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Wu T, Liu Z, Zhu D, Chen Y. Effect of the particle size and surface area on Escherichia coli attachment to mineral particles in fresh water. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2019; 54:1219-1226. [PMID: 31230514 DOI: 10.1080/10934529.2019.1632625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 06/09/2019] [Accepted: 06/11/2019] [Indexed: 06/09/2023]
Abstract
The objective of this study was to assess the effects of the particle size and specific surface area (SSA) on the attachment of Escherichia coli to sediment particles. To exclude the effect of different sediment mineral compositions, pure minerals were used, and three typical suspended sediment (<62 μm) components, quartz, K-feldspar and calcite, were separated into four groups with different grain size distributions. Equilibrium attachment experiments covering common E. coli concentrations in surface water were conducted for each group. The results show that the finer fractions of each pure mineral had the greatest attachment capacity. Different mineral properties were measured, as well as an author-defined parameter (SSA_a), which was calculated by integrating the particle size distribution and only reflected the microscopic surface areas accessible to E. coli cells (∼1 μm) while excluding the effects of nanoscopic pores (5-10 nm). Pearson correlation and partial correlation analyses suggested that the partition coefficient (Kd) was positively correlated with the clay content (CC) and SSA_a (P < 0.01). Stepwise multiple regression analysis suggested that SSA_a was the dominant factor (P < 0.01) and was a better explanatory variable than CC. Moreover, in addition to SSA_a, the zeta potential and SSA also partially explained the results (P < 0.05).
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Affiliation(s)
- Tao Wu
- State Key Laboratory of Hydroscience and Engineering, Tsinghua University , Beijing , China
| | - Zhongxiang Liu
- State Key Laboratory of Hydroscience and Engineering, Tsinghua University , Beijing , China
| | - Dejun Zhu
- State Key Laboratory of Hydroscience and Engineering, Tsinghua University , Beijing , China
| | - Yongcan Chen
- State Key Laboratory of Hydroscience and Engineering, Tsinghua University , Beijing , China
- Southwest University of Science and Technology , 59 Qinglong Road , Mianyang , Sichuan , China
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Vignesh S, Dahms HU, Emmanuel KV, Gokul MS, Muthukumar K, Kim BR, James RA. Physicochemical parameters aid microbial community? A case study from marine recreational beaches, Southern India. ENVIRONMENTAL MONITORING AND ASSESSMENT 2014; 186:1875-1887. [PMID: 24292984 DOI: 10.1007/s10661-013-3501-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 10/23/2013] [Indexed: 06/02/2023]
Abstract
A total of 176 (water and sediment) samples from 22 stations belonging to four different (urban, semi-urban, rural, and holy places) human habitations of Tamil Nadu beaches were collected and analyzed for physiochemical and microbial parameters during 2008-2009. Bacterial counts were two- to tenfold higher in sediments than in water due to strong bacterial aggregations by dynamic flocculation and rich organic content. The elevated bacterial communities during the monsoon explain rainfalls and several other wastes from inlands. Coliform counts drastically increased at holy and urban places due to pilgrimage and other ritual activities. Higher values of the pollution index (PI) ratio (>1) reveals, human fecal pollutions affect the water quality. The averaged PI ratio shows a substantial higher microbial contamination in holy places than in urban areas and the order of decreasing PI ratios observed were: holy places > urban areas > semi-urban areas > rural areas. Correlation and factor analysis proves microbial communities were not related to physicochemical parameters. Principal component analysis indicates 55.32 % of the total variance resulted from human/animal fecal matters and sewage contaminants whereas 19.95 % were related to organic contents and waste materials from the rivers. More than 80 % of the samples showed a higher fecal coliform and Streptococci by crossing the World Health Organization's permissible limits.
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Affiliation(s)
- Sivanandham Vignesh
- Department of Marine Science, Bharathidasan University, Tiruchirappalli, 620024, Tamil Nadu, India
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Zhou D, Bi CJ, Chen ZL, Yu ZJ, Wang J, Han JC. Phosphorus loads from different urban storm runoff sources in southern China: a case study in Wenzhou City. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2013; 20:8227-8236. [PMID: 23690078 DOI: 10.1007/s11356-013-1800-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 05/01/2013] [Indexed: 06/02/2023]
Abstract
Storm runoff from six types of underlying surface area during five rainfall events in two urban study areas of Wenzhou City, China was investigated to measure phosphorus (P) concentrations and discharge rates. The average event mean concentrations (EMCs) of total phosphorus (TP), total dissolved phosphorus (TDP), and particulate phosphorus (PP) ranged from 0.02 to 2.5 mg · L(-1), 0.01 to 0.48 mg · L(-1), and 0.02 to 2.43 mg · L(-1), respectively. PP was generally the dominant component of TP in storm runoff, while the major form of P varied over time, especially in roof runoff, where TDP made up the largest portion in the latter stages of runoff events. Both TP and PP concentrations were positively correlated with pH, total suspended solids (TSS), and biochemical oxygen demand (BOD)/chemical oxygen demand (COD) concentrations (p<0.01), while TDP was positively correlated with BOD/COD only (p<0.01). In addition, the EMCs of TP and PP were negatively correlated with maximum rainfall intensity (p<0.05), while the EMCs of TDP positively correlated with the antecedent dry weather period (p<0.05). The annual TP emission fluxes from the two study areas were 367.33 and 237.85 kg, respectively. Underlying surface type determined the TP and PP loadings in storm runoff, but regional environmental conditions affected the export of TDP more significantly. Our results indicate that the removal of particles from storm runoff could be an effective measure to attenuate P loadings to receiving water bodies.
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Affiliation(s)
- Dong Zhou
- Department of Environmental Sciences, School of Resources and Environmental Science, East China Normal University, Shanghai, 200241, China
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Dickenson JA, Sansalone JJ. Distribution and disinfection of bacterial loadings associated with particulate matter fractions transported in urban wet weather flows. WATER RESEARCH 2012; 46:6704-6714. [PMID: 22244969 DOI: 10.1016/j.watres.2011.12.039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 11/21/2011] [Accepted: 12/19/2011] [Indexed: 05/31/2023]
Abstract
Urban runoff is a resource for reuse water. However, runoff transports indicator and pathogenic organisms which are mobilized from sources of fecal contamination. These organisms are entrained with particulate matter (PM) that can serve as a mobile substrate for these organisms. Within a framework of additional treatment for reuse of treated runoff which requires the management of PM inventories in unit operations and drainage systems there is a need to characterize organism distributions on PM and the disinfection potential thereof. This study quantifies total coliform, Escherichia coli, fecal streptococcus, and enterococcus generated from 25 runoff events. With the ubiquity and hetero-dispersivity of PM in urban runoff this study examines organism distributions for suspended, settleable and sediment PM fractions differentiated based on PM size and transport functionality. Hypochlorite is applied in batch to elaborate inactivation of PM-associated organisms for each PM fraction. Results indicate that urban runoff bacterial loadings of indicator organisms exceed U.S. wastewater reuse, recreational contact, and Australian runoff reuse criteria as comparative metrics. All monitored events exceeded the Australian runoff reuse criteria for E. coli in non-potable residential and unrestricted access systems. In PM-differentiated events, bacteriological mobilization primarily occurred in the suspended PM fraction. However, sediment PM shielded PM-associated coliforms at all hypochlorite doses, whereas suspended and settleable PM fractions provide less shielding resulting in higher inactivation by hypochlorite.
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Affiliation(s)
- Joshua A Dickenson
- Engineering School of Sustainable Infrastructure and Environment (ESSIE), University of Florida, 217 Black Hall, Gainesville, FL 32611, USA
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Ahn JH. Size distribution and settling velocities of suspended particles in a tidal embayment. WATER RESEARCH 2012; 46:3219-3228. [PMID: 22507251 DOI: 10.1016/j.watres.2012.03.038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 03/11/2012] [Accepted: 03/20/2012] [Indexed: 05/31/2023]
Abstract
Field studies were carried out to investigate seasonal and bay-wide variations in the particle size distributions (PSDs) and settling velocities of suspended particles in Newport Bay, the second largest tidal embayment in southern California. Maximum Entropy Classification (MEC) of the data identified three PSD groups: (1) suspended particles with a single mode around 10-20 μm (Group 1), (2) suspended particles with a single mode similar to Group 1, but shifted to smaller particle sizes (Group 2), and (3) suspended particles with a coarse mode at around 100 μm (Group 3). The three PSD groups have distinct seasonal and spatial patterns, and different size-settling velocity relationships, consistent with the hypothesis that Newport Bay longitudinally fractionates allochthonous particles from its tributaries by both size and settling velocity, and generates large and fast settling autochthonous particles, probably in the form of biological debris. Particle concentrations in Groups 1 and 2 are significantly correlated with fecal indicator bacteria, suggesting possible linkages between fecal pollution and particle transfer in this tidal embayment.
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Affiliation(s)
- Jong Ho Ahn
- Division of Water and Environment, Korea Environment Institute, Seoul, South Korea.
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Jofre J, Blanch AR. Feasibility of methods based on nucleic acid amplification techniques to fulfil the requirements for microbiological analysis of water quality. J Appl Microbiol 2011; 109:1853-67. [PMID: 20722877 DOI: 10.1111/j.1365-2672.2010.04830.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Molecular methods based on nucleic acid recognition and amplification are valuable tools to complement and support water management decisions. At present, these decisions are mostly supported by the principle of end-point monitoring for indicators and a small number of selected measured by traditional methods. Nucleic acid methods show enormous potential for identifying isolates from conventional culture methods, providing data on cultivable and noncultivable micro-organisms, informing on the presence of pathogens in waters, determining the causes of waterborne outbreaks, and, in some cases, detecting emerging pathogens. However, some features of water microbiology affect the performance of nucleic acid-based molecular techniques and thus challenge their suitability for routine water quality control. These features include the variable composition of target water samples, the generally low numbers of target micro-organisms, the variable water quality required for different uses and the physiological status or condition of such micro-organisms. The standardization of these molecular techniques is also an important challenge for its routine use in terms of accuracy (trueness and precision) and robustness (reproducibility and reliability during normal usage). Most of national and international water regulations recommend the application of standard methods, and any new technique must be validated respect to established methods and procedures. Moreover, molecular methods show a high cost-effectiveness value that limits its practicability on some microbial water analyses. However, new molecular techniques could contribute with new information or at least to supplement the limitation of traditional culture-based methods. Undoubtedly, challenges for these nucleic acid-based methods need to be identified and solved to improve their feasibility for routine microbial water monitoring.
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Affiliation(s)
- J Jofre
- Department of Microbiology, School of Biology, University of Barcelona, Barcelona, Spain
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Kim G, Hur J. Mortality rates of pathogen indicator microorganisms discharged from point and non-point sources in an urban area. J Environ Sci (China) 2010; 22:929-933. [PMID: 20923108 DOI: 10.1016/s1001-0742(09)60200-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
This research measured the mortality rates of pathogen indicator microorganisms discharged from various point and non-point sources in an urban area. Water samples were collected from a domestic sewer, a combined sewer overflow, the effluent of a wastewater treatment plant, and an urban river. Mortality rates of indicator microorganisms in sediment of an urban river were also measured. Mortality rates of indicator microorganisms in domestic sewage, estimated by assuming first order kinetics at 20 degrees C were 0.197 day(-1), 0.234 day(-1), 0.258 day(-1) and 0.276 day(-1) for total coliform, fecal coliform, Escherichia coli, and fecal streptococci, respectively. Effects of temperature, sunlight irradiation and settlement on the mortality rate were measured. Results of this research can be used as input data for water quality modeling or can be used as design factors for treatment facilities.
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Affiliation(s)
- Geonha Kim
- Department of Civil and Environmental Engineering, Hannam University, Ojungdong, Daedukku, Daejeon 306-791, Korea.
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Krometis LAH, Dillaha TA, Love NG, Mostaghimi S. Evaluation of a filtration/dispersion method for enumeration of particle-associated Escherichia coli. JOURNAL OF ENVIRONMENTAL QUALITY 2009; 38:980-986. [PMID: 19329686 DOI: 10.2134/jeq2007.0037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The transport processes of microorganisms in storm-generated flows have not been clearly elucidated, limiting the ability of computational models to effectively design and evaluate watershed remediation plans. Although several studies have identified association with particulates as a critical factor in predicting microbial transport and fate, no generally accepted method exists for the identification of the planktonic and particle-associated fractions of microorganisms in water samples. In this study, a filtration/dispersion method proposed for quantification of these fractions was verified using laboratory-composed samples of bovine Escherichia coli and sterile topsoil. A statistical experimental design allowed quantification of potential sources of experimental error (e.g., filter retention, die-off), although no significant sources of methodological error were identified. On average, 78% of E. coli cells were particle associated after 1 h of contact time. Further application of the method was illustrated by an isotherm experiment examining the association of a bovine strain of E. coli with sterile topsoil. Further examination of this method in laboratory or field-based studies of microbial partitioning between the planktonic and particulate phases in surface runoff appears justified.
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Affiliation(s)
- Leigh-Anne H Krometis
- Dep. of Environmental Sciences, Gillings School of Global Public Health, Univ. of North Carolina, Chapel Hill, NC 27599-7431, USA.
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Garcia-Armisen T, Servais P. Partitioning and fate of particle-associated E. coli in river waters. WATER ENVIRONMENT RESEARCH : A RESEARCH PUBLICATION OF THE WATER ENVIRONMENT FEDERATION 2009; 81:21-28. [PMID: 19280896 DOI: 10.2175/106143008x304613] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Attachment of fecal bacteria to suspended matter in the water column has important implications for its fate in rivers. We examined the part of Escherichia coli (E. coli) associated with suspended matter in natural river water samples, using a combination of 5-microm filtration and beta-D-glucuronidase (GLUase) assay to estimate the E. coli abundance and attachment. We observed that the fraction of particle-associated E. coli was positively correlated with suspended matter concentration. The settling rate of particle-associated E. coli was found to be positively correlated with suspended matter concentration for samples with suspended matter content lower than 50 mg/L. For samples with higher suspended matter concentration, the settling rate was quite constant (0.066 m/h, on average). In batch experiments using river waters, we observed that free E. coli had a decay rate approximately 2 times higher than particle-associated E. coli. This information can be used to improve the models on the fate of E. coli in rivers.
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Affiliation(s)
- Tamara Garcia-Armisen
- Ecologie des Systèmes Aquatiques, Université Libre de Bruxelles, Bruxelles, Belgique.
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Cantwell RE, Hofmann R. Inactivation of indigenous coliform bacteria in unfiltered surface water by ultraviolet light. WATER RESEARCH 2008; 42:2729-2735. [PMID: 18316110 DOI: 10.1016/j.watres.2008.02.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2007] [Revised: 01/22/2008] [Accepted: 02/02/2008] [Indexed: 05/26/2023]
Abstract
This study examined the potential for naturally occurring particles to protect indigenous coliform from ultraviolet (UV) disinfection in four surface waters. Tailing in the UV dose-response curve of the bacteria was observed in 3 of the 4 water samples after 1.3-2.6-log of log-linear inactivation, implying particle-related protection. The impact of particles was confirmed by comparing coliform UV inactivation data for parallel filtered (11 microm pore-size nylon filters) and unfiltered surface water. In samples from the Grand River (UVT: 65%/cm; 5.4 nephelometric turbidity units (NTU)) and the Rideau Canal (UVT: 60%/cm; 0.84 NTU), a limit of approximately 2.5 log inactivation was achieved in the unfiltered samples for a UV dose of 20 mJ/cm2 while both the filtered samples exhibited >3.4-log inactivation of indigenous coliform bacteria. The results suggest that particles as small as 11 microm, naturally found in surface water with low turbidity (<3NTU), are able to harbor indigenous coliform bacteria and offer protection from low-pressure UV light.
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Affiliation(s)
- Raymond E Cantwell
- Department of Civil Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario, Canada M5S 1A4
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Boving TB, Stolt MH, Augenstern J, Brosnan B. Potential for localized groundwater contamination in a porous pavement parking lot setting in Rhode Island. ACTA ACUST UNITED AC 2007. [DOI: 10.1007/s00254-007-1008-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Templeton MR, Andrews RC, Hofmann R. Impact of iron particles in groundwater on the UV inactivation of bacteriophages MS2 and T4. J Appl Microbiol 2006; 101:732-41. [PMID: 16907824 DOI: 10.1111/j.1365-2672.2006.02980.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS To investigate the impact of iron particles in groundwater on the inactivation of two model viruses, bacteriophages MS2 and T4, by 254-nm ultraviolet (UV) light. METHODS AND RESULTS One-litre samples of groundwater with high iron content (from the Indianapolis Water Company, mean dissolved iron concentration 1.3 mg l(-1)) were stirred vigorously while exposed to air, which oxidized and precipitated the dissolved iron. In parallel samples, ethylenediaminetetra-acetic acid (EDTA) was added to chelate the iron and prevent formation of iron precipitate. The average turbidity in the samples without EDTA (called the 'raw' samples) after 210 min of stirring was 2.7 +/- 0.1 NTU while the average turbidity of the samples containing EDTA (called the 'preserved' samples) was 1.0 +/- 0.1 NTU. 'Raw' and 'preserved' samples containing bacteriophage MS2 were exposed to 254-nm UV light at doses of 20, 40, or 60 mJ (cm(2))(-1), while samples containing bacteriophage T4 were exposed to 2 or 5 mJ (cm(2))(-1), using a low pressure UV collimated beam. The UV inactivation of both phages in the 'raw' groundwater was lower than in the EDTA-'preserved' groundwater to a statistically significant degree (alpha = 0.05), due to the association of phage with the UV-absorbing iron precipitate particles. A phage elution technique confirmed that a large fraction of the phage that survived the UV exposures were particle-associated. CONCLUSIONS Phages that are associated with iron oxide particles in groundwater are shielded from UV light to a measurable and statistically significant degree at a turbidity level of 2.7 NTU when the phage particle association is induced under experimental conditions. SIGNIFICANCE AND IMPACT OF THE STUDY While the particle association of the phage in this study was induced experimentally, the findings provide further evidence that certain particles in natural waters and wastewaters (e.g. iron oxide particles) may have the potential to shield viruses from UV light.
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Affiliation(s)
- M R Templeton
- Department of Civil Engineering, University of Toronto, Toronto, Ontario, Canada.
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Kim G, Choi E, Lee D. Diffuse and point pollution impacts on the pathogen indicator organism level in the Geum River, Korea. THE SCIENCE OF THE TOTAL ENVIRONMENT 2005; 350:94-105. [PMID: 16227076 DOI: 10.1016/j.scitotenv.2005.01.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2004] [Accepted: 01/12/2005] [Indexed: 05/04/2023]
Abstract
The pathogens originating from diffuse pollution have raised much concern recently. In many countries, pathogen levels are monitored in surface water by measuring the pathogen indicator organism level, which indicates the concentration of pathogen associated microorganisms to determine contamination. Among indicator organisms, total coliform, fecal coliform, and Escherichia coli were selected for study, and their concentration as well as their flow rate were monitored at monitoring stations from October, 2001 to April, 2003. Monitoring stations include six sampling stations in the Geum River, two small watersheds used for forestry and agricultural land, one large wastewater treatment plant, one separate sewer overflow site, and one separate sewer overflow site in the Geum River basin. The coliform concentration of the combined sewer overflow was the highest, followed by the runoff from agricultural land use, the separate sewer overflow, and the runoff from forestry land use. The Pearson correlation coefficient for flow rate against total coliform concentration was 0.71 and was significant at 0.01 level, while the Pearson coefficient for other water quality constituents showed weak correlation (-0.36 to +0.37) against flow rate. Coliform concentration showed higher correlation against suspended solid concentration or flow rate during storm flow condition than during low flow condition. Two different relationship lines could explain the relationships between the flow rate and coliform loadings. Load duration curve technique was presented to assess the relative contributions of diffuse and point source pollution to the pathogen level at monitoring sites in the Geum River.
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Affiliation(s)
- Geonha Kim
- Department of Civil and Environmental Engineering, Hannam University, Ojungdong, Daejon, South Korea, 306-791.
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Templeton MR, Andrews RC, Hofmann R. Inactivation of particle-associated viral surrogates by ultraviolet light. WATER RESEARCH 2005; 39:3487-500. [PMID: 16081130 DOI: 10.1016/j.watres.2005.06.010] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2005] [Revised: 06/11/2005] [Accepted: 06/16/2005] [Indexed: 05/03/2023]
Abstract
This study investigated whether colloid-sized particles can enmesh and protect viruses from 254-nm ultraviolet (UV) light and sought to determine the particle characteristics (e.g. size, chemical composition) that are most relevant in causing a protective effect. Two viral surrogates (MS2 coliphage and bacteriophage T4), three types of particles (kaolin clay, humic acid powder, and activated sludge), two coagulants (alum and ferric chloride), two filtration conditions (none and 0.45 microm), and two UV doses (40 and 80 mJ/cm2 for MS2 coliphage; 2 and 7 mJ/cm2 for bacteriophage T4) were considered in a series of bench-scale UV collimated beam experiments. Transmission electron microscopy was used to qualitatively confirm the phage particle-association after coagulation. Humic acid and activated sludge floc particles shielded both viral surrogates to a statistically significant degree (with >99% confidence) relative to particle-free control conditions, while the kaolin clay particles provided no significant protection. The results of the study suggest that particles <2 microm in diameter are large enough to protect viruses from UV light and that particulate chemical composition (e.g. UV-absorbing organic content) may be a critical factor in the survival of particle-associated viruses during UV disinfection.
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Affiliation(s)
- Michael R Templeton
- Department of Civil Engineering, University of Toronto, Toronto, Ont., Canada M5S 1A4.
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Muirhead RW, Collins RP, Bremer PJ. Erosion and subsequent transport state of Escherichia coli from cowpats. Appl Environ Microbiol 2005; 71:2875-9. [PMID: 15932980 PMCID: PMC1151858 DOI: 10.1128/aem.71.6.2875-2879.2005] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Processes by which fecal bacteria enter overland flow and their transportation state to surface waters are poorly understood, making the effectiveness of measures designed to intercept this pathway, such as vegetated buffer strips, difficult to predict. Freshly made and aged (up to 30 days) cowpats were exposed to simulated rainfall, and samples of the cowpat material and runoff were collected. Escherichia coli in the runoff samples were separated into attached (to particles) and unattached fractions, and the unattached fraction was analyzed to determine if the cells were clumped. Within cowpats, E. coli grew for 6 to 14 days, rather than following a typical logarithmic die-off curve. E. coli numbers in the runoff correlated with numbers inside the cowpat. Most of the E. coli organisms eroded from the cowpats were transported as single cells, and only a small percentage (about 8%) attached to particles. The erosion of E. coli from cowpats and the state in which the cells were transported did not vary with time within a single rainfall event or over time as the cowpats aged and dried out. These findings indicate that cowpats can remain a significant source of E. coli in overland flow for more than 30 days. As well, most of the E. coli organisms eroded from cowpats will occur as readily transportable single cells.
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