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PubMed2005

An interdisciplinary physical-chemical approach for characterization of arsenic in a calciner residue dump in Cornwall (UK).

During the later stages of hard-rock mining in Cornwall, UK, widespread processing and refining of arsenic in purpose-built calciners resulted in severe, localized contamination of soils with arsenic. Several physical-chemical techniques were applied to characterize arsenic in a calciner residue dump: X-ray powder diffraction (XRD), sequential extraction combined with hyphenated speciation methods, and X-ray absorption spectroscopic (XAS) methods such as XANES (X-ray absorption near-edge structure) and EXAFS (extended X-ray absorption fine structure). Arsenic was predominantly present in pentavalent form, bound to amorphous or poorly-crystalline hydrous oxides of Fe (probably alpha-hematite). A small amount of a non-classified crystalline iron arsenate phase was found, viz. Fe2(As(AsO4)3). There was also evidence for the presence of some arsenate bound to quartz (alpha-SiO2). The overall results make us believe that the normally assumed relative safety, from a mobility point of view, is questionable since only a small fraction of arsenic is found in a crystalline iron arsenate form.

Arsenic↗
PubMed2004

Modeling of adhesion in tablet compression. II. Compaction studies using a compaction simulator and an instrumented tablet press.

Adhesion problems are usually not identified until prolonged compression runs are studied near the end of the drug development process. During tablet manufacturing, adhesion problems encountered are usually addressed by statistically designed experiments based on experience. It would be a significant benefit for the pharmaceutical industry if adhesion problems could be identified early in drug development based on molecular considerations of the drug substance and/or prototype formulations. Drug substance-punch face interactions were reported in the first of the articles in this series, and focused on the elucidation of adhesion problems in tablet compression. It was hypothesized that the intermolecular interactions between drug molecules and the punch face was the first step (or criterion) in the adhesion process, and that the rank order of adhesion during tablet compression should correspond with the rank order of these energies of interaction. That is, the interaction between the molecular structure of the drug and the metal surface determines the primary interaction event or relative potential for adhesion, while the mechanical processes and/or lubrication effects may subsequently impact the extent of adhesion. Molecular simulations and atomic force microscopy were used to establish the rank order of the work of adhesion of a series of profen compounds. The results predicted that the relative degree of drug substance-punch face adhesion should decrease in the order of ketoprofen > ibuprofen > flurbiprofen. In this study, the authors investigated whether the rank order of the work of adhesion established on the molecular level and interparticulate level holds true in the tableting environment by measuring tablet take-off force, ejection force, and visual observation of the punch surfaces for both pure drug compacts and formulated tablets. The compaction simulator was used for pure profen compacts, while the instrumented tablet press for formulated tablets. Due to the inability to extract the adhesion force component from the total ejection force measurement, tablet ejection force was not used as a criterion to judge the adhesion behavior of the model compounds. The criteria used for judgement of punch face adhesion were tablet take-off force and visual observation of the punch faces. The rank order of adhesion for both pure drug and formulated tablets was determined to follow the order of ketoprofen > ibuprofen > flurbiprofen. The effect of run time on adhesion behavior was also investigated. Therefore, the rank order of the punch-face adhesion tendencies for the series of profen compounds was determined, and found to agree with the data from the predictive methods reported in the first article.

Adhesiveness↗
PubMed2001

A study of iron mineral transformation to reduce red mud tailings.

This study examines the effects of iron mineral transformation in an aluminum extraction process on the settling behavior, and the physical and chemical properties of the resulting red mud slurry that must be disposed of. By producing a red mud with a higher solid content, the total volume of mud slurry will also be reduced for a given alumina production rate and more caustic soda will be recovered. The settling behavior and the mineralogical, physical, and physico-chemical properties of one bauxite and three red muds processed under varying conditions were analyzed based on examination of the iron mineral transformations. The properties of red muds derived from the same bauxite can differ markedly due to variations in operating conditions of the Bayer process, such as temperature and the addition of a reducing agent. The settling of red mud can be improved by converting goethite into hematite and/or magnetite to produce a mud of larger particle size, smaller specific surface area, and larger specific gravity, characteristics which reduce the total volume of mud slurry to be disposed of and which allow for less potential contamination from caustic soda. This study also found that the by-product--Bayer sodalite--has the high exchange capacity for Na+ that might contribute to the long-term environmental problems.

Aluminum Oxide↗
PubMed2006

Levels of cystathionine gamma lyase production by Geotrichum candidum in synthetic media and correlation with the presence of sulphur flavours in cheese.

Geotrichum candidum is a cheese-ripening agent with the potential to produce sulphur flavour compounds in soft cheeses. We aimed to develop an alternative test for predicting the aromatic (sulphur flavours) potential of G. candidum strains in soft cheese. Twelve strains of G. candidum with different levels of demethiolase activity (determined by a chemical method) in YEL-met (yeast extract, lactate methionine) medium were studied. We investigated cgl (cystathionine gamma lyase) gene expression after culture in three media - YEL-met, casamino acid and curd media - and then carried out sensory analysis on a Camembert cheese matrix. We found no correlation between demethiolase activity in vitro and cgl gene expression. Sensory analysis (detection of sulphur flavours) identified different aromatic profiles linked to cgl expression, but not to demethiolase activity. The RT-PCR technique described here is potentially useful for predicting the tendency of a given strain of G. candidum to develop sulphur flavours in cheese matrix. This is the first demonstration that an in vitro molecular approach could be used as a predictive test for evaluating the potential of G. candidum strains to generate sulphur compounds in situ (Camembert cheese matrix).

Cheese↗
PubMed2004

Wastewater treatment polymers identified as the toxic component of a diamond mine effluent.

The Ekati Diamond Mine, located approximately 300 km northeast of Yellowknife in Canada's Northwest Territories, uses mechanical crushing and washing processes to extract diamonds from kimberlite ore. The processing plant's effluent contains kimberlite ore particles (< or =0.5 mm), wastewater, and two wastewater treatment polymers, a cationic polydiallydimethylammonium chloride (DADMAC) polymer and an anionic sodium acrylate polyacrylamide (PAM) polymer. A series of acute (48-h) and chronic (7-d) toxicity tests determined the processed kimberlite effluent (PKE) was chronically, but not acutely, toxic to Ceriodaphnia dubia. Reproduction of C. dubia was inhibited significantly at concentrations as low as 12.5% PKE. Toxicity identification evaluations (TIE) were initiated to identify the toxic component of PKE. Ethylenediaminetetraacetic acid (EDTA), sodium thiosulfate, aeration, and solid phase extraction with C-18 manipulations failed to reduce PKE toxicity. Toxicity was reduced significantly by pH adjustments to pH 3 or 11 followed by filtration. Toxicity testing with C. dubia determined that the cationic DADMAC polymer had a 48-h median lethal concentration (LC50) of 0.32 mg/L and 7-d median effective concentration (EC50) of 0.014 mg/L. The anionic PAM polymer had a 48-h LC50 of 218 mg/L. A weight-of-evidence approach, using the data obtained from the TIE, the polymer toxicity experiments, the estimated concentration of the cationic polymer in the kimberlite effluent, and the behavior of kimberlite minerals in pH-adjusted solutions provided sufficient evidence to identify the cationic DADMAC polymer as the toxic component of the diamond mine PKE.

Acrylic Resins↗
PubMed2007

Solid-state cultures of Fusarium oxysporum transform aromatic components of olive-mill dry residue and reduce its phytotoxicity.

The present study mainly investigated the ability of solid-state cultures of the non-pathogenic Fusarium oxysporum strain BAFC 738 to transform aromatic components to reduce the phytotoxicity in olive-mill dry residue (DOR), the waste from the two-phase manufacturing process. Lignin, hemicellulose, fats and water-soluble extractives contents of DOR colonized by the fungus for 20 weeks were reduced by 16%, 25%, 71% and 13%, respectively, while the cellulose content increased by 25%. In addition, the ethyl acetate-extractable phenolic fraction of the waste was reduced by 65%. However, mass-balance ultra-filtration and size-exclusion chromatography experiments suggested that the apparent removal of that fraction, mainly including 2-(3,4-dihydroxyphenyl)ethyl alcohol and 2-(4-hydroxyphenyl)ethyl alcohol, was due to polymerization. Mn-peroxidase and Mn-independent peroxidase activities were found in F. oxysporum solid-state cultures, while laccase and aryl alcohol oxidase activities were not detected. Tests performed with seedlings of tomato (Lycopersicum esculentum L.), soybean (Glycine maximum Merr.), and alfalfa (Medicago sativa L.) grown on soils containing 6% (w/w) of bioconverted DOR (kg soil)(-1) showed that the waste's phytotoxicity was removed by 20 weeks-old fungal cultures. By contrast, the same material exhibited a high residual toxicity towards lettuce (Lactuca sativa L.).

Food-Processing Industry↗
PubMed2003

500 years of mercury production: global annual inventory by region until 2000 and associated emissions.

Since pre-industrial times, anthropogenic emissions of Hg have at least doubled global atmospheric Hg deposition rates. In order to minimize environmental and human health effects, efforts have been made to reduce Hg emissions from industries and power plants, while less attention has been paid to Hg mining. This paper is a compilation of available data on primary Hg production and associated emissions with regional and annual resolution since colonial times. Globally, approximately one million tons of metallic Hg has been extracted from cinnabar and other ores during the past five centuries, half already before 1925. Roughly half has been used for mining of gold and silver, but the annual Hg production peaked during a short period of recent industrial uses. Comparison with total historic Hg deposition from global anthropogenic emissions (0.1-0.2 Mtons) suggests that only a few percent of all mined Hg have escaped to the atmosphere thus far. While production of primary Hg has changed dramatically over time and among mines, the global production has always been dominant in the region of the mercuriferous belt between the western Mediterranean and central Asia, but appears to be shifting to the east. Roughly half of the registered Hg has been extracted in Europe, where Spanish mines alone have contributed one third of the world's mined Hg. Approximately one fourth has been mined in the Americas, and most of the remaining registered Hg in Asia. However, the Asian figures may be largely underestimated. Presently, the dominant Hg mines are in Almadén in Spain (236 t of Hg produced in 2000), Khaydarkan in Kyrgyzstan (550 t), Algeria (estimated 240 t) and China (ca. 200 t). Mercury by-production from mining of other metals (e.g. copper, zinc, gold, silver) in 2000 includes 48 t from Peru, 45 t from Finland and at least 15 t from the USA. Since 1970, the recorded production of primary Hg has been reduced by almost an order of magnitude to approximately 2000 t in the year 2000. Mining is thus still of similar magnitude as all current anthropogenic Hg emissions to the atmosphere, and mined Hg may account for more than one third of these emissions. Also before use, mercury is emitted from Hg mines locally during the mining and refining processes and from mining waste. Global direct emissions to the atmosphere amount to 10-30 t per year currently (up to 10 at Almadén alone), and probably exceed 10000 t historically. Termination of Hg mining will reduce associated local emissions to the atmosphere and biosphere. Since several economically viable Hg-free alternatives exist for practically all applications of Hg, the production and use of Hg can be further reduced and all primary production of Hg other than by-production terminated.

Data Collection↗
PubMed2004

Behaviour of simazine in soil amended with the final residue of the olive-oil extraction process.

Addition of organic wastes to agricultural soils is becoming a common practice as a disposal strategy and to improve the physical and chemical soil properties. However, in order to optimise the use of organic wastes as soil amendments, their effect on the behaviour of other compounds that are also used in agriculture, such as pesticides, needs to be assessed. In this work, we have investigated the effects of the addition of the final solid residue of the new technology of olive-oil extraction (extracted alperujo or solid olive-mill waste, SOMW2) on the sorption, degradation and leaching of the herbicide simazine in a sandy loam soil. The results are compared with those of a previous study, where the intermediary by-product of the olive-oil processing technology (unextracted alperujo or SOMW1) was applied to the same soil. The soil was amended in the laboratory with SOMW2 at two different rates (5% and 10% w/w). Simazine sorption isotherms showed a great increase in herbicide sorption after SOMW2 addition to soil. SOMW2 addition also increased sorption irreversibility. Incubation studies revealed reduced biodegradation of simazine in the soil amended with SOMW2 compared to the unamended soil. Breakthrough curves of simazine in handpacked soil columns showed that SOMW2 addition retarded the vertical movement of the herbicide through the soil and greatly reduced the amount of herbicide available for leaching. Interestingly, the results were quantitatively different from those obtained for the intermediary by-product SOMW1, illustrating the importance of the specific characteristics of the organic amendment in determining its effect on pesticide behaviour.

Adsorption↗
PubMed2005

Behavioural treatment for chronic low-back pain.

BACKGROUND: Behavioural treatment, commonly used in the treatment of chronic low-back pain (CLBP), is primarily focused at reducing disability through the modification of environmental contingencies and cognitive processes. In general, three behavioural treatment approaches are distinguished: operant, cognitive and respondent. OBJECTIVES: To determine if behavioural therapy is more effective than reference treatments for CLBP, and which type of behavioural treatment is most effective. SEARCH STRATEGY: We searched the CENTRAL, MEDLINE, EMBASE, and PsycLIT databases up to October 2003. References of identified randomised trials and relevant systematic reviews were screened. SELECTION CRITERIA: Only randomised trials on behavioural treatment for non-specific CLBP were included. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed the methodological quality and extracted the data. The magnitude of effect was assessed by computing a pooled effect size for post-treatment and long-term results for each comparison, for each domain (i.e., behavioural outcomes, overall improvement, back pain specific and generic functional status, return to work, and pain intensity) using the random effects model. MAIN RESULTS: Seven studies (33%) were considered high quality. Comparing behavioural treatment to waiting list control (WLC) revealed strong evidence (4 trials, 134 people) in favour of a combined respondent-cognitive therapy for a medium positive effect on pain, and moderate evidence (2 trials, 39 people) in favour of progressive relaxation for a large positive effect on pain and behavioural outcomes (short-term only). When comparing operant treatment to WLC no significant differences could be detected on general functional status (strong evidence: 2 trials, 87 people) or on behavioural outcomes (moderate evidence; 3 trials, 153 people) (short-term only). There is limited evidence (1 trial, 98 people) that a graded activity program in an industrial setting is more effective than usual care for early return to work and reduced long-term sick leave. There is limited evidence (1 trail, 39 people) that there are no differences between behavioural treatment and exercises. Finally, there is moderate evidence (6 trials, 210 people) that there are no significant differences in short-term and long-term effectiveness when behavioural components are added to usual treatment programs for CLBP (i.e. physiotherapy, back education) on pain, generic functional status and behavioural outcomes. AUTHORS' CONCLUSIONS: Combined respondent-cognitive therapy and progressive relaxation therapy are more effective than WLC on short-term pain relief. However, it is unknown whether these results sustain in the long term. No significant differences could be detected between behavioural treatment and exercise therapy. Whether clinicians should refer patients with CLBP to behavioural treatment programs or to active conservative treatment cannot be concluded from this review.

Behavior Therapy↗
PubMed2004

Historical perspectives in gonadotrophin therapy.

The 20th century witnessed the steady development of knowledge about the reproductive process in animals and humans. These advances led to the identification of higher centres governing the dynamics of ovarian function and to the discovery of gonadotrophic hormones. As the mechanisms of action of these hormones became increasingly understood, they began to be used in the management of infertility during the early 1930s. Hormone extracts were originally prepared from animal pituitaries and pregnant mare serum, as well as from human pituitaries, placenta and urine, with pregnancies reported following their use in the late 1930s. This review traces the constant quest to reduce risks and improve safety and efficacy of hormone preparations for patients. It describes the complex path and perils leading to the pure hormone preparations that are available today, concluding with an optimistic glimpse towards the future. Small molecules that are orally active and specific are currently being investigated, some with the capacity to bypass many parts of the receptor conformation. Here lies the immediate future of this field, utilizing low-cost, small, defined molecules to stimulate follicle growth, ovulation and corpus luteum formation. Perhaps one day the classical gonadotrophins will no longer be required in clinical treatment.

Animals↗
PubMed2003

Solid-phase microextraction liquid chromatography/tandem mass spectrometry to determine postharvest fungicides in fruits.

A method to determine five postharvest fungicides (dichloran, flutriafol, o-phenylphenol, prochloraz, tolclofos methyl) in fruits (cherries, lemons, oranges, peaches) has been developed using solid-phase microextraction (SPME) coupled to liquid chromatography (LC) with photodiode array (DAD), mass spectrometry (MS), or tandem mass spectrometry (MS/MS) with ion trap detection. Extraction involved sample homogenization with an acetone/water solution (5:1), filtration, and acetone evaporation prior to fiber extraction. The pesticides were isolated with a fused-silica fiber coated with 50-microm Carbowax/template resin. The effects of pH, ion strength, sample volume, and extraction time were investigated, and their impact on the SPME-LC/MS was studied. Dynamic and static modes of desorption were compared and the variables affecting desorption processes in SPME-LC optimized. Static desorption provided the best recoveries and peak shapes. Recoveries at the limit of quantification (LOQ) levels were between 10% for prochloraz and 60% for o-phenylphenol, with relative standard deviations from 13.6% for prochloraz to 3.1% for o-phenylphenol. The versatility of the method was also exhibited by its excellent linearity in the concentration intervals between 0.0005 and 5 mg kg(-1) for dichloran and 0.01-10 mg kg(-1) for tolclofos methyl and prochloraz. LOQs ranged from 0.25 to 1 microg g(-1) using DAD, from 0.002 to 0.01 microg g(-1) using LC/MS, and from 0.0005 to 0.01 to microg g(-1) using LC/MS/MS. LOQs obtained in the present study using LC/MS and LC/MS/MS are lower than maximum residue limits established for all the fungicides in any matrix studied. The method enables to determine polar pesticides at low-microgram per gram levels in fruits.

Calibration↗
PubMed2005

Hydrogen and ethanol production from glycerol-containing wastes discharged after biodiesel manufacturing process.

H2 and ethanol production from glycerol-containing wastes discharged after a manufacturing process for biodiesel fuel (biodiesel wastes) using Enterobacter aerogenes HU-101 was evaluated. The biodiesel wastes should be diluted with a synthetic medium to increase the rate of glycerol utilization and the addition of yeast extract and tryptone to the synthetic medium accelerated the production of H2 and ethanol. The yields of H2 and ethanol decreased with an increase in the concentrations of biodiesel wastes and commercially available glycerol (pure glycerol). Furthermore, the rates of H2 and ethanol production from biodiesel wastes were much lower than those at the same concentration of pure glycerol, partially due to a high salt content in the wastes. In continuous culture with a packed-bed reactor using self-immobilized cells, the maximum rate of H2 production from pure glycerol was 80 mmol/l/h yielding ethanol at 0.8 mol/mol-glycerol, while that from biodiesel wastes was only 30 mmol/l/h. However, using porous ceramics as a support material to fix cells in the reactor, the maximum H2 production rate from biodiesel wastes reached 63 mmol/l/h obtaining an ethanol yield of 0.85 mol/mol-glycerol.

Bioreactors↗
PubMed1994

Mutagenicity of coal-dust and smokeless-tobacco extracts in Salmonella typhimurium strains with differing levels of O-acetyltransferase activities.

Epidemiological studies have indicated an increased incidence of gastric neoplasia in coal miners. Because smokeless tobacco use is prevalent in the mining industry, nitrites or other components of these products may be etiologically associated with these gastric neoplasms. In this study both nitrosated and non-nitrosated coal-dust (from West Virginia and New Mexico) as well as smokeless-tobacco (snuff and chewing tobacco) extracts were examined for the presence of aromatic amines and nitroarenes by comparing the activities of these extracts in the pre-incubation variant of the Ames assay. Salmonella strains with differing O-acetyltransferase activities (TA98 and YG1024) were utilized in this investigation. The results of the examination of the coal-dust extracts indicated positive activity only in the nitrosated extracts. Both nitrosated extracts elicited an increased number of revertants (2-4-fold) on YG1024 without S9 in comparison to TA98, suggesting the presence of nitroarenes in these extracts. Additionally, the nitrosated West Virginia coal extract showed higher levels of activity on YG1024 with S9, indicating the possible presence of aromatic amines in this complex mixture. The non-nitrosated smokeless-tobacco extracts showed activity only on YG1024 in the presence of S9, with the highest amount of activity occurring in the snuff sample. Except for the chewing-tobacco extract on TA98 without S9, positive activity was found in both nitrosated tobacco extracts on YG1024 and TA98. As with the coal extracts, the presence of nitroarenes was inferred for these nitrosated materials. A comparative study of the non-nitrosated snuff extract across 5 tester strains with varying sensitivities to aromatic amines and nitroarenes (TA98NR, TA98/1,8-DNP6, TA98, YG1021 and YG1024) indicated that aromatic amines were a probable source of the mutagenic activity. The curing process and/or the addition of certain flavorants are potential sources of the mutagenic aromatic amines suggested to be present in the non-nitrosated snuff extract. These findings are consistent with an etiologic role supplementary to the nitroso compounds for mutagenic nitroarenes and aromatic amines in the development of gastric neoplasia in coal miners.

Acetyltransferases↗
PubMed2002

Fenarimol solar degradation pathways and photoproducts in aqueous solution.

The degradation photoproducts of the fungicide fenarimol obtained from irradiation of aqueous solutions with sunlight were characterised. The photoproducts resulting from samples with different exposure times were extracted and separated using chromatographic techniques. Seven main photoproducts were detected using high performance liquid chromatography with a photodiode array detector, gas chromatography with mass spectrometry detector and Fourier transform infrared spectroscopy. Structures are suggested for possible photoproducts based on the characterisation results, minimum energy geometry of the parent compound, and the mass spectral behaviour of fenarimol. These correspond to the compounds with m/z 328 (three structural isomers (a), (b) and (c)), m/z 294 (two structural isomers (a) and (b)), m/z 292, 278 and 190. Of the various major products detected, the isomer 328(a) is seen to be particularly unstable under the action of sunlight. The most stable photoproducts are found to be those with m/z 294(a), 278 and 190. However, upon prolonged solar irradiation all of these break down to produce polar, low molecular weight compounds. Comparison with our own and other results on fenarimol photolysis indicate significant solvent effects on the process. The combination of these structural characterisation results and previous data from spectroscopic and photodegradation kinetics studies allows us to suggest some possible mechanisms for the photodegradation of fenarimol under sunlight.

Fungicides, Industrial↗
PubMed2005

Investigation of an acetate-fed denitrifying microbial community by stable isotope probing, full-cycle rRNA analysis, and fluorescent in situ hybridization-microautoradiography.

The acetate-utilizing microbial consortium in a full-scale activated sludge process was investigated without prior enrichment using stable isotope probing (SIP). [13C]acetate was used in SIP to label the DNA of the denitrifiers. The [13C]DNA fraction that was extracted was subjected to a full-cycle rRNA analysis. The dominant 16S rRNA gene phylotypes in the 13C library were closely related to the bacterial families Comamonadaceae and Rhodocyclaceae in the class Betaproteobacteria. Seven oligonucleotide probes for use in fluorescent in situ hybridization (FISH) were designed to specifically target these clones. Application of these probes to the sludge of a continuously fed denitrifying sequencing batch reactor (CFDSBR) operated for 16 days revealed that there was a significant positive correlation between the CFDSBR denitrification rate and the relative abundance of all probe-targeted bacteria in the CFDSBR community. FISH-microautoradiography demonstrated that the DEN581 and DEN124 probe-targeted cells that dominated the CFDSBR were capable of taking up [14C]acetate under anoxic conditions. Initially, DEN444 and DEN1454 probe-targeted bacteria also dominated the CFDSBR biomass, but eventually DEN581 and DEN124 probe-targeted bacteria were the dominant bacterial groups. All probe-targeted bacteria assessed in this study were denitrifiers capable of utilizing acetate as a source of carbon. The rapid increase in the number of organisms positively correlated with the immediate increase in denitrification rates observed by plant operators when acetate is used as an external source of carbon to enhance denitrification. We suggest that the impact of bacteria on activated sludge subjected to intermittent acetate supplementation should be assessed prior to the widespread use of acetate in the wastewater industry to enhance denitrification.

Acetates↗
PubMed2004

Mechanisms for solubilization of cobalt, copper and nickel from Indian Ocean nodules at near neutral pH by a marine isolate.

Polymetallic ocean nodules offer an alternative source for extracting valuable strategic metals like Cu, Co and Ni. A novel biodissolution process was carried out, employing the cell-free spent growth medium from a marine organism ( Bacillus M1) isolated from nodules; and Cu, Co and Ni solubilization from the nodules was observed to be beyond the theoretical solubility limits at near neutral pH. Different characterization techniques revealed the presence of phenolic substances in the spent growth medium, which might have formed soluble complexes with the transition metals. The low prevailing E(h) redox value in the medium suggested a strong reducing environment, favoring the reductive dissolution of the oxides. A correlation study of dissolution of Cu, Co and Ni with that of Mn and Fe in the nodules was made to investigate the mechanisms of metal solubilization by the marine isolate. Under the influence of a strong reducing environment coupled with complexation by a phenolic substance present in the spent growth medium, Mn and Fe oxides were solubilized from the nodules, resulting in concomitant dissolution of Cu, Co and Ni associated with them in the nodules.

Bacillus↗
PubMed2006

Electrical discharge machining: occupational hygienic characterization using emission-based monitoring.

Hazardous potential in industrial environments is normally assessed by means of immission-based sampling and analyses. This approach is not adequate, if effects of specific technical adjustments at machine tools or working processes on hygienic parameters should be assessed. This work has focused on the optimization of a manufacturing process (electrical discharge machining, EDM), with regard to risk reduction assessment. It is based on emission analyses rather than immision analyses. Several technical EDM parameters have been examined for their influence on air-based emissions. Worktools and workpieces used have a strong influence on aliphatic compounds and metals but not on volatile organic compounds (benzene, toluene, ethylene-benzene and xylene (BTEX)) and polycyclic aromatic hydrocarbons (PAHs) in air emissions. Increasing the dielectric (mineral oil) level above processing location decreases BTEX, chromium, nickel and PAH emissions. Aliphatic compounds, in contrast, increase in air emissions. EDM current used has a positive relationship with all substances analyzed in air emissions. Indicative immission concentrations, as can be expected under EDM conditions, are estimated in a predictive scenario. The results of this characterization give rise to an important conclusion in that risk assessment so far has been using incorrect parameters: total aliphatic compounds. Maximum level of chromium is reached long before limit values of aliphatic compounds are exceeded. Because of the fact that metals, like chromium, also have a higher hazardous potential, metal analysis should be introduced in future risk assessment. This experimental approach, that captures total emission of the electrical discharge machine, and is not solely based on immission values, has lead to a better understanding of the production process. This information is used to extract recommendations regarding monitoring aspects and protection measures.

Air Pollutants, Occupational↗
PubMed2005

The use of a sequential leaching procedure for heavy metal fractionation in green liquor dregs from a causticizing process at a pulp mill.

A five-stage sequential leaching procedure was used to fractionate heavy metals (Cd, Cu, Pb, Cr, Zn, Fe, Mn, Ni, Co, As, V, Ba and Ti) in green liquor dregs into the following fractions: (1) water-soluble fraction (H2O), (2) exchangeable fraction (CH3COOH), (3) easily reduced fraction (HONH3Cl), (4) oxidizable fraction (H2O2 + CH3COONH4), and (5) residual fraction (HF + HNO3 + HCl). The green liquor dregs were derived from a causticizing process at a pulp mill at Kemi, Northern Finland. According to the leaching studies, the leachability of heavy metals in the water-soluble fraction varied between 0.5 and 2 mg kg(-1) expressed on a dry weight (d.w.) basis, indicating relatively low bioavailability of the metals. However, the concentration of Mn (2065 mg kg(-1); d.w.) showed a strong and of Zn (17.6 mg kg(-1); d.w.), Ni (39.7 mg kg(-1); d.w.) and Ba (32.0 mg kg(-1); d.w.) slightly tendency to be extracted in the exchangeable fraction. In addition, Zn, Mn, Ni, Co, V and Ba showed clear leachability in the easily reduced fraction, as well as Cd, Cu, Cr, Zn, Mn, As and Ba in the oxidizable fraction. For Cd, Cu, Cr, Zn, Mn, Ni, Co, Ba and Ti, the sum of leachable heavy metal concentrations in fractions 1-5 agreed relatively well with the "total" heavy metal concentrations. Recoveries of the sum of fractions 1-5 were 84-56% of those obtained by the US EPA method 3052 (i.e. concentrations obtained after microwave oven digestion with a mixture of HF and HNO3).

Chemical Fractionation↗