Toxic and essential trace elements in human milk from Greek lactating women: association with dietary habits and other factors

The aim of this study was to determine the concentration of some essential and toxic metals in the colostrum and transitory human milk in conjunction with various factors that may influence their concentrations i.e. diet, supplementation, place of residence, smoking, as well as socioeconomic and somatometric characteristics. Zinc, iron, copper, manganese, cadmium and lead were measured by AAS in 180 colostrum samples from healthy lactating women collected on third day postpartum. A second milk sample was collected in 95 (53%) subjects 14 days later. Dietary habits were assessed by a 7-day food frequency questionnaire and various characteristics and socio-economic factors were also recorded. The mean (+/-standard deviation) values of colostrum samples were: Zn 4905 +/- 1725 microg l(-1), Fe 544 +/- 348 microg l(-1), Mn 4.79 +/- 3.23 microg l(-1), Cu 381 +/- 132 microg l(-1), Cd 0.190 +/- 0.150 microg l(-1), Pb 0.48 +/- 0.60 microg l(-1). All metals with the exception of copper were found in lower concentrations in transitory samples. Cadmium and lead weekly intakes were found to be below the Maximum Tolerable Weekly Intakes as they have been established for infants by WHO or NRC. Our results revealed: higher Pb concentration in the samples from urban areas; effect of smoking on Cu level; dietary habits seem to play a role in metal levels in human milk as the logistic regression models revealed.     

Investigation of Cr(VI) reduction in continuous-flow activated sludge systems

The aim of this research was to investigate hexavalent chromium, Cr(VI), reduction by activated sludge and to evaluate the use of continuous-flow activated sludge systems for the treatment of Cr(VI)-containing wastewater. Three series of experiments were conducted using two parallel lab-scale activated sludge systems. During the first experiment, one system was used as a control, while the other received Cr(VI) concentrations equal to 0.5, 1, 3 and 5mg l(-1). For all concentrations added, approximately 40% of the added Cr(VI) was removed during the activated sludge process. Determination of chromium species in the dissolved and particulate phase revealed that the removed Cr(VI) was sorbed by the activated sludge flocs mainly as trivalent chromium, Cr(III), while the residual chromium in the dissolved phase was mainly detected as Cr(VI). Activated sludge ability to reduce Cr(VI) was independent of the acclimatization of biomass to Cr(VI) and it was not affected by the toxic effect of Cr(VI) on autotrophic and heterotrophic microorganisms. During the second experiment, both systems were operated under two different hydraulic residence time (theta equal to 20 and 28h) and three different initial organic substrate concentration (COD equal to 300, 150 and 0mg l(-1)). Cr(VI) reduction was favored by an increase of theta, while it was limited by influent COD concentration. Finally, at the last experiment the effect of anoxic and anaerobic reactors on Cr(VI) reduction was investigated. It was observed that the use of an anoxic zone or an anaerobic-anoxic zone ahead of the aerobic reactor favored Cr(VI) reduction, increasing mean percentage Cr(VI) reduction to almost 80%.     

Effect of municipal waste water effluent upon the expression of Glutathione S-transferase isoenzymes of brine shrimp Artemia

Multiple isoenzymes of the detoxification enzyme family Glutathione S-transferase are expressed in the brine shrimp Artemia. The number of the major ones detected in crude extract by means of chromatofocusing varied between three and four, depending on the age. Two isoenzymes, one alkaline and one neutral (with corresponding isoelectric points of 8.5 and 7.2) appear to be dominant in all three developmental stages studied, (24, 48, and 72 h after hatching). Culturing Artemia for 48 h after hatching, in artificial sea water prepared by municipal wastewater effluent resulted to significant alterations of the isoenzyme profile. In comparison to organisms cultured for the same period of time in artificial sea water prepared by filtered tap water, the expression of the alkaline isoenzyme decreased by 62% while that of the neutral isoenzyme increased by 58%. Furthermore, the enzyme activity of the major isoenzyme of the acidic area increased by more than two folds. It is worth mentioning that although the specific activity of the total enzyme in the whole body homogenate was elevated, no statistically significant alteration of the Km value was observed. These findings suggest that study of the isoenzyme profile of Glutathione S-transferase may offer high sensitivity in detecting environmental pollution and needs to be further investigated.     

The fate of dissolved organic carbon (DOC) in the wastewater treatment process and its importance in the removal of wastewater contaminants

Goal, Scope and Background Dissolved organic carbon (DOC) constitutes a parameter of organic pollution for waters and wastewaters, which is not so often studied, and it is not yet regulated by directives. The term ‘DOC’ is used for the fraction of organics that pass through a 0.45 μm pores’ size membrane. The type of wastewater plays an important role in the quality of DOC and it has been shown that DOC may contain aquatic humic substances, hydrophobic bases, hydrophobic neutrals, hydrophilic acids, hydrophilic bases and hydrophilic neutrals. The quality of the DOC is expected to affect its fate in a wastewater treatment plant (WWTP), since a considerable fraction of DOC is not biodegradable, and it may be released in the aquatic environment together with the treated effluent. In the present study, the occurrence of DOC during the wastewater treatment process is investigated and its removal rates during primary, secondary and overall treatment are being estimated. Furthermore, a correlation is being attempted between DOC and the concentrations of selected Persistent Organic Pollutants (POPs) and Heavy Metals (HMs) in the dissolved phase of wastewaters, to examine whether there are common sources for these pollution parameters in WWTPs. Also, DOC is being correlated with the partition coefficients of the above-mentioned pollutants in wastewater, in order to examine the effect of ‘solubility enhancement’ in WWTPs and to evaluate the result of this phenomenon in the efficiency of a WWTP to remove organic pollutants. Methods For the purposes of this study, 24-h composite wastewater samples were collected from the influent (raw wastewater, RW), the effluent of primary sedimentation tank (primary sedimentation effluent, PSE) and the effluent of secondary sedimentation tank (secondary sedimentation effluent, SSE). Samples were analyzed for the presence of 26 POPs (7 PCBs and 19 organochlorine pesticides), 8 HMs and DOC. Results and Discussion Mean concentrations of DOC in RW and PSE were at similar levels (∼ 70 mg l⁻¹), suggesting that primary treatment has a minor effect on the DOC content of wastewater. DOC concentrations in SSE were significantly lower (∼ 19 mg l⁻¹) as a result of the degradation of organic compounds in the biological reactor. Calculated removals of DOC were 0.8% in the primary treatment, 63% in the secondary treatment, and 69% in the overall treatment, exhibiting large differences from other organic pollution parameters, such as BOD and COD. The overall DOC removal was found to be independent from the DOC concentration in raw wastewater. Poor correlation was also observed between the DOC content and the concentrations of wastewater contaminants, such as persistent organic pollutants (POPs) and heavy metals (HMs), probably suggesting that their occurrence in WWTPs is due to different sources. A good negative linear relationship was revealed between DOC concentrations and the logarithms of the distribution coefficients (K _d) of various POPs and HMs between the solid and the liquid phases of wastewater. This relationship suggests that DOC facilitates hydrophobic pollutants to remain in the dissolved phase thus causing lower removal percentages during the treatment process. Conclusion DOC was measured at three stages of a municipal WWTP that receives mainly domestic wastewater and urban runoff. DOC concentrations in untreated and primarily treated wastewater were almost equal, and only after the secondary sedimentation there was a decrease. Concentrations and removal rates of DOC were in the same levels as in other WWTPs that receive municipal wastewater. The origin of DOC was found to be different to the one of POPs and of HMs, as no correlation was observed between the concentrations of DOC and the concentrations of these pollutants. On the contrary, DOC was found to have significant negative correlation with the K _d of all pollutants examined, suggesting that it plays an important role in the partitioning of those pollutants between the dissolved and the sorbed phase of wastewaters. This effect of DOC on partitioning can affect the ability of WWTPs to remove toxic pollutants, and that way it facilitates the discharge of those chemicals in the aquatic ecosystems together with the treated effluent. Recommendation By the results of this work it is shown that the presence of DOC in wastewaters can significantly affect the partition of hazardous pollutants between the dissolved and the sorbed phase. It is therefore of importance that this parameter is controlled more in wastewaters, since it can cause a decrease in the efficiency of WWTPs to remove quantitatively persistent pollutants.     

Occurrence and assessment of polycyclic aromatic hydrocarbons in soils from vegetable fields of the Pearl River Delta, South China

Surface soil (0-20 cm) samples from nine representative vegetable fields located in Guangzhou, Shenzhen, Zengcheng and Huadu within the Pearl River Delta, South China were collected and analyzed for 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) using gas chromatography coupled to mass spectrometry (GC-MS). Total concentrations of 16 PAHs (Sigma(PAHs)) ranged from 160 to 3700 microg kg(-1). Large variations were observed also between concentrations of individual PAHs from different vegetable fields and within the site as well. Acenapthylene, benzo[b]fluoranthene, fluoranthene, benzo[a]pyrene and benzo[k]fluoranthene were consistently the most prevalent individual PAHs. The values of PAH isomer ratios [anthracene/(anthracene+phenanthrene) and fluoranthene/(fluoranthene+pyrene)] indicate that combustion processes are the major sources of PAHs. Concentrations of PAHs were poorly correlated with organic carbon concentrations of soils, suggesting different sources and also indicating that the PAH pollution of this area is recent. The same outcome is confirmed by the predominance of PAHs with fewer rings (相似文献   

Case studies on summertime measurements of O3, NO2, and SO2 with a DOAS system in an urban semi-industrial region in Athens, Greece

The objective of this study is to analyze the concentrations of SO₂, NO₂, and O₃ measured by a Differential Optical Absorption Spectroscopy (DOAS) system that was operating at the campus of Technological Education Institute of Piraeus during 2008 and 2009 warm periods (July to September) in relation to the prevailing meteorological conditions. The DOAS system was operating in a particularly polluted area of the West part of Attica basin on a continuous basis, measuring the concentration levels of the main pollutants (O₃, NO₂, and SO₂) as well as aromatic hydrocarbon substances (benzene, toluene, and xylene). According to the analysis, the SO₂ concentration levels at this measuring site are rather high and this may be attributed to the characteristics of this measuring site. Proximity of roadways and local circulation are just some of the factors that can affect the concentration levels of monitoring of pollutant concentrations such as NO₂ and surface ozone. The results provide evidence for the occurrence of an atmospheric phenomenon that produces higher ozone concentrations during weekends despite lower concentrations of ozone precursors. This phenomenon is known as the weekend effect.     

Chemical composition and mass closure of ambient coarse particles at traffic and urban-background sites in Thessaloniki,Greece

Concentrations and chemical composition of the coarse particle fraction (PM_c) were investigated at two urban sites in the city of Thessaloniki, Greece, through concurrent sampling of PM₁₀ and PM_2.5 during the warm and the cold months of the year. PM_c levels at the urban-traffic site (UT) were among the highest found in literature worldwide exhibiting higher values in the cold period. PM_c levels at the urban-background site (UB) were significantly lower exhibiting a reverse seasonal trend. Concentration levels of minerals and most trace metals were also higher at the UT site suggesting a stronger impact from traffic-related sources (road dust resuspension, brake and tire abrasion, road wear). According to the chemical mass closure obtained, minerals (oxides of Si, Al, Ca, Mg, Fe, Ti, and K) dominated the PM_c profile, regardless of the site and the period, with organic matter and secondary inorganic aerosols (mainly nitrate) also contributing considerably to the PM_c mass, particularly in the warm period. The influence of wind speed to dilution and/or resuspension of coarse particles was investigated. The source of origin of coarse particles was also investigated using surface wind data and atmospheric back-trajectory modeling. Finally, the contribution of resuspension to PM_c levels was estimated for air quality management perspectives.     

Forecasting daily pollen concentrations using data-driven modeling methods in Thessaloniki,Greece

Airborne pollen have been associated with allergic symptoms in sensitized individuals, having a direct impact on the overall quality of life of a considerable fraction of the population. Therefore, forecasting elevated airborne pollen concentrations and communicating this piece of information to the public are key issues in prophylaxis and safeguarding the quality of life of the overall population. In this study, we adopt a data-oriented approach in order to develop operational forecasting models (1–7 days ahead) of daily average airborne pollen concentrations of the highly allergenic taxa: Poaceae, Oleaceae and Urticaceae. The models are developed using a representative dataset consisting of pollen and meteorological time-series recorded during the years 1987–2002, in the city of Thessaloniki, Greece. The input variables (features) of the models have been optimized by making use of genetic algorithms, whereas we evaluate the performance of three algorithms: i) multi-Layer Perceptron, ii) support vector regression and iii) regression trees originating from distinct domains of Computational Intelligence (CI), and compare the resulting models with traditional multiple linear regression models. Results show the superiority of CI methods, especially when forecasting several days ahead, compared to traditional multiple linear regression models. Furthermore, the CI models complement each other, resulting to a combined model that performs better than each one separately. The overall performance ranges, in terms of the index of agreement, from 0.85 to 0.93 clearly suggesting the potential operational use of the models. The latter ones can be utilized in provision of personalized and on-time information services, which can improve quality of life of sensitized citizens.     

Arsenic and Other Metal Contamination of Groundwaters in the Industrial Area of Thessaloniki, Northern Greece

In groundwater, used for drinking water supply in the greater industrial area of Thessaloniki, in Northern Greece, concentrations of total arsenic exceeded the WHO provisional guideline value and the EU maximum contaminant level (MCL) of 10 μg/L. The concentration of total arsenic was in the range between 4–130 μg/L, whereas the median value was 36 μg/L and the average concentration 46 μg/L. Nine out of the eleven wells contained total arsenic at concentration higher than 10 μg/L and it should be stressed that 6 of them contain arsenic at concentrations between 10 (new MCL) and 50 μg/L (previous MCL). The examined groundwaters were found to contain elevated concentrations of manganese and phosphate. Arsenic had a positive correlation with the pH, indicating the possible effect of pH on arsenic mobilisation. These findings emerge the problem of contamination from arsenic, since, according to the EU directive 98/83, all drinking water sources within the European Union should have achieved compliance with the new limits by 12/2003, implying that the situation requires urgent remedial action.     

Investigation of powered 2-wheeler accident involvement in urban arterials by considering real-time traffic and weather data

Objective: Understanding the various factors that affect accident risk is of particular concern to decision makers and researchers. The incorporation of real-time traffic and weather data constitutes a fruitful approach when analyzing accident risk. However, the vast majority of relevant research has no specific focus on vulnerable road users such as powered 2-wheelers (PTWs). Moreover, studies using data from urban roads and arterials are scarce. This study aims to add to the current knowledge by considering real-time traffic and weather data from 2 major urban arterials in the city of Athens, Greece, in order to estimate the effect of traffic, weather, and other characteristics on PTW accident involvement.

Methods: Because of the high number of candidate variables, a random forest model was applied to reveal the most important variables. Then, the potentially significant variables were used as input to a Bayesian logistic regression model in order to reveal the magnitude of their effect on PTW accident involvement.

Results: The results of the analysis suggest that PTWs are more likely to be involved in multivehicle accidents than in single-vehicle accidents. It was also indicated that increased traffic flow and variations in speed have a significant influence on PTW accident involvement. On the other hand, weather characteristics were found to have no effect.

Conclusions: The findings of this study can contribute to the understanding of accident mechanisms of PTWs and reduce PTW accident risk in urban arterials.