Environmental Science & Technology Letters Environ.最新文献

Humans are exposed to toxic methylmercury mainly by consuming marine fish. While reducing mercury emissions and releases aims to protect human health, it is unclear how this affects methylmercury concentrations in seawater and marine biota. We compiled existing and newly acquired mercury concentrations in tropical tunas from the global ocean to explore multidecadal mercury variability between 1971 and 2022. We show the strong inter-annual variability of tuna mercury concentrations at the global scale, after correcting for bioaccumulation effects. We found increasing mercury concentrations in skipjack in the late 1990s in the northwestern Pacific, likely resulting from concomitant increasing Asian mercury emissions. Elsewhere, stable long-term trends of tuna mercury concentrations contrast with an overall decline in global anthropogenic mercury emissions and deposition since the 1970s. Modeling suggests that this limited response observed in tunas likely reflects the inertia of surface ocean mercury with respect to declining emissions, as it is supplied by legacy mercury that accumulated in the subsurface ocean over centuries. To achieve measurable declines in mercury concentrations in highly consumed pelagic fish in the near future, aggressive emission reductions and long-term and continuous mercury monitoring in marine biota are needed.

Source apportionment of per- and polyfluoroalkyl substances (PFAS) requires an understanding of the mass loading of these compounds in river basins. However, there is a lack of temporally variable and catchment-scale mass loading data, meaning identification and prioritization of sources of PFAS to rivers for management interventions can be difficult. Here, we analyze PFAS concentrations and loads in the River Mersey to provide the first temporally robust estimates of PFAS export for a European river system and the first estimates of the contribution of wastewater treatment works (WwTWs) to total river PFAS export. We estimate an annual PFAS export of 68.1 kg for the River Mersey and report that the yield of perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in the catchment is among the highest recorded globally. Analysis of river and WwTW loads indicates approximately one-third of PFOA emitted from WwTWs is potentially stored in the catchment and approximately half of PFOS transported by the River Mersey may not originate from WwTWs. As governments move toward regulation of PFAS in WwTW effluents, our findings highlight the complexity of PFAS source apportionment and the need for catchment-scale mass loading data. This study indicates that strategies for reducing PFAS loading that focus solely on WwTW effluents may not achieve river water quality targets.

Fluoropolymers are a class of per- and polyfluoroalkyl substances (PFAS) defined as high molecular weight plastics containing only carbon-based backbones with F atoms directly attached. Here, we used targeted and nontargeted analytical methods to quantify the aqueous leaching of small-molecule PFAS from three types of fluoropolymer tubing material and three types of nonfluorinated polymer tubing material. C₂–C₄ perfluoroalkyl carboxylic acids (PFCAs) were quantified with ion chromatography–mass spectrometry, and C₄–C₉ PFCAs were quantified with liquid chromatography–tandem mass spectrometry. A new ¹⁹F nuclear magnetic resonance (NMR) method with lower detection limits provided an unbiased, nontargeted view of all fluorinated chemicals in the aqueous leachate. C₂–C₄ PFCAs had a higher concentration than longer-chain PFCAs. All tubing tested, including the nonfluorinated polymers, contained trifluoroacetic acid (C₂ PFCA) concentrations above the blank. NMR identified additional fluorinated chemicals, especially in the nonfluorinated PEEK, a common replacement for fluoropolymers in laboratory chromatography systems. Overall, each fluoropolymer tested had different fingerprints of C₂–C₄ PFCAs, which may be related to their synthetic production such as processing aids, residuals, and inhibitors used; fluorinated chemicals were also identified from nonfluorinated polymers. The outcome of this work informs better trace analysis in the laboratory and presents an indication of how fluoropolymers and other plastics can be an emission source to the environment.

The petroleum refining industry is the key contributor to industrial volatile organic compounds (VOCs). To establish refined emission factors (EFs) and a source profile, 76 samples from eight refineries were collected using 33 processes. Arithmetic and weighted average methods were used to produce composites of the source profiles. EFs of eight emission sources (0.027–0.96 kg of VOCs/t of crude) were estimated and further classified with different control technology levels. EFs of all refineries ranged from 0.67 to 2.77 kg of VOCs/t of crude. Equipment leak (EL) was the largest emission source (37.65–76.70%), followed by storage tank (ST), loading operation (LO), and wastewater collection and treatment systems (WT). EFs of the EL, ST, WT, LO, cooling tower, processing vent (PV), stationary combustion, and flare were 0.96 ± 0.45, 0.28 ± 0.18, 0.17 ± 0.12, 0.093 ± 0.091, 0.070 ± 0.070, 0.028 ± 0.017, 0.010 ± 010, and 0.027 ± 0.023 kg of VOCs/t of crude, respectively. Alkanes made the largest contribution to the petroleum refining industry, followed by OVOCs and aromatics. Ethane, propane, isobutane, n-butane, isopentane, and n-pentane were the major species. Toluene, benzene, ethylene, and propene in EL, n-butyl acetate and acetone in ST, toluene and benzene in WT, MTBE in LO, and n-hexane in PV were dominant in the corresponding sources.

Chemical pollution can threaten biodiversity at different levels, from genetically diverse populations (genetic diversity) to different species (species diversity) and ecosystem traits/interactions (functional diversity). Most assessments of chemical impacts on different biodiversity levels depend on wet lab and field experiments, including sequencing large numbers of organisms, environmental DNA approaches, single chemical–species–outcome toxicity tests, and trait-based methods. However, it is impossible to assess all chemicals, species, populations, and ecosystems using these methods. Therefore, we advocate that computational methods are necessary to characterize, quantify, and predict chemical impacts on biodiversity. We briefly introduce the current state of research into chemical impacts on genetic diversity, species diversity, and functional diversity and describe new opportunities for computational methods like data integration, machine learning, cross-species/cross-ecosystem extrapolation, adverse outcome pathways, and Bayesian methods to support research in these three areas. By harnessing data and methods currently at our disposal and preparing methods to take advantage of continuously emerging data sets, computational approaches can be paired with environmental monitoring so different levels of biological organization can serve as consecutive warning signs for chemical impacts on biodiversity. This will enable effective ecosystem protection measures to be better developed and implemented to prevent biodiversity loss from chemical pollution.

The increasing popularity of seed treatment applications in agriculture may leave unintended hazards to soil biota, such as earthworms. The objective of this study was to explore mitochondrial DNA toxicity resulting from sublethal exposures to systemic pesticides, including four neonicotinoid insecticides (neonics), as well as coexposure to difenoconazole (DIF), a triazole fungicide, in earthworms (Eisenia fetida) in vivo. Earthworms were exposed under dose regimes resembling label recommendation and levels left in soil post seed treatment application for 30 days in an earthworm breeding facility. Mitochondrial DNA copy numbers (mtDNAcn) in earthworms were determined by using the 2^–ΔCt algorithm. Earthworms’ body weights were recorded before and after the exposure period. We found a highly significant increase of mtDNAcn in earthworms across all exposure groups (ANOVA, p < 0.001), either under a single neonic or combined with DIF exposure. Coupled with mtDNA toxicity, earthworms in the treatment groups gained significantly less weight than control earthworms (ANOVA, p < 0.001). We concluded that systemic pesticides, both neonics and DIF, posed mtDNA toxicity as measured by mtDNAcn, in earthworms.

Trace element is known to be one major component in determining particulate matter (PM) toxicities. However, there is still no accurate assessment of the toxic potency of the mixed valences. Here, we reported the oxidative stress and cytotoxicity potencies of 14 trace elements in their various valence states and estimated the toxic gaps of inorganic PM resulting from variations in element valences. Substantial discrepancies of up to 3 orders of magnitude in toxic potencies were observed among their different valences. When considering their abundance in PM, the toxicity gaps are estimated to range from 5 to 6 times between the greatest and weakest toxic valence states in the inorganic PM emitted from industrial sources, with iron contributing to 65.5%–91.0% of the overall gaps. Furthermore, the relative toxic variation of inorganic PM shows a significant correlation with the additive toxicities of Fe(II) and Fe(III) ions during aging process. The finding highlights that the multiple coexisting valence states of trace elements in PM need to be taken into account when estimating their toxic potencies.

Climate change has contributed to the increased frequency and intensity of wildfires. Studying its acute effects is limited due to the unpredictable nature of the occurrence of wildfires, which necessitates readily deployable techniques for collecting biospecimens. To identify biomarkers of the acute effects of wildfires, we conducted this exploratory study in eight healthy campers (four men and four women) who self-collected nasal fluid, urine, saliva, and skin wipes at different time points before, during, and after exposure to wood smoke for 4 h during a camping event. Concentrations of black carbon in the air and polycyclic aromatic hydrocarbons in participants’ silicone wristbands were significantly increased during the exposure session. Among 30 arachidonic acid metabolites measured, lipoxygenase metabolites were more abundant in nasal fluid and saliva whereas cyclooxygenase and non-enzymatic metabolites were more abundant in urine. We observed drastic increases, 8 h following the exposure, in urinary levels of PGE2 (398%) and 15-keto-PGF2α (191%) [false discovery rate (FDR) < 10%], with greater increases in men (FDR < 0.01%) than in women. No significant changes were observed for other metabolites in urine or the other biospecimens. Our results suggest urinary PGE2 and 15-keto-PGF2α as promising biomarkers reflecting pathophysiologic (likely sex-dependent) changes induced by short-term exposure to wildfires.

Resin-coated proppants (RCPs) are used in hydraulic fracturing of oil and gas wells to improve well performance; however, these proppants could be a cause for environmental concern if they are disposed of improperly. In this study, we investigate the water-leachable organic and inorganic constituents from proppants collected from surficial releases of RCPs in southeastern New Mexico. Significant concentrations of nonvolatile dissolved organic matter (>100 mg C/L) and phenolic compounds (>50 mg phenol/L) were identified in one of the proppant leachates, with further gas chromatography–mass spectrometry analysis identifying isomers of bisphenol F, a known endocrine disruptor analogous to bisphenol A, as the main organic constituents within this leachate. Fluorescence excitation–emission matrices analyses of proppant leachates identified several peaks associated with phenolic compounds, similar to previously studied oilfield wastewaters. Precursors of polyurethane production, including the inhalation sensitizer methylene diphenyl diisocyanate, were identified in the leachate from another proppant sample. An understanding of leachable compounds from RCPs is vital to management of environmental contamination from surficial releases, protecting the public and industry workers from associated hazards, and identifying the sources of organic compounds in oilfield wastewaters.