Polycyclic aromatic hydrocarbons (PAHs) are compounds with two or more benzene rings whose hydroxylated metabolites (OH-PAHs) are excreted in urine. Human PAH exposure is therefore commonly estimated based on urinary OH-PAH concentrations. However, no study has compared PAH exposure estimates based on urinary OH-PAHs to measurements of PAH levels in blood samples. Estimates of PAH exposure based solely on urinary OH-PAHs may thus be subject to substantial error. To test this hypothesis, paired measurements of parent PAHs in serum and OH-PAHs in urine samples from 480 participants in Guangzhou, a typical developed city in southern China, were used to investigate differences in the estimates of human PAH exposure obtained by sampling different biological matrices. The median PAH concentration in serum was 4.05 ng mL⁻¹, which was lower than that of OH-PAHs in urine (8.33 ng mL⁻¹). However, serum pyrene levels were significantly higher than urinary levels of its metabolite 1-hydroxypyrene. Concentrations of parent PAHs in serum were not significantly correlated with those of their metabolites in urine with the exception of phenanthrene, which exhibited a significant negative correlation. Over 28% of the participants had carcinogenic risk values above the acceptable cancer risk level of 10⁻⁶. Overall, estimated human exposure and health risks based on urinary 1-hydroxypyrene levels were only 13.6% of those based on serum pyrene measurements, indicating that estimates based solely on urine sampling may substantially understate health risks due to PAH exposure.

Understanding the comprehensive effect on crop production and quality, soil acidification, and Cd accumulation and distribution for wheat-rice rotation under N fertilization and continuous straw return is important for proper contaminated agricultural soil management. A 2-year paddy field experiment was conducted to study the effects of above factors change in the Zhejiang province, China. Fertilization treatments included: conventional N fertilizer application (N3), 20% reduction of N application (N2), 40% reduction of N application (N1), combined with three portions of straw incorporation: all straws retention (N3), half of the straws into the fields (S2), 20% straws retention(S1). The N1 treatments significantly decreased crop yields compared to N2 and N3 treatments. Except for C2-wheat, soil pH generally decreased with increasing N fertilizer input in the order of N1>N2>N3, regardless of how many straws was amended. Moreover, we found that straw addition plus N fertilization had a intersystem impacts on Cd accumulation, distribution and availability. Although total Cd had different trends among 4 experimental seasons, when the N reduced 20% applied, the DTPA-Cd contents were lowest among 3 out of four experimental seasons, except for that of C2-wheat, where N2 treatments ranked the second lower contents. For most seasons, Cd contents in straws were higher than soils and lowest in grains, and S2N2 treatment performed an intermediate value among all treatments. Furthermore, our study demonstrated that S2 or N2 treatments or S2N2 reduced the potential risk of plant diseases and pests with lower disease index, disease cluster rate. Notably, the relative outbreak of pests was remarkably suppressed under S2 treatments, especially S2N2. Thus, these findings demonstrated that in wheat-rice rotation reducing 20% N fertilization with 50% straw returning may be a win-win practice in this region for the equilibrium between agricultural productivity, quality and low Cd polluted risk.

Plants can take up and transform brominated flame retardants (BFRs) and organophosphate flame retardants (OPFRs) from soil, water and the atmosphere, which is of considerable significance to the geochemical cycle of BFRs and OPFRs and their human exposure. However, the current understanding of the plant uptake, translocation, accumulation, and metabolism of BFRs and OPFRs in the environment remains very limited. In this review, recent studies on the accumulation and transformation of BFRs and OPFRs in plants are summarized, the main factors affecting plant accumulation from the aspects of root uptake, foliar uptake, and plant translocation are presented, and the metabolites and metabolic pathways of BFRs and OPFRs in plants are analyzed. It was found that BFRs and OPFRs can be taken up by plants through partitioning to root lipids, as well as through gaseous and particle-bound deposition to the leaves. Their microscopic distribution in roots and leaves is important for understanding their accumulation behaviors. BFRs and OPFRs can be translocated in the xylem and phloem, but the specific transport pathways and mechanisms need to be further studied. BFRs and OPFRs can undergo phase I and phase II metabolism in plants. The identification, quantification and environmental fate of their metabolites will affect the assessment of their ecological and human exposure risks. Based on the issues mentioned above, some key directions worth studying in the future are proposed.

Mercury (Hg), as a global pollutant, its contamination has been documented in environmental compartments of the Himalayan region. However, little research exists regarding to Hg accumulation in terrestrial wildlife, as well as its driving factors. In this study, surface soil and small mammals were collected in the Lebu Valley, East Himalayas of China, in order to measure the uptake of the long-distance transported Hg along an elevational gradient approximately from 2300 to 5000 m a.s.l. The soil Hg concentrations were measured and predicted mostly by vegetation type as well as soil organic matter, while the Hg in hair of small mammals (Muridae and Cricetidae) showed deeply influenced by soil Hg. Notably, combined with the field survey data, soil and hair Hg were both enhanced in low and mid-elevations, which overlapped the distribution ranges of a majority of mammals. Overall, this indicates that Hg contamination in low- and mid-elevations poses a potential threat to the top predators that consuming small mammals directly or indirectly. Furthermore, our data advances the understanding of Hg dynamics in remote, high mountain ecosystems and provides baseline data for biomonitoring for reduction of Hg emission globally.

Informal electrical and electronic waste (e-waste) handling activities constitute a potentially important source of halogenated (HFRs) and organophosphate flame retardants (OPFRs) to the environment and humans. In this review, two electronic databases (ScienceDirect and Web of Science Core Collection) were searched for papers that addressed this topic. A total of 82 relevant studies (including 72 studies selected from the two databases and 10 studies located from the references of the first 72 selected studies) were identified that reported on human external and internal exposure to HFRs and OPFRs arising as a result of informal e-waste handling activities. Compared to the general population, higher levels of external exposure (i.e., inhalation, ingestion, and dermal absorption) and internal exposure (i.e., blood serum, hair, breast milk, urine, and other human matrices) to HFRs and OPFRs were identified for e-waste recyclers and residents inhabiting e-waste dismantling and recycling zones, especially for younger adults and children. Food intake and dust ingestion were the dominant exposure pathways for the majority of brominated flame retardants (BFRs) and dechlorane plus (DP); while inhalation was identified as the most significant pathway of human exposure to OPFRs in informal e-waste sites. The majority of research to date has focused on China and thus future studies should be conducted in other regions such as Africa and South Asia. Other suggested foci of future research are: examination of exposure via dermal contact with e-waste, dietary exposure of local populations to OPFRs, confirmation of the existence of and cause(s) of the higher body burdens of females compared with males amongst populations impacted by informal e-waste handling, and characterisation of exposure of such populations to chlorinated paraffins.

Light-absorbing organic carbon (or brown carbon, BrC) has been recognized as a critical driver in regional-to-global climate change on account of its significant contribution to light absorption. BrC sources vary from primary combustion processes (burning of biomass, biofuel, and fossil fuel) to secondary formation in the atmosphere. This paper investigated the light-absorbing properties of BrC such as site-specific mass absorption cross-section (MACBᵣC), absorption Ångström exponent (AAEBᵣC), and the absorbing component of the refractive index (kBᵣC) by using light absorption measurements from a 7-wavelength aethalometer over an urban environment of Chiang Mai, Thailand in northern peninsular Southeast Asia (PSEA), from March to April 2016. The contribution of BrC to total aerosol absorption (mean ± SD) was 46 ± 9%, 29 ± 7%, 24 ± 6%, 20 ± 4%, and 15 ± 3% at 370, 470, 520, 590, and 660 nm, respectively, highlighting the significant influence of BrC absorption on the radiative imbalance over northern PSEA. Strong and significant associations between BrC light absorption and biomass-burning (BB) organic tracers highlighted the influence of primary BB emissions. The median MACBᵣC and kBᵣC values at 370 nm were 2.4 m² g⁻¹ and 0.12, respectively. The fractional contribution of solar radiation absorbed by BrC relative to BC (mean ± SD) in the 370–950 nm range was estimated to be 34 ± 7%, which can significantly influence the regional radiation budget and consequently atmospheric photochemistry. This study provides valuable information to understand BrC absorption over northern PSEA and can be used in model simulations to reassess the regional climatic impact with greater accuracy.

Finding the potential environmental obesogens is crucial to explain the prevalence of obesity and the related pathologies. Increasing evidence has showed that many chemicals with endocrine disrupting effects can disturb lipid metabolism. Whether 4-hexylphenol (4-HP), a widely-used surfactant and a potential endocrine disrupting chemical (EDC), is associated to influence adipogenesis and hepatic lipid accumulation remained to be elucidated. In this study, both the 3T3-L1 differentiation model and oleic acid (OA)-treated HepG2 cells were used to investigate the effects of 4-HP on lipid metabolism, and the underlying estrogen receptor (ER)-involved mechanism was explored using MVLN assay, molecular docking simulation and the antagonist test. The results based on lipid droplet staining and triglyceride accumulation assay showed that 4-HP treatment promoted the adipogenic differentiation of 3T3-L1 cells and increased hepatic cellular OA accumulation in exposure concentration-dependent manners. The study on the elaborated transcription networks indicated that 4-HP activated peroxisome proliferator-activated receptor γ (PPARγ) as well as the subsequent adipogenic gene program in 3T3-L1 cells. This chemical also induced the increase of OA uptake and decreases of de novo lipogenesis and fatty acid oxidation in HepG2 cells. The agonistic activity of 4-HP in triggering ER-mediated pathway was shown to correlate with its perturbation in lipid metabolism, as evidenced by the enhanced development of mature lipid-laden adipocytes and suppression of excessive hepatic lipid accumulation upon its co-treatment with ER antagonist. Altogether, these findings provide new insights into the potential health impacts of 4-HP exposure as it may relate to obesity and nonalcoholic fatty liver disease.

Enhanced release of phosphorus (P) from soils with snowmelt flooding poses a threat of eutrophication to waterbodies in cold climatic regions. Reductions in P losses with various soil amendments has been reported, however effectiveness of MgSO₄ has not been studied under snowmelt flooding. This study examined (a) the P release enhancement with flooding in relation to initial soil P status and (b) the effectiveness of MgSO₄ at two rates in reducing P release to floodwater under simulated snowmelt flooding. Intact soil monoliths were collected from eight agricultural fields from Southern Manitoba, Canada. Unamended and MgSO₄ surface-amended monoliths (2.5 and 5.0 Mg ha⁻¹) in triplicates were pre-incubated for 7 days, then flooded and incubated (4 °C) for 56 days. Pore water and floodwater samples collected at 7-day intervals were analyzed for dissolved reactive P (DRP), pH, Ca, Mg, Fe and Mn. Redox potential (Eh) was measured on each day of sampling. Representative soil samples collected from each field were analyzed for Olsen and Mehlich 3-P. Simulated snowmelt flooding enhanced the mobility of soil P with approximately 1.2–1.6 -fold increase in pore water DRP concentration from 0 to 21 days after flooding. Mehlich-3 P content showed a strong relationship with the pore water DRP concentrations suggesting its potential as a predictor of P loss risk during prolonged flooding. Surface application of MgSO₄ reduced the P release to pore water and floodwater. The 2.5 Mg ha⁻¹ rate was more effective than the higher rate with a 21–75% reduction in average pore water DRP, across soils. Soil monoliths amended with MgSO₄ maintained a higher Eh, and had greater pore water Ca and Mg concentrations, which may have reduced redox-induced P release and favored re-precipitation of P with Ca and Mg, thus decreasing DRP concentrations in pore water and floodwater.

In this study, Gymnodinium aeruginosum was exposed to polystyrene (PS) and polymethyl methacrylate (PMMA) of three particle sizes (0.1 μm, 1.0 μm and 100 μm) and two concentrations (10 mg/L and 75 mg/L) for 96 h. The density of algae cells, the endpoints that reactive oxygen species (ROS), total protein (TP), malondialdehyde (MDA), superoxide dismutase (SOD) and catalase (CAT), scanning and transmission electron microscopy (SEM and TEM) were used to explore the toxicity mechanism to the microalgae. At a concentration of 75 mg/L, the 96 h inhibition ratios (IR) with particle sizes of 0.1 μm, 1.0 μm and 100 μm on G. aeruginosum were 55.9%, 63.7% and 6.0% for PS, respectively, and 3.0%, 4.1% and ‐0.6% for PMMA, respectively. The most significant changes in ROS, TP, MDA, SOD and CAT were observed at 75 mg/L 1.0 μm of PS when treated for 96 h. When exposed to nanoplastics (NPs) and microplastics (MPs), the algae cells were damaged, and the antioxidant system was activated. Extracellular polymeric substance (EPS) could help to detoxify the algae. In general, PS was more toxic than PMMA. The toxicity of small MNPs (0.1 μm and 1.0 μm) was related to the concentrations, while large MNPs (100 μm) did not.

PM₂.₅ in Shijiazhuang was collected from October 15, 2018 to January 31, 2019, and selected toxic elements were measured. Five typical haze episodes were chosen to analyze the health risks and critical risk sources. Toxic elements during the haze episodes accounted for 0.33% of PM₂.₅ mass. Non-cancer risk of toxic elements for children was 1.8 times higher than that for adults during the haze episodes, while cancer risk for adults was 2.5 times higher than that for children; cancer and non-cancer risks were primarily attributable to As and Mn, respectively. Health risks of toxic elements increased during the growth and stable periods of haze episodes. Non-cancer and cancer risks of toxic elements during the haze stable periods were higher than other haze stages, and higher for children than for adults during the stable period. Mn was the largest contributor to non-cancer risk during different haze stages, while As was the largest contributor to cancer risk. Crustal dust, vehicle emissions, and industrial emissions were critical sources of cancer risk during the clean-air periods; while vehicle emissions, coal combustion, and crustal dust were key sources of cancer risk during the haze episodes. Cancer risks of crustal dust and vehicle emissions during the haze episodes were 2.0 and 1.7 times higher than those in the clean-air periods. Non-cancer risks from emission sources were not found during different periods. Cancer risks of biomass burning and coal combustion increased rapidly during the haze growth period, while that of coal combustion decreased sharply during the dissipation period. Vehicle emissions, crustal dust, and coal combustion were significant cancer risk sources during different haze stages, cancer risk of each source was the highest during the stable period. Southern Hebei, Northern and central Shaanxi were potential risk regions that affected the health of both adults and children in Shijiazhuang.