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.

Targeted protein degradation in hematologic malignancies: latest updates from the 2023 ASH annual meeting.

Protein degraders, emerging as a novel class of therapeutic agents, have gained widespread attention due to their advantages. They have several advantages over traditional small molecule inhibitors, including high target selectivity and ability to target "undruggable" targets and overcome inhibitor drug resistance. Tremendous research and development efforts and massive investment have resulted in rapid advancement of protein degrader drug discovery in recent years. Here, we overview the latest clinical and preclinical updates on protein degraders presented at the 2023 ASH Annual Meeting.

Molecular signatures and formation mechanisms of water-soluble chromophores in particulate matter from Karachi in Pakistan.

Excitation-emission matrix (EEM) fluorescence spectroscopy is a widely-used method for characterizing the chemical components of brown carbon (BrC). However, the molecular basics and formation mechanisms of chromophores, which are decomposed by parallel factor (PARAFAC) analysis, are not yet fully understood. In this study, we characterized the water-soluble organic carbon (WSOC) in aerosols collected from Karachi, Pakistan, using EEM spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). We identified three PARAFAC components, including two humic-like components (C1 and C2) and one phenolic-like species (C3). We determined the molecular families associated with each component by performing Spearman correlation analysis between FT-ICR MS peaks and PARAFAC component intensities. We found that the C1 and C2 components were associated with nitrogen-enriched compounds, where C2 with the longest emission wavelength exhibited a higher level of aromaticity, N content, and oxygenation than C1. The C3 associated formulas have fewer nitrogen-containing species, a lower unsaturation degree, and a lower oxidation state. An oxidation pathway was identified as an important process in the formation of C1 and C2 components at the molecular level, particularly for the assigned CHON compounds associated with the gas-phase oxidation process, despite their diverse precursor types. Numerous C2 formulas were found in the "potential BrC" region and overlapped with the BrC-associated formulas. It can be inferred that the compounds that fluoresce C2 contributed considerably to the light absorption of BrC. These findings are essential for future studies utilizing the EEM-PARAFAC method to explore the sources, processes, and compositions of atmospheric BrC.

Benzene polycarboxylic acids as molecular markers of black carbon: Progresses and challenges.

Black carbon (BC) is generated as a result of the pyrolysis of biomass and fossil fuels. Different approaches have been taken to analyse BC in the environment, including thermal, optical and chemical methods. The chemical approach which uses benzene polycarboxylic acids (BPCAs) as molecular markers of BC has gained popularity within the scientific community recently. These pyrogenic molecular markers can be used to reconstruct ancient fire history and human presence. Here we review the development of the BPCA protocols for the analysis of BC and the previous studies that have used these methods. Additionally, this review explores the biogeochemical factors that influence the content and composition of BPCAs, which in turn affect the sources attributed to BC. These factors include the generation temperature of char, photodegradation, biodegradation and the interference of non-pyrogenic organic matter (OM) in BPCA-BC analysis. Different combustion temperatures can yield charred BC with varying degrees of aromatic condensation throughout the BC continuum, while aged soot-BC undergoes photochemical degradation, causing the loss of its original condensed aromatic structure. Photodegradation reduces the degree of BC condensation by preferentially breaking down the most condensed forms, whereas biodegradation primarily mineralizes the smaller and more biolabile BC. Non-pyrogenic sources, such as humic acids (HAs), have been found to contribute up to 25% of BPCA-BC in soil, and their presence can lead to overestimations of BC. Future research should focus on calibrating contemporary BPCA protocols using known reference materials and investigating the role of non-pyrogenic OM in BPCA-BC analysis.

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.

Characteristics of dissolved black carbon in riverine surface microlayer.

Black carbon (BC) is produced by the incomplete combustion of biomass and fossil fuels. The dissolved form of BC (DBC), which is transported through rivers into the oceans, is of great significance for the carbon cycling on the planet due to its refractory features. However, the characteristics and sources of DBC in riverine water are poorly constrained. Here, we analyzed DBC contents and stable carbon isotope (δ13C) signatures in surface microlayer (SML) from the upper, middle and lower reaches of Pearl River (PR) in the first study of its kind. The DBC contents (100.9 to 166.6 µg L-1) in SML were lower than the global average for riverine water following a trend of upper > middle > lower reaches in PR. The molecular markers of DBC (BPCAs) and their δ13C values showed no statistical differences between the sampling sites (p > 0.05), suggesting biomass burning as the dominant source.

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.

Regional monitoring of biomass burning using passive air sampling technique reveals the importance of MODIS unresolved fires.

Field-based sampling can provide more accurate evaluation than MODIS in regional biomass burning (BB) emissions given the limitations of MODIS on unresolved fires. Polyurethane foam-based passive air samplers (PUF-PASs) are a promising tool for collecting atmospheric monosaccharides. Here, we deployed PUF-PASs to monitor monosaccharides and other BB-related biomarkers and presented a dataset of 31 atmospheric BB-related biomarkers in the Indo-China Peninsula (ICP) and Southwest China. The peak concentrations of monosaccharides in the ICP occurred before monsoon season. The highest concentrations were in the eastern Mekong plain, while the lowest were along the eastern coast. BB-related biomarkers displayed elevated concentrations after April, particularly in the monsoon season; however, fewer active fires were recorded by MODIS. This revealed the importance of MODIS unresolved fires (e.g., indoor biofuel combustion, small-scale BB incidents, and charcoal fires) to the regional atmosphere. The PAS derived levoglucosan concentrations indicated that, with the inclusion of MODIS unresolved fires, the estimated top-down emissions of PM (4194-4974 Gg/yr), OC (1234-1719 Gg/yr) and EC (52-384 Gg/yr) would be higher than previous bottom-up estimations in the ICP. Future studies on these MODIS unresolved fires and regional monitoring data of BB are vital for improving the modeling of regional BB emissions.

Large contribution of fossil-derived components to aqueous secondary organic aerosols in China.

Incomplete understanding of the sources of secondary organic aerosol (SOA) leads to large uncertainty in both air quality management and in climate change assessment. Chemical reactions occurring in the atmospheric aqueous phase represent an important source of SOA mass, yet, the effects of anthropogenic emissions on the aqueous SOA (aqSOA) are not well constrained. Here we use compound-specific dual-carbon isotopic fingerprints (δ13C and Δ14C) of dominant aqSOA molecules, such as oxalic acid, to track the precursor sources and formation mechanisms of aqSOA. Substantial stable carbon isotope fractionation of aqSOA molecules provides robust evidence for extensive aqueous-phase processing. Contrary to the paradigm that these aqSOA compounds are largely biogenic, radiocarbon-based source apportionments show that fossil precursors produced over one-half of the aqSOA molecules. Large fractions of fossil-derived aqSOA contribute substantially to the total water-soluble organic aerosol load and hence impact projections of both air quality and anthropogenic radiative forcing. Our findings reveal the importance of fossil emissions for aqSOA with effects on climate and air quality.

Oxidative potential of solvent-extractable organic matter of ambient total suspended particulate in Bangkok, Thailand.

Oxidative stress is a key mechanism by which ambient particulate matter induces adverse health effects. Most studies have focused on the oxidative potential (OP) of water-soluble constituents, while there has been limited work on the OP of solvent-extractable organic matter (EOM OP). In this study, the EOM OP of ambient total suspended particulate (TSP) from Bangkok, Thailand, was determined using the dithiothreitol (DTT) assay. Positive matrix factorization (PMF), combined with chemical analysis of molecular markers, was employed to apportion the contributions of various emission sources to EOM OP. The volume-normalized OP initially increased with organic carbon (OC) concentration and plateaued gradually, while the mass-normalized OP fitted well with OC concentration using a power function. Fossil fuel combustion (62%) and plastic waste burning (23%) were the major contributors to EOM OP, while biomass burning demonstrated only a limited contribution. EOM OP correlated well with each group of polycyclic aromatic hydrocarbons (PAHs), suggesting that secondary formation of quinones associated with fossil fuel combustion and plastic waste burning could be an important pathway of TSP toxicity. This study underscores the importance of considering different emission sources when evaluating potential health impacts and the implementation of air pollution regulations.

Characterization of airborne PAHs and metals associated with PM10 fractions collected from an urban area of Sri Lanka and the impact on airway epithelial cells.

Airborne particulate matter (PM), polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) are significant contributors leading to many human health issues. Thus, this study was designed to perform chemical analysis and biological impact of airborne particulate matter 10 (PM10) in the World heritage City of Kandy City in Sri Lanka. 12 priority PAHs and 34 metals, including 10 highly toxic HMs were quantified. The biological effects of organic extracts were assayed using an in vitro primary porcine airway epithelial cell culture model. Cytotoxicity, DNA damage, and gene expressions of selected inflammatory and cancer-related genes were also assessed. Results showed that the total PAHs ranged from 3.062 to 36.887 ng/m3. The metals were dominated by Na > Ca > Mg > Al > K > Fe > Ti, while a few toxic HMs were much higher in the air than the existing ambient air quality standards. In the bioassays, a significant cytotoxicity (p < 0.05) was observed at 300 µg/mL treatment, and significant (p < 0.05) DNA damages were noted in all treatment groups. All genes assessed were found to be significantly up-regulated (p < 0.05) after 24 h of exposure and after 48 h, only TGF-ß1 and p53 did not significantly up-regulate (p < 0.05). These findings confirm that the Kandy city air contains potential carcinogenic and mutagenic compounds and thus, exposure to Kandy air may increase the health risks and respiratory tract-related anomalies.

Development of a novel pyroptosis-related LncRNA signature with multiple significance in acute myeloid leukemia.

Background: Pyroptosis, a programmed cell death (PCD) with highly inflammatory form, has been recently found to be associated with the origin of hematopoietic malignancies. Long noncoding RNA (lncRNA) had emerged as an essential mediator to regulate gene expression and been involved in oncogenesis. However, the roles of pyroptosis-related lncRNA (PRlncRNA) in acute myeloid leukemia (AML) have not yet been completely clarified. Methods: We collected AML datasets from public databases to obtain PRlncRNA associated with survival and constructed a PRlncRNA signature using Lasso-Cox regression analysis. Subsequently, we employed RT-PCR to confirm its expression difference and internal training to further verify its reliability. Next, AML patients were classified into two subgroups by the median risk score. Finally, the differences between two groups in immune infiltration, enrichment analysis and drug sensitivity were further explored. Results: A PRlncRNA signature and an effective nomogram combined with clinicopathological variables to predict the prognosis of AML were constructed. The internal validations showed that the PRlncRNA risk score model was an accurate and productive indicator to predict the outcome of AML. Furthermore, this study indicated that higher inflammatory cell and immunosuppressive cells, and less sensitive to conventional chemotherapy drugs were highlighted in the high-risk group. Conclusion: Through comprehensive analysis of PRlncRNA model, our study may offer a valuable basis for future researches in targeting pyroptosis and tumor microenvironment (TME) and provide new measures for prevention and treatment in AML.

Polycyclic Aromatic Carbon: A Key Fraction Determining the Light Absorption Properties of Methanol-Soluble Brown Carbon of Open Biomass Burning Aerosols.

The composition and radiative forcing of light-absorbing brown carbon (BrC) aerosol remain poorly understood. Polycyclic aromatics (PAs) are BrC chromophores with fused benzene rings. Understanding the occurrence and significance of PAs in BrC is challenging due to a lack of standards for many PAs. In this study, we quantified polycyclic aromatic carbon (PAC), defined as the carbon of fused benzene rings, based on molecular markers (benzene polycarboxylic acids, BPCAs). Open biomass burning aerosols (OBBAs) of 22 rainforest plants were successively extracted with water and methanol for the analysis of water- and methanol-soluble PAC (WPAC and MPAC, respectively). PAC is an important fraction of water- and methanol-soluble organic carbon (WSOC and MSOC, respectively). WPAC/WSOC ranged from 0.03 to 0.18, and MPAC/MSOC was even higher (range: 0.16-0.80). The priority polycyclic aromatic hydrocarbons contributed less than 1% of MPAC. The mass absorption efficiency (MAE) of MSOC showed a strong linear correlation with MPAC/MSOC (r = 0.60-0.95, p < 0.01). The absorption Ångström exponent (AAE) of methanol-soluble BrC showed a strong linear correlation with the degree of aromatic condensation of MPAC, which was described by the average number of carboxylic groups of BPCA (r = -0.79, p < 0.01). This result suggested that PAC was a key fraction determining the light absorption properties (i.e., light absorptivity and wavelength dependence) of methanol-soluble BrC in OBBAs.

Distribution of black carbon and PAHs in sediments of Peninsular Malaysia.

Concentrations, sources and interactions between black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs) were investigated in 42 sediment samples collected from riverine, coastal and shelf areas in Peninsular Malaysia. The concentrations of BC measured by benzene polycarboxylic acid (BPCA) method and PAHs showed broad spatial variations between the relatively pristine environment of the East coast and developed environment of the West and South coast ranging from 0.02 to 0.36% dw and 57.7 ng g-1 dw to 19,300 ng g-1 dw, respectively. Among diagnostic ratios of PAHs, the ratios of Ant/(Ant+Phe) and LMW/HMW drew the clearest distinctions between the East coast versus the West and South coast sediments indicating the predominance of petrogenic sources in the former versus pyrogenic sources in the latter. PAHs significantly correlated with BC and total organic carbon (TOC) in the sediments (p < 0.05) having similar correlation coefficients. BC accounted for 6.06 to 30.6% of TOC in sediments.

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.

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.

Isotope constraints of the strong influence of biomass burning to climate-forcing Black Carbon aerosols over Southeast Asia.

Black Carbon (BC) deteriorates air quality and contributes to climate warming, yet its regionally- and seasonally-varying emission sources are poorly constrained. Here we employ natural abundance radiocarbon (14C) measurements of BC intercepted at a northern Malaysia regional receptor site, Bachok, to quantify the relative biomass vs. fossil source contributions of atmospheric BC, in a first year-round study for SE Asia (December 2015-December 2016). The annual average 14C signature suggests as large contributions from biomass burning as from fossil fuel combustion. This is similar to findings from analogous measurements at S Asian receptors sites (~50% biomass burning), while E Asia sites are dominated by fossil emission (~20% biomass burning). The 14C-based source fingerprinting of BC in the dry spring season in SE Asia signals an even more elevated biomass burning contribution (~70% or even higher), presumably from forest, shrub and agricultural fires. This is consistent with this period showing also elevated ratio of organic carbon to BC (up from ~5 to 30) and estimates of BC emissions from satellite fire data. Hence, the present study emphasizes the importance of mitigating dry season vegetation fires in SE Asia.

Levels and enantiomeric signatures of organochlorine pesticides in Chinese forest soils: Implications for sources and environmental behavior.

We investigated the levels and distributions of organochlorine pesticides (OCPs) in 159 background soil samples collected from 30 forested mountain sites across China. The sum of DDT was the most abundant OCP, with the concentrations of 0.197-207 ng/g and 0.033-122 ng/g in the O-horizon and A-horizon, respectively. High concentrations of OCPs usually occur near agricultural regions or high consumption areas. The spatial distribution was mainly influenced by the emission sources and soil total organic contents (TOC). The chiral compounds were generally nonracemic in the soils and showed preferential degradation of (-) o,p'- dichlorodiphenyltrichloroethane, (+) trans-chlordane, and (-) cis-chlordane in both the O- and A-horizons. The enantiomeric fraction (EF) distributions of chiral OCPs displayed no differences across the forest sites in the O-horizon or the A-horizon. Comparing the deviation of EFs from racemic (DEVrac = absolute value of 0.500 - EF) with environmental parameters, we found that DEVrac of cis-chlordane demonstrated a strong positive correlation with TOC (p < 0.05) and the C/N ratio (p < 0.01). This relationship suggests that these factors could affect the microbial activity and significantly impact the extent of enantioselective degradation of chiral compounds in the soils. Fresh and historical applications of DDT and historical chlordane and endosulfan uses may be prominent sources of OCP accumulation in Chinese forest soils.