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PubMed2005

Effects of a reactive barrier and aquifer geology on metal distribution and mobility in a mine drainage impacted aquifer.

The Nickel Rim aquifer has been impacted for five decades by a metal-rich plume generated from the Nickel Rim mine tailings impoundment. Metals released by the oxidation of pyrrhotite in the unsaturated zone of the tailings migrate into the downgradient aquifer, affecting both the groundwater and the aquifer solids. A reactive barrier has been installed in the aquifer to remove sulfate and metals from the groundwater. The effect of the reactive barrier on metal concentrations in the aquifer solids has not previously been studied. In this study, a series of selective extraction procedures was applied to cores of aquifer sediment, to ascertain the distribution of metals among various solid phases present in the aquifer. Extraction results were combined with groundwater chemistry, geochemical modelling and solid-phase microanalyses, to assess the potential mobility of metals under changing geochemical conditions. Reactions within the reactive barrier caused an increase in the solid-phase carbonate content downgradient from the barrier. The concentrations of poorly crystalline, oxidized phases of Mn and Fe, as well as concentrations of Cr(III) associated with oxidized Fe, and poorly crystalline Zn, are lower downgradient from the barrier, whereas total solid-phase metal concentrations remain constant. Iron and Mn accumulate as oxidized, easily extractable forms in a peat layer overlying the aquifer. Although these oxides may buffer reducing plumes, they also have the potential to release metals to the groundwater, should a reduced condition be imposed on the aquifer by remedial actions.

Biodegradation, Environmental↗
PubMed2006

Evaluation of municipal wastewater treatment plants with different technologies at Las Rozas, Madrid (Spain).

Eight small-scale municipal wastewater treatment plants were evaluated over a period of 19 months in the suburb of Las Rozas in Madrid (Spain). Four plants used compact extended aeration, two used conventional activated sludge, two used conventional extended aeration, one used a rotary biodisc reactor and the other used a peat bed reactor. The best results were obtained from the plants that used conventional technologies and the biodisc. Conventional activated sludge and extended aeration had higher removal efficiencies for ammonia, TSS, COD and BOD(5) and produced good quality final effluents for final disposal in accordance with the discharge standard. Empirical equations that correlated the concentration of dissolved oxygen in the effluents with the efficiencies of TSS, ammonia, COD and BOD(5) removals for all plants evaluated were obtained. The performance of the plants using compact extended aeration was affected more than those using conventional technologies or rotary biodisc when the capacity exceeded that of its initial design.

Evaluation Studies as Topic↗
PubMed2004

Lake fish as the main contributor of internal dose to lakeshore residents in the Chernobyl contaminated area.

Two field expeditions in 1996 studied 137Cs intake patterns and its content in the bodies of adult residents from the village Kozhany in the Bryansk region, Russia, located on the shore of a drainless peat lake in an area subjected to significant radioactive contamination after the 1986 Chernobyl accident. The 137Cs contents in lake water and fish were two orders of magnitude greater than in local rivers and flow-through lakes, 10 years after Chernobyl radioactive contamination, and remain stable. The 137Cs content in lake fish and a mixture of forest mushrooms was between approximately 10-20 kBq/kg, which exceeded the temporary Russian permissible levels for these products by a factor of 20-40. Consumption of lake fish gave the main contribution to internal doses (40-50%) for Kozhany village inhabitants Simple countermeasures, such as Prussian blue doses for dairy cows and pre-boiling mushrooms and fish before cooking, halved the 137Cs internal dose to inhabitants, even 10 years after the radioactive fallout.

Agaricales↗
PubMed2004

Prospects for cleaning ash in the acidic effluent from bioleaching of sulfidic concentrates.

Leaching of ashes in sulfuric acid (pH 1.0, liquid-to-solid (L/S) ratio 10:1, 25 degrees C) has been characterized with respect to the neutralizing capacity and the dissolution of dominant ions and trace elements. The conditions mimic the oxidation stage of a biohydrometallurgical process for base metal production from sulfidic mineral concentrates. Direct acid leaching of ash, integrated with this metallurgical process, offers a feasible route to the sustainable handling of metal-rich ashes. The treated ash will be deposited together with the inert mineral residue. Cd, Co, Cu, Ni and Zn are effectively leached and can be recovered utilizing existing hydrometallurgical technology, but the recovery of other readily dissolved metals, notably Mn, U and V, requires that additional steps are implemented. We make two recommendations for industrial processes. The first is to replace limestone with ash from biofuels, except peat, for pH control in biohydrometallurgical processing. This requires a modest increase of fresh alkali compared with limestone. The second is to implement sulfuric acid leaching of fly ash from the combustion of solid waste and other metal-rich fuels (used wood, tires), thereby avoiding costly ash-deposits. There is a significant economic incentive for these changes, since no costly ash-deposits and less limestone will be needed.

Hazardous Waste↗
PubMed2004

The effect of surfactants on the distribution of organic compounds in the soil solid/water system.

The efficiency of soil remediation by surfactant washing was evaluated via the measured distribution coefficients of a number of nonpolar compounds in several soil-water mixtures. The studied compounds (contaminants) are BTEX (benzene, toluene, ethylbenzene, and p-xylene) and three chlorinated pesticides (lindane, alpha-BHC, and heptachlor epoxide), which span several orders of magnitude in water solubility (S(w)). A peat, and two natural soils were used that comprise a wide range in soil organic matter (SOM) content. The surfactants tested included cationic, anionic and nonionic types, with concentrations up to five to six times the critical micelle concentration (CMC). The K(d)(*)/K(d), values were used to evaluate the remediation efficiency under various operation conditions. For relatively water soluble BTEX compounds, the surfactant adsorption on the soil surface is the deciding factor on contaminant desorption from soil. For the less-soluble pesticides, surfactant micelles in solution influence the contaminant desorption more. The contaminants partitioning to SOM or adsorbed surfactants lowers the desorption efficiency. Anionic surfactants are found to be a better choice on soil remediation because they do not form admicelle on soil surface that enhances the SOM content. Cationic surfactant, which adsorb onto soil surfaces, leads to poor remediation efficiency. An improper selection of surfactant would result in inefficiency in soil remediation by surfactant washing.

Absorption↗
PubMed2005

Kinetics of heavy metal uptake by vegetation immobilized in a polysulfone or polycarbonate polymeric matrix.

The ability of four common vegetations - wood, grass, compost, and peat moss - to remove cadmium, chromium, and lead from dilute aqueous solutions is investigated. Dried ground vegetations are immobilized in polysulfone, and poly (bisphenyl A) carbonate to form spherical beads through a phase inversion process. The beads are contacted with a dilute aqueous solution containing metal ions of interest. The removal of metal ions from the solution is monitored over the course of the experiment and the first-order kinetics parameters estimated. The rates of removal as well as the equilibrium bead loadings are shown to be affected by both the choice of vegetation and the choice of polymer.

Cadmium↗
PubMed2005

Effect of shutdown on styrene removal in a biofilter inoculated with Pseudomonas sp. SR-5.

Styrene gas removal was carried out in a biofilter inoculated with a styrene-degrading Pseudomonas sp. SR-5 using a mixed packing material of peat and ceramic under the non-sterile condition. More than 86% removal efficiency was obtained at styrene load of 5-93 g m(-3) h(-1) for 62 days operation period and 78% carbon of removed styrene was converted to CO2. Thereafter, three kinds of styrene shutdown experiments were conducted: (i) air and mineral medium were supplied for 4 days, (ii) complete shutdown, namely no styrene, air and moisture supply was conducted for 3 days, and (iii) only air was supplied for 11 days. When styrene gas was re-supplied after (i) and (iii) shutdown experiments, styrene removal efficiency rapidly recovered, but after (ii) shutdown, recovery of styrene removal was significantly delayed. Supply of air during shutdown period was found to be enough to resume microbial activity to degrade styrene.

Biodegradation, Environmental↗
PubMed2006

Bioremediation of endosulfan contaminated soil and water -- optimization of operating conditions in laboratory scale reactors.

A mixed bacterial culture consisted of Staphylococcus sp., Bacillus circulans-I and -II has been enriched from contaminated soil collected from the vicinity of an endosulfan processing industry. The degradation of endosulfan by mixed bacterial culture was studied in aerobic and facultative anaerobic conditions via batch experiments with an initial endosulfan concentration of 50mg/L. After 3 weeks of incubation, mixed bacterial culture was able to degrade 71.58+/-0.2% and 75.88+/-0.2% of endosulfan in aerobic and facultative anaerobic conditions, respectively. The addition of external carbon (dextrose) increased the endosulfan degradation in both the conditions. The optimal dextrose concentration and inoculum size was estimated as 1g/L and 75mg/L, respectively. The pH of the system has significant effect on endosulfan degradation. The degradation of alpha endosulfan was more compared to beta endosulfan in all the experiments. Endosulfan biodegradation in soil was evaluated by miniature and bench scale soil reactors. The soils used for the biodegradation experiments were identified as clayey soil (CL, lean clay with sand), red soil (GM, silty gravel with sand), sandy soil (SM, silty sand with gravel) and composted soil (PT, peat) as per ASTM (American society for testing and materials) standards. Endosulfan degradation efficiency in miniature soil reactors were in the order of sandy soil followed by red soil, composted soil and clayey soil in both aerobic and anaerobic conditions. In bench scale soil reactors, endosulfan degradation was observed more in the bottom layers. After 4 weeks, maximum endosulfan degradation efficiency of 95.48+/-0.17% was observed in red soil reactor where as in composted soil-I (moisture 38+/-1%) and composted soil-II (moisture 45+/-1%) it was 96.03+/-0.23% and 94.84+/-0.19%, respectively. The high moisture content in compost soil reactor-II increased the endosulfan concentration in the leachate. Known intermediate metabolites of endosulfan were absent in all the above degradation studies.

Bacillus↗
PubMed2006

Studies on copper(II)- and zinc(II)-mixed ligand complexes of humic acid.

Interactions between humic acid (HA), extracted from Brazilian peat soil, and cations of copper(II) and zinc(II) have been examined by infrared spectroscopy, and electrochemical and thermogravimetric analyses. Spectral studies revealed that the interaction with metals occurred mainly at the carboxylic acid groups of HA. The stability constants of HA complexes formed with Cu(2+) and Zn(2+) were found, by square wave voltammetry and application of the Lingane model, to be 8.93 x 10(10) and 2.92 x 10(2), respectively. Thermal analysis indicated that the stability of HA was increased by the presence of divalent cations of copper and zinc.

Algorithms↗
PubMed2006

Competitive metal binding to a silicate-immobilized humic material.

The investigation of the competitive binding of metal ions to a biogenic material comprised of organic peat immobilized in a polysilicate matrix was undertaken. This material was packed into 5.0mL bed-volume columns using 40-60mesh size particles. Two separate mixtures of metal ions were studied by monitoring the solution pH and the concentration of each metal in the effluent as a function of the volume of influent introduced to the material. These mixtures contained either the metal ions Ca(2+), Mg(2+), and Cu(2+) or the ions Cu(2+), Hg(2+), and Pb(2+). A general order of binding affinities was determined to be Mg(2+)<Ca(2+)<<Cu(2+)<Pb(2+)<Hg(2+). Comparisons of amounts of metal ions bound and protons released indicated the initial release of two protons for each divalent metal ion bound. However, prolonged exposure of the material to the metal solutions yielded a molar ratio of 1:1. This suggests the involvement of ion exchange sites followed by that of sites using an alternate binding mechanism. The presence of binding sites with varied mechanisms and metal ion affinities was further illustrated through the initial binding and subsequent release of lower affinity metal ions (e.g., Mg(2+) and Ca(2+)).

Adsorption↗
PubMed2006

Does hospital cleanliness correlate with methicillin-resistant Staphylococcus aureus bacteraemia rates?

Publicly available data for all National Health Service hospitals in England were used to examine whether there is a link between hospital cleanliness and rates of meticillin-resistant Staphylococcus aureus (MRSA) bacteraemia. It was not possible to demonstrate a consistent relationship between hospital cleanliness, as measured by weighted Patient Environment Action Team (PEAT) scores, and the incidence of MRSA bacteraemia. The large sizes of the data sets make it unlikely that a true correlation was missed. While a high standard of hospital cleanliness is a worthwhile goal, it is not helpful to repeatedly link MRSA control measures with improvements in standards of environmental cleanliness.

Bacteremia↗
PubMed2005

Blood DHEAS concentrations correlate with cognitive function in chronic schizophrenia patients: a pilot study.

There is evidence that neurosteroids such as DHEA and its sulfated form DHEAS can modulate cognitive function. We hypothesize that DHEA/S concentrations may be linked to cognitive impairment in schizophrenia. The aim of this pilot study was to test this hypothesis by examining the relationship between blood levels of DHEAS and cognitive function. The performance of 26 stable medicated chronic schizophrenia patients in a range of neuropsychological domains including verbal memory (Wechsler Memory Scale), executive function (AIM), memory of faces (PFMT), memory for objects (VOLT) and identification of facial emotional expressions (PEAT) was assessed. Single morning blood samples were assayed for levels of DHEAS and cortisol. Significant associations were found between DHEAS levels and DHEAS/Cortisol ratio and verbal memory, executive function and memory for faces. The relationship was independent of the age related reduction in DHEAS levels. These preliminary results suggest that DHEAS may be associated with cognitive impairment in schizophrenia.

Adult↗
PubMed2004

Organic matter transformation in the environment investigated by quantitative electron paramagnetic resonance (EPR) spectroscopy: studies on lignins.

The lignins separated from angiosperm and gymnosperm trees, peat and xylitic brown coal were investigated by quantitative EPR. Observed free radicals in lignins are sensitive to alkaline environment. Gaseous ammonia interacting with solid lignins in resonance cavity shifts quinone-hydroquinone equilibria towards formation of semiquinone anions. Complexation of copper(II) by lignins causes drastic decrease of the semiquinones in the matrices. Formation of lignin-Pb(II) complexes yielded radicals characterised by unusually low g-value (1.9999-2.0003). Monomeric structural units of the investigated lignins were recognised by pyrolysis with in situ methylation by tetramethylammonium hydroxide. Although for the natural lignins the mixture of normal semiquinone signals at g about 2.0034 and signals at g 1.9999 were observed, some monomeric components of lignins (e.g., caffeic acid, pyrogallol) gave pure lines at g = 1.9999. The bacterial oxidative biodegradation of lignin monomeric components and their Pb(II) complexes resulted in increase of the radical signals.

Bacillus subtilis↗
PubMed2004

A comparison of lead isotope ratios in the bark pockets and annual rings of two beech trees collected in Derbyshire and South Yorkshire, UK.

ICP-MS analysis of the bark pockets and annual rings of two beech (Fagus sylvatica L.) trees collected from Longshaw, Derbyshire and Swinton, South Yorkshire in the UK recorded differences in the (206)Pb/(207)Pb isotope ratio. In the Longshaw sample, the (206)Pb/(207)Pb isotope ratio of the bark pockets ( approximately 1914-1998, 78-260 microg g(-1) Pb) declined from approximately 1.16 to 1.12, whilst the annual rings (1899-1998, 0.2-2.5 microg g(-1) Pb) had a (206)Pb/(207)Pb ratio of approximately 1.18. In the Swinton sample, the bark pockets (approximately 1919-1998, 7-78 microg g(-1) Pb) declined from 1.15 to 1.11 and the annual rings (1899-1998, 0.2-0.5 microg g(-1) Pb) from 1.18 to 1.15. The data implied that the bark pockets accumulated lead directly from the atmosphere through wet and dry deposition, whilst the annual rings accumulated lead from the soil via the roots. The bark pockets recorded a relative decline in the accumulation of lead from indigenous sources, such as lead smelting and coal combustion (1.17-1.19), and increase in imported sources such as the smelting of Australian ores (1.04) and leaded petrol usage (1.06-1.09). In contrast, the annual rings at Longshaw recorded ratios typical of indigenous lead, whilst the annual rings in Swinton recorded a relatively small decrease in (206)Pb/(207)Pb reflecting leaded petrol usage. The decline in (206)Pb/(207)Pb of the bark pockets was consistent with the historical decline in (206)Pb/(207)Pb of atmospheric lead recorded in peat, lake sediments and archival herbage at other UK locations.

Environmental Monitoring↗
PubMed2004

Washout of accumulated testosterone in a watershed.

Testosterone is constantly excreted into the environment by both human and animal sources but little is known about how it is transported in the environment. In this study, testosterone was measured in 15 sites in the Upper Jordan Valley after major rain events (238 samplings) for two consecutive rain seasons. The area consists of small farms, cattle pasture, fish ponds with some urban development. One liter samples were extracted on solid phase columns and the eluates measured using specific radio-immunoassay for testosterone and estrogen (estradiol + estrone). The first rain season was the first above average season after a 3-year period of well below average rainfall. It was found in the rain season of 2001/2002, that following a rain sequence of 131 mm/week there was an initial large increase in the concentration of testosterone (maximum 6 ng/l) accompanied by high estrogen (maximum 6 ng/l), which then gradually declined to non-detectable levels (< 0.3 ng/l) over a period of 3 months. These peaks originated from runoff from cattle pasture and fish pond effluent. Later peaks consisted only of testosterone that was moderately associated with sulfate (r2 = 0.53, P < 0.05) and somewhat associated with total phosphorus (r2 = 0.49, P < 0.1) indicating that the origin was leaching from the sulfurous peat soil. In the following rainy season, which had recorded rainfalls, no testosterone peaks above 1 ng/l were seen. We conclude that the testosterone accumulated in the Upper Jordan Valley was washed out in two stages, first as surface runoff from cattle pasture and then as discharge from the soil.

Animals↗
PubMed2004

Characterization of dissolved organic matter from source to sea using fluorescence and absorbance spectroscopy.

Dissolved organic matter fluorescence, absorbance and dissolved organic carbon were measured from source to sea in the River Tyne catchment, of approximately 2935 km(2) and encompassing areas of contrasting land use. The catchment has three major tributaries: the North Tyne which has good water quality, high dissolved organic carbon concentrations and visible water colour from the high proportion of peat in its upper catchment; the South Tyne which has good water quality with typical riverine dissolved organic carbon concentrations and drains from limestone uplands; and the Derwent, a more urbanized catchment which is increasingly impacted by treated sewage effluent discharges towards its mouth. Thirty sample sites, 23 along the three main tributaries and seven within the estuary, were sampled on six occasions over the period 2002-2003. High absorbance at 340 nm and dissolved organic carbon concentration identify N Tyne waters due to the peaty headwaters, but no downstream trends in these parameters are observed in any of the tributaries, in contrast to the estuary where a rapid decrease is observed in both. Fluorescence in contrast demonstrated downstream trends in both intensity and wavelength, especially in the Derwent as it is increasingly impacted by anthropogenic dissolved organic matter. Elevated protein-like fluorescence intensity also fingerprints sewage effluent within the estuary. The absorbance coefficient at 340 nm was found to have the strongest correlation to dissolved organic carbon concentration, greater than all fluorescence intensity parameters measured. However, fluorescence analysis permits the source of the dissolved organic matter to be determined, and therefore has implications for understanding its fate in estuaries and the ocean.

Journal Article↗
PubMed2004

Potential biogeochemical and ecological development of a flooded tailings impoundment at the Kristineberg Zn-Cu mine, northern Sweden.

The potential short-term ( 10(2) years) biogeochemical and ecological effects of diverting stream water (pH 4.9-6.7) into a limed, flooded tailings impoundment (pH 8-12) were studied by combining geochemical and biological data. In the long-term perspective, the successional development of lakes was used as a natural analogue. Based on the vertical distribution of temperature and total dissolved solids (TDS < 0.22 microm), the impoundment can be characterised as a continuous/discontinuous cold polymictic lake, with holomictic summer circulation. A re-inoculation study indicated that the growth of autotrophic, aerobic bacteria (presumably Acidithiobacillus ferrooxidans) presently is inhibited by the high pH in the impoundment. In a short-term perspective, termination of liming and diversion of stream water into the impoundment will result in a complex interplay between physical, biogeochemical and ecological effects. A reduced vertical mixing of the approximately 2-m-deep water column, dissolution of calcite and gypsum (compounds of a sludge formed in the impoundment) and an enhanced microbiological activity are major expected effects. The dissolution of calcite may act as a pH buffer and result in metal remobilisation from the sludge. Excluding autochthonous organic matter produced in the impoundment, streamwater input of suspended matter and formation of settling flocculants are expected to result in a sediment accumulation rate of approximately 1.5 mg cm(-2) year(-1) (1.6-3.3 cm/10(2) years). Settling allochthonous organic C (0.15-0.30 mg C cm(-2) year(-1)) may serve as an oxygen barrier and as a reservoir of organic compounds capable of driving redox reactions. In a long-term perspective, a hydroseral development into a wetland/peatland can be expected, with a bog lake, poor fen or flat bog as final stage. This development presupposes a decreasing pH when liming is terminated and stream water is diverted into the impoundment. It also assumes that the impoundment will be similar to an acidified lake, and that the succession is driven by Sphagnum colonizing the impoundment. If the hydrological conditions/water level is affected (e.g., by climatic changes or a dam failure), a terrestrialization culminating in coniferous forest on peat soil may occur.

Acidithiobacillus↗
PubMed2005

Arsenic speciation and mobilization in CCA-contaminated soils: influence of organic matter content.

A laboratory incubation experiment was conducted to investigate the influence of organic matter content on arsenic speciation and mobilization in chromated copper arsenate (CCA)-contaminated soils. The study was performed with four synthetic CCA-contaminated soils, with a range of organic matter content (mixture of peat moss and poultry manure) varying between 0.5% and 15% (w/w), under unsaturated and aerobic conditions for 40 days. Changes in water-soluble arsenic speciation (As(V), As(III), MMAA, DMAA) were monitored over time in soil extracts by HPLC-ICP-MS and in the soil solid phase (As(III), As(V)) by a solvent extraction method. Irrespective of organic matter content, As(V) was the predominant soil bound and aqueous phase arsenic species. However, over 40 days, a high soil organic matter content (7.5% and 15%) was able to entail formation of soil bound As(III). Moreover, total water-soluble arsenic was positively correlated with dissolved organic carbon (r(2)=0.88). However, the organic matter content did not influence arsenic speciation in the soluble fraction; neither As(V) reduction nor arsenic biomethylation occurred within 40 days. An increase in dissolved organic carbon content promoted both As(V) and As(III) solubilization in soils. Also, over time, organic matter contents of 7.5% and 15% entailed the persistence of soluble As(V), likely due to the high content of dissolved organic compounds which prevented its sorption onto soil. Based on this data, the environmental risk of aerobic CCA-contaminated soils rich in organic matter may be due to an enhanced availability of soluble As(V) over time, rather than to the formation of the more toxic and more mobile As(III).

Arsenates↗