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1.
So far, the MPN technique has been the method chosen for detecting pathogenic bacteria in waters, since it allows us to use larger volumes. In the evaluation, however, comparatively frequently (10 … 15%) nontypical codes occur. The validity of the Poisson model is confirmed for pure cultures by extensive laboratory experiments with pure cultures and controlled mixed cultures. In mixed cultures, however, a comparatively large number of atypical codes occur, since obviously a single organism is not sufficient for the formation of a growth-cover on the test tube, so that the true number of germs may be considerably underestimated. Obviously, the accompanying flora has an inhibiting effect on the salmonella detection.  相似文献   

2.
Salmonella, mainly S. manhattan and S. agona, were detected in about 40 = of the 133 flowing waters which were investigated in the District of Leipzig from June 1988 to June 1989 Possible causes of the occurrence of salmonella were discussed. Within the framework of statistical evaluations, correlation investigations were carried out on findings of chemical and biological examinations and relations found so far were confirmed. The applicability of the standard TGL 6466/01 “quality demands on irrigation water” is critically checked on the basis of the results of investigation; as derived from the result, the necessity of a revision of this TGL is proved.  相似文献   

3.
Reduction of the Concentration of Bacteria and Coliphages along the Flowing Stretch of a Treated Sewage Channel The efficiency of surface waters to eliminate E. coli, fecal streptococci, Salmonella spp., and coliphages was evaluated in a small river which receives treated wastewater and which is rich in submerged macrophytes. The study took place between April and December, 1994. Total colony count, BOD5, O2 concentration and water temperature were determined in the river as well. As the river does not receive additional water downwards along its 17.2 km course, dilution effects could be ruled out as the cause for the elimination of the microorganisms. The reduction is assumed to happen rather due to sedimentation, grazing, and adsorption to the submerged waterplants. Immediately after discharge of the wastewater, the river water contained about 105 cfu/100 mL E. coli and 104 cfu/100 mL fecal streptococci, about 1000 pfu/100 mL coliphages, and, as a rule, was positive for salmonella in 10 mL. The reduction of E. coli, fecal streptococci, salmonella, clostridia, and coliphages at the end of the course was 1 to 2 orders of magnitude. This reduction took place mainly within the first 4.7 km, a part in which, due to low flowing velocities, suspended solids settle down efficiently. Besides, at the end of this part the submerged waterplants are especially abundant. The reduction of suspended solids correlated positively with that of BOD5, bacteria, and coliphages. The reduction of microorganisms was not sufficient to fulfill the requirements of the European Community guidelines for bathing waters and for surface waters used as drinking water source. The regenerating capacity of surface waters is not sufficient to eliminate pathogens from convenionally treated wastewater. Therefore, tertiary treatment is necessary to keep receiving waters reasonably free from pathogens.  相似文献   

4.
微囊藻(Microcystis)产生大量胞外多糖(EPS),包括包裹在细胞外的胶鞘多糖(CPS)和释放到周围环境中的水溶性多糖(RPS).为探究EPS在蓝藻水华发生中的生理生态学意义,迫切需要了解微囊藻EPS的化学特性.本文从太湖分离群体微囊藻,经过大约18个月实验室培养后,其中一些藻株转变为单细胞形态.选择5株群体藻和4株单细胞藻,比较分析这些藻株EPS的化学特性发现:(1)所有9株藻的EPS均为含有脱氧己糖的酸性杂多糖;(2)所有9株藻的CPS的糖醛酸含量(1.2%~2.1%)均低于RPS的糖醛酸含量(2.4%~6.2%);(3)所有9株藻的EPS均含有乙酰基和硫酸基,其中,每一株藻CPS的乙酰基含量均高于RPS的乙酰基含量,所有群体藻CPS的乙酰基含量(4.1%~6.6%)高于所有单细胞藻CPS的乙酰基含量(2.0%~3.2%).本文进而讨论了EPS化学特性对EPS水溶性和微囊藻群体形成的影响,以及对其生态学作用的影响.在这些化学特性中,乙酰取代基团被认为可能是影响微囊藻EPS生理生态学作用的重要因素.  相似文献   

5.
This paper reports baseline levels of litter (macro, meso and microplastics) in sediments collected from different areas of the Croatian MPA of the Natural Park of Tela??ica bay (Adriatic Sea, GSA n. 17). The distribution of total abundance according to size, for all analysed locations evidences that microplastics are the dominant fraction concerning item's numbers. In all analysed samples no macroplastics were found, while microplastics are 88.71% and mesoplastics are 11.29% of the total.  相似文献   

6.
Ashley A. Webb 《水文研究》2009,23(12):1679-1689
Streamflows were measured in two Pinus radiata plantation catchments and one native eucalypt forest catchment in Canobolas State forest from 1999 to 2007. In 2002/2003, clearfall harvesting of 43·2 and 40·3% of two plantation catchments occurred, respectively. Water yields increased by 54 mm (52%), 71 mm (35%) and 50 mm (19%) in the first three years post‐harvest in treated catchment A and by 103 mm (118%), 157 mm (82%) and 119 mm (48%) in treated catchment B relative to the native forest control catchment. In the fourth post‐harvest water year annual rainfall was only 488 mm, which resulted in negligible run‐off in all catchments, regardless of forest cover. In both plantation catchments, monthly streamflows increased significantly (p = 0·01, p < 0·001) due to a significant increase in baseflows (p < 0·001) after harvesting. Monthly stormflows were not significantly affected by harvesting. Flow duration curve analyses indicated a variable response between the two plantation catchments. Treated catchment A was converted from an ephemeral stream flowing 42% of the time pre‐harvest to a temporary stream flowing 82% of the time post‐harvest. These changes occurred throughout all seasons of the year but were most pronounced during summer and autumn when baseflows were maintained post‐harvest but were not observed under native forest or mature pine plantations. By contrast, flow duration increased in treated catchment B from 12% of the time pre‐harvest to 38% of the time post‐harvest with the greatest changes measured during the winter and spring months when streamflow would normally occur under native forest conditions. These observations have important implications for the development of models of plantation water use to be utilized in water resource planning in Australia. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

7.
杭州西湖底泥磷分级分布   总被引：24，自引：2，他引：22  
徐骏 《湖泊科学》2001,13(3):247-254
采用磷分级分离法对在杭州西湖采集的柱状泥样进行了磷分级提取,结果发现：HCl-rP即钙矿磷占据了西湖底泥总磷含量的30％－70％,其余依次为NaOH-rP(16%-40%)和NH4Cl-rP(0.6%-10%);活性磷由NoOH-rP和NH4Cl-rP构成,占总沉积磷的20％－40％,各磷分级组分和活性磷的垂直分布与总磷基本一致,含量随泥层深度的降低逐级增加,在10－30cm处形成峰值,但表层的蓄积量又出现逐层下降的趋势。  相似文献   

8.
In this study, we investigated the occurence of Toxoplasma gondii and checked the sequencing in 56 samples collected from in the Ordu province, Middle Black Sea, Turkey. The samples were collected from drinking and river water and DNA was extracted from all samples. After DNA isolation, the 18S rRNA target gene and B1 gene of T. gondii were amplified by conventional PCR, nested PCR, and loop‐mediated isothermal amplification (LAMP) assay, respectively. Twenty out of 56 samples (35.7%) were Toxoplasma positive by LAMP. The conventional PCR and nested PCR confirmed that 12 and 16 out of 56 samples (21.42 and 28.57%) were positive for Toxoplasma, respectively. All drinking water samples were negative by all three methods. Thirteen Toxoplasma nested PCR products were successfully sequenced. This study achieved detection and sequencing of Toxoplasma from water supplies in the Middle Black sea area in Turkey.  相似文献   

9.
Beach debris abundance and weight were estimated from surveys on 11 beaches of the Gulf of Oman along the Omani coast. Debris were collected on two occasions from 100 m transects, sorted and categorized by origin and type. Overall contaminations ranged from 0.43 to 6.01 items m(-1) of beach front on different beaches with a mean value of 1.79+/-1.04 gm(-1) (95% C.I). In terms of weight, contamination levels ranged from 7.8 to 75.44 gm(-1) of beach front with a mean contamination of 27.02+/-14.48 gm(-1) (95% C.I). In terms of numbers of items, plastic debris ranked first on all beaches followed by either wood items or other organic materials such as cigarette butts. Industrial debris remained few on all beaches (<10%). Most debris had a local origin and, in terms of numbers, were associated with beach recreational activities whereas fishing debris represented the largest proportion of the debris in terms of weight. There were notable differences between beaches in the relative abundance of recreation-related and fishing-related debris.  相似文献   

10.
3种人工载体净化富营养化水体能力的比较   总被引：5，自引：0，他引：5  
通过野外模拟实验,对比3种不同理化性状人工载体(立体填料、生物绳和尼龙纱网)净化太湖梅梁湾富营养化水体的能力,并探讨影响人工载体水质净化能力的生物与非生物因素.结果表明:(1)所选择的3种人工载体均能显著降低水体的浊度,其中尼龙纱网处理组中水体浊度下降了94.2％,其单位质量载体净化量最高(36.18NTU/g);(2)与对照组相比,各人工载体处理组中,水体中藻类的生长都受到极显著抑制;(3)3种人工载体对水体中TN、TP的去除效果差异极显著,其对TN累积去除率分别为25.55％、10.21％、51.54％,对TP累积去除率分别为38.93％、38.33％、62.98％;(4)载体理化性状、附着藻类与细菌的生物量和活性、挂载量以及载体上溶解态营养盐的释放是影响人工载体水质净化能力的重要因素.综上,尼龙纱网因具备单位质量附着生物的生物量与活性高、自身滞留溶解态营养盐少以及质量轻且价格经济等优势成为净化富营养化水体较为理想的人工载体.  相似文献   

11.
A ground-water quality monitoring study was conducted in Kent and Sussex Counties, Delaware. In the coastal region of Sussex County, 210 wells were sampled 12 times each. In noncoastal Sussex and Kent Counties, 272 wells were sampled once each season over a period of one year. Over 99 percent of the wells were in the water-table aquifer. In coastal Sussex County, 32% of the wells had average nitrate concentrations above the EPA drinking-water standard of 10 mg/1 N. In noncoastal Sussex County and Kent County, 21% and 8% of the wells respectively, had nitrate concentrations above 10 mg/1. The highest nitrate concentrations occurred in areas with intensive broiler production or intensive crop production with excessively-drained soils. Nitrate concentrations in forest areas were <1.5 mg/1. Poultry manure, septic tanks and fertilizers all contributed to the high nitrate concentrations. Poultry manure was one of the major causes of nitrate contamination in four out of the five top prioritized ground-water problem areas. Bacteria contamination was low in all sampling areas. Lead, cadmium and chromium were far below drinking-water standards in all but a few wells.  相似文献   

12.
Schroth MH  Istok JD 《Ground water》2006,44(2):275-283
Push-pull tests (PPTs) have been successfully employed to quantify various microbially mediated processes in the subsurface. Current models for determining first-order rate coefficients (k) from PPTs assume complete and instantaneous mixing of injected test solution in the portion of the aquifer investigated by the test, i.e., the system is treated like a well-mixed reactor. Here we present two alternative models to estimate k that are based on different mixing assumptions, i.e., plug-flow and variably mixed reactor models. Rate coefficients estimated by the models were compared using a sensitivity analysis and numerical simulations of PPTs. Results indicated that all models yielded reasonably accurate k estimates (errors < 13%), while best accuracy (errors < 1%) was obtained using the variably mixed reactor model. The well-mixed reactor model generally overestimated true (simulation input) k values, whereas true k values were consistently underestimated by the plug-flow reactor model. However, estimates of k obtained with the latter models bracketed true k values in all cases. As the variably mixed reactor model is more difficult to apply, we suggest using the well-mixed and plug-flow reactor models to obtain intervals for k estimates that will encompass true k values with high certainty. In an example application, we used all models to reanalyze a published PPT data set to obtain k estimates for nitrate consumption in a petroleum-contaminated aquifer. Similar results were obtained for all three models (relative differences < 10% between k estimates), indicating that all three models are robust tools for estimating k values from PPT experimental data.  相似文献   

13.
The analysis of simultaneous observations of 128 cases of high-latitude magnetic impulse events (MIEs), as well as geomagnetic pulsations in the Pc1–2 band observed in the area of the dayside cusp, was carried out. We investigated magnetograms from the Mirny Observatory, Antarctica. As a result of the examination, three groups of impulses were identified: (1) impulses accompanied by impulsive bursts of intervals of pulsations with rising periods (IPRPs)-type geomagnetic pulsations—16% of all events, (2) impulses accompanied by impulsive bursts of the Pi1B type (bursts of irregular magnetic pulsations)—48% of all events, and (3) impulses which were not accompanied by geomagnetic pulsations within a high-frequency band—36% of all events.It was found that the maximum frequency of occurrence of the impulses accompanied by impulsive bursts of the IPRP and Pi1B types was observed between 1200 and 1300 MLT. The events of the first two groups were observed predominantly when Bz>0. It was shown that the filling frequency of impulsive bursts that accompany the occurrence of impulses depends on the amplitude of the bursts. The maximum frequency of the occurrence of impulses which were not accompanied by impulsive bursts is between 1000 and 1100 MLT. The events of the third group were observed predominantly when Bz<0. In most cases, the occurrence of impulsive bursts coincided with the leading edge of the MIE.It is supposed that the MIE generation is stimulated by intensification of the plasma turbulence level at the dayside magnetopause in consequence of modulation instability development or reconnection processes.  相似文献   

14.
Most acceleration diagrams show high levels of unpredictability, as a result, it is the best to avoid using diagrams of earthquake acceleration spectra, even if the diagrams recorded at the site in question. In order to design earthquake resistant structures, we, instead, suggest constructing a design spectrum using a set of spectra that have common characteristics to the recorded acceleration diagrams at a particular site and smoothing the associated data. In this study, we conducted a time history analysis and determined a design spectrum for the region near the Lali tunnel in Southwestern Iran. We selected 13 specific ground motion records from the rock site to construct the design spectrum. To process the data, we first applied a base-line correction and then calculated the signal-to-noise ratio (RSN) for each record. Next, we calculated the Fourier amplitude spectra of the acceleration pertaining to the signal window (1), and the Fourier amplitude spectra of the associated noise (2). After dividing each spectra by the square root of the selected window interval, they were divided by each other (1 divided by 2), in order to obtain the RSN ratio (filtering was also applied). In addition, all data were normalized to the peak ground acceleration (PGA). Next, the normalized vertical and horizontal responses and mean response spectrum (50%) and the mean plus-one standard deviation (84%) were calculated for all the selected ground motion records at 5% damping. Finally, the mean design spectrum and the mean plus-one standard deviation were plotted for the spectrums. The equation of the mean and the above-mean design spectrum at the Lali tunnel site are also provided, along with our observed conclusions.  相似文献   

15.
Metal loads were determined from water samples collected under different streamflow conditions (baseflow and storm events) in a rural catchment (NW Spain) during 4 years. A study at annual, seasonal and storm‐event scales was carried out. In all analysed scales, the export order was Fe > Al > Mn > Zn > Cu. A high inter‐annual, seasonal and storm‐event scale variability of metal load was observed. The total metal loads in stream were higher during baseflow conditions than during storm events, which only represented 4% of the duration of the study period and 25% of streamflow. During storm events, both Al and Fe loads accounted 45% of the total load of the study period, whereas Mn, Cu and Zn loads represented 42%, 33% and 24%, respectively. This highlights the role of high flows on metal export. Only four big events exported around 30% of load of each metal transported in events. At all time scales, a prevalence of export of particulate metals over dissolved metals was observed, more pronounced for Al, Fe and Mn than for Cu and Zn. The export of metals in the Corbeira catchment is influenced by runoff and, to a lesser extent, by the rainfall amount. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

16.
Polar anthropogenic organic micropollutants are frequently detected in freshwater and discharged on large scale into marine systems. In this work the results of 153 samples collected from the shorelines of the Baltic Sea (Germany), Northern Adriatic Sea (Italy), Aegean Sea and Dardanelles (Greece & Turkey), San Francisco Bay (USA), Pacific Ocean (USA), Mediterranean Sea (Israel), and Balearic Sea (Spain) are presented. The samples were analyzed for various classes of micropollutants such as pharmaceuticals, corrosion inhibitors, biocides, and stimulants. Caffeine, paraxanthine, theobromine, tolyltriazole, 1H-benzotriazole, and atrazine were detected in >50% of all samples. The detection frequencies of carbamazepine, iopamidol, diuron, sulfamethoxazole, paracetamol, theophylline, and atenolol were between 20% and 32%. As caffeine is linked to untreated wastewater, the widespread occurrence of raw sewage in marine environments and thus potentially elevated nutrient concentrations and risk for the presence of wastewater-related pathogens is remarkable.  相似文献   

17.
Due to the potentially accumulative nature of the Fladen Ground, an area of intense oil activity in the North Sea, a survey was carried out in 1989 to map the distribution of contamination in relation to these oil activities. All the sediments collected were screened by ultraviolet fluorescence (UVF) for polycyclic aromatic hydrocarbons (PAHs) and selected samples were analysed for n-alkanes (by GC-FID), PAHs and biomarkers (by GC-MSD). This survey was repeated in 2001, with all the 1989 sites being resampled. All of these sediments were analysed for UVF oil equivalents, PAHs, n-alkanes and biomarkers. The concentrations of these parameters decreased between 1989 and 2001, with average decreases ranging from 43% to 88%. In addition, no significant difference was found, for all the parameters, between near field (<5 km from an oil installation) and far field (>5 km from an oil installation) sites in 2001 indicating that the Fladen Ground is approaching a 'steady state' or background concentration for contamination.  相似文献   

18.
Magellanic penguins migrate from Patagonia reaching northern Argentina, Uruguay, and southern Brazil on their winter migration, in parallel with the seasonal pulse of anchovy spawning. In 2008, Magellanic penguins went further north than usual. Many died and a few swam nearly to the Equator. Twelve groups surveyed 5000 km of coastline encountering 3371 penguins along the coast. Most penguins arrived in northern Brazil (68.4%) without petroleum (2933, 87%). Almost all penguins without petroleum were juveniles (2915, 99%) and 55% were alive when found. Penguins were dehydrated, anemic, hypothermic, and emaciated. Of the penguins with petroleum, 13% arrived in the southern half of Brazil, showing that petroleum pollution remains a problem along the SW Atlantic coast. The mortality occurred in the winter of 2008 when sea surface temperature were unusually cold perhaps reducing the prey for penguins.  相似文献   

19.
In compliance with the New Jersey Private Well Testing Act, 78,546 wells (93,787 samples, including samples from 13,290 wells that were analyzed more than once) were analyzed for total coliform (TC) bacteria by one or more of 39 laboratories over a 10‐year period. Samples containing TC bacteria were further analyzed for the presence of either fecal coliform or E. coli (FC/EC) bacteria. The large population of wells sampled multiple times permitted a systematic study of the effect of repeat sampling on coliform bacteria detection rates. The detection rate increased with the number of times wells were sampled. In bedrock, TC bacteria were detected in 21% of the population of wells analyzed only once, 33% in the population sampled twice, and 43% in the population sampled three times. It was estimated that TC bacteria would be detected in 90% of all wells if each well was analyzed 10 times. For FC/EC bacteria, it was estimated that 21 and 68 samples, respectively, would be required to reach the 50% and 90% population detection rates. In the Coastal Plain (CP), many more samples would be required to achieve the same estimated population detection rates. The population detection rate estimates were also dependent on the type of method used, the pH of the well water, and the geologic formation in which wells were located. A single sample was not sufficient to detect coliform bacteria when present in well water.  相似文献   

20.
岑璐瑶  陈滢  张进  刘敏  吴庆明 《湖泊科学》2019,31(2):365-374
利用种植不同植物的人工湿地对污水厂尾水进行深度处理以达到更严格的排放标准.利用5块尺寸一致的中试规模人工湿地,以潮汐流作为运行方式,研究不同植物对尾水的处理效果.经过一年的实验,结果表明：5块人工湿地出水各指标均能达到提升标准的排放要求.在不同植物的去污效果对比实验中,种植芦苇（Phragmites communis）的人工湿地对化学需氧量（COD）、氨氮和总氮（TN）的平均去除率均为最高,分别为24.01%、68.15%和92.70%;种植风车草（Cyperus alternifolius）的人工湿地对TP的平均去除率最高,为71.68%.在不同季节的去污效果对比实验中,春季芦苇湿地对COD、氨氮和TN的去除效果最好,平均去除率分别为52.51%、76.06%和92.04%,美人蕉（Canna indica）湿地对TP去除效果最好,平均去除率为66.72%;夏季对COD、氨氮、TP和TN处理效果最好的分别是种植丝带草（Phalaris arundinacea）、菖蒲（Acorus calamus）、风车草和芦苇的人工湿地,平均去除率分别为15.83%、78.11%、67.30%和91.73%;秋季对COD、氨氮、TP、TN处理效果最好的分别是种植芦苇、丝带草、风车草、美人蕉的人工湿地,平均去除率分别为12.19%、58.82%、83.16%和94.01%;冬季对COD去除效果最好的是种植丝带草的人工湿地,平均去除率为33.39%,对氨氮、TP处理效果最好的是种植美人蕉的人工湿地,平均去除率分别为76.33%和79.43%,对TN处理效果最好的是种植芦苇的人工湿地,平均去除率为94.97%.在以后的实际工程中,可以考虑用种植不同季节、不同指标对应的最佳去污植物为主,并且搭配种植其他植物的人工湿地进行污水厂尾水的深度处理.  相似文献   

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