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1.
Huntington Beach, California, one of the most popular surfing spots in the world, is plagued by sporadic, elevated levels of fecal bacteria. To assist with pollution source identification, we analyzed antibiotic resistance patterns (ARPs) of enterococci from four known sources (bird feces, urban runoff, coastal marsh sediment and sewage effluent from local sanitation district) and one unknown source (seawater) using seven antibiotics at four concentrations each. Of 2491 enterococci tested, all were resistant to at least one antibiotic at some level. Discriminant analysis indicated that the average correct classification rates for bird feces and urban runoff sources were above 80%. Sewage effluent contained mixed fecal sources. Sixty-four percent of the sewage isolates classified with the sewage category, while the other 35% of isolates were assigned evenly across the other three categories. When enterococci isolated from the seawater were classified using the known ARP database, it was evident that bird feces were the source of surf zone contamination on some days while the coastal salt marsh and sewage plume may have impacted the surf zone water quality to various degrees during other times.  相似文献   

2.
Oxytetracycline-resistant bacteria were isolated from a mariculture farm in China, and accounted for 32.23% and 5.63% of the total culturable microbes of the sea cucumber and the sea urchin rearing waters respectively. Marine vibrios, especially strains related to Vibrio splendidus or V. tasmaniensis, were the most abundant resistant isolates. For oxytetracycline resistance, tet(A), tet(B) and tet(D) genes were detected in both sea cucumber and sea urchin rearing ponds. The dominant resistance type for V. tasmaniensis-like strains was the combination of both tet(A) and tet(B) genes, while the major resistance type for V. splendidus-like strains was a single tet(D) gene. Most of the sea cucumber tet-positive isolates harbored a chloramphenicol-resistance gene, either cat IV or cat II, while only a few sea urchin tet-positive isolates harbored a cat gene, actually cat IV. The coexistence of tet and cat genes in the strains isolated from the mariculture farm studied was helpful in explaining some of the multi-resistance mechanisms.  相似文献   

3.
A preliminary study of sediments and overlying water samples obtained at the approximate centre of the sewage sludge bed in the New York Bight, revealed significant numbers of coliforms resistant to antibiotics and heavy metals. Some of the isolates were shown to transfer antibiotic resistance during conjugation with a recipient strain of Salmonella gallinarum. The selection of bacterial populations resistant to antimicrobials may be significant in the ecology of this impoverished area, and requires further study.  相似文献   

4.
《水文科学杂志》2013,58(3):543-555
Abstract

The contact between freshwater and seawater in coastal aquifers is studied using a relatively simple model for homogeneous aquifers. However, for real aquifers it is not so simple. The desalination plant built to supply water to the city of Almería is situated over the aquifer in the southern part of the River Andarax Delta. Its design capacity is 1100 L s?1, and it is supplied from boreholes pumping water from beneath the freshwater—seawater contact in this aquifer. Well logs kept over a period of two years have allowed us to accurately define the interface geometry of the freshwater—seawater contact. Lithological data collected from 31 boreholes have also indicated the existence of strata with low hydraulic conductivity, within others of high conductivity. During a simultaneous pumping test of six wells with 690 L s?1 total discharge, electrical conductivity measurements showed the influx of seawater 6–10 m below sea level and a drawdown of the interface in the piezometers closest to the pumping wells.  相似文献   

5.
The aim of this work was to find out how far the Nervion Estuary serves as a reservoir of R plasmids and/or for their dissemination. The fecal pollution bacterial indicator population was estimated along the estuary and 167 coliform isolates were assayed for resistance to 16 antibiotics. About sixty-nine per cent of the coliform isolates were antibiotic-resistant and forty-two per cent of these were simultaneously resistant to three or more of 16 antibiotics tested. Furthermore, 31.5% of enterobacterial strains resistant to any of the antibiotics tested could transfer their resistance determinants in conjugal matings. Most of the transferred plasmids confer resistance to ampicillin or to other β-lactamic antibiotics and several codify resistance to tetracyclin, chloramphenicol of fosfomycin. Taking account of the coliforms density found and the ratio of these isolates able to transfer R plasmids, an average of 5 × 103 coliform strains able to transfer R plasmids in 100 ml of water was obtained. This amount must indicate a significant potential public health risk because these polluted waters get into an area with intensive fishing and recreational use.  相似文献   

6.
The influence of small amounts of clay minerals on the hydraulic conductivity of sandy aquifer was investigated by laboratory experiments. Admixture of up to 1.5% by weight of clay minerals to sand did not cause any measurable decrease of hydraulic conductivity for seawater. Increasing the clay fraction from 1.5% to 10% decreased hydraulic conductivity by one order of magnitude. Montmorillonite caused the strongest decrease; the effect of kaolinite and illite was only half as large. When seawater was flushed by freshwater, hydraulic conductivity of the montmorillonite-sand mixture decreased drastically. However, flushing with freshwater did not measurably affect the hydraulic conductivity of an illite-sand or kaolinite-sand mixture. The explanation for this behaviour is the capability of various types of clay to adsorb different quantities of water between their platelets which induces a gel-droplet formation process. This is governed by the chemical composition and the ionic strength of the solution.  相似文献   

7.
Microorganisms resistant to 1–500 ppm cadmium were isolated over an 11 month period from sediments at the sewage sludge, dredge spoils and industrial acid waste disposal sites, as well as at an estuarine outflow to the New York Bight apex. Tests for antibiotic resistance in these isolates revealed that 94% of the isolates were resistant to one or more antibiotics and that 91% of the original isolates could be characterized by multiple drug resistance. Different selective pressures may account for the various genera and antimicrobial resistance patterns observed. The possibility of extrachromosomal linkage of cadmium and streptomycin resistance is discussed.  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.
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   

10.
A total of 51 potential pathogenic vibrios were isolated from moribund silver sea bream (Sparus sarba) collected from fish farms in Hong Kong. Using the API 20E system and the scheme of Alsina and Blanch (1994), 7 species were identified from all isolates. These species were Vibrio alginolyticus (24 strains), Vibrio vulnificus (12 strains), Vibrio parahaemolyticus (7 strains), Vibrio logei (4 strains), Vibrio pelagius II (2 strains), Vibrio fluvialis (1 strain) and Vibrio meditterranei (1 strain). The three dominant species (V. alginolyticus, V. vulnificus and V. parahaemolyticus) were confirmed to be virulent to sea bream by experimental challenge.

All isolates were screened for plasmid DNA by agarose gel electrophoresis and tested for susceptibility to 16 antibiotics by the agar dilution method. Of the 51 isolates examined, all strains were sensitive to ceftriaxone, streptomycin, nalidixic acid and rifampicin, and almost all were sensitive to ceftazidime, netilimicin, chloramphenicol and sulfamethoxazole. Most isolates were resistant to ampicillin (60.8%), cefuroxime (66.7%), amikacin (55%), kanamycin (58.8%) and trimethoprim (76.5%). Fifteen of the 51 isolates harboured 1–4 plasmids, with sizes ranging from 9 to 123 kb. Both the plasmids and the associated antibiotic resistance (ampicillin, cefuroxime and trimethoprim) of 9 isolates could be transferred to a recipient by single-step conjugation. However, the frequencies were very low, ranging from 10−11 to 10−9. The present results indicate that resistance to these antibiotics is chromosomal.  相似文献   


11.
We assessed the occurrence of pollution indicators and antibiotic resistant bacterial isolates from water and sediment samples of three different eco-regions of the Chennai coast between March - May of 2010. Total of 960 bacterial strains belonging to four genera were isolated which show the highest frequencies of resistance to vancomycin (53.6%) and penicillin (52.6%) (except Enterococcus sp., which is highly resistant to erythromycin) and lowest frequencies of resistance to chloramphenicol (3.43%), ciprofloxacin (3.95%), gentamicin (4.68%), and tetracycline (6.97%). The E. coli, Vibrio sp., Salmonella sp. and Enterococcus sp. show high frequency of resistance to 2-5 antibacterials of 60.4%, 45.83%, 69.16% and 46.6%, respectively. High pollution indices (PI - 6.66-14.06) and antibiotic resistance indices (ARI - 0.29-0.343) indicate that the coastal environment is highly exposed to antibiotic sources that suggesting to avoid direct contact.  相似文献   

12.
This paper provides for the first time an experimental study where the impact of sea‐level fluctuations and inland boundary head‐level variations on freshwater–saltwater interface toe motion and transition zone dynamics was quantitatively analysed under transient conditions. The experiments were conducted in a laboratory flow tank where various (inland and coastal) head changes were imposed to the system and the response of the key seawater intrusion parameters was analysed with high spatial and temporal resolution. Two homogeneous aquifer systems of different grain size were tested. The numerical code SEAWAT was used for the validation. The results show that in cases of sea‐level variations, the intruding wedge required up to twice longer time to reach a new steady‐state condition than the receding wedge, which thereby extend the theory of timescale asymmetry between saltwater intrusion and retreat processes in scenarios involving sea‐level fluctuations. The intruding and receding rates of the saltwater wedge were respectively similar in the scenario involving sea‐level and the freshwater‐level changes, despite change in transmissivity. The results show that, during the intrusion phase, the transition zone remains relatively insensitive, regardless of where the boundary head change occurs (i.e., freshwater drop or sea‐level rise) or its magnitude. By contrast, a substantial widening of the transition zone was observed during the receding phase, with almost similar amplitude in the scenario involving a rise of the freshwater level compared with that caused by a drop of the saltwater level, provided that an equivalent absolute head change magnitude was used. This transition zone widening (occurring during saltwater retreat) was greater and extended over longer period in the low hydraulic conductivity aquifer, for both freshwater‐level rise and sea‐level drop scenarios. The concentration maps revealed that the widening mechanism was also enhanced by the presence of some freshwater sliding and into the wedge during saltwater retreat, which was thereafter sucked upward towards the interface because of density difference effects.  相似文献   

13.
Bacterial counts for total coliforms and E. coli in estuaries are normally orders of magnitude greater at the freshwater end than at the seaward end and tidal movements and variations in freshwater flows produce continual change in the freshwater/seawater mix--this causes the bacterial counts to vary greatly throughout the estuary and the complexity creates difficulty in appraising or assessing the bacterial counts (i.e. difficulties arise when deciding if the bacterial counts for estuarine water samples are within an acceptable range--relative to their corresponding salinities). The situation is further complicated in estuaries where sewage is discharged directly. Microbiological criteria and indices that can be used in a practical way to overcome these difficulties were developed. The procedure is summarised as follows: 1. Primary criteria are proposed for total coliform and for E. coli bacteria in the freshwater at the head of the estuary and in full seawater at the mouth of the estuary. 2. For estuarine or transitional waters (i.e. waters with salinity ranging from 0 per thousand to 35 per thousand), distinct criteria are calculated for each individual sample--with a separate criterion for total coliforms and for E. coli--the individual criteria are founded on the primary criteria and vary with salinity on a pro-rata or linear basis. 3. Finally, the Microbiological Index for each result is obtained by dividing the actual bacterial count by the corresponding criterion--the acceptable Index is then equal to 1--at any salinity (i.e. where the Index is <1 then the bacterial count complies with the criterion, and where the Index is >1 then the count breaches the criterion). The Index also indicates the extent of the compliance or non-compliance with the corresponding criteria. An example of the application of the Microbiological Index is also presented--including examples of graphs that demonstrate how microbiological data for estuarine waters can be summarised and presented.  相似文献   

14.
《Marine pollution bulletin》2014,78(1-2):118-129
There is a growing concern of seawater intrusion to freshwater aquifers due to groundwater overexploitation in the eastern coastal belt of Southern India. The problem becomes complex in the regions where industrial effluents are also contaminating the freshwater aquifers. In order to understand the hydrochemical complexity of the system, topographic elevation, static water level measurements, major ion chemistry, ionic cross plots, water type contours and factor analysis were applied for 144 groundwater samples of shallow and deep sources from Quaternary and Tertiary coastal aquifers, located within the industrial zone of 25 km2 area near Cuddalore, Southern India. The ionic cross plots indicates dissolution of halite minerals from marine sources and seawater mixing into inland aquifers up to the level of 9.3%. The factor analysis explains three significant factors totaling 86.3% of cumulative sample variance which includes varying contribution from marine, industrial effluent and freshwater sources.  相似文献   

15.
从沉积物特征谈太湖的演变   总被引：8，自引：5，他引：3  
通过太湖湖底淤泥层中的微体古生物及其物理化学分析,在西太潮W1孔发现多门类海相化石。海相化石出现的时间约在1100—5000aB.P.之间。据此提出西太湖在全新世期间曾遭受海侵,因而支持了太湖形成于泻湖的说法,同时,还提出海水进入太湖的时间,比以往学者推测的早2000多年。  相似文献   

16.
Antibiotic resistance of heterotrophic bacteria isolated from a sandy beach in Sopot, at the Southern Baltic Sea coast was determined. The levels of resistance of bacteria to various antibiotics differed considerably. Bacteria inhabiting the middle part of the beach and the dune were most resistant; the least resistant were bacteria isolated from the sea-beach contact zone. Generally, there were no significant differences in antibiotic resistance between pigmented and non-pigmented bacteria. Bacteria isolated from the surface layer of the sand were more resistant to the tested antibiotics than bacteria from the subsurface layers. The majority of bacterial strains were resistant to 3-8 antibiotics. Bacterial resistance to antibiotics was dependent on their chemical structure.  相似文献   

17.
Produced water is one of the largest waste products routinely discharged into the ocean from offshore oil and gas platforms. This study analyzed bacterial communities and metals in the produced water, surrounding seawater, and sediment around the Thebaud platform. The bacterial community within the produced water was different from the seawater (SAB = 13.3), but the discharge had no detectable effect on the bacterial communities in the seawater (SAB > 97). In contrast, genomic analysis of sediments revealed that the bacterial community from 250 m was different (SAB = 70) from other locations further from the discharge, suggesting that the produced water had a detectable effect on the bacterial community in the sediment closest to the discharge. These near-field sediments contained elevated concentrations of manganese and iron that are associated with the produced water effluent. The results suggested that the discharge of produced water has influenced the bacterial community structure of sediments adjacent to the platform.  相似文献   

18.
将府河从都江堰宝瓶口段至望江公园段分设9个监测点,在秋冬、春夏两季分别取水,首次建立由细菌总数、总大肠菌群数及粪大肠菌群数三个微生物学指标组成的体系,对府河两季水质进行对比监测分析,以综合评价水质、分析季节影响因素并反映出污染物来源.以都江堰宝瓶口大肠杆菌耐药率作为背景值,对整个河段的9个采样点分离纯化鉴定得到102株大肠杆菌,用K-B法进行对比药敏试验.结果表明,府河从都江堰段起,穿过成都市区后,至望江公园段细菌总数、大肠菌群数及粪大肠菌群数虽有波动,但细菌总数总体呈增加趋势,春夏季府河营养富集,水质有所降低.府河中大肠杆菌耐药性较小,β-内酰胺类耐药率在0.96％～33.33％之间,氨基糖苷类1.39％～7.84％,氟喹诺酮类11.43％～11.76％,磺胺类复方新诺明为52.78％,其中β-内酰胺类耐药性、氟喹诺酮类耐药性与源头水质有关,其余与医疗机构排放的废水及生活污水有关,此研究为控制成都府河水体中的污染防控提供了理论依据.  相似文献   

19.
Many surveys of trace contaminants of seawater are based on the supposition that the situation is static. Little is known about seasonal fluctuations in the concentrations of these contaminants and less about the cause of this variation. Fluctuation in freshwater carrying metals or sediment that will trap contaminants, changes in movements of water masses in the sea, as well as the use of trace metals by marine organisms, are all contributory factors.  相似文献   

20.
The distribution of Staphylococcus aureus and Listeria monocytogenes in the sea water and marine organisms of Peter the Great and Nha Trang bays, the phenotypic properties and antibiotic sensitivity of the isolates were studied. S. aureus was recorded from 9.3% samples in the Sea of Japan and from 20.4% samples in the South China Sea, L. monocytogenes respectively from 5.9 % and 5.8 % samples. S. aureus and L. monocytogenes found in the tropics differed in their phenotypic properties from those found in the temperate zone. Antibiotic resistance was detected in 81.8% and 71.8% of S. aureus strains and in 19% and 71.4% of L. monocytogenes strains respectively from Peter the Great Bay and from Vietnam. The results show that multiresistant strains of S. aureus and L. monocytogenes are widespread throughout Peter the Great and Nha Trang bays and present a hazard to the health of humans and marine animals.  相似文献   

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