Maximum desorption of perfluoroalkyl substances adsorbed on granular activated carbon used in full-scale drinking water treatment plants.

Activated carbon adsorption is an effective method for removing perfluoroalkyl substances (PFAS) from water. However, the observation that higher concentrations of PFAS are observed after treatment than before (i.e., desorption) is an important, unsolved issue. In this study, to elucidate PFAS desorption and its relationship with PFAS properties, we conducted solvent extraction and long-term desorption experiments using granular activated carbon (GAC) that had been loaded with PFAS in two actual drinking water treatment plants. The amount of PFAS extracted from GAC depended on the depth in the GAC filter; longer-chain and hydrophobic PFAS were present in relatively higher amounts in the shallow part compared to the deep part of the GAC filter, whereas shorter-chain and hydrophilic PFAS were present in relatively higher amounts in the deep part compared to the shallow part. This pattern was probably due to a chromatographic effect by which hydrophilic PFAS adsorbed once, subsequently desorbed, and migrated from the shallow part of the GAC filter to the deeper part. The desorption potential of PFAS to water (i.e., the maximum amount of PFAS desorbed to water per unit mass of GAC) was estimated by conducting long-term bottle-point desorption tests and analyzing the relationship between the equilibrium water-phase concentration of PFAS in a bottle containing GAC and the amount of PFAS desorbed to water per unit GAC mass. The desorption ratio (ratio of desorption potential to loading) was the highest for PFAS for which the logarithm of the octanol/water distribution coefficient (Log DOW) ranged from -1 to 1. The implication was that most of those PFAS removed by GAC were likely to return to the water as the external water-phase concentrations dropped. The decrease of the desorption ratio to 20 % as Log DOW increased suggested irreversible adsorption due to hydrophobic affinity.

Long-term removal of perfluoroalkyl substances via activated carbon process for general advanced treatment purposes.

Granular or powdered activated carbon (GAC/PAC) processes are installed in full-scale drinking water treatment plants (DWTPs) to reduce disinfection byproduct precursors, odor, ammonia, and pesticides. This study investigated the ability of GAC/PAC processes in 23 DWTPs to remove per- and polyfluoroalkyl substances (PFASs). In the GAC process, filter breakthrough of perfluoroalkyl carboxylic acids (PFCAs) occurred faster as the PFCA chain length is decreased. During periods of high water temperatures (20-29 °C), the effluent concentration of two short-chain PFCAs (C4 and C5) surpassed that of the influent after the throughput reached 5,000-7,500 bed volumes (equivalent to 2-3 months) due to desorption. However, such desorption was not observed during periods of low water temperatures (5-19 °C). Meanwhile, long-chain PFCAs were consistently removed, as the GAC was replaced before breakthrough became noticeable. PFAS removal deteriorated at a remarkably fast rate after a partial breakthrough of several tens of percent. Biological activated carbon was proved ineffective in removing PFASs due to its diminished adsorption capacity after long-term use. The PAC process, however, exhibited a slight decrease in PFCA residual (10%) at higher water temperatures (15-30 °C). The PAC dose required for a certain residual ratio was lower with an increase in the hydrophobicity of PFAS; C8-PFCA only required 20 mg/L of PAC for 50% removal, while C4-PFCA required a significantly higher dose of 100-700 mg/L. Consequently, the activated carbon process, which removes organic contaminants in surface water, was inadequate in removing PFASs, particularly those with short chains. Thus, it is recommended that GAC filters be replaced more frequently (within two months) for short-chain PFAS removal. Further, the adsorption performance of PAC must be enhanced.

Patient-reported outcomes of implant-assisted removable partial dentures with magnetic attachments using short implants: A prospective study.

Purpose Implant-assisted removable partial dentures (IARPDs) with short implants improve the oral functions of removable partial dentures (RPDs). This study aimed to compare the patient-reported outcomes of RPDs and IARPDs with short implants retained by magnetic attachments.Methods We recruited 30 participants with mandibular Kennedy Class I or II and distal extension defects of three or more teeth. RPDs, IARPDs with a healing cap, and IARPDs with a magnetic attachment were evaluated across stages using patient-reported outcomes. All participants completed questionnaires (oral health-related quality of life [OHRQoL], patient general satisfaction, and patient's denture assessment [PDA]) at each stage. The OHRQoL was evaluated using the Oral Health Impact Profile-J 54 (OHIP-J 54) score. The general patient satisfaction was evaluated using a 100 mm visual analog scale. The Wilcoxon signed-rank test and Bonferroni correction were used to evaluate differences between the groups (α=0.05).Results The OHRQoL of IARPDs was significantly higher than that of RPDs. IARPDs with a magnetic attachment had significantly better patient general satisfaction and PDA than IARPDs with a healing cap.Conclusions The OHRQoL, patient general satisfaction, and PDA were improved by IARPD with a short implant using a magnetic attachment.

A field survey on elution of lead and nickel from taps used in homes and analysis of product test results.

The elution of lead, and nickel from water supply devices into water is a potential health concern. This study was performed to examine the actual concentrations of nickel and lead in the water from taps in homes and offices, focusing on the differences between first flush and fully flushed water. The water quality management target value and water quality standard in Japan specify nickel and lead concentrations in drinking water <20 and <10 µg/L, respectively. Nickel concentration in the first flush water (100 mL) from 110 household taps revealed 22 cases (20%) > 20 µg/L, while the fully flushed water satisfied the standard after running 5000 mL of water. The nickel concentration decreased gradually in sequential sampling of each 100 mL from the taps. Lead concentration in the first flush water exceeded the standard in 32 cases (29%), while the fully flushed water was below the target value. The concentration in the first flush water tended to decrease with time since the tap installation, and this was significant after 10 years for nickel but not significant for lead. It is important to flush retained water out of the tap after several hours without use. No significant correlation was found with the volume of the test faucet in the market, but bronze-based products showed higher nickel concentrations than brass and plastic products.

National trends in pesticides in drinking water and water sources in Japan.

Although agricultural activities-especially paddy rice cultivation-are prominent in watersheds in Asian countries, few comprehensive studies have examined pesticide concentrations in water in these areas. Here, we report the concentrations of 162 pesticides in treated drinking water and source water (14,076 samples) in Japan, where rice cultivation is common, along with trends in sales of herbicides, fungicides, and insecticides from 1963 to 2016. Herbicides and fungicides-especially those used in rice farming were frequently detected in drinking water sources. The herbicide bromobutide, which is not listed in drinking water quality standards or guidelines except in Japan, as well as the widely used-and-detected bentazone, were frequently detected in source water (bromobutide and bentazone were detected at concentrations >0.1 µg/L in 31.1% and 33.8% of samples, respectively). Dymron and tefuryltrione were also detected in over 10% of samples at concentrations >0.1 µg/L. The highest observed concentration of bromobutide was 10 µg/L, and 7.5% of samples had concentrations >1 µg/L. High concentrations were also observed for halosulfuron methyl (7.9 µg/L), pyroquilon (7.0), molinate (6.8), and metominostrobin (4.6). Some of the pesticides frequently detected in source water were not detected at all in drinking water, but the main cause of the non-detection appeared to be degradation by chlorine. From the 1970s onward, sales of herbicides and fungicides with higher acceptable daily intakes (ADIs; i.e., with lower toxicity) have increased. However, the percentage of herbicides with very low ADIs (<10-2.5 mg kg-1 d-1) being shipped has also increased. Tefuryltrione, which was detected at normalized concentrations >0.1 in 8% of samples, is an example of this type of herbicide. The average log-Kow of herbicides has decreased from the 1970s to the present, due to the strong trend towards the application of hydrophilic herbicides, such glyphosate. The need for increased monitoring of pesticides used in rice paddy farming is highlighted.

Preliminary study of clinical outcomes for single implant-retained mandibular overdentures.

This study evaluated marginal bone loss and prosthetic complications associated with single implant-retained mandibular overdentures (1-IODs) with locator attachments. The 1-IOD was placed in the mandibular midline by using a conventional loading protocol in 22 patients with an edentulous mandible. Marginal bone loss at the start of loading and 12 months postoperatively was assessed by radiographic and crestal bone evaluation. The crestal bone was defined as the distance between the customized abutment shoulder and the top of the bone, as indicated by probing. In addition, implant stability quotient and prosthetic complications were recorded. The cumulative implant survival rate was 95.5%. Median implant stability quotient remained greater than 80, and median radiographic bone loss was 0.56 mm. Crestal measurement showed a median crestal bone loss of 0.16, 0.43, 0.39, and 0.52 mm on the buccal, right, lingual, and left sides, respectively. Both radiographic and crestal bone loss values significantly differed between the start of implant loading and 12 months postoperatively (except on the buccal and lingual sides; P < 0.05). The need to replace the nylon insert was the most common complication. Conventional loading of a 1-IOD with a locator attachment resulted in a high survival rate, good implant stability, and acceptable marginal bone loss.

Masticatory function and bite force of mandibular single-implant overdentures and complete dentures: a randomized crossover control study.

PURPOSE: The study aimed to compare the mixing ability (MA), comminuting ability (CA), and maximum bite force (MBF) of single-implant overdentures (IODs) and clinically acceptable complete dentures (CDs) through a randomized crossover control trial. METHODS: New CDs were fabricated for 22 patients. One implant was inserted in the middle of the symphyseal region for each patient. The patients were randomly allocated into two groups: group IC received an IOD, whereas group CI received a CD, for 2 months; the treatments were interchanged for the next 2 months. The MA, CA, and MBF were evaluated with the old CDs, new CDs (at the end of CD treatment period), and IODs (at the end of IOD treatment period). RESULTS: The MA, CA, and MBF of the IODs were significantly higher than those of the old and new CDs (p < 0.01). New CDs only showed a significant improvement in MA (p < 0.05), while there were no significant differences in CA and MBF between the old and new CDs. CONCLUSIONS: Compared with the CD, IOD is more effective in restoring the MA, CA, and MBF of edentulous mandibles.

Is the default of 2 liters for daily per-capita water consumption appropriate? A nationwide survey reveals water intake in Japan.

Two liters per day is generally applied as the default drinking water intake rate for risk assessments, although evidence supporting this value is insufficient. This study aimed to reveal actual water intakes from tap water and other types of drinks, and to explore the relationships between these intakes. For this purpose, we conducted a nationwide Internet questionnaire survey. Tap water intake negatively correlated with bottled water and soft drink intakes, suggesting a mutually complementary relationship. We propose an index, potential Tap Water Intake (pTWI), calculated by adding soft drinks and bottled water to tap water intake. Mean per-capita tap water intake across the entire Japanese population was estimated at 1.28 L/d, whereas mean pTWI was estimated at 1.65 L/d. Two liters per day corresponds to the 88th percentile of tap water intake and to the 76th percentile of pTWI, and covers the intake of the majority of the population in Japan. This rate should continue being used as the default in the Japanese population, but the rate to cover the tap water intake of almost the entire population would be higher: it was >2.5 L/d.

The patient general satisfaction of mandibular single-implant overdentures and conventional complete dentures: Study protocol for a randomized crossover trial.

BACKGROUND: Mandibular overdentures retained by a single implant placed in the midline of edentulous mandible have been reported to be more comfortable and function better than complete dentures. Although single-implant overdentures are still more costly than conventional complete dentures, there are a few studies which investigated whether mandibular single-implant overdentures are superior to complete dentures when patient general satisfaction is compared. The aim of this study is to assess patient general satisfaction with mandibular single-implant overdentures and complete dentures. METHODS: This study is a randomized crossover trial to compare mandibular single-implant overdentures and complete dentures in edentulous individuals. Participant recruitment is ongoing at the time of this submission. Twenty-two participants will be recruited. New mandibular complete dentures will be fabricated. A single implant will be placed in the midline of the edentulous mandible. The mucosal surface of the complete denture around the implant will be relieved for 3 months. The participants will then be randomly allocated into 2 groups according to the order of the interventions; group 1 will receive single-implant overdentures first and will wear them for 2 months, followed by complete dentures for 2 months. Group 2 will receive the same treatments in a reverse order. After experiencing the 2 interventions, the participants will choose one of the mandibular prostheses, and yearly follow-up visits are planned for 5 years. The primary outcome of this trial is patient ratings of general satisfaction on 100 mm visual analog scales. Assessments of the prostheses and oral health-related quality of life will also be recorded as patient-reported outcomes. The secondary outcomes are cost and time for treatment. Masticatory efficiency and cognitive capacity will also be recorded. Furthermore, qualitative research will be performed to investigate the factors associated with success of these mandibular denture types. Clinical outcomes, such as implant survival rate, marginal bone loss, and prosthodontic complications, will also be recorded. DISCUSSION: The results of this randomized crossover trial will clarify whether mandibular single implants and overdentures for edentulous individuals provide better patient general satisfaction when compared to conventional complete dentures. TRIAL REGISTRATION: This clinical trial was registered at the University Hospital Medical Information Network (UMIN) Center (UMIN000017883).

Presence of the ß-triketone herbicide tefuryltrione in drinking water sources and its degradation product in drinking waters.

Triketone herbicides are becoming popular because of their herbicidal activity against sulfonylurea-resistant weeds. Among these herbicides, tefuryltrione (TFT) is the first registered herbicide for rice farming, and recently its distribution has grown dramatically. In this study, we developed analytical methods for TFT and its degradation product 2-chloro-4-methylsulfonyl-3-[(tetrahydrofuran-2-yl-methoxy) methyl] benzoic acid (CMTBA). TFT was found frequently in surface waters in rice production areas at concentrations as high as 1.9 µg/L. The maximum observed concentration was lower than but close to 2 µg/L, which is the Japanese reference concentration of ambient water quality for pesticides. However, TFT was not found in any drinking waters even though the source waters were purified by conventional coagulation and filtration processes; this was due to chlorination, which transforms TFT to CMTBA. The conversion rate of TFT to CMBA on chlorination was almost 100%, and CMTBA was stable in the presence of chlorine. Moreover, CMTBA was found in drinking waters sampled from household water taps at a similar concentration to that of TFT in the source water of the water purification plant. Although the acceptable daily intake and the reference concentration of CMTBA are unknown, the highest concentration in drinking water exceeded 0.1 µg/L, which is the maximum allowable concentration for any individual pesticide and its relevant metabolites in the European Union Drinking Directive.

Formation of 2,6-dichloro-1,4-benzoquinone from aromatic compounds after chlorination.

Halobenzoquinones are a group of disinfection byproducts formed by chlorination of certain substances in water. However, to date, the identities of halobenzoquinone precursors remain unknown. In this study, the formation of 2,6-dichloro-1,4-benzoquinone (DCBQ), a typical halobenzoquinone, from 31 aromatic compounds was investigated after 60 min of chlorination. DCBQ was formed from 21 compounds at molar formation yields ranging from 0.0008% to 4.9%. Phenol and chlorinated phenols served as DCBQ precursors, as reported previously. Notably, DCBQ was also formed from para-substituted phenolic compounds. Compounds with alkyl and carboxyl groups as para-substituents led to relatively higher molar formation yields of DCBQ. Moreover, p-quinone-4-chloroimide, 2,6-dichloroquinone-4-chloroimide (2,6-DCQC), and para-substituted aromatic amines (e.g., aniline and N-methyl aniline) served as DCBQ precursors upon chlorination. It was deduced that DCBQ was formed from the para-substituted aromatic amines via 3,5-dichloroquinone-4-chloroimide, a structural isomer of 2,6-DCQC. These results suggested that DCBQ was formed by chlorination of natural organic matter containing para-substituted phenolic species and para-substituted aromatic amines, despite the absence of phenol in water.

Hygienic practices and diarrheal illness among persons living in at-risk settings in Kabul, Afghanistan: a cross-sectional study.

BACKGROUND: Sustained civil and military conflict, resulting in large numbers of internally displaced persons (IDP), in combination with rapid urbanization has strained public health and sanitation within cities in Afghanistan. In order to examine the association between preventive sanitary behaviors and diarrhea within two high risk settings located within Kabul, Afghanistan, this study aimed to evaluate the prevalence of hygienic practices and diarrheal illness in an IDP camp and an urban slum. METHODS: In this cross sectional study, a convenience sample of residents of an IDP camp and an urban slum in Kabul, Afghanistan, was used. Participants were asked to describe their hygienic practices and interviewers independently documented household sanitation. The knowledge and attitudes about and practice of hygienic activities to prevent diarrhea were compared between the two settings. RESULTS: Two hundred participants, 100 from each setting, were enrolled. Knowledge, attitudes, and practices regarding hygienic activities to prevent diarrhea were greater among the slum dwellers than the IDP. Fewer than half of participants washed their hands with soap before eating or after eating: 31 % of slum dwellers washed before eating compared to 11 % of IDPs (P = 0.0050), and 25 % of slum dwellers washed after defecating compared to 4 % of IDPs (P = 0.0020). The IDPs were more likely to share a latrine (P = 0.0144) and less likely to disinfect their latrine than slum dwellers. Diarrhea in the household within the past 3 months was more common in the IDP camp (54 %) than the slum (20 %) (P = 0.0020). CONCLUSIONS: Even though certain sanitary and hygienic practices were more common among slum dwellers than IDPs, the lack of hygienic activities in both setting indicates that interventions to change behavior, like increasing the availability of soap and encouraging hand washing, are needed. Any initiative will have to be developed in the context of pervasive illiteracy among persons in both of these settings.

Determination of a N-Nitrosodimethylamine Precursor in Water Using Ultra-high Performance Liquid Chromatography-Tandem Mass Spectrometry.

1,1,5,5-Tetramethylcarbohydrazide (TMCH) is the main precursor of N-nitrosodimethylamine upon ozonation in the Yodo River basin, Japan. This study was performed to develop an analytical method for TMCH using solid-phase extraction with ultra-high performance liquid chromatography-tandem mass spectrometry. TMCH is hydrophilic and a tertiary amine derivative, so Oasis(®) MCX cartridges were used as solid-phase cartridges. The recoveries of TMCH in tap and river waters as well as secondary effluent from a sewage treatment plant ranged from 75 to 94%. The limit of quantification of TMCH was 4 ng L(-1). The source of TMCH in the Yodo River basin was found to be effluent from one sewage treatment plant. The concentrations were < 4 ng L(-1) in raw water from water purification plants in regions other than the Yodo River basin, indicating that TMCH was used specifically in the basin.

Identification of a new N-nitrosodimethylamine precursor in sewage containing industrial effluents.

N-Nitrosodimethylamine (NDMA), a potential human carcinogen, is known to be a disinfection byproduct of chloramination and ozonation. NDMA is formed during ozonation at water purification plants in the Yodo River basin, a major drinking water source in western Japan. An NDMA precursor, 1,1,5,5-tetramethylcarbohydrazide (TMCH) was identified in sewage containing industrial effluents via ultrahigh performance liquid chromatography-tandem mass spectrometry, and ultrahigh performance liquid chromatography-time-of-flight mass spectrometry, as well as nuclear magnetic resonance spectroscopy. The mean of the NDMA molar formation yield of TMCH upon ozonation in four water matrices was 140%. TMCH removal was low during biological treatment processes at a sewage treatment plant. The mean TMCH contribution to total NDMA precursors upon ozonation of the primary, secondary, and final effluents of the sewage treatment plant in January and February of 2014 was 43-72%, 51-72%, and 42-60%, respectively, while the contributions of 4,4'-hexamethylenebis(1,1-dimethylsemicarbazide) and 1,1,1',1'-tetramethyl-4,4'-(methylene-di-p-phenylene)disemicarbazide, two other known NDMA precursors, were limited to 0.6% and 6.9%, respectively. Thus, TMCH was identified as the primary precursor yielding NDMA upon ozonation in the Yodo River basin.

Formaldehyde formation from tertiary amine derivatives during chlorination.

In May 2012, formaldehyde (FA) precursor contamination in the Tone River Basin led to the suspension of water supply to approximately 360,000 homes, which affected approximately 870,000 people in the Tokyo Metropolitan Area. The discharge of industrial effluents containing hexamethylenetetramine (HMT), a tertiary amine and FA precursor, without proper treatment resulted in the formation of FA during chlorination at water purification plants. Tertiary amines are known to be the precursors of aldehydes upon chlorination. In this study, FA formation from 29 separate amine derivatives during chlorination was investigated to determine any other potential causes of this water quality accident. The FA formation yield also included FA formation by the autolysis of the target compounds as well as the chlorination of the autolysis products. The FA molar formation yield of HMT was the highest after 24h of chlorination (440%). Among the various tertiary amine derivatives containing N-methyl groups, tertiary amines and hydrazines were found to be strong FA precursors because the FA molar formation yields per N-methyl group ranged from 25% to 45% (with a mean of 38%) and from 35% to 45% (with a mean of 41%), respectively. Guanidines and sulfamides containing N-methyl groups were also FA precursors but they exhibited lower FA molar formation yields per N-methyl group. The FA molar formation yields of the remaining compounds were <4%. The FA formation yield of HMT was extremely high even on a per weight basis (95 wt.%). The FA weight formation yields of some tertiary amines and hydrazines were greater than 20 wt.%.

Occurrence of pepper mild mottle virus in drinking water sources in Japan.

Pepper mild mottle virus (PMMoV) is a plant virus that has been recently proposed as a potential indicator of human fecal contamination of environmental waters; however, information on its geographical occurrence in surface water is still limited. We aimed to determine the seasonal and geographic occurrence of PMMoV in drinking water sources all over Japan. Between July 2008 and February 2011, 184 source water samples were collected from 30 drinking water treatment plants (DWTPs); viruses from 1 to 2 liters of each sample were concentrated by using an electronegative membrane, followed by RNA extraction and reverse transcription. Using quantitative PCR, PMMoV was detected in 140 (76%) samples, with a concentration ranging from 2.03×10(3) to 2.90×10(6) copies/liter. At least one of the samples from 27 DWTPs (n=4 or 8) was positive for PMMoV; samples from 10 of these DWTPs were always contaminated. There was a significant difference in the occurrence of PMMoV among geographical regions but not a seasonal difference. PMMoV was frequently detected in samples that were negative for human enteric virus or Escherichia coli. A phylogenetic analysis based on the partial nucleotide sequences of the PMMoV coat protein gene in 12 water samples from 9 DWTPs indicated that there are genetically diverse PMMoV strains present in drinking water sources in Japan. To our knowledge, this is the first study to demonstrate the occurrence of PMMoV in environmental waters across wide geographical regions.

Contribution of tap water to chlorate and perchlorate intake: a market basket study.

The contributions of water to total levels of chlorate and perchlorate intake were determined using food and water samples from a market basket study from 10 locations in Japan between 2008 and 2009. Foods were categorized into 13 groups and analyzed along with tap water. The average total chlorate intake was 333 (min. 193-max. 486) µg/day for samples cooked with tap water. The contribution of tap water to total chlorate intake was as high as 47%-58%, although total chlorate intake was less than 32% of the tolerable daily intake, 1500 µg/day for body weight of 50 kg. For perchlorate, daily intake from water was 0.7 (0.1-4.4) µg/day, which is not high compared to the average total intake of 14 (2.5-84) µg/day, while the reference dose (RfD) is 35 µg/day and the provisional maximum tolerable daily intake (PMTDI) is 500 µg/day for body weight of 50 kg. The highest intake of perchlorate was 84 µg/day, where concentrations in foods were high, but not in water. The contribution of water to total perchlorate intake ranged from 0.5% to 22%, while the ratio of highest daily intake to RfD was 240% and that to PMTDI was 17%. Eight baby formulas were also tested--total chlorate and perchlorate intakes were 147 (42-332) µg/day and 1.11 (0.05-4.5) µg/day, respectively, for an ingestion volume of 1 L/day if prepared with tap water.

Removal of radioactive iodine and cesium in water purification processes after an explosion at a nuclear power plant due to the Great East Japan Earthquake.

The presence of radionuclides at five water purification plants was investigated after an explosion at a nuclear power plant hit by the Great East Japan Earthquake on 11 March 2011. Radioactive iodine (¹³¹I) and cesium (¹³4Cs and ¹³7Cs) were detected in raw water in Fukushima and neighboring prefectures. ¹³¹I was not removed by coagulation-flocculation-sedimentation. ¹³¹I was removed by granular activated carbon (GAC) and powdered activated carbon (PAC) at a level of about 30%-40%, although ¹³¹I was not removed in some cases. This was also confirmed by laboratory-scale experiments using PAC. The removal percentages of ¹³¹I in river and pond waters by 25 mg dry/L of PAC increased from 36% to 59% and from 41% to 48%, respectively, with chlorine dosing before PAC. ¹³4Cs and ¹³7Cs were effectively removed by coagulation at both a water purification plant and in laboratory-scale experiments when turbidity was relatively high. In contrast, ¹³4Cs and ¹³7Cs in pond water with low turbidity were not removed by coagulation. This was because ¹³4Cs and ¹³7Cs in river water were present mainly in particulate form, while in pond water they were present mainly as cesium ions (¹³4Cs+ and ¹³7Cs+). However, the removal of ¹³4Cs and ¹³7Cs in pond water by coagulation increased markedly when ¹³4Cs and ¹³7Cs were mixed with sediment 24 h before coagulation.

One-year weekly survey of noroviruses and enteric adenoviruses in the Tone River water in Tokyo metropolitan area, Japan.

To investigate the actual fluctuations in the concentrations of noroviruses (NoVs) GI and GII, and enteric adenoviruses (EAdVs) in river water and its relationship with the number of acute infectious gastroenteritis patients, one-year weekly quantitative monitoring of NoVs GI and GII and EAdVs was performed in the Tone River in Japan where the surface water is utilized for the main production of drinking water for the Tokyo Metropolitan Area from October 2009 to September 2010. Noroviruses GI and GII and EAdVs were detected in 28 (54%), 33 (63%), and 23 (44%) of the 52 samples (1 L each), respectively. The concentrations of NoVs GI and GII and EAdVs fluctuated strongly and were more abundant in winter and early spring. The concentration of NoVs GI was transiently greater than 10,000 copies/L. The number of acute infectious gastroenteritis patients in the upper river basin was highly correlated with all the viral concentrations, while general microbial indicator data such as turbidity and heterotrophic plate count were independent of viral concentration as suggested in previous studies. To the best of our knowledge, this is the first study that clearly shows the strong correlation of the number of gastroenteritis with virus contamination in lower river basin.

Development of a novel method for simultaneous concentration of viruses and protozoa from a single water sample.

A novel method, electronegative membrane-vortex (EMV) method, was developed for simultaneous concentration of viruses and protozoa from a single water sample. Viruses and protozoa in a water sample were mixed with a cation solution and adsorbed on an electronegative membrane. Concentrated virus and protozoa samples were obtained as supernatant and pellet fractions, respectively, by vigorous vortex mixing of the membrane and centrifugation of the eluted material. The highest recovery efficiencies of model microbes from river water and tap water by this EMV method were obtained using a mixed cellulose ester membrane with a pore size of 0.45 µm (Millipore) as the electronegative membrane and MgCl(2) as the cation solution. The recovery was 27.7-86.5% for poliovirus, 25.7-68.3% for coliphage Qß, 28.0-60.0% for Cryptosporidium oocysts, and 35.0-53.0% for Giardia cysts. The EMV method detected successfully indigenous viruses and protozoa in wastewater and river water samples from the Kofu basin, Japan, showing an overall positive rate of 100% (43/43) for human adenovirus, 79% (34/43) for norovirus GI, 65% (28/43) for norovirus GII, 23% (10/43) for Cryptosporidium oocysts, and 60% (26/43) for Giardia cysts. By direct DNA sequencing, a total of four genotypes (AI, AII, B, and G) of Giardia intestinalis were identified in the water samples, indicating that the river water was contaminated with feces from various mammals, including humans.