Browsing by Subject "Sediment"

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Abiotic transformations of pesticides in prairie potholes
(2012-08) Zeng, Teng
The prairie pothole region (PPR) is among the most extensively altered ecosystems on Earth. This region covers approximately 780,000 km2 of central North America, and contains numerous glacially formed wetlands embedded in an agricultural landscape. These wetlands, commonly known as prairie pothole lakes (PPLs), provide essential ecosystem services. Over the last 150 years, agricultural drainage has resulted in severe loss of native prairie wetlands. The remaining PPLs continue to be threatened by nonpoint source pesticide pollution from agriculture. Currently, little is known about the fate and persistence of pesticides in PPLs. In this work, the abiotic transformations of commonly used pesticides in PPL sediment porewaters and surface water were explored. Chloroacetanilide and dinitroaniline pesticides were found to react rapidly with naturally abundant reduced sulfur species (i.e., hydrogen sulfide and polysulfides) in sediment porewaters via nucleophilic substitution and reduction reactions, respectively. Dissolved organic matter (DOM) was also found to play a vital role in the reductive transformation. Next, the photodegradation of a suite of pesticides was investigated in PPL surface water under both simulated and natural sunlight. Enhanced pesticide removal rates pointed to the importance of indirect photolysis pathways involving photochemically produced reactive intermediates such as singlet oxygen and triplet excited-state DOM. Finally, the sedimentary sulfur speciation was examined by sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy. Sulfur species in PPL sediments were found to consist of organic (di)sulfides, sulfonate, sulfate, and the mineral pyrite. Notably, the fractional abundances of reduced and oxidized sulfur species fluctuate on a seasonal basis.
The Contribution of Black Carbon to Bulk Lake Superior Sediment
(2014) Rhoades, Brandon
The Contribution of Black Carbon to Bulk Lake Superior Sediment
(2014) Rhoades, Brandon; Minor, Elizabeth C.
Developing a Diagnostic Tool for Assessing Excessive Sediment Harm to Stream Communities
(University of Minnesota Duluth, 2013) Brady, Valerie; Herrera, Larissa
Excess sediment is a top cause of impairment in U.S. rivers and streams. A number of streams on the north shore of Lake Superior’s western arm are on the Minnesota Pollution Control Agency’s impaired waters list due to turbidity problems. The underlying geology of the north shore, in addition to the steep slopes of the Lake Superior escarpment, forms a stream base vulnerable to erosion and excessive sediment deposition in streams. This vulnerability is created, at least in part, by an area of clay loam soil that many north shore stream channels intersect as they come down the escarpment to the shore of Lake Superior. The steep slopes cause high stream velocities which, combined with the high erodability of this soil layer, create high erosion potentials, particularly on outside channel bends. The increased fine sediments traveling through and accumulating in stream substrates potentially presents several problems for aquatic biota. Excess sediment deposits reduce habitat space for aquatic macroinvertebrates, which are vital components of the food web. In addition to potentially decreasing food sources for fish, the excess sediment deposits can bury fish spawning habitats. Even if the fish can clean off nesting areas, they will expend extra energy doing so. There are many stream condition indicators using stream fish or macroinvertebrates, but none address excess sediment specifically. In many areas of the country there are any number of human‐caused stressors affecting stream condition, including agricultural runoff, high stormwater discharges, loss of stream shoreline habitat, deforestation, development, and industrial discharges. When there are many stressors impacting streams, it is hard to differentiate among them to determine which stressors are creating which problems for stream biota. While some north shore streams have non‐turbidity impairments, there are considerably fewer than in other parts of the country. The dominance of erosion‐based impairments provided the opportunity to develop an indicator diagnostic of excessive sediment deposition in stream substrate as the cause of biotic impairment in north shore streams. We selected stream macroinvertebrates for indicator development for several reasons. They are less mobile than fish, meaning that they have limited ability to escape from disturbance, and even more limited ability to return after a disturbance ceases (at least until the next generation begins). Macroinvertebrates are easy to collect, are present in relatively high abundances, and have high morphological diversity. For all of these reasons, macroinvertebrates are commonly used in stream condition assessments, and their use is ubiquitous across the US and across agencies. Because most agencies collect stream macroinvertebrate information already, their use to create a diagnostic indicator could allow agencies and managers to get more information out of data they already have, without the need for additional sampling. The goal of this project was to develop a suite of stream macroinvertebrate metrics diagnostic of invertebrate community impairment caused by excessive fine sediment deposition in stream substrate; in other words, burial or partial burial of streambed rocks by sand, silt, and clay. Such a diagnostic tool would aid managers in their stream assessment work. While similar projects have been previously attempted (and failed) in other parts of the country, most have been in areas suffering from a number of stressors, making development of an indicator diagnostic of just sediment impairment more difficult. Our hope in attempting such work using north shore streams was that the relative lack of other stressors in northeastern Minnesota would make the development of such an indicator more possible. Having such an indicator should help agencies make a stronger connection between the Total Maximum Daily Load (TMDL) turbidity measurements and sediment deposition presumed to be causing harm to stream biota.
Effects of Aquaculture on Mine Pit Lakes near Chisolm, MN: Restoration of Twin City-South pit lake by fallowing and status of Fraser pit lake
(University of Minnesota Duluth, 1995) Axler, Richard P; Yokom, Shane; Tikkanen, Craig A; Henneck, Jerald; McDonald, Michael E
Net-pen salmonid aquaculture was carried out from 1988 to 1993 in the Twin City-South mine pit lake on the Mesabi Iron Range in northeastern Minnesota. A water quality controversy enveloped the aquaculture operation from its inception in 1988. In 1992 the Minnesota Pollution Control Agency mandated that all intensive aquaculture operations in the Twin City - South mine pit lake be terminated by July 1993 and that restoration to baseline (i.e. preaquaculture) conditions be demonstrated within three years. This "fallowing" has led to a rapid recovery to near baseline water quality conditions and an oligomesotrophic, i.e. unproductive, status. Water column improvement in regard to phosphorus and hypolimnetic oxygen concentrations has been particularly rapid. Although baseline conditions were not well defined for TC-S, the P budget for the lake in September and November 1994 was typical of reference pit lakes in the area. Oxygen concentrations in near-bottom water remained above 5 mg02/L in November 1994 even without artificial mixing or aeration during the 1994 growing season. Algal growth was low in 1993, as expected due to artificial mixing, and remained low in 1994 without any artificial mixing. Ammonium has been naturally converted to nitrate which is decreasing faster than expected and at a rate similar to its increase during intensive aquaculture. More rapid reductions in water column phosphorus and nitrogen might have been accomplished during the first summer by allowing the lower hypolimnion to become anoxic in order to promote denitrification and minimize sediment resuspension. The natural burial of sedimented aquaculture wastes due to high ambient rates of erosion of inorganic sediment from the basin walls has effectively minimized sediment nutrient transport to the overlying water column. Fallowing for several years appears to be an effective method for lake restoration of these pit lakes. Our data, and our analysis of the NPDES monitoring data, has shown no change in the water quality of Chisholm's drinking water source, the Fraser pit lake, attributable to aquaculture impacts. This, and no apparent change in the water quality of two nearby pit lakes, Grant and Ironworld in recent years, suggests little or no significant off-site migration of aquaculturally impacted water.
Field Guide for Maintaining Rural Roadside Ditches
(2014) Brady, Valerie; Axler, Richard P; Schomberg, Jesse
A Freshwater Mussel Survey of the Shingobee River Cass and Hubbard Counties, Minnesota
(University of Minnesota Duluth, 2001) Anderson, Lindsay P; Reed, Jane; Axler, Richard P
A freshwater mussel survey of the Shingobee River was conducted in September, 2000, in order to determine the status of Lasmigona compressa, a Regional Forester Sensitive Species and Minnesota Species of Special Concern. Approximately 6.5 miles of the Shingobee River was surveyed from the mouth at Leech Lake upstream to the large beaver pond approximately 0.75 miles downstream of Shingobee Lake. One Pyganodon grandis was found within the survey area. No mussel beds were found in the survey area. One Lasmigona compressa and 35 Lampsilis radiata siliquiodea were found upstream of Shingobee Lake after the initial survey was completed. Water and sediment samples were collected at four sites along the length of the river. Water samples were analyzed for temperature, pH, specific conductance, alkalinity, hardness, total phosphorus, total ammonium nitrogen (TAN), nitrate + nitrite nitrogen, turbidity, calcium, magnesium, sodium and potassium. Sediment samples were analyzed for temperature, pH, TAN and un-ionized ammonia. Evidence exists for a recent decline in mussel abundance and diversity in the river. Potential causes for this decline are discussed.
Hydrodynamic separator sediment washout testing.
(2010-07) Saddoris, David Allan
Hydrodynamic separators are widely used in urban areas for removal of suspended sediments and floatables from stormwater due to limited land availability for the installation of above ground stormwater best management practices (BMPs). Hydrodynamic separators are often sized based on relatively frequent storm events. However, during less frequent storm events, device design treatment rates are exceeded and previously captured sediments can be washed out of the devices. To study the potential for scour and washout of previously deposited sediments in the sumps of hydrodynamic separators under high flow conditions during infrequent storm events, sediment washout testing methods using mass balance were developed for both controlled field testing and laboratory testing. The developed testing methods were utilized to conduct sediment washout testing on three full scale hydrodynamic separators: 1) an Environment21 V2B1 Model 4, 2) a STC1200 Stormceptor and 3) a 6-ft Downstream Defender. All three devices were tested in the laboratory. The Environment21 V2B1 device was also tested in the field. In addition to full scale testing, two scale models were constructed and tested in the laboratory. Previous work by others on describing sediment washout in standard stormwater sumps was applied to data obtained from the sediment washout tests to develop sediment washout functions which incorporate non-dimensional parameters. Washout functions were developed for each of the devices tested in the laboratory and the field, as well as for a modified ecoStorm device previously tested by others. The washout functions that were developed can be incorporated, along with removal efficiency functions, into continuous urban runoff models to predict maintenance schedules for hydrodynamic separator devices.
Identification and Characterization of Phosphorus Composition in Lake Superior and St. Louis River Estuary Sediments Using Phosphorus Nuclear Magnetic Resonance Spectroscopy
(2017-12) Schoechert, Hannah
Phosphorus has been a contaminant of concern for many freshwater lakes for decades. Excessive bioavailable phosphorus often leads to the eutrophication of a particular body of water. Information on the specific chemical composition of phosphorus in sediment is fundamental to understanding its bioavailability and eutrophication potential to a lake ecosystem. A single-step sodium hydroxide-ethylenediaminetetraacetic acid (NaOH-EDTA) extraction and a phosphorus nuclear magnetic resonance (31P NMR) spectroscopy protocol were developed and subsequently performed on St. Louis River Estuary (SLRE) and Chequamegon Bay (CB) sediment samples. Results show the presence of phosphorus-containing compounds comparable to other oligotrophic waterbodies, and compounds typically detected in sediment samples from eutrophic lakes were not detected in any sample. For the CB samples, as the water depth increased, so did the number of peaks identified. Similarly, as the number of peaks increased, there was an increase in relative abundance of different phosphorus. For the SLRE samples, it was observed that the phosphorus composition in the sediment mirrored the phosphorus sediment composition from the Chequamegon Bay samples, suggesting there are similar hydrological conditions between the two sites.
Identification of Methylmercury Export Hotspots in an Industrially-Influenced Great Lakes Coastal Wetland
(2020-12) White, Amber
The production and export of methylmercury (MeHg) is a critical first step to accumulation of mercury (Hg) in the lower food web and subsequent magnification in game fish. The purpose of this thesis was to identify areas of MeHg production and export in a freshwater estuary with a history of industrial influence by using ecological boundary delineations. Sediment, porewater and surface water was collected over two seasons from eleven sites encompassing four high-carbon sheltered embayments, two intermediate-carbon clay-influenced bays, and five low-carbon industrially influenced bays in the St. Louis River Estuary (Duluth, Minnesota). Ecologically delineated areas contained characteristically different quantities of Hg and MeHg and appear to be a useful framework for identifying locations likely to experience a net production of MeHg. The results provide a basis for understanding how MeHg can move through freshwater aquatic environments with complex hydrogeochemistry and could form the basis for effective resource management decisions.
Identifying The Impacts Of Excess Fine Sediment On Benthic Macroinvertebrate Communities
(2016-03) Herrera, Larissa
Many streams throughout the United States are negatively impacted by excess fine sediments (sand, silt, and clay). Benthic macroinvertebrates are a commonly-used tool to assess stream condition; however, current methodologies typically are not able to distinguish among stressors. Previous studies have correlated macroinvertebrate communities and traits with excess fine sediments, demonstrating that aquatic macroinvertebrates are sensitive to deposited fine sediment and the assemblages will shift in response. Western Lake Superior streams have a wide range of fine sediment amounts due to clay and sand soils, but have low amounts of other stressors, and thus are a good region to investigate relationships between macroinvertebrate traits and fine sediments. Data were collected from 22 stream sites located along the north shore of Lake Superior in 2010. The data collected in 2010 did not have the desired gradient of fine sediment due to wet conditions that year; therefore, the data were supplemented with data collected by NRRI personnel in earlier years (1997 – 2008). The five sediment stressors used in analyses included percent embeddedness, depth of fine sediments, total percent fine sediments, percent sand, and a combined sediment index created using normalized and transformed embeddedness, depth of fine sediments and total percent fine sediments. Fifty-seven specific taxonomic groups and macroinvertebrate physical and behavioral characteristics (traits) were tested as potential response metrics in linear regressions. In addition, TITAN analyses were used to look for thresholds or sediment stressor values at which a taxon increases greatly, decreases greatly, or disappears from a community. Both the linear regressions and TITAN analyses showed a change in the community structure under conditions of excess sediment in the form of embeddedness, total fines, depth of fines, and/or the combined sediment index. The TITAN analyses also showed a change in the community structure due to increasing proportion sand in the streambed. Furthermore, the analyses identified potential characteristics that may specifically make a particular macroinvertebrate more or less vulnerable to excess fine sediments.
An Investigation into the Biomarker Potential of Highly Branched Isoprenoids in Northern Minnesota Lacustrine Sediments
(2022-08) Hanson, Bennett
Highly Branched Isoprenoids (HBIs) are isoprene-based lipids synthesized by diatoms. HBIs are commonly used as sea-ice proxies in marine environments where their presence is indicative of marginal ice zones. Historical data on Ice cover in the Laurentian Great Lakes is sparse and only spans from the mid 1960’s to present day. This study aims to expand the biomarker potential of HBIs to apply them as a proxy for ice cover on Lake Superior. Seven study sites around Lake Superior were selected and studied to determine which freshwater HBIs were present, and at what concentration they were found. Each site was sampled twice, in the summer and in the winter to determine if seasonal conditions affect HBI production of diatom communities. The HBI suite at each site is characterized by gas chromatography mass spectrometry (GC-MS) analysis of the nonpolar extractable fraction of the sediments and the genera of diatoms present at each site are characterized by visual identification. In addition, microcosm studies of Nitzschia and Fragilaria are isolated from the Two Harbors study site and are analyzed to determine the HBI suites produced by them. Overall, eight distinct HBIs were identified from the seven study sites, in concentrations ranging from 0.1-0.9 µg g-1 dry sediment. Four distinct HBIs were identified from the microcosm cultures including three distinct C30 and one distinct C25 HBIs. HBIs show a potential to be correlated to environmental conditions, though future experiments must be conducted to develop this relationship.
Limnological Re-Sampling of Chisolm Area Mine Pit Lakes with Reference to Former Aquaculture Impacts
(University of Minnesota Duluth, 2000) Axler, Richard P; Henneck, Jerald
Limnological surveys were conducted on two mine pit lakes (Twin City-South and Sherman) used for intensive netpen salmonid aquaculture over the period 1988-1995 and an adjacent pit lake (Fraser) used for drinking water by Chisholm, Minnesota. A water quality controversy had enveloped the aquaculture operation from its inception in 1988 to its bankruptcy in 1995. All intensive aquaculture operations in the Twin City-South pitlake were terminated in mid-1993 as mandated by the Minnesota Pollution Control Agency (MPCA) in order to determine if water quality could be returned to baseline values within three years (a condition of continued operation in the Sherman pit lake). The MPCA mandated that restoration to baseline (i.e. pre-aquaculture) conditions be demonstrated within three years. This "fallowing" led to a rapid recovery to near baseline water quality conditions and an oligomesotrophic, i.e. unproductive, status. Algal growth was low in 1993, due to light - limitation from artificial mixing, but remained low in 1994 without any management due to renewed P-limitation. Water column improvement in regard to phosphorus and hypolimnetic oxygen concentrations was particularly rapid. Although baseline conditions were not well defined for TC-S, the P budget for the lake after 18 months was typical of reference pit lakes in the area and oxygen concentrations in near-bottom water remained above 5 mg02/L without artificial mixing or aeration during the next growing season. Waste product ammonium was naturally nitrified to nitrate which decreased at a rate faster than expected, and similar to its increase during intensive aquaculture. More rapid reductions in water column phosphorus and nitrogen might have been accomplished during the first, summer by allowing the lower hypolimnion to become anoxic in order to promote denitrification and minimize sediment resuspension. Unfortunately these were precluded by the regulatory standards. The natural burial of sedimented aquaculture wastes due to high ambient rates of erosion of inorganic sediment from the basin walls effectively minimized sediment nutrient transport to the overlying water column and sediment oxygen demand.
Method for the Determination of Polycyclic Aromatic Hydrocarbons (PAHs) in Sediment
(University of Minnesota Duluth, 1999-01-04) Lodge, Keith B; Moser, I. M; Kohlbry, S. W
Minnesota Taconite Workers Health Study: Environmental Study of Airborne Particulate Matter in Mesabi Iron Range Communities and Taconite Processing Plants - Lake Sediment Study
(University of Minnesota Duluth, 2019-12) Zanko, Lawrence M; Reavie, Euan D; Post, Sara P
Atmospheric deposition of airborne particulate matter such as fugitive dust contributes to sediment that accumulates at the bottom of a lake. Because of this phenomenon, lake sediment can provide an historic mineralogical and chemical record of what may have been in the air at the time of its atmospheric deposition. This point is important, because the NRRI’s role in the Minnesota Taconite Workers Health Study (MTWHS) was to not only help answer the question “What is in the air?” by conducting present-day in-plant and community air sampling, but – and even more challengingly – to potentially answer the question “What was in the air, when?” by collecting and analyzing historic samples. Lake sediment was the only historic sampling medium available that could allow the investigators to make an attempt to assess what might have been present in the air in the past on Minnesota’s Mesabi Iron Range (MIR). The NRRI therefore core-sampled, age-dated, and characterized intervals of sediment from two MIR lakes – Silver Lake in Virginia, on the central MIR, and “North-of-Snort” Lake on the eastern end of the MIR, near Babbitt (Fig. i). The objective was to determine if fugitive mineral dust generated by past iron ore/taconite mining activity could be discerned in mineral particulate matter (PM) deposited and preserved in the sediment of both lakes.
Paleolimnology of the St. Louis River Estuary
(University of Minnesota Duluth, 2016-05) Reavie, Euan D; Alexson, Elizabeth; Axler, Richard P; Yost, Chad; Ladwig, Jammi; Nurse, Andrea; Estepp, Lisa; Krasutsky, Pavel A; Kennedy, Kathleen; Yemets, Sergiy; Engstrom, Daniel R
The St. Louis River Watershed which drains to the St. Louis River and its associated estuary near Lake Superior has more than 150 years of human development history since Euro‐Americans first settled there, resulting in critical water quality impacts. In 1987, the U.S. Environmental Protection Agency designated the St. Louis River as an Area of Concern primarily due to that history which entailed inappropriate discharge of untreated wastewater and debris from poor industrial and community practices. The organic matter loading from inadequate treatment of sewage and paper mill products along with the dumping of woody debris from sawmills contributed to low oxygen levels in the river. The result included devastating impacts to the entire food web from the bacteria to vegetation to invertebrates to fish. Concurrently, poorly managed stormwater runoff from this post‐logged, barren landscape contributed excessive loading of suspended sediments resulting in increased turbidity and nutrient concentrations (e.g., phosphorus, nitrogen) to the river. Since then, government and private entities have taken action to restore the water quality in the St. Louis River Estuary, and to eventually remove the eight remaining SLRAOC BUIs. This summary focuses on the research documenting water quality changes over time associated with the excessive loading of sediment and nutrients BUI.
Performance Assessment of Underground Stormwater Treatment Devices
(Minnesota Department of Transportation, 2007-11) Wilson, Matthew; Gulliver, John S.; Mohseni, Omid; Hozalski, Raymond M.
The objectives of this research were threefold: to investigate the feasibility and practicality of field testing to assess the performance of underground devices used for stormwater treatment in urban areas; evaluate the effects of sediment size and stormwater flow rate on the performance of four different manufactured devices; and to develop a universal approach for predicting the performance of a device for any given application. Field testing that used a controlled and reproducible synthetic storm event that contained sediment of a fixed size distribution and concentration fed to pre-cleaned devices led to the development of uniform performance models. The results of this project show that controlled field tests are a practical, robust and accurate means of determining an underground device's performance, based on solid size distribution and density of the influent, in addition to water discharge and temperature. This premise was successfully verified in field tests on four devices and in laboratory tests on two devices. The resulting protocol and results of testing will be a useful tool for consultants, manufacturers, local governments, and state agencies for selecting, sizing, and evaluating stormwater treatment technologies to protect water resources.
Prioritizing stream restoration: a decision support tool for use in restoring waters impaired by excess sediment in the Blue Earth River Basin of Minnesota
(2013-06) Presnail, Mary Louise
The hydrology of the Blue Earth River Basin has been dramatically altered following European settlement in the mid-to-late 1800's. Land use change has resulted in hydrologic instability leading to streambank and bluff erosion and increased sediment transport (Magner et al., 2003). Hydrologic change has led to an increase in Turbidity, or cloudiness of the river commonly measured as total suspended sediment (TSS). Excessive turbidity in water can be harmful to both humans (if used for drinking water) and aquatic life. In the Greater Blue Earth River Basin, there are 39 stream/river reaches that fail to meet the state's water quality standards for Turbidity, which is 90 parts per million TSS (MPCA, 2005). The purpose of this study is to create a tool that researchers can use to prioritize stream restoration in the Blue Earth River Basin in a relatively quick, productive and cost-effective way. The tool created will help prioritize stream sites for restoration based on a set of decision support metrics. A field test of the tool was conducted on two tributaries to the Blue Earth; Elm and Center Creek. The tool was tested on a total of 30 sites from these two tributaries. The future goal for this tool is for it to be used to help local officials prioritize restoration on unstable areas throughout the Blue Earth River Basin that are actively eroding and contributing sediment to the Blue Earth River.
RI-68 Quaternary Lithostratigraphic Units of Minnesota
(Minnesota Geological Survey, 2016-03) Johnson, Mark D.; Adams, Roberta S.; Gowan, Angela S.; Harris, Kenneth L.; Hobbs, Howard C.; Jennings, Carrie E.; Knaeble, Alan R.; Lusardi, Barbara A.; Meyer, Gary N.;
Much of Minnesota is covered by sediment of Quaternary age that was deposited during numerous glaciations by ice, wind, and water. In this report, we follow guidelines of the North American Stratigraphic Code (North American Commission on Stratigraphic Nomenclature, 2005) to create a framework for establishing formal lithostratigraphic units in Minnesota. We evaluate over 100 lithostratigraphic units that have been identified in Minnesota. Eighty (80) units are considered to be useful lithostratigraphic units of formation and member rank, and these are formally accepted in this report or are recommended to be so in future publications. These 80 units include previously named formal lithostratigraphic units that are recognized and accepted as originally defined, but also formally defined units that we have revised or redefined to better fit into our stratigraphic framework. The remaining lithostratigraphic units have been used informally in earlier reports or are newly named in this report. Additional units that are no longer considered necessary as lithostratigraphic units are abandoned in this report. These units include previously used units of both formal and informal status. Of the 80 lithostratigraphic units recommended to be retained, 47 are formally defined, revised, or redefined in this report. The remaining 33 units are recommended to be formally named in a future Minnesota Geological Survey Report of Investigations.
Sources, Transport, and Sediment-Water Distributions of Contaminants of Emerging Concern in a Mixed-Use Watershed
(2015-06) Fairbairn, David Joel
Understanding the sources and transport of contaminants of emerging concern (CECs) is crucial for risk assessment and mitigation. The goal of this research was to augment this knowledge by characterizing the spatiotemporal variability of a diverse set of CECs in a mixed land-use watershed. The study area (South Zumbro Watershed, Minnesota) presented a gradient of land uses that facilitated the investigation of agricultural and urban/residential sources and transport of CECs. Concentrations and loadings of CECs in water samples were analyzed in light of spatial, temporal, hydrologic, and physicochemical variables. Contaminant mass balances were analyzed to characterize the proportional sources and instream transport of CECs. Sediment-water distributions of CECs were assessed in terms of their magnitude, variability, and predictability. Three distinct CEC groups emerged with respect to sources, transport, and seasonal/temporal patterns. The first group (i.e., atrazine, acetochlor, metolachlor, and daidzein) was characterized by agricultural/upstream-dominated sources and transport. These CECs were input primarily via upstream routes with loadings and concentrations that were greatest during high flows. For the second group (i.e., acetaminophen, trimethoprim, DEET, caffeine, cotinine, and mecoprop), a mix of wastewater and runoff transport was demonstrated by frequent detections in effluent and upstream samples, with peak loadings/concentrations associated with high flows and areas of greater population density/development. For the third group (i.e., sulfamethoxazole, carbamazepine, erythromycin, tylosin, carbaryl, and 4-nonylphenol), the detections, concentrations, and loadings were explained by effluent-dominated sources and transport. These CECs showed expected trends of stable loading across events, with the greatest concentrations and detection frequencies associated with low flows and the wastewater treatment plant. Average measured sediment-water distributions exceeded equilibrium hydrophobic-based predictions for five of seven detected CECs by at least an order of magnitude. The consistency and predictability of the measured distributions improved with increasing CEC hydrophobicity and persistence. Thus, spatiotemporal analysis can be used to characterize and track CEC sources and transport, even for ubiquitous CECs. These results augment existing knowledge of CEC sources, fate, and transport by describing dominant sources, transport, and temporal patterns for different types of CECs. This will enhance monitoring, exposure/risk assessments, and management of CECs in surface water ecosystems.

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