Journal of hazardous materials letters最新文献

Rhodamine B is a synthetic dye released in huge quantities as hazardous colored effluents into aquatic ecosystems. It negatively affects the metabolic and physiological processes in aquatic plants. The goal of current study was to assess the impact of various Rhodamine B concentrations (5, 10, 15, 20, and 25 mg/L) on antioxidant and photosynthetic performance of Hydrilla verticillata exposed for 24, 48, and 72 h. Results of present study clearly demonstrate that Rhodamine B inhibits the activity of the superoxide dismutase (SOD), catalase (CAT), and guaiacol peroxidase (GPOD) in H. verticillata. Activities of SOD, CAT, and GPOD were constantly raised at lower concentrations and then decreased with increasing concentration and exposure duration of Rhodamine B. In vivo chlorophyll fluorescence experiments were used to examine its inhibitory effects on H. verticillata photosystem II (PSII). The OJIP fluorescence induction kinetics were altered by increasing the Rhodamine B concentration and treatment time as a result increasing the parameters Fo/Fm and φDo while decreasing Fm, φPo, Ψo, φEo, RC/CSm, ABS/CSm, TR/CSm, ET/CSm and, PI_abs. When exposed to Rhodamine B, electron transport is slowed down on both the acceptor and donor sides and overall decreases the photosynthetic performance of H. verticillata.

Ingested Microplastic (MP) particles can harm the human body. Estimations of the total mass of ingested MP particles correspond to 50 plastic bags per year (Bai et al., 2022), one credit card per week (Gruber et al., 2022), or a median value of 4.1 μg/week for adults (Mohamed Nor et al., 2021). The first two estimations are based on an analysis (Senathirajah et al., 2021) that predicts a total ingested mass of MP particles m_i,MP of 0.1–5 g/week. This work revisits and evaluates this calculation and compares its results and methods to Mohamed Nor et al. (2021). Senathirajah combines data of averaged MP particle masses ${\overline{m}}_{\mathrm{MP}}$ from papers that reported MP particle sizes and MP particle counts n_MP in shellfish, salt, beer, and water based on other papers that detected MP particles. Combined with the estimated weekly consumption of those consumables, they compute m_i,MP. This work raises some serious issues of Senathirajah in the way they combine data and they obtained particle sizes. It concludes that Senathirajah overestimates m_i,MP by several orders of magnitude and that m_i,MP can be considered as a rather irrelevant factor for the toxic effects of MP particles on the human body.

Heavy metals (HM) toxicity is becoming a major threat to living organisms in recent years due to the increase in population and anthropogenic activities. Lead (Pb) shares about 10% of total pollution produced by heavy metals. The uptake of lead by the primary producers (plants) is found to affect their metabolic functions, growth, and photosynthetic activity. The accumulation of lead in excess can cause up to a 42% reduction in the growth of the roots. The current review addresses the global status of lead contamination in soil, potential lead sources, and the mechanism of lead uptake by the plants. This article also provides information about the lead concentration in plants in polluted and non-polluted areas. Humans are directly or indirectly dependent on plants to meet their daily requirements. So, it becomes necessary to review the problems associated with lead pollution in plants and its mode of action affecting the plant system. Factors like bioaccumulation, bioavailability, bioconcentration, transfer factor, and the role of Casparian strips as a natural physical barrier are discussed. Further, the updated literature survey about the various bioremediation strategies utilized for its elimination is also presented. The current study suggests that more attention needs to be focused on evaluating the effectiveness of bioremediation methods.

Tellurium (Te) is a Critical Element that is toxic to microorganisms and humans alike, most notably in its soluble oxyanionic forms. To date, the biogeochemical behaviour of Te in Earth’s surface environment is largely unknown. Here, we report the discovery of elemental Te nanoparticles (Te NPs) in regolith samples using Single-Particle Inductively Coupled Plasma Mass Spectroscopy. Tellurium NPs were detected in both proximal and distal locations (bulk concentrations >4 ppm) relative to weathering Te ores. Synchrotron X-ray Fluorescence Mapping and X-ray Absorption Spectroscopy showed that bulk Te in the regolith is generally associated with Fe (oxyhydr)oxides and clay minerals, and mostly found in the oxidation states +IV and +VI. Although Te NPs account for less than 2 mol‰ of Te in our samples, their detection provides evidence for the active biogeochemical cycling of Te in surface environments. Te NPs are reactive and are likely to have formed in situ in distal samples, most likely via microbially-mediated reduction. Hence, the presence of Te NPs indicates the potential for release of toxic soluble forms of Te even in environments where most Te is “fixed” in forms such as Fe (oxyhydr)oxides that have low solubility and poor bioavailability.

Developing methods to quickly detect microplastics is critical to assessing the extent of microplastic contamination in the environment. However, current methods to quantify microplastics from environmental samples can take several hours to days and often require access to expensive specialized microscopy instruments. Herein we report a smartphone-based method to rapidly quantify microplastics. The method involves isolating microplastics from soil or water by density separation and vacuum filtration, staining the isolated plastic polymers with Nile Red, and quantifying the strained microplastics as small as 10 µm using a smartphone-based fluorescence microscope with an opti-mechanical attachment. The smartphone-enabled quantification using an algorithm eliminates time-consuming digestion steps and manual counting, thereby enabling quantification of microplastic concentration in environmental samples within 1 h. The method successfully detected a wide range of plastic polymers, but a dilution step was often needed if the samples contained high concentrations of particulates or non-plastic debris to minimize optical overlap or blocking. This method could serve as an initial assessment tool to rapidly quantify microplastics in environments in remote places with limited access to expensive resources and open the possibility to increase the frequency of monitoring microplastic concentration in engineered systems such as wastewater treatment plants.

Studies have identified hundreds of per- and polyfluoroalkyl substances (PFAS) in aqueous film forming foam (AFFF) using high resolution mass spectrometry (HRMS), and there is increasing reliance on HRMS with suspect screening in areas such as PFAS fate and transport. Characterization of active-use AFFF formulations is crucial for maintaining representative lists of PFAS for such efforts. Herein, targeted analysis, total oxidizable precursor assay (TOP), suspect screening, and non-targeted analysis were used to characterize PFAS in an AFFF currently certified for use by the U.S. military. The sum of PFAS identified during targeted analysis and suspect screening was compared to TOP, demonstrating that > 90% (20.2 mM) of the estimated total PFAS concentration (22.4 mM) was comprised of "unknown" PFAS. Tandem and multi-stage tandem mass spectra were used to annotate 10 PFAS within 9 classes, 8 of which have never been reported. A subset are fluorotelomer-based isomers of legacy, electrochemically synthesized PFAS. Thus, suspect screening efforts that rely solely on accurate mass matching may mis-annotate PFAS presented here as isomers that will have key differences in properties such as biotransformation pathways. The total estimated concentration of the 10 PFAS was ~20 mM, which agrees with the "unknown" fraction (20.2 mM) identified by TOP.

While it is thought that some per- and polyfluoroalkyl substances (PFAS) may volatilize from aqueous solutions, experimentally measured Henry’s Law constants (k_H, synonymous with air : water partition coefficient) are scarce. This leads to a lack of understanding of the partitioning of PFAS and an inability to predict concentrations above contaminated groundwater (e.g., vapor intrusion). We measured k_H for 27 PFAS via headspace analysis and manipulations of the gas to liquid phase ratio. Fifteen PFAS produced mass spectrometry signals suitable for k_H measurements. At 25 °C the experimentally measured dimensionless k_H were: 0.31 – 2.82 for four fluorotelomer alcohols (FTOHs), 0.09 – 0.18 for three fluorotelomer sulfonates (FTSs), 0.30 – 1.01 for three iodinated PFAS, 0.43 – 0.92 for two sulfonamides, 3.86 for 6:2 fluorotelomer olefin, 0.69 for 8:2 fluorotelomer carboxylic acid, and 0.32 for 8:2 fluorotelomer acrylate. Longer fluoroalkyl chain length resulted in increased k_H for FTOHs and FTSs, the only two groups in which chain length was studied. Perfluorinated sulfonates and carboxylates were generally not volatile enough to be measured, even at pH as low as 1, although fluorotelomers of both functional groups were measurably volatile. Temperature effects were well described by the van’t Hoff equation. k_H was not significantly different in various environmentally relevant matrices demonstrating the broad applicability of the produced constants.

Stormwater biofilters naturally experience dry-wet and freeze-thaw cycles, which could remobilize deposited particulate pollutants including microplastics. Yet, the effect of these natural weathering conditions on the mobility of deposited microplastics has not been evaluated. We deposited microplastics on columns packed with sand or a mixture of sand with soil (25% by volume) to simulate biofilter media, subjected them to intermittent infiltration events punctuated by either freeze-thaw cycles or drying cycles. Comparing the vertical distribution of microplastics in biofilters after both treatments, we showed that more than 90% of microplastics were retained within the first 3 cm of filter media, but the distribution in deeper layers varied with media type and treatment conditions. Freeze-thaw cycles were more effective than dry-wet cycles in increasing the downward mobility of deposited microplastics. We attributed these results to the disruption of filter media by expanding ice crystals, which could release deposited colloids and associated microplastics. An increase in natural colloid concentration in the effluent following freeze-thaw treatments confirmed the hypothesis. The results are useful in predicting microplastic transport in the root zone in stormwater biofilters or contaminated land experiencing natural freeze-thaw cycles.

Targeted analysis for 24 Per- and Polyfluoroalkyl Substances (PFAS) was conducted on 10 insecticide formulations used on a United States Department of Agriculture crop research field. Perfluorooctane sulfonic acid (PFOS) was found in 6 of the 10 formulations with concentrations ranging from 3.92 to 19.2 mg/kg. Further analysis of soil and plant samples collected at the site found several additional PFAS, with PFOS being the most prominent. Suspect screening was then conducted on the formulations and provided several suspected PFAS in addition to the 24 targeted analyzed PFAS in 7 of the 10 samples, one of which showed no PFAS during targeted analysis. PFAS-precursor oxidation was then conducted on the two insecticide formulations with the greatest lists of suspected PFAS as validation of potential unknown PFAS in the formulations. This study revealed a previously unknown potential PFAS contamination source for rural and agricultural environments.