Suchergebnisse

Tea is one of the world's most popular beverages. Economic and social interest in tea is clear from the fact that about 18-20 billion tea cups are being consumed daily in the world. Consequently, chemical components in tea leaves have received great interest because they are related to health and disease. Various reports have discussed the potential health implications of some chemical factors such as heavy metals in tea, particularly since tea bush is known to accumulate trace metals. Metallic constituents of tea leaves depend on the type of tea and geological origin. In the present study four tea samples (two black and two green) and four herbal tea samples (two Mentha piperita and two Matricaria chammomilla) were collected from the local market in Belgrade, Serbia, in May 2008. The sample preparation has been performed using wet and dry digestion procedures. The metal content (Cu, Zn, Mn, Cd, Ni and Pb) in the digested samples has been analyzed by using flame atomic absorption spectrometry. The comparison of wet and dry digestion has shown significant differences in results, indicating that dry digestion is more appropriate method. The levels of the examined metals obtained by dry digestion in this study compared well with those reported for tea samples from some other parts of the world. Among the investigated metals, the most abundant nutritive metal, Mn, has been the highest with 26.0 to 199.3 mg/kg, while fortunately toxic heavy metal, Cd, has been below the detection limit (0.1 mg/kg). The concentrations of lead and nickel have been in the range 5.1-13.7 and 1.4- -4.4, respectively. The content of lead in two samples (Mentha piperita) has been higher than the maximum permissible concentration of 10 mg/kg specified by the national legislation. ; U ovom radu su ispitivane koncentracije bakra, cinka, mangana, nikla, kadmijuma i olova u uzorcima čajeva (crni, zeleni, nana, kamilica) uzetih iz lokalnih prodavnica u Beogradu u maju 2008. godine. Priprema uzoraka vršena je mokrom i suvom digestijom. Koncentracije odabranih metala u rastvorima posle digestije određivane su plamenom atomskom apsorpionom spektrofotometrijom. U svim uzorcima posle suve digestije, najviša je bila koncentracija mangana (26,0 do 199,3 mg/kg), dok kadmijum nije detektovan ni u jednom uzorku. Sadržaj bakra je varirao od 7,7 do 14,1 mg/kg, cinka od 6,9 do 26,9 mg/kg, olova od 5,1 do 13,7 mg/kg, a nikla od 1,4 do 4,4 mg/kg. U oba ispitivana uzorka čaja od lista nane koncentracija olova je bila iznad 10 mg/kg, koliko je dozvoljeno zakonskom regulativom Republike Srbije.

Intensive industrial development has led to the increase of pollutants in the air, water and land. In order to gain a clear insight into the sources of emissions, many countries have implemented registers of pollutants in their legislation, which represent the basis for responsible policies in the field of environmental protection, as well as the base for the implementation of a cleaner production and encouraging the introduction of cleaner technologies. Strategic and legal framework and analysis of the current situation represent the base for development of the Local register environmental pollution sources at the territory of Belgrade city. Integral part of the Register is pollutant types and emitted amounts. Predicting these emissions is of a great importance for decision makers when finding adequate solutions for the control. Models based on artificial neural networks have been applied intensively these years in the field of environmental protection and sustainable development. In present work, developed ANN emission models have been applied for the modeling of SOx, NOx PM10, and GHGs emission in the air at annual level for Belgrade, for the period 2008-2010. ; Do povećanja emisije zagađujućih materija u vazduh, vodu i zemljište došlo je zbog intenzivnog industrijskog razvoja. Kako bi se stekao jasan uvid u izvore emisije, mnoge zemlje su, u svoju zakonsku regulativu, implementirale registre zagađivača, koji predstavljaju osnovu za odgovornu politiku u oblasti zaštite životne sredine, kao i osnovu za implementaciju čistije proizvodnje i stimulisanje uvođenja čistijih tehnologija. Strateški i pravni okvir i sagledavanje postojećeg stanja predstavlja osnovu za izradu Lokalnog registra izvora zagađivanja životne sredine na teritoriji Grada Beograda, čiji je sastavni deo baza podataka o zagađivačima, odnosno vrstama i emitovanim količinama. Predviđanje ovih emisija je od velikog značaja, kako bi donosioci odluka na vreme mogli da pronađu adekvatna rešenja. Modeli zasnovani na neuronskim mrežama se poslednjih godina intenzivno primenjuju za simulacije u oblasti zaštite životne sredine i održivog razvoja. U okviru ovog rada izvršeno je modelovanje emisije u vazduh SOx, NOx, PM10 i GHG, na godišnjem nivou za Grad Beograd, za period 2008-2010. godina. Dobijeni rezultati pokazuju da je emisija sumpornih oksida za sve tri posmatrane godine bila mnogo viša od emisija NOx (oko 7 puta) i PM10 (oko 3 puta). Na osnovu dobijenih rezultata za GHG može se zaključiti da se GHG emisija povećala u 2010. godini za 17 % u odnosu na 2008. godinu.