Pulse diffusive nitrous oxide (N₂O) emission following water application is well documented, whereas N₂O emission caused by soil water-air displacement during the watering process (termed as soil degassing) has been largely overlooked. Watering-induced N₂O emissions from ten different soils in China were quantified, and found to range from 74.4 ± 6.7 to 678.1 ± 36.6 μg N₂O m⁻² h⁻¹ in surface watered (SW) soils, and from 45.6 ± 4.4 to 358.1 ± 23.6 μg N₂O m⁻² h⁻¹ in subsurface watered (SUW) soils. These N₂O fluxes were much larger than the diffusive N₂O flux from the same soil either under dry (7.9%–9.6% water filled pore space, WFPS) or wet (85.1%–93.6% WFPS) conditions. The watering process (the water infiltration process upon irrigation/rainfall or the process of shallow groundwater uplifting) resulted in massive N₂O emissions.

In Part II of this work we present the results of the downscaled offline Weather Research and Forecasting/Community Multiscale Air Quality (WRF/CMAQ) model, included in the “Technology Driver Model” (TDM) approach to future U.S. air quality projections (2046–2050) compared to a current-year period (2001–2005), and the interplay between future emission and climate changes. By 2046–2050, there are widespread decreases in future concentrations of carbon monoxide (CO), nitrogen oxides (NOx = NO + NO2), volatile organic compounds (VOCs), ammonia (NH3), sulfur dioxide (SO2), and particulate matter with an aerodynamic diameter ≤ 2.5 μm (PM2.5) due mainly to decreasing on-road vehicle (ORV) emissions near urban centers as well as decreases in other transportation modes that include non-road engines (NRE). However, there are widespread increases in daily maximum 8-hr ozone (O3) across the U.S., which are due to enhanced greenhouse gases (GHG) including methane (CH4) and carbon dioxide (CO2) under the Intergovernmental Panel on Climate Change (IPCC) A1B scenario, and isolated areas of larger reduction in transportation emissions of NOx compared to that of VOCs over regions with VOC-limited O3 chemistry. Other notable future changes are reduced haze and improved visibility, increased primary organic to elemental carbon ratio, decreases in PM2.5 and its species, decreases and increases in dry deposition of SO2 and O3, respectively, and decreases in total nitrogen (TN) deposition. There is a tendency for transportation emission and CH4 changes to dominate the increases in O3, while climate change may either enhance or mitigate these increases in the west or east U.S., respectively. Climate change also decreases PM2.5 in the future. Other variable changes exhibit stronger susceptibility to either emission (e.g., CO, NOx, and TN deposition) or climate changes (e.g., VOC, NH3, SO2, and total sulfate deposition), which also have a strong dependence on season and specific U.S. regions.

The ubiquitous presence of microplastics (MPs) has been demonstrated in all environmental compartments in the recent years. They are detected in air, freshwater, soil, organisms and particularly in marine ecosystems. Since sediments are known to be the major sink of many organic and inorganic pollutants, the aim of this study was to develop and validate a fast and cheap methodology to assess the MP contamination in intertidal sediments from the Gulf of Biscay (Pays de la Loire region, France). Sediments were sampled at three locations (Pays de la Loire region, France) and during two seasons: October 2015 and March 2016. The analytical protocol involved MP extraction from dried sediments using milliQ water and a centrifugation technique. After a filtration step of supernatants, MPs were detected and directly identified on the membrane filters using μFTIR spectroscopy in reflection mode. For the first time, the number of replicates allowing to obtain a satisfying representativeness of the whole sampled sediment was also evaluated at 10 replicates of 25 g each. The average number of MPs in sediments was 67 (±76) MPs/kg dw (N = 60) with no significant difference between sites and seasons. Ten different compositions of MPs were defined by μFT-IR with a high proportion of polypropylene (PP) and polyethylene (PE), 38 and 24%, respectively. Among MPs, mainly fragments (84%) were observed with main size classes corresponding to [>100 μm] and [50–100 μm] but no particles > 1 mm could be found suggesting that mainly small microplastics (<1 mm) were subject to vertical transport.

The research was conducted to investigate the accumulation, distribution and availability of Cd in paddy soil and their relation to Cd in rice plants under 30-year fertilization regimes. Six treatments were involved in the study: control without fertilization (CK), chemical fertilizer (NPK), high nitrogen chemical fertilizer (HN), rice straw incorporation (ST), low and high dosage of manure fertilizer (LM and HM). Total and DTPA extractable concentration of Cd (T-Cd and DTPA-Cd) in bulk soils (20 cm topsoil), profiles (0–60 cm) and aggregates (>2, 1–2, 0.5–1, 0.25–0.5, 0.053–0.25 and < 0.053 mm) were investigated. The Cd concentration in relevant rice plant (roots, stems, leaves, husks and grains) were also analyzed. Manure fertilizers caused T-Cd accumulation in bulk soil with a significant increase of 36.2% in LM and 81.2% in HM. Similar impacts of manure fertilizers were observed in DTPA-Cd in the bulk soil. Further, the HM generated a further accumulation in deeper soil layers, presenting a remarkable increase of T-Cd (28.3%–225%) in 10–40 cm and DTPA-Cd (116%–158%) in 10–30 cm profiles. Moreover, the continuous application of manure fertilizers enhanced the availability of Cd in all aggregate size classes with an increase of 17.3%–87.8% in DTPA-Cd. Organic fertilizers (LM, HM and ST) heightened the content of Cd (38.0%–152%) in all parts of rice plant. The accumulation of Cd in rice plants was directly affected by fertilization regimes and Cd availability in the 10–20 cm soil layers and 0.25–0.5 mm aggregates. In conclusion, long-term application of manures resulted in increasing availability of Cd in aggregates and in topsoil and subsoil layers, which accordingly enhanced the accumulation of Cd in rice plants.

The purpose of this study is to verify the hypothesis that chronic obstructive pulmonary disease (COPD) model rat is more susceptible to cold stress and fine particulate matter (PM2.5) exposure than the healthy rat, and explore the related mechanism. COPD rat model, established with cigarette smoke and lipopolysaccharide intratracheal instillation, were exposed to cold stress (0 °C) and PM2.5 (0, 3.2, 12.8 mg/ml). After that, the levels of superoxide dismutase, inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF-α), monocyte chemotactic protein 1 (MCP-1) and angiotensin Ⅱ (Ang-Ⅱ) in lung were measured, as well as the expression levels of lung 8-hydroxy-2-deoxyguanosine (8-OHdG), nuclear factor kappa B (NF-κB), heme-oxygenase-1 (HO-1) and nuclear factor erythroid-2-related factor 2 (Nrf2). There were significant positive relationships between PM2.5 and lung level of iNOS, TNF-α, MCP-1 and Ang-Ⅱ, lung function and pathologic damage in COPD rats. The HO-1, NF-κB and 8-OHdG were found highly expressed in COPD rat lung, particularly at the higher PM2.5 dose of cold stress groups, while Nrf2 was found declined. Thus, COPD rats may be more susceptible to cold stress and PM2.5 exposure. Cold stress may aggravate PM2.5-induced toxic effects in the lung of COPD rats through increasing Ang-Ⅱ/NF-κB signaling pathway and suppressing Nrf2 signaling pathway.

Prenatal exposure to polychlorinated biphenyl (PCB) is suspected to interfere with fetal development including reproductive and thyroid function and birth outcomes, but published evidence are still sparse. We designed a cross-sectional study to analyze the associations between PCB levels in umbilical cord sera and hormones and birth outcomes of mothers and newborns who are residents from an island. Seven indicator-PCB (PCB-28, 52, 101, 118, 138, 153, 180), and five reproductive hormones including luteotropic hormones (LH), estradiol (E2), testosterone (T), follicle-stimulating hormones (FSH) and anti-Mullerian hormones (AMH), and three thyroid hormones including tri-iodothyronine (T3), tetra-iodothyronine (T4) and thyroid stimulating hormones (TSH) were measured in 106 cord sera specimens. Birth outcomes include birth weight, length, head circumference, and gestational age. Multiple linear regression and quartile regression were used to analyze the associations between PCB and each of the hormones and birth outcomes, adjusting for selected potential confounders. The median value of total PCB in umbilical cord sera was 2.02 μg L−1 (IQR, 1.13–4.64). Several negative associations between PCB exposure and reproductive hormones were found. Among them, the β value of PCB-101 for FSH reached −0.38 (95%CI, −0.69, −0.07; p = 0.02). Moreover, we also found some sex-specific associations i.e. PCB-28 was negatively correlated with LH and T and PCB-118 was negatively correlated with T in male newborns but not in female newborns. The associations between PCB and birth outcomes seem to differ by molecular weight of the PCB congeners i.e. the low-chlorinated PCB congeners were negatively associated with gestational age and head circumference while high-chlorinated PCB congeners were positively associated birth weight and gestational age. In this study, we found that PCB congeners with different molecular weight has different associations with hormones and birth outcomes, and future studies are recommended to investigate underlying mechanisms of these associations.

To investigate the biological pathways involved in phthalate-induced developmental effects, zebrafish embryos were exposed to different concentrations of di-(2-ethylhexyl) (DEHP) and di-butyl phthalate (DBP) for 96 h. Embryonic exposure to DEHP and DBP induced body length decrease, yolk sac abnormities, and immune responses (up-regulation of immune proteins and genes). The lipidomic results showed that at a concentration of 50 μg/L, DEHP and DBP significantly reduced the levels of fatty acids, triglycerides, diacylglycerol, and cholesterol. These effects are partly explained by biological pathway enrichment based on data from the transcriptional and proteomic profiles. Co-exposure to DBP and ER antagonist did not significantly relieve the toxic symptoms compared with exposure to DBP alone. This indicates that phthalate-induced developmental abnormities in zebrafish might not be mediated by the ER pathway. In conclusion, we identified the possible biological pathways that mediate phthalate-induced developmental effects and found that these effects may not be driven by estrogenic activation.

Electronic cigarette (e-cigarette) use has steadily increased since 2010. Indoor e-cigarette use exposes bystanders to a new source of particulate matter (PM) air pollution. Elevated short-term exposures to PM with a lower measuremented aerodynamic diameter (≤2.5 μm), PM₂.₅ and ultrafine particles (UFPs) have been linked to increased risk of adverse respiratory and cardiac events. This exposure study estimated concentrations of PM₂.₅ and UFPs from indoor e-cigarette use at 0.5 meters (m) and 1 m away from an e-cigarette user and investigated whether these indoor concentrations varied across three common e-cigarette models. One e-cigarette user tested three different e-cigarettes containing the same nicotine solution on three separate occasions and measured concentrations on PM₂.₅ and UFPs at 0.5 and 1 m in a ∼38 m³ office. Continuous measures of PM₂.₅ and UFPs were taken for 5.5 min before e-cigarette use, then the user puffed seven times for 6.5 min (exposure), and for 10 min after ceasing e-cigarette use. Following the initiation of e-cigarette use, levels of PM₂.₅ increased 160-fold at a distance of 0.5 m, and 103-fold at 1 m. The corresponding increases in UFP counts were 5.2, and 3.0-fold higher, respectively. The PM₂.₅ concentrations and UFP counts between e-cigarette models were statistically significantly different at 1 m, but not at 0.5 m. There was substantial variability between distances, e-cigarettes, and replicates. This study indicates that e-cigarette vapors influence PM₂.₅ and UFPs concentrations/counts at close proximity distances indoors; additional research is needed to characterize the composition of those particles and evaluate the impacts of other e-cigarette solutions on indoor air quality.

This research is designed to determine the level and types of pollution in the highly contaminated sediments of the international Begej canal in Timiş district, Romania and north-eastern Serbia. The cross-border canal stretch investigated is currently not navigable, but represents an important waterway between the Danube River in Serbia and the city of Timisoara. Surface sediments were monitored annually from 2008 to 2016 at 36 representative sampling locations, with a wide range of analyses, including eight heavy metals of long-term monitoring concern (Ni, Zn, Cd, Cr, Cu, Pb, As and Hg) and the 16 USEPA PAHs. The purpose of this study was to determine the diversity and impact of anthropogenic and natural sources of pollution at the pollution hot spots on the canal: at the Itebej lock (near the border with Romania) and downstream at the Klek lock.Sediment quality and ecological risk were assessed in order to determine pollutants of concern. Several multi-proxies were applied (e.g. geo-accumulation index (Igₑₒ), ecological risk index (RI) and total benzo[a]pyrene equivalent (B[a]Pₑq)). To determine and predict trends, multivariate statistical methods (factor analysis of principal component analysis (PCA/FA)) were carried out on the organic and inorganic parameters analysed.In the near-border region, acute and significant ecological impacts were observed. The heavy metals Hg, Cr, Pb, Cu and Zn, and the carcinogenic PAH dibenzo[a,h]anthracene, were historically the most frequently detected harmful substances to biota in this and the wider Pannonia region. This is the first long-term study to quantify and derivate the most frequently detected harmful substances of concern for this and similar sites in the wider region, and is additionally supported by significant national and similar environmental data from previous studies in the region.

We describe a batch-extraction with simulated digestive fluid (salivary fluid, gastric fluid and intestinal fluid) to estimate the bioaccessibility of inhaled trace metals (TMs) in particulate matter less than 10 and 2.5 μm in aerodynamic diameter (PM₁₀ and PM₂.₅). Concentrations of the assayed TMs (As, Cd, Cr, Ni, Mn, Cu, Zn, Sb, Hg and Pb) were determined in PM₁₀ and PM₂.₅ samples by inductively coupled plasma-mass spectrometry. The TMs with the largest soluble fractions for airborne PM collected from winter and summer in saliva were Mn and Sb, respectively; in seasons this became Co in gastric fluid and Cu in intestinal fluid. Clearly, bioaccessibility is strongly dependent on particle size, the component of simulated digestive fluids (e.g., pH, digestive enzymes pepsin and trypsin), and the chemical properties of metal ions. The particle size and seasonal variation affected the inhaled bioaccessible fraction of PM-bound TMs during mucociliary clearance, which transported PM from the tracheal and the bronchial region to the digestive system. This study provides direct evidence for TMs in airborne PM being bioaccessible TMs are likely to possess an enhanced digestive toxic potential due to airborne PM pollution.