Abstract In petroleum hydrocarbon (PHC)-contaminated subsoils, iron bioavailability often is believed to constrain the degradation of PHC contaminants, but spatially resolved evidence linking microbial activity with Fe transformations is scarce. Here, we bridge this gap by integrating phosphor imaging using positron-emitting radiotracer [18F]fluorobenzene─a high-fidelity surrogate for benzene, toluene, ethylbenzene, and xylene (BTEX)─with synchrotron-based X-ray spectroscopy. This multimodal approach allows for targeted mineralogical fingerprinting, guided by direct visualization of microbial activity within PHC-contaminated soils. Bulk X-ray absorption near-edge structure (XANES) showed little contrast, but microspectroscopy analysis revealed diffuse Fe at active zones and discrete Fe grains in inactive matrices, a pattern consistent with Fe(III) bioreduction to mobile Fe(II) and porewater transport before reprecipitation/reoxidation. Zones of high microbial activity were enriched in reactive phases (ferrihydrite, siderite, and green rust) comprising 27–71% of total Fe, whereas inactive matrices sequestered Fe mainly in Ca–Fe silicates with less than 25% reactive Fe. The recurring presence of green rust and vivianite aligns with phosphate-associated early-stage products under long-term tripolyphosphate biostimulation. We conclude that hydrocarbon degradation co-occurs spatially with Fe(III) bioreduction to mobile Fe(II), lateral transport in porewater, and phosphate-associated reoxidation/reprecipitation, processes that bulk methods often obscure but microscale mapping reveals. These insights support potential comanaging Fe and P amendments and targeted delivery of amendments to enhance PHC bioremediation in cold, calcareous soils.
Abstract The efficient conversion of CO2 and industrial waste streams into value-added products remains a critical challenge for sustainable microbial processes. Here, we present the first systematic demonstration of purple phototrophic bacteria (PPB) as platforms for the autotrophic valorization of CO2 and industrial off-gases or sulfur byproducts into valuable metabolites. Genome-guided screening combined with experimental validation identified strains capable of coupling photoautotrophic growth with the production of CoQ10 and carotenoid pigments. Among them, Rhodospirillum rubrum DSM 467 and DSM 107 exhibited the highest performance, maintaining stable CO2 and H2 consumption under semicontinuous operation and accumulating up to 9.6 ± 0.2 mgCoQ10 gbiomass–1 under CO2/ H2 conditions, comparable to engineered production systems. In addition, R. rubrum DSM 467 efficiently oxidized CO from syngas via the water–gas shift reaction, displaying hierarchical substrate utilization driven by energetic constraints. In contrast, Marichromatium purpuratum simultaneously oxidized H2 and thiosulfate (S2O32–), enabling parallel electron input into the photosynthetic electron transport chain and enhanced growth. Overall, these results establish PPB as robust and metabolically flexible biocatalysts for converting CO2 and industrial waste streams into high-value chemicals with direct applications in the pharmaceutical and nutraceutical industries.
Abstract Atmospheric microplastics (MPs) play an important role in the transport of MPs across diverse environmental media, yet their annual deposition dynamics across heterogeneous urban–cropland regions remain poorly understood. We conducted a one-year field campaign at three contrasting sites in the North China Plain (NCP): Beijing (BJ, urban), Tianjin (TJ, industrial/coastal), and Handan (HD, agricultural). Atmospheric bulk-deposition samples were characterized for particle deposition rates, size, morphology, and polymer composition, with observations evaluated using meteorological and land-cover information. Deposition rates were significantly higher in BJ than in TJ (p < 0.05) and HD (p < 0.001). Median (interquartile range) deposition rates were 34640 (18703–90472), 14367 (6000–25810), and 6990 (3903–11790) items m–2 d–1 in BJ, TJ, and HD, respectively. Small particles (20–50 μm) dominated particle abundance (80.7%), whereas fragments dominated particle morphology (90.4%). Backward trajectories indicated seasonal differences in potential air-mass transport pathways. Integrating particle mass estimates with land-cover data yielded order-of-magnitude estimates of annual atmospheric MP inputs of approximately 6 Gg to urban areas and 17 Gg to cropland in the northern NCP. These results reveal pronounced spatiotemporal variability in atmospheric MP deposition and highlight the dominance of small MP fragments across urban and cropland ecosystems.
Abstract Scientists and engineers have historically approached questions of environmental justice (EJ) differently from social scientists and humanists, from how they formulate problem scope to how they propose solutions. While scientists and engineers have assessed distributional injustices extensively, there are opportunities for deeper interdisciplinary collaboration with other EJ schools of thought. In this Perspective, we first present an EJ schematic for a science and engineering audience, where we trace epistemologies within EJ schools to show how EJ scholars conceptualize knowledge, how this relates to their methods, and how they present and publish work. We survey the EJ literature─mainly work related to the United States─across disciplines to determine major tensions within EJ and between EJ, science, and engineering scholarship. We also discuss possibilities for enabling interdisciplinary collaboration for scientists and engineers working on EJ-related questions by analyzing epistemological compatibilities. Next, we highlight opportunities to facilitate collaboration through an illustrative interdisciplinary case study. We conclude with takeaways for scientists and engineers moving forward, alongside some of the challenges accompanying interdisciplinary EJ research.
Abstract Biological wastewater treatment in cold regions faces a low-efficiency and high-energy paradox due to low-temperature inhibition. Inspired by plant phototropism, this study reports bioinspired phototropic endogenous heating (Bio-PEH) based on the underwater opto-thermomechanical response. Upon illumination, cryopolymerized macroporous reduced graphene oxide@poly(N-isopropylacrylamide) fibers undergo asymmetric contraction, which reorients the illuminated surface to be normal to the light vector, so as to maximize photothermal flux under oblique incidence. Meanwhile, flash heating further enhances water-confined heat transfer and expands the effective heating domain. Bio-PEH arrays raise bulk wastewater from 7.8 to 30.2 °C, which improves NH4+ removal by 2.8-fold, accounting for 25.3–169.7% enhancement compared with Joule heating (JH), direct solar heating (DH), and static endogenous heating (SEH). Global simulations further indicate multifold thermal compensation at high latitudes with substantial carbon and energy cost reduction. This study provides a biophysically inspired strategy by utilizing opto-thermomechanical response to realize heating of low-temperature wastewater, making wastewater treatment in cold regions more efficient, economical, and sustainable.
