Availability of geogenic heavy metals in soils of Thiva town (central Greece)

Potentially toxic metals in the urban chemical environment impose risks to both ecosystem and human health. Here, we evaluate the labile pools and availabilities of non-anthropogenic Ni, Cr, Co and Mn in soil samples from Thiva town (central Greece) and investigate their associations with common soil properties and geochemical data obtained by the aqua regia and single selective dissolutions. Experimental work included the initial application of the sequential extraction protocol proposed by the European Community Bureau of Reference and chemical extractions with ethylenediamine tetraacetic acid solution and a modified physiologically based extraction test with the aim to obtain the operationally defined fractions of plant availability and human bioaccessibility, respectively. The leachate results demonstrated that despite the significant contribution of residual metal species especially for Ni and Cr, the studied serpentine soils provide chemically labile pools for all the considered elements. Nickel was found to be the most available metal with the order being Ni?>?Cr?～?Co?～?Mn for plant uptake and Ni?>?Cr?>?Co?～?Mn for human bioaccessibility. The aqua regia extractable concentrations are not predictors of elemental availabilities except for Ni bioaccessible data interpreting however only a moderate percentage of the total variance. The incorporation of basic soil properties (mostly total organic carbon), geochemical data for the major elements Ca, Mg and Fe and ammonium oxalate extractable Cr significantly improved the estimations for individual elements entailing the strong influence of the chemistry and mineralogy of soil materials to the release of focus metals from the soil matrix. This study provides for the first time bioaccessible data for serpentine-derived soils that are more realistic for evaluating potential adverse effects on the human health.     

Numerical Study of the Indoor Environmental Conditions of a Large Athletic Hall Using the CFD Code PHOENICS

This study investigates, experimentally and numerically, the environmental conditions prevailing in a large mechanically ventilated athletic hall, with the aid of the computational fluid dynamics code PHOENICS. The indoor space of the building was simulated in the PHOENICS environment and the model results were validated against experimental data collected during a 10-day campaign in the hall. The measurements included airflow characteristics and pollutants concentrations at different locations of the indoor space, as well as surface temperatures of the indoor materials. Having obtained good agreement between experimental and numerical results, different scenarios were applied in the model to investigate the environmental conditions prevailing in the hall under different ventilation and occupational conditions. These regard air-conditioning, heating, and cooling modes, as well as empty and full hall during an athletic event. The airflow, temperature, and CO₂ concentration fields were studied and results revealed dynamic behavior of the fields, significantly altering with the different considered cases. The airflow patterns were characterized by distinct vortices of various sizes, originating from the ceiling air inlet fans of the heating–ventilating–air conditioning system, while temperature and pollution stratification were evident, indicating ineffective performance of the ventilation system.     

利用数字图像分析土壤表面裂隙的方向分布

利用二维数字图像方法研究了在土壤干燥过程中表面裂隙方向分布的演化状况。结果表明，随着干燥过程的持续，裂隙的长度、宽度、面积和分数维均趋于增加，但裂隙的方向分布则逐渐趋向均匀。