Influence of tobacco product wastes in a protected coastal reserve adjacent to urbanization.

The present study, conducted at the Kendall-Frost Mission Bay Marsh Reserve in San Diego, California, aimed to assess tobacco-related pollutants in urban waters, a topic with limited prior research. Across 26 events occurring between November 2019 and February 2022, encompassing both wet and dry seasons at two outfall sites (Noyes St. and Olney St.), water and sediment samples were subjected to analysis for nicotine and cotinine levels, with Noyes St. displaying wide variation in nicotine concentrations, reaching a peak of 50.75 ng/L in water samples, whereas Olney St. recorded a peak of 1.46 ng/L. Wet seasons consistently had higher nicotine levels in water, suggesting the possibility of tobacco litter entering the reserve through stormwater runoff. Cotinine was detected in both sites in both water and sediment samples; however, these levels were considerably lower in comparison to nicotine concentrations. Limited research assesses aquatic environmental pollution from tobacco use and disposal, especially in protected areas like urban natural reserves. This study was conducted at the Kendall-Frost Mission Bay Marsh Reserve in San Diego, California, to evaluate tobacco-related pollutants in San Diego's urban waters. Twenty-six sampling events between November 2019 and February 2022, spanning wet and dry seasons at two outfall sites, were conducted. Nicotine and cotinine, a major ingredient of tobacco and its metabolite, were analyzed in the collected water and sediment samples. Nicotine concentrations differed substantially between the outfall locations (Noyes St. and Olney St.), with Noyes St. displaying wide variations, averaging at 9.31 (±13.24) ng/L with a maximum concentration of 50.75 ng/L, and Olney St. at 0.53 (±0.41) ng/L with a maximum concentration of 1.46 ng/L in water samples. In both locations, the nicotine concentrations in water samples were higher during wet seasons than dry seasons, and this pattern was more significant at Noyes St. outfall than at Olney St. outfall, which received not only stormwater runoff but also was connected to Mission Bay. Although this pattern did not directly align with sediment nicotine levels at both sites, maximum nicotine concentration in Noyes St. sediments during wet seasons was approximately 120 times higher than in Olney St. sediments. Regarding cotinine, Noyes St. outfall water averaged 3.17 ng/L (±1.88), and Olney St. water averaged 1.09 ng/L (±1.06). Similar to nicotine, the cotinine concentrations were higher in Noyes St. water and sediment compared to Olney St., but overall, the cotinine concentrations in both water and sediment were much lower than the corresponding nicotine concentrations. The study identifies urban stormwater runoff as a potential source of nicotine and cotinine pollution in a protected reserve, implicating tobacco product litter and human tobacco use as contributing factors.

Modeled and measured SARS-CoV-2 virus in septic tank systems for wastewater surveillance.

SARS-CoV-2 wastewater surveillance (WWS) at wastewater treatment plants (WWTPs) can reveal sewered community COVID-19 prevalence. For unsewered areas using septic tank systems (STSs) or holding tanks, how to conduct WWS remains unexplored. Here, two large STSs serving Zuma Beach (Malibu, CA) were studied. Supernatant and sludge SARS-CoV-2 concentrations from the directly-sampled STSs parameterized a dynamic solid-liquid separation, mass balance-based model for estimating the infection rate of users. Pumped septage before hauling and upon WWTP disposal was also sampled and assessed. Most (96%) STS sludge samples contained SARS-CoV-2 N1 and N2 genes, with concentrations exceeding the supernatant and increasing with depth while correlating with total suspended solids (TSS). The trucked septage contained N1 and N2 genes which decayed (coefficients: 0.09-0.29 h-1) but remained detectable. Over approximately 5 months starting in December 2020, modeled COVID-19 prevalence estimations among users ranged from 8 to 18%, mirroring a larger metropolitan area for the first 2 months. The approaches herein can inform public health intervention and augment conventional WWS in that: (1) user infection rates for communal holding tanks are estimable and (2) pumped and hauled septage can be assayed to infer where disease is spreading in unsewered areas.

Municipal separate storm sewer system (MS4) dry weather flows and potential flow sources as assessed by conventional and advanced bacterial analyses.

Municipal separate storm sewer systems (MS4s) function in urbanized areas to convey flows during both wet weather (i.e., stormwater) and dry weather (i.e., urban runoff as well as subsurface sources of flow) to receiving waters. While urban stormwater is known to contain microbial and chemical pollutants, MS4 dry weather flows, or non-stormwater discharges (NSWDs), are much less studied, although they are also known to contain pollutants, especially when these flows include raw sewage. In addition, some natural NSWDs (e.g., from groundwater infiltrating MS4 pipes) are critical for aquatic habitat protection. Thus, it is important to distinguish NSWD sources to prevent non-natural flows while retaining natural waters (i.e., groundwater). Here, MS4 dry weather flows were assessed by analyzing water samples from MS4 outfalls across multiple watersheds and water provider service areas in south Orange County, CA; potential NSWD sources including sewage, recycled water, potable water, and groundwater were sampled and analyzed for their likely contributions to overall NSWDs. Geochemical and microbiological water quality indicators, as well as bacterial communities, differed across NSWDs, yet water quality within most locations did not vary significantly diurnally or by sampling date. Meanwhile, NSWD source waters had distinctly different bacterial taxa abundances and specific bacterial genera. Shared geochemical and microbial characteristics of certain sources and outfall flows suggested the contributions of sources to outfall flows. The average proportions by sources contributing to MS4 outfalls were further estimated by SourceTracker and FEAST, respectively. The results of this study highlight the use of multiple tools when assessing chemical and microbiological water quality to predict sources of NSWDs contributing to urban MS4 flows during dry weather. This information can be used to support management actions to reduce unnatural and high risk sources of dry weather drainage while preserving natural sources important to environmental health in downstream receiving waters.

Aging of Copper Nanoparticles in the Marine Environment Regulates Toxicity for a Coastal Phytoplankton Species.

Environmental conditions in aquatic ecosystems transform toxic chemicals over time, influencing their bioavailability and toxicity. Using an environmentally relevant methodology, we tested how exposure to seawater for 1-15 weeks influenced the accumulation and toxicity of copper nanoparticles (nano-Cu) in a marine phytoplankton species. Nano-Cu rapidly agglomerated in seawater and then decreased in size due to Cu dissolution. Dissolution rates declined during weeks 1-4 and remained low until 15 weeks, when the large agglomerates that had formed began to rapidly dissolve again. Marine phytoplankton species were exposed for 5-day periods to nano-Cu aged from 1 to 15 weeks at concentrations from 0.01 to 20 ppm. Toxicity to phytoplankton, measured as change in population growth rate, decreased significantly with particle aging from 0 to 4 weeks but increased substantially in the 15-week treatment due apparently to elevated Cu dissolution of reagglomerated particles. Results indicate that the transformation, fate, and toxicity of nano-Cu in marine ecosystems are influenced by a highly dynamic physicochemical aging process.

Stormwater biofilter response to high nitrogen loading under transient flow conditions: Ammonium and nitrate fates, and nitrous oxide emissions.

Nitrogen (N) in urban runoff is often treated with green infrastructure including biofilters. However, N fates across biofilters are insufficiently understood because prior studies emphasize low N loading under laboratory conditions, or use "steady-state" flow regimes over short time scales. Here, we tested field scale biofilter N fates during simulated storms delivering realistic transient flows with high N loading. Biofilter outflow ammonium (NH4+-N) was 60.7 to 92.3% lower than that of the inflow. Yet the characteristic times for nitrification (days to weeks) and denitrification (days) relative to N residence times (7 to 30 h) suggested low N transformation across the biofilters. Still, across 7 successive storms, total outflow nitrate (NO3--N) greatly exceeded (3100 to 3900%) inflow nitrate, a result only explainable by biofilter soil N nitrification occurring between storms. Archaeal, and bacterial amoA gene copies (2.1 × 105 to 1.2 × 106 gc g soil-1), nitrifier presence by16S rRNA gene sequencing, and outflow δ18O-NO3- values (-3.0 to 17.1 ‰) reinforced that nitrification was occurring. A ratio of δ18O-NO3- to δ15N-NO3- of 1.83 for soil eluates indicated additional processes: N assimilation, and N mineralization. Denitrification potential was suggested by enzyme activities and soil denitrifying gene copies (nirK + nirS: 3.0 × 106 to 1.8 × 107; nosZ: 5.0 × 105 to 2.2 × 106 gc g soil-1). However, nitrous oxide (N2O-N) emissions (13.5 to 84.3 µg N m - 2 h - 1) and N2O export (0.014 g N) were low, and soil nitrification enzyme activities (0.45 to 1.63 mg N kg soil-1day-1) exceeded those for denitrification (0.17 to 0.49 mg N kg soil-1 day-1). Taken together, chemical, bacterial, and isotopic metrics evidenced that storm inflow NH4+sorbs and, along with mineralized soil N, nitrifies during biofilter dry-down; little denitrification and associated N2O emissions ensue, and thus subsequent storms export copious NO3--N. As such, pulsed pass-through biofilters require redesign to promote plant assimilation and/or denitrification of mineralized and nitrified N, to minimize NO3--N generation and export.

Assessing multiple fecal sources to surf zone waters of two recreational beaches by bacterial community analysis.

Fecal sources to recreational surf zone waters should be identified to protect public health. While watershed origins of human and other fecal sources are often discoverable by quantitative polymerase chain reaction (qPCR) of fecal markers using spatially stratified samples, similarly assessing wastewater treatment plant (WWTP) outfall and other offshore contributions to surf zones is challenged by individual marker fate and transport. Here, bacterial communities were assessed for relatedness between all hypothesized fecal sources and surf zone waters for two urban California recreational beaches, by sequencing genes encoding 16S rRNA and analyzing data using SourceTracker and FEAST. Ambient marine bacterial communities dominated the surf zone, while fecal (human, dog, or gull) or wastewater (sewage or treated WWTP effluent) bacterial communities were present at low proportions and those from recycled water were absent. Based on the relative abundances of bacterial genera specifically associated with human feces, the abundances of HF183 in bacterial community sequences, and FEAST and SourceTracker results when benchmarked to HF183, the major sources of HF183 to surf zone waters were human feces and treated WWTP effluent. While surf zone sequence proportions from human sources (feces, sewage and treated WWTP effluent) appeared uncorrelated to previously obtained qPCR HF183 results, the proportions of human fecal and potential human pathogen sequences in surf zone waters were elevated when there were more swimmers (i.e. during weekday afternoons, holidays and busy weekends, and race events), thus confirming previously-published qPCR-based conclusions that bather shedding contributed low levels of human fecal contamination. Here, bacterial community sequencing also showed evidence that treated WWTP effluent from an offshore outfall was entering the surf zone, thereby resolving a prior uncertainty. Thus, bacterial community sequencing not only confirms qPCR HF183-based human marker detections, but further allows for confirming fecal sources for which individual marker quantification results can be equivocal.

Highly variable removal of pathogens, antibiotic resistance genes, conventional fecal indicators and human-associated fecal source markers in a pilot-scale stormwater biofilter operated under realistic stormflow conditions.

Green stormwater infrastructure systems, such as biofilters, provide many water quality and other environmental benefits, but their ability to remove human pathogens and antibiotic resistance genes (ARGs) from stormwater runoff is not well documented. In this study, a field scale biofilter in Southern California (USA) was simultaneously evaluated for the breakthrough of a conservative tracer (bromide), conventional fecal indicators, bacterial and viral human-associated fecal source markers (HF183, crAssphage, and PMMoV), ARGs, and bacterial and viral pathogens. When challenged with a 50:50 mixture of untreated sewage and stormwater (to mimic highly contaminated storm flow) the biofilter significantly removed (p < 0.05) 14 of 17 microbial markers and ARGsin descending order of concentration reduction: ermB (2.5 log(base 10) reduction) > Salmonella (2.3) > adenovirus (1.9) > coliphage (1.5) > crAssphage (1.2) > E. coli (1.0) ∼ 16S rRNA genes (1.0) ∼ fecal coliform (1.0) ∼ intl1 (1.0) > Enterococcus (0.9) ∼ MRSA (0.9) ∼ sul1 (0.9) > PMMoV (0.7) > Entero1A (0.5). No significant removal was observed for GenBac3, Campylobacter, and HF183. From the bromide data, we infer that 0.5 log-units of attenuation can be attributed to the dilution of incoming stormwater with water stored in the biofilter; removal above this threshold is presumably associated with non-conservative processes, such as physicochemical filtration, die-off, and predation. Our study documents high variability (>100-fold) in the removal of different microbial contaminants and ARGs by a field-scale stormwater biofilter operated under transient flow and raises further questions about the utility of human-associated fecal source markers as surrogates for pathogen removal.

Genetic sequence data evidence that human faecal-associated HF183 sequences are on human skin and in urine.

AIMS: The DNA marker HF183 is a partial 16S rRNA gene sequence highly specific to human-associated Bacteroides including Bacteroides dorei. While HF183 is used to assess human faecal contamination in aquatic environments worldwide, little is known about the existence of HF183 and B. dorei in human microbiomes outside of the human gastrointestinal tract and faeces. METHODS AND RESULTS: Previously published human skin and urine microbiome data sets from five independent human body skin studies, the Human Microbiome Project (HMP) and three independent human urine studies were analysed. The HF183 gene sequence was detected in all skin data sets, with the ratios of positive samples ranging from 0.5% to 36.3%. Popliteal fossa (knee), volar forearm and inguinal (groin) creases were identified as hot spots. HF183 was detected in two of three urine data sets, with ratios of positive samples ranging from 0% to 37.5%. All HF183-containing sequences from these data sets were classified as associated with B. dorei. CONCLUSIONS: HF183 is widespread on human skin and present in urine. SIGNIFICANCE AND IMPACT OF STUDY: Skin and urine microbiomes could be sources of HF183 to environmental waters. Such non-faecal sources of HF183 might explain low concentrations of HF183 in recreational waters when swimmers are present.

Influence of soil characteristics and metal(loid)s on antibiotic resistance genes in green stormwater infrastructure in Southern California.

The synergetic effects of metal(loid)s and soil characteristics on bacterial antibiotic resistance genes (ARGs) in green stormwater infrastructure (GSI) has been relatively understudied. Surface soil samples from six GSIs in Southern California over three time periods were assessed for selected ARGs, class 1 integron-integrase genes (intI1), 16S rRNA genes, and bioavailable and total concentrations of nine metal(loid)s, to investigate the relationships among ARGs, soil characteristics, and co-occurring metal(loid)s. Significant correlations existed among relative gene abundances (sul1, sul2, tetW, and intI1), total metal(loid)s (arsenic, copper, lead, vanadium, and zinc), and bioavailable metal(loid) (arsenic) (r = 0.29-0.61, padj < 0.05). Additionally, soil texture, organic matter, and nutrients within GSI appeared to be significantly correlated with relative gene abundances of sul1, sul2, and tetW (r = -0.57 to 0.59, padj < 0.05). Multiple regression models significantly improved the estimation of ARGs in GSI when considering multiple effects of soil characteristics and metal(loid)s (r = 0.74, padj < 0.001) compared to correlation results. Total arsenic was a significant (positive) correlate in all the regression models of relative gene abundances. This work provides new insights into co-dependencies between GSI ARGs and co-occurring metal(loid)s, indicating the need for risk assessment of metal(loid)-influenced ARG proliferation.

Nano-La2O3 Induces Honeybee (Apis mellifera) Death and Enriches for Pathogens in Honeybee Gut Bacterial Communities.

Honeybees (Apis mellifera) can be exposed via numerous potential pathways to ambient nanoparticles (NPs), including rare earth oxide (REO) NPs that are increasingly used and released into the environment. Gut microorganisms are pivotal in mediating honeybee health, but how REO NPs may affect honeybee health and gut microbiota remains poorly understood. To address this knowledge gap, honeybees were fed pollen and sucrose syrup containing 0, 1, 10, 100, and 1000mgkg-1 of nano-La2O3 for 12days. Nano-La2O3 exerted detrimental effects on honeybee physiology, as reflected by dose-dependent adverse effects of nano-La2O3 on survival, pollen consumption, and body weight (p<0.05). Nano-La2O3 caused the dysbiosis of honeybee gut bacterial communities, as evidenced by the change of gut bacterial community composition, the enrichment of pathogenic Serratia and Frischella, and the alteration of digestion-related taxa Bombella (p<0.05). There were significant correlations between honeybee physiological parameters and the relative abundances of pathogenic Serratia and Frischella (p<0.05), underscoring linkages between honeybee health and gut bacterial communities. Taken together, this study demonstrates that nano-La2O3 can cause detrimental effects on honeybee health, potentially by disordering gut bacterial communities. This study thus reveals a previously overlooked effect of nano-La2O3 on the ecologically and economically important honeybee species Apis mellifera.

SARS-CoV-2 Wastewater Surveillance for Public Health Action.

Wastewater surveillance for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has garnered extensive public attention during the coronavirus disease pandemic as a proposed complement to existing disease surveillance systems. Over the past year, methods for detection and quantification of SARS-CoV-2 viral RNA in untreated sewage have advanced, and concentrations in wastewater have been shown to correlate with trends in reported cases. Despite the promise of wastewater surveillance, for these measurements to translate into useful public health tools, bridging the communication and knowledge gaps between researchers and public health responders is needed. We describe the key uses, barriers, and applicability of SARS-CoV-2 wastewater surveillance for supporting public health decisions and actions, including establishing ethics consideration for monitoring. Although wastewater surveillance to assess community infections is not a new idea, the coronavirus disease pandemic might be the initiating event to make this emerging public health tool a sustainable nationwide surveillance system, provided that these barriers are addressed.

Molecular Mechanisms of Nanomaterial-Bacterial Interactions Revealed by Omics-The Role of Nanomaterial Effect Level.

Nanotechnology is employed across a wide range of antibacterial applications in clinical settings, food, pharmaceutical and textile industries, water treatment and consumer goods. Depending on type and concentration, engineered nanomaterials (ENMs) can also benefit bacteria in myriad contexts including within the human body, in biotechnology, environmental bioremediation, wastewater treatment, and agriculture. However, to realize the full potential of nanotechnology across broad applications, it is necessary to understand conditions and mechanisms of detrimental or beneficial effects of ENMs to bacteria. To study ENM effects, bacterial population growth or viability are commonly assessed. However, such endpoints alone may be insufficiently sensitive to fully probe ENM effects on bacterial physiology. To reveal more thoroughly how bacteria respond to ENMs, molecular-level omics methods such as transcriptomics, proteomics, and metabolomics are required. Because omics methods are increasingly utilized, a body of literature exists from which to synthesize state-of-the-art knowledge. Here we review relevant literature regarding ENM impacts on bacterial cellular pathways obtained by transcriptomic, proteomic, and metabolomic analyses across three growth and viability effect levels: inhibitory, sub-inhibitory or stimulatory. As indicated by our analysis, a wider range of pathways are affected in bacteria at sub-inhibitory vs. inhibitory ENM effect levels, underscoring the importance of ENM exposure concentration in elucidating ENM mechanisms of action and interpreting omics results. In addition, challenges and future research directions of applying omics approaches in studying bacterial-ENM interactions are discussed.

Sources of Low Level Human Fecal Markers in Recreational Waters of Two Santa Barbara, CA Beaches: Roles of WWTP Outfalls and Swimmers.

Worldwide, fecal indicator bacteria (FIB) evidence coastal water contamination for which sources are unknown. Here, for two FIB-impacted Santa Barbara recreational beaches, hypothesized fecal sources were investigated over three dry seasons (summers) using nearly 2000 field samples of water (ocean, creek, groundwater), sand, sediments, effluent and fecal sources. In years 1 and 2, gull and dog feces were identified as the probable main FIB sources to surf zone waters, yet HF183 human fecal markers were consistently detected. Determining HF183 sources was therefore prioritized, via year 3 sub-studies. In lower watersheds, human and dog wastes were mobilized by small storms into creeks, but no storm drain outfalls or creeks discharged into surf zones. Beach area bathrooms, sewers, and a septic system were not sources: dye tracing discounted hydraulic connections, and shallow groundwater was uncontaminated. Sediments from coastal creeks and downstream scour ponds, nearshore marine sediments, and sands from inter- and supratidal zones contained neither HF183 nor pathogens. Two nearby wastewater treatment plant (WWTP) outfalls discharged HF183 into plumes that were either deep or distant with uncertain onshore transport. Regardless, local sources were evidenced, as surf zone HF183 detection rates mostly exceeded those offshore and nearshore (around boat anchorages). The presence of swimmers was associated with surf zone HF183, as swimmer counts (on weekdays, holidays, weekends, and during races) significantly correlated (p<0.05, n = 196) to HF183 detections. Besides comprehensively assessing all possible fecal sources, this study provides new explanations of chronic low-level human markers in recreational beach surf zones, suggesting likely lowest achievable HF183 thresholds.

Bather Shedding as a Source of Human Fecal Markers to a Recreational Beach.

Microbial source tracking (MST) can identify and locate surf zone fecal indicator bacteria (FIB) sources. However, DNA-based fecal marker results may raise new questions, since FIB and DNA marker sources can differ. Here, during 2 years of summertime (dry season) MST for a Goleta, California recreational beach, surf zone FIB were mainly from gulls, yet low level human-associated DNA-based fecal marker (HF183) was detected in 25 and 14% of surf zone water samples, respectively. Watershed sources were hypothesized because dry weather creek waters had elevated FIB, and runoff-generating rain events mobilized human (and dog) fecal markers and Salmonella spp. into creeks, with human marker HF183 detected in 40 and 50% of creek water samples, dog markers detected in 70 and 50% of samples, and Salmonella spp. in 40 and 33.3% of samples, respectively over 2 years. However, the dry weather estuary outlet was bermed in the first study year; simultaneously, creek fecal markers and pathogens were lower or similar to surf zone results. Although the berm breached in the second year, surf zone fecal markers stayed low. Watershed sediments, intertidal beach sands, and nearshore sediments were devoid of HF183 and dog-associated DNA markers. Based on dye tests and groundwater sampling, beach sanitary sewers were not leaking; groundwater was also devoid of HF183. Offshore sources appeared unlikely, since FIB and fecal markers decreased along a spatial gradient from the surf zone toward nearshore and offshore ocean waters. Further, like other regional beaches, surf zone HF183 corresponded significantly to bather counts, especially in the afternoons when there were more swimmers. However, morning detections of surf zone HF183 when there were few swimmers raised the possibility that the wastewater treatment plant (WWTP) offshore outfall discharged HF183 overnight which transported to the surf zone. These findings support that there may be lowest achievable limits of surf zone HF183 owing to several chronic and permanent, perhaps diurnal, low concentration sources.

Limited Bacterial Removal in Full-Scale Stormwater Biofilters as Evidenced by Community Sequencing Analysis.

In urban areas, untreated stormwater runoff can pollute downstream surface waters. To intercept and treat runoff, low-impact or "green infrastructure" approaches such as using biofilters are adopted. Yet, actual biofilter pollutant removal is poorly understood; removal is often studied in laboratory columns, with variable removal of viable and culturable microbial cell numbers including pathogens. Here, to assess bacterial pollutant removal in full-scale planted biofilters, stormwater was applied, unspiked or spiked with untreated sewage, in simulated storm events under transient flow conditions, during which biofilter influents versus effluents were compared. Based on microbial biomass, sequences of bacterial community genes encoding 16S rRNA, and gene copies of the human fecal marker HF183 and of the Enterococcus spp. marker Entero1A, removal of bacterial pollutants in biofilters was limited. Dominant bacterial taxa were similar for influent versus effluent aqueous samples within each inflow treatment of either spiked or unspiked stormwater. Bacterial pollutants in soil were gradually washed out, albeit incompletely, during simulated storm flushing events. In post-storm biofilter soil cores, retained influent bacteria were concentrated in the top layers (0-10 cm), indicating that the removal of bacterial pollutants was spatially limited to surface soils. To the extent that plant-associated processes are responsible for this spatial pattern, treatment performance might be enhanced by biofilter designs that maximize influent contact with the rhizosphere.

Evaluating the relationships between specific drainage area characteristics and soil metal concentrations in long-established bioswales receiving suburban stormwater runoff.

Bioswales are used to attenuate stormwater pollution, but their long-term sustainability regarding sequestered metals is relatively unknown, and a clear rationale for prioritizing soil management is lacking. Impervious areas draining into four 14-year-old suburban bioswales were delineated, for which surface soils (top 10 cm; 72 samples) were sampled; soils from 4 adjacent reference sites were also sampled. Total and water soluble metals (Cd, Cu, Pb, Zn) were quantified, and the relationships between metal concentrations and drainage area characteristics evaluated. Annual metal loads were estimated using regional runoff data to simulate current and future metal concentrations; risks to soil biota were assessed by comparing metal concentrations to ecological screening levels. The drainage areas' percent imperviousness (37-71%) and ratios of impervious drainage area to bioswale area (2.0-5.7) varied, owing to differing proportions of rooftops, paved surfaces, lawns, and natural soils. Total Cu and Zn ranged from 10.0 to 43.2 mg/kg dry soil, and 15.6 to 129.5 mg/kg dry soil, respectively. Across all bioswales, total Zn was positively correlated to percent impervious area (r = 0.32, p = 0.0073), the ratio of connected impervious drainage area to infiltration area (r = 0.32, p = 0.0073), and percent drainage area as paved surfaces (r = 0.46, p = 5.6 E-05), but negatively correlated to percent drainage area as lawns (r = -0.48; p = 2.4 E-05). Water soluble metal concentrations were orders of magnitude lower than total metals. Given annual metal loads (0.2-0.4 mg Cu/kg dry soil; 1.5-3.1 mg Zn/kg dry soil), replacing bioswale soils to constrain metal concentrations would be unnecessary for decades. Taken together, this study proposes a transferable approach of estimating, then verifying via sampling and analysis, bioswale soil metal concentrations, such that soil management decisions can be benchmarked to ecological screening levels.

Evaluation of frameworks proposed as protective of antimicrobial resistance propagation in the environment.

Antimicrobial resistance (AMR) in the environment is a globally concerning issue. This study sought to improve the understanding of human health risks from an environmental AMR proliferation perspective. Surface water concentrations of 11 most used antibiotics in the United States were simulated for the Columbia and Sacramento River watersheds using the Pharmaceutical Assessment and Transport Evaluation (PhATE) model. The predicted environmental concentrations (PECs) and literature-reported measured environmental concentrations (MECs) of antibiotics were compared to the predicted no effect concentrations (PNECs) of three frameworks proposed as protective of AMR selection. For all of the studied antibiotics, PECs (except for moxifloxacin, a 4th generation fluoroquinolone), and at least one published MEC, were above the safe limit proposed by at least one of the three frameworks. The results indicate that a variety of different antibiotics with different mechanisms of action and physico-chemical properties are likely in environmental compartments at or above the concentrations currently proposed as safe from an AMR proliferation perspective. Understanding environmental occurrence of antibiotics is important for assessing environmental exposures and, when compared to PNECs for resistance selection, can-either alone or in combination with other methods- more specifically indicate where there are potential risks of AMR proliferation.

Surf zone microbiological water quality following emergency beach nourishment using sediments from a catastrophic debris flow.

Urban disaster response requires disposal of complex wastes. This study regards a case wherein high intensity rainfall fell over a remote mountainous area previously burned by wildfire, generating debris flows that devastated a downstream town. Sanitary sewers and homes with septic systems were damaged, releasing human waste into the debris flow field. Contaminated sediments, with their high fecal indicator bacteria (FIB) concentrations, were cleared from public rights-of-way and creek channels by local authorities, then disposed onto distant Goleta Beach for beach nourishment, causing immediate surf zone microbiological water quality exceedances. To determine potential public health threats, disposed sediments and surf zone waters were sampled and analyzed-relative to reference samples of mountain soil and raw sewage-for FIB, pathogens, human (HF183) and other host- (Gull2 TaqMan, and DogBact) associated DNA-based fecal markers, and bacterial community 16S rRNA gene sequences. Approximately 20% of disposed sediment samples contained the HF183 marker; sequencing suggested that all samples were contaminated by sewage. In an initial sediment disposal period, surf zone waters harbored intestinal bacterial sequences that were shared with disposed sediments and sewage. Yet surf zone bacterial communities returned to mostly marine clades within weeks. Taken together, multiple conventional and DNA-based analyses informed this forensic assessment of human waste contamination. In the future, similar analyses could be used earlier in disaster response to guide sediment disposal decisions towards continuously protecting beachgoer health.

Towards a better understanding of Pseudomonas putida biofilm formation in the presence of ZnO nanoparticles (NPs): Role of NP concentration.

Elucidating the effects of nanoparticles (NPs) on key bacterial functions not only deepens our understanding of nano-toxicity mechanisms, but also guides us in the design criteria for manufacturing safe nanomaterials. In this study, bacterial growth, biofilm development and the expression of biofilm-related genes were monitored in Pseudomonas putida KT2440, a plant-beneficial bacterium, following exposure to ZnO NPs. Low concentrations of NPs (0.5-30 mg L-1) significantly promoted bacterial growth and biofilm formation, while higher concentrations (>30 mg L-1) significantly inhibited biofilm formation. Confocal laser scanning microscopy revealed that microscope slides coated with 0.5 mg L-1 of ZnO NPs showed enhanced bacterial colonization and biomass production, but at higher concentrations (250 mg L-1), biomass production was about 11 times lower than that of the substrate without NPs. Increased protein and sugar contents of the biofilm matrix corroborated the stimulating effects of low concentrations of ZnO NPs. Physiological data were supported by changes in the expression of genes associated with oxidative stress and biofilm development. ZnO NPs at 0.5 mg L-1 stimulated the expression of quorum sensing, lipopolysaccharide biosynthesis, and antibiotic resistance genes; high concentrations of ZnO NPs (250 mg L-1) down-regulated biofilm formation-related genes and up-regulated antioxidant genes. Our results indicate that long-term release of low concentrations of ZnO NPs to the environment would promote undesired biofilm formation and increased resistance to antibiotics.