SEM-EDX analysis in the source apportionment of particulate matter on Hypogymnia physodes lichen transplants around the Cu smelter and former mining town of Karabash, South Urals, Russia

Scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX) of particulate matter on lichen transplant thalli (Hypogymnia physodes) was assessed as a complementary technique to wet chemical analysis for source apportionment of airborne contaminants. Transplants (2 month exposure) stationed in the Cu smelter and former mining town of Karabash were compared with those from a control site 30 km south. Particulate matter in Karabash samples (715 analyses) showed higher levels of S, Pb, Cu, Sn and Zn compared with the control (598 analyses). Complex element associations among the particles confounded detailed mineralogical identifications, and therefore a simplified particle classification scheme was devised for source apportionment. Karabash samples contained high levels of particles classified as mining-related (MRP), and these were also identified in control samples, indicating wide spatial dispersion from the smelter and highlighting the sensitivity of the method. It was noted that MRP <2.5-microm diameter were poorly represented on lichen surfaces suggesting this may limit the usefulness of Hypogymnia transplants as proxies when assessing human health impacts from airborne particulates. Analyses of the lichen thallus surface (away from surface particulates) revealed high levels of Cu, Zn, Fe and Pb associated with organics in the Karabash samples compared with the control, with a proportionate loss of K, interpreted as being due to a stress-related increase in cell membrane permeability. This type of analysis may provide a novel SEM-EDX-based method for assessing lichen vitality. The techniques developed are presented and further implications of the study are discussed.     

Biofilm quantification on stone surfaces: comparison of various methods

In the present study, the efficacy of three different methods of estimating biofilm biomass on stone (amount of chlorophyll a, fluorescein diacetate hydrolysis and changes in colour) is discussed. Stone samples were sprayed with solutions of cyanobacteria and the actual microbial biomass--determined by cell culture--was compared with the biomass estimated using the different methods. Statistically significant differences between actual biomass and that estimated from the fluorescein diacetate hydrolysis method invalidate its use. However, although the results indicated the amount of chlorophyll to be a good estimator of biofilm biomass, problems in the total extraction of chlorophyll from the stone cannot be overlooked. Determination of changes in colour was found to be a good method of quantifying biofilms growing on stone.     

Mechanical behavior of micaceous clays

This study aims to investigate the effect of mica content on the mechanical properties of clays.Commercially available ground mica was blended with a locally available clayey soil,at varying nica contents by mass of 5%,10%,15%,20%,25% and 30%,to artificially prepare various micaceous clay blends.The preliminary testing phase included consistency limits and standard Proctor compaction tests.The primary testing program consisted of unconfined compression(UC),direct shear(DS) and scanning electron microscopy(SEM) tests.The test results showed that the liquid and plastic limits exhibited a linear,monotonically increasing trend with increase in mica content.The rate of increase in the plastic limit,however,was found to be greater than that of the liquid limit,thereby leading to a gradual transition towards a non-plastic,cohesionless character.The soft,spongy fabric and high water demand of the mica mineral led to higher optimum water contents and lower maximum dry unit weights with increasing mica content.Under low confinement conditions,i.e.the UC test and the DS test at low normal stresses,the shear strength was adversely affected by mica.However,the closer packing of the clay and mica components in the matrix under high confinement conditions offsets the adverse effects of mica by inducing frictional resistance at the shearing interface,thus leading to improved strength resistance.     

Structural reliability software at the University of California, Berkeley

The paper provides an overview of three software for structural reliability analysis developed at the University of California, Berkeley. These are CalREL, which is a general-purpose structural reliability code written in FORTRAN; FERUM, which is a collection of Matlab^® files that can be used for structural reliability analysis in conjunction with simple finite element models; and OpenSees, which is an object-oriented code for nonlinear structural response simulation with reliability capabilities. Reliability analysis methods featured by these software include FORM, SORM, Monte Carlo simulation, and various importance sampling methods. In addition, variable importance and sensitivity measures are provided.     

Environmental exposure to lead and its correlation with biochemical indices in children

Lead is a global concern because of its ubiquity in the environment and known to be associated with abnormal neurobehavioral and cognitive development of young children. There is no study from India to describe a composite profile of blood lead and its biochemical influences in children. The present study was aimed at determining the proportion of children with >10 mug/dL blood lead levels (BLLs), association between BLLs, and sociodemographic characteristics, if any, and alterations in biochemical indices in the blood as an underlying mechanism of lead intoxication. A total of 62 children (4--12 y) of Lucknow and nearby areas were recruited to determine BLLs, delta-amimolevulinic acid dehydratase (delta-ALAD) activity, catalase (CAT) activity, and malondialdehyde (MDA) and glutathione (GSH) levels in the blood. Mean level of blood lead was 7.47+/-3.06 microg/dL (2.78--15.0) and 29%-exceeded 10 microg/dL, CDC intervention level. The BLLs were found to be significantly influenced by social status, area of residence, source of water supply, maternal educational status (p<0.001), type of house, and proximity to traffic density (p<0.01). delta-ALAD was significantly lower in the group of children with BLLs 11.39+/-1.39 microg/dL when compared to children with BLLs 7.11+/-1.25 microg/dL and 3.93+/-0.61 microg/dL (p=0.0007, 0.0005, respectively). However, CAT activity was higher in the groups of children with higher blood levels than with lower BLLs (p=0.0159, 0.0001, respectively). There was an increase in MDA level with a concomitant decrease of GSH in children with BLLs 11.39+/-1.39 microg/dL compared with those of children with BLLs 7.11+/-1.25 microg/dL and 3.93+/-0.61 microg/dL (p=0.0001, 0.0002, and p=0.0001, respectively). There was statistically significant correlation of BLLs with delta-ALAD (r=-0.44, p=0.00035), MDA (r=0.46, p=0.00018), GSH (r=-0.62, p=0.00001), and CAT (r=0.44, p=0.00035). Significantly, CAT activity, MDA, and GSH levels were in turn, found to be correlated with delta-ALAD (r=-0.45, p=0.00024; r=-0.43, p=0.00053; r=0.43, p=0.00053, respectively). Results of the present study indicate a declining trend of BLLs in children when compared with those reported from metropolitan cities of India when leaded gasoline was in practice and that the BLLs were significantly associated with biochemical indices in the blood which have the potential to be used as biomarkers of lead intoxication.     

Microbial activity and distribution during enhanced contaminant dissolution from a NAPL source zone

Laboratory experiments were conducted to assess microbial reductive dechlorination in one-dimensional sand columns containing a 10 cm long source zone of uniformly distributed residual tetrachloroethene (PCE) nonaqueous phase liquid (NAPL), a 10 cm long transition zone directly down-gradient of the source zone containing some nonuniformly distributed NAPL ganglia, and a 40 cm long plume region down-gradient of the transition zone. The activity and distribution of Sulfurospirillum multivorans, a PCE-to-1,2-cis-dichloroethene (cis-DCE) dechlorinating bacterium, was evaluated in columns containing either a mixed-NAPL (0.25 mol/mol PCE in hexadecane) or pure PCE-NAPL. Significant dechlorination of PCE to cis-DCE was observed in the mixed-NAPL column, resulting in 53% PCE-NAPL mass recovery in the effluent with PCE-NAPL dissolution enhanced by up to 13.6-fold (maximum) and 4.6-fold (cumulative) relative to abiotic dissolution. Quantitative real-time PCR targeting pceA, the PCE reductive dehalogenase gene of S. multivorans, revealed that S. multivorans cells were present in the NAPL source zone, and increased in numbers (i.e., grew) throughout the source and transition zones. In contrast, minimal reductive dechlorination and microbial growth were observed in the column containing pure PCE-NAPL, where aqueous-phase PCE concentrations reached saturation. These results demonstrate that microbial growth within NAPL source zones is possible, provided that contaminant concentrations remain below levels toxic to the dechlorinating organisms, and that microbial growth can result in significant bioenhanced NAPL dissolution.     

Radionuclide contamination of foods imported into Iraq following the Chernobyl nuclear reactor accident

Since early 1986, a monitoring program for radionuclides in imported foods has been carried out by the Iraqi Atomic Energy Commission. After the Chernobyl nuclear reactor accident in the Soviet Union, the program was expanded; our laboratory was officially designated by the Iraqi Government to measure radionuclide activity concentrations in foodstuff imported from countries known to be severely contaminated by Chernobyl radioactive fallout. Gamma-spectrometric analysis was used. Food items such as powdered milk, lamb meat, poultry, cereals and grains imported into Iraq before the Chernobyl accident did not contain any detectable fission products. However, all lamb meat, 81% of the lentil, 44% of the powdered milk and chick-pea, and 17% of the roast beef samples were contaminated with 137Cs or 134Cs and 137Cs. The highest 137Cs contamination levels found were 82, 147, 420, 6 and 4 Bq kg-1, respectively. Contamination by 134Cs was approximately 50% of the values given above.     

The acute effect of bunker C oil and an oil dispersant on: 1 Serum glucose, serum sodium and gill morphology in both freshwater and seawater acclimated rainbow trout (Salmo gairdneri)

Bunker C oil and an oil dispersant were tested for physiological stress on both freshwater and saltwater acclimated rainbow trout. Both compounds tended to reduce serum glucose levels with Bunker C causing the more significant decrease (P < 0.08), indicating a possible dysfunction of the kidney. The freshwater treatment group showed a significant decrease in sodium levels (P < 0.01) when treated with a dispersant, while under similar conditions, saltwater acclimated fish show a very marked increase in serum sodium concentrations (P < 0.025). Those fluctuations in sodium levels are resultant from direct interference with the energy activated sodium transport systems of the gills. Microphotographs of gill filaments and lamellae show severe damage caused by the dispersant and dispersant/oil mixture with less impairment resultant from Bunker C exposure.