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1.
Storm events are major transporters of faecal microbial contaminants, but few studies have reported storm loads or concentration dynamics in relation to discharge or other pollutants, notably fine sediment. Episodically, high loads of faecal contamination during storm flows impact downstream uses of water bodies, particularly contact recreation and shellfish harvesting. We examined the storm dynamics of Escherichia coli, turbidity and discharge in the mixed land use Motueka catchment (2047 km2; 60% forest and 19% pasture) to gain insights into E. coli sources and transport. We also explored different approaches for calculating E. coli loads. Discharge and field turbidity were recorded continuously, and E. coli concentrations were sampled during events, over a 13‐month period near the mouth of the Motueka River. E. coli loads were estimated by interpolation, averaging estimators and by using linear regression with smearing correction of the log‐transformed variables: discharge, turbidity, and both turbidity and discharge. The annual E. coli load was dominated (～98%) by export during events. Comparison of monthly monitoring with the intensive storm monitoring campaign suggests that simple stratification of the sampling into storm and baseflow would greatly improve export estimates. E. coli peak concentrations always preceded discharge and turbidity peaks (which had similar timing). Turbidity can be a useful surrogate for faecal microbes in smaller catchments, but in the Motueka turbidity was no better for predicting E. coli concentration than discharge. Runoff from grazed pasture and direct deposition from livestock are probably the ultimate E. coli sources in the Motueka catchment. However, in‐channel stores seem to dominate E. coli dynamics during events and account for the typical feature of bacterial concentrations peaking ahead of discharge and turbidity. This study demonstrates the importance of storm events to faecal microbial loads and shows that E. coli concentration dynamics may contrast with those of turbidity. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

2.
In the present study assessment of physicochemical and bacteriological parameters of Lake Fateh Sagar of Udaipur (Rajasthan), India was done. Water samples were collected during different seasons for analysis of physicochemical parameters such as pH, temperature, total alkalinity, total hardness, dissolved oxygen, biological oxygen demand and chemical oxygen demand. In addition, the bacteriological analysis like total bacterial and coliform count was detected. Incidences of Escherichia coli and their antibiotic resistance pattern were analyzed, which is the major microbiological indicator of faecal contamination. The values of some physicochemical and many of the bacteriological parameters were found above the permissible limits for drinking water recommended by World Health Organization. E. coli isolates were identified by morphological, biochemical and molecular characteristics using E. coli specific 16S rRNA gene based primers namely 16E1, 16E2 and 16E3 and universal primers namely 27F and 1492R by PCR. It was found that most of E. coli strains were strongly resistant to kanamycin, ampicillin, cefixime, polymyxin B, penicillin, vancomycin, rifampicin and streptomycin. The study of water quality is of significant value because the drinking water supply of the city is dependent on this lake and present study indicated that the lake water is polluted with reference to these analyzed parameters.  相似文献   

3.
Summary At Fuglebjerg, County of Soroe, South Zeeland (about 1000 inhabitants) a sewage treatment plant, consisting of three lagoons in series, has been installed in an empty gravel pit. The plant has been in use since May 1952 and has produced a most satisfactory effluent. Two times a year, chemical, bacteriological, and biological examinations have been performed, besides occasional more restricted investigations. The bacteriological examinations have chiefly taken into consideration, the reduction in counts of faecal bacteria, of whichE. coli is diminished considerably,Str. faecalis, and especiallyCl. welchii much less. The special value of the two last mentioned organisms as indicators of the efficiency of purification and the condition in the receiving streams is stressed. As regards the change in microflora in the course of treatment, a variation takes place from polysaprobic micro-communities characterized bybacteria andflagellates via α-mesosaprobic zones (flagellates andblue-green algae) to β-mesosaprobic conditions dominated bydiatoms.  相似文献   

4.
The presence of pathogenic bacteria in water, along with the factors that act upon them, constitutes a field that has been little investigated in natural environments. It is clear, however, that these pathogens do have a significant effect on the quality of drinking water. Selected bacteria such as Salmonella, Campylobacter, Yersinia, and Listeria were searched for in groundwaters of mainly mountainous regions. Waters of one or two brooks in the catchment area of each spring were also analysed. Our results show that Campylo bacter and Listeria are frequent in all of these waters, even when land use in the catchment area is extensive (mountain pastures). Salmonella, on the other hand, was never found. Factors influencing the presence of Campylobacter, Yersinia, and Listeria were tested using Spearman rank correlations. The results suggest that the presence in water of some species of these bacteria (C. jejuni, L. monocytogenes 4b, and L. ivanovii) is related to a contaminant input, i.e. to the presence of cattle in the catchment area. For other species (C. coli, L. monocytogenes 1/2a, and Yersinia enterocolitica), however, one is forced to admit that no such connection between the presence of these species and that of an identified, potential contaminant input exists. We are therefore obliged to conclude either that these bacteria multiply in a natural way in the environment, or that they are able to survive in it for a long time. Finally, the present study shows that pathogenic bacteria are not always accompanied by indicators of faecal contamination (Escherichia coli, entero cocci); for this reason, they could potentially pose a risk to public health.  相似文献   

5.
Bathing water quality is an important public health issue, mainly because of fecal contamination. In 2006, the European Commission (EC) adopted a new directive with respect to recreational bathing waters that calls for stricter standards and reduces the number of laboratory tests done in routine beach monitoring from nineteen to two bacterial indicators, namely, Escherichia coli and intestinal enterococci, replacing policies of the EC Bathing Water Directive that have existed since 1976. Our practice in Portugal is in line with this international development, and this study demonstrates the equivalency of the new bacteriological parameters with the old. The water quality of 25 coastal beaches was surveyed using both new and old microbiological indicators of fecal contamination. Statistical analysis demonstrated equivalency of the results obtained for fecal coliforms with Escherichia coli and for fecal streptococci with intestinal enterococci.  相似文献   

6.
The physico‐chemical characteristics and microbial composition of the final effluents of two municipal wastewater treatment plants in South Africa were assessed between July and September 2009. The impact of the treated final effluents on the receiving water bodies was also evaluated. The temperature across all sampling points ranged between 14 and 22°C, while pH varied from 6.9 to 7.6. High levels of turbidity, chemical oxygen demand (COD), ammonia, nitrate, nitrite and orthophosphate (PO4) were observed in many cases. Turbidity of the samples was in the range of 2.2–288.6 NTU. The concentrations (mg/L) of other physico‐chemical parameters are as follows: COD (9.33–289); ammonia (0.000340–45.4); nitrate (0.062–539); nitrite (0.021–22.6); PO4 (5.3–33.2). The microbial quality of the effluents discharged from the plants did not comply with the limits set by the South African guidelines with respect to pathogens such as Salmonella, Shigella, Escherichia coli, total coliform, faecal coliform, enterococci, faecal streptococci, and viral particles for effluents intended for discharge into receiving watersheds. This study revealed an undesirable impact on the physico‐chemical and microbial qualities of the receiving water bodies as a result of the discharge of inadequately treated effluents from the wastewater treatment facilities. This poses a health risk to several rural communities which rely on the receiving water bodies primarily as their sources of domestic water and recreational purposes. There is therefore a need for the intervention of appropriate regulatory agencies in South Africa to ensure compliance of treatment facilities with wastewater effluent quality standards.  相似文献   

7.
In three drinking water sources i. e. river, well and filter water, there were detected 50 taxa of animals: 10 amoebae and 2 ciliates (protozoa), 24 rotifera, 5 cladocerans, and 9 copepods. Chief components of the rotifers population were Brachionus and Keratella, although K. cochlearis is the most common form at all the sites. The presence of Entamoeba histolytica in well water was indicative of faecal contamination which may become a causative agent of amoebiasis in human beings.  相似文献   

8.
Sediment from the sewage sludge dump site area in the New York Bight contains bacteria resistant to antibiotics and heavy metals. The purpose of this study was to determine if antibiotic resistance could be transferred from donor to recipient Escherichia coli strains inoculated into glass vessels containing sediment and seawater obtained near the dump site. Temperature was maintained at 10°C, the mean winter temperature of benthic water at the dump site. Transconjugants (recipients which inherit donor genes for tetracycline resistance) were isolated from the seawater and sediment within one hour after inoculation and were found in all subsequent sediment samples for one month. Donor and recipient E. coli remained viable in the sediment for at least one month. Our results indicate that sewage sludge polluted sediment may serve as an environment conducive to conjugal transfer of antibiotic resistance genes.  相似文献   

9.
We hypothesized that the transport of Escherichia coli strains harvested from springs could be characterized by a similar set of cell characteristics and transport parameters. The hypothesis was tested by sampling springs throughout the Lubigi catchment in Kampala, Uganda. Chemo‐physical parameters in addition to total coliform concentrations were determined. Furthermore, E. coli strains were harvested, and cell properties determined. Column experiments in saturated quartz columns of 7 cm height were conducted to determine transport parameters of selected E. coli strains. Using a two‐site non‐equilibrium sorption model, transport was modelled by fitting breakthrough data in HYDRUS 1D. Results indicated faecal contamination of the springs with high concentrations of total coliforms, chloride and nitrate. Furthermore, the maximum relative E. coli concentrations (C/C0)max in the column experiments were high. Compared with our previous work on E. coli strains, collected from a pasture and from zoo animals, attachment was low. Modelling revealed that both equilibrium and kinetic sorption were not important under conditions employed in the experiments. These observations are explained by the way in which the strains were harvested: from termination points of flow lines (springs). Such strains may possess characteristics that might have influenced their transport in the subsurface leading to their low attachment efficiency and possibly contributing to the lack of influence of equilibrium and kinetic sorption characteristics. There was no significant correlation between cell properties and transport parameters. Furthermore, 58% of the tested strains were of the O21:H7 serotype, and all definable serotypes identified were associated with diseases. We speculate that this serotype may possess characteristics that allow preferential transport through the aquifers of the area. We demonstrated that bacteria harvested from termination points of flow lines compared with those obtained from pollution sources, which have not undergone transport yet, present a good option for the assessment of bacteria transport characteristics in aquifers. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

10.
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11.
Rapid spread of antibiotic resistance genes has placed them under consideration as emerging environmental contaminants. The occurrence and distribution of tetracycline resistance genes (TRG) and integrons (INT) have been monitored for 2 years in seven oyster beds located in the Altamaha River (Georgia, USA) estuary. TRG/INT profiles varied both temporally (p < 0.025) and spatially between oysters and their environment (p < 0.005) suggesting shifts in sources of contamination and selection of TRG/INT carriers by oysters. The latter was confirmed via analysis of tet(D) and tet(G) distribution between oysters and their environment. Uncommon class 3 integrons dominated the integrons’ profile in oysters. The frequency of TRG/INT incidents correlated (R2 ? 0.9) to (i) dissolved solids, (ii) potential water density, and (iii) turbidity but not to the amount of local precipitation suggesting the watershed as the dominant source of TRG/INT contamination and other than directly rainfall-caused run-offs as its environmental route.  相似文献   

12.
The distribution of faecal coliform densities found in New York Bight sediments indicated that sewage sludge material has contaminated areas extending 11 km north and 37 km south from the disposal site. A high degree of confidence for enumerating faecal coliforms in marine sediments was demonstrated by standard water methodology since 82.3% of the faecal coliform group isolated were Escherichia coli. This study also indicated that marine sediments could be stored 4 days at 4°C without appreciable changes in the faecal coliform count, and that, in situ, faecal coliforms would persist longer when sediment temperatures were low.  相似文献   

13.
Four micro‐catchment (MC) areas were identified to represent the main terrain types of a remote, sparsely populated upland valley catchment of 18 km2 in Cumbria, UK. These were improved land with good grazing (IB), steeply sloping land with rough grazing (SG), wet moorland with sparse grazing (WM) and enclosed woodland that excluded livestock and deer (EW). Each MC contained the origin of a small stream that flowed into Swindale Beck, the river draining the valley. The water quality during the 14‐month study, as judged by chemical and physical parameters, was excellent, but it could not be regarded as pristine because of the frequent presence of Cryptosporidium oocysts arising from livestock and wild mammal faeces. Oocysts (0·2–5·6 l?1) detected by genus‐specific immunofluorescent antibody were found in 32% of 188 water samples tested: ranking order EW 44%, IB 34%, Beck 30%, SG and WM 26%. Similarly, oocysts were identified in 9·5% of 1730 faecal samples. Small wild mammals (28%), calves (15·7%) and lambs (8·1%) were the dominant sources, whereas adult livestock (1·8%) and large wild mammals (4·8%) were less important. Autumn showed the highest occurrence of oocysts for both water and faecal samples. No hydrological controls were found to have a significant impact on the occurrence or concentration of oocysts in the main river or in the MCs, suggesting that their presence is controlled by seasonal changes in pathogen prevalence in the animal reservoir. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

14.
Previous studies on fish and marine mammals support the hypothesis that marine species harbor antibiotic resistance and therefore may serve as reservoirs for antibiotic-resistance genetic determinants. The aim of this study was to assess the resistance to antimicrobial agents of Gram negative strains isolated from loggerhead sea turtles (Caretta caretta). Oral and cloacal swabs from 19 live-stranded loggerhead sea turtles, with hooks fixed into the gut, were analyzed. The antimicrobial resistance of the isolates to 31 antibiotics was assessed using the disk-diffusion method. Conventional biochemical tests identified Citrobacter spp., Proteus spp., Enterobacter spp., Escherichia spp., Providencia spp., Morganella spp., Pantoea spp., Pseudomonas spp. and Shewanella spp. Highest prevalences of resistance was detected to carbenicillin (100%), cephalothin (92.6%), oxytetracycline (81.3%) and amoxicillin (77.8%). The isolates showing resistance to the widest range of antibiotics were identified as Citrobacter freundii, Proteus vulgaris, Providencia rettgeri and Pseudomonas aeruginosa. In this study, antibiotic resistant bacteria reflect marine contamination by polluted effluents and C. caretta is considered a bioindicator which can be used as a monitor for pollution.  相似文献   

15.
Guam has one of the finest limestone aquifers in the world. Located in the northern half of the island, this vital underground resource supplies the local community with about 80% of its drinking water needs. The majority of the island’s approximately 180,000 inhabitants live in the northern half of the island where significant economic growth and urban development have occurred over the last 30 years. The U.S. military has also occupied large tracts of land in this region for the past 60 years. The risks of groundwater contamination are, therefore, very real considering the population density in northern Guam and the rapid recharge rates to the underlying aquifer. Since April 1996, Guam Waterworks Authority (GWA) has regularly monitored the island’s drinking water resources for chemical and biological contaminants in accordance with the U.S. Safe Drinking Water Act requirements. This report summarizes and compares the groundwater data sets for two discrete time intervals: 1996 through 2001 and 2002 through 2007 for chemicals, and 1997(8) through 2002 and 2003 through 2007 for bacteria. Adaptive management strategies that evolved to deal with contaminant violations over this time frame are critically discussed. Overall, 95% of all GWA’s drinking water production wells were considered to be in relatively good shape from a chemical standpoint. Identified chemicals of concern were chlordane, ethylene dibromide, perchloroethylene, trichloroethylene, and nitrate. The microbiological integrity of Guam’s groundwater was, by comparison, less impressive prior to 2003 because of numerous wastewater spills, leaks, and overflows. Improved management practices introduced shortly afterward have significantly reduced the incidence of Escherichia coli contamination in recent years.  相似文献   

16.
《Marine pollution bulletin》2013,70(1-2):122-127
The prevalence of antibiotic resistance and the implicated mechanisms of resistance were evaluated in Enterococcus spp. and Escherichia coli, isolated from a total of 250 faecal samples of echinoderms collected from Azorean waters (Portugal). A total of 144 enterococci (120 Enterococcus faecium, 14 E. hirae, 8 E. faecalis, 2 E. gallinarum) and 10 E. coli were recovered. High percentages of resistance in enterococci were found for erythromycin, ampicillin, tetracyclin and ciprofloxacin. The erm(A) or erm(B), tet(M) and/or tet(L), vat(D), aac(6′)-aph(2″) and aph(3′)-IIIa genes were found in isolates resistant to erythromycin, tetracycline, quinupristin/dalfopristin, high-level gentamicin and high-level kanamycin, respectively. Resistance in E. coli isolates was detected for streptomycin, amikacin, tetracycline and tobramycin. The aadA gene was found in streptomycin-resistant isolates and tet(A) + tet(B) genes in tetracycline-resistant isolates. The data recovered are essential to improve knowledge about the dissemination of resistant strains through marine ecosystems and the possible implications involved in transferring these resistances either to other animals or to humans.  相似文献   

17.
土地利用结构与景观格局对鄱阳湖流域赣江水质的影响   总被引：4，自引：0，他引：4  
徐启渝  王鹏  王涛  舒旺  张华  齐述华 《湖泊科学》2020,32(4):1008-1019
于2015年1月和7月采集赣江干流及支流34个采样点水样,测定电导率、水化学离子、无机氮等水质指标.利用赣江流域2014年30 m分辨率的土地利用数据,以流域景观类型占比表征土地利用结构,景观指数表征景观格局;采用Pearson相关分析、Bioenv分析、Mantle检验与方差分解等方法分析流域土地利用结构与景观格局对赣江水质的影响.结果表明:上游Cl~-、Na~+浓度最高,中游电导率、Cl~-、Na~+、K~+、Ca~(2+)等水质指标最低,下游电导率、HCO_3~-、SO_4~(2-)、Mg~(2+)、Ca~(2+)、NO_3~--N等水质指标最高.居民建设用地是对水质影响最显著的单一土地利用类型.林地、水田与居民建设用地是对水质影响最显著的土地利用类型组合.平均最近邻体指数是对水质影响最显著的单一景观指数,斑块个数、斑块聚集度指数、平均最近邻体指数是对水质影响最显著的景观指数组合.枯水期土地利用结构和景观格局对水质的贡献率分别为41.1%和17.2%,景观格局对水质的贡献率(17.2%)均为和土地利用结构的交互作用,无独立贡献部分;丰水期二者对水质贡献率分别为51%、53%,交互作用部分为37%.以上结果表明,土地利用结构与景观格局都对赣江水质有较大影响,二者的交互作用在该影响中占有重要地位,且枯水期景观格局对水质的影响涵盖在与土地利用结构的交互作用中.  相似文献   

18.
Karst aquifers are susceptible to contamination by microorganisms, but relatively few studies have used bacteria as tracers. We demonstrate the utility of Escherichia coli enriched in the stable isotope nitrogen‐15 (15N) as a novel bacterial tracer. Nonpathogenic E. coli from two springs in central Kentucky were grown on 15N‐enriched media. Survival of E. coli and persistence of the isotopic signal were assessed in two sets of laboratory experiments conducted with sterilized spring water in dark microcosms at 14 °C. First, isotopically labeled bacteria survived for 130 d at concentrations within one log unit of the average initial value, and there was no significant difference in δ15N values from Day 1 to Day 130. Second, water samples with E. coli were inoculated with either of two different species of protozoa (Tetrahymena pyriformis or Colpoda steinii). During 7 d, δ15N values increased in T. pyriformis while bacterial populations decreased. In a field test, following a 2.1‐cm rainfall, 15N‐labeled E. coli, solutes (rhodamine WT dye and bromide), and latex microspheres were injected into a sinkhole approximately 530 m upgradient of a spring. Breakthrough of all tracers coincided, but microspheres were remobilized by subsequent storms, unlike other tracers. Enriched E. coli exhibited more tailing than solute tracers during the initial storm‐flow recession. These results indicate that 15N‐enriched E. coli is a viable tracer of bacterial transport in karst aquifers, although predation may attenuate the isotopic signal in systems that are not rapidly flushed.  相似文献   

19.
The use of reclaimed water and its impact on groundwater quality in the middle and southern parts of the Jordan Valley are investigated. The chemical analyses indicate that nitrate and bacteriological pollution is widespread, and thus, seriously affects groundwater use. During the study, 365 water samples were collected from wells and springs to determine the water chemistry and the extent of nitrate pollution. Three hydrochemical facies are identifed, i. e., (Ca–(Mg)–Na–HCO3), (Ca–Na–SO4–Cl) and (Ca–Na–Cl). The change of facies is accompanied by a gradual increase in the groundwater total dissolved solids (TDS), which is mainly controlled by evaporates and carbonates dissolution in the aquifer matrix. Water analyses indicate that the shallow aquifer in the study area is affected by non‐point pollution sources, primarily from natural (manure) and chemical nitrogen (N)‐fertilizers and treated wastewater used for agriculture. The concentration of nitrate in the groundwater ranges from 10 to 355 mg/L. Considerable seasonal fluctuations in groundwater quality are observed as a consequence of agricultural practices and other factors such as annual rainfall distribution and the Zarqa River flow. The noticeable levels of total coliform and Escherichia coli in the northern part of the study area may be attributed to contamination from the urban areas, intensive livestock production, and illegal dumping of sewage. Heavy metal concentrations in all samples were found to be significantly lower than the permissible limits for drinking water standards.  相似文献   

20.
Rapid changes in spring water quality in karst areas due to rapid recharge of bacterially contaminated water are a major concern for drinking water suppliers and users. The main objective of this study was to use field experiments with fecal indicators to verify the vulnerability of a karst spring to pathogens, as determined by using a numerical modeling approach. The groundwater modeling was based on linear storage models that can be used to simulate karst water flow. The vulnerability of the karst groundwater is estimated using such models to calculate criteria that influence the likelihood of spring water being affected by microbial contamination. Specifically, the temporal variation in the vulnerability, depending on rainfall events and overall recharge conditions, can be assessed and quantified using the dynamic vulnerability index (DVI). DVI corresponds to the ratio of conduit to diffuse flow contributions to spring discharge. To evaluate model performance with respect to predicted vulnerability, samples from a spring were analyzed for Escherichia coli, enterococci, Clostridium perfringens, and heterotrophic plate count bacteria during and after several rainfall events. DVI was shown to be an indication of the risk of fecal contamination of spring water with sufficient accuracy to be used in drinking water management. We conclude that numerical models are a useful tool for evaluating the vulnerability of karst systems to pathogens under varying recharge conditions  相似文献   

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