Sources and fate of Salmonella and fecal indicator bacteria in an urban creek

This research aimed to understand the sources and fate of Salmonella and fecal bacteria in urban surface waters. An urban creek (San Pedro Creek, California, USA) that had unusually high levels of Salmonella and fecal bacteria relative to other nearby waterbodies was chosen as a model field site. State of the art microbiological methods were used in concert with modeling to investigate Salmonella and fecal bacteria sources, and determine field-relevant dark inactivation and photoinactivation rates. Three along-creek surveys that spanned reaches adjacent to both urban and forested land covers were conducted to measure Salmonella, enterococci, Escherichia coli, and horse- and human-specific Bacteroidales. Salmonella were detected adjacent to and downstream of urban land cover, but not adjacent to forested land cover. No human or horse-specific Bacteroidales fecal markers were detected implicating other urban animal sources of bacteria. Two locations along the creek where Salmonella was consistently detected were sampled hourly for 25 hours and a mass-balance model was applied to determine field-relevant light and dark inactivation rates for Salmonella, enterococci, and E. coli. Sunlight inactivation did not appear to be important in modulating concentrations of Salmonella, but was important in modulating both enterococci and E. coli concentrations. Dark inactivation was important for all three organisms. This is the first study to quantitatively examine the fate of Salmonella within an urban surface water. Although the work is carried out at a single site, the methodologies are extendable to source tracking in other waterbodies. Additionally, the rate constants determined through the modeling will be useful for modeling these organisms in other surface waters, and represent useful benchmarks for comparison to laboratory-derived inactivation rates.     

Fecal indicator bacteria (FIB) levels during dry weather from Southern California reference streams

High levels of fecal indicator bacteria (FIB) in surface waters is a common problem in urban areas that often leads to impairment of beneficial uses such as swimming. Once impaired, common management and regulatory solutions include development of total maximum daily loads (TMDLs) and other water quality management plans. A critical element of these plans is establishment of a "reference" level of exceedances against which to assess management goals and TMDL compliance. The goal of this study was to provide information on indicator bacteria contributions from natural streams in undeveloped catchments throughout southern California during dry weather, non-storm conditions. To help establish a regional reference data set, bacteria levels [i.e. Escherichia coli (E. coli), enterococci and total coliforms] were measured from 15 unimpaired streams in 11 southern California watersheds weekly for one full year. Concentrations measured from reference areas were typically between one to two orders of magnitude lower than levels found in developed watersheds. Nearly 82% of the time, samples did not exceed daily and monthly bacterial indicator thresholds. E. coli had the lowest daily percent exceedance (1.5%). A total of 13.7% of enterococci exceeded daily thresholds. Indicator bacteria levels fluctuated seasonally with an average of 79% of both enterococci and total coliforms exceedances occurring during summer months (June to August). Temperature, at all sites, explained about one-half the variation in total coliforms density suggesting that stream temperatures regulated bacterial populations. Accounting for natural background levels will allow for management targets that are more reflective of the contributions from natural sources.     

Molecular detection of three gastroenteritis viruses in urban surface waters in Beijing and correlation with levels of fecal indicator bacteria

To assess the presence of three gastroenteritis viruses responsible for human acute gastroenteritis in surface water, a 1-year study was carried out in the city of Beijing, China. A total of 108 urban surface water samples were collected from nine collection sites which were defined with a global positioning system in rivers or lakes from September 2006 to August 2007. The water samples were subjected to virus concentration using an HA electronegative filter, followed by polymerase chain reaction (PCR) for rotavirus (RV) astrovirus (AV), and norovirus (NV). It showed that the number of viruses detected in water samples from different sites was variable, totaling 63 virus strains, with rotavirus (48.1%) verified as the most prevalent detected, followed by astrovirus (AV, 5.6%), and norovirus (NV, 4.6%). RV was also quantified by real-time PCR and the concentration of RV ranged from 0 to 18.27 genome copies·L(-1). And the distributions of RV in surface water were abundant in cold weather (from September to February) while less prevailing in warm weather (from March to August). The high detection rate of RV we encountered in this study provided convincing evidence that RV circulated at a certain frequency in the Beijing population. There was no statistically significant correlation between RV levels and both fecal coliform (R (2)?=?0.02) and Enterococcus faecalis (R (2)?=?0.02) densities. Our study suggests prolonged virus persistence in aquatic environments and emphasizes the enteric virus group as the most reliable for environmental monitoring.     

Assessing environmental impacts of treated wastewater through monitoring of fecal indicator bacteria and salinity in irrigated soils

To assess the potential for treated wastewater irrigation to impact levels of fecal indicator bacteria (FIB) and salinity in irrigated soils, levels of Escherichia coli, Enterococcus, and environmental covariates were measured in a treated wastewater holding pond (irrigation source water), water leaving the irrigation system, and in irrigated soils over 2 years in a municipal parkland in Arizona. Higher E. coli levels were measured in the pond in winter (56 CFU 100 mL⁻¹) than in summer (17 CFU 100 mL⁻¹); however, in the irrigation system, levels of FIB decreased from summer (26 CFU 100 mL⁻¹) to winter (4 CFU 100 mL⁻¹), possibly related to low winter water use and corresponding death of residual bacteria within the system. For over 2 years, no increase in FIB was found in irrigated soils, though highest E. coli levels (700 CFU g⁻¹ soil) were measured in deeper (20–25 cm) soils during summer. Measurements of water inputs vs. potential evapotranspiration indicate that irrigation levels may have been sufficient to generate bacterial percolation to deeper soil layers during summer. No overall increase in soil salinity resulting from treated wastewater irrigation was detected, but distinct seasonal peaks as high as 4 ds m⁻¹ occurred during both summers. The peaks significantly declined in winter when surface ET abated and more favorable water balances could be maintained. Monitoring of seasonal shifts in irrigation water quality and/or factors correlated with increases and decreases in FIB will aid in identification of any public health or environmental risks that could arise from the use of treated wastewater for irrigation.     

Tidally driven N, P, Fe and Mn exchanges in salt marsh sediments of Tagus estuary (SW Europe)

Short-sediment cores and flooding water were collected at 0, 5, 15, 25 and 50?min of tidal inundation in the two sites colonised by pure stands of Spartina maritima (low marsh) and Sarcocornia fruticosa (high marsh) from the Rosário salt marsh (Tagus estuary, SW Europe). Concentrations of NH (4) (+) , NO (3) (-) +?NO (2) (-) and HPO (4) (2-) , Fe and Mn were measured in tidal flooding water and pore water. Flooding water is enriched in nutrients, particularly ammonium due to local discharge of untreated urban effluents. Nevertheless, NH (4) (+) and NO (3) (-) +?NO (2) (-) concentrations in flooding waters at t?=?5?min (NH (4) (+) =?246?±?7?μM, NO (3) (-) +?NO (2) (-) =?138?±?1?μM for S. fruticosa and NH (4) (+) =?256?±?8?μM, NO (3) (-) +?NO (2) (-) =?138?±?1?μM for S. maritima) rose sharply at both vegetated sites. An increase was also registered for HPO (4) (2-) and total dissolved Fe although the subsequent decrease was smoother. Advective transport induced by the two daily pulses of inundation is several orders of magnitude higher than the diffusive fluxes during submerged periods. In addition, solutes are exported from the sediment with the inundation and imported in submerged periods. The exported amount of inorganic nitrogen during tidal inundation (export of 3,200?μmol?N?m(-2)?day(-1)to the water column), is not counterbalanced by the sink of -290?μmol?N?m(-2)?day(-1) occurred during the submerged period.     

An assessment of fecal indicator and other bacteria from an urbanized coastal lagoon in the City of Los Angeles, California, USA

A study was performed in Del Rey Lagoon, City of Los Angeles, to determine if the lagoon was as a source or sink for fecal indicator bacteria (FIB: total coliforms, Escherichia coli, enterococci) and to screen for the presence of other potentially pathogenic bacteria. The lagoon receives tidal flows from the adjacent Ballona Estuary whose water usually is contaminated with FIB originating from the highly urbanized Ballona Creek Watershed. During 16 sampling events from February 2008 through March 2009, replicate water samples (n?=?3) were collected 1 h prior to the high tide and 1 h prior to the following low tide. FIB concentrations were measured by the defined substrate method (IDEXX, Westbrook, Me) followed by culturing of bacterial isolates sampled from positive IDEXX Quanti-Tray wells and were identified using the Vitek 2 Compact (bioMérieux, Durham, NC). Mean concentrations of FIB often differed by an order of magnitude from flood to ebb flow conditions. The lagoon tended to act as a sink for total coliforms based on the ratio of mean flood to ebb densities (R _F/E) >1.0 during 56 % of the sampling events and during ebb flows, as a source for E. coli and enterococci (R _F/E <1.69 % of events). Approximately 54 species were identified from 277 isolates cultured from the IDEXX Quanti-Trays. Of these, 54 % were species known to include pathogenic strains that can be naturally occurring, introduced in runoff, or originated from other sources. Diversity and cluster analyses indicated a dynamic assemblage that changes in species composition with day-to-day fluctuations as well as tidal action. The concept of monitoring the lagoon and estuary as a sentinel habitat for pathogenic assemblages is discussed.     

Comparison of fecal coliform bacteria before and after wastewater treatment plant in the Izmir Bay (Eastern Aegean Sea)

The distribution of fecal coliforms was investigated and determined in Izmir Bay from 1996 to 2005. Izmir Bay severely was polluted from industrial and domestic discharges during decades. In early 2000, a wastewater treatment plant began to treat domestic and industrial wastes. This plant treats the wastes about 80% capacity after 2001. The sampling periods cover before and after treatment plant. Assessment method for determining the number of fecal coliform has evolved membrane filtrations. Maximum surface fecal coliform concentration was 4.9 × 10⁵ cfu 100 ml^???1 in 1996–2000 period. Following the opening treatment system, fecal coliform density decreased 2.1 × 10⁴ cfu 100 ml^???1 during 2001–2005. A continuous improvement can be sustained in the water quality if direct inflow of untreated wastewater is prevented.     

Abundance of sewage-pollution indicator and human pathogenic bacteria in a tropical estuarine complex

Studies on abundance and types of various pollution indicator bacterial populations from tropical estuaries are rare. This study was aimed to estimate current levels of pollution indicator as well as many groups of human pathogenic bacteria and their seasonal variations in different locations in Mandovi and Zuari Rivers in the central west coast of India. The sampling covered the estuarine and upstream regions of these rivers representing premonsoon (May 2005), monsoon (September 2006) and post-monsoon (November 2005). Both the abundance and types of autochthonous and allochthonous microbial populations in the near shore environments are affected by land drainages, domestic sewage outfalls and other discharges. The overall ranges (and their mean abundance; no. ml(-1)) of the monitored groups of bacteria were: total coliforms: 0-29,047 (3,134 ml(-1)); total streptococci: 3-14,597 (798); total vibrios: 13-42,275 (2,530); Escherichia coli: 0-1,333 (123); Vibrio cholerae: 0-3,012 (207); Salmonella spp: 0-1,646 (90); Streptococcus faecalis: 0-613 (88) and Aeromonas spp: 0-2,760 (205). In general, abundance of sewage pollution indicator bacteria such as total coliforms and total streptococci was lower than that reported from many other locations worldwide.     

Mercury uptake and allocation in Juncus maritimus: implications for phytoremediation and restoration of a mercury contaminated salt marsh

Juncus maritimus is the most abundant macrophyte in Laranjo bay, a Portuguese salt marsh heavily polluted by mercury (Hg). With the aim to elucidate the role of this species in the salt marsh Hg cycling and restoration, plants were harvested between March 2006 and January 2008 from four locations differing in Hg contamination. Metal uptake and distribution between plant organs were evaluated, biomass and Hg pools were also determined. Results showed that J. maritimus may influence the sediment pH and Eh, thus increasing the Hg available for uptake. Most (95-98%) of the absorbed Hg was retained belowground, phytostabilizing the metal and reducing the amount of Hg in the sediments. These results suggest that in salt marshes dominated by J. maritimus the approach could be phytostabilization, where these plants can be used to immobilize metals and store them belowground, reducing the pool of bioavailable Hg within contaminated marshes and acting as a sink rather than a source of contamination to the surrounding areas.     

Monitoring metal contamination levels and fecal pollution in clam (Tapes decussatus) collected from Izmir Bay (Turkey)

The aim of this study was to monitor the heavy metal contents and fecal pollution in Tapes decussatus (carpet shell clam) from Izmir Bay (Eastern Aegean). Bivalve mollusks were sampled on January, March, July, and October 2007 in the Izmir Bay. Izmir Bay is one of the great natural bays of the Mediterranean. Concentrations of heavy metals were determined in the clams from the different seasons. Fecal coliform densities were determined to evaluate the degree of water pollution and clams’ microbiological accumulation of the classical microbial pollution indicators. The concentration of heavy metals in T. decussatus from Izmir Bay were Hg 0.044–0.13; Cd 0.026–0.24; Pb 0.38–1.2; Cr 2.3–3.7; Cu 6.4–8.4; Zn 56.0–81.8, and Ni 8.1–9.6 μg/g (dry weight). The maximum values were generally obtained in July and March except Ni. This study found that the levels of heavy metals except Cr in T. decussatus were below Spanish and European Communities legislations for shellfish as food. Microbial pollution indicators (heterotrophic bacteria and fecal coliform) were measured in T. decussatus. Maximum heterotrophic bacteria and fecal coliforms were recorded in the winter while the lowest were detected in summer.     

Chironomid mouthpart deformities as indicator of environmental quality: a case study in Lake Trasimeno (Italy)

The aim of the present study was to monitor mouthpart deformities of Chironomus plumosus (Insecta-Diptera) in Lake Trasimeno (2000-2010) in relation with sediment contamination by heavy metals, which is one of the main causes of deformity induction. In Lake Trasimeno, concentrations of heavy metals in the investigated littoral zone were low, in comparison with those of the central area. By contrast, the incidence of deformities was much higher in the littoral station (2006-2009) than in the central area. In the littoral zone, the deformities progressively decreased and by 2010 reached values similar to those observed in the central area (2000-2002, 2010). This decrease was mainly due to the reduction of severe deformities, thus indicating an environmental quality recovery of this littoral sector. Chemical analysis revealed that the higher incidence of deformities in the littoral zone was not caused by heavy metal contamination, unless they may have contributed to a joint action with other toxicants. The present study on Lake Trasimeno provided additional evidence that chironomid mouthpart deformities can be used in biomonitoring programs to evaluate sediment contamination by toxicants. Since mouthpart deformities may also be induced by compounds not included in routine chemical analyses, they may better reflect sediment quality than chemical analysis alone.     

Using a relative health indicator (RHI) metric to estimate health risk reductions in drinking water

When a new drinking water regulation is being developed, the USEPA conducts a health risk reduction and cost analysis to, in part, estimate quantifiable and non-quantifiable cost and benefits of the various regulatory alternatives. Numerous methodologies are available for cumulative risk assessment ranging from primarily qualitative to primarily quantitative. This research developed a summary metric of relative cumulative health impacts resulting from drinking water, the relative health indicator (RHI). An intermediate level of quantification and modeling was chosen, one which retains the concept of an aggregated metric of public health impact and hence allows for comparisons to be made across “cups of water,” but avoids the need for development and use of complex models that are beyond the existing state of the science. Using the USEPA Six-Year Review data and available national occurrence surveys of drinking water contaminants, the metric is used to test risk reduction as it pertains to the implementation of the arsenic and uranium maximum contaminant levels and quantify “meaningful” risk reduction. Uranium represented the threshold risk reduction against which national non-compliance risk reduction was compared for arsenic, nitrate, and radium. Arsenic non-compliance is most significant and efforts focused on bringing those non-compliant utilities into compliance with the 10 μg/L maximum contaminant level would meet the threshold for meaningful risk reduction.     

Field evaluation of a passive sampler of polycyclic aromatic hydrocarbons (PAHs) in an urban atmosphere (Bologna, Italy)

A simple device consisting of a Petri dish containing cellulose paper soaked with paraffin oil (hereinafter defined "artificial leaf", AL) was deployed in a typical urban site and partitioning of a set of PAHs between the atmosphere and AL was investigated. Gas-phase PAHs rapidly equilibrate with AL, thus rendering it a promising cost-effective tool for spatial and temporal trends studies of air quality.     

Concentrations of heavy metals in urban soils of Talcahuano (Chile): a preliminary study

Concentrations of Cd, Cr, Ni, Pb, and Zn in the top-(0–10 cm) and sub-surface (10–20 cm) soils of the Talcahuano urban area were measured. The main soil properties (organic matter, CaCO₃, pH, particle sizes) were determined for a network of representative sampling sites. The mean Cr, Ni, Pb, and Zn contents in the urban topsoil samples from Talcahuano (37.8, 22.6, 35.2, 333 mg kg⁻¹, respectively) were compared with mean concentrations for other cities around the world. The results revealed higher concentrations of heavy metals in topsoil samples than in sub-surface samples. The samples from IS1, IS2, and IS3, located in the Talcahuano industrial park, had higher Cr, Ni, Pb, and Zn contents than did samples from the other sites. This was probably due to local pollution by industrial (metallurgical) dust, although other diffuse pollution throughout the entire port region (shipyards, metallurgy, the dismantling of old ships), and contributions from the wind from adjacent industrial, storage, and vessel areas clearly played a role. Heavy metals were lowest in the sample taken on school grounds (SG).     

Enteromorpha flexuosa (Wulfen) J. Agardh (Chlorophyta: Ulvales)--evaluation as an indicator of heavy metal contamination in a tropical estuary

The use of bioindicators for contaminant monitoring ispopular in all sectors of the environment but quite oftenbioindicators are utilised without rigorous evaluation oftheir viability as an indicator. We report field andlaboratory investigations into the value of a commonlyfound macroalga, Enteromorpha flexuosa (Wulfen) J.Agardh (Chlorophyta: Ulvales) as an indicator of copper,zinc and lead contamination in a tropical estuary inFiji. In the laboratory, metal content of E.flexuosa after 60 days of growth in seawater containingincreasing concentrations of the metals showed almostperfect correlation with metal concentrations in waterfor all three metals, and concentration factors obtainedwere generally higher than values reported for otherspecies of Enteromorpha. Performance in the fieldwas evaluated by a one-year monitoring of metals in E. flexuosa, water and sediments from a contaminatedestuary. Metal concentrations in water were always belowdetection limits and field concentration factors couldnot be determined but the concentration of lead in E. flexuosa showed a high correlation with the leadcontent of sediments. Lack of such correlation forcopper and zinc in the field suggests that otherenvironmental factors besides metal load in the physicalenvironment could be controlling the bioaccumulation ofthese two metals. Whilst demonstrating E. flexuosato be a viable bioindicator for lead, these results alsohighlight the need for proper assessment before anorganism is considered for environmental monitoring.     

Study of urban atmospheric pollution in Navarre (Northern Spain)

An ambient air quality study was undertaken in two cities (Pamplona and Alsasua) of the Province of Navarre in northern Spain from July 2001 to June 2004. The data were obtained from two urban monitoring sites. At both monitoring sites, ambient levels of ozone, NO_x, and SO₂ were measured. Simultaneously with levels of PM₁₀ measured at Alsasua (using a laser particle counter), PM₁₀ levels were also determined at Pamplona (using a beta attenuation monitor). Mean annual PM₁₀ concentrations in Pamplona and Alsasua reached 30 and 28 μg m⁻³, respectively. These concentrations are typical for urban background sites in Northern Spain. By using meteorological information and back trajectories, it was found that the number of exceedances of the daily PM₁₀ limit as well as the PM₁₀ temporal variation was highly influenced by air masses from North Africa. Although North African transport was observed on only 9% of the days, it contributed the highest observed PM₁₀ levels. Transport from the Atlantic Ocean was observed on 68% of the days; transport from Europe on 13%; low transport and local influences on 7%; and transport from the Mediterranean region on 3% of the days. The mean O₃ concentrations were 45 and 55 μg m⁻³ in Pamplona and Alsasua, respectively, which were above the values reported for the main Spanish cities. The mean NO and NO₂ levels were very similar in both sites (12 and 26 μg m⁻³, respectively). Mean SO₂ levels were 8 μg m⁻³ in Pamplona and 5 μg m⁻³ in Alsasua. Hourly levels of PM₁₀, NO and NO₂ showed similar variations with the typically two coincident maximums during traffic rush hours demonstrating a major anthropogenic origin of PM₁₀, in spite of the sporadic dust outbreaks.     

Linear alkylbenzenesulfonates (LAS) of an urban stream in Korea

Profiles of alkyl homologues and isomers of LAS were monitored for an urban stream polluted with municipal wastewaters in Korea. Alkylchains of the stream LAS were shorter than commercial standards and higher I/E ratios were associated with lower LAS concentrations. These suggested a partial biodegradation of LAS in the stream. Higher LAS concentrations were observed in the upper stream. LAS levels were at their lowest during summer probably due to high precipitation and faster biodegradation rates. LAS contributed to about 29% of MBAS and could be used to roughly estimate BOD concentration of the stream.     

水中粪大肠菌群快速检测方法-固定底物酶底物法与多管发酵法的比较

目的在于比较固定底物酶底物法与多管发酵法用于水中粪大肠菌群(耐热大肠菌群)的检测,使用科立得TM(Colilert(R))试刺和传统方法检测地表水、水源水及污水水样,比较固定底物酶底物法与多管发酵法用于水中粪大肠菌群(耐热大肠菌群)检测结果的一致性.结果表明,固定底物酶底物法与多管发酵法用于水中粪大肠菌群(耐热大肠菌群)检测结果具有一致性,固定底物酶底物法可以用作评价水质微生物污染的标准方法.     

Stormwater metal loading to a well-mixed/stratified estuary (Sydney Estuary, Australia) and management implications

Stormwater modelling indicated an average annual discharge from Sydney estuary catchment of 215,300 mL and loadings of 0.8, 0.5, 1.7, 3.2, 1.1, 3.6 and 17.7 tonnes for As, Cd, Cr, Cu, Ni, Pb and Zn, respectively. Priority for remediation should be given to creeks with high-metal loads in the upper and central estuary, as well as discharging to the western shores of Middle Harbour. Managerial strategies need to target dissolved and particulate metal phases to ensure effective remediation. The proportion of metals discharged under low- (<5 mm rainfall/day), medium- (>5 to <50 mm/day) and high-flow conditions (>50 mm/day) was approximately 10%, 60% and 30% of total loading, respectively. Under high-flow conditions the estuary becomes stratified and most metals are exported to the sea, whereas metals discharged during low-flow may be remediated by infiltration. Effective remediation will depend on the extent to which ‘first-flush’ metals associated with medium-flow conditions can be remediated.