The Science of the total environment
-
Sci. Total Environ. · Aug 2019
Sand burial helps regulate timing of seed germination of a dominant herb in an inland dune ecosystem with a semiarid temperate climate.
Sand burial plays important role in the life history of species in sandy areas of arid and semi-arid temperate regions, by affecting seed germination, seedling growth and survival and plant community. However, few studies have focused on the effects of sand burial on the dynamics of seed dormancy in such areas. In this study, seed germination characteristics of Allium tenuissimum, a dominant perennial herb in the dune ecosystem in Ordos Plateau in northern China, was investigated. ⋯ The peak of nondormancy for seeds buried in the field was in the summer, which corresponds to the period of highest annual precipitation. Sand burial helped mediate seeds dormancy dynamics of A. tenuissimum via seasonal dormancy cycling. Our finding contributes to a better understanding of how timing of seedling establishment is controlled in a semiarid dune ecosystem in temperate climate.
-
Sci. Total Environ. · Jun 2019
Inactivation of bacterial and fungal spores by UV irradiation and gaseous iodine treatment applied to air handling filters.
Exposure to viable bacterial and fungal spores re-aerosolized from air handling filters may create a major health risk. Assessing and controlling this exposure have been of interest to the bio-defense and indoor air quality communities. Methods are being developed for inactivating stress-resistant viable microorganisms collected on ventilation filters. ⋯ Overall, the combined effect of UV irradiation and gaseous iodine on viable bacterial and fungal spores collected on flat filters was found to be potent. The benefit of either simultaneous or sequential treatment was much lower for Btk spores embedded inside the deep-bed (non-flattened) HEPA filter, but for A. fumigatus the inactivation on flattened and non-flattened HEPA filters was comparable. For both species, applying UV first and gaseous iodine second produced significantly higher inactivation than when applying them simultaneously or in an opposite sequence.
-
Sci. Total Environ. · Jun 2019
Gully erosion susceptibility assessment and management of hazard-prone areas in India using different machine learning algorithms.
Gully erosion is one of the most effective drivers of sediment removal and runoff from highland areas to valley floors and stable channels, where continued off-site effects of water erosion occur. Gully initiation and development is a natural process that greatly impacts natural resources, agricultural activities, and environmental quality as it promotes land and water degradation, ecosystem disruption, and intensification of hazards. In this research, an attempt is made to produce gully erosion susceptibility maps for the management of hazard-prone areas in the Pathro River Basin of India using four well-known machine learning models, namely, multivariate additive regression splines (MARS), flexible discriminant analysis (FDA), random forest (RF), and support vector machine (SVM). ⋯ The AUC results indicated that the random forest model had the highest prediction accuracy, followed by the MARS, SVM, and FDA models. However, it could be concluded that all the machine learning models performed well according to their prediction accuracy. The produced GESMs can be very useful for land managers and policy makers as they can be used to initiate remedial measures and erosion hazard mitigation in prioritized areas.
-
Sci. Total Environ. · Jun 2019
Long-term exposure to traffic-related air pollution and systemic lupus erythematosus in Taiwan: A cohort study.
Systemic lupus erythematosus (SLE) is a multi-systemic chronic autoimmune disease, the etiology of SLE is still unclear. Only a few studies evaluated the associations between air pollution and SLE. We conducted a population-based cohort study in Taiwan to examine the associations of air pollution with SLE. ⋯ Additionally, we observed negative associations with ozone (O3) and sulfur dioxide (SO2). According to the exposure-response relationships, exposure to NO2 between 28 and 38 ppb, exposure to CO above 0.6 ppm, and exposure to PM2.5 between 18 and 46 μg/m3 were positively associated with SLE. The results suggested that long-term exposure to traffic-related gaseous air pollutants (NO2 and CO) less than current National Ambient Air Quality Standards and PM2.5 are significantly associated with the risk of SLE.
-
Sci. Total Environ. · May 2019
Comparative StudyBiomonitoring of children exposure to urban pollution and environmental tobacco smoke with hair analysis - A pilot study on children living in Paris and Yeu Island, France.
The impact of pollution on children's health has been increasingly pointed out in numerous studies which emphasized their increased vulnerability compared to adults. This pilot study investigated the relevance of hair analysis for the assessment of children exposure to pollution and to environmental tobacco smoke (ETS). The methodology based on GC-MS/MS and LC-MS/MS, is the first one to investigate simultaneously parent PAH (n = 15), PAH metabolites (n = 56), nicotine and cotinine in a biological matrix. ⋯ Eight of these biomarkers presented a significantly higher concentration in children from Paris than from Yeu Island. The results suggest association between PAH exposure and estimated time of exposure to vehicle exhaust as well as higher exposure to both PAH and ETS in the youngest children. Although these findings need to be confirmed on wider populations, the results obtained in this pilot study strongly support the relevance of hair analysis for the biomonitoring of children exposure to urban pollution and ETS.