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941.
Małgorzata Loga Anna Wierzchołowska-Dziedzic 《Environmental monitoring and assessment》2017,189(12):647
Measurement uncertainties are inherent to assessment of biological indices of water bodies. The effect of these uncertainties on the probability of misclassification of ecological status is the subject of this paper. Four Monte-Carlo (M-C) models were applied to simulate the occurrence of random errors in the measurements of metrics corresponding to four biological elements of surface waters: macrophytes, phytoplankton, phytobenthos, and benthic macroinvertebrates. Long series of error-prone measurement values of these metrics, generated by M-C models, were used to identify cases in which values of any of the four biological indices lay outside of the “true” water body class, i.e., outside the class assigned from the actual physical measurements. Fraction of such cases in the M-C generated series was used to estimate the probability of misclassification. The method is particularly useful for estimating the probability of misclassification of the ecological status of surface water bodies in the case of short sequences of measurements of biological indices. The results of the Monte-Carlo simulations show a relatively high sensitivity of this probability to measurement errors of the river macrophyte index (MIR) and high robustness to measurement errors of the benthic macroinvertebrate index (MMI). The proposed method of using Monte-Carlo models to estimate the probability of misclassification has significant potential for assessing the uncertainty of water body status reported to the EC by the EU member countries according to WFD. The method can be readily applied also in risk assessment of water management decisions before adopting the status dependent corrective actions. 相似文献
942.
943.
采用移动床生物膜反应器(MBBR)处理配制模拟废水,实验结果表明,水力停留时间为6h、悬浮填料填充率为40%时,在不同C/N/P比率条件下,MBBR对COD、NH4+-N和TN去除性能好且稳定,平均去除率分别达到90%、94.8%和62.39%以上,而TP的去除率受C/N/P值影响较大,当C/N/P的比值为100/10/1.8时,平均去除率达到58.03%。一定的溶解氧(DO)质量浓度能保证反应器中COD、NH4-N高效稳定的去除,同时是TN和TP同时去除的重要影响因素,在MBBR中最佳DO值约为3mg/L。由于附着在悬浮填料生物膜内部存在厌氧、缺氧微环境条件,在反应器中存在少量的反硝化聚磷菌。 相似文献
944.
Differences between carbon dioxide levels over suburban and rural sites in Northern Spain 总被引:2,自引:0,他引:2
García MA Sánchez ML Pérez IA 《Environmental science and pollution research international》2012,19(2):432-439
Purpose
A comparison between suburban and rural atmospheric carbon dioxide concentrations in Northern Spain is made. 相似文献945.
SBR中SRT对总细菌群落结构的影响研究 总被引:1,自引:0,他引:1
为了揭示序批式反应器不同污泥停留时间(SRT)下总细菌群落结构的异同及SRT变化对总细菌群落结构的影响,应用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)进行研究。通过克隆测序发现,不同的SRT条件下生物多样性和种群结构会有所差异,既存在各SRT条件下相同的优势菌群(Escherichia coli和Aeromonas sp.),也存在某些SRT下特有的优势菌群(Uncultured Peptostreptococcaceae),SRT为40 d时检测到以降解硫酸盐获得能源的优势微生物。研究还表明,SRT为40 d时多样性指数取得最大值,各SRT条件下微生物的种群相似性差别较大。 相似文献
946.
随着天然气勘探开发速度的加快,鄂尔多斯气田井场废泥浆产生量越来越大,固化处理后将其填埋于有防渗层的泥浆池中是目前该区域最常用的方法,但国内外就气田井场泥浆池防渗层对池内污染物实际阻滞效果的研究报道较少。为研究上述处理方法的实际环境效应,以2010年盆地内正在开发气井井场泥浆池内预固化处理沉淀物的分析结果为参照,选择其中污染程度较为严重的石油类、COD、硫化物和砷、钡、镍、铅、铜4种为重点污染物,选择2005—2009年分别投入使用的5个气田井场废弃泥浆池为考察对象,分析研究了防渗层投运时间对不同污染物阻滞作用的影响。结果表明,投运1年的防渗层可阻留污染物90%以上,投运2年以上的防渗层对污染物的阻滞作用有不同程度下降,投运5年的防渗层对所监测污染物的阻滞作用最好的是钡(40.14%)、最差的为硫化物(10.89%),结合不同时间防渗层破损状况和其对污染物的阻滞效率的变化情况,说明机械刺穿和不均匀降是导致防渗层在研究区域的环境下阻滞功能退化较快的主要原因。 相似文献
947.
KH Kim DX Ho CG Park CJ Ma SK Pandey SC Lee HJ Jeong SH Lee 《Environmental engineering science》2012,29(9):875-889
To investigate the environmental behavior of volatile organic compounds (VOCs) in urban areas, their concentrations were measured at four urban monitoring sites (namely, N, S, E, and W) in Seoul, Korea (February to December 2009). A total of 27 compounds were quantified that consist of four chemical groups: aromatic (AR), halogenated aromatic, halogenated paraffin, and halogenated olefin. Results were evaluated by focusing on these four functional groups just mentioned and their summation term as total VOC (TVOC) along with several individual species (mainly AR species, that is, benzene, toluene, ethylbenzene, and xylene). The highest concentration of chemical groups was found from AR (71.1±42.1?ppbC), while that for individual species confirmed the dominance of toluene (7.48±3.88?ppb). The analysis of spatial distribution indicated that high TVOC levels were recorded at sites N and W, while it was not so significant such as S and E in terms of TVOC budget. Seasonal variation of these VOCs was characterized by the peak values in December to reflect the combined effects of pronounced source activities and meteorological conditions. Analysis of spatial variations in VOC levels between the four urban sites indicated that their distributions are tightly affected by local source processes in each area. 相似文献
948.
In the context of water treatment, the ferrate ([FeO(4)](2-)) ion has long been known for its strong oxidizing power and for producing a coagulant from its reduced form [i.e., Fe(III)]. However, it has not been widely applied in water treatment, because of preparation difficulties and high cost. This article describes a low-cost procedure for producing solid potassium ferrate. In this synthetic procedure, NaClO was used in place of chlorine generation; and 10?M KOH was used in place of saturated KOH in the previous procedures. In addition, this study investigated the reactions of potassium ferrate with tetracycline hydrochloride (TC) at different pH and molar ratios. Results showed that the optimal pH range for TC degradation was pH 9-10, and TC could be mostly removed by Fe(VI) in 60?s. However, results showed >70% of TC degraded and <15% of dissolved organic carbon (DOC) reduction at molar ratio of 1:20. The main degradation pathway of TC is proposed based on the experimental data. 相似文献
949.
Short-chain chlorinated paraffins (SCCPs) in surface soil from a background area in China: occurrence, distribution, and congener profiles 总被引:1,自引:0,他引:1
Xue-Tong Wang Yuan Zhang Yi Miao Ling-Ling Ma Yuan-Cheng Li Yue-Ya Chang Ming-Hong Wu 《Environmental science and pollution research international》2013,20(7):4742-4749
Short-chain chlorinated paraffins (SCCPs) are extremely complex technical mixtures of polychlorinated n-alkanes with carbon chain lengths from C10 to C13 and chlorine content between 49 and 70 %. SCCPs are under consideration for inclusion in the Stockholm Convention on persistent organic pollutants. SCCPs have been used extensively in industrial production, but little is known about the pollution level in soil environment in China. In this study, levels and distribution of SCCPs in soil samples from Chongming Island were analyzed. Concentrations of total SCCPs in soil samples ranged from 0.42 to 420 ng?g?1, with a median of 9.6 ng?g?1. The ubiquitous occurrence of SCCPs in Chongming Island implied that long-range atmospheric transport and soil–air exchange may be the most important pathways for SCCP contamination in the background area. The localized SCCP contamination could be derived from an unidentified source. Hierarchical cluster analysis indicated that C13- and C11-congeners were predominant in most soils and C10- and C12-congeners dominated in the remaining soils. Cl7- and Cl8-congeners were on the average the most dominant chlorine congeners in nearly all soils. Principal component analysis suggested that the separation of even and odd carbon chain congeners occurred during long-range atmospheric transport and aging in soil in the study area. 相似文献
950.
针对城市生活垃圾好氧堆肥的处理工艺,设计一种用于好氧堆肥的滚筒式生物反应器。滚筒式生物反应器的设计主要包括主体结构设计,及反应器主体结构强度模拟分析。应用赫兹接触理论对支承装置中滚圈与托轮之间的接触应力进行计算。同时,结合ANSYS中不分离的接触方式模拟分析支承装置的接触应力,得出支承装置接触应力的分布规律,并将理论计算结果与ANSYS模拟结果进行对比。 相似文献