Observations on solid phase micro-extraction for MTBE analysis

In a recent study of aqueous phase methyl tertiary butyl ether (MTBE) adsorption onto hydrophobic molecular sieves, the solid phase micro-extraction gas chromatography analytical technique was used to measure MTBE concentrations in water. The method was especially beneficial in measuring MTBE concentrations in the microg/l range, but anomalies were observed that investigators should be aware of before employing this technique. Specifically, it was observed that the calibration of the extraction fiber with known MTBE concentrations was non-linear over all concentration ranges. The technique was not suited to higher concentrations, and dilutions were necessary to increase the working range of the technique. Lastly, the fiber was observed to extract increasingly less MTBE from known standard solutions over time, requiring repeated calibrations to obtain reliable concentrations of unknown samples.     

Biosorption characteristics of copper (II), chromium (III), nickel (II), and lead (II) from aqueous solutions by Chara sp. and Cladophora sp.

The aim of this research was to expose individual removals of copper, chromium, nickel, and lead from aqueous solutions via biosorption using nonliving algae species, Chara sp. and Cladophora sp. Optimum pH values for biosorption of copper (II), chromium (III), nickel (II), and lead (II) from aqueous solutions were determined to be 6, 7, 7, and 3 for Cladophora sp. and 5, 3, 5, and 4 for Chara sp. respectively. Maximum adsorption capacities of Chara sp. [10.54 for chromium (III) and 61.72 for lead (II)] and Cladophora sp. [6.59 for chromium (III) and 16.75 and 23.25 for lead (II)] for chromium (III) and lead (II) are similar. On the other hand, copper (II) and nickel (II) biosorption capacity of Cladophora sp. [14.28 for copper (II) and 16.75 for nickel (II)] is greater than Chara sp. [6.506 for copper (II) and 11.76 for nickel (II)]. Significantly high correlation coefficients indicated for the Langmuir adsorption isotherm models can be used to describe the equilibrium behavior of copper, chromium, nickel, and lead adsorption onto Cladophora sp. and Chara sp.     

Trace metal concentrations and their distribution in the lobster Panulirus inflatus (Bouvier, 1895) from the Mexican Pacific coast

The concentration and distribution of Fe, Mn, Ni, Cu, Co, Cd, Cr and Zn among the tissues of female and male lobster Panulirus inflatus from the Pacific coast of México were determined. Distinct inter-tissue and intersize differences in metal concentrations were observed. In general, highest Zn concentrations were found in viscera while highest Cu levels occurred in the gill and gonadal material. The highest Mn, Ni, Cr and Co concentrations were observed in exoskeleton and highest in eggs and gills. Cadmium was undetectable (<0.05 microg g(-1)) in most tissues, only muscle and viscera contained low but detectable amounts. A positive relationship between size and metal concentration was observed only for Zn contained in the muscle of females and males, for Zn contained in the gonad of females, for Mn contained in the gonad of males and for Cu associated with muscle of males. These results are discussed with regard to trace metal concentrations found in temperate and tropical regions.     

Trace element accumulation in the moss Hypnum cupressiforme Hedw. and the trees Quercus ilex L. and Pinus halepensis Mill. in Catalonia

We studied trace element accumulation in the moss Hypnum cupressiforme and the widely distributed Mediterranean trees Quercus ilex and Pinus halepensis located at increasing distances from the Barcelona Metropolitan Area. Hypnum cupressiforme, Quercus ilex and, to a somewhat lesser extent, Pinus halepensis, have proved to be adequate as possible accumulative monitoring species in relation to trace elements pollution. No significant effects of crown orientation were found. One-year old leaves generally accumulated more trace elements than current-year leaves. All the studied trace elements showed greatest concentrations in the Barcelona Metropolitan Area, with lead, cadmium and arsenic concentrations being especially high. In general, trace element concentrations in biomass were similar or higher than the values reported from other Mediterranean urban areas of Europe. The top soil-layer concentrations were also higher in the Barcelona Metropolitan Area indicating the existence of mechanisms of atmospheric deposition and/or concentration in the soil. The lower values of Pb of airborne origin relative to other elements such as Cd, Cu, Zn and Sb suggest that traffic exhausts are not the only important focus of pollutants in this area. The results of biomass concentrations and of enrichment factor of biomasses respect to bedrock and soils show that atmospheric inputs account for the higher trace element concentrations in the Barcelona Metropolitan Area.     

Seasonal patterns of non-terpenoid C6-C10 VOC emission from seven Mediterranean woody species

The seasonal pattern of non-terpenoid C6-C10 VOC emission by seven Mediterranean woody species (Bupleurum fruticosum, Cistus albidus, Pinus halepensis, Arbutus unedo, Erica arborea, Quercus coccifera, and Q. ilex) was studied under field conditions. Branch chamber samples were sorbed on carbotrap and analyzed by thermal desorption in combination with GC-MS. These non-terpenoid C6-C10 VOC emissions were large, almost of similar magnitude to those of terpenes. Overall, maximum values were recorded in spring and summer (up to 12 microg g(-1) DM h(-1) in Q. ilex) and minimum values in autumn and winter (up to 5 microg g(-1) DM h(-1) in Q. ilex). These C6-C10 VOC emissions represented 2.82% of the photosynthetic C fixation in summer and 0.22% in winter. Some compounds such as 2-ethoxyethyl acetate were emitted by most species, others such as 3-hexen-1-ol, phenol or decanal were significantly emitted only by few species. The greatest diversity of emitted non-terpenoid C6-C10 VOCs was observed in spring and in Q. ilex. Temperature seemed a strong driver of these seasonal changes but other species-specific and seasonal factors seem involved. These results indicate that C6-C10 non-terpenoid VOCs contribute a rather significant fraction of the total biogenic VOC flux from these Mediterranean species, especially in spring and summer, and therefore should be considered in VOC emission inventories and in model predictions of tropospheric chemistry.     

Dietary habits associated with the presence of organochlorine pesticides in human milk

Abstract

This study aims to establish the relationship between the consumption of certain foods and the presence of organochlorine pesticides in human milk. A total of 167 samples of breastmilk were collected. Sample analysis was carried out by gas chromatography with electron capture detector. Pesticide concentrations (op’DDT, pp’DDT, pp’DDE, Σ-DDT, HCB, β-HCH) were grouped by consumption level of fish, dairy products, meat, eggs, and seafood and then were compared to each other. The odds ratio (OR) was calculated between the concentration of pesticides (higher and/or lower than median) and the exposure variable (high consumption). The results indicated low median concentrations of HCB, β???HCH, op’DDT and pp’DDT, whose fluctuations and trends between different frequencies of food consumption were not significant. pp’DDE and Σ???DDT values according to the increase in consumption of fish were significantly increased. Women with high fish consumption have a higher risk of high concentrations of pp’DDE and Σ-DDT (OR: high consumption: 5.6 (1.3–23.6). A protective effect was observed in the consumption of dairy products (β-HCH and op’DDT), meat (HCB), and seafood (pp’DDT). These results suggest that it is possible that the consumption of fish, dairy products, meat, and seafood influences the presence of organochlorine pesticides in the studied population.     

Effects of ozone on the foliar histology of the mastic plant (Pistacia lentiscus L.)

An open-top chamber study was conducted to investigate the tissue and cellular-level foliar effects of ozone (O3) on a Mediterranean evergreen species, the mastic plant (Pistacia lentiscus L.). Plants were exposed at three different O3 levels, and leaf samples were collected periodically from the beginning of the exposure. Although no visible foliar injury was evident, alterations of the plastids and vacuoles in the mesophyll were observed. Senescence processes were accelerated with an anomalous stacking of tannin vacuoles, and a reduction in the size and number of the chloroplasts. Overall, most of the modifications induced by O3 were consistent with previously reported observations on deciduous broadleaf species, with the exception of alterations in the cells covering the secretory channels, reported here as a new finding. Comments on the feasibility of using microscopy to validate O3 related field observations and subtle foliar injury are also given.     

Chemical oxidation of wastewater from molasses fermentation with ozone

Color removal from biologically pre-treated molasses wastewater by means of chemical oxidation with ozone has been investigated. Batch experiments have been performed in order to analyze the influence of ozone dosage and reaction time on color removal, molecular weight distribution and decolorization kinetics. Depending on the applied ozone dosage, color removal from 71% to 93% and COD reduction from 15% to 25% were reached after 30 min reaction time. TOC values remained constant throughout ozonation. Gel permeation chromatography corroborated that high molecular weight compounds, responsible for the brown color, were present in raw wastewater. UV spectral studies confirmed that these colored compounds were melanoidins. As a result of ozonation the concentration of chromophore groups decreased. Ozonation of synthetic melanoidin under the same experimental conditions provided similar color removal efficiencies. Pseudo-first order kinetics with respect to colored compounds were found.     

Impaired glutathione redox status is associated with decreased survival in two organophosphate-poisoned marine bivalves

Biomonitoring organophosphate (OP) exposure in marine environments is generally achieved by the measurement of acetylcholinesterase activity in bivalves like mussels. However, there is evidence that indicates that oxidative stress may be implied in OP toxicity. The aim of this study was to evaluate the relationship between survival from the OP insecticide fenitrothion and glutathione levels in marine bivalves. Mussels (Mytilus galloprovincialis Lam.) and scallops (Flexopecten flexuosus Poli) were exposed, in a time to death test, to their LC85 of fenitrothion for 96 h. OP-poisoned mussels showed reduced (GSH) and oxidised (GSSG) glutathione depletion in the digestive gland, muscle and gills. Pectinid spats exposed to this insecticide presented GSH depletion in the digestive gland and mantle, and a reduction of the GSH/GSSG ratio in gills and mantle. Although survival curves were significantly different and mussels withstood twice as much fenitrothion as pectinid spats, muscular GSH/GSSG ratio was highly related to mortality in both species. We suggest that an impairment in the glutathione redox status could result in an induction of the cell death, either by apoptosis or necrosis, leading ultimately to the death of the organism. We conclude that whereas glutathione depletion can be used as a biomarker of exposure, the muscular GSH/GSSG ratio might be used as a biochemical marker of effect and individual susceptibility to mortality of marine bivalves exposed to fenitrothion or other pollutants that induce oxidative stress.     

Variables affecting efficiency of molasses fermentation wastewater ozonation

The main operating variables affecting ozonation efficiencies of wastewater from beet molasses alcoholic fermentation have been studied. Semibatch experiments have been performed in order to analyze the influence of pH, bicarbonate ion, temperature and stirring rate on color and organic matter removals. The efficiencies were similar regardless of the pH, which indicates that direct reactions of ozone with wastewater organics were predominant to radical reactions. Gel permeation chromatography confirmed the reduction in the concentration of organics absorbing light at 475 nm after ozonation. The elimination of bicarbonate ion, strong inhibitor of hydroxyl radical reactions, yielded an improvement in both color and COD reduction efficiencies. Acidification for removing bicarbonate ions produced a shift of colored compounds to smaller molecular weights. The highest efficiencies were achieved at 40 degrees C. Color and COD reductions at 40 degrees C were about 90% and 37%, respectively. In no case, the percentage of TOC removed was higher than 10-15%. Stirring rate had a slightly positive effect during the first stage of the ozonation showing that mass transfer played a role only during the initial reaction phase when direct attack of ozone molecules to aromatic/olefinic structures of colored substances was the predominant pathway.