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At least 847 records · Page 47Linked to original sources

USGS2005

A multivariate study of mangrove morphology (Rhizophora mangle) using both above and below-water plant architecture

A descriptive study of the architecture of the red mangrove, Rhizophora mangle L., habitat of Tampa Bay, FL, was conducted to assess if plant architecture could be used to discriminate overwash from fringing forest type. Seven above-water (e.g., tree height, diameter at breast height, and leaf area) and 10 below-water (e.g., root density, root complexity, and maximum root order) architectural features were measured in eight mangrove stands. A multivariate technique (discriminant analysis) was used to test the ability of different models comprising above-water, below-water, or whole tree architecture to classify forest type. Root architectural features appear to be better than classical forestry measurements at discriminating between fringing and overwash forests but, regardless of the features loaded into the model, misclassification rates were high as forest type was only correctly classified in 66% of the cases. Based upon habitat architecture, the results of this study do not support a sharp distinction between overwash and fringing red mangrove forests in Tampa Bay but rather indicate that the two are architecturally undistinguishable. Therefore, within this northern portion of the geographic range of red mangroves, a more appropriate classification system based upon architecture may be one in which overwash and fringing forest types are combined into a single, "tide dominated" category. ?? 2005 Elsevier Ltd. All rights reserved.

Estuarine, Coastal and Shelf Science↗

USGS2021

Effects-based monitoring of bioactive compounds associated with municipal wastewater treatment plant effluent discharge to the South Platte River, Colorado, USA

Previous studies have detected numerous organic contaminants and in vitro bioactivities in surface water from the South Platte River near Denver, Colorado, USA. To evaluate the temporal and spatial distribution of selected contaminants of emerging concern, water samples were collected throughout 2018 and 2019 at 11 sites within the S. Platte River and surrounding tributaries with varying proximities to a major wastewater treatment plant (WWTP). Water samples were analyzed for pharmaceuticals, pesticides, steroid hormones, and wastewater indicators and screened for in vitro biological activities. Multiplexed, in vitro assays that simultaneously screen for agonistic activity against 24 human nuclear receptors detected estrogen receptor (ER), peroxisome proliferator activated receptor-gamma (PPARγ), and glucocorticoid receptor (GR) bioactivities in water samples near the WWTP outflow. Targeted in vitro bioassays assessing ER, GR, and PPARγ agonism corroborated bioactivities for ER (up to 55 ± 9.7 ng/L 17β-estradiol equivalents) and GR (up to 156 ± 28 ng/L dexamethasone equivalents), while PPARγ activity was not confirmed. To evaluate the potential in vivo significance of the bioactive contaminants, sexually-mature fathead minnows were caged at six locations upstream and downstream of the WWTP for 5 days after which targeted gene expression analyses were performed. Significant up-regulation of male hepatic vitellogenin was observed at sites with corresponding in vitro ER activity. No site-related differences in GR-related transcript abundance were detected in female adipose or male livers, suggesting observed environmental concentrations of GR-active contaminants do not induce a detectable in vivo response. In line with the lack of detectable targeted in vitro PPARɣ activity, there were no significant effects on PPARɣ-related gene expression. Although the chemicals responsible for GR and PPAR-mediated bioactivities are unknown, results from the present study provide insights into the significance (or lack thereof) of these bioactivities relative to short-term in situ fish exposures.

Environmental Pollution↗

USGS2004

Estimating aboveground biomass of broadleaved woody plants in the understory of Florida Keys pine forests

Species-specific allometric equations that provide estimates of biomass from measured plant attributes are currently unavailable for shrubs common to South Florida pine rocklands, where fire plays an important part in shaping the structure and function of ecosystems. We developed equations to estimate total aboveground biomass and fine fuel of 10 common hardwood species in the shrub layer of pine forests of the lower Florida Keys. Many equations that related biomass categories to crown area and height were significant (p < 0.05), but the form and variables comprising the best model varied among species. We applied the best-fit regression models to structural information from the shrub stratum in 18 plots on Big Pine Key, the most extensive pine forest in the Keys. Estimates based on species-specific equations indicated clearly that total aboveground shrub biomass and shrub fine fuel increased with time since last fire, but the relationships were non-linear. The relative proportion of biomass constituted by the major species also varied with stand age. Estimates based on mixed-species regressions differed slightly from estimates based on species-specific models, but the former could provide useful approximations in similar forests where species-specific regressions are not yet available. ?? 2004 Elsevier B.V. All rights reserved.

Forest Ecology and Management↗

USGS2007

Landscape scale controls on the vascular plant component of dissolved organic carbon across a freshwater delta

Lignin phenol concentrations and compositions were determined on dissolved organic carbon (DOC) extracts (XAD resins) within the Sacramento-San Joaquin River Delta (the Delta), the tidal freshwater portion of the San Francisco Bay Estuary, located in central California, USA. Fourteen stations were sampled, including the following habitats and land-use types: wetland, riverine, channelized waterway, open water, and island drains. Stations were sampled approximately seasonally from December, 1999 through May, 2001. DOC concentrations ranged from 1.3 mg L -1 within the Sacramento River to 39.9 mg L -1 at the outfall from an island drain (median 3.0 mg L -1 ), while lignin concentrations ranged from 3.0 μL -1 within the Sacramento River to 111 μL -1 at the outfall from an island drain (median 11.6 μL -1 ). Both DOC and lignin concentrations varied significantly among habitat/land-use types and among sampling stations. Carbon-normalized lignin yields ranged from 0.07 mg (100 mg OC) -1 at an island drain to 0.84 mg (100 mg OC) -1 for a wetland (median 0.36 mg (100 mg OC) -1 ), and also varied significantly among habitat/land-use types. A simple mass balance model indicated that the Delta acted as a source of lignin during late autumn through spring (10-83% increase) and a sink for lignin during summer and autumn (13-39% decrease). Endmember mixing models using S:V and C:V signatures of landscape scale features indicated strong temporal variation in sources of DOC export from the Delta, with riverine source signatures responsible for 50% of DOC in summer and winter, wetland signatures responsible for 40% of DOC in summer, winter, and late autumn, and island drains responsible for 40% of exported DOC in late autumn. A significant negative correlation was observed between carbon-normalized lignin yields and DOC bioavailability in two of the 14 sampling stations. This study is, to our knowledge, the first to describe organic vascular plant DOC sources at the level of localized landscape features, and is also the first to indicate a significant negative correlation between lignin and DOC bioavailability within environmental samples. Based upon observed trends: (1) Delta features exhibit significant spatial variability in organic chemical composition, and (2) localized Delta features appear to exert strong controls on terrigenous DOC as it passes through the Delta and is exported into the Pacific Ocean.

California↗

USGS2020

Acute toxicity of the lampricides TFM and niclosamide: Effects on a vascular plant and a chironomid species

The lampricides 3-trifluoromethyl-4-nitrophenol (TFM) and niclosamide have been used for about 60 years to control sea lamprey (Petromyzon marinus) in the Great Lakes Basin and Lake Champlain. To register these chemicals as pesticides in North America, their environmental effects must be reviewed on a periodic basis. As a part of this effort, toxicity of TFM and niclosamide to duckweed (Lemna gibba), and of niclosamide to aquatic midge (Chironomus tentans), was assessed. Results of these studies suggest that for both lampricides, the no-observable and lowest observable effects concentrations (NOEC and LOEC) exceed expected environmental concentrations, with effects only in the highest concentrations tested and the longest exposure times. Duckweed exposed to TFM indicated 7-day LOECs ≥ 4.88 mg/L for average specific growth rate and yield, with the EC50 > 9.74 mg/L. For duckweed exposed to niclosamide, 7-day LOECs for average specific growth rate and yield ranged from 0.271 to 0.569 mg/L, with the IC50 0.725 mg/L or greater depending on the parameter measured. For midge larvae exposed to niclosamide-dosed sediment, the LOEC values based on survival and growth were 26.2 mg/kg and > 82.1 mg/kg, respectively, and the EC50 based on survival was 49.6 mg/kg. Based on these data, deleterious effects on aquatic plants and benthic invertebrates are unlikely to result from use of TFM and niclosamide for lamprey control, given that the effect concentrations are in excess of the expected environmental concentrations.

Great Lakes Basin, Lake Champlain↗

USGS2012

Occurrence of triclosan, triclocarban, and its lesser chlorinated congeners in Minnesota freshwater sediments collected near wastewater treatment plants

The antimicrobial agents triclosan (TCS), triclocarban (TCC) and their associated transformation products are of increasing concern as environmental pollutants due to their potential adverse effects on humans and wildlife, including bioaccumulation and endocrine-disrupting activity. Analysis by tandem mass spectrometry of 24 paired freshwater bed sediment samples (top 10 cm) collected by the U.S. Geological Survey near 12 wastewater treatment plants (WWTPs) in Minnesota revealed TCS and TCC concentrations of up to 85 and 822 ng/g dry weight (dw), respectively. Concentrations of TCS and TCC in bed sediments collected downstream of WWTPs were significantly greater than upstream concentrations in 58% and 42% of the sites, respectively. Dichloro- and non-chlorinated carbanilides (DCC and NCC) were detected in sediments collected at all sites at concentrations of up to 160 and 1.1 ng/g dw, respectively. Overall, antimicrobial concentrations were significantly higher in lakes than in rivers and creeks, with relative abundances decreasing from TCC > TCS > DCC > NCC. This is the first statewide report on the occurrence of TCS, TCC and TCC transformation products in freshwater sediments. Moreover, the results suggest biological or chemical TCC dechlorination products to be ubiquitous in freshwater environments of Minnesota, but whether this transformation occurs in the WWTP or bed sediment remains to be determined.

Minnesota↗

USGS2025

An audience segmentation study of native plant gardening behaviors in the United States

Audience segmentation can be used to identify target audiences in environmental public engagement and communication, but few studies have used segmentation to study biodiversity conservation behavior. This study used segmentation to better understand perceptions and behaviors around different types of actions related to native plant gardening. With a United States representative survey ( n = 1,200), we measured beliefs and intentions to engage in personal-sphere (i.e., individual), social diffusion (i.e., encouraging others to act), and civic action behavior (e.g., voting). A latent class analysis (LCA) revealed four distinct groups within the population: Disengaged, Potential Adopters, Potential Amplifiers, and Potential Advocates. Each class comprised approximately one-quarter of the United States population. We found that certain groups are more receptive to personal-sphere behavior, while others may be more receptive to social diffusion behavior or civic action behavior. The groups varied by key distinguishing characteristics: perceptions around civic action, previous personal-sphere and social diffusion behavior, and intentions to engage in personal-sphere action. Findings revealed opportunities to create tailored public engagement strategies to engage different groups in urban biodiversity conservation behavior.

Landscape and Urban Planning↗

USGS2011

A probabilistic seismic risk assessment procedure for nuclear power plants: (II) Application

This paper presents the procedures and results of intensity- and time-based seismic risk assessments of a sample nuclear power plant (NPP) to demonstrate the risk-assessment methodology proposed in its companion paper. The intensity-based assessments include three sets of sensitivity studies to identify the impact of the following factors on the seismic vulnerability of the sample NPP, namely: (1) the description of fragility curves for primary and secondary components of NPPs, (2) the number of simulations of NPP response required for risk assessment, and (3) the correlation in responses between NPP components. The time-based assessment is performed as a series of intensity-based assessments. The studies illustrate the utility of the response-based fragility curves and the inclusion of the correlation in the responses of NPP components directly in the risk computation. ?? 2011 Published by Elsevier B.V.

Conference Paper↗

USGS2011

A probabilistic seismic risk assessment procedure for nuclear power plants: (I) Methodology

A new procedure for probabilistic seismic risk assessment of nuclear power plants (NPPs) is proposed. This procedure modifies the current procedures using tools developed recently for performance-based earthquake engineering of buildings. The proposed procedure uses (a) response-based fragility curves to represent the capacity of structural and nonstructural components of NPPs, (b) nonlinear response-history analysis to characterize the demands on those components, and (c) Monte Carlo simulations to determine the damage state of the components. The use of response-rather than ground-motion-based fragility curves enables the curves to be independent of seismic hazard and closely related to component capacity. The use of Monte Carlo procedure enables the correlation in the responses of components to be directly included in the risk assessment. An example of the methodology is presented in a companion paper to demonstrate its use and provide the technical basis for aspects of the methodology.

Nuclear Engineering and Design↗

USGS2014

A deglacial and Holocene record of climate variability in south-central Alaska from stable oxygen isotopes and plant macrofossils in peat

We used stable oxygen isotopes derived from bulk peat (δ 18 O TOM ), in conjunction with plant macrofossils and previously published carbon accumulation records, in a &sim;14,500 cal yr BP peat core (HT Fen) from the Kenai lowlands in south-central Alaska to reconstruct the climate history of the area. We find that patterns are broadly consistent with those from lacustrine records across the region, and agree with the interpretation that major shifts in δ 18 O TOM values indicate changes in strength and position of the Aleutian Low (AL), a semi-permanent low-pressure cell that delivers winter moisture to the region. We find decreased strength or a more westerly position of the AL (relatively higher δ 18 O TOM values) during the Bølling-Allerød, Holocene Thermal Maximum (HTM), and late Holocene, which also correspond to warmer climate regimes. These intervals coincide with greater peat preservation and enhanced carbon (C) accumulation rates at the HT Fen and with peatland expansion across Alaska. The HTM in particular may have experienced greater summer precipitation as a result of an enhanced Pacific subtropical high, a pattern consistent with modern δ 18 O values for summer precipitation. The combined warm summer temperatures and greater summer precipitation helped promote the observed rapid peat accumulation. A strengthened AL (relatively lower δ 18 O TOM values) is most evident during the Younger Dryas, Neoglaciation, and the Little Ice Age, consistent with lower peat preservation and C accumulation at the HT Fen, suggesting less precipitation reaches the leeward side of the Kenai Mountains during periods of enhanced AL strength. The peatlands on the Kenai Peninsula thrive when the AL is weak and the contribution of summer precipitation is higher, highlighting the importance of precipitation seasonality in promoting peat accumulation. This study demonstrates that δ 18 O TOM values in peat can be applied toward understand large-scale shifts in atmospheric circulation over millennial timescales.

Alaska↗

USGS2015

Rangeland monitoring reveals long-term plant responses to precipitation and grazing at the landscape scale

Managers of rangeland ecosystems require methods to track the condition of natural resources over large areas and long periods of time as they confront climate change and land use intensification. We demonstrate how rangeland monitoring results can be synthesized using ecological site concepts to understand how climate, site factors, and management actions affect long-term vegetation dynamics at the landscape-scale. Forty-six years of rangeland monitoring conducted by the Bureau of Land Management (BLM) on the Colorado Plateau reveals variable responses of plant species cover to cool-season precipitation, land type (ecological site groups), and grazing intensity. Dominant C 3 perennial grasses (Achnatherum hymenoides , Hesperostipa comata) , which are essential to support wildlife and livestock on the Colorado Plateau, had responses to cool-season precipitation that were at least twice as large as the dominant C 4 perennial grass (Pleuraphis jamesii) and woody vegetation. However, these C 3 perennial grass responses to precipitation were reduced by nearly one-third on grassland ecological sites with fine- rather than coarse-textured soils, and there were no detectable C 3 perennial grass responses to precipitation on ecological sites dominated by a dense-growing shrub, Coleogyne ramosissima . Heavy grazing intensity further reduced the responses of C 3 perennial grasses to cool-season precipitation on ecological sites with coarse-textured soils and surprisingly reduced the responses of shrubs as well. By using ecological site groups to assess rangeland condition, we were able to improve our understanding of the long-term relationships between vegetation change and climate, land use, and site characteristics, which has important implications for developing landscape-scale monitoring strategies.

Arizona, Colorado, New Mexico, Utah↗

USGS2007

Mapping an invasive plant, Phragmites australis, in coastal wetlands using the EO-1 Hyperion hyperspectral sensor

Mapping tools are needed to document the location and extent of Phragmites australis, a tall grass that invades coastal marshes throughout North America, displacing native plant species and degrading wetland habitat. Mapping Phragmites is particularly challenging in the freshwater Great Lakes coastal wetlands due to dynamic lake levels and vegetation diversity. We tested the applicability of Hyperion hyperspectral satellite imagery for mapping Phragmites in wetlands of the west coast of Green Bay in Wisconsin, U.S.A. A reference spectrum created using Hyperion data from several pure Phragmites stands within the image was used with a Spectral Correlation Mapper (SCM) algorithm to create a raster map with values ranging from 0 to 1, where 0 represented the greatest similarity between the reference spectrum and the image spectrum and 1 the least similarity. The final two-class thematic classification predicted monodominant Phragmites covering 3.4% of the study area. Most of this was concentrated in long linear features parallel to the Green Bay shoreline, particularly in areas that had been under water only six years earlier when lake levels were 66??cm higher. An error matrix using spring 2005 field validation points (n = 129) showed good overall accuracy-81.4%. The small size and linear arrangement of Phragmites stands was less than optimal relative to the sensor resolution, and Hyperion's 30??m resolution captured few if any pure pixels. Contemporary Phragmites maps prepared with Hyperion imagery would provide wetland managers with a tool that they currently lack, which could aid attempts to stem the spread of this invasive species. ?? 2006 Elsevier Inc. All rights reserved.

Remote Sensing of Environment↗

USGS2010

Identification of plant species by using high spatial and spectral resolution thermal infrared (8.0–13.5 μm) imagery

High spatial and spectral resolution thermal infrared imagery (8.0–13.5 μm) from the SEBASS airborne sensor was used to analyze and map tree canopy spectral features at the State Arboretum of Virginia, near Boyce, Virginia. Fifty tree species were analyzed and about half were directly identified with varying degrees of success on the basis of spectral matched filtering that utilized laboratory-measured leaf spectra as the target signatures. Spectral averages of pixels extracted from SEBASS emissivity data compared favorably with laboratory spectra of leaves collected from individual tree species. Best results were obtained from species having relatively strong spectral contrast, wide and flat leaves, closed planophile canopies, and/or large canopy areas. Tree species having small leaves or unfavorable leaf orientations showed spectral attenuation likely resulting from cavity blackbody effects. Increased spatial resolution and better image calibration and atmospheric correction might lead to further improvements in thermal infrared plant species identification.

Remote Sensing of the Environment↗

USGS2024

Predicting the effects of solar energy development on plants and wildlife in the Desert Southwest, United States

Utility-scale solar energy (USSE) is rapidly expanding and expected to compose the largest source of renewable-generated electricity in the United States and globally over the coming decades. Lands in the hot Desert Southwest (Chihuahuan, Mojave, Sonoran, and San Joaquin Deserts) are increasingly selected for USSE development because of their high solar irradiance. The Desert Southwest supports high biodiversity and provides many ecosystem services but is vulnerable to USSE disturbance and simultaneous stress from aridification and other growing land-use pressures. In this review, a framework is presented for predicting the effects of USSE development on plants and wildlife by linking disturbance types associated with USSE construction and operation to the traits and response strategies of species and guilds. Case studies from representative Desert Southwest species and guilds of conservation concern are used to: review known effects of USSE, predict unknown effects with the trait-based framework, and discuss mitigation strategies. This framework predicts that species with trait plasticity and broad ecological niches will be capable of exploiting USSE development, while species with specific habitat requirements and narrow niches will be more vulnerable. Opportunities for mitigation during development and operation that may lessen these effects are identified. This work is intended to inform USSE management decision-making and long-term planning, as well as encourage new research to test predicted effects and responses.

Renewable & Sustainable Energy Reviews (RSER)↗

USGS2013

Occurrence and partitioning of antibiotic compounds found in the water column and bottom sediments from a stream receiving two wastewater treatment plant effluents in northern New Jersey, 2008.

An urban watershed in northern New Jersey was studied to determine the presence of four classes of antibiotic compounds (macrolides, fluoroquinolones, sulfonamides, and tetracyclines) and six degradates in the water column and bottom sediments upstream and downstream from the discharges of two wastewater treatment plants (WWTPs) and a drinking-water intake (DWI). Many antibiotic compounds in the four classes not removed by conventional WWTPs enter receiving waters and partition to stream sediments. Samples were collected at nine sampling locations on 2 days in September 2008. Two of the nine sampling locations were background sites upstream from two WWTP discharges on Hohokus Brook. Another background site was located upstream from a DWI on the Saddle River above the confluence with Hohokus Brook. Because there is a weir downstream of the confluence of Hohokus Brook and Saddle River, the DWI receives water from Hohokus Brook at low stream flows. Eight antibiotic compounds (azithromycin (maximum concentration 0.24 μg/L), ciprofloxacin (0.08 μg/L), enrofloxacin (0.015 μg/L), erythromycin (0.024 μg/L), ofloxacin (0.92 μg/L), sulfamethazine (0.018 μg/L), sulfamethoxazole (0.25 μg/L), and trimethoprim (0.14 μg/L)) and a degradate (erythromycin-H2O (0.84 μg/L)) were detected in the water samples from the sites downstream from the WWTP discharges. The concentrations of six of the eight detected compounds and the detected degradate compound decreased with increasing distance downstream from the WWTP discharges. Azithromycin, ciprofloxacin, ofloxacin, and trimethoprim were detected in stream-bottom sediments. The concentrations of three of the four compounds detected in sediments were highest at a sampling site located downstream from the WWTP discharges. Trimethoprim was detected in the sediments from a background site. Pseudo-partition coefficients normalized for streambed sediment organic carbon concentration were calculated for azithromycin, ciprofloxacin, and ofloxacin. Generally, there was good agreement between the decreasing order of the pseudo-partition coefficients in this study and the order reported in the literature.

New Jersey↗

USGS2015

Endocrine disrupting alkylphenolic chemicals and other contaminants in wastewater treatment plant effluents, urban streams, and fish in the Great Lakes and Upper Mississippi River Regions

Urban streams are an integral part of the municipal water cycle and provide a point of discharge for wastewater treatment plant (WWTP) effluents, allowing additional attenuation through dilution and transformation processes, as well as a conduit for transporting contaminants to downstream water supplies. Domestic and commercial activities dispose of wastes down-the-drain, resulting in wastewater containing complex chemical mixtures that are only partially removed during treatment. A key issue associated with WWTP effluent discharge into streams is the potential to cause endocrine disruption in fish. This study provides a long-term (1999-2009) evaluation of the occurrence of alkylphenolic endocrine disrupting chemicals (EDCs) and other contaminants discharged from WWTPs into streams in the Great Lakes and Upper Mississippi River Regions (Indiana, Illinois, Michigan, Minnesota, and Ohio). The Greater Metropolitan Chicago Area Waterways, Illinois, were evaluated to determine contaminant concentrations in the major WWTP effluents and receiving streams, and assess the behavior of EDCs from their sources within the sewer collection system, through the major treatment unit processes at a WWTP, to their persistence and transport in the receiving stream. Water samples were analyzed for alkylphenolic EDCs and other contaminants, including 4-nonylphenol (NP), 4-nonylphenolpolyethoxylates (NPEO), 4-nonylphenolethoxycarboxylic acids (NPEC), 4-tert-octylphenol (OP), 4-tert-octylphenolpolyethoxylates (OPEO), bisphenol A, triclosan, ethylenediaminetetraacetic acid (EDTA), and trace elements. All of the compounds were detected in all of the WWTP effluents, with EDTA and NPEC having the greatest concentrations. The compounds also were detected in the WWTP effluent dominated rivers. Multiple fish species were collected from river and lake sites and analyzed for NP, NPEO, NPEC, OP, and OPEO. Whole-body fish tissue analysis indicated widespread occurrence of alkylphenolic compounds, with the highest concentrations occurring in streams with the greatest WWTP effluent content. Biomarkers of endocrine disruption in the fish indicated long-term exposure to estrogenic chemicals in the wastewater impacted urban waterways.

Science of the Total Environment↗

USGS2016

Microbial pathogens in source and treated waters from drinking water treatment plants in the United States and implications for human health

An occurrence survey was conducted on selected pathogens in source and treated drinking water collected from 25 drinking water treatment plants (DWTPs) in the United States. Water samples were analyzed for the protozoa Giardia and Cryptosporidium (EPA Method 1623); the fungi Aspergillus fumigatus , Aspergillus niger and Aspergillus terreus (quantitative PCR [qPCR]); and the bacteria Legionella pneumophila (qPCR), Mycobacterium avium , M. avium subspecies paratuberculosis , and Mycobacterium intracellulare (qPCR and culture). Cryptosporidium and Giardia were detected in 25% and in 46% of the source water samples, respectively (treated waters were not tested). Aspergillus fumigatus was the most commonly detected fungus in source waters (48%) but none of the three fungi were detected in treated water. Legionella pneumophila was detected in 25% of the source water samples but in only 4% of treated water samples. M. avium and M. intracellulare were both detected in 25% of source water, while all three mycobacteria were detected in 36% of treated water samples. Five species of mycobacteria, Mycobacterium mucogenicum , Mycobacterium phocaicum , Mycobacterium triplex , Mycobacterium fortuitum , and Mycobacterium lentiflavum were cultured from treated water samples. Although these DWTPs represent a fraction of those in the U.S., the results suggest that many of these pathogens are widespread in source waters but that treatment is generally effective in reducing them to below detection limits. The one exception is the mycobacteria, which were commonly detected in treated water, even when not detected in source waters.

Science of the Total Environment↗

USGS2020

Concentrations and size distribution of TiO2 and Ag engineered particles in five wastewater treatment plants in the United States

The growing use of engineered particles ( e.g. , nanosized and pigment sized particles, 1 to 100 nm and 100 to 300 nm, respectively) in a variety of consumer products increases the likelihood of their release into the environment. Wastewater treatment plants (WWTPs) are an important pathways of introduction of engineered particles to the aquatic systems. This study reports the concentrations, removal efficiencies, and particle size distributions of Ag and TiO 2 engineered particles in five WWTPs in three states in the United States. The concentration of Ag engineered particles was quantified as the total Ag concentration, whereas the concentration of TiO 2 engineered particles was quantified using mass-balance calculations and shifts in the elemental ratio of Ti/Nb above their natural background elemental ratio. Ratios of Ti/Nb in all WWTP influents, activated sludges, and effluents were 2–12 times higher ( e.g. , 519 to 3243) than the natural background Ti/Nb ratio ( e.g. , 267 ± 9), indicating that 49–92% of Ti originates from anthropogenic sources. The concentration of TiO 2 engineered particles (in μg TiO 2 L −1 ) in the influent, activated sludge, and effluent varied within the ranges of 70–670, 3570–6700, and 7–30, respectively. The concentration of Ag engineered particles (in μg Ag L −1 ) in the influent, activated sludge, and effluent varied within the ranges of 0.11–0.33, 1.45–1.65, and 0.01–0.04, respectively. The overall removal efficiency ( e.g. , effluent/influent concentrations) of TiO 2 engineered particles ( e.g. , 90 to 96%) was higher than that for Ag engineered particles ( e.g. , 82 to 95%). Particles entering WWTPs are in the nanosized range for Ag ( e.g. , >99%) and a mixture of nanosized ( e.g. , 15 to 90%) and pigment sized particles ( e.g. , 10 to 85%) for TiO 2 . Nearly all Ag (>99%) and 55 to 100% of TiO 2 particles discharged to surface water with WWTP effluent are within the nanosize range. This study provides evidence that TiO 2 and Ag engineered nanomaterials enter aquatic systems with WWTP effluents, and that their concentrations are expected to increase with the increased applications of TiO 2 and Ag engineered nanomaterials in consumer products.

California, Massachusetts, South Carolina↗