Jeffrey H. Writer

Sewage contamination in the upper Mississippi River as measured by the fecal sterol, coprostanol

Abstract The molecular sewage indicator, coprostanol, was measured in bed sediments of the Mississippi River for the purpose of determining sewage contamination. Coprostanol is a non-ionic, non-polar, organic molecule that associates with sediments in surface waters, and concentrations of corpostanol in bed sediments provide an indication of long-term sewage loads. Because coprostanol concentrations are dependent on particle size and percent organic carbon, a ratio between coprostanol (sewage sources) and cholestanol + cholesterol (sewage and non-sewage sources) was used to remove the biases related to particle size and percent organic carbon. The dynamics of contaminant transport in the Upper Mississippi River are influenced by both hydrologic and geochemical parameters. A mass balance model incorporating environmental parameters such as river and tributary discharge, suspended sediment concentration, fraction of organic carbon, sedimentation rates, municipal discharges and coprostanol decay rates was developed that describes coprostanol concentrations and therefore, expected patterns of municipal sewage effects on the Upper Mississippi River. Comparison of the computed and the measured coprostanol concentrations provides insight into the complex hydrologic and geochemical processes of contaminant transport and the ability to link measured chemical concentrations with hydrologic characteristics of the Mississippi River.

Anthropogenic tracers, endocrine disrupting chemicals, and endocrine disruption in Minnesota lakes

Concentrations of endocrine disrupting chemicals and endocrine disruption in fish were determined in 11 lakes across Minnesota that represent a range of trophic conditions and land uses (urban, agricultural, residential, and forested) and in which wastewater treatment plant discharges were absent. Water, sediment, and passive polar organic integrative samplers (POCIS) were analyzed for steroidal hormones, alkylphenols, bisphenol A, and other organic and inorganic molecular tracers to evaluate potential non-point source inputs into the lakes. Resident fish from the lakes were collected, and caged male fathead minnows were deployed to evaluate endocrine disruption, as indicated by the biological endpoints of plasma vitellogenin and gonadal histology. Endocrine disrupting chemicals, including bisphenol A, 17β-estradiol, estrone, and 4-nonylphenol were detected in 90% of the lakes at part per trillion concentrations. Endocrine disruption was observed in caged fathead minnows and resident fish in 90% of the lakes. The widespread but variable occurrence of anthropogenic chemicals in the lakes and endocrine disruption in fish indicates that potential sources are diverse, not limited to wastewater treatment plant discharges, and not entirely predictable based on trophic status and land use.

Fate of 4-nonylphenol and 17β-estradiol in the Redwood River of Minnesota.

The majority of previous research investigating the fate of endocrine-disrupting compounds has focused on single processes generally in controlled laboratory experiments, and limited studies have directly evaluated their fate and transport in rivers. This study evaluated the fate and transport of 4-nonylphenol, 17β-estradiol, and estrone in a 10-km reach of the Redwood River in southwestern Minnesota. The same parcel of water was sampled as it moved downstream, integrating chemical transformation and hydrologic processes. The conservative tracer bromide was used to track the parcel of water being sampled, and the change in mass of the target compounds relative to bromide was determined at two locations downstream from a wastewater treatment plant effluent outfall. In-stream attenuation coefficients (k(stream)) were calculated by assuming first-order kinetics (negative values correspond to attenuation, whereas positive values indicate production). Attenuation of 17β-estradiol (k(stream) = -3.2 ± 1.0 day(-1)) was attributed primarily due to sorption and biodegradation by the stream biofilm and bed sediments. Estrone (k(stream) = 0.6 ± 0.8 day(-1)) and 4-nonylphenol (k(stream) = 1.4 ± 1.9 day(-1)) were produced in the evaluated 10-km reach, likely due to biochemical transformation from parent compounds (17β-estradiol, 4-nonylphenolpolyethoxylates, and 4-nonyphenolpolyethoxycarboxylates). Despite attenuation, these compounds were transported kilometers downstream, and thus additive concentrations from multiple sources and transformation of parent compounds into degradates having estrogenic activity can explain their environmental persistence and widespread observations of biological disruption in surface waters.

Biodegradation and Attenuation of Steroidal Hormones and Alkylphenols by Stream Biofilms and Sediments

Biodegradation of select endocrine-disrupting compounds (17β-estradiol, estrone, 17α-ethynylestradiol, 4-nonylphenol, 4-nonylphenolmonoexthoylate, and 4-nonylphenoldiethoxylate) was evaluated in stream biofilm, sediment, and water matrices collected from locations upstream and downstream from a wastewater treatment plant effluent discharge. Both biologically mediated transformation to intermediate metabolites and biologically mediated mineralization were evaluated in separate time interval experiments. Initial time intervals (0-7 d) evaluated biodegradation by the microbial community dominant at the time of sampling. Later time intervals (70 and 185 d) evaluated the biodegradation potential as the microbial community adapted to the absence of outside energy sources. The sediment matrix was more effective than the biofilm and water matrices at biodegrading 4-nonylphenol and 17β-estradiol. Biodegradation by the sediment matrix of 17α-ethynylestradiol occurred at later time intervals (70 and 185 d) and was not observed in the biofilm or water matrices. Stream biofilms play an important role in the attenuation of endocrine-disrupting compounds in surface waters due to both biodegradation and sorption processes. Because sorption to stream biofilms and bed sediments occurs on a faster temporal scale (<1 h) than the potential to biodegrade the target compounds (50% mineralization at >185 d), these compounds can accumulate in stream biofilms and sediments.

Role of biofilms in sorptive removal of steroidal hormones and 4-nonylphenol compounds from streams.

Stream biofilms play an important role in geochemical processing of organic matter and nutrients, however, the significance of this matrix in sorbing trace organic contaminants is less understood. This study focused on the role of stream biofilms in sorbing steroidal hormones and 4-nonylphenol compounds from surface waters using biofilms colonized in situ on artificial substrata and subsequently transferred to the laboratory for controlled batch sorption experiments. Steroidal hormones and 4-nonylphenol compounds readily sorb to stream biofilms as indicated by organic matter partition coefficients (K(om), L kg(-1)) for 17β-estradiol (10(2.5-2.8) L kg(-1)), 17α-ethynylestradiol (10(2.5-2.9) L kg(-1)), 4-nonylphenol (10(3.4-4.6) L kg(-1)), 4-nonylphenolmonoethoxylate (10(3.5-4.0) L kg(-1)), and 4-nonylphenoldiethoxylate (10(3.9-4.3) L kg(-1)). Experiments using water quality differences to induce changes in the relative composition of periphyton and heterotrophic bacteria in the stream biofilm did not significantly affect the sorptive properties of the stream biofilm, providing additional evidence that stream biofilms will sorb trace organic compounds under of variety of environmental conditions. Because sorption of the target compounds to stream biofilms was linearly correlated with organic matter content, hydrophobic partition into organic matter appears to be the dominant mechanism. An analysis of 17β-estradiol and 4-nonylphenol hydrophobic partition into water, biofilm, sediment, and dissolved organic matter matrices at mass/volume ratios typical of smaller rivers showed that the relative importance of the stream biofilm as a sorptive matrix was comparable to bed sediments. Therefore, stream biofilms play a primary role in attenuating these compounds in surface waters. Because the stream biofilm represents the base of the stream ecosystem, accumulation of steroidal hormones and 4-nonylphenol compounds in the stream biofilm may be an exposure pathway for organisms in higher trophic levels.

Widespread occurrence of neuro-active pharmaceuticals and metabolites in 24 Minnesota rivers and wastewaters.

Concentrations of 17 neuro-active pharmaceuticals and their major metabolites (bupropion, hydroxy-bupropion, erythro-hydrobupropion, threo-hydrobupropion, carbamazepine, 10,11,-dihydro-10,11,-dihydroxycarbamazepine, 10-hydroxy-carbamazepine, citalopram, N-desmethyl-citalopram, fluoxetine, norfluoxetine, gabapentin, lamotrigine, 2-N-glucuronide-lamotrigine, oxcarbazepine, venlafaxine and O-desmethyl-venlafaxine), were measured in treated wastewater and receiving surface waters from 24 locations across Minnesota, USA. The analysis of upstream and downstream sampling sites indicated that the wastewater treatment plants were the major source of the neuro-active pharmaceuticals and associated metabolites in surface waters of Minnesota. Concentrations of parent compound and the associated metabolite varied substantially between treatment plants (concentrations±standard deviation of the parent compound relative to its major metabolite) as illustrated by the following examples; bupropion and hydrobupropion 700±1000 ng L(-1), 2100±1700 ng L(-1), carbamazepine and 10-hydroxy-carbamazepine 480±380 ng L(-1), 360±400 ng L(-1), venlafaxine and O-desmethyl-venlafaxine 1400±1300 ng L(-1), 1800±2300 ng L(-1). Metabolites of the neuro-active compounds were commonly found at higher or comparable concentrations to the parent compounds in wastewater effluent and the receiving surface water. Neuro-active pharmaceuticals and associated metabolites were detected only sporadically in samples upstream from the effluent outfall. Metabolite to parent ratios were used to evaluate transformation, and we determined that ratios in wastewater were much lower than those reported in urine, indicating that the metabolites are relatively more labile than the parent compounds in the treatment plants and in receiving waters. The widespread occurrence of neuro-active pharmaceuticals and metabolites in Minnesota effluents and surface waters indicate that this is likely a global environmental issue, and further understanding of the environmental fate and impacts of these compounds is warranted.

In-stream attenuation of neuro-active pharmaceuticals and their metabolites.

In-stream attenuation was determined for 14 neuro-active pharmaceuticals and associated metabolites. Lagrangian sampling, which follows a parcel of water as it moves downstream, was used to link hydrological and chemical transformation processes. Wastewater loading of neuro-active compounds varied considerably over a span of several hours, and thus a sampling regime was used to verify that the Lagrangian parcel was being sampled and a mechanism was developed to correct measured concentrations if it was not. In-stream attenuation over the 5.4-km evaluated reach could be modeled as pseudo-first-order decay for 11 of the 14 evaluated neuro-active pharmaceutical compounds, illustrating the capacity of streams to reduce conveyance of neuro-active compounds downstream. Fluoxetine and N-desmethyl citalopram were the most rapidly attenuated compounds (t1/2 = 3.6 ± 0.3 h, 4.0 ± 0.2 h, respectively). Lamotrigine, 10,11,-dihydro-10,11,-dihydroxy-carbamazepine, and carbamazepine were the most persistent (t1/2 = 12 ± 2.0 h, 12 ± 2.6 h, 21 ± 4.5 h, respectively). Parent compounds (e.g., buproprion, carbamazepine, lamotrigine) generally were more persistent relative to their metabolites. Several compounds (citalopram, venlafaxine, O-desmethyl-venlafaxine) were not attenuated. It was postulated that the primary mechanism of removal for these compounds was interaction with bed sediments and stream biofilms, based on measured concentrations in stream biofilms and a column experiment using stream sediments.

The role of precipitation type, intensity, and spatial distribution in source water quality after wildfire

Storms following wildfires are known to impair drinking water supplies in the southwestern United States, yet our understanding of the role of precipitation in post-wildfire water quality is far from complete. We quantitatively assessed water-quality impacts of different hydrologic events in the Colorado Front Range and found that for a three-year period, substantial hydrologic and geochemical responses downstream of a burned area were primarily driven by convective storms with a 30 min rainfall intensity >10 mm h?1. These storms, which typically occur several times each year in July?September, are often small in area, short-lived, and highly variable in intensity and geographic distribution. Thus, a rain gage network with high temporal resolution and spatial density, together with high-resolution stream sampling, are required to adequately characterize post-wildfire responses. We measured total suspended sediment, dissolved organic carbon (DOC), nitrate, and manganese concentrations that were 10?156 times higher downstream of a burned area compared to upstream during relatively common (50% annual exceedance probability) rainstorms, and water quality was sufficiently impaired to pose water-treatment concerns. Short-term water-quality impairment was driven primarily by increased surface runoff during higher intensity convective storms that caused erosion in the burned area and transport of sediment and chemical constituents to streams. Annual sediment yields downstream of the burned area were controlled by storm events and subsequent remobilization, whereas DOC yields were closely linked to annual runoff and thus were more dependent on interannual variation in spring runoff. Nitrate yields were highest in the third year post-wildfire. Results from this study quantitatively demonstrate that water quality can be altered for several years after wildfire. Because the southwestern US is prone to wildfires and high-intensity rain storms, the role of storms in post-wildfire water-quality impacts must be considered when assessing water-quality vulnerability.

Identifying Non-point Sources of Endocrine Active Compounds and Their Biological Impacts in Freshwater Lakes

Contaminants of emerging concern, particularly endocrine active compounds (EACs), have been identified as a threat to aquatic wildlife. However, little is known about the impact of EACs on lakes through groundwater from onsite wastewater treatment systems (OWTS). This study aims to identify specific contributions of OWTS to Sullivan Lake, Minnesota, USA. Lake hydrology, water chemistry, caged bluegill sunfish (Lepomis macrochirus), and larval fathead minnow (Pimephales promelas) exposures were used to assess whether EACs entered the lake through OWTS inflow and the resultant biological impact on fish. Study areas included two OWTS-influenced near-shore sites with native bluegill spawning habitats and two in-lake control sites without nearby EAC sources. Caged bluegill sunfish were analyzed for plasma vitellogenin concentrations, organosomatic indices, and histological pathologies. Surface and porewater was collected from each site and analyzed for EACs. Porewater was also collected for laboratory exposure of larval fathead minnow, before analysis of predator escape performance and gene expression profiles. Chemical analysis showed EACs present at low concentrations at each study site, whereas discrete variations were reported between sites and between summer and fall samplings. Body condition index and liver vacuolization of sunfish were found to differ among study sites as did gene expression in exposed larval fathead minnows. Interestingly, biological exposure data and water chemistry did not match. Therefore, although results highlight the potential impacts of seepage from OWTS, further investigation of mixture effects and life history factor as well as chemical fate is warranted.