标,有明显的政策含义,是迄今提出的评估可持续发展的众多指标中最受生态经济学界关注、推崇和广泛应用的一个指标。评介了生态足迹方法模型的优缺点,综述了国际上生态足迹研究的最新进展及研究前沿,指出了国内围绕生态足迹研究应该尽快开展的工作：①生态足迹方法模型的改进及应用研究;②丰富生态足迹方法模型携带的信息量和政策内涵;③社会经济系统新陈代谢以及人类对初级生产力的占用研究;④消费模式与全球资源和环境的压力的关系;⑤物质流核算帐户研究和生态包袱分析研究。  相似文献   

城市建成环境存量的空间计算：进展及展望     

鲍毅  黄舟  郭庆华  刘瑜 《遥感学报》2022,26(10):1909-1919

城市建成环境是人类赖以生存的人造环境,城市建成环境存量是指城市中建筑物和基础设施的材料质量。反演城市建成环境存量的空间分布,是数字城市建设的新方向,它能够帮助我们了解城市发展模式,更加有效管理城市资源和废弃物等,对发展城市循环经济、实现城市的可持续发展有着十分重要的意义。本文详细介绍了城市建成环境存量空间计算的3种方法（自上而下、自下而上和遥感计算方法）的理论基础和发展现状,总结了目前的几中方法都存在着过度依赖统计数据、无法兼顾研究区域大尺度和高空间分辨率等问题。在地理大数据时代,更多的数据源为存量的计算带来了新的研究方向。本文总结了新数据源的优势,并展望了结合地理大数据和机器学习方法的存量计算方法,为城市建成环境存量的空间计算提供了一种新的思路。  相似文献   

Simultaneous Degradation of Trichloroethylene and Toluene by Burkholderia cepacia G4 and the Effect of Biotransformation on Bacterial Density          下载免费PDF全文

Shanawar Hamid  Muhammad Tahir Amin  Abdulrahman Ali Alazba  Umair Manzoor 《洁净——土壤、空气、水》2014,42(7):998-1003

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Nickel effects on growth and antioxidative enzymes activities in desert plant Zygophyllum xanthoxylon （Bunge） Maxim     

Yan Lu  XinRong Li  MingZhu He  ZhengNing Wang  HuiJuan Tan 《寒旱区科学》2010,2(5):0436-0444

One-month old Zygophyllum xanthoxylon seedlings were grown under five different Ni concentrations (0, 50, 150, 450 and 900 mg/kg). Growth parameters, tissues Ni accumulation, soluble protein content, photosynthetic pigment content, lipid peroxidation, antioxidative enzyme activities, and proline content were studied after one month of Ni exposure. The significant reduction in fresh biomass in the shoot and roots was detected at high Ni concentrations (≥450 mg/kg), whereas dry biomass was not significantly affected in both organs by any of the Ni doses tested. The Ni contents in the shoots and roots increased in a dose-dependent manner, and Ni contents in roots were higher than that in shoots at all treatments. The high Ni doses elevated soluble protein contents in leaves and roots. No visible symptoms of chlorosis were observed in leaves of plants grown in presence of Ni. Malondialdehyde (MDA) contents significantly increased in leaves and roots at high Ni treatments (≥450 mg/kg), indicating that Ni induces oxidative stress. Enzyme activities might play a central role in cellular protection against the Ni induced oxidative stress. Proline contents proportionally increased with the elevated Ni concentrations. Zygophyllum xanthoxylon revealed moderate Ni tolerance under tested culture conditions, and could be used as tools for revegetation for erosion control in moderate Ni contaminated sites.  相似文献   

摄食对中国对虾能量代谢影响的初步研究   总被引：2，自引：0，他引：2  

张硕  王芳  董双林 《海洋科学》1998,22(2):49-51

于 1996年 5～ 6月在水温 2 5℃时测定了两种规格中国对虾 ( Penaeus chinensis)摄食沙蚕和配合饲料后的耗养率和氨排泄率。小规格中国对虾摄食配饵的代谢率略高于摄食沙蚕 ,而大规格组中摄食沙蚕的代谢率大于摄食配饵组。小规格中国对虾摄食配饵和沙蚕的代谢能比未摄食组提高了 33.2 2 %和 2 7.4 0 %;大规格中国对虾摄食配饵和沙蚕的代谢能比未摄食组提高了 34 .78%和 4 0 .0 5%。中国对虾摄食后的氨排泄率明显增加 ,表明蛋白质在摄食代谢中具有重要作用。  相似文献   

Proline with or without Hydroxyproline Influences Collagen Concentration and Regulates Prolyl 4-Hydroxylase α(I) Gene Expression in Juvenile Turbot(Scophthalmus maximus L.)     

ZHANG Kaikai  MAI Kangsen  XU Wei  ZHOU Huihui  LIUFU Zhiguo  ZHANG Yanjiao  PENG Mo 《中国海洋大学学报(英文版)》2015,14(3)

This study was conducted to investigate the effect of dietary proline(Pro), and Pro and hydroxyproline(Hyp) in combination on the growth performance, total Hyp and collagen concentrations of tissues, and prolyl 4-hydroxylase α(I)(P4H α(I)) gene expression in juvenile turbot feeding high plant protein diets. A diet containing 50% crude protein and 12% crude lipid was formulated as the basal and control, on which other two protein and lipid contents identical experimental diets were formulated by supplementing the basal with either 0.75% Pro(Pro-0.75) or 0.75% Pro and 0.75% Hyp(Pro+Hyp). Four groups of fish in indoor seawater recirculating systems, 35 individuals each, were fed twice a day to apparent satiation for 10 weeks. The results showed that dietary Pro and Hyp supplementation had no significant effect on growth performance and feed utilization of juvenile turbot(P 0.05). Total Hyp and collagen concentrations in muscle were significantly increased when dietary Pro and Hyp increased(P 0.05), and fish fed diet Pro+Hyp showed significantly higher free Hyp content in plasma than those fed other diets(P 0.05). The expression of P4 H α(I) gene in liver and muscle was significantly up regulated in fish fed diet Pro-0.75 in comparison with control(P 0.05); however the gene was significantly down regulated in fish fed diet Pro+Hyp in muscle in comparison with fish fed diet Pro-0.75(P 0.05). It can be concluded that supplement of crystal L-Pro and L-Hyp to high plant protein diets did not show positive effects on growth performance of juvenile turbot, but enhanced total collagen concentrations in muscle.  相似文献   

Downstream evolution of wastewater treatment plant nutrient signals using high-temporal monitoring     

Sarah H. Ledford  Laura Toran 《水文研究》2020,34(3):852-864

Wastewater treatment plants are major point-sources of nutrients to streams globally, but the impact on receiving streams is not always clear. Previous research has shown mixed responses in receiving streams, with some showing no net retention through in-stream processing for large distances below plants and some showing high rates of processing and retention. This study focuses on Sandy Run, a small, suburban stream in Montgomery County, PA, that receives effluent from two plants, where effluent makes up an estimated 50% of outlet discharge at baseflow. Two sites were monitored in late summer baseflow using high-temporal loggers to evaluate nitrate and phosphate retention with distance below the plants. Effluent quantity was monitored immediately below the effluent outfalls using specific conductivity as a conservative signal of solute fluctuations throughout the day. A site 1 km downstream showed diel nitrate changes, but despite moderate gross primary productivity and ecosystem respiration rates, there was little net retention of nutrients and the diel nitrate signal can be attributed to advection and dispersion of variable upstream effluent. A site 5.4 km below the plant showed a diel nitrate signal as well, but baseflow daily hysteresis plots of nitrate and specific conductivity showed the effluent and nitrate peaks did not coincide. Instead, the effluent input signal was seen overnight, but there was in-stream removal and release processes during the day. Over the distance to this site, the stream was metabolizing some of the high nutrient loads, although gross primary productivity and ecosystem respiration rates were lower. It is important to understand subdaily changes in nutrient processing to fully quantify the impacts of effluent on small streams at different scales. Furthermore, looking at the diel signal without considering conservative transport would overestimate in-stream processing.  相似文献