Concentrations and Availability Indicators of Soil Heavy Metals; the Case of Children’s Playgrounds in the City of Athens (Greece)

This study reports on the concentrations, distribution, and availability of heavy metals in the children’s playground soils of Athens. Playgrounds were chosen because they are open city areas; they show relatively even spatial distribution within the district of Athens and are used by a great number of young children and their escorts on a regular basis. Samples were collected from 70 playground surface soils, representing more than 70% of the city’s playgrounds. Cu, Zn, Pb, Cr, Ni, Co, Mn, and Fe were extracted by aqua regia and by diethylene triamine pentaacetic acid (DTPA) to estimate total and available metal forms, respectively. Their mean total concentrations were 43, 174, 110, 80, 82, 22, 312, and 17?×?10³?mg kg^?1, respectively. The DTPA-extracted fraction showed much lower values, with means of 2.5, 7.8, 5.8, 1.5, 1.3, 0.4, 8.4, and 2.0 mg kg^?1 respectively, which, however, should be carefully monitored since they relate directly to the bioavailable fraction of heavy metals. Though mean values of metal concentrations are not particularly high, the calculated enrichment factors indicate site-specific cases of high enrichment with heavy metals. Considering that the bioavailable fraction of a metal is possibly a more appropriate indicator for the recent soil pollution history, availability ratios were calculated and their distribution was visualized over the entire city profile using the appropriate GIS software. It was shown that recent metal pollution events appear to have affected mostly playground sites in the southern and eastern part of the municipality.     

Hen egg yolk lipid fractions with antiatherogenic properties

Three different types of hen egg yolk, cage‐free, organic and daily fresh, were tested for their antiatherogenic properties. Total lipids (TL) of all hen egg yolk samples were extracted by the method of Bligh and Dyer and further separated into total polar lipids (TPL) and total neutral lipids (TNL) by counter current distribution chromatography. TPL and TNL were further separated by preparative thin‐layer chromatography (TLC). TL, TPL, TNL and the obtained polar and neutral lipid fractions after TLC separation were tested to determine whether they induce platelet activation or inhibit platelet activating factor (PAF)‐induced platelet activation. All three hen egg yolk TL samples possessed strong inhibitory activity against PAF‐induced platelet activation that was mainly attributed to TPL, especially to PL fraction 4. Cage‐free hen egg yolk exhibited the most potent anti‐PAF activity in all lipid classes (TL, TPL and TNL). Thus hen egg yolk contains PAF inhibitors that reinforce their nutritional value in terms of protection against cardiovascular diseases, since PAF is a crucial inflammatory phospholipid mediator that is implicated in the mechanism of atherogenesis.     

Effect of nitrogen in combination with elevated temperatures on insects,microbes and organoleptic characteristics of stored currants

In the present study, the effect of nitrogen, applied as a controlled atmosphere treatment on the microbial and entomological loads, as well as on the organoleptic characteristics of stored dried currants (Corinthian raisins, Vitis vinifera L. var. Apyrena), was investigated. Trials were conducted under “real world” conditions, in the nitrogen chambers of a commercial facility, in which nitrogen was introduced by using an incorporated nitrogen generator. Prior to the initiation of the trial, chambers were filled with pallets carrying dried black currants. Subsequently, currants were artificially infected with all life stages of Tribolium confusum, eggs and larvae of Ephestia elutella and adults of Oryzaephilus surinamensis. Currants were exposed for 3 days in nitrogen (O₂ concentration <1 %) at two temperature levels, 25 and 38–43 °C. After treatment, insect mortality was recorded and currant samples were collected and forwarded for microbial analysis and determination of their organoleptic characteristics. When nitrogen was applied at 25 °C, high insect mortality levels were noted; however, in most cases there were a number of insects that survived the nitrogen treatment. In contrast, complete control was achieved at 38–43 °C for all insect species and life stages tested, with the exception of T. confusum larvae. Nitrogen application at 25 °C had no effect on total microbial and yeast and mould counts, while both were reduced at 38–43 °C. Sensory attributes of Corinthian currants remained acceptable after nitrogen fumigation, although taste, odour, aroma and overall acceptance were affected by the treatments. Total phenolic as well as 5-hydroxymethylfurfural content increased after nitrogen application at 38–43 °C, while the lower temperature applied had no effect. The results of the present study suggest that nitrogen-based controlled atmosphere at elevated temperature could be a valuable tool for ensuring clean, pest-free, hygienic standards in dried Corinthian currants.