A Traditional Analysis of the First Flush Effect for Nutrients in Stormwater Runoff from Two Small Urban Catchments

Nonpoint stormwater runoff remains a major threat to surface water quality in the USA. More effective stormwater control measures can be designed by understanding patterns in pollutant export with respect to the runoff hydrograph. In particular, nutrient concentrations in urban stormwater can cause deleterious effects in sensitive watersheds in the Southeast and Mid-Atlantic USA. A year-long study captured stormwater samples from 36 storm events at two catchments (one primarily impermeable and the other substantially wooded) and analyzed for total suspended solids and various nutrient species. Using these data, the first flush effect (the assumption that the initial portion of a rainfall-runoff event is more polluted than the later portions) was evaluated based on several published methods and definitions. Based on an analysis of multiple methodologies, the ranking of first flush strength among the pollutants was total suspended solids (TSS) > ammonia (NH₃) > total Kjeldahl nitrogen > NO₂-NO₃ > total phosphorus > orthophosphate (O-PO₄). Nitrogen species generally displayed a stronger first flush than phosphorus species, with O-PO₄ showing the weakest first flush effect. Various relationships ° climate, land use, and the first flush strength were also explored. Of the rainfall characteristics analyzed, total rainfall and runoff volume each inversely affected the first flush strength of TSS on the more impervious catchment. Although orthophosphate did not have a strong first flush effect, the relative first flush strength for O-PO₄ increased with increasing rainfall or runoff. Land use did not influence the first flush strength of the pollutants. On average, most pollutants exhibited a slight first flush effect, but substantial pollutant loading still occurred in the latter portion of the storm??s total runoff volume. Thus, treating the majority of a storm??s total pollutant load requires capturing a commensurate fraction of runoff volume.     

Evidence for the Accumulation and Steady-State Persistence of E. coli in Subtropical Drainage Basin Sediments

While the presence of fecal indicator bacteria such as Escherichia coli in urban stormwater has been widely documented, their occurrence and persistence in sediments are not as well understood. Recent investigations suggest that E. coli can accumulate in drainage basin sediments and act as a fecal bacterial reservoir within a watershed. We investigate the prevalence of E. coli populations in a tidal creek stormwater catchment and examine their interaction with overlying stormwater under wet and dry weather conditions. Two rain events are sampled more intensively with samples collected prior to, during, and after rainfall to profile bacteria in each matrix throughout a storm. Results of profile sampling and estimates of sediment resuspension provide evidence for E. coli accumulation during dry conditions and entrainment in overlying waters during storm conditions. Profile results suggest the occurrence of steady-state E. coli populations in drainage basin sediments.     

Transport Of Fecal Bacteria From Poultry Litter and Cattle Manures Applied to Pastureland

Land applications of manure from confined animal systems and direct deposit by grazing animals are both major sources of bacteria in streams. An understanding of the overland transport mechanisms from land applied waste is needed to improve design of best management practices (BMPs) and modeling of nonpoint source (NPS) pollution. Plots were established on pasturelands receiving phosphorus-based livestock waste applications to measure the concentrations of Escherichia coli (E. coli), fecal coliform (FC), and Enterococcus present in overland flow at the edge of the field. The flow-weighted bacteria concentrations were highest in runoff samples from the plots treated with cowpies (1.37×10⁵ colony forming units (cfu)/100 ml of E. coli) followed by liquid dairy manure (1.84×10⁴ cfu/100 ml of E. coli) and turkey litter (1.29×10⁴ cfu/100 ml of E. coli). The temporal distribution of fecal bacterial concentrations appeared to be dependent upon both the animal waste treatment and the indicator species, with peak concentrations occurring either at the beginning of the runoff event or during peak flow rates. BMPs could be selected to reduce peak flows or first flush effects depending upon the litter or manure applied to the land. The commercial Biolog System was used to identify the dominant species of Enterococcus present in the cowpie source manure (Enterococcus mundtii 55%) and in the runoff collected from the transport plots treated with cowpies (Enterococcus faecalis 37%). The identification of predominant species of Enterococcus that are associated with specific sources of fecal pollution could greatly assist with identifying the origins of NPS pollution.     

Identification of an Assemblage of Indicator Organisms to Assess Timing and Source of Bacterial Contamination in Groundwater

Bacterial contamination of drinking water wells is a commonproblem in many rural areas. Some of this contamination may berelated to manure spreading or housing of livestock; another source is on-site septic systems. Current indicator organisms are able to detect the presence of fecal contamination, but where there may be more than one potential source of fecal material, the current indicators are unable to ascertain the origin. This laboratory investigation was undertaken to determine the longevity and reliability of a selected suite of indicator organisms. Total coliform, fecal coliform, fecal streptococci and Clostridium perfringens were monitoredin a simulated contaminated groundwater environment for 6 months. All four indicator organisms were present at the end of6 months. The number of fecal streptococi bacteria decreased most noticeably, allowing assessment of relative age of contamination. C. perfringens was found to be a reliableindicator of contamination from animal manure. Fecal material from 28 different animals and three septic systems were assessed for the presence of the indicator organisms. Totalcoliform, fecal coliform and fecal streptococci were present in the fecal material of all animals tested including reptiles.C. perfringens was detected in feces from all but two of the animals assessed. Using an assemblage of indicator organisms provides more information regarding source and timingof contamination than just testing for total coliform and fecalcoliform bacteria.     

Effect of Anaerobic Digestion and Application Method on the Presence and Survivability of <Emphasis Type="Italic">E. coli</Emphasis> and Fecal Coliforms in Dairy Waste Applied to Soil

Animal wastes are commonly used in a sustainable manner to fertilize crops. However, manures contain numerous pathogenic bacteria that can impact animal and human health. Treatment of animal waste by anaerobic digestion has the potential to reduce pathogen loading to land. This study was conducted to determine the fate of bacteria applied in raw and anaerobically digested dairy slurries that were broadcast and subsurface applied in a field of forage grasses. Digested slurry had significantly fewer indicator bacteria, Escherichia coli and fecal coliform at time of application. Anaerobic digestion did not increase the survivability of indicator bacteria. Waste treatment and application method did not affect the rate of bacteria die-off. There were fewer E. coli and fecal coliform at the end of each trial in the soils that received digested slurry. Anaerobic digestion of dairy waste has the potential to reduce pathogenic bacteria loading to cropland.     

Relationship Between Fecal Indicators in Sediment and Recreational Waters in a Danish Estuary

The European Union has introduced a new bathing water directive where future classification of recreational waters will be based on the microbial parameters Escherichia coli, and intestinal enterococci. Introduction of enterococci as a new quality parameter may pose a challenge in some areas because relatively less is known about these organisms compared to E. coli. In the present study, the relative abundance of intestinal enterococci, E. coli, and ten fecal sterol and stanol biomarkers were investigated in water and sediment at two estuarine beach sites affected by fecal pollution. In the bathing water, enterococci were relatively more abundant at low E. coli concentrations. In the sediment, enterococci were generally more abundant than E. coli with surface concentrations between 1.0?×?10² and 4.5?×?10³ CFU cm^?3. Enterococci populations were relatively similar in water and sediment, and were phenotypically different from that of nearby pollution sources. The putative human specific genetic marker esp in Enterococcus faecium was not detected in water or sediment samples despite occasional inputs of human waste from storm water overflows. Sterol and stanol profiles suggested a direct link between water and sediment pollution profiles on days with wind conditions that facilitated resuspension. Sediment resuspension may occur at wind speeds exceeding 6–8 m s^?1, and could contribute significantly to enterococci concentrations in the overlying water. The study emphasized that recontamination of the water column due to wind induced resuspension should be considered when evaluating indicator levels and microbial hazards in estuarine recreational waters.     

Assessing Storm Water Detention Systems Treating Road Runoff with an Artificial Neural Network Predicting Fecal Indicator Organisms

This paper examines whether multiple regression analysis and neural network models can be applied successfully for the indirect prediction of the runoff treatment performance with water quality indicator variables in an experimental storm water detention system rig. Five biologically mature experimental storm water detention systems with different designs treating concentrated gully pot liquor (spiked with dog droppings) were assessed. The systems were located on The King’s Buildings campus at The University of Edinburgh and were monitored for a period of 18 months. Multiple regression analyses indicated a relatively successful prediction of the biochemical oxygen demand and total suspended solids for most systems, but due to a relatively weak correlation between the predictors and both microbial indicators, multiple regression analyses were not applied for the prediction of intestinal enterococci and total coliform colony-forming units. However, artificial neural network models predicted microbial counts relatively well for most detention systems.     

Development of Regression-Based Models to Predict Fecal Bacteria Numbers at Select Sites within the Illinois River Watershed, Arkansas and Oklahoma, USA

The Illinois River Watershed is a multi-facet basin with ecological and economic importance to its local stakeholders in northwest Arkansas and northeast Oklahoma, USA. The numbers, transport and sources of fecal bacteria in streams was identified as a research priority of the USDA NRI Water and Watershed Program in 2006, and the objective of this study was to evaluate the relation between fecal bacteria and other measured physicochemical parameters in water samples collected from selected sites throughout the Illinois River Watershed. An existing database (i.e., National Water Information Systems, NWIS) from the US Geological Survey (USGS) was used in this project. The data obtained includes discharge, pH, temperature, dissolved oxygen, Escherichia coli (E. coli), fecal coliform, and fecal streptococci among several other physic-chemical parameters. A synthetic model, based on multi-regression analysis, was developed to predict fecal bacteria numbers at these selected sites based on available USGS NWIS data, and the multiple regressions were significant at almost every site for all three bacteria groups. However, the physicochemical parameters used in the equations were very different across sites and fecal bacteria groups, suggesting that the development of such predictive models is site and bacteria group specific even within one watershed.     

Fecal coliform dispersal by rain splash on slopes

The movement of fecal pathogens from land to surface and ground water are of great interest because of the public health implications. Non-structural best management practices that control the timing, volume, and placement of animal manures are commonly used to limit opportunities for fecal pathogens to enter water bodies. Increased infiltration capacity, water and waste diversions, and vegetated filter strips are used to control fecal pathogen movement in surface runoff. Fecal pathogens transported by rain splash could conceivably bypass physical barriers. The relationship between slope angle and the transport of fecal coliform bacteria by rain splash was studied. It was hypothesized that there would be a significant down slope transport of fecal coliform bacteria by raindrops falling on a bare soil surface inoculated with fecal coliform bacteria. Slopes from 0° to 40.8° were studied. The mean splash distance for fecal coliforms was less than 50 mm in all directions at 0° slope and more than 500 mm in the downslope direction on a 40.8° slope. Maximum splash distances ranged from about 400 mm on the horizontal surface to more than 1900 mm in the downslope direction on the 40.8° slope. Sequential downhill movement of fecal coliform (FC) bacteria by repeated rain splash could transport FC directly to water bodies or areas of saturation excess where they will become entrained in overland runoff. Further studies on raindrop and rainfall characteristics, as well as surface cover and soil characteristics, will be necessary to more fully understand the mechanisms of FC transport on sloping land by rain splash.     

Escherichia coli and Enterococci Attachment to Particles in Runoff from Highly and Sparsely Vegetated Grassland

Limited data on microbial partitioning between the freely suspended and particulate attached phases during transport along overland flow pathways have resulted in high uncertainty in bacterial fate and transport models and the application of these models to watershed management plans. The objectives of this study were to examine differences in attachment between E. coli and enterococci in runoff from plots with highly and sparsely vegetated grassland; investigate relations between flow regime, total suspended solids, and E. coli and enterococci attachment; and identify the particle size categories to which the attached cells were associated. Two rainfall simulations were conducted on large field plots 3 m wide by 18.3 m long with highly and both highly and sparsely vegetated covers and treated with standard cowpats. Results from the first experiment representing pasture with highly vegetated cover indicate that the majority of E. coli and enterococci are transported from the fresh manure source in the unattached state with only 4.8% of E. coli and 13% of enterococci associated with particles. The second experiment which compared partitioning in runoff from both highly and sparsely vegetated covers found lower bacterial attachment rates: the average E. coli percent attached was 0.06% from plots with highly vegetated cover and 2.8% from plots with sparsely vegetated cover while the corresponding values for enterococci were 0.98% and 1.23%, respectively. The findings from this study provide the first set of data on bacterial partitioning in overland flow from large field plots, and results may be helpful for parameterizing water quality models and designing conservation practices.     

Fecal coliform and E. coli estimates,tip of the iceberg

Pure cultures of E. coli, Klebsiella and Enterobacter, obtained from hospital patients and from natural waters were tested for their growth patterns by spread plate and membrane filtration procedures at the following temperatures; 35°, 41.5°, 43°, 44.5°, and 35°C for 4 h followed by 18 h at 44.5°C. Results indicated that 44.5°C incubation produces the lowest population estimate and that the application of the membrane filtration technique also reduced the potential population. Three water samples collected during June, August and November were tested for fecal coliform and E. coli populations, with 11 different media (broth and agar) and incubation temperatures of 35°, 41.5°, 43°, 44.5°, and 35°C for 4 h followed by 18 h at 44.5°C. During the study, isolates were collected from all positive MPN tubes at each temperature and from each MF medium-temperature regime, 24 to 50 isolates were collected. From the isolate data corrected coliform (oxidase negative), fecal coliform and E. coli population estimates were made. A sample of feces was diluted in lake water and maintained at 20°C for 56 days. Samples were collected at various times and tested for fecal coliform densities using five media and the same temperature regime as for the lake water samples. Data from these studies indicate that, depending on the age of the population being measured, the temperature of the water sample, and the temperature-media-procedure combination used, fecal coliform and E. coli population estimate techniques measure from 5 to 100% of the potential population.     

The use of clams as bioindicator of fecal pollution in seawater

The coastal waters of Kuwait are widely used for bathing during the long summer season. In order to assess the water quality along the beaches, a new approach was developed. It involves the use of clam, Circenita callipyga, as a bioindicator for seawater pollution by fecal coliform bacteria (FC), antibotic resistant fecal coliform (ABR-FC) and Salmonella spp. These organisms were detected in clam and water samples and the efficiency of clam in concentrating Salmonella was confirmed. The number of FC and ABR-FC in clam and water samples were compared and a higher number was detected in clams than in water. Five isolates of Salmonella from clams were also multidrug resistant. The data suggests that clam can be used as a bioindicator of seawater pollution and is preferable to direct testing of water. The resistance to antibiotics in E. coli isolated from water and clams collected at the same time and site was of similar pattern and was determined by R-plasmid.     

Dynamics of Clay Particles in Non-vegetated Stormwater Biofilters

Stormwater biofilters manage quantity and quality of urban stormwater runoff. Particulate solids from natural and anthropogenic sources accumulate on paved surfaces and eventually reach receiving waters. Retention of suspended solids in stormwater management systems ensures the quality of stormwater runoff to water resources. Stormwater biofilters are similar in most of design parameters to sand filters employed in water treatment systems. The understanding and design of stormwater biofilters are often based on generic models of sand filters. Unlike water treatment sand filters, which are continuously fed, stormwater biofilters operate intermittently with spontaneously alternating wetting and drying cycles. This results in dynamic pollutant removal pattern that employs different mechanisms during and across rainfall events. As such, pilot scale biofilter columns fabricated with a layer of organic material were operated. Removal of suspended solids was very dynamic, where impact of age of filter, antecedent dry days, and inflow quality varied during and across events. Flush of retained solids and filter material occurred during the stabilisation period during each event while very high removal percentages (more than 90%) were observed after stabilisation, during an event. Clogging was not observed due to re-entrainment, re-distribution, and flush of retained solids during intermittent wetting and drying cycles.     

Evaluation of Greenwaste Mulch to Control Runoff Quality from Landfill Sites During Frequent Storms

This paper describes a preliminary evaluation of two types of greenwaste (fresh and aged) used as a mulch layer to control runoff from disturbed landfill areas. Fresh greenwaste refers to woody and herbaceous garden waste that has been recently collected, chopped and shredded. Aged greenwaste is greenwaste which has been stockpiled for 18 months. We used rainfall simulator tests to investigate two aspects: (1) the performance of greenwaste mulch in reducing runoff during designed storm events with a high frequency of occurrence and (2) the release of pollutants via runoff as total suspended solids (TSS) and total organic carbon (TOC) during rain. Rainfall of <5-year average recurrence interval (ARI) was generally applied, consistent with stormwater compliance requirements for many Australian landfills. TOC released from fresh greenwaste material was higher in concentration than from aged greenwaste. However, when used as a 10-cm-deep mulch layer, fresh greenwaste was able to completely prevent runoff, even when tested under rainfalls of up to 50-year ARI duration. An equivalent mulch layer of aged greenwaste was also effective in reducing runoff volume and TSS concentration compared with the bare soil during a 3.5-year ARI rainfall, but mean TOC concentration was higher. Based on these preliminary results, fresh greenwaste mulching of bare soils is an attractive option to control runoff and erosion from areas subject to intermittent landfill operations and worthy of further investigations.     

Indicator bacteria concentrations as affected by hydrologic variables in the Apalachicola river,Florida

Concentrations of fecal coliform and fecal Streptococcus bacteria were monitored in the Apalachicola River, Florida, at various river stages. Bacteria transported by the river may eventually be assimilated by estuarine filter feeders, including shellfish. Sources along the river contributed to relatively high coliform and coliform: Streptococcus ratios at a few sites upstream, but there was a general decreasing trend in coliform numbers in a downstream direction. The data suggested that coliform densities depend not only on discharge, but also on factors such as whether the river stage is rising or falling, whether the flood is in an early or late phase, and the volume of the current peak relative to earlier peaks. A regression model indicated that 53 % of fecal coliform variability could be accounted for by river discharge and 32% could be accounted for by other hydrologic characteristics of the flood.     

Efficiency and Flow Regime of a Highway Stormwater Detention Pond in Washington, USA

Wet detention ponds are a preferable alternative in treating stormwater runoff. Literature suggests that a detention pond’s efficiency in removing principal pollutants of concern, TSS and metals, is highly variable and is affected by a complex array of factors including its geographic location. The objective of this paper was to investigate the TSS and metal removal efficiency of a highway stormwater detention pond in Spokane, Washington along with its flow regime. Pond influent and effluent data for TSS and metal were collected for approximately two years. TSS removal by the pond was found to be 68.1–99.4% with an average of 83.9%. Average metal removal efficiency was 54.7–64.6% which is 72.5–86.9% of the TSS removal. The pond’s flow regime was found to vary with its changing surface topography, a result of sedimentation of suspended solids.     

Effect of heavy metals on growth population of a fecal coliform bacterium Escherichia coli in aquatic environment

The data on the effects of the concentrations (0.5, l, 2, 5 mg L^?1) of the heavy metals, Hg, As, Pb, Cu, Cd, and Cr on changes in growth population of a fecal coliform bacterium Escherichia coli (in term of number of E. coli per 100 mL water) showed a gradual decline in growth population of the fecal coliform bacterium with the increase of exposure time, as well as concentrations of the metals over control data. The effects were markedly recorded with the treatment of 5 mg L^?1. In general, the harmful effects of the metals on growth population of E. coli were found by the treatments in the order: Cd>Ph>Cu>As>Hg>Cr.     

Manure as a Source of Antibiotic-Resistant Escherichia coli and Enterococci: a Case Study of a Wisconsin, USA Family Dairy Farm

The spread of antibiotic-resistant bacteria in the environment is raising serious public health concerns, and manure is being increasingly recognized as a major source of antibiotic-resistant bacteria. In this research, we isolated Escherichia coli and enterococci from manure produced in a Wisconsin, USA family dairy farm to determine their resistance to six representative antibiotics. The average densities for E. coli and enterococci were 6.37(±4.38)?×?10⁷ colony formation units (CFU)?g^?1 and 1.60(±1.57)?×?10⁴ CFU g^?1, respectively. The E. coli isolates were found to be resistant to cephalothin, ampicillin, tetracycline, and erythromycin. In addition to these four antibiotics, the Enterococcus isolates were also resistant to gentamicin and ciprofloxacin. Additionally, we examined the survival and growth of E. coli and enterococci in dairy manure over a period of ~3 days. While the densities of enterococci remained stable over the study period, the concentrations of E. coli on average increased by 1.5 log10 units. Further tests of the bacterial antibiotic resistance over time showed no significant changes in the prevalence of antibiotic resistance. This result indicated that slightly aged manure could represent a larger source of antibiotic-resistant E. coli than fresh manure and the accumulation of antibiotic-resistant E. coli and enterococci in the agricultural fields must be accounted for in the modeling of the spread of antibiotic-resistant bacteria in the environment.     

Influence of pH on the elimination of fecal coliform bacteria in waste stabilization ponds

From the results of in vitro studies carried out on wastewater from a stabilization pond it can be concluded that pH values close to 9, as a single factor, do not play any essential role in the die-off of fecal coliform bacteria. The percentage of elmination that occurs in pond water inoculated with 1.1×10¹⁰ cells of E. coli mL^?1 where the pH is maintained at 8.2 (original pH) is 99.997%, a much greater reduction than that observed (94.1%) in distilled water inoculated with the same concentration of E. coli and where pH is increased up to 9.     

Mineral and Anthropogenic Indicator Inorganics in Urban Stormwater and Snowmelt Runoff: Sources and Mobility Patterns

Inorganic chemicals in urban stormwater and snowmelt runoff originate from catchment geology and anthropogenic activities. The occurrence, partitioning and mobility of six minerals and six trace metal (TM) indicators of anthropogenic activities were studied in stormwater, snowmelt and baseflow in four urban catchments, and the sampling of inorganics was supplemented by measurements of electrical conductivity (EC), pH and total suspended solids (TSSs). Minerals occurred at concentrations several orders of magnitude higher (1–10² mg/L) than those of TMs (10^?2–10² μg/L) and reflected the composition of local groundwater seeping into sewers. Concentrations of Ca, K, Mg and Na were enhanced by baseflow contributions and followed closely the electrical conductivity. Al and Fe minerals occurred in insoluble forms, and their pollutographs were similar to those of TMs, whose concentrations mimicked, to some extent, the flux of TSS. The TMs with the highest and lowest particulate fractions were Cr&Pb and Cu&Zn, respectively. The concentrations of total TMs in snowmelt were two to four times higher than those in stormwater, and both sources likely exceeded some of the stormwater effluent limits (for Cd, Cu and Zn) proposed in Sweden. Where such concentrations depended on water hardness, the risk of toxicity might be reduced by elevated hardness of the monitored snowmelt and stormwater. Recognizing the good ecological status of the study area receiving water, Lake Storsjön, some protection against polluted runoff and snowmelt may be needed and could be achieved by implementing stormwater management measures controlling TSS and TMs.