Occurrence and fate of current-use pesticides in Chinese forest soils.

Pesticides play a crucial role in securing global food production to meet increasing demands. However, because of their pervasive use, they are now ubiquitous environmental pollutants that have adverse effects on both ecosystems and human health. In this study, the environmental occurrence and fate of 16 current-use pesticides (CUPs) were investigated in 93 forest soil samples obtained from 11 distinct mountains in China. The concentrations of the target pesticides ranged from 0.36 to 55 ng/g dry weight. Cypermethrin, dicofol, chlorpyrifos, chlorothalonil, and trifluralin were the most frequently detected CUPs. The CUP concentrations were generally higher in the O-horizon than in the A-horizon. Chlorpyrifos, chlorothalonil, and dicofol were detected in most deep layers in soil profiles from three mountains selected to represent distinct climate zones. No clear altitudinal trend in organic carbon-normalized concentrations of CUPs was observed in the O- or A-horizons within individual mountains. A negative correlation was noted between the CUP concentrations and the altitudes across all sampling sites. This indicated that proximity to emission sources was a key factor affecting the spatial distribution of CUPs in mountain forest soil on a national scale. The ecological risk assessment showed that dicofol and cypermethrin pose potential risks to earthworms. This study emphasizes the importance of source control when setting management strategies for CUPs.

Mapping the Contribution of Biomass Burning to Persistent Organic Pollutants in the Air of the Indo-China Peninsula Based on a Passive Air Monitoring Network.

Biomass burning (BB) is an important source of atmospheric persistent organic pollutants (POPs) across the world. However, there are few field-based regional studies regarding the POPs released from BB. Due to the current limitations of emission factors and satellites, the contribution of BB to airborne POPs is still not well understood. In this study, with the simultaneous monitoring of BB biomarkers and POPs based on polyurethane foam-based passive air sampling technique, we mapped the contribution of BB to polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in the Indo-China Peninsula. Spearman correlations between levoglucosan and 16 PCBs (rs = 0.264-0.767, p < 0.05) and 2 OCPs (rs = 0.250-0.328, p < 0.05) confirmed that BB may facilitate POP emissions. Source apportionment indicated that BB contributed 9.3% to the total PCB and OCP mass. The high contribution of positive matrix factorization-resolved BB to PCBs and OCPs was almost consistent with their concentration distributions in the open BB season but not completely consistent with those in the pre-monsoon and/or monsoon seasons. Their contribution distributions may reflect the use history and geographic distribution in secondary sources of POPs. The field-based contribution dataset of BB to POPs is significant in improving regional BB emission inventories and model prediction.

Provenance of Aerosol Black Carbon over Northeast Indian Ocean and South China Sea and Implications for Oceanic Black Carbon Cycling.

Aerosol black carbon (BC) is a short-lived climate pollutant. The poorly constrained provenance of tropical marine aerosol BC hinders the mechanistic understanding of extreme climate events and oceanic carbon cycling. Here, we collected PM2.5 samples during research cruise NORC2016-10 through South China Sea (SCS) and Northeast Indian Ocean (NEIO) and measured the dual-carbon isotope compositions (δ13C-Δ14C) of BC using hydrogen pyrolysis technique. Aerosol BC exhibits six different δ13C-Δ14C isotopic spaces (i.e., isotope provinces). Liquid fossil fuel combustion, from shipping emissions and adjacent land, is the predominant source of BC over isotope provinces "SCS close to Chinese Mainland" (53.5%), "Malacca Strait" (53.4%), and "Open NEIO" (40.7%). C3 biomass burning is the major contributor to BC over isotope provinces "NEIO close to Southeast Asia" (55.8%), "Open NEIO" (41.3%), and "Open SCS" (40.0%). Coal combustion and C4 biomass burning show higher contributions to BC over "Sunda Strait" and "Open SCS" than the others. Overall, NEIO near the Bay of Bengal, Malacca Strait, and north SCS are three hot spots of fossil fuel-derived BC; the first two areas are also hot spots of biomass-derived BC. The comparable δ13C-Δ14C between BC in aerosol and dissolved BC in surface seawater may suggest atmospheric BC deposition as a potential source of oceanic dissolved BC.

Aquatic environmental fates and risks of benzotriazoles, benzothiazoles, and p-phenylenediamines in a catchment providing water to a megacity of China.

Wearing of vehicle parts could release many chemical additives into the environment, such as benzotriazoles (BTRs), benzothiazoles (BTHs), and p-phenylenediamines (PPDs), which are potentially toxic to wildlife and humans. This study investigated the occurrence, source, and risks of BTRs, BTHs, and PPDs in a source catchment providing water to Guangzhou, a megacity in South China, covering groundwater, surface water, and stormwater. The results showed that BTRs and BTHs were predominant in surface water and groundwater. Unexpectedly, the BTR and BTH concentrations were lower in surface water than groundwater in a third of the paired samples. For the first time, 6PPD-quinone, a toxic ozonation product of N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine (6PPD), was extensively detected in source waters. Stormwater decreased the BTR concentrations but increased the 6PPD-quinone concentrations in surface water owing to their affiliation to suspended particles. From natural to urban segments of Liuxi river, a downstream increasing trend in BTR and BTH concentrations was observed, confirming that they are indicative of urban anthropogenic activities. Strong correlations between industrial activities and BTR or BTH concentrations in surface water indicated that industrial activities were their main sources. Six compounds were prioritized as potentially persistent, mobile, and toxic (PMT) chemicals, combing our monitoring results and REACH criterion. This study improves our understanding of the environmental fates and risks of water-soluble tire-wear chemicals, which provides important information for chemical management, and indicates attention should be paid to the risk posed by 6PPD-quinone in the source water.

Synthesis and antitumor activity of erysolin and its metabolites.

Erysolin and its two metabolites which were found in blood, ERY-GSH and ERY-NAC, were synthesized by alkylation, amination, isothiocyanation and oxidation reactions from 1-bromo-4-chlorobutane and sodium methyl mercaptide. The reaction temperature, time, feed ratios and purification method were also optimized. The synthesis method was simple, green, safe and low-cost. Erysolin, ERY-GSH and ERY-NAC showed good antitumor activities against MCF-7, HeLa, HepG2, A549 and SW480 cells, which suggested that the antitumor mechanism of erysolin can also be clarified from its metabolites in addition to itself.

A GmSIN1/GmNCED3s/GmRbohBs Feed-Forward Loop Acts as a Signal Amplifier That Regulates Root Growth in Soybean Exposed to Salt Stress.

Abscisic acid (ABA) and reactive oxygen species (ROS) act as key signaling molecules in the plant response to salt stress; however, how these signals are transduced and amplified remains unclear. Here, a soybean (Glycine max) salinity-induced NAM/ATAF1/2/CUC2 (NAC) transcription factor encoded by SALT INDUCED NAC1 (GmSIN1) was shown to be a key component of this process. Overexpression of GmSIN1 in soybean promoted root growth and salt tolerance and increased yield under salt stress; RNA interference-mediated knockdown of GmSIN1 had the opposite effect. The rapid induction of GmSIN1 in response to salinity required ABA and ROS, and the effect of GmSIN1 on root elongation and salt tolerance was achieved by boosting cellular ABA and ROS contents. GmSIN1 upregulated 9-cis-epoxycarotenoid dioxygenase coding genes in soybean (GmNCED3s, associated with ABA synthesis) and Respiratory burst oxidase homolog B genes in soybean (GmRbohBs, associated with ROS generation) by binding to their promoters at a site that has not been described to date. Together, GmSIN1, GmNCED3s, and GmRbohBs constitute a positive feed-forward system that enables the rapid accumulation of ABA and ROS, effectively amplifying the initial salt stress signal. These findings suggest that the combined modulation of ABA and ROS contents enhances soybean salt tolerance.

A simple, efficient route to modify the properties of epoxy dynamic polymer networks.

A simple and efficient strategy to modify epoxy dynamic polymer networks (DPNs) is presented. The introduction of the flexible epoxidized form of naturally occurring soybean oil (ESO) into epoxy DPNs markedly improves their mechanical properties, stress relaxation rate and malleability. Specifically, at 7.5 wt% ESO loading, the elongation at break of the as-produced epoxy-ESO DPNs was increased from 10% to 108%, the stress relaxation time decreased from 6100 s to 2570 s at 120 °C, and the reprocessing temperature was reduced by 26 °C, which is advantageous for expanding the scope of applications of these materials, especially for reducing the energy consumption during reprocessing. At this composition, the epoxy-ESO DPNs also showed excellent self-healing, welding and chemical degradation properties. This work provides a novel pathway to fabricate epoxy-based DPNs with high performance in an energy-conserving manner.

Probing Legacy and Alternative Flame Retardants in the Air of Chinese Cities.

An increasing number of alternative flame retardants (FRs) are being introduced, following the international bans on the use of polybrominated diphenyl ether (PBDE) commercial mixtures. FRs' production capacity has shifted from developed countries to developing countries, with China being the world's largest producer and consumer of FRs. These chemicals are also imported with e-waste to China. Therefore, it is important to understand the current status of regulated brominated FRs, their phase-out in China, and their replacement by alternatives. In this study, a broad suite of legacy and alternative FRs, including eight PBDEs, six novel brominated FRs (NBFRs), two dechlorane plus variants (DPS), and 12 organophosphate FRs (OPFRs) were evaluated in the air of 10 large Chinese cities in 2018. OPFRs are the most prevalent FRs in China, exhibiting a wide range of 1-612 ng/m3, which is several orders of magnitude higher than PBDEs (1-1827 pg/m3) and NBFRs (1-1428 pg/m3). BDE 209 and DBDPE are the most abundant compounds in brominated FRs (>80%). The North China Plain (NCP, excluding Beijing), Guangzhou, and Lanzhou appear to be three hotspots, although with different FR patterns. From 2013/2014 to 2018, levels of PBDEs, NBFRs, and DPs have significantly decreased, while that of OPFRs has increased by 1 order of magnitude. Gas-particle partitioning analysis showed that FRs could have not reached equilibrium, and the steady-state model is better suited for FRs with a higher log KOA (>13). To facilitate a more accurate FR assessment in fine particles, we suggest that, in addition to the conventional volumetric concentration (pg/m3), the mass-normalized concentration (pg/g PM2.5) could also be used.

DDT, Chlordane, and Hexachlorobenzene in the Air of the Pearl River Delta Revisited: A Tale of Source, History, and Monsoon.

Although organochlorine pesticides (OCPs) have been banned for more than three decades, their concentrations have only decreased gradually. This may be largely attributable to their environmental persistence, illegal application, and exemption usage. This study assessed the historic and current regional context for dichlorodiphenyltrichloroethane (DDT), chlordane, and hexachlorobenzene (HCB), which were added to the Stockholm Convention in 2001. An air sampling campaign was carried out in 2018 in nine cities of the Pearl River Delta (PRD), where the historical OCP application was the most intensive in China. Different seasonalities were observed: DDT exhibited higher concentrations in summer than in winter; chlordane showed less seasonal variation, whereas HCB was higher in winter. The unique coupling of summer monsoon with DDT-infused paint usage, winter monsoon with HCB-combustion emission, and local chlordane emission jointly presents a dynamic picture of these OCPs in the PRD air. We used the BETR Global model to back-calculate annual local emissions, which accounted for insignificant contributions to the nationally documented production (<1‰). Local emissions were the main sources of p,p'-DDT and chlordane, while ocean sources were limited (<4%). This study shows that geographic-anthropogenic factors, including source, history, and air circulation pattern, combine to affect the regional fate of OCP compounds.

Design, synthesis and evaluation of 1-benzyl-1H-imidazole-5-carboxamide derivatives as potent TGR5 agonists.

TGR5 is emerging as an important and promising target for the treatment of diabetes, obesity and other metabolic syndromes. A series of novel 1-benzyl-1H-imidazole-5-carboxamide derivatives was designed, synthesized and evaluated in vitro and in vivo. The most potent compounds 19d and 19e exhibited excellent agonistic activities against hTGR5, which was superior to those of the reference drugs INT-777 and LCA. In addition, compounds 19d and 19e exhibited good selectivity against FXR and presented significant glucose-lowering effects in vivo. Compound 19d could stimulate GLP-1 secretion by activating of TGR5.

EVA1A Plays an Important Role by Regulating Autophagy in Physiological and Pathological Processes.

Eva-1 homolog A (EVA1A) is regarded as TMEM166 (transmembrane protein 166) or FAM176A (family with sequence similarity 176) and a lysosome and endoplasmic reticulum-associated protein involved in regulating autophagy and apoptosis. EVA1A regulates embryonic neurogenesis, cardiac remodeling, islet alpha-cell functions, acute liver failure, and hepatitis B virus replication. However, the related mechanisms are not fully clear. Autophagy is a process in which cells transfer pathogens, abnormal proteins and organelles to lysosomes for degradation. It plays an important role in various physiological and pathological processes, including cancer, aging, neurodegeneration, infection, heart disease, development, cell differentiation and nutritional starvation. Recently, there are many studies on the important role of EVA1A in many physiological and pathological processes by regulating autophagy. However, the related molecular mechanisms need further study. Therefore, we summarize the above-mentioned researches about the role of EVA1A in physiological and pathological processes through regulating autophagy in order to provide theoretical basis for future researches.

Evidence for Major Contributions of Unintentionally Produced PCBs in the Air of China: Implications for the National Source Inventory.

Polychlorinated biphenyls (PCBs) were not widely manufactured or used in China before they became the subject of international bans on production. Recent work has shown that they have reached China associated with imported wastes and that there are considerable unintentional sources of PCBs that have only recently been identified. As such, it was hypothesized that the source inventory and profile of PCBs may be different or unique in China, compared to countries where they were widely used and which have been widely studied. For the first time in this study, we undertook a complete analysis of 209 PCB congeners and assessed the contribution of unintentionally produced PCBs (UP-PCBs) in the atmosphere of China, using polyurethane foam passive air samplers (PUF-PAS) deployed across a wide range of Chinese locations. ∑209 PCBs ranged from 9 to 6856 pg/m3 (median: 95 pg/m3) during three deployments in 2016-2017. PCB 11 was one of the most detected congeners, contributing 33 ± 19% to ∑209 PCBs. The main sources to airborne PCBs in China were estimated and ranked as pigment/painting (34%), metallurgical industry/combustion (31%), e-waste (23%), and petrochemical/plastic industry (6%). For typical Aroclor-PCBs, e-waste sources were dominated (>50%). Results from our study indicate that UP-PCBs have become the controlling source in the atmosphere of China, and an effective control strategy is urgently needed to mitigate emissions from multiple industrial sources.

Strategies for the development of highly selective cytochrome P450 inhibitors: Several CYP targets in current research.

Cytochromes P450 (CYPs) play an important role in the metabolism of endogenic and xenobiotic substances, especially drugs. In addition, many CYPs may serve as targets for disease treatment. However, due to the presence of a common heme, the hydrophobicity of the CYP binding cavity, and the high homology within the binding pocket, most CYP inhibitors lack selectivity, which often leads to drug-drug interactions. Therefore, it is meaningful to develop highly selective CYP inhibitors. In this review, we summarize some of the strategies that have been used to develop highly selective CYP inhibitors, such as the weakening of the heme-binding group interaction, reduction of molecular lipophilicity and introduction of small structural changes within compounds.

Design, synthesis and evaluation of biphenyl imidazole analogues as potent antifungal agents.

To further explore the structure activity relationships (SARs) of our previously discovered antifungal lead compound (1), a series of biphenyl imidazole analogues were designed, synthesized and evaluated for their in vitro antifungal activity. Many of the synthesized compounds showed excellent activity against Candida albicans and Candida tropicalis. Among these compounds, 2-F substituted analogue 12m displayed the most remarkable in vitro activity against C. albicans, C. neoformans, A. fumigatus and fluconazole-resistant C. alb. strains, which is superior or comparable to the activity of the reference drugs fluconazole and itraconazole. Notably, the compound 12m exhibited low inhibition profiles for various human cytochrome P450 isoforms and showed low toxicity to mammalian A549 cells and U87 cells. The SARs and binding mode established in this study will be useful for further lead optimization.

High Abundance of Unintentionally Produced Tetrachlorobiphenyls (PCB47/48/75, 51, and 68) in the Atmosphere at a Regional Background Site in East China.

Although polychlorinated biphenyls (PCBs) have been banned for several decades, they are still detected with elevated levels due to their unintentional production from combustion and industrial thermal processes (UP-PCBs). To investigate the composition and current levels of UP-PCBs and understand which sources are controlling PCB burdens in ambient atmosphere, air samples were collected from August 2012 to August 2015 at a background site in east China. An unexpected high abundance of PCB47+48+75 was observed to be the predominant congener with an average concentration of 786 ± 637 pg/m3. It accounted for 48 ± 16% of ΣPCBs, followed by PCB51 (10 ± 4%), PCB11 (8 ± 6%), and PCB68 (7 ± 3%). Seasonal variations with high levels in summer and lowest levels in winter were observed for PCB47+48+75, 51, and 68. These tetrachlorobiphenyl congeners were strongly correlated with temperature ( r2 > 0.7), suggesting the control of temperature-dependent volatilization processes from contaminated surfaces. The decreased occurrence of PCB47+48+75, 51, and 68 in commercial products and their negative correlations (| r| < 0.35) with polycyclic aromatic hydrocarbon (PAHs) and weak correlation with other PCB congeners suggested unique unintentional sources that differ from combustion and industrial thermal processes or pigment, such as the use of polymer sealant, for PCB47+48+75, 51, and 68 in the ambient air.

Modeling the Time-Variant Dietary Exposure of PCBs in China over the Period 1930 to 2100.

This study aimed for the first time to reconstruct historical exposure profiles for PCBs to the Chinese population, by examining the combined effect of changing temporal emissions and dietary transition. A long-term (1930-2100) dynamic simulation of human exposure using realistic emission scenarios, including primary emissions, unintentional emissions, and emissions from e-waste, combined with dietary transition trends was conducted by a multimedia fate model (BETR-Global) linked to a bioaccumulation model (ACC-HUMAN). The model predicted an approximate 30-year delay of peak body burden for PCB-153 in a 30-year-old Chinese female, compared to their European counterpart. This was mainly attributed to a combination of change in diet and divergent emission patterns in China. A fish-based diet was predicted to result in up to 8 times higher body burden than a vegetable-based diet (2010-2100). During the production period, a worst-case scenario assuming only consumption of imported food from a region with more extensive production and usage of PCBs would result in up to 4 times higher body burden compared to consumption of only locally produced food. However, such differences gradually diminished after cessation of production. Therefore, emission reductions in China alone may not be sufficient to protect human health from PCB-like chemicals, particularly during the period of mass production. The results from this study illustrate that human exposure is also likely to be dictated by inflows of PCBs via the environment, waste, and food.

Using Polyurethane Foam-Based Passive Air Sampling Technique to Monitor Monosaccharides at a Regional Scale.

Monosaccharides are important tracers of pollution aerosol from biomass burning. Air sampling of monosaccharides is often conducted using active samplers. However, applicability of sampling monosaccharides using polyurethane foam passive air samplers (PUF-PASs) has not been investigated, since passive air samplers are often applied to monitor semivolatile organic contaminants in large scale and remote area. Our study successfully collected atmospheric monosaccharides using PUF-PASs, providing a valuable tool for monosaccharides sampling. PUF-PAS sampling rates for individual monosaccharides were calibrated using an active sampler for 92 days, and were 1.1, 1.5, and 1.1 m3/d for levoglucosan, mannosan, and galactosan, respectively. Degradation of monosaccharides in PUF-PAS was demonstrated to be negligible by spike test of 13C-labeled levoglucosan. Furthermore, passive sampling was carried out at 11 sites in the Pearl River Delta of Southern China from January to April and July to September of 2015. Monosaccharide concentrations derived from PUF-PASs were comparable with the reported data obtained by active sampling, demonstrating that the PUF-PAS approach is valid for monosaccharides monitoring. On the basis of our approach, we found that there is a clear correlation between the monosaccharide concentrations and the MODIS fire activities during January-April.

Design, synthesis and evaluation of benzoheterocycle analogues as potent antifungal agents targeting CYP51.

To further enhance the anti-Aspergillus efficacy of our previously discovered antifungal lead compound 1, a series of benzoheterocycle analogues were designed, synthesized and evaluated for their in vitro antifungal activity. The most promising compounds 13s and 14a exhibited excellent antifungal activity against C. albicans, C. neoformans, A. fumigatus and fluconazole-resistant C. albicans strains, that was superior or comparable to those of the reference drugs fluconazole and voriconazole. GC-MS analyses suggested that the novel compound 13s might have a similar mechanism to fluconazole by inhibiting fungal lanosterol 14α-demethylase (CYP51). Furthermore, compounds 13s and 14a exhibited low inhibition profiles for various human cytochrome P450 isoforms as well as excellent blood plasma stability.

A User-Adaptive Algorithm for Activity Recognition Based on K-Means Clustering, Local Outlier Factor, and Multivariate Gaussian Distribution.

Mobile activity recognition is significant to the development of human-centric pervasive applications including elderly care, personalized recommendations, etc. Nevertheless, the distribution of inertial sensor data can be influenced to a great extent by varying users. This means that the performance of an activity recognition classifier trained by one user’s dataset will degenerate when transferred to others. In this study, we focus on building a personalized classifier to detect four categories of human activities: light intensity activity, moderate intensity activity, vigorous intensity activity, and fall. In order to solve the problem caused by different distributions of inertial sensor signals, a user-adaptive algorithm based on K-Means clustering, local outlier factor (LOF), and multivariate Gaussian distribution (MGD) is proposed. To automatically cluster and annotate a specific user’s activity data, an improved K-Means algorithm with a novel initialization method is designed. By quantifying the samples’ informative degree in a labeled individual dataset, the most profitable samples can be selected for activity recognition model adaption. Through experiments, we conclude that our proposed models can adapt to new users with good recognition performance.

Long-Term Temporal Trends of Polychlorinated Biphenyls and Their Controlling Sources in China.

Polychlorinated biphenyls (PCBs) are industrial organic contaminants identified as persistent, bioaccumulative, toxic (PBT), and subject to long-range transport (LRT) with global scale significance. This study focuses on a reconstruction and prediction for China of long-term emission trends of intentionally and unintentionally produced (UP) ∑7PCBs (UP-PCBs, from the manufacture of steel, cement and sinter iron) and their re-emissions from secondary sources (e.g., soils and vegetation) using a dynamic fate model (BETR-Global). Contemporary emission estimates combined with predictions from the multimedia fate model suggest that primary sources still dominate, although unintentional sources are predicted to become a main contributor from 2035 for PCB-28. Imported e-waste is predicted to play an increasing role until 2020-2030 on a national scale due to the decline of intentionally produced (IP) emissions. Hypothetical emission scenarios suggest that China could become a potential source to neighboring regions with a net output of ∼0.4 t year-1 by around 2050. However, future emission scenarios and hence model results will be dictated by the efficiency of control measures.