Elevated Concentrations Of Manganese Research Articles

CYTOGENETIC EFFECT MARKERS IN MOTHERS AND FETUSES EXPOSED TO ENVIRONMENTAL CHEMICAL MUTAGENS

Background and Aims: Maternal exposure to environmental chemical mutagens (heavy metals, formaldehyde) may enhance risk for congenital malformations and chromosome aberrations in fetuses (newborns). We aimed to determine cytogenetic effect markers in mothers and fetuses exposed to environmental chemical mutagens using epidemiological study data. Methods: A cytogenetic examination of 95 mother-newborn pairs exposed to environmental chemical mutagens including manganese, nickel, lead, formaldehyde (a study group), and 70 non-exposed dyads (a control group) was carried out analyzing metaphase chromosomes from mother and newborn’s blood lymphocytes by the standard method. Blood chemical mutagen concentrations were determined applying atomic absorption spectrophotometry, liquid chromatography. The relationship between the frequency of chromosome aberrations, and the exposure to the chemical mutagens was assessed using epidemiological study data and calculating odds ratio (OR). Results: The blood samples from the pregnant and parturient women were found to contain elevated formaldehyde, manganese, nickel, lead concentrations (1.5-12 fold increase compared to the reference levels) (p=0.001). Polymorphic chromosome changes were detected in 30% of the study group women that exceeded the control group indices by 5-fold. The probability (OR) of chromosome aberrations in newborns from the exposed women with chromosome polymorphism was higher (OR=6.7) compared to the control group. We determined the probability of chromosome aberrations in newborns whose mothers demonstrated high frequency of chromosome polymorphism associated with the exposure to formaldehyde and nickel (OR=10.5, p=0.001). The probability of numerous congenital malformations and chromosome aberrations was higher in newborns of women exposed to manganese, lead and nickel having an increased frequency of chromosome polymorphism (OR=2.7, p=0.001). Conclusions: Exposure markers are elevated concentrations of manganese, formaldehyde, nickel, lead in the mothers and newborns’ blood. Cytogenetic effect markers are high frequency of chromosome polymorphism in the mothers and associated chromosome aberrations in the newborns.

Analysis of bacterial diversity and metals in produced water, seawater and sediments from an offshore oil and gas production platform

Produced water is one of the largest waste products routinely discharged into the ocean from offshore oil and gas platforms. This study analyzed bacterial communities and metals in the produced water, surrounding seawater, and sediment around the Thebaud platform. The bacterial community within the produced water was different from the seawater (SAB=13.3), but the discharge had no detectable effect on the bacterial communities in the seawater (SAB>97). In contrast, genomic analysis of sediments revealed that the bacterial community from 250m was different (SAB=70) from other locations further from the discharge, suggesting that the produced water had a detectable effect on the bacterial community in the sediment closest to the discharge. These near-field sediments contained elevated concentrations of manganese and iron that are associated with the produced water effluent. The results suggested that the discharge of produced water has influenced the bacterial community structure of sediments adjacent to the platform.

Alfalfa Responses to Combined Use of Lime and Limiting Nutrients on an Acidic Soil

An on-farm field experiment was conducted on an acidic soil to investigate the effects of combined use of lime and deficient nutrients on herbage yield of alfalfa (Medicago sativa L.). Omitting lime and limiting nutrients led to elevated concentrations of aluminium (Al), iron (Fe), and manganese (Mn) in alfalfa leaves and stems and caused severe reductions in herbage yield of alfalfa. Combined use of lime (2 t ha−1) and nutrients [phosphorus (P): 20 kg ha−1, sulfur (S): 20 kg ha−1, zinc (Zn): 4 kg ha−1, and boron (B): 2 kg ha−1] had the maximum increase in groundcover, root biomass, nodulation, leaf retention, leaf-to-stem ratio, herbage yield, crude protein, and nutrient composition of alfalfa. These beneficial effects were due to raised soil pH; improved calcium (Ca), P, S, Zn, and B nutrition; and reduced Al, Mn, and Fe toxicity. Aluminium and all the nutrients except copper (Cu) were more concentrated in alfalfa leaves than stems. Aluminum concentration was about three times greater in the lower leaves than in upper leaves. Lower leaves also had much greater concentrations of Ca, Mg, K, S, Fe, Mn, Cu, and B compared with upper leaves. In contrast, P and Zn concentrations were greater in the upper leaves than in lower leaves. Results suggest that the combined use of lime and all the limiting nutrients may realize potential beneficial effects of alfalfa on acidic soils where more than one essential nutrient is deficient. This may increase growth potential, nitrogen contributions, and groundcover by alfalfa and reduce soil erosion and runoff.

Model Based Raw Water Quality Management – Manganese Mobilization Induced by Bank Filtration

AbstractIn many countries bank filtration is used as the first step of drinking water treatment. River water percolates the riverbed and aquifer sediments which serve as a natural filter removing substances like nitrate, particular and dissolved organic matter and trace elements. Raw water quality, therefore, depends on both river water quality as well as hydrogeochemical processes within the sediment. Exemplified by the case study of Auf dem Grind, Well II (Düsseldorf, Germany), the geohydraulic and hydrogeochemical processes of a catchment area that is strongly influenced by bank filtration were investigated. Raw water extracted from Well II showed significantly elevated manganese concentrations compared to river water and to raw water from other wells in the catchment area. A reactive transport model was developed for retracing the measured raw water quality. Retrospective modeling revealed the principles of long and midterm changes in raw water quality, especially fluctuations in manganese concentrations. Based on the model‐scenario, the effects of varying river water qualities and/or agricultural fertilization practices can be predicted. The quantitative understanding of coupled hydrogeochemical and hydraulic processes enables the development of sustainable strategies optimizing raw water quality, e. g. with regard to a cost effective water treatment.

English

In 1929, the Block P Mill and Tailings Site (Block P) near Monarch, MT was the largest lead producer in Montana. When the mill finally closed in 1943 the site left behind a legacy of barren, phytotoxic soil and an ongoing transport of hazardous trace elements into nearby streams. Problems included areas of soil acidity as low as 1.8 pH, and zones with highly elevated concentrations of arsenic, cadmium, copper, lead, zinc and manganese in both soils and tailings materials. As a result, much of Block P, which would have been fully covered with vegetation if undisturbed, was nearly devoid of plant life. In 2001, however, it was decided to clean up and restore Block P to a functional site with natural vegetation. In 2004 and 2005, waste materials were consolidated to a centralized repository. Then, soil amendments (compost, slow-release fertilizer and lime) were added to areas from which tailings were removed, leave-area soils and imported fill materials. In 2005 and 2006, the project site was replanted with native grass and forb seeds, as well as containerized woody plant species that had been propagated from local stock. In July 2008, scientists from ESG monitored the status of revegetation at Block P. Monitoring included assessments of containerized woody plant survival, herbaceous cover, and overall cover on the nine revegetation units at the site. The monitoring results show a continued trend toward successful revegetation. The average containerized woody plant survival, weighted for unit size, was 74 percent, which exceeds the 70 percent project goal. Average herbaceous canopy cover and average total canopy cover of all plants across the entire project site are respectively 46 and 49 percent. The canopy cover of native species far exceeds non-native canopy cover, the cover of weedy exotic species is minimal, and hundreds of woody volunteer plants are appearing. The improvements in vegetation, environmental, and aesthetic values of the Block P Mill and Tailings site are clear and palpable, and demonstrate the efficacy of using appropriate soil amendments and site-adapted native plant species to restore even the most challenging of disturbed sites.

English

In August 2008, a rotating cylinder treatment system (RCTS TM ) demonstration was conducted near Gladstone, CO. The RCTS TM is a novel technology developed to replace the aeration/oxidation and mixing components of a conventional lime precipitation treatment system for mining influenced water (MIW). The RCTS TM realizes several operational benefits, including enhanced lime utilization by the treatment system, reduced maintenance requirements, and reduced power consumption by the aeration/mixing components of the treatment process. Gladstone is located in the upper Animas River watershed, near Silverton, CO, at an elevation of about 10,500 ft. Approximately 1,500 abandoned mine sites exist in the region. Cement Creek, a tributary to the Animas River, is characterized by elevated metals concentrations and has a typical pH of 3.3. Aluminum, cadmium, copper, iron, manganese, and zinc are the primary mining-related contaminants of concern for Cement Creek. The American Tunnel drainage is a significant source of MIW entering Cement Creek, characterized as a reduced water with elevated concentrations of aluminum, cadmium, copper, iron, manganese, and zinc, and acidic pH. During the two-week demonstration, the RCTS TM treated surface water from Cement Creek and MIW discharged from the American Tunnel. The RCTS TM was operated at flow rates ranging from 30 to 400 gallons per minute during this demonstration. Monitoring activities included logging field parameters including lime consumption, pH, temperature, dissolved oxygen, and oxidation-reduction potential, and collection of 50 samples for laboratory analysis. This paper presents the results of the RCTS TM demonstration, with an emphasis on evaluating RCTS TM effluent water quality, and comparing the RCTS TM lime consumption to conventional MIW treatment systems.

Survey and assessment of post volcanic activities of a young caldera lake, Lake Cuicocha, Ecuador

Abstract. Cuicocha is a young volcano adjacent to the inactive Pleistocene Cotacachi volcano complex, located in the western cordilleras of the Ecuadorian Andes. A series of eruptions with intensive ash emission and collapse of the caldera occurred around 4500–3000 y BP. A crater 3.2 km in diameter and a maximum depth of 450 m was formed. Further eruptions of the volcano occurred 1300 y BP and formed four smaller domes within the caldera. Over the last few hundred years, a caldera lake has developed, with a maximum depth of 148 m. The lake water is characterized by sodium carbonate with elevated concentrations of manganese, calcium and chloride. Nowadays, an emission of gases, mainly CO2, and an input of warm spring water occur in Lake Cuicocha. The zone of high activity is in the western basin of the lake at a depth of 78 m, and continuous gas emissions with sediment resuspension were observed using sonar. In the hypolimnion of the lake, CO2 accumulation occurs up to 0.2% saturation, but the risk of a limnic eruption can be excluded at present. The lake possesses monomictic stratification behaviour, and during overturn an intensive gas exchange with the atmosphere occurs. Investigations concerning the sedimentation processes of the lake suggest only a thin sediment layer of up to 10–20 cm in the deeper lake basin; in the western bay, in the area of gas emissions, the lake bottom is partly depleted of sediment in the form of holes, and no lake colmation exists. Decreases in the lake water level of about 30 cm y−1 indicate a percolation of water into fractures and fissures of the volcano, triggered by a nearby earthquake in 1987.

Maternal and Early Life Exposure to Manganese in Rural Bangladesh

Manganese exposure and biomarker concentrations during early pregnancy and lactation were investigated in 408 women living in an area with elevated concentrations of both arsenic and manganese in drinking water derived from wells. About 40% of the water samples had manganese concentrations above the World Health Organization's guideline value and showed a strong inverse correlation with arsenic concentrations. Water manganese was found to correlate to urine concentrations, but not to blood or breast milk concentrations. No correlations were found among manganese concentrations in urine, blood, or breast milk. Compared to other populations, manganese concentrations in both urine and blood, but not breast milk, were elevated in the Bangladeshi women and more similar to those of occupationally exposed groups. The lack of associations with water manganese is likely due to variable exposure via water and food, and differences in bioavailability, as well as a complex and/or strict regulation of intestinal manganese absorption, in turn being influenced by nutritional as well as physiological and genetic factors. The results indicate that elevated maternal manganese exposure does not necessarily lead to exposure of breast-fed infants, stressing the importance of breast feeding in high manganese areas. However, the implications of fetal exposurefrom elevated maternal exposure need further investigation.

Elevated Serum Concentrations of Cobalt, Chromium, Nickel, and Manganese After Metal-On-Metal Alloarthroplasty of the Hip: A Prospective Randomized Study

In this prospective randomized study, we investigate metal ion concentrations and clinical outcome 2 years after metal-on-metal (28 patients) or metal-on-polyethylene (26 patients) hip arthroplasty with 28-mm modular heads. Metal ion concentrations in patient serum were analyzed by high-resolution plasma mass spectrometry. The clinical outcome was almost identical in both groups with respect to the Harris hip score and the Medical Outcome Study Short Form–36; and on plain radiography, no signs of loosening occurred in any group. In the metal-on-metal group, concentrations of all investigated ions increased significantly when compared with preoperative values: cobalt, 15.3-fold (95% confidence interval [CI], 9.4-21.2); chromium, 5.2-fold (CI, 3.5-7.0); nickel, 2.1-fold (CI, 1.2-3.0); and manganese, 1.6-fold (CI, 1.3-2.0). In the metal-on-polyethylene group, a smaller but significant increase in the concentrations of cobalt and nickel occurred, whereas concentrations of the other ions did not change significantly.

Contamination of groundwater and risk assessment for arsenic exposure in Ha Nam province, Vietnam

The characteristics of arsenic-contaminated groundwater and the potential risks from the groundwater were investigated. Arsenic contamination in groundwater was found in four villages (Vinh Tru, Bo De, Hoa Hau, Nhan Dao) in Ha Nam province in northern Vietnam. Since the groundwater had been used as one of the main drinking water sources in these regions, groundwater and hair samples were collected in the villages. The concentrations of arsenic in the three villages (Vinh Tru, Bo De, Hoa Hau) significantly exceeded the Vietnamese drinking water standard for arsenic (10 µg/L) with average concentrations of 348, 211, and 325 μg/L, respectively. According to the results of the arsenic speciation testing, the predominant arsenic species in the groundwater existed as arsenite [As(III)]. Elevated concentrations of iron, manganese, and ammonium were also found in the groundwater. Although more than 90% of the arsenic was removed by sand filtration systems used in this region, arsenic concentrations of most treated groundwater were still higher than the drinking water standard. A significant positive correlation was found between the arsenic concentrations in the treated groundwater and in female human hair. The risk assessment for arsenic through drinking water pathways shows both potential chronic and carcinogenic risks to the local community. More than 40% of the people consuming treated groundwater are at chronic risk for arsenic exposure.

Parkinsonism in patient with hepatitis C

T1-weighted MRI of the brain revealed hyperintensity in the basal ganglia, a finding characteristic of hepatic encephalopathy. Therapy with L-ornithine-L-aspartate (5 g, three times daily) was initiated along with antibiotic treatment, which resulted in resolution of the parkinsonian symptoms and improvement in cognition. On review visit at one month, MMSE was 29/30, clock drawing was unchanged, and there was a significant reduction in parkinsonism symptoms (Fig. 3). Hyperintensities in the basal ganglia on T1-weighted brain MRI sequences have been reported in the majority of cirrhosis patients. Elevated serum manganese concentrations are considered responsible for these hyperintensities of the globus pallidus, with manganese interfering with dopamine metabolism, thus causing parkinsonian features in up to 89% of patients with cirrhosis. Although the exact mechanism of the disorder is unknown, ammonia plays a crucial role, supported by the finding that the administration of L-ornithine-L-aspartate significantly reduced serum ammonia and neurological symptomatology. Although parkinsonism is an idiopathic disorder in most cases, secondary forms of the disease should be sought, particularly if the patient’s history points to some of the known causes. The case presented also illustrates the importance of brain MRI in selected patients with newonset parkinsonism.

Characterisation of an attenuation system for the remediation of Mn(II) contaminated waters

Soluble manganese (Mn(II)) can be problematic in surface, ground waters and in domestic water supplies. Many mine drainage waters contain highly elevated concentrations of manganese (often > 100 mg l − 1 ). Current systems for remediating mine waters, although effective for other metals, are often inefficient at removing manganese. This paper describes the development of self-sustaining, low-cost bioreactors that can be used in situ for passive removal of manganese from contaminated water courses of pH > 4. A prototype bioreactor, set-up using Mn(IV)-coated pebbles from a fresh-water stream, was tested over one year and shown to be effective in removing Mn(II) from 10 to < 0.25 mg l − 1 . Managanese-oxidising microorganisms isolated from the bioreactor included two species of fungi and one bacterial species. The fungi were identified as belonging to the order Pleosporales (Ascomycetes), and one was related (98% 18S rRNA gene sequence identity) to a known Mn(II)-oxidising fungus. The bacterial isolate was closely related to the α-proteobacterium Bosea thiooxidans. T-RFLP analysis showed that one or both of the fungal isolates were the dominant eukaryotes in the bioreactor community, while the Bosea isolate did not appear to be numerically important in the bacterial community.

Arsenic removal from groundwaters containing iron, ammonium, manganese and phosphate: A case study from a treatment unit in northern Greece

The city of Malgara in the municipality of Aksios, in northern Greece, relies on local groundwater for the municipal water supply. The groundwater has pH 7.9 and contains elevated concentrations of arsenic (20 µg/L), phosphate (550 µg/L), manganese (235 µg/L) and ammonium (1.2 mg/L), whereas the iron concentration (165 µg/L) is relatively low. Arsenic, manganese and ammonium exceed the parametric values, according to the EC directive 98/83. This directive has been adopted as national law since the beginning of 2003 and a groundwater treatment plant is in operation since the beginning of 2005. The treatment plant consists of aeration, up-flow filtration for the biological oxidation of ammonium, manganese and arsenic, followed by coagulation with FeClSO 4 at a concentration of 2.3 mg Fe/L, and final down-flow filtration for the removal of arsenic and the additional iron. In a final stage, the water is disinfected with NaOCl before the distribution to the consumers. During aeration, Fe(II) is oxidized and some phosphate is sorbed on the formed iron oxides but remains in suspension until it is removed during the subsequent biological filtration stage. Mn(II) is oxidized by biological oxidation and the produced insoluble manganese oxides are removed by filtration. NH 4 + is biologically oxidized and removed from the water via nitrification and formation of nitrates. As(III) is oxidized but not removed during the biological filtration stage. Arsenic is removed to below 10 µg/L during the subsequent coagulation and filtration treatment stage. Similarly, the final concentrations of Fe(tot), Mn(tot) and NH 4 + are below the EC parametric values of 200, 50 and 500 µg/L respectively.

IMPACTS OF ESTUARINE ACIDIFICATION ON SURVIVAL AND GROWTH OF SYDNEY ROCK OYSTERS SACCOSTREA GLOMERATA (GOULD 1850)

Estuarine acidification caused by outflows from acid sulfate soils (ASS), impacts many estuaries in eastern Australia. Affected waters are characterized by low pH and elevated concentrations of metals, particularly iron, aluminum, and manganese. The effects of low pH and elevated metals, associated with ASS-affected water, on adult Sydney rock oysters Saccostrea glomerata have not been previously studied in detail. Most production of Sydney rock oysters occurs in estuaries along the Australian east coast and has significantly decreased over the last 30 y. To investigate poor oyster production in particular areas of the Manning River, New South Wales, Australia, associations between ASS drainage water, estuarine acidification, and Sydney rock oyster survival and growth were studied. This involved a seven-month field study where water quality and oyster survival and growth was measured at seven sites differentially impacted by ASS-affected waters. Estuarine acidification on the Manning River followed periods of heavy rainfall and caused widely fluctuating pH levels, combined with low electrical conductivities and high concentrations of iron and aluminum at experimental sites selected to expose Sydney rock oysters to ASS-affected waters. Hydrologic characteristics and location of experimental sites controlled the extent of impact caused by ASS-affected waters. Sites exposed to ASS-affected waters had a significantly higher (P < 0.001) level of oyster mortality. Mortalities in small oysters were significantly higher (P < 0.05) than mortalities in large oysters. This was attributed to acid-induced shell degradation, which eventually caused perforation of the thinner shells of small oysters. Mortalities of small oysters increased after 42 days of exposure. ASS-affected waters also significantly reduced large and small oyster growth (P < 0.001). Growth of oysters improved and mortalities stabilized at sites impacted by ASS-affected waters in dryer periods because of the improvement in water quality.

Cobalt and manganese stress in the microalga Pavlova viridis (Prymnesiophyceae): Effects on lipid peroxidation and antioxidant enzymes

Pollution of marine environment has become an issue of major concern in recent years. Serious environmental pollution by heavy metals results from their increasing utilization in industrial processes and because most heavy metals are transported into the marine environment and accumulated without decomposition. The aim of the present study is to investigate the effects on growth, pigments, lipid peroxidation, and some antioxidant enzyme activities of marine microalga Pavlova viridis, in response to elevated concentrations of cobalt (Co) and manganese (Mn), especially with regard to the involvement of antioxidative defences against heavy metal-induced oxidative stress. In response to Co 2+, lipid peroxidation was enhanced compared to the control, as an indication of the oxidative damage caused by metal concentration assayed in the microalgal cells but not Mn 2+. Exposure of Pavlova viridis to the two metals caused changes in enzyme activities in a different manner, depending on the metal assayed: after Co 2+ treatments, total superoxide dismutase (SOD) activity was irregular, although it was not significantly affected by Mn 2+ exposure. Co 2+ and Mn 2+ stimulated the activities of catalase (CAT) and glutathione (GSH), whereas, glutathione peroxidase (GPX) showed a remarkable increase in activity in response to Co 2+ treatments and decreased gradually with Mn 2+ concentration, up to 50 μmol/L, and then rose very rapidly, reaching to about 38.98% at 200 μmol/L Mn 2+. These results suggest that an activation of some antioxidant enzymes was enhanced, to counteract the oxidative stress induced by the two metals at higher concentration.

The Conformations of the Manganese Transport Regulator of Bacillus subtilis in its Metal-free State

The manganese transport regulator (MntR) from Bacillus subtilis binds cognate DNA sequences in response to elevated manganese concentrations. MntR functions as a homodimer that binds two manganese ions per subunit. Metal binding takes place at the interface of the two domains that comprise each MntR subunit: an N-terminal DNA-binding domain and a C-terminal dimerization domain. In order to elucidate the link between metal binding and activation, a crystallographic study of MntR in its metal-free state has been undertaken. Here we describe the structures of the native protein and a selenomethionine-containing variant, solved to 2.8 Å. The two structures contain five crystallographically unique subunits of MntR, providing diverse views of the metal-free protein. In apo-MntR, as in the manganese complex, the dimer is formed by dyad-related C-terminal domains that provide a conserved structural core. Similarly, each DNA-binding domain largely retains the folded conformation found in metal bound forms of MntR. However, compared to metal-activated MntR, the DNA-binding domains move substantially with respect to the dimer interface in apo-MntR. Overlays of multiple apo-MntR structures indicate that there is a greater range of positioning allowed between N and C-terminal domains in the metal-free state and that the DNA-binding domains of the dimer are farther apart than in the activated complex. To further investigate the conformation of the DNA-binding domain of apo-MntR, a site-directed spin labeling experiment was performed on a mutant of MntR containing cysteine at residue 6. Consistent with the crystallographic results, EPR spectra of the spin-labeled mutant indicate that tertiary structure is conserved in the presence or absence of bound metals, though slightly greater flexibility is present in inactive forms of MntR.

Arsenic and Other Metal Contamination of Groundwaters in the Industrial Area of Thessaloniki, Northern Greece

In groundwater, used for drinking water supply in the greater industrial area of Thessaloniki, in Northern Greece, concentrations of total arsenic exceeded the WHO provisional guideline value and the EU maximum contaminant level (MCL) of 10 microg/L. The concentration of total arsenic was in the range between 4-130 microg/L, whereas the median value was 36 microg/L and the average concentration 46 microg/L. Nine out of the eleven wells contained total arsenic at concentration higher than 10 microg/L and it should be stressed that 6 of them contain arsenic at concentrations between 10 (new MCL) and 50 microg/L (previous MCL). The examined groundwaters were found to contain elevated concentrations of manganese and phosphate. Arsenic had a positive correlation with the pH, indicating the possible effect of pH on arsenic mobilisation. These findings emerge the problem of contamination from arsenic, since, according to the EU directive 98/83, all drinking water sources within the European Union should have achieved compliance with the new limits by 12/2003, implying that the situation requires urgent remedial action.

Blending membrane treated WTP waste residuals with finished water: impacts to water quality and biofilm formation

The purpose of this study was to evaluate the impact of blending filtered water with treated waste residuals streams from a water treatment plant on finished water quality and biofilm formation in a modelled distribution system. A mixed waste residual stream composed of an equalized blend of filter backwash water (FBWW) and clarifier sludge blowdown was treated with a pilot-scale ultrafiltration (UF) membrane. The UF treated residuals stream was blended with plant finished water to model a recycle return location to the clearwell of a drinking water treatment train. Field evaluations involved the use of bench-scale annular reactors (ARs) to investigate two parallel model distribution systems: (i) a control system representing 100% plant filtered water (AR-filtered) and (ii) a blended system representing 10% by volume of the UF permeate blended with plant filtered water (AR-blended). To evaluate the impact of chemical disinfection on bacterial regrowth and the fate of inorganic constituents, free chlorine, monochloramine and chlorine dioxide were fed to the ARs during three distinct disinfection trials. An initial disinfection trial consisted of a control run during which no disinfectant was added. The results of the field experiments showed that blending 10% by volume of the UF permeate with plant finished water did not significantly impact regrowth of heterotrophic bacteria in the bulk or biofilm phases. Throughout each disinfection trial, the largest difference in HPCs noted between the two systems was 1 log in the bulk and biofilm samples. Free chlorine and monochloramine disinfection resulted in the greatest mitigation of microbial biofilm in both AR-filter and AR-blended systems. Aluminum, manganese, and iron in the bulk phase were found to be below Canadian Drinking Water Guideline levels. However, the detection of manganese-oxidizing bacteria (MOB) and elevated manganese in biofilm samples from AR-blended could hold potential implications for blending UF treated residual streams on biofilm development and inorganic post-precipitation occurrences in systems treating source waters containing elevated concentrations of manganese.

Hole transport anomaly in high- TC ferromagnet (Zn,Mn)GeP 2

Anomalous Hall effect and a large negative magnetoresistance (up to −8.5%) have been found in the high- T C ferromagnetic chalcopyrite (Zn,Mn)GeP 2. The elevated manganese concentration in the top diffusion layer grown on ZnGeP 2 isolated substrate gives rise to the increased hole conductivity and the temperature dependence of electric resistance ρ( T) typical of a metallic trace which indicate the charge carrier degeneration in combination with ferromagnetism. Additionally, we found a hysteresis of magnetoresistance Δ ρ/ ρ 0 vs. H is associated with change in a magnetic order at low temperatures, T<50 K. The effect accompanies the reversal sign of Δ ρ/ ρ 0 and is consistent with a singularity of magnetization vs. temperature. These anomalies observed for the first time in the high- T C ferromagnetic chalcopyrites II–IV–V 2:Mn are explained by the phenomenological cluster model for ferromagnets.

Physical and chemical characterization of gas hydrates and associated methane plumes in the Congo–Angola Basin

As a part of the ZAIANGO IFREMER/TOTAL-FINA-ELF program, gas hydrates were collected from a gravity sediment core on the Congo–Angola margin during the ZAI-ROV cruise (December 2000). Gas hydrates, associated with a deep giant (800 m in diameter) active depression called “pockmark,” occurred from the sediment surface down to 12 m depth, at 3160 m water depth. Elevated concentrations of particles, manganese, iron, and methane detected in the water column close to the sediment surface reveal intense fluid circulation transporting methane-rich turbid fluids into the overlying bottom waters. Free gas is liberated via diffusion and/or advection and from destabilizing gas hydrates. The gas hydrates occur as small fragments and massive crystal aggregates, mostly disseminated irregularly in the highly disturbed sediment and escaping in the overlying deep seawater, creating methane-rich plumes. The dissociation of solid CH 4 hydrate particles rising in a turbulent flow may explain the high heterogeneity of methane concentration and CH 4 peaks measured in vertical profiles. Raman spectroscopy revealed that the gas hydrates recovered from the Congo–Angola are mainly 100% methane gas hydrate of structure I cubic with a lattice constant of a=12 A°, but H 2S and CO 2 are co-clathrated with CH 4 in cages. Analyses of hydrate water show depletions of Cl, SO 4, Na, Mg, Ca, and Sr, and enrichments of Si, Cs, and Ba, compared to the ambient deep seawater. Gas analysis shows that methane is the major component (99.1%), but CO 2 (0.83%) and heavier gases such as C 2H 6 (0.043%) and H 2S (0.02%) are also present as traces. Helium concentrations were in the range of 0.04–1.3 ppm, with slightly radiogenic 3He/ 4He ratios between 6.6×10 −7 and 7.6×10 −7. The hydrate methane has δ 13C of −69.3‰ (PDB) and δ D of −199‰ (V-SMOW), and the hydrate CO 2 has δ 13C of −17.5‰ (PDB). These values indicate a primarily microbial origin for the CH 4, which is generated through bacterial CO 2 reduction, as previously observed on many continental margins where solid gas hydrates were sampled.