Toxicological effects of herbicides on the fish environment Part 1
Abstract has not been submitted
Water and Sewage Works↗
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Toxicological effects of herbicides on the fish environment Part 2
Abstract has not been submitted
Water and Sewage Works↗
Ground-water and drainage problems in the Whitney terrace area, Boise, Idaho
Ground-water levels in the Whitney terrace area, after many years of rise owing to downward percolation of water from irrigated land, became nearly stabilized by 1935. Strong seasonal water-level fluctuations of 8 to 10 feet, however, are common in the Boise Valley. In recent years, the Whitney terrace has been changing rapidly from a farming to an urban community. The 3,200-acre area now has about 15,000 inhabitants and the land area is about 35-percent occupied by urban developments. Population trends indicate that urban expansion will continue. Coincident with the change from rural to urban conditions on the Whitney terrace, the patterns of water use were drastically altered. The amount of irrigated land has decreased but the amount of ground-water recharge from irrigation and yard water may have increased. Liquid sewage effluent disposed in the ground also has increased the yearly volume of recharge. The estimated average yearly amount of recharge from all sources now is about 2.4 acre-feet per acre. Full urban development of the area may increase recharge from all sources to about 3.3 acre-feet per acre. Ground-water and drainage problems can be relieved by reducing excessive recharge to the ground-water reservoir. Reduction can be accomplished by economical use of water by individuals, establishment of a water-tight public sewage system to transport all sewage to a central plant outside of the area, and by drainage works. These measures would cause a net decline of ground-water levels in the area. They can be undertaken separately or collectively.
Idaho↗
Pharmaceuticals in on-site sewage effluent and ground water, Western Montana
Human use of pharmaceuticals results in the excretion and disposal of compounds that become part of municipal and domestic waste streams. On-site waste water disposal and leaking city sewer systems can provide avenues for the migration of effluent to the underlying aquifers. This research assessed the occurrence and persistence of 22 target pharmaceuticals in septic tank effluent and two shallow, coarse-grained aquifers in western Montana. Twelve compounds (acetaminophen, caffeine, codeine, carbamazepine, cotinine, erythromycin-18, nicotine, paraxanthine, ranitidine, sulfamethoxazole, trimethoprim, and warfarin) were detected in a high school septic tank effluent. Three of the 12 compounds, carbamazepine, sulfamethoxazole, and nicotine, were detected in the underlying sand and gravel aquifer after effluent percolation through a 2.0-m thick sand vadose zone. Sampling of a second sand, gravel, and cobble dominated unconfined aquifer, partially overlain by septic systems and a city sewer system, revealed the presence of caffeine, carbamazepine, cotinine, nicotine, and trimethoprim. The presence of carbamazepine and sulfamethoxazole in these aquifers appears to correlate with local usage based on a reported monthly prescription volume. This work highlights the need for expanding geochemical investigations of sewage waste impacted ground water systems to include sampling for selected pharmaceuticals. ?? 2007 National Ground Water Association.
Ground Water↗
A water-budget approach to estimating potential groundwater recharge from two domestic sewage disposal fields in eastern Bernalillo County, New Mexico, 2011-12
Eastern Bernalillo County, New Mexico, is a historically rural area that in recent years has experienced an increase in population and in the construction of new housing units, most of which are not connected to a centralized wastewater treatment system. Increasing water use has raised concerns about the effect of development on the available groundwater resources in the area. During 2011–12, the U.S. Geological Survey, in cooperation with Bernalillo County Public Works Natural Resource Services, used a water-budget approach to quantify the amount of potential groundwater recharge occurring from the domestic sewage (effluent) dosed to the sewage disposal field at two locations—sites A and B—in eastern Bernalillo County, N. Mex. The amount of effluent that is potentially available for groundwater recharge was determined as the mean daily volume of effluent dosed to the disposal field in excess of the mean daily volume of effluent loss from evapotranspiration from the disposal field. During this study, the disposal fields at sites A and B received a measured volume of effluent from two-person domestic residences equipped with an onsite low-pressure dosing system. A combined evapotranspiration measurement and modeling technique was used to estimate the amount of evapotranspirative loss from the disposal field and from the surrounding terrain. A portable hemispherical flux chamber was used to measure evapotranspiration at fixed locations on the disposal fields and on the surrounding terrain at sites A and B. Data from hemispherical flux chamber measurements were used to calibrate a Penman-Monteith modeled evapotranspiration rate on the disposal field and on the surrounding terrain at site A from January 1, 2011, to December 31, 2011, and from January 1, 2012, to December 31, 2012, and at site B from January 1, 2011, to December 31, 2011. Micrometeorological and soil data from instrumentation on the disposal fields and on the surrounding terrain at sites A and B were used as input data into the Penman-Monteith equation. The mean potential recharge from disposal field effluent during 2011–12 at sites A and B was 63 percent of the volume of effluent dosed to the disposal field.
New Mexico↗
Nutrient loadings to streams of the continental United States from municipal and industrial effluent?
Data from the United States Environmental Protection Agency Permit Compliance System national database were used to calculate annual total nitrogen (TN) and total phosphorus (TP) loads to surface waters from municipal and industrial facilities in six major regions of the United States for 1992, 1997, and 2002. Concentration and effluent flow data were examined for approximately 118,250 facilities in 45 states and the District of Columbia. Inconsistent and incomplete discharge locations, effluent flows, and effluent nutrient concentrations limited the use of these data for calculating nutrient loads. More concentrations were reported for major facilities, those discharging more than 1 million gallons per day, than for minor facilities, and more concentrations were reported for TP than for TN. Analytical methods to check and improve the quality of the Permit Compliance System data were used. Annual loads were calculated using "typical pollutant concentrations" to supplement missing concentrations based on the type and size of facilities. Annual nutrient loads for over 26,600 facilities were calculated for at least one of the three years. Sewage systems represented 74% of all TN loads and 58% of all TP loads. This work represents an initial set of data to develop a comprehensive and consistent national database of point-source nutrient loads. These loads can be used to inform a wide range of water-quality management, watershed modeling, and research efforts at multiple scales.
Journal of the American Water Resources Associatio↗
Water Quality in the Mahoning River and Selected Tributaries in Youngstown, Ohio
The lower reaches of the Mahoning River in Youngstown, Ohio, have been characterized by the Ohio Environmental Protection Agency (OEPA) as historically having poor water quality. Most wastewater-treatment plants (WWTPs) in the watershed did not provide secondary sewage treatment until the late 1980s. By the late 1990s, the Mahoning River still received sewer-overflow discharges from 101 locations within the city of Youngstown, Ohio. The Mahoning River in Youngstown and Mill Creek, a principal tributary to the Mahoning River in Youngstown, have not met biotic index criteria since the earliest published assessment by OEPA in 1980. Youngstown and the OEPA are working together toward the goal of meeting water-quality standards in the Mahoning River. The U.S. Geological Survey collected information to help both parties assess water quality in the area of Youngstown and to estimate bacteria and inorganic nitrogen contributions from sewer-overflow discharges to the Mahoning River. Two monitoring networks were established in the lower Mahoning River: the first to evaluate hydrology and microbiological and chemical water quality and the second to assess indices of fish and aquatic-macroinvertebrate-community health. Water samples and water-quality data were collected from May through October 1999 and 2000 to evaluate where, when, and for how long water quality was affected by sewer-overflow discharges. Water samples were collected during dry- and wet-weather flow, and biotic indices were assessed during the first year (1999). The second year of sample collection (2000) was directed toward evaluating changes in water quality during wet-weather flow, and specifically toward assessing the effect of sewer-overflow discharges on water quality in the monitoring network. Water-quality standards for Escherichia coli ( E. coli ) concentration and draft criteria for nitrate plus nitrite and total phosphorus were the regulations most commonly exceeded in the Mahoning River and Mill Creek sampling networks. E. coli concentrations increased during wet-weather flow and remained higher than dry-weather concentrations for 48 hours after peak flow. E. coli concentration criteria were more commonly exceeded during wet-weather flow than during dry-weather flow. Exceedances of nutrient-concentration criteria were not substantially more common during wet-weather flow. The fish and aquatic macroinvertebrate network included Mill Creek and its tributaries but did not include the main stem of the Mahoning River. Persistent exceedances of chemical water-quality standards in Mill Creek and the presence of nutrient concentrations in excess of draft criteria may have contributed to biotic index scores that on only one occasion met State criteria throughout the fish and aquatic macroinvertebrate sampling network. Monitored tributary streams did not contribute concentrations of E. coli , nitrate plus nitrite, or total phosphorus to the Mahoning River and Mill Creek that were higher than main-stem concentrations, but monitored WWTP and sewer-overflow discharges did contribute. Twenty-four hour load estimates of sewer-overflow discharge contributions during wet-weather flow indicated that sewer-overflow discharges contributed large loads of bacteria and inorganic nitrogen to the Mahoning River relative to the instream load. The sewer-overflow loads appeared to move as a slug of highly enriched water that passed through Youngstown on the rising limb of the storm hydrograph. The median estimated sewer-overflow load contribution of bacteria was greater than the estimated instream load by a factor of five or more; however, the median estimated sewer-overflow load of inorganic nitrogen was less than half of the estimated instream load. Sewer-overflow discharges contributed loads of E. coli and nutrients to the Mahoning River and Mill Creek at a point where the streams already did not meet State water-quality regulations. Improvement of water quality of the Mahoning River, Mill Creek, and tributaries at Youngstown would be facilitated by reducing loads from sewer-overflow discharges within Youngstown, by identifying and reducing other sources of E. coli and nutrients within Young-stown, and by reducing discharges of E. coli , nitrate plus nitrite, and total phosphorus to the Mahoning River and Mill Creek upstream from Youngstown.
Water-Resources Investigations Report↗
Analysis of multiple enteric viral targets as sewage markers in coral reefs
Water and coral mucus samples were collected from throughout the Florida Keys National Marine Sanctuary and the Dry Tortugas for three years and were analyzed for human enteric viruses (enteroviruses, noroviruses, hepatitis A virus and adenoviruses) as conservative markers of human sewage using molecular methods. Of the 100 coral and water samples collected, 40 contained genetic material from one or more human enteric viruses. DNA-based adenoviruses were detected widely, in 37.8% of samples and at 91% of stations, including ‘pristine’ reefs in the Dry Tortugas; however, the detection rate was ⩽12% for the RNA-based enteroviruses and noroviruses (hepatitis A virus was never detected). The disparity between the prevalence of RNA- and DNA-based viruses suggests the need for additional work to determine the utility of adenovirus as marker of human sewage.
Florida↗
In-situ sediment oxygen demand rates in Hammonton Creek, Hammonton, New Jersey, and Crosswicks Creek, near New Egypt, New Jersey, August-October 2009
Sediment oxygen demand rates were measured in Hammonton Creek, Hammonton, New Jersey, and Crosswicks Creek, near New Egypt, New Jersey, during August through October 2009. These rates were measured as part of an ongoing water-quality monitoring program being conducted in cooperation with the New Jersey Department of Environmental Protection. Oxygen depletion rates were measured using in-situ test chambers and a non-consumptive optical electrode sensing technique for measuring dissolved oxygen concentrations. Sediment oxygen demand rates were calculated on the basis of these field measured oxygen depletion rates and the temperature of the stream water at each site. Hammonton Creek originates at an impoundment, then flows through pine forest and agricultural fields, and receives discharge from a sewage-treatment plant. The streambed is predominantly sand and fine gravel with isolated pockets of organic-rich detritus. Sediment oxygen demand rates were calculated at four sites on Hammonton Creek and were found to range from -0.3 to -5.1 grams per square meter per day (g/m 2 /d), adjusted to 20 degrees Celsius. When deployed in pairs, the chambers produced similar values, indicating that the method was working as expected and yielding reproducible results. At one site where the chamber was deployed for more than 12 hours, dissolved oxygen was consumed linearly over the entire test period. Crosswicks Creek originates in a marshy woodland area and then flows through woodlots and pastures. The streambed is predominantly silt and clay with some bedrock exposures. Oxygen depletion rates were measured at three sites within the main channel of the creek, and the calculated sediment oxygen demand rates ranged from -0.33 to -2.5 g/m 2 /d, adjusted to 20 degrees Celsius. At one of these sites sediment oxygen demand was measured in both a center channel flowing area of a pond in the stream and in a stagnant non-flowing area along the shore of the pond where organic-rich bottom sediments had accumulated and lower dissolved oxygen concentration conditions existed in the water column. Dissolved oxygen concentrations in the center channel test chamber showed a constant slow decrease over the entire test period. Oxygen consumption in the test chamber at the near-shore location began rapidly and then slowed over time as oxygen became depleted in the chamber. Depending on the portion of the near-shore dissolved oxygen depletion curve used, calculated sediment oxygen demand rates ranged from as low as -0.03 g/m 2 /d to as high as -10 g/m 2 /d. The wide range of sediment oxygen demand rates indicates that care must be taken when extrapolating sediment oxygen demand rates between stream sites that have different bottom sediment types and different flow regimes.
New Jersey↗
Quantification of human-associated fecal indicators reveal sewage from urban watersheds as a source of pollution to Lake Michigan
Sewage contamination of urban waterways from sewer overflows and failing infrastructure is a major environmental and public health concern. Fecal coliforms (FC) are commonly employed as fecal indicator bacteria, but do not distinguish between human and non-human sources of fecal contamination. Human Bacteroides and human Lachnospiraceae , two genetic markers for human-associated indicator bacteria, were used to identify sewage signals in two urban rivers and the estuary that drains to Lake Michigan. Grab samples were collected from the rivers throughout 2012 and 2013 and hourly samples were collected in the estuary across the hydrograph during summer 2013. Human Bacteroides and human Lachnospiraceae were highly correlated with each other in river samples (Pearson’s r = 0.86), with average concentrations at most sites elevated during wet weather. These human indicators were found during baseflow, indicating that sewage contamination is chronic in these waterways. FC are used for determining total maximum daily loads (TMDLs) in management plans; however, FC concentrations alone failed to prioritize river reaches with potential health risks. While 84% of samples with >1000 CFU/100 ml FC had sewage contamination, 52% of samples with moderate (200–1000 CFU/100 ml) and 46% of samples with low (<200 CFU/100 ml) FC levels also had evidence of human sewage. Load calculations in the in the Milwaukee estuary revealed storm-driven sewage contamination varied greatly among events and was highest during an event with a short duration of intense rain. This work demonstrates urban areas have unrecognized sewage inputs that may not be adequately prioritized for remediation by the TMDL process. Further analysis using these approaches could determine relationships between land use, storm characteristics, and other factors that drive sewage contamination in urban waterways.
Wisconsin↗
Factors affecting Escherichia coli concentrations at Lake Erie public bathing beaches
The environmental and water-quality factors that affect concentrations of Escherichia coli (E. coli) in water and sediment were investigated at three public bathing beachesEdgewater Park, Villa Angela, and Sims Parkin the Cleveland, Ohio metropolitan area. This study was done to aid in the determination of safe recreational use and to help water- resource managers assess more quickly and accurately the degradation of recreational water quality. Water and lake-bottom sediments were collected and ancillary environmental data were compiled for 41 days from May through September 1997. Water samples were analyzed for E. coli concentrations, suspended sediment concentrations, and turbidity. Lake- bottom sediment samples from the beach area were analyzed for E. coli concentrations and percent dry weight. Concentrations of E. coli were higher and more variable at Sims Park than at Villa Angela or Edgewater Park; concentrations were lowest at Edgewater Park. Time-series plots showed that short-term storage (less than one week) of E. coli in lake-bottom sediments may have occurred, although no evidence for long-term storage was found during the sampling period. E. coli concentrations in water were found to increase with increasing wave height, but the resuspension of E. coli from lake-bottom sediments by wave action could not be adequately assessed; higherwave heights were often associated with the discharge of sewage containing E. coli during or after a rainfall and wastewater-treatment plant overflow. Multiple linear regression (MLR) was used to develop models to predict recreational water quality at the in water. The related variables included turbidity, antecedent rainfall, antecedent weighted rainfall, volumes of wastewater-treatment plant overflows and metered outfalls (composed of storm-water runoff and combined-sewer overflows), a resuspension index, and wave heights. For the beaches in this study, wind speed, wind direction, water temperature, and the prswimmers were not included in the model because they were shown to be statistically unrelated to E. coli concentrations. From the several models developed, one model was chosen that accounted for 58 percent of the variability in E. coli concentrations. The chosen MLR model contained weighted categorical rainfall, beach-specific turbidity, wave height, and terms to correct for the different magnitudes of E. coli concentrations among the three beaches. For 1997, the MLR model predicted the recreational water quality as well as, and in some cases better than, antecedent E. coli concentrations (the current method). The MLR model improved the sensitivity of the prediction and the percentage of correct predictions over the current method; however, the MLR model predictions still erred to a similar degree as the current method with regard to false negatives. A false negative would allow swimming when, in fact, the bathing water standard was exceeded. More work needs to be done to validate the MLR model with data collected during other recreational seasons, especially during a season with a greater frequency and intensity of summer rains. Studies could focus on adding to the MLR model other environmental and water-quality variables that improve the predictive ability of the model. These variables might include concentrations of E. coli in deeper sediments outside the bathing area, the direction of lake currents, site-specific-rainfall amounts, time-of-day information on overflows and metered outfalls, concentrations of E. coli in treated wastewater-treatment plant effluents, and occurrences of sewage-line breaks. Rapid biological or chemical methods for determination of recreational water quality could also be used as variables in model refinements. Possible methods include the use of experimental rapid assay methods for determination of E. coli concentrations or other fecal indicators and the use of chemical tracers for fecal contamination, such as coprostanol (a degradation
Water-Resources Investigations Report↗
How do we determine when the beaches are safe for swimming?
The use of Lake Erie and other public waters for swimming is a valuable recreational resource for the people of Ohio and elsewhere in the United States. Water-resource managers and the scientific community have recognized the need for rapid methods to determine the quality of these recreational waters to adequately protect public health. Fecal-indicator bacteria, such as Escherichia coli ( E. coli ) and fecal coliforms, are used to determine the risk of contracting waterborne disease from fecal-contaminated recreational waters. Fecal-indicator bacteria are not necessarily pathogens ( disease-causing organisms), but their presence can indicate the possible presence of pathogens. Although improvements to existing sewage treatment systems are continuously being made in many areas, fecal contamination is still a possibility. Therefore, findings from carefully designed monitoring programs are needed to inform the public on the risk of swimming in fecal-contaminated waters. Current methods to assess the concentrations of fecal indicators-that is, the number of bacteria in a certain volume of water-take at least 24 hours to complete. Due to the long time frame, some scientists have suggested using other water-quality or environmental surrogates (substitutes) to determine these concentrations. The U.S. Geological Survey (USGS) is working to address this concern in a study conducted at three Lake Erie beaches in the Cleveland, Ohio, area. The study has shown that turbidity (the amount of light scattered or absorbed by suspended materials in a water sample), rainfall, and wave height could be used in a statistical model to predict E. coli concentrations.
Ohio↗
Use of an airborne Fraunhofer line discriminator for the detection of solar stimulated luminescence
Luminescence is the property of some materials to emit light when excited by external stimuli such as ultraviolet or visible light or by chemical or mechanical action. The Fraunhofer line discriminator (FLO) is an airborne electro-optical device which operates as a non-imaging radiometer and permits detection of solar stimulated luminescence several orders of magnitude below the intensity detectable with the human eye. A prototype FLO, used in 1969 to monitor the dynamic of water currents in the San Francisco area, was than 5 parts per Airborne tests o a redesigned FLO, featuring an order of magnitude improvement in sensitivity, permitted measurement of differences in the luminescence of trees containing geochemically anomalous concentrations of Colorado) and molybdenum (near Gardnerville, Nevada) trees growing in background areas nearby. In the tests near Denver, luminescence-contrast between stressed and non-stressed trees tended to be greater during periods when cloud cover was 10 percent or less; in most cases, contrast insignificant when cloud cover exceeded 10 percent. In other airborne test the FLO distinguished luminescing phosphate rock and gypsum from sands one and siltstone near Pine Mountain, California; dispersal of oil in a natural seep from uncontaminated sea water in the Santa Barbara Channel; cattle feed lot and municiple sewage effluents near Denver; and paper and phosphate processing effluents in eastern and central Florida. Procedures employing a laboratory fluorescence spectrometer permit prediction of the detectivity with an FLO prior to monitoring an airborne test. Luminescence spectra of the material are corrected for wavelength variation in spectrometer source, detector sensitivity, and solar illumination. By comparing these results with the luminescence of a rhodamine WT dye standard, the luminescence .of the material may be expressed in terms of rhodamine dye equivalency at the wavelength of several Fraunhofer lines. The FLO detectivity may be assessed at each Fraunhofer line, and the optimum line for field observation of the material may be selected. Future work will include the integration of the FLO with a line scan imaging system in order to assess the contribution of two-dimensional spatial resolution to the interpretability and usefulness of luminescence data. It should also include 1) investigation of luminescence polarization of some materials, particularly metal stressed plants, 2) an assessment of the use of pulsed lasers to stimulate phosphorescence decay time in the nanosecond and microsecond ranges; and 3) a study to determine the feasibility of conducting an FLO experiment from the Space Shuttle or other spacecraft.
Open-File Report↗
Numerical simulation of vertical ground-water flux of the Rio Grande from ground-water temperature profiles, central New Mexico
An important gap in the understanding of the hydrology of the Middle Rio Grande Basin, central New Mexico, is the rate at which water from the Rio Grande recharges the Santa Fe Group aquifer system. Several methodologies-including use of the Glover-Balmer equation, flood pulses, and channel permeameters- have been applied to this problem in the Middle Rio Grande Basin. In the work presented here, ground-water temperature profiles and ground-water levels beneath the Rio Grande were measured and numerically simulated at four sites. The direction and rate of vertical ground-water flux between the river and underlying aquifer was simulated and the effective vertical hydraulic conductivity of the sediments underlying the river was estimated through model calibration. Seven sets of nested piezometers were installed during July and August 1996 at four sites along the Rio Grande in the Albuquerque area, though only four of the piezometer nests were simulated. In downstream order, these four sites are (1) the Bernalillo site, upstream from the New Mexico State Highway 44 bridge in Bernalillo (piezometer nest BRN02); (2) the Corrales site, upstream from the Rio Rancho sewage treatment plant in Rio Rancho (COR01); (3) the Paseo del Norte site, upstream from the Paseo del Norte bridge in Albuquerque (PDN01); and (4) the Rio Bravo site, upstream from the Rio Bravo bridge in Albuquerque (RBR01). All piezometers were completed in the inner-valley alluvium of the Santa Fe Group aquifer system. Ground-water levels and temperatures were measured in the four piezometer nests a total of seven times in the 24-month period from September 1996 through August 1998. The flux between the surface- and ground-water systems at each of the field sites was quantified by one-dimensional numerical simulation of the water and heat exchange in the subsurface using the heat and water transport model VS2DH. Model calibration was aided by the use of PEST, a model-independent computer program that uses nonlinear parameter estimation. Mean vertical hydraulic conductivities were estimated by model calibration and range from 1.5x10 -5 to 5.8x10 -6 meters per second (m/s). Mean simulated vertical ground-water flux for the BRN02 piezometer nest is 3.30x10 -7 m/s; for the COR01 piezometer nest is 3.58x10 -7 m/s; for the PDN01 piezometer nest is 4.22x10 -7 m/s; and for the RBR01 piezometer nest is 2.05x10 -7 m/s. Comparison of the simulated vertical fluxes and vertical hydraulic conductivities derived from this study with values from other studies in the Middle Rio Grande Basin indicate agreement between 1 and 3.5 orders of magnitude for hydraulic conductivity and within 1 order of magnitude for vertical flux.
New Mexico↗
Nutrient pollution of coastal rivers, bays, and seas
Over the past 40 years, antipollution laws have greatly reduced discharges of toxic substances into our coastal waters. This effort, however, has focused largely on point-source pollution of industrial and municipal effluent. No comparable effort has been made to restrict the input of nitrogen (N) from municipal effluent, nor to control the flows of N and phosphorus (P) that enter waterways from dispersed or nonpoint sources such as agricultural and urban runoff or as airborne pollutants. As a result, inputs of nonpoint pollutants, particularly N, have increased dramatically. Nonpoint pollution from N and P now represents the largest pollution problem facing the vital coastal waters of the United States. Nutrient pollution is the common thread that links an array of problems along the nations coastline, including eutrophication, harmful algal blooms, dead zones, fish kills, some shellfish poisonings, loss of seagrass and kelp beds, some coral reef destruction, and even some marine mammal and seabird deaths. More than 60 percent of our coastal rivers and bays in every coastal state of the continental United States are moderately to severely degraded by nutrient pollution. This degradation is particularly severe in the mid Atlantic states, in the southeast, and in the Gulf of Mexico. A recent report from the National Research Council entitled Clean Coastal Waters: Understanding and Reduc- ing the Effects of Nutrient Pollution concludes that: Nutrient over-enrichment of coastal ecosystems generally triggers ecological changes that decrease the biologi- cal diversity of bays and estuaries. While moderate N enrichment of some coastal waters may increase fish production, over-enrichment generally degrades the marine food web that supports commercially valuable fish. The marked increase in nutrient pollution of coastal waters has been accompanied by an increase in harmful algal blooms, and in at least some cases, pollution has triggered these blooms. High nutrient levels and the changes they cause in water quality and the makeup of the algal community are detrimental to the health of coral reefs and the diversity of animal life supported by seagrass and kelp communi- ties. Research during the past decade confirms that N is the chief culprit in eutrophication and other impacts of nutrient over-enrichment in temperate coastal waters, while P is most problematic in eutrophication of freshwa- ter lakes. Human conversion of atmospheric N into biologically useable forms, principally synthetic inorganic fertilizers, now matches the natural rate of biological N fixation from all the land surfaces of the earth. Both agriculture and the burning of fossil fuels contribute significantly to nonpoint flows of N to coastal waters, either as direct runoff or airborne pollutants. N from animal wastes that leaks directly to surface waters or is volatilized to the atmosphere as ammonia may be the largest single source of N that moves from agricultural operations into coastal waters. The National Research Council report recommended that, as a minimum goal, the nation should work to reverse nutrient should be taken to assure that the 40 percent of coastal areas now ranked as healthy do not develop symptoms of nutrient pollution in 10 percent of its degraded coastal systems by 2010 and 25 percent of them by 2020. Also, action should be taken to assure that the 40 percent of coastal areas now ranked as healthy do not develop symptoms of nutrient pollution. Meeting these goals will require an array of strategies and approaches tailored to specific regions and coastal ecosystems. There is an urgent need for development and testing of techniques that can reliably pinpoint the sources of N pollutants to an estuary. For some coastal systems, N removal during treatment of human sewage may be sufficient to reverse nutrient pollution. For most coastal systems, however, the solutions will be more complex and may involve controls on N compounds emitted during fossil fuel combustion as well as incentives to reduce over-fertilization of agricul- tural fields and nutrient pollution from animal wastes in livestock feedlot operations.
Alabama, California, Connecticut, Delaware, Florid↗
Two risk assessments: Evaluating the use of indicator HF183 Bacteroides versus pathogen measurements for modelling recreational illness risks in an urban watershed
The purpose of this study was to evaluate the performance of HF183 Bacteroides for estimating pathogen exposures during recreational water activities. We compared the use of Bacteroides -based exposure assessment to exposure assessment that relied on pathogen measurements. We considered two types of recreational water sites: those impacted by combined sewer overflows (CSOs) and those not impacted by CSOs. Samples from CSO-impacted and non-CSO-impacted urban creeks were analysed by quantitative polymerase chain reaction (qPCR) for HF183 Bacteroides and eight human gastrointestinal pathogens. Exposure assessment was conducted two ways for each type of site (CSO-impacted vs. non-CSO impacted): 1) by estimating pathogen concentrations from HF183 Bacteroides concentrations using published ratios of HF183 and pathogens in sewage and 2) by estimating pathogen concentrations from qPCR measurements. QMRA (quantitative microbial risk assessment) was then conducted for swimming, wading, and fishing exposures. Overall, mean risk estimates varied from 0.27 to 53 illnesses per 1,000 recreators depending on exposure assessment, site, activity, and norovirus dose-response model. HF183-based exposure assessment identified CSO-impacted sites as higher risk, and the recommended HF183 risk-based threshold of 525 genomic copies per 100 mL was generally protective of public health at the CSO-impacted sites but was not as protective at the non-CSO-impacted sites. In the context of our urban watershed, HF183-based exposure assessment over- and under-estimated risk relative to exposure assessment based on pathogen measurements and the etiology of predicted pathogen-specific illnesses differed significantly. Across all sites, the HF183 model overestimated risk for norovirus, adenovirus, and Campylobacter jejuni , and it underestimated risk for E. coli and Cryptosporidium . To our knowledge, this study is the first to directly compare health risk estimates using HF183 and empirical pathogen measurements from the same waterways. Our work highlights the importance of site-specific hazard identification and exposure assessment to decide whether HF183 is applicable for monitoring risk.
Pennsylvania↗
Two-dimensional advective transport in ground-water flow parameter estimation
Nonlinear regression is useful in ground-water flow parameter estimation, but problems of parameter insensitivity and correlation often exist given commonly available hydraulic-head and head-dependent flow (for example, stream and lake gain or loss) observations. To address this problem, advective-transport observations are added to the ground-water flow, parameter-estimation model MODFLOWP using particle-tracking methods. The resulting model is used to investigate the importance of advective-transport observations relative to head-dependent flow observations when either or both are used in conjunction with hydraulic-head observations in a simulation of the sewage-discharge plume at Otis Air Force Base, Cape Cod, Massachusetts, USA. The analysis procedure for evaluating the probable effect of new observations on the regression results consists of two steps: (1) parameter sensitivities and correlations calculated at initial parameter values are used to assess the model parameterization and expected relative contributions of different types of observations to the regression; and (2) optimal parameter values are estimated by nonlinear regression and evaluated. In the Cape Cod parameter-estimation model, advective-transport observations did not significantly increase the overall parameter sensitivity; however: (1) inclusion of advective-transport observations decreased parameter correlation enough for more unique parameter values to be estimated by the regression; (2) realistic uncertainties in advective-transport observations had a small effect on parameter estimates relative to the precision with which the parameters were estimated; and (3) the regression results and sensitivity analysis provided insight into the dynamics of the ground-water flow system, especially the importance of accurate boundary conditions. In this work, advective-transport observations improved the calibration of the model and the estimation of ground-water flow parameters, and use of regression and related techniques produced significant insight into the physical system.
Massachusetts↗
Identifying sources of contaminants in urban stormwater and evaluation of their removal efficacy across a continuum of urban best management practices
Precipitation events in urban areas often result in stormwater runoff containing a diverse array of chemical contaminants. Although many traditional contaminants, such as nutrients, heavy metals, and polycyclic aromatic hydrocarbons have been studied extensively, only recently has evidence emerged showing that trace organic compounds (TrOCs), including pharmaceuticals, personal care products and pesticides are frequently found in stormwater runoff. As there is little existing information about the sources of TrOCs in urban stormwater or their removal efficacy across a range of stormwater treatment options, we conducted a study to address these knowledge gaps and to characterize the potential contribution of TrOCs to groundwater resources from stormwater infiltration practices, based on several synoptic measurements. The current study allowed us to enhance an existing effort to assess TrOC presence and toxicity in stormwater runoff and treatment pond outflow by addressing questions related to TrOC sources to stormwater and TrOC transport to groundwaters. Analysis of eDNA confirms multiple sources of TrOCs to stormwater including human sewage, dog waste, and feces from waterfowl. It is likely that the presence of some TrOCs detected in stormwater are the result of direct, untreated sewage inputs to stormwater from either human (i.e., leaking sewer infrastructure) or pet waste (washed from sidewalks into storm drains). The seasonal detection of avian eDNA is noteworthy as it highlights seasonality and patterns of migration patterns as contributing factors to stormwater contamination. In contrast to human and pet waste, which likely enters stormwater ponds via the stormwater conveyance system, avian feces may enter ponds either through stormwater runoff or through direct inputs by waterfowl stopping-over temporarily at stormwater ponds. Stormwater ponds had little effect in reducing TrOCs as determined by comparative inflow and outflow analysis. Our results also indicate that overall few TrOCs were present in receiving groundwater adjacent to underground infiltration basins, compared to inflow. However, some contaminants were present at relatively high concentrations compared to stormwater flowing into the basins. This is particularly true for pesticides and their degradants. Fewer TrOCs were detected in interstitial water collected near stormwater ponds compared to inflow and outflow. The presence and concentrations of TrOCs in outflow from ponds was generally similar to or higher than what was observed in inflow. The data collected as part of this study can be used to guide future research or monitoring in an effort to better understand TrOC fate and transport in the environment via stormwater BMPs. Specifically, more work is needed to track parcels of water as they flow through BMPs to better quantify transport and degradation of TrOCs, monitor flow into and out of ponds for mass balance calculations, and conduct tracer tests to better quantify the amount of water that monitoring wells are intercepting from underground infiltration basins. These results have been shared in multiple presentations and in meetings with high school teachers to develop age-appropriate curriculum to highlight the role of individuals in reducing and preventing stormwater contamination. The ongoing pandemic hindered some of these efforts (cancelled conferences; suspended MN Water Roundtable meetings; pre-occupation with teachers moving materials online), however, as dissemination activities become more common in the near future, we will continue to educate stakeholders and educators about the root causes and effects of urban stormwater contamination.
Minnesota↗