Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in urban atmospheres. Several PAHs are known carcinogens or are the precursors to carcinogenic daughter compounds. Understanding the ...contributions of the various emission sources is critical to appropriately managing PAH levels in the environment. The sources of PAHs to ambient air in Baltimore, MD, were determined by using three source apportionment methods, principal component analysis with multiple linear regression, UNMIX, and positive matrix factorization. Determining the source apportionment through multiple techniques mitigates weaknesses in individual methods and strengthens the overlapping conclusions. Overall source contributions compare well among methods. Vehicles, both diesel and gasoline, contribute on average 16−26%, coal 28−36%, oil 15−23%, and wood/other having the greatest disparity of 23−35% of the total (gas- plus particle-phase) PAHs. Seasonal trends were found for both coal and oil. Coal was the dominate PAH source during the summer while oil dominated during the winter. Positive matrix factorization was the only method to segregate diesel from gasoline sources. These methods indicate the number and relative strength of PAH sources to the ambient urban atmosphere. As with all source apportionment techniques, these methods require the user to objectively interpret the resulting source profiles.
Sediment contamination is a major environmental issue in many urban watersheds and coastal areas due to the potential toxic effects of contaminants on biota and human health. Characterizing and ...delineating areas of sediment contamination and toxicity are important goals of coastal resource management in terms of ecological and economical perspectives. Core and surficial sediment samples were collected from an industrialized urban watershed at the East Coast of the United Stated and analyzed to evaluate the PCB contamination profile and toxicity resulting from dioxin-like PCBs as well as reductive dechlorination potential of indigenous PCB halorespiring bacteria through dechlorination activity assays. To support the experimental results an anaerobic dechlorination model was applied to identify microbial dechlorination pathways. The total PCB concentration in core samples ranged from 3.9 to 225.6 ng/g·dry weight (dw) decreasing with depth compared to 353.2 to 1213.7 ng/g·dw in surficial samples. The results of this study indicated an increase in PCB contamination over the last century as the industrial activity intensified. The toxicity resulting from dioxin-like PCBs was reduced up to 94% in core samples via 21 pathways resulting from the dechlorination model. Dechlorination rates in surficial sediment were between 1.8 and 13.2 · 10−3 mol% PCB116/day, while lower rates occurred in the core sediment samples. Dechlorination was achieved mainly through meta followed by para dechlorination. However, the rarer ortho dechlorination was also observed. Detection of indigenous PCB dechlorinating bacteria in the sediments and reduction of toxicity indicated potential for natural attenuation when point and nonpoint source PCBs in the urban watershed are controlled and PCB loading reduced.
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•Recontamination of superficial sediment with PCBs is occurring in Baltimore Harbor.•Sediment core PCB profile showed historic Aroclor 1260 contamination in Baltimore Harbor.•Toxicity associated with dioxin-like PCBs was reduced by 94% via microbial reductive dechlorination.•21 toxicity reducing pathways were identified with an anaerobic dechlorination model.
Bacterial and nutrient contamination from anthropogenic sources impacts fresh and marine waters, reducing water quality and restricting recreational and commercial activities. In many cases the ...source of this contamination is ambiguous, and a tracer or set of tracers linking contamination to source would be valuable. In this work, the effectiveness of utilizing a suite of Contaminants of Emerging Concern (CECs) as tracers of bacteria from human septic system effluent is investigated.
Field sampling was performed at more than 20 locations over approximately 18 months and analyzed for a suite of CECs and fecal coliform bacteria. The sampling locations included seeps and small freshwater discharges to the shoreline. Sites were selected and grouped according to level of impact by septic systems as determined by previous field sampling programs. A subset of selected locations had been positively identified as being impacted by effluent from failing septic systems through dye testing. The CECs were selected based on their predominant use, their frequency of use, and putative fate and transport properties.
In addition, two rounds of focused sampling were performed at selected sites to characterize short-term variations in CEC and fecal coliform concentrations, and to evaluate environmental persistence following source correction activities.
The results indicate that a suite of common use compounds are suitable as generalized tracers of bacterial contamination from septic systems and that fate and transport properties are important in tracer selection. Highly recalcitrant or highly labile compounds likely follow different loss profiles in the subsurface compared to fecal bacteria and are not suitable tracers. The use of more than one tracer compound is recommended due to source variability of septic systems and to account for variations in the subsurface condition. In addition, concentrations of some CECs were measured in receiving waters at levels which suggested the potential for environmental harm, indicating that the possible risk presented from these sources warrants further investigation.
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•Contaminants of Emerging Concern (CECs) enter surface waters from septic systems.•Common use moderately labile CECs can be effective tracers of bacteria from septics.•Due to variations in use and hydrology utilizing a suite of tracers is recommended.•CEC concentration to receiving water can vary 1–2 orders of magnitude over 24 h.•CECs from septic systems may occur at levels of ecotoxicological concern.
Untreated urban stormwater runoff contributes to poor water quality in receiving waters. The ability to identify toxicants and other bioactive molecules responsible for observed adverse effects in a ...complex mixture of contaminants is critical to effective protection of ecosystem and human health, yet this is a challenging analytical task. The objective of this study was to develop analytical methods using liquid chromatography coupled to high-resolution quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) to detect organic contaminants in highway runoff and in runoff-exposed fish (adult coho salmon, Oncorhynchus kisutch). Processing of paired water and tissue samples facilitated contaminant prioritization and aided investigation of chemical bioavailability and uptake processes. Simple, minimal processing effort solid phase extraction (SPE) and elution procedures were optimized for water samples, and selective pressurized liquid extraction (SPLE) procedures were optimized for fish tissues. Extraction methods were compared by detection of non-target features and target compounds (e.g., quantity and peak area), while minimizing matrix interferences. Suspect screening techniques utilized in-house and commercial databases to prioritize high-risk detections for subsequent MS/MS characterization and identification efforts. Presumptive annotations were also screened with an in-house linear regression (log K
vs. retention time) to exclude isobaric compounds. Examples of confirmed identifications (via reference standard comparison) in highway runoff include ethoprophos, prometon, DEET, caffeine, cotinine, 4(or 5)-methyl-1H-methylbenzotriazole, and acetanilide. Acetanilide was also detected in runoff-exposed fish gill and liver samples. Further characterization of highway runoff and fish tissues (14 and 19 compounds, respectively with tentative identification by MS/MS data) suggests that many novel or poorly characterized organic contaminants exist in urban stormwater runoff and exposed biota.
Background & Aims:
Studies comparing long-term success after pneumatic dilatation (PD) and laparoscopic Heller myotomy (HM) are lacking. This study compares long-term outcome of PD (single dilatation ...and graded approach) and laparoscopic HM and identifies risk factors for treatment failure.
Methods:
A cross-sectional follow-up evaluation of an achalasia cohort treated between 1994 and 2002 was followed-up for a mean of 3.1 years. There was a total of 106 patients treated by graded PD (1–3 dilatations with progressively larger balloons) and 73 patients treated by HM (20 had failed graded PD and crossed over to HM). A symptom assessment (structured telephone interview or clinic visit) was performed and patients were given freedom from alternative therapies to determine treatment outcome. Endoscopy, manometry, and timed barium esophagram were performed to determine the cause of treatment failure.
Results:
The success of single PD was defined as freedom from additional PDs: 62% at 6 months and 28% at 6 years (risk factors for failure: younger age, male sex, wider esophagus, and poor emptying on posttreatment timed barium esophagram). Freedom from subsequent PDs increased with each dilatation (graded PD). The success of graded PD and HM, defined as dysphagia/regurgitation less than 3 times/wk or freedom from alternative treatment, was similar: 90% vs 89% at 6 months and 44% vs 57% at 6 years (no risk factors for failure were identified). Causes of symptom recurrence were incompletely treated achalasia (96% after PD vs 64% after HM) and gastroesophageal reflux disease (4% after PD vs 36% after HM).
Conclusions:
No treatment cures achalasia. Short- and long-term success is similar for graded PD and laparoscopic HM. Therapeutic success decreases steadily over time. Achalasia patients need careful long-term follow-up evaluation.
Prediction of vertebrate health effects originating from persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) has remained a challenge for decades thus making the ...identification of bioindicators difficult. POPs are predominantly present in soil and sediment, where they adhere to particles due to their hydrophobic characteristics. Animals inhabiting soil and sediment can be exposed to PCBs via dermal exposure while others may obtain PCBs through contaminated trophic interaction. Freshwater turtles can serve as bioindicators due to their strong site fidelity, longevity and varied diet. Previous research observed the health effects of PCBs on turtles such as decreased bone mass, changed sexual development and decreased immune responses through studying both contaminated sites along with laboratory experimentation. Higher deformity rates in juveniles, increased mortality and slower growth have also been observed. Toxicological effects of PCBs vary between species of freshwater turtles and depend on the concertation and configuration of PCB congeners. Evaluation of ecotoxicological effects of PCBs in non-endangered turtles could provide important knowledge about the health effects of endangered turtle species thus inform the design of remediation strategies. In this review, the PCB presence in freshwater turtle habitats and the ecotoxicological effects were investigated with the aim of utilizing the health status to identify areas of focus for freshwater turtle conservation.
•PCBs cause increased deformity and mortality rates in juvenile freshwater turtles.•Toxicological effects are depending on the PCB concertation and configuration.•The common snapping turtle is more robust than diamondback terrapins and red-eared sliders.•Freshwater turtles can serve as bioindicators due to strong site fidelity and longevity.
The congener 2,2‘,3,3‘,4,4‘,5,5‘,6,6‘-decabromodiphenyl ether (BDE 209) is the primary component in a commonly used flame retardant known as decaBDE. This flame retardant constitutes approximately ...80% of the world market demand for polybrominated diphenyl ethers (PBDEs). Because this compound is very hydrophobic (log K ow ∼ 10), it has been suggested that BDE 209 has very low bioavailability, although debromination to more bioavailable metabolites has also been suggested to occur in fish tis- sues. In the present study, juvenile carp were exposed to BDE 209 amended food on a daily basis for 60 days, fol- lowed by a 40-day depuration period in which the fate of BDE 209 was monitored in whole fish and liver tissues sepa- rately. No net accumulation of BDE 209 was observed throughout the experiment despite an exposure concentration of 940 ng/day/fish. However, seven apparent debrominated products of BDE 209 accumulated in whole fish and liver tissues over the exposure period. These debrominated metabolites of BDE 209 were identified as penta- to octaBDEs using both GC/ECNI-MS and GC/HRMS. Using estimation methods for relative retention times of phenyl substitution patterns, we have identified possible structures for the hexa- and heptabromodiphenyl ethers identified in the carp tissues. Although exposure of carp to BDE 209 did not result in the accumulation of BDE 209 in carp tissues, our results indicate evidence of limited BDE 209 bioavailability from food in the form of lower brominated metabolites.
Gas and particle phase concentrations of 26 nitro-PAHs were quantified in ambient air collected in downtown Baltimore, MD, an urban region, and in Fort Meade, MD, a suburban area 20
km ...south-southeast of Baltimore, during January and July 2001. Total (gas+particle) concentrations for individual nitro-PAH compounds varied by as much as five times from sample to sample within each month. 2-Nitrofluoranthene and 9-nitroanthracene were the most abundant of the nitro-PAHs quantitatively analyzed in the air at both sites, accounting for approximately half of the total nitro-PAH concentrations during January and July. Concentrations at Baltimore were on average two to three times higher than those measured at the Fort Meade site. Concentrations for most nitro-PAHs were higher in January than in July, suggesting a reduction in photodecay of nitro-PAHs during January promoted the accumulation of nitro-PAHs. Concentrations of nitro-PAHs produced from gas-phase reactions were significantly correlated with concentrations of oxides of nitrogen (NO
x
) measured simultaneously at the Fort Meade site. 3-Nitrophenanthrene and 4-nitrophenanthrene were negatively correlated with NO
x
and were the only nitro-PAHs correlated with O
3, suggesting a different formation mechanism for these compounds compared to the other nitro-PAHs found in this study. The relative contribution of gas-phase reactions and primary emission sources of nitro-PAHs were evaluated using source specific concentration ratios of 2-nitrofluoranthene and 1-nitropyrene (2-NF/1-NP). The mean ratios of 2-NF/1-NP at both sites were statistically higher in July than January, indicating gas-phase reactions were an important source of 2-nitrofluoranthene in the summer. However, in January, gas-phase reactions were reduced, the NO
3-initiated reaction in particular, and primary emissions may significantly contribute to ambient nitro-PAH levels. The two dominant gas-phase production pathways of nitro-PAHs from the OH and NO
3-initiated reactions were investigated using concentration ratios of 2-nitrofluoranthene and 2-nitropyrene (2-NF/2-NP). At both sites, 2-NF/2-NP ratios indicated that the daytime OH-initiated reaction was the dominant gas-phase formation pathway. The estimated contributions of nitro-PAHs produced through gas-phase reactions via the OH pathway during July were >45% and during January were >83% at both Fort Meade and Baltimore.
Polybrominated diphenyl ether (PBDE) congener patterns in biota are often enriched in tetra-, penta-, and hexabrominated diphenyl ethers, which is believed to result from the use of the commercial ...“pentaBDE” formulation. However, our evidence suggests that debromination of PBDEs occurs within fish tissues leading to appreciable ac cumulation of less brominated congeners. This suggests that PBDE body burdens can reflect both direct uptake from exposure and debromination of more highly brominated congeners. We conducted two independent dietary exposure studies using the common carp (Cyprinus carpio) to trace the fate of 2,2‘,4,4‘,5-pentabromodiphenyl ether (BDE 99) and 2,2‘,3,4,4‘,5‘,6-heptabromodiphenyl ether (BDE 183) in fish tissues. Carp were fed food spiked with individual BDE congeners for 62 d, and depuration was monitored during the following 37 d. Significant debromination was observed, converting BDE 99 to 2,2‘,4,4‘-tetrabromodiphenyl ether (BDE 47) and BDE 183 to 2,2‘,4,4‘,5,6-hexabromodiphenyl ether (BDE 154) and another as yet unidentified hexa-BDE congener. The BDE 99 concentration rapidly declined from 400 ± 40 ng/g ww in the food to 53 ± 12 ng/g ww in the gut content material sampled 2.5 ± 1 h following feeding. At least 9.5 ± 0.8% of the BDE 99 mass in the gut was debrominated to BDE 47 and assimilated in carp tissues. In the BDE 183 exposure, approximately 17% of the BDE 183 mass was debrominated and accumulated in carp tissues in the form of two hexa-BDE congeners. In both exposure studies, the concentration of the exposure compound decreased significantly in the gut within 2.5 ± 1 h following ingestion. This rapid decrease in the concentration of the BDE congeners could not be explained entirely by debromination to quantified products or fecal egestion. Reactions occurring within the gut transform BDE congeners to other products that may accumulate or be excreted. Further studies are needed to identify and determine the effects of these BDE metabolites.
This study presents two methods for the quantification of nitro-substituted and parent polycyclic aromatic hydrocarbons (NPAH and PAH, respectively), respectively, utilizing large volume injection ...gas chromatography/mass spectrometry (GC/MS). Both methods (PAH and NPAH, respectively) employed a programmed temperature vaporization injector (PTV) in solvent vent mode, optimized using standard solutions. For the PAH method, the precision of the PTV was comparable to hot splitless injection for exhibiting a percent relative standard deviation (%RSD) consistently below 8% for 100
pg injections. Compound %RSDs for the NPAH method were consistently below 5% using the PTV. Microgram quantities (30–500
μg) of particulate matter Standard Reference Materials (SRM 1649 and 1650, National Institutes of Standards and Technology) were analyzed to simulate PAH and NPAH quantification on small aerosol mass loadings. The method detection limits from this study suggest PAHs and NPAHs can be easily quantified using low-volume samplers (>5
Lpm) on hourly timescales. In addition, this technique enabled the quantification of 12-h NPAH size distributions in the Baltimore, MD, atmosphere.
