Temporal Changes In Concentrations Research Articles

Temporal trends in exposure to parabens, benzophenones, triclosan, and triclocarban in adult females in Kyoto, Japan, from 1993 to 2016.

Products used in daily life can contain chemicals such as parabens, benzophenones, triclosan, and triclocarban that have potential endocrine-disrupting effects. Little is known about the temporal trends of exposure levels to some of these chemicals in Japan. Our study assessed the intake and risk associated with exposure to commonly used chemicals. We measured the concentrations of five parabens, four benzophenones, and triclosan and triclocarban in 133 single spot urine samples. The urine samples were collected in 1993, 2000, 2003, 2009, 2011, and 2016 from healthy female residents in Kyoto, Japan. With the exception of methylparaben, ethylparaben, and butylparaben, there were no significant fluctuations in the concentrations of target chemicals over the study period; however, methylparaben, ethylparaben, and butylparaben showed temporal changes in concentrations. Methylparaben concentrations peaked in 2003 with a median value of 309μg/g creatinine, ethylparaben concentrations peaked in 1993 with a median value of 17.3μg/g creatinine, and butylparaben showed a decline, with the median values becoming non-detectable in 2009 and 2016. We calculated estimated daily intakes and hazard quotients for each chemical. In the analysis of total samples, 2.3% (3 samples) for butylparaben and 0.8% (1 sample) for propylparaben were found to surpass a hazard quotient of 1. Overall, 3% (n = 4) of the study participants exceeded a hazard index of 1. The potential health risks associated with exposure to butylparaben and propylparaben emphasize the need for further monitoring and research.

Fate of synthetic chemicals in the agronomic insect pest Spodoptera littoralis: experimental feeding-contact assay and toxicokinetic model.

Insecticides prevent or reduce insect crop damage, maintaining crop quality and quantity. Physiological traits, such as an insect's feeding behavior, influence the way insecticides are absorbed and processed in the body (toxicokinetics), which can be exploited to improve species selectivity. To fully understand the uptake of insecticides, it is essential to study their total uptake and toxicokinetics independent of their toxic effects on insects. We studied the toxicokinetics (TK) of insecticidally inactive test compounds incorporating agro-like structural motifs in larvae of the Egyptian cotton leafworm (Spodoptera littoralis,Lepidoptera),and their distribution across all biological matrices, using laboratory experiments and modeling. We measured Spodoptera larval behavior and temporal changes of whole-body concentrations of test compounds during feeding on treated soybean leaf disks and throughout a subsequent depuration period. Differences in the distribution of the total quantities of compounds were found between the biological matrices leaf, larva, and feces. Rate constants for uptake and elimination of test compounds were derived by calibrating a toxicokinetic model to the whole-body concentrations. Uptake and elimination rate constants depended on the physicochemical properties of the test compounds. Increasing hydrophobicity increased the bioaccumulation potential of test compounds. Incomplete quantities in larval matrices indicated that some compounds may undergo biotransformation. As fecal excretion was a major elimination pathway, the variable time of release and number of feces pellets led to a high variability in the body burden. We provide quantitative models to predict the toxicokinetics and bioaccumulation potential of inactive insecticide analogs (parent compounds) in Spodoptera.

Household carbon monoxide (CO) concentrations in a large African city: An unquantified public health burden?

Carbon monoxide (CO) is a poisonous gas produced by incomplete combustion of carbon-based fuels that is linked to mortality and morbidity. Household air pollution from burning fuels on poorly ventilated stoves can lead to high concentrations of CO in homes. There are few datasets available on household concentrations of CO in urban areas of sub-Saharan African countries. CO was measured every minute over 24 h in a sample of homes in Nairobi, Kenya. Data on household characteristics were gathered by questionnaire. Metrics of exposure were summarised and analysis of temporal changes in concentration was performed. Continuous 24-h data were available from 138 homes. The mean (SD), median (IQR) and maximum 24-h CO concentration was 4.9 (6.4), 2.8 (1.0–6.3) and 44 ppm, respectively. 50% of homes had detectable CO concentrations for 847 min (14h07m) or longer during the 24-h period, and 9% of homes would have activated a CO-alarm operating to European specifications. An association between a metric of total CO exposure and self-reported exposure to vapours >15 h per week was identified, however this were not statistically significant after adjustment for the multiple comparisons performed. Mean concentrations were broadly similar in homes from a more affluent area and an informal settlement. A model of typical exposure suggests that cooking is likely to be responsible for approximately 60% of the CO exposure of Nairobi schoolchildren. Household CO concentrations are substantial in Nairobi, Kenya, despite most homes using gas or liquid fuels. Concentrations tend to be highest during the evening, probably associated with periods of cooking. Household air pollution from cooking is the main source of CO exposure of Nairobi schoolchildren. The public health impacts of long-term CO exposure in cities in sub-Saharan Africa may be considerable and should be studied further.

Dopamine Concentration Changes Associated with the Retrodialysis of Methylone and 3,4-Methylenedioxypyrovalerone (MDPV) into the Caudate Putamen.

Structural modifications to synthetic psychoactive cathinones (SPCs), a class of drugs that contain a β-keto modification of the phenethylamine pharmacophore of amphetamine, induce differences in dopamine transporter (DAT) activity. Here, in vivo retrodialysis was utilized to deliver the SPCs 3,4-methylenedioxypyrovalerone (MDPV, a DAT inhibitor) or methylone (a DAT substrate) into the caudate putamen of male Sprague-Dawley rats. Dialysate samples were collected prior to and post drug administration, and temporal changes in dopamine concentration were quantified using HPLC-EC methods. Methylone elicited a 200% increase and MDPV a 470% increase in dopamine levels at the 10 min time point. The findings demonstrate that in vivo retrodialysis can be used to evaluate the effects of SPCs on neurotransmission in the brain.

Investigation of river water pollution using Muskingum method and particle swarm optimization (PSO) algorithm

River water pollution is one of the most important environmental issues. Advection–dispersion equations are used to study the temporal changes in pollutant concentration along the study river reach. The use of advection–dispersion equations in investigating how the concentration of pollution is transformed requires a lot of data including river cross-section characteristics, dispersion coefficient, and upstream and downstream boundary conditions, etc. therefore, the corresponding calculations are very costly, difficult and time-consuming. In the present study, instead of using the mentioned equations, the linear Muskingum method (used in previous studies for flood routing) and the particle swarm optimization (PSO) algorithm was used for the first time to calculate the temporal changes in pollution concentration at different stream locations. The presented solution in the presented study is very accurate and only requires the temporal changes in concentration in the upstream and downstream of the study river reach and for this reason, it is very low-cost and easy to use and requires less time to collect data and perform calculations. In the proposed method, the parameters (X, K, ∆t) of the linear Muskingum method were optimized using the PSO algorithm, and by dividing the temporal changes in the input concentration into three areas of the beginning (the input concentration is greater than the output concentration), the peak (the maximum input and output concentrations) and the end (the output concentration is greater than the input concentration) areas, the accuracy of the calculations increased. The mentioned method was studied for different lengths (first case of x = 50 m (up) and x = 75 m (down), second case of x = 50 m (up) and x = 100 m (down), third case of x = 75 m (up) and x = 100 m (down)) and the mean relative error (MRE) of the total, peak area and the relative error of the maximum concentration using constant parameters for the first case were calculated as 7.08, 1.02, and 2.34 percent, for the second case as 7.41, 11.06 and 6.69 percent, and for the third case as 6.75, 3.59 and 5.42 percent, respectively. If three parameters of (X, K, ∆t) are used, the mentioned values improved by 31.3, 63.7 and 65.5 percent, respectively compared to the case of using constant parameters.

Annual Temporal Changes in Concentration of Total Dissolved Solid (TDS), Nitrate and Sulphate in Koyna River water, Maharashtra, India

The objective of the study is to recognize temporal changes that affect the Koyna River's water quality parameters throughout time. 52 samples of water in total were collected at weekly intervals from March 2018 to March 2019 at the Koyna River in the vicinity of Karad, Maharashtra, India, to determine the concentrations of TDS, sulphate (SO4--), and nitrate (NO3-). The average annual concentration of NO3-, SO4--, and TDS is considerably lower than the values prescribed by WHO and BIS for irrigation and drinking. Timely variations in the parameters have been recorded. Increasing patterns were observed throughout the monsoon season (June to September 2018), followed by a deceased pattern (October to December 2018), and then a remarkably high level of certain variables in January 2019. The outcomes showed that water entering the river from upstream sources, runoff from agriculture, and household and industrial sewage discharges in tributaries and the mainstream are responsible for variations in concentration that occur gradually, suddenly, and in various manners

Prolonged efficacy of cefazolin in intraosseous regional prophylaxis for total knee arthroplasty: a rabbit model study

BackgroundA novel approach known as intraosseous regional administration (IORA) has emerged as a technique for delivering prophylactic antibiotics, and it results in higher tissue concentrations around the knee. It is hypothesized that IORA of cefazolin for antibiotic prophylaxis during total knee arthroplasty will result in sustained effective levels for a longer duration. The aim of the current study was to investigate temporal changes in peri-knee cefazolin blood concentrations after IORA of cefazolin.MethodsTwelve rabbits were randomly divided into two groups, with six rabbits in each group. In control group a single intravenous bolus injection of cefazolin (10 mL, 100 mg) was administered into the marginal ear vein. In experimental groupexperimental group the same dose of cefazolin was injected into the left tibial marrow cavity after tourniquet inflation at the base of the left thigh. Blood samples were collected periodically at different timepoints, and cefazolin concentrations were determined.ResultsThe intraosseous treatment resulted in significant differences in plasma cefazolin concentrations at all timepoints. Experimental group exhibited higher plasma cefazolin concentrations than control group.ConclusionsCefazolin in intraosseous regional prophylaxis exhibits effectiveness in intraoperative antibiotic prophylaxis by maintaining concentrations above the minimum inhibitory concentration for extended durations, rather than relying solely on high concentrations.

Temporal changes in metal and arsenic concentrations in blood and feathers of tropical seabirds after one of the largest environmental disasters associated with mining

Monitoring of contaminant levels in wildlife over time is a tool for assessing the presence and persistence of environmental impacts at ecosystem, community and population levels. Tropical seabirds breeding in the Abrolhos Archipelago, 70 km off the Brazilian coast, forage in areas under the influence of the Doce River discharge. In 2015, the Fundão Dam collapsed and released ca 60 million tons of iron ore tailings into the ocean. In the present study, red-billed tropicbirds Phaethon aethereus and brown boobies Sula leucogaster breeding in Abrolhos were monitored over four years (2019–2022) for metal (Fe, Mn, Zn, Cu, Cr, Hg, Pb, Cd) and metalloid (As) concentrations in blood and feathers. Over six sampling events, metal (loid) concentrations showed strong temporal variation in both tissues. Overall, feathers showed greater element concentrations than blood, with stronger correlations between elements, especially Mn and the nonessential As, Cd, Hg and Pb. Mn is one of the major chemical markers of the Fundão Dam tailings. Metal (loid) concentrations in the tropical seabirds evaluated were above suggested threshold levels for most nonessential elements (As, Cd and Pb), especially in February 2021, when metal (loid) concentrations peaked in feathers. In this case, values were orders of magnitude higher than those observed in other sampling events. This occurred one year after a major rainy season in the Doce River basin, which increased river discharge of contaminated mud into the ocean, where contaminants are further remobilized by winds and currents, resulting in transference through the marine food web. This finding is consistent to what has been observed for other ecosystem compartments monitored in the region under the influence of the Doce River. Our findings highlight the utility of using tropical seabirds as sentinels of marine pollution, revealing strong temporal patterns in metal (loid) concentrations associated to bottom-up climatic processes.

Neuronal sensorimotor integration guiding salt concentration navigation in Caenorhabditis elegans

Animals navigate their environment by manipulating their movements and adjusting their trajectory which requires a sophisticated integration of sensory data with their current motor status. Here, we utilize the nematode Caenorhabditis elegans to explore the neural mechanisms of processing the sensory and motor information for navigation. We developed a microfluidic device which allows animals to freely move their heads while receiving temporal NaCl stimuli. We found that C. elegans regulates neck bending direction in response to temporal NaCl concentration changes in a way which is consistent with a C. elegans' navigational strategy which regulates traveling direction toward preferred NaCl concentrations. Our analysis also revealed that the activity of a neck motor neuron is significantly correlated with neck bending and activated by the decrease in NaCl concentration in a phase-dependent manner. By combining the analysis of behavioral and neural response to NaCl stimuli and optogenetic perturbation experiments, we revealed that NaCl decrease during ventral bending activates the neck motor neuron which counteracts ipsilateral bending. Simulations further suggest that this phase-dependent response of neck motor neurons can facilitate curving toward preferred salt concentrations.

Real-Time Measurement of Antiglaucoma Drugs in Porcine Eyes Using Boron-Doped Diamond Microelectrodes.

The primary treatment for glaucoma, the most common cause of intermediate vision impairment, involves administering ocular hypotensive drugs in the form of topical eye drops. Observing real-time changes in the drugs that pass through the cornea and reach the anterior chamber of the eye is crucial for improving and developing safe, reliable, and effective medical treatments. Traditional methods for measuring temporal changes in drug concentrations in the aqueous humor employ separation analyzers such as LC-MS/MS. However, this technique requires multiple measurements on the eyes of various test subjects to track changes over time with a high temporal resolution. To address this issue, we have developed a measurement method that employs boron-doped diamond (BDD) microelectrodes to monitor real-time drug concentrations in the anterior chamber of the eye. First, we confirmed the electrochemical reactivity of 13 antiglaucoma drugs in a phosphate buffer solution with a pH of 7.4. Next, we optimized the method for continuous measurement of timolol maleate (TIM), a sympathetic beta-receptor antagonist, and generated calibration curves for each BDD microelectrode using aqueous humor collected from enucleated porcine eyes. We successfully demonstrated the continuous ex vivo monitoring of TIM concentrations in the anterior chambers of these enucleated porcine eyes. The results indicate that changes in intracameral TIM concentrations can be monitored through electrochemical measurements using BDD microelectrodes. This technique holds promise for future advancements in optimizing glaucoma treatment and drug administration strategies.

Geomagnetic relative paleointensity and direction during the last 40,000 years obtained from a sediment core in the Nankai Trough

Construction of regional geomagnetic secular variation curves for the last several tens of thousands of years is important for understanding the behavior of non-dipole fields and applications to geochronology. Around Japan, secular variation records of older than 10 ka was scarce, in particular for relative paleointensity (RPI). Here, we conducted a paleomagnetic study of a sediment core covering the last ~ 40 kyr taken from a small basin in the Nankai Trough. The core consists of homogenous hemipelagic sediments except for turbidites and volcanic ashes. The age model was constructed based on seven 14C datings and two volcanic ashes. Turbidites and volcanic ashes were excluded from the construction of secular variation curves because of geologically instantaneous deposition. It was revealed that the magnetization of this core is carried largely by detrital magnetic minerals, although magnetofossils are also contained. Bulk magnetic properties show some temporal changes in magnetic concentration and grain size, but still homogeneous enough for reliable RPI estimations except for turbidites and volcanic ashes. The resultant RPI shows no correlation with the normalizer, anhysteretic remanent magnetization, of the RPI estimations or with a proxy for a magnetic grain size and/or the proportion of magnetofossils to detrital magnetic minerals. The obtained RPI record shows a long-term increasing trend since ~ 40 ka, which coincides with global stack curves. On the other hand, there are some differences in shorter timescale variations, which may reflect non-dipole fields. This study demonstrated that hemipelagic sediments in the Nankai Trough have potential for recovering high-quality RPI records when turbidites and volcanic ashes were excluded and are useful for accumulating records to construct a regional master curve.Graphical abstract

Temporal changes of 137Cs concentrations in the Far Eastern Seas: partitioning of 137Cs between overlying waters and sediments

Deep-ocean sediments, similarly to seawater, are important reservoirs of 137Cs, an anthropogenic radionuclide with a relatively long half-live found in the Earth system. To better understand the geochemical behaviour of 137Cs in the ocean, we examined the temporal changes of 137Cs activity concentrations in the overlying waters and in sediments from the Far Eastern Seas (Sea of Japan, SOJ, and Okhotsk Sea, OS) during the period of 1998–2021. The 137Cs activity levels showed exponential changes during the observed period. The decay-corrected change rates of 137Cs in deep waters of SOJ exhibited a slow increase, while 137Cs levels in seawater and sediment in OS decreased gradually. This reflects a topographical difference, as SOJ is a semi-closed sea, whereas OS receives continuously inflow of subarctic waters. It was confirmed that 137Cs released after the Fukushima Dai-ichi Nuclear Power Plant accident was rapidly transported into the deep waters of the SOJ. To elucidate the transfer processes of 137Cs from seawater to sediment, we discussed the temporal changes of the partition coefficients (Kd) of 137Cs between the overlying water and the surface sediment. In shallow areas (< 1500 m water depth), Kd values were almost constant within the sampling periods, although the temporal changes in the Kd values occurred in deeper waters (> 2500 m depth). The Kd values increased with increasing depth, which may reflect a pressure effect as a possible mechanism. These findings suggest that chemical processes may be important factors controlling the transport of 137Cs between seawater and sediment, although more complicated phenomena occurred in deep waters and sediments of the SOJ (> 3000 m depth).

Hydrodynamic Groundwater Modeling and Hydrochemical Conceptualization of the Closure Mining Area of the WuMa River Watershed of China.

The WuMa River (WMR) watershed is located in Renhuai City, Guizhou Province of China, which is a first-class tributary of the Chishui River. The geochemical investigation mainly included the determination of groundwater pH, total hardness, total dissolution solid, major cationic and anionic, and the geochemical groundwater modeling. The principal component analysis (PCA) and Gibbs model were used to analyze the pollution type and geochemical composition. The geochemical investigation results show that the cations of groundwater are dominated by Ca2+ and the anions are dominated by HCO3-; therefore, two main hydrochemical types in the study area are identified as Ca2+-Mg2+-HCO3- and Ca2+-Mg2+-SO42-. The chemical composition of groundwater in this area is mainly controlled by weathering of the carbonate rocks. The ion concentration of groundwater in the study area exhibited significant spatial variability between dry and wet seasons, while temporal changes of cationic and anionic concentrations exhibited irregularities. In PCA and FA analysis, PC1, PC2, and PC3 were extracted, which could explain 51.92, 26.98, and 12.61% of the total information, respectively. F1 explained 67.44% of the total variance, among which Ca2+, Mg2+, K+, SO42-, and Cl- contributed the most among the factors and were the main factors controlling the chemical composition of groundwater. The relative error between the measured water level and the simulated water level is less than 2%, which meets the requirements of simulation accuracy. During the simulation period of the model, a total recharge of 339.05 × 104 m3 was observed in the simulated area, primarily attributed to infiltration from rainfall. The total excretion amounted to 330.78 × 104 m3, primarily through evaporation, with a minor amount of lateral outflow. The migration pathway of pollutants in groundwater primarily follows the direction of groundwater flow while diffusing vertically. The migration range of the pollutant is in accordance with the direction of groundwater flow and extends along the larger hydraulic gradient, demonstrating consistency. The findings of this study serve as a reminder that the closure of coal mines can constitute a significant source of water pollution. Simultaneously, they offer empirical data and theoretical references for the simulation and prediction of groundwater contamination in enclosed coal mines.

Net effect of chemical erosion in a tropical basin on carbon cycle: Constraints from elemental and sulfur isotopic composition of the Mahanadi river water

Chemical erosion in river basins influence the climate by both consuming (via silicate erosion and carbon burial) and releasing (via H2SO4-mediated carbonate weathering and organic oxidation) atmospheric CO2. Net erosional effect of a basin on carbon cycle, therefore, requires precise rate assessment of all these pathways; combined data for the four processes for a given basin are sparse. In this contribution, we have quantified these process intensities for a large tropical basin (Mahanadi river) from the eastern part of India using new time-series (weekly) data for dissolved major ions and sulfur isotopes, and compiled data for rhenium concentrations and particulate carbon isotopes for the basin. The discharge-weighted silica concentrations (∼215 μM) of these samples is higher than that reported as global average for rivers (∼145 μM), indicating intense silicate erosion in the basin. The δ34S of the riverine sulfates vary between 8.8 ‰ and 17 ‰, with a discharge-weighted average of 12 ± 4 ‰ (global riverine value ∼4.4 ± 4.5‰). Temporal changes in concentrations for most of the elements (and δ34S) show relatively higher (enriched) values during lean-flow stages. Mass balance calculations involving Ca, Mg and Si values confirm that these seasonal changes are mainly due to increase (by 18 ± 9%) of groundwater supply to the stream during non-monsoon seasons. The silicate-derived cations (Catsilicate) for the Mahanadi show minimal changes during monsoon (36 ± 5%) and non-monsoon (33 ± 8%) seasons. These data correspond to a CO2 consumption rate of 2.4 ± 1.6 tC/km2/yr, which is about two times higher than that reported for global rivers. Comparison of δ34S values of riverine sulfate with its possible sources computes the relative supply of sulfates from atmospheric deposition (38%), gypsum (46%), and sulfides (16% (a lower limit)) to the river. The minimal contribution via sulfide oxidation confirms low CO2 release (0.1 ± 0.1 tC/km2/yr) in this basin through sulfuric-acid mediated carbonate weathering. Average rhenium for this river is 5 ± 3 pmol/kg. The source apportionment using S/Re and Na/Re ratios indicates that 85 ± 10% of the Re is derived through organic oxidation. The rhenium data are used to estimate the CO2 release rate (0.50 ± 0.57 tC/km2/yr) by oxidation of petrogenic carbon, which is higher than the estimated organic burial rate (0.27 ± 0.12) for the basin. The estimated four erosion rates confirm a net negative (∼ − 2.1 ± 1.7 tC/km2/yr) effect of chemical erosion in the Mahanadi basin on the CO2 budget. Low sulfide-oxidation in this supply-limited regime is possibly linked to limited exposure of fresher minerals, whereas high silicate erosion in the basin is consistent with its silicate-dominated lithology and tropical climate.

Long-Term Dynamics of Persistent Organic Pollutants in Water Bodies of the Aral Sea–Syrdarya Basin

The huge decrease in water volume in the Aral Sea, which was caused predominately by enormous water withdrawals from the Aral Sea tributaries, has changed the former world’s fourth-biggest inland lake into a new desert called Aralkum. Due to its long-term use in agriculture, persistent organic pollutants (POPs), including organochlorine pesticides (OCPs), and polychlorinated biphenyls (PCBs) play a special role in the pollution of the Aral Sea tributaries and in the Aral Sea itself. For the first time, POPs, OCPs, and PCBs were studied in the Large Aral Sea, Small Aral Sea, and the Syrdarya River. PCBs and OCPs in the collected water samples were analyzed using gas chromatography. The results of long-term and inter-annual analyses of POPs in water resources of the Kazakh part of the Aral Sea–Syrdarya Basin are presented. The analyses covered the Large and Small Aral Seas, the Syrdarya River, reservoirs, lakes of the river delta, and drainage water of the collectors from irrigation areas. The inflow to the Syrdarya River that came from the collector–drainage water was the main cause of water pollution. The pollution levels of toxic compounds, including the trends of temporal and spatial changes in pollutant concentrations, were analyzed and assessed. The latest studies from 2021 and 2022 show a decrease in pesticide concentrations by tens and hundreds of times.

Per- and polyfluoroalkyl substances (PFAS) and thyroid hormone measurements in dried blood spots and neonatal characteristics: a pilot study

BackgroundPediatric thyroid diseases have been increasing in recent years. Environmental risk factors such as exposures to chemical contaminants may play a role but are largely unexplored. Archived neonatal dried blood spots (DBS) offer an innovative approach to investigate environmental exposures and effects.ObjectiveIn this pilot study, we applied a new method for quantifying per- and polyfluoroalkyl substances (PFAS) to 18 archived DBS from babies born in California from 1985–2018 and acquired thyroid hormone measurements from newborn screening tests. Leveraging these novel data, we evaluated (1) changes in the concentrations of eight PFAS over time and (2) the relationship between PFAS concentrations, thyroid hormone concentrations, and neonatal characteristics to inform future research.MethodsPFAS concentrations in DBS were measured using ultra-high-performance liquid chromatography-mass spectrometry. Summary statistics and non-parametric Wilcoxon rank-sum and Kruskal–Wallis tests were used to evaluate temporal changes in PFAS concentrations and relationships between PFAS concentrations, thyroid hormone concentrations, and neonatal characteristics.ResultsThe concentration and detection frequencies of several PFAS (PFOA, PFOS, and PFOSA) declined over the assessment period. We observed that the timing of specimen collection in hours after birth was related to thyroid hormone but not PFAS concentrations, and that thyroid hormones were related to some PFAS concentrations (PFOA and PFOS).Impact statementThis pilot study examines the relationship between concentrations of eight per- and polyfluoroalkyl substances (PFAS), thyroid hormone levels, and neonatal characteristics in newborn dried blood spots (DBS) collected over a period of 33 years. To our knowledge, 6 of the 22 PFAS we attempted to measure have not been quantified previously in neonatal DBS, and this is the first study to examine both PFAS and thyroid hormone concentrations using DBS. This research demonstrates the feasibility of using newborn DBS for quantifying PFAS exposures in population-based studies, highlights methodological considerations in the use of thyroid hormone data for future studies using newborn DBS, and indicates potential relationships between PFAS concentrations and thyroid hormones for follow-up in future research.

Microcosm study on fate and dynamics of mangrove tannins during leaf litter leaching

BackgroundMangrove tannins can participate in wetland biogeochemical cycling. However, their fate and dynamics during leaf litter leaching have yet to be elucidated in coastal aquatic environments.MethodsBy using a simulated microcosm experiment, changes in leaf litter mass and tannin compounds, including total phenolics (TP), extractable condensed tannins (ECT), and bound condensed tannins (BCT), were examined in the litters and leachates of four common mangrove species: Kandelia obovata (Ko), Aegiceras corniculatum (Ac), Sonneratia apetala (Sa), and Avicennia marina (Am).ResultsLeaching caused a notable decline in litter mass, TP, and ECT in the leaf litter of Ko, Ac, Sa, and Am, while BCT increased significantly in Ko and Ac. Loss in foliar TP was higher than in leaf litter mass, and loss in foliar ECT was higher than in TP of Ko and Ac, but Sa showed the opposite result. The temporal changes of TP and ECT concentrations in leachates followed a similar trend, with an initial increase followed by a decrease. ECT dynamics in Ko and Ac leachates correlated with their TP concentrations, while in Sa leachate, the peak ECT occurred 72 h later than its TP peak. The leachate ECT concentrations were highest in Ac, followed by Ko, and significantly lower in Sa. The peak TP and ECT proportions in leachates accounted for 9.2–23.9% and 7.7–9.4% of the total decreases in foliar TP and ECT, respectively.ConclusionDuring the leaching process, tannins’ fate was species-specific, while the dynamics were almost similar.

Sequential Interaction of Biogenic Volatile Organic Compounds and SOAs in Urban Forests Revealed Using Toeplitz Inverse Covariance-Based Clustering and Causal Inference

Urban forests play a crucial role in both emitting and absorbing atmospheric pollutants. Understanding the ecological processes of biogenic volatile organic compounds (BVOCs) and secondary organic aerosols (SOAs) and their interactions in urban forests can help to assess how they influence air quality. Additionally, exploring the adaptation and feedback mechanisms between urban forests and their surrounding environments can identify new pollutants and potential risks in urban forests. However, the relationship between BVOC emissions and SOA formation is complex due to the influence of meteorological conditions, photochemical reactions, and other factors. This complexity makes it challenging to accurately describe this relationship. In this study, we used time-of-flight mass spectrometry and aerosol particle size spectrometry to monitor concentrations of BVOCs and particulate matter with a diameter less than 1 µm (PM1; representing SOAs) at a frequency of 10–12 times per min in an urban forest near Shanghai. We then analyzed the temporal changes in concentrations of BVOCs, SOAs, and other chemical pollutants in different periods of the day by using subsequence clustering and causal inference methods. The results showed that after using this method for diurnal segmentation, PM1 prediction accuracy was improved by 26.77%–47.51%, and the interaction rules of BVOCs and SOAs had sequential interaction characteristics. During the day, BVOCs are an important source of SOAs and have a negative feedback relationship with O3. From night to early morning, BVOCs have a positive, balanced relationship with O3, SOAs are affected by wind speed or deposition, BVOCs have no obvious relationship with O3, and SOAs are affected by temperature or humidity. This study is the first to apply Toeplitz inverse covariance-based clustering and causal inference methods for the high-frequency monitoring of BVOCs and SOAs, revealing the temporal effects and characteristics of BVOCs and SOAs and providing a scientific basis and new methods for understanding the dynamic effects of urban forest communities on the environment.

Accuracy Verification of Satellite Products and Temporal and Spatial Distribution Analysis and Prediction of the CH4 Concentration in China

In this study, the spatiotemporal variations in CH4 concentrations in China from 2003 to 2021 are investigated, and their trends are forecasted over the next decade. Based on the seventh edition standard product retrieved by the atmospheric infrared detector (AIRS) at an altitude of 500 hPa, we verified monthly CH4 products using observational data provided by the World Data Center for Greenhouse Gases (WDCGG) from six ground stations in and around China. The correlation coefficients (R values) between the two data sets ranged from 0.68 to 0.92, signifying the ability of AIRS inversion data to represent temporal and spatial changes in surface CH4 concentrations. Additionally, China was classified into three regions (steps) based on terrain, and the changes in CH4 concentrations were assessed from three perspectives: spatial distribution, interannual variation, and seasonal variation. The results revealed that the CH4 concentration decreased with elevation along a topographic gradient, with high-value areas located in the first and second steps, corresponding to the eastern Qinghai–Tibet Plateau, northern Xinjiang Uygur Autonomous Region, and Inner Mongolia Autonomous Region. Over 19 years, the average increase in CH4 concentration has ranged from 65 to 175 ppb. In addition, the CH4 concentrations were higher during summer and autumn and lower during spring and winter. Finally, a SARIMA model was used to predict the near-surface CH4 concentration trend in China over the next ten years, which indicated a continued seasonal increase.

The Within-Individual Effects of U.S. Immigration on Individual-Level Offending During Adolescence and Early Adulthood

Objectives: Prior contextual-level studies suggest that individuals who reside in areas with higher concentrations of foreign-born residents engage in less crime and delinquency. Yet, this work has relied on either cross-sectional models or longitudinal data with only baseline measurements of immigration, which tells us little about whether temporal changes in immigrant concentration affect changes in individual-level offending. We addressed this shortcoming by conducting a contextual-level study that uses a within-individual research design. Methods: Using public and restricted data from the National Longitudinal Survey of Youth 1997 and U.S. Census data, we employed Bayesian random-effects models to examine the within-individual associations between the percentage of the population that is foreign-born in respondents’ county of residence and two indicators of criminal offending during adolescence and early adulthood. Results: Findings indicated that percent foreign-born was associated with subsequent reductions in criminal arrest but not self-reported offending. Moreover, we found that these effects were similar regardless of whether respondents moved or remained in place over time. Finally, for self-reported offending, the effects of percent foreign-born were stronger for first-generation immigrants, but for arrest, they were similar across generation. Conclusions: Immigrant concentration is a time-varying phenomenon that has the potential to reduce individual-level offending.