Refine search
Results 1901-1910 of 8,088
Thallium and lead variations in a contaminated peatland: A combined isotopic study from a mining/smelting area Full text
2021
Vaněk, Aleš | Vejvodová, Kateřina | Mihaljevič, Martin | Ettler, Vojtéch | Trubač, Jakub | Vaňková, Maria | Goliáš, Viktor | Teper, Leslaw | Sutkowska, Katarzyna | Vokurková, Petra | Penížek, Vít | Zádorová, Tereza | Drábek, Ondřej
Vertical profiles of Tl, Pb and Zn concentrations and Tl and Pb isotopic ratios in a contaminated peatland/fen (Wolbrom, Poland) were studied to address questions regarding (i) potential long-term immobility of Tl in a peat profile, and (ii) a possible link in Tl isotopic signatures between a Tl source and a peat sample. Both prerequisites are required for using peatlands as archives of atmospheric Tl deposition and Tl isotopic ratios as a source proxy. We demonstrate that Tl is an immobile element in peat with a conservative pattern synonymous to that of Pb, and in contrast to Zn. However, the peat Tl record was more affected by geogenic source(s), as inferred from the calculated element enrichments. The finding further implies that Tl was largely absent from the pre-industrial emissions (>~250 years BP). The measured variations in Tl isotopic ratios in respective peat samples suggest a consistency with anthropogenic Tl (ε²⁰⁵Tl between ~ -3 and −4), as well as with background Tl isotopic values in the study area (ε²⁰⁵Tl between ~0 and −1), in line with detected ²⁰⁶Pb/²⁰⁷Pb ratios (1.16–1.19). Therefore, we propose that peatlands can be used for monitoring trends in Tl deposition and that Tl isotopic ratios can serve to distinguish its origin(s). However, given that the studied fen has a particularly complicated geochemistry (attributed to significant environmental changes in its history), it seems that ombrotrophic peatlands could be better suited for this type of Tl research.
Show more [+] Less [-]Marine mammals and microplastics: A systematic review and call for standardisation Full text
2021
Zantis, Laura J. | Carroll, Emma L. | Nelms, Sarah E. | Bosker, Thijs
Microplastics receive significant societal and scientific attention due to increasing concerns about their impact on the environment and human health. Marine mammals are considered indicators for marine ecosystem health and many species are of conservation concern due to a multitude of anthropogenic stressors. Marine mammals may be vulnerable to microplastic exposure from the environment, via direct ingestion from sea water, and indirect uptake from their prey. Here we present the first systematic review of literature on microplastics and marine mammals, composing of 30 studies in total. The majority of studies examined the gastrointestinal tracts of beached, bycaught or hunted cetaceans and pinnipeds, and found that microplastics were present in all but one study, and the abundance varied between 0 and 88 particles per animal. Additionally, microplastics in pinniped scats (faeces) were detected in eight out of ten studies, with incidences ranging from 0% of animals to 100%. Our review highlights considerable methodological and reporting deficiencies and differences among papers, making comparisons and extrapolation across studies difficult. We suggest best practices to avoid these issues in future studies. In addition to empirical studies that quantified microplastics in animals and scat, ten studies out of 30 (all focussing on cetaceans) tried to estimate the risk of exposure using two main approaches; i) overlaying microplastic in the environment (water or prey) with cetacean habitat or ii) proposing biological or chemical biomarkers of exposure. We discuss advice and best practices on research into the exposure and impact of microplastics in marine mammals. This work on marine ecosystem health indicator species will provide valuable and comparable information in the future.
Show more [+] Less [-]Evaluation of wetland substrates for veterinary antibiotics pollution control in lab-scale systems Full text
2021
Liu, Lin | Li, Jie | Xin, Yu | Huang, Xu | Liu, Chaoxiang
The behaviors of typical veterinary antibiotics (oxytetracycline, ciprofloxacin and sulfamethazine) and 75 types of corresponding antibiotic resistant genes (ARGs) in four substrate systems (zeolite, gravel, red brick, and oyster shell) were investigated in this study. The results indicated that during treating synthetic livestock wastewater with individual antibiotic influent concentration of 100 μg/L, the effluent contained oxytetracycline and ciprofloxacin concentrations of 0.7–1.5 μg/L and 1.0–1.9 μg/L, respectively, in the zeolite and red brick systems, which were significantly lower than those of the other substrate systems (4.6–14.5 μg/L). Statistical correlation analyses indicated that the difference regarding oxytetracycline and ciprofloxacin removal among the four substrates was determined by their adsorption capacity which was controlled by the chemisorption mechanism. The average removal efficiency of sulfamethazine in the gravel system (48%) was higher than that of the other substrate systems (34–45%), and biodegradation may alter the sulfamethazine performance because of its co-metabolism process. Although tetG, floR, sul1, and qacEΔ1 were the dominant ARGs in all substrate systems (8.74 × 10⁻²-6.34 × 10⁻¹), there was difference in the total ARG enrichment levels among the four substrates. Oyster shell exhibited the lowest total relative abundance (1.56 × 10⁰) compared to that of the other substrates (1.82 × 10⁰–2.27 × 10⁰), and the ARG total relative abundance exhibited significant negative and positive correlations with the substrate pH and system bacterial diversity (P < 0.05), respectively. In summary, this study indicated that due to the difference of adsorption capacity and residual abundant nutrient in wastewater, the wetland substrate selection can affect the removal efficiency of veterinary antibiotics, and antibiotics may not be the determining factor of ARG enrichment in the substrate system.
Show more [+] Less [-]Di (2-ethylhexyl) phthalate impairs primordial follicle assembly by increasing PDE3A expression in oocytes Full text
2021
Liu, Jing-Cai | Yan, Zi-Hui | Li, Bo | Yan, Hong-Chen | De Felici, M. (Massimo) | Shen, Wei
It is known that Di (2-ethylhexyl) phthalate (DEHP) may impact mammalian reproduction and that in females one target of the drug’s action is follicle assembly. Here we revisited the phthalate’s action on the ovary and from bioinformatics analyses of the transcriptome performed on newborn mouse ovaries exposed in vitro to DEHP, up-regulation of PDE3A, as one of the most important alterations caused by DEHP on early folliculogenesis, was identified. We obtained some evidence suggesting that the decrease of cAMP level in oocytes and the parallel decrease of PKA expression, consequent on the PDE3A increase, were a major cause of the reduction of follicle assembly in the DEHP-exposed ovaries. In fact, Pde3a RNAi on cultured ovaries reducing cAMP and PKA decrease counteracted the primordial follicle assembly impairment caused by the compound. Moreover, RNAi normalized the level of Kit, Nobox, Figla mRNA and GDF9, BMP15, CX37, γH2AX proteins in oocytes, and KitL transcripts in granulosa cells as well as their proliferation rate altered by DEHP exposure. Taken together, these results identify PDE3A as a new critical target of the deleterious effects of DEHP on early oogenesis in mammals and highlight cAMP-dependent pathways as major regulators of oocyte and granulosa cell activities crucial for follicle assembly. Moreover, we suggest that the level of intracellular cAMP in the oocytes may be an important determinant for their capability to repair DNA lesions caused by DNA damaging compounds including DEHP.
Show more [+] Less [-]Uncertainty quantification and atmospheric source estimation with a discrepancy-based and a state-dependent adaptative MCMC Full text
2021
Albani, Roseane A.S. | Albani, Vinicius V.L. | Migon, Helio dos Santos | Silva Neto, Antônio J.
We address the source characterization of atmospheric releases using adaptive strategies in Bayesian inference in combination with the numerical solution of the dispersion problem by a stabilized finite element method and uncertainty quantification in the measurements. The adaptive techniques accelerate the convergence of Monte Carlo Markov Chain (MCMC) algorithms, leading to accurate reconstructions of the source parameters. Such accuracy is illustrated by the comparison with results from previous works. Moreover, the technique used to simulate the corresponding dispersion problem allowed us to introduce relevant meteorological information. The uncertainty quantification also improves the quality of reconstructions. Numerical examples using data from the Copenhagen experimental campaign illustrate the effectiveness of the proposed methodology. We found errors in reconstructions ranging from 0.11% to 8.67% of the size of the search region, which is similar to results found in previous works using deterministic techniques, with comparable computational time.
Show more [+] Less [-]Reduction in VOC emissions by intermittent aeration in bioreactor landfills with gas-water joint regulation Full text
2021
Chu, Yi-Xuan | Wang, Jing | Tian, Guangming | He, Ruo
Landfill mining and reclamation is a new strategy for addressing the lack of space available for new landfills and realizing the sustainable development of landfills. A gas-water joint bioreactor landfill is regulated by injecting water and/or recirculating leachate, and a blasting aeration system to optimize waste stabilization. In this study, four landfill reactors were constructed to investigate the effects of ventilation methods, including continuous (20 h d⁻¹) and intermittent aeration (4 h d⁻¹ in continuous or 2-h aeration per 12 h, twice a day), on the degradation of organic matter and volatile organic compound (VOC) emissions in comparison with traditional landfills. A total of 62 VOCs were detected in the landfill reactors. Among them, halogenated compounds had the highest abundance (39.8–65.4 %), followed by oxygenated compounds, alkanes and alkenes, and aromatic compounds. Both intermittent and continuous aeration could accelerate the degradation of landfilled waste and increase the volatilization rate of VOCs. Compared with intermittent aeration, the degradation of landfilled waste was more quickly in the landfill reactor with continuous aeration. However, intermittent aeration could create anaerobic-anoxic-aerobic conditions, which were conducive to the growth and metabolism of anaerobic and aerobic microorganisms in landfills and thereby reduced more than 63.4 % of total VOC emissions from the landfill reactor with continuous aeration. Moreover, intermittent aeration could reduce the ventilation rate and decrease the cost of aeration by 80 % relative to continuous aeration. Firmicutes, Bacteroidetes, Proteobacteria and Tenericutes predominated in the landfill reactors. The environmental variables including organic matter and VOCs concentrations had significant influences on microbial community structure in the landfilled waste. These findings indicated that intermittent aeration was an effective way to accelerate the stabilization of landfilled waste and reduce the cost and environmental risks in bioreactor landfills with gas-water joint regulation.
Show more [+] Less [-]Effects of dim artificial light at night on locomotor activity, cardiovascular physiology, and circadian clock genes in a diurnal songbird Full text
2021
Alaasam, Valentina J. | Liu, Xu | Niu, Ye | Habibian, Justine S. | Pieraut, Simon | Ferguson, Brad S. | Zhang, Yong | Ouyang, Jenny Q.
Artificial light is transforming the nighttime environment and quickly becoming one of the most pervasive pollutants on earth. Across taxa, light entrains endogenous circadian clocks that function to synchronize behavioral and physiological rhythms with natural photoperiod. Artificial light at night (ALAN) disrupts these photoperiodic cues and has consequences for humans and wildlife including sleep disruption, physiological stress and increased risk of cardiovascular disease. However, the mechanisms underlying organismal responses to dim ALAN, resembling light pollution, remain elusive. Light pollution exists in the environment at lower levels (<5 lux) than tested in many laboratory studies that link ALAN to circadian rhythm disruption. Few studies have linked dim ALAN to both the upstream regulators of circadian rhythms and downstream behavioral and physiological consequences. We exposed zebra finches (Taeniopygia gutatta) to dim ALAN (1.5 lux) and measured circadian expression of five pacemaker genes in central and peripheral tissues, plasma melatonin, locomotor activity, and biomarkers of cardiovascular health. ALAN caused an increase in nighttime activity and, for males, cardiac hypertrophy. Moreover, downstream effects were detectable after just short duration exposure (10 days) and at dim levels that mimic the intensity of environmental light pollution. However, ALAN did not affect circulating melatonin nor oscillations of circadian gene expression in the central clock (brain) or liver. These findings suggest that dim ALAN can alter behavior and physiology without strong shifts in the rhythmic expression of molecular circadian pacemakers. Approaches that focus on ecologically-relevant ALAN and link complex biological pathways are necessary to understand the mechanisms underlying vertebrate responses to light pollution.
Show more [+] Less [-]Impact of fate properties, groundwater fluctuations and the presence of worm burrows on pesticide leaching assessments through golf areas Full text
2021
Karan, Sachin | Badawi, Nora | Jensen, Anne Mette D. | Rosenbom, Annette E.
The risk of pesticide leaching from recreational areas such as golf course turfs is not distinguished in a regulative framework within the EU where the focus is on agricultural soils. But with increasing popularity of golf, and thus, increasing number of golf courses leading to potentially increasing use of pesticides, understanding the processes determining pesticide leaching are critical to ensure optimal quality of both groundwater and golf turf. This study input the measured variation in fate properties of tebuconazole (TBZ) and MCPA as pure active ingredients and commercial products in simulations with realistic hydrological conceptualizations to investigate their implication in leaching assessments. Scenarios with (i) fluctuating and fixed groundwater levels and (ii) preferential flows including fluctuating and fixed groundwater levels were evaluated. The results showed that mobile MCPA leached in higher concentrations by a factor of 1.3 with fluctuating groundwater levels than with fixed groundwater levels. When preferential flow paths were incorporated in the models, the leaching was substantial for MCPA regardless of its formulation as active ingredient or commercial product, while in multiple simulations without preferential pathways there was no leaching of MCPA. Compared to MCPA leaching without preferential flow paths, the leaching concentrations increased up to a factor of 13.9 when preferential flows were included. With preferential flow paths, the increase in leaching concentration from fixed groundwater levels to fluctuating groundwater levels was up to a factor of 2.3 depending on the formulation of MCPA. This study demonstrated that it is imperative to assess fate parameters in the topsoil of golf courses and consider realistic groundwater BC (boundary condition) and the presence of preferential flow paths to obtain representative pesticide leaching risk assessments.
Show more [+] Less [-]Particulate characteristics of low-temperature combustion (PCCI and RCCI) strategies in single cylinder research engine for developing sustainable and cleaner transportation solution Full text
2021
Agarwal, Avinash Kumar | Singh, Akhilendra Pratap | Kumar, Vikram
In this experimental study, particulate matter (PM) characterizations of different low-temperature combustion (LTC) strategies have been compared with conventional compression ignition (CI) combustion for finding out a sustainable and cleaner transport solution. LTC strategies included premixed charge compression ignition (PCCI) and reactivity-controlled compression ignition (RCCI) combustion. Particulate sampling and characterization were carried out in a single-cylinder diesel engine. All engine tests were performed at 1, 2, 3, 4 bar brake mean effective pressure (BMEP) at 1500 rpm. CI and PCCI combustion experiments were performed using mineral diesel as the test fuel. However, mineral diesel and methanol were used as high reactivity fuel (HRF) and low reactivity fuel (LRF), respectively in the RCCI combustion strategy. For all combustion strategies, fuel injection pressure (FIP) was kept constant at 500 bar. However, the number of injections and start of injection (SoI) timings were varied to optimize the engine performance. Results showed that the RCCI combustion strategy emitted a relatively lower concentration of particles than the other two strategies (PCCI and CI). A relatively higher number concentration of accumulation mode particles (AMP) compared to nucleation mode particles (NMP) in the exhaust of the RCCI combustion strategy was an important finding of this study. Number-size and mass-size distributions of particles emitted from different strategies also exhibited the dominant concentration of particles in the CI combustion strategy. PM bound trace metal analysis was yet another critical aspect of this study, which showed that both RCCI and PCCI strategies emitted a relatively lower concentration of trace metals than the conventional CI combustion strategy. Parametric analysis of different PM characteristics and NOx-PM trade-off analysis also demonstrated the importance of LTC strategies over the conventional CI combustion strategy. Overall, this study demonstrated that all LTC strategies could be used for PM and NOx reduction; however, the RCCI combustion strategy was more dominant in NOx and PM reduction, in addition to having an excellent capability of using alternative fuel in the quest for developing sustainable transport solution.
Show more [+] Less [-]Simultaneous enantioselective analysis of illicit drugs in wastewater and surface water by chiral LC–MS/MS: A pilot study on a wastewater treatment plant and its receiving river Full text
2021
Wang, Weimin | Guo, Changsheng | Chen, Like | Qiu, Ziwen | Yin, Xingxing | Xu, Jian
An enantioselective method for quantifying amphetamine-type chiral illicit drugs (CIDs) in wastewater and surface water was developed, validated, and applied to samples from a wastewater treatment plant (WWTP) and its effluent-receiving river in Beijing, China. Water samples were subjected to solid-phase extraction (SPE) and then quantified via liquid chromatography–tandem mass spectrometry. The enantioseparation of CIDs was performed with a CHIRALPAK CBH column. Chromatographic parameters, including mobile phase composition and flow rates, were tested to identify the satisfactory enantiomeric resolution. The SPE method was optimized by evaluating variables, including SPE cartridge types, extraction solvents, and solvent volumes. The Oasis HLB sorbent showed good performance with recoveries exceeding 60% and matrix effects ranging from −19.6% to 26.6% for most target enantiomers, except for norephedrine (NE), in three different aquatic matrixes. The established method was superior to previously reported methods and had a low limit of detection, low limit of quantification, and short runtime (<45 min). The repeatability and reproducibility of the method reached 19.1% and 17.8%, respectively. The method was successfully utilized to monitor the daily variations in CIDs in the influent, effluent, and effluent-receiving river of a WWTP in Beijing over 1 week. The common occurrence of 1 R,2 S-(−)-ephedrine (1 R,2 S-(−)-EPH), 1 S,2 S-(+)-pseudoephedrine (1 S,2 S-(+)-PEPH), R-(−)-methamphetamine (METH), and S-(+)-METH in wastewater samples was observed. Ephedrines (1 R,2 S-(−)-EPH and 1 S,2 S-(+)-PEPH) were the most abundant CIDs in the influent, effluent, upstream, and downstream samples with concentrations of 725.8 ± 181.2 ng/L, 22.9 ± 4.9 ng/L, 12.96 ± 0.79 ng/L, and 11.6 ± 6.7 ng/L, respectively. METH was detectable in most water samples and was present in excess in S-enantiomer form in the influent and in R-enantiomer form in the effluent and surface water. R-(−)-MDMA was detected at a concentration of up to 2.4 ng/L in the influent. The metabolites norketamine (NK), amphetamine(AMP), MDA, and NE were not detected in water samples given the low concentration of their parent drugs.
Show more [+] Less [-]