[Characteristics of Soil NO Emissions in the Yangtze River Delta Region for Year 2018].

Soil NO emissions represent an important source of atmospheric nitric oxide (NO) and play an important role in atmospheric chemistry. Based on the latest BDSNP algorithm, this study estimated the soil NO emissions over the Yangtze River Delta region for the year 2018 and further analyzed the associated temporal and spatial variations and uncertainties. The results showed that the annual soil NO emissions in 2018 over the YRD region was 213.6 kt, accounting for 7.3% of the total anthropogenic NOx emissions. Areas with high emissions were mainly concentrated in northern Anhui Province and most parts of Jiangsu Province. In terms of monthly variations, soil NO emissions peaked in June, accounting for 19.9% of the annual emissions and 19.7% of anthropogenic NOx emissions in June. In terms of daily variations, soil NO emissions peaked around 16:00 and accounted for 5.5% of daily emissions. Soil NO emissions came from three components:soil background, nitrogen fertilizer application, and nitrogen deposition. Nitrogen fertilizer application was the main source of soil NO emissions, accounting for up to 77.8%. With the in-depth reduction in NOx emissions from motor vehicles and industries, the importance of soil NO emissions will become increasingly prominent.

Short-term effects of air pollutants on hospital admissions for acute bronchitis in children: a multi-city time-series study in Southwest China.

BACKGROUND: Few studies have investigated the effects of air pollutants on children with acute bronchitis. This study aimed to explore the acute effects of four air pollutants [fine particulate matter (PM2.5), inhalable particulate matter (PM10), sulfur dioxide (SO2), and nitrogen dioxide (NO2)] on the daily number of children admitted to the hospital for acute bronchitis in Sichuan Province, China. METHODS: The 49,975 records of hospitalized children with acute bronchitis from medical institutions in nine cities/prefectures, Sichuan Province, China, as well as the simultaneous meteorological data and air pollution data from 183 monitoring sites, were collected from 1 January 2017 to 31 December 2018. A generalized additive model was adopted to analyze the exposure-response and lag effects of hospitalizations of children with acute bronchitis to air pollutants. Stratified analyses were conducted based on sex, age, and season. RESULTS: The single-pollutant model showed that a 10 µg/m3 increase at lag07 of PM2.5, PM10, SO2, and NO2 corresponded to an increase of 1.23% [95% confidence interval (CI) 0.21-2.26%], 1.33% (95% CI 0.62-2.05%), 23.52% (95% CI 11.52-36.81%), and 12.47% (95% CI 8.46-16.64%) in daily hospitalizations for children with acute bronchitis, respectively. Children aged 0-2 were more prone to PM2.5 (P < 0.05). Interestingly, the effects were stronger in the warm season than in transition seasons and the cool season for PM2.5 and PM10 (P < 0.05). CONCLUSION: The higher daily average concentrations of four pollutants in Sichuan Province can result in an increased number of children hospitalized for acute bronchitis.

Early life exposure to air pollution and cell-mediated immune responses in preschoolers.

BACKGROUND: Exposure to air pollution has been linked with altered immune function in adults, but little is known about its effects on early life. This study aimed to investigate the effects of exposure to air pollution during prenatal and postnatal windows on cell-mediated immune function in preschoolers. METHODS: Pre-school aged children (2.9 ± 0.5 y old, n = 391) were recruited from a mother-child cohort study in Wuhan, China. We used a spatial-temporal land use regression (LUR) model to estimate exposures of particulate matter with aerodynamic diameters ≤2.5 µm (PM2.5) and ≤10 µm (PM10), and nitrogen dioxide (NO2) during the specific trimesters of pregnancy and the first two postnatal years. We measured peripheral blood T lymphocyte subsets and plasma cytokines as indicators of cellular immune function. We used multiple informant models to examine the associations of prenatal and postnatal exposures to air pollution with cell-mediated immune function. RESULTS: Prenatal exposures to PM2.5, PM10, and NO2 during early pregnancy were negatively associated with %CD3+ and %CD3+CD8+ cells, and during late pregnancy were positively associated with %CD3+ cells. Postnatal exposures to these air pollutants during 1-y or 2-y childhood were positively associated with IL-4, IL-5, IL-6, and TNF-α. We also observed that the associations of prenatal or postnatal air pollution exposures with cellular immune responses varied by child's sex. CONCLUSIONS: Our results suggest that exposure to air pollution during different critical windows of early life may differentially alter cellular immune responses, and these effects appear to be sex-specific.

[Tree seedling distribution, regeneration mechanism and response to climate change in alpine treeline ecotone]. / é«˜å±±æž—çº¿ç”Ÿæ€äº¤é”™åŒºæœ¨æœ¬æ¤ç‰©å¹¼è‹—åˆ†å¸ƒç‰¹å¾ã€æ›´æ–°æœºåˆ¶åŠå ¶å¯¹æ°”å€™å˜åŒ–çš„å“åº”.

Tree seedlings are one of the important components in alpine treeline ecotone, whose regeneration is crucial to treeline migration in response to climate change. We analyzed the spatial distribution, regeneration of tree seedlings and their responses to climate change in treeline ecotone in recent decades. The spatial distribution of tree seedlings in treeline ecotone is dominated by diffuse and clustered forms, with different indicative significance for spatial dynamics of treeline. At global scale, the altitude distribution limits of tree seedlings are usually related to the length and average temperature of growing season, along with the species characteristics. However, precipita-tion plays an important role at regional scale. The initial stage of seedling recruitment is restricted by seed source, which determines seed distribution and germination to a great extent. Microenvironment facilitates seedling regeneration by providing shelter for establishment and improving their survival rate. The regeneration process is more relevant to multiple biotic, abiotic factors and their interactions. With global warming, rising temperature in treeline ecotone and more precipitation are more suitable for seedling regeneration of treeline species. The expansion of seedlings to higher elevations could be considered as the portent of timberline upwards migration. Due to species-specific adaption strategy, however, some trees only increase seedling density and timberline location is constant. In the future, it is necessary to take precise dating techniques, such as tree-ring and 14C dating, and conduct long-term in-situ monitoring and indoor simulation experiments. To provide scientific basis for mountain ecosystem restoration and conservation, we should strengthen the studies on spatial patterns and regeneration mechanism of seedlings in treeline ecotone at multiple spatio-temporal scales, the adaptation strategies of tree seedlings in different types of treeline ecotone and treeline dynamics prediction.

Thyroid function, phthalate exposure and semen quality: Exploring associations and mediation effects in reproductive-aged men.

BACKGROUND: A normal thyroid physiology is crucial for the maintenance of male reproductive health. Changes in thyroid hormones may represent an intermediate biological mechanism linking phthalate exposure and potential adverse health effects on male reproduction. OBJECTIVE: To investigate the mediating role of thyroid function on the association between phthalate exposure and semen quality. METHOD: Serum thyroid hormones, semen quality and repeated measures of urinary phthalate metabolites were determined among 509 reproductive-aged men in Wuhan, China. Cross-sectional associations between urinary phthalate metabolites, serum thyroid hormones and semen quality were explored using multivariable linear regressions. A mediation analysis was conducted to explore the role of thyroid function on the association of phthalate exposure with semen quality. RESULTS: Significant dose-dependent relationships were found across quartiles of monoethyl phthalate (MEP) with decreasing serum free thyroxine (FT4), which, in turn, was negatively associated with percentage of normal morphology (p for trend = 0.04). Also, we found that the proportions of di-(2-ethylhexyl)-phthalate metabolites excreted as mono-(2-ethylhexyl) phthalate (%MEHP) were negatively associated with serum thyroid-stimulating hormone (TSH) (all p for trends <0.05), which, in turn, was positively associated with progressive and total sperm motility (p for trends = 0.04 and 0.03, respectively). The mediation analysis indicated that higher urinary MEP was significantly associated with a decreasing percentage of normal morphology after controlling for thyroid hormones, and 17% of the association was mediated by serum FT4. CONCLUSIONS: Higher urinary MEP and %MEHP were associated with decreasing serum thyroid hormones, which in turn were associated with altered semen quality. Mediation analysis indicated that serum FT4 was a possible mediator of the association between urinary MEP and proportion of normal sperm morphology.