Optimal solid waste collection routes identified by the ant colony system algorithm.

In the present paper, the Ant Colony System (ACS) algorithm is used for the identification of optimal routes in the case of municipal solid waste (MSW) collection. The proposed MSW management system is based on a geo-referenced spatial database supported by a geographic information system (GIS). The GIS takes into account all the required parameters for solid waste collection. These parameters include static and dynamic data, such as the positions of waste bins, the road network and the related traffic, as well as the population density in the area under study. In addition, waste collection schedules, truck capacities and their characteristics are also taken into consideration. Spatio-temporal statistical analysis is used to estimate inter-relations between dynamic factors, like network traffic changes in residential and commercial areas. The user, in the proposed system, is able to define or modify all of the required dynamic factors for the creation of alternative initial scenarios. The objective of the system is to identify the most cost-effective scenario for waste collection, to estimate its running cost and to simulate its application. Finally, the results of the ACS algorithm are compared with the empirical method currently used by the Municipality of Athens.     

Magnetic signature,geochemistry, and oral bioaccessibility of “technogenic” metals in contaminated industrial soils from Sindos Industrial Area,Northern Greece

The objective of this study was to assess the contamination level of potentially harmful elements (PHEs) in industrial soils and how this relates to environmental magnetism. Moreover, emphasis was given to the determination of the potential mobile fractions of typically “technogenic” metals. Therefore, magnetic and geochemical parameters were determined in topsoils (0–20 cm) collected around a chemical industry in Sindos Industrial Area, Thessaloniki, Greece. Soil samples were presented significantly enriched in “technogenic” metals such Cd, Pb, and Zn, while cases of severe soil contamination were observed in sampling sites north-west of the industrial unit. Contents of Cd, Cr, Cu, Ni, Pb, Mo, Sb, Sn, and Zn in soils and pollution load index (PLI) were highly correlated with mass specific magnetic susceptibility (χ _lf). Similarly, enrichment factor (EF) and geoaccumulation index (I _geo) for “technogenic” Pb and Zn exhibited high positive correlation factors with χ _lf. Principal component analysis (PCA) classified PHEs along with the magnetic variable (χ _lf) into a common group indicating anthropogenic influence. The water extractable concentrations were substantially low, while the descending order of UBM (Unified BARGE Method) extractable concentrations in the gastric phase was Zn > Pb > As > Cd, yet Cd showed the highest bioaccessibility (almost 95%).

     

Evaluation of genotoxic variations in plant model systems in a case of metal stressors

This study was designed to assess the effects of long term, high metal exposition (cadmium, lead, copper, nickel and zinc) on DNA damage in four plant model systems [Taraxacum officinale (Asteraceae), Matricaria recutita L. (Asteraceae), Robinia pseudoacacia L. (Fabaceae), and Urtica dioica (Urticaceae)]. DNA stability was investigated by a Random Amplified Polymorphic DNA (RAPD) technique. Agarose-gel electrophoresis revealed total of 37 bands with different molecular weights ranging from 1250 to 5000 bp. It generated distinctive polymorphism value of 72.97% (27 bands) total in four plant species investigated. The dendrogram constructed using NTSYSpc programme showed that there is grouping in separate clusters of the same plant model collected from two different areas (metal-exposed and control samples). The study concluded that the long term metal-exposing periods had genotoxic stress on macromolecules of plant model systems investigated and biomarkers used should be augmented for reliable estimates of genotoxicity after exposure of plants to metal stressors.     

Oxidative stress in Cyprinus carpio to analyze microcystin impact in eutrophic shallow lakes: a preliminary study

Microcystins (MCYSTs) are toxins produced by cyanobacteria in aquatic environment and are of high potential risk to aquatic organisms. The physiological responses and pathobiological developments that they elicit in fish have been extensively studied, mainly through acute toxicity experiments. This study was designed to examine the seasonal fluctuation of biochemical markers of oxidative stress in different tissues of a natural population of Cyprinus carpio inhabiting a shallow Mediterranean lake, along with the respective MCYSTs concentrations in blood and tissues at environmentally relevant MCYSTs values. MCYSTs content was assessed in liver, kidney, intestine, brain and muscle along with the MCYSTs in lake water and scum applying ELISA technique. Catalase activity, GSH/GSSH relative concentrations and lipid peroxidation were used as biochemical markers. Our results suggest that common carp of Lake Pamvotis exposed to naturally fluctuating concentrations of MCYST in water and scum contained stably high MCYST concentrations in all tissues that might pose a threat to public health. Liver and kidney were the primary target organs. Tissue concentrations did not correlate with the response of any of the elements of the antioxidant defence system. Hepatic catalase, GSH content and TBARS in all tissues tested followed the fluctuations of major limnological parameters, i.e. water temperature and oxygen concentration, chlorophyll-a, MCYST in water and scum, suggesting that they should be cautiously used to monitor exposure to MCYSTS in natural freshwater ecosystems.     

Determining the ventilation and aerosol deposition rates from routine indoor-air measurements

Measurement of air exchange rate provides critical information in energy and indoor-air quality studies. Continuous measurement of ventilation rates is a rather costly exercise and requires specific instrumentation. In this work, an alternative methodology is proposed and tested, where the air exchange rate is calculated by utilizing indoor and outdoor routine measurements of a common pollutant such as SO₂, whereas the uncertainties induced in the calculations are analytically determined. The application of this methodology is demonstrated, for three residential microenvironments in Athens, Greece, and the results are also compared against ventilation rates calculated from differential pressure measurements. The calculated time resolved ventilation rates were applied to the mass balance equation to estimate the particle loss rate which was found to agree with literature values at an average of 0.50 h^?1. The proposed method was further evaluated by applying a mass balance numerical model for the calculation of the indoor aerosol number concentrations, using the previously calculated ventilation rate, the outdoor measured number concentrations and the particle loss rates as input values. The model results for the indoors’ concentrations were found to be compared well with the experimentally measured values.     

Explanation of fluctuations in water use time series

This paper presents techniques for studying the influence of the climatic and other variables for the explanation of the water use with an example of time series in Gainesville, Florida. A statistical methodology is described for separating the different time scale components in time series of water use, namely, long term component, seasonal component, and short term component. We analyze each component separately and we prove that the temperature, precipitation, soil temperature, and relative humidity time series are the main climatic factors for the explanation of the long term, seasonal and short term component of the water use time series. Part of the residuals derived from the linear regression of the long term component of the water use can be explained by the unemployment rate. We also show that with the decomposition of the water use time series the explanation of the water use has been improved approximately two times. The explanation of the long term component of water use by the long term regional weather parameters can enable us to the long term regional prediction of the water resources availabilities. This methodology can be applied for studying the water use time series in other locations, as well.     

Prenatal diagnosis of two rare de novo structural aberrations of the Y chromosome: cytogenetic and molecular analysis

Two rare de novo structural aberrations of the Y chromosome were detected during routine prenatal diagnosis: a satellited non-fluorescent Y chromosome (Yqs), the first de novo Yqs to be reported in a fetus, and a terminal deletion of the Y chromosome long arm del(Y)(q11). In both cases detailed cytogenetic and molecular analyses were undertaken. In the case of the Yqs it was demonstrated by fluorescence in situ hybridization (FISH) that the satellites were derived from chromosome 15. In the case of the del(Yq), it was shown with molecular analysis by polymerase chain reaction (PCR) amplification of sequence-tagged sites (STS-PCR) that the deleted portion of the long arm of chromosome Y included the azoospermia factor loci, AZFb and AZFc. The clinical significance of these findings is discussed. Copyright © 2001 John Wiley & Sons, Ltd.