Seasonal and spatial variations of magnetic susceptibility and potentially toxic elements (PTEs) in road dusts of Thessaloniki city, Greece: A one-year monitoring period.

A one-year sampling campaign of road dusts was carried out at 10 distinct sites in the broader area of the city of Thessaloniki, Greece and concentrations of heavy metals (HMs) along with magnetic susceptibility were evaluated. The concentrations of HMs in road dusts were higher than their local background values, while magnetic parameters indicated a significant anthropogenic load. Principal component analysis (PCA) identified non-exhaust vehicular emissions, oil/fuel combustion and industrial activities as major sources of heavy metals accounted for approximately 73% of the total variance. A significant seasonal variability for Cr, Cu, Mn, and χlf was observed with constantly higher values during summer. Moreover, variations among urban and industrial sites were more pronounced for Cr, Cu, Zn, and χlf, while they displayed insignificant variations across all urban sites. On the contrary, concentration peaks in the urban cluster were observed for Cd, Mn, and Ni coinciding with the port area. Based on multiple pollution indices, a severe polluted area was revealed, while potential ecological risk index (RI) indicated a high potential ecological risk with Cd being regarded as the pollutant of high concern. The health risk assessment model indicated ingestion as the major exposure pathway. For both adults and children, Cr and Pb had the highest risk values, mainly recorded in the urban cluster underscoring the need of potential measures to reduce road dust in urban environments.

Pesticide residues in fruit samples: comparison of different QuEChERS methods using liquid chromatography-tandem mass spectrometry.

Acetate- and citrate-buffered quick, easy, cheap, effective, rugged, safe (QuEChERS) pretreatment methods were evaluated for the determination of various pesticides in peaches, grapes, apples, bananas, pears, and strawberries from various regions of Greece, using LC-MS/MS. The purposes of this study were (i) to evaluate which type of QuEChERS method was the most appropriate and effective for each matrix; (ii) to apply the selected QuEChERS method for each matrix, in order to detect and quantify pesticide residues in various fruit samples using UPLC-MS/MS; (iii) to examine the concentration distribution of pesticide classes among fruit originating from various areas; and (iv) to assess pesticide concentration distribution between peel and flesh of fruit in order to evaluate the penetration of pesticide residues in the fruit flesh. Acetate-buffered QuEChERS was found to be the most suitable technique for most of the fruit matrices. According to the recovery values at two different concentration levels, peaches should preferably be treated by the citrate-buffered type, whereas grapes, bananas, apples, pears, and strawberries are best treated by the acetate-buffered version, although the differences in efficiency were small. The addition of graphitized carbon black significantly decreases the recovery of specific pesticides in all matrices except for strawberries. The majority of values do not exceed the official maximum residue levels set by the European Commission. Organophosphates proved to be the most commonly detected category along with triazines-triazoles-conazoles group and by carbamates. Apples and pears seem to be the most contaminated fruit matrices among those tested. Distribution of pesticide classes shows variations between different regions, suggesting different pesticide application practices. In the case of peaches and pears, there is an equal distribution of detected pesticides between peel and flesh, indicating penetration of contaminants into the fruit flesh.

Occurrence and distribution of selected heavy metals in the surface sediments of Thermaikos Gulf, N. Greece. Assessment using pollution indicators.

Forty sediment samples and fifteen water samples were collected from the Gulf of Thermaikos and the Bay of Thessaloniki in order to determine the concentration of Zn, Cu, Pb and Cr and measure various seawater parameters. The level of pollution attributed to heavy metals was evaluated using several pollution indicators in order to determine anthropogenically derived sediment contamination. Enrichment Factors, Contamination Factors, Modified Contamination Degree, and Geoaccumulation Indexes for the sediments were used to assess and visualize using GIS. Association with adverse effects to aquatic organisms was determined, using the classification of the sediments according to the Sediment Quality Guidelines (SQGs). The highest metal levels were concentrated along the shoreline of the Bay of Thessaloniki, reflecting long-term exposure to anthropogenic activities. Enrichment Factors reveal the anthropogenic sources for chromium and lead. This is supported by separate Contamination Factors, the mean Contamination Degree, and the Geoaccumulation Index. The majority of the sediment samples can be occasionally and frequently associated to toxic biological effects, according to the effect-range classification for Zn, Cu and Pb. Based on the analysis of the overlying seawater columns it appears that under the present physicochemical conditions, dissolution of the accumulated metals from the sediments is unlikely. Although the total metal content in the sediments has decreased with time, the long-term effect of the industrial and urban activities in the area is still reflected in sediments from the gulf.

Heterogeneous photocatalytic degradation of prometryn in aqueous solutions under UV-Vis irradiation.

In this study, the heterogeneous photocatalytic degradation of prometryn using TiO(2) as photocatalyst was investigated. The main objectives of the study were: (I) to evaluate the kinetics of the pesticide disappearance, (II) to compare the photocatalytic efficiency of two different types of TiO(2), (III) to examine the influence of various parameters such as initial concentration of pesticide or catalyst and presence of oxidants (H(2)O(2) and K(2)S(2)O(8)), (IV) to evaluate the degree of mineralization and (V) to assess the detoxification efficiency of the studied processes. The experiments were carried out in a 500 ml pyrex UV reactor equipped with a 125 W high-pressure mercury lamp surrounded by a pyrex filter blocking wavelengths below 290 nm. Prometryn concentration was determined using HPLC. It was found that the degradation of the pesticide follows the first order kinetics according to the Langmuir-Hinshelwood model. Parameters like the type and concentration of the catalyst affect the degradation rate. A synergistic effect was observed when an oxidant was added in the TiO(2) suspensions increasing the reaction rate of photodegradation. In order to examine the extent of pesticide mineralization, DOC measurements were carried out. After 6h of illumination, mineralization was achieved up to almost 70%. The toxicity of the treated solution was evaluated using the Microtox test based on the luminescent bacteria Vibrio fisheri, in order to compare the acute toxicity of prometryn and its photoproducts. The detoxification efficiency was found to be dependent on the studied system and it did not follow the rate of pesticide disappearance.

Outcome of the distal ureteric stump after (hemi)nephrectomy and subtotal ureterectomy for reflux or obstruction.

OBJECTIVE: To assess the outcome of the distal ureteric stump (DUS) after (hemi)nephrectomy with subtotal ureterectomy. PATIENTS AND METHODS: The records of 89 patients (median age 2.7 years, range 0.25-12) who underwent nephrectomy (24) or heminephrectomy (65) with subtotal ureterectomy between 1982 and 1996 were reviewed retrospectively for symptoms caused by the DUS. The mean follow-up was 9.8 years. Nephrectomy was undertaken for a poorly functioning dysplastic (in nine), scarred (in 10) or hydronephrotic (in five) kidney, and heminephrectomy for a poorly functioning upper moiety associated with ectopic ureterocele (in 26) or stenotic hydroureter (in 15), or for a poorly functioning lower moiety associated with reflux (in 24). There were 38 refluxing and 51 non-refluxing ureteric stumps. Two additional patients primarily operated elsewhere were referred with DUS symptoms. RESULTS: Only one patient had a symptomatic DUS, with recurrent haematuria and bacteriuria. The two patients referred from elsewhere presented with febrile UTIs. The first had been left with a long refluxing stump opening ectopically into the urethra, and the second with a long stump which was converted from nonrefluxing to a refluxing stump when he developed dysfunctional voiding. Surgical excision of the distal stump was curative in each case. CONCLUSIONS: The risk of a symptomatic DUS in patients who undergo subtotal ureterectomy in conjunction with (hemi)nephrectomy is very low, with no difference between refluxing and nonrefluxing stumps. Long ureteric stumps and dysfunctional voiding may cause symptoms. Because of the low morbidity associated with a short ureteric stump, we recommend subtotal ureterectomy in children who undergo (hemi)nephrectomy for reflux, vesico-ureteric obstruction or ectopic ureterocele associated with a poorly functioning kidney or kidney moiety.