(1) Background: Radon concentrations in the environment are generally very low. However, radon concentrations can be high indoors and can cause some serious health issues. The main source of indoor ...radon (homes, buildings and other residential objects) can be soil under the house, while other sources can be construction materials, groundwater and natural gas. Radon accumulates mainly in the lower levels of the buildings (especially low-ventilated underground levels and basements). (2) Methods: in this paper, we have measured the indoor radon concentrations at 15 locations in various objects (basements and ground floor/1st floor rooms) in the area of northern Croatia. (3) Results: the results show a higher concentration of radon in the basement area in comparison to values measured in the ground floor and first-floor rooms. The arithmetic mean (AM) and geometric mean (GM) of basement rooms were 70.9 ± 38.8 Bq/m3 and 61.2 ± 2.2 Bq/m3 compared to ground floor and first-floor rooms 42.5 ± 30.8 Bq/m3 and 32.8 ± 2.9 Bq/m3, respectively. (4) Conclusions: results obtained (AM and GM values) are within the maximal allowed values (300 Bq/m3) according to the Euroatom Directive. However, there are periods when maximum radon concentration exceeds 300 Bq/m3. Indoor radon concentrations vary with the occupancy of the rooms and it is evident that the ventilation has significant effect on the reduction of concentration.
Gospodarenje otpadnom plastikom Budiša, Mirko; Ptiček Siročić, Anita
Kemija u industriji; časopis kemičara i tehnologa Jugoslavije,
09/2022, Letnik:
71, Številka:
9-10
Journal Article
Recenzirano
Odprti dostop
U zadnjih pedesetak godina zabilježen je značajan rast količina plastičnog otpada koji nekontroliranim odbacivanjem postaje sve veći problem za okoliš i sa značajnim posljedicama na živuće ...ekosustave. Plastika je važan i sveprisutan materijal u gospodarstvu i svakodnevnom životu i godišnje u zemljama Europske unije nastaje blizu 26 milijuna tona plastičnog otpada. Oko 30% tog otpada se reciklira, znatan dio se energetski oporabljuje, a dio se još uvijek odlaže i na odlagališta otpada. Recikliranjem plastičnog otpada čuvaju se prirodne sirovine kao što su nafta i zemni plin koje se upotrebljavaju za proizvodnju plastičnih materijala te se smanjuju emisije u okoliš i potrošnja energije. Planom za resursno učinkovitu Europu, plastični otpad prepoznat je kao važna sirovina za proizvodnju novih proizvoda i jedna je od ključnih sirovina u prelasku na kružno gospodarstvo. U ovom je radu dan prikaz općih mogućnosti recikliranja tj. oporabe plastičnog otpada. Na temelju indikativnih rezultata ispitivanja sastava odvojeno prikupljenog plastičnog otpada u Zagrebu dana je procjena mogućnosti njegove reciklaže. U Republici Hrvatskoj plastični otpad velik je problem budući da se adekvatno ne sortira. Zbog toga je značajno financijsko opterećenje komunalnim društvima koja njime gospodare u sklopu javne usluge prikupljanja komunalnog otpada.
During the summer months from 2014 to 2016, water was sampled at two lakes in Zagreb, Jarun and Bundek, with the aim of determining the number of colonies of microbiological indicators of ...Escherichiae coli and intestinal enterococci. We have investigated the dependence of microbiological water quality indicators on sampling points. Also, we were interested in determining the influence of the season of the year. This research identified that regular monitoring of microbiological indicators is necessary, especially at locations used by people for recreation or other purposes, in order to prevent possible infections.
The impact of the contaminants in post used PET bottles on the decomposition of polymer itself after recycling process was analyzed. For that reason sorption experiments of harmful substances to PET ...bottles were performed. In order to monitor the presence of contaminants in recycled PET and evolution of thermal decomposition products of samples: virgin PET, contaminated PET flakes (PET K) and recycled PET (PET RM) were studied. The thermal degradation products of PET were achieved by pyrolysis using Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS), temperature-programmed evolved gas analysis-mass spectrometry (EGA-MS) and thermogravimetric analysis (TGA). Reactive pyrolysis with tetramethyl ammonium hydroxide (TMAH) was also performed to gather additional information about degradation products in studied samples. The pyrolysis products analysis of the studied PET samples indicate some changes in decomposition mechanism of PET samples that pass through contamination process due to some diversity in their chemical and structural composition.
Chemical composition of bottled water on Croatian market Ptiček Siročić, Anita; Dogančić, Dragana; Bosilj, Mateja
e-zbornik. Elektronički zbornik radova Građevinskog fakulteta,
6/2023, Letnik:
13, Številka:
25
Journal Article
Recenzirano
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The Ordinance on natural mineral, natural spring and table waters regulates the market of bottled water. The Directive on the quality of water intended for human consumption sets water quality ...standards and three categories of parameters (microbiological, chemical and indicator). Microbiological parameters show the degree of water pollution by microorganisms, while chemical parameters show the degree of water pollution by different chemical substances. Natural spring and natural mineral water have a certain chemical composition in which the concentrations of individual elements have the prescribed maximum allowable amount. If the concentrations of individual elements exceed the maximum allowed amount, they can have a harmful effect on the human body. All categories of bottled water (table, spring and mineral) can be carbonated and non-carbonated, depending on the carbon dioxide (CO2) content. Due to extracting and bottling of drinking water, in order to improve its quality, it is necessary continuously conduct analyses that prove the safety of drinking water.
The studied samples were prepared from polyethylene (PE) polymer which was coated with modified polycaprolactone (PCL) film in order to obtain bilayer films. Thin PCL film was modified with ...casein/aluminum oxide compound to enhance vapor permeability as well as mechanical and thermal properties of PE/PCL films. Casein/aluminum oxide modifiers were used in order to achieve some functional properties of polymer film that can be used in various applications, e.g., reduction of water vapor permeability (WVTR) and good mechanical and thermal properties. Significant improvement was observed in mechanical properties, especially in tensile strength as well as in water vapor values. Samples prepared with aluminum oxide particles indicated significantly lower values up to 60%, and samples that were prepared with casein and 5% Al2O3 showed the lowest WVTR value.
A low-cost and fast potentiometric surfactant sensor for cationic surfactants, based on the new ion-pair 1,3-dioctadecyl-1H-imidazol-3-ium-tetraphenylborate (DODI-TPB), is presented. The new cationic ...surfactant DODI-Br was synthesized and characterized by NMR, LC-MS, and elemental analysis, and was used for synthesis of the DODI-TPB ionophore. The DODI-TPB surfactant sensor was obtained by implementation of the ionophore in PVC. The sensor showed excellent response characteristics with near-Nernstian slopes to the cationic surfactants DMIC, CPC, CTAB, and Hyamine 1622. The highest voltage responses were obtained for DMIC and CPC (58.7 mV/decade of activity). DMIC had the lowest detection limit (0.9 × 10−6 M) and the broadest useful linear concentration range (1.8 × 10−6 to 1.0 × 10−4 M). An interference study showed remarkable stability. Potentiometric titration curves for the titration of cationic surfactants (DMIC, CPC, CTAB, and Hyamine 1622), with DDS and TPB used as titrants, showed sigmoidal curves with well-defined inflexion points and a broad signal change. The standard addition method was successfully applied with recovery rates from 98.9 to 101.2 at two concentrations. The amount of cationic surfactant found in disinfectants and antiseptics was in good agreement with the referent two-phase titration method and the surfactant sensor on the market. This new surfactant sensor represents a low-cost alternative to existing methods for cationic surfactant detection.
U ovom su radu analizirani fizikalno-kemijski pokazatelji kakvoće otpadnih voda (kemijska potrošnja kisika (KPK), biokemijska potrošnja kisika (BPK5), koncentracija suspendiranih tvari) tijekom ...ljetnih mjeseci (lipanj, srpanj i kolovoz) 2013. i 2014. godine na centralnom uređaju za pročišćavanje otpadnih voda Čakovec, koji je predviđen za drugi stupanj pročišćavanja. Ljetni mjeseci 2014. godine ne pokazuju značajnija odstupanja vrijednosti pojedinih pokazatelja, ali u odnosu na iste mjesece u 2013. godini srednje mjesečne vrijednosti znatno su niže i nalaze se unutar dopuštenih maksimalnih koncentracija. Rezultati za lipanj, srpanj i kolovoz 2013. i 2014. godine ukazuju na učinkovito pročišćavanje otpadnih voda na pročistaču.
Various combinations of matrix, filler and classical additives lead to wide possibilities of improving material specifications for mechanical, thermal and structural properties. The studied samples ...were prepared from a primary polyethylene (PE) layer coated with a thin film of polycaprolactone (PCL) and modified with magnetite, casein/magnetite and zeolite/magnetite compounds. Enhancements to mechanical properties were observed, especially tensile strength and thermal properties for bilayer PE/PCL films prepared using casein and magnetite (Fe
3
O
4
) compounds. Adding various modifiers increased the melting and crystallization enthalpy, indicating an increase in PE crystallinity and changes to thermal transitions of bilayer PE/PCL modified films.
The Plitvice Lakes National Park is in the northwestern part of the Dinaric Karst in central Croatia. An important role of the soil in the karst is to purify the waters before they reach the phreatic ...zone. The soil is also a zone of accumulation, transformation, retardation and dilution of a potential pollutant. Knowing soil mineralogical composition is an important factor in understanding fate and transport of contaminants throughout lakes system. Samples of soil, peat and stream sediment were collected in the Prošće lake catchment and partly in the assumed zone of influence, X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR) analysis of samples was performed to determine dominant mineral species in samples. XRD analysis showed predominance of lowquartz, which was found in all samples, most often as dominant phase. Dolomite was found in half of the samples, almost always as a significant phase while calcite was dominant phase in one of the samples. In most of the samples, members of the feldspars and chlorites groups, as well as muscovite, were present as minor phases. The absorption bands in the range of 2800-3000 cm-1 due to the organic matter are visible in spectra of all samples. These minerals can enter lakes system by surface waters, primarily streams and overland flow during snow thawing and rain, and also in cases of shore erosion. Terrigenic input in lakes is small but cannot be neglected due to the longlasting preservation efforts of the Prošće Lake recharge area, and the Plitvice Lakes National Park in general, terrigenous intake still does not pose a threat to water quality and tufa production. Considering the analyzed samples and characteristics of detected soil constituents, soils and sediments in the Prošće Lake catchment have the ability to retain and purify water on its way to the lakes. On the other hand, in case of the possible contamination in the recharge area of the lakes system, the pollutants can enter the system adsorbed on the soil particles. Learning more about the soils surrounding lakes gives valuable insight into their possible influence on lakes water chemistry and adds one piece of the puzzle into understanding this kind of a natural phenomenon.
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