Comparison of supercritical fluid extraction and Soxhlet extraction for the determination of PCBs in seaweed samples

The efficiency of supercritical fluid extraction for the determination of 12 polychlorinated biphenyls from algae samples is compared to Soxhlet extraction. Analytical detection limits for the individual congeners ranged from 0.62 microgl(-1) to 19 microgl(-1). Recovery was tested for both methods using standard addition procedure. At maximum spike level of concentration, the mean recoveries were not significantly different (P>0.05) of all PCBs studied, with the exception of PCBs 28, 52, 77 and 169. Method precision for Soxhlet extraction (< or =3.9%) was slightly better than for SFE (< or =9.2%). Although both methods yield comparable results, SFE offers the advantage of detecting all PCBs studied at lower concentrations, reducing extraction time, and reducing the amount of solvents needed. The optimized methods were applied to the analysis of three real seaweed samples, except for PCB101 the concentrations of all PCBs were low or below the detection limits. The levels of PCB101 found in sample 1 were 6.6+/-0.54 ng g(-1) d.w., in sample 2 the levels were 8.2+/-0.86 ng g(-1) d.w. and in sample 3 they were 7.7+/-0.08 ng g(-1) d.w.     

On possibilities to estimate local concentration variations with CFD-LES in real urban environments

Environmental Fluid Mechanics - Applied studies with Large Eddy Simulation (LES) of hazardous gas dispersion around buildings in cities have become increasingly feasible due to rapid advancements...     

Recovery of Soil Water,Groundwater, and Streamwater From Acidification at the Swedish Integrated Monitoring Catchments

Recovery from anthropogenic acidification in streams and lakes is well documented across the northern hemisphere. In this study, we use 1996–2009 data from the four Swedish Integrated Monitoring catchments to evaluate how the declining sulfur deposition has affected sulfate, pH, acid neutralizing capacity, ionic strength, aluminum, and dissolved organic carbon in soil water, groundwater and runoff. Differences in recovery rates between catchments, between recharge and discharge areas and between soil water and groundwater are assessed. At the IM sites, atmospheric deposition is the main human impact. The chemical trends were weakly correlated to the sulfur deposition decline. Other factors, such as marine influence and catchment features, seem to be as important. Except for pH and DOC, soil water and groundwater showed similar trends. Discharge areas acted as buffers, dampening the trends in streamwater. Further monitoring and modeling of these hydraulically active sites should be encouraged.     

Uptake,transformation, and elimination kinetics of paralytic shellfish toxins in white seabream (<Emphasis Type="Italic">Diplodus sargus</Emphasis>)

Marine toxins generated by harmful algal blooms can be transferred through the marine food web and ultimately cause massive deaths of piscivorous predators. However, very few studies have explored the processes of accumulation and biotransformation of paralytic shellfish toxins (PSTs) within fishes. White seabream (Diplodus sargus) were orally challenged with contaminated cockles (Cerastoderma edule) containing N-sulfocarbamoyl and decarbamoyl toxins and non-contaminated cockles afterwards. Specific PSTs that occurred in low abundance in cockles (B1 7.6% and dcSTX 1.6% molar fraction) were the only toxins detected in fish viscera possibly resulting from selective elimination and transformation of the various PSTs. Concentration of toxins progressively increased in fish viscera throughout the uptake period. Toxins were then rapidly depurated (B1 0.905 day⁻¹, dcSTX 0.467 day⁻¹) when diet was changed to non-toxic cockles. Results indicate conversion of a precursor toxin into B1 which in turn might be converted into dcSTX at a lower extent. Low accumulation efficiency of 1.7 and 5.0% was calculated to B1 and dcSTX, respectively. This study contributes to a better understanding of dynamics of PSTs in fish and the fate of these compounds in the marine food web.     

Long-Term Monitoring of Scots Pine Litter Decomposition Rates Throughout Sweden Indicates Formation of a More Recalcitrant Litter in the South

Decomposition studies were carried out at sites throughout Sweden, including the four Integrated Monitoring sites. Scots pine needle litterbag weight loss measurements over 3 or 5 years were determined at 26 sites and repeated up to 27 times, depending on the site. Humus layer respiration rates were determined for 20 sites in 1987–1989 and repeated in 2007–2008. Partial Least Squares (PLS) regression was used to elucidate the relative importance of climatic and soil factors. Annual needle weight losses decreased only slowly (20–10%) over 3–5 years for all northern (>60°N) sites but decreased sharply from 30 to 10% in the third year in southern (<60°N) sites. Respiration rates of southern sites were less (40% on average) than those of northern sites. Humus layer N was positively correlated to needle weight loss during the first and the second years, but negatively correlated in the third year and to respiration rates. The results indicated that litter formed in southern Sweden became more recalcitrant in later stages of decomposition compared to litter produced in northern Sweden.     

Estimation of the annual production and composition of C&D Debris in Galicia (Spain)

One of the key aspects that must be taken into consideration within the framework of Sustainable Construction is the management of Construction and Demolition (C&D) Debris. As for other types of waste, specific handling procedures are required to manage C&D Debris; these include reduction, reuse, recycling, and if all other possibilities fail, recovery or disposal. For public planning strategies aimed at the management of C&D Debris to be effective, it is first necessary to have specific knowledge of the type of waste materials generated in a particular region. After verifying that the methods available to determine the production and composition of C&D Debris are limited, this paper presents a procedure to ascertain the production and composition of C&D Debris, in any region. The procedure utilizes data on the surface areas of newly constructed buildings, renovations and demolitions, which are estimated from available data for recent years, as well as information on the quantity of debris generated per surface area in any type of construction site, which is obtained from recently executed constructions or from the ground plans of older buildings. The method proposed here has been applied to Galicia, one of Spain’s autonomous communities, for which the quantity and composition of C&D Debris have been estimated for the horizon year 2011.     

Ecotoxicological evaluation of fungicides used in viticulture in non-target organisms

Environmental Science and Pollution Research - The effect of fungicides, commonly used in vine cultures, on the health of terrestrial and aquatic ecosystems has been poorly studied. The objective...