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MOLYBDATE− Molybdenum accumulation in sediments: a quantitative indicator of hypoxic water conditions in Narragansett Bay, RI

Authigenic molybdenum Mo  accumulation in marine sediments has often been used as a qualitative indicator of hypoxic bottom water. To investigate its use as a quantitative indicator of hypoxic exposure, sediment cores were collected from water quality monitoring sites in Narragansett Bay RI, USA  that experience varying periods of hypoxia. Total Mo concentrations in surficial 0-1 cm  sediments were determined by total digestion and ICP-MS analysis. Lithogenic contributions to total Mo concentrations were estimated by multiplying measured concentrations of aluminum Al  by the mean crustal Mo:Al ratio and subtracting them from the total concentrations to yield the authigenic fraction. 210 Pb dating was used to determine sediment accumulation rates at each site. Mean annual periods of hypoxia in bottom waters were determined from continuous monitoring data for the years coinciding with the top 1 cm of sediment. Results indicated a linear relationship between authigenic Mo concentrations and frequency of hypoxia, although the relationships differed between different sampling periods. These results demonstrate the potential of sedimentary Mo as a tool for assessing the spatial and temporal extent of hypoxia in coastal waters.

W. S. Boothman, L. Coiro, and S. B. Moran,Molybdenum accumulation in sediments: a quantitative indicator of hypoxic water conditions in Narragansett Bay, RI, Estuar Coast Shelf Sci, 2022, 267, 1-10.



MOLYBDATE− Improving monitoring of fish health in the oil sands region using regularization techniques and water quality variables

Trout-perch are sampled from the Athabasca River in Alberta, Canada, as a sentinel species for environmental health. The performance of trout-perch populations is known to be influenced by the quality of the water in which they reside. Using climate, environmental, and water quality variables measured in the Athabasca River near trout-perch sampling locations is found to improve model fitting and the predictability of models for the adjusted body weight, adjusted gonad weight, and adjusted liver weight of trout-perch. Given a large number of covariables, three variable selection techniques: stepwise regression, the lasso, and the elastic net EN  are considered for selecting a subset of relevant variables. The models selected by the lasso and EN are found to outperform the models selected by stepwise regression in general, and little difference is observed between the models selected by the lasso and EN. Uranium, tungsten, tellurium, pH, molybdenum, and antimony are selected for at least one fish response.

P. G. McMillan, Z. Z. Feng, L. E. Deeth, and T. J. Arciszewski,Improving monitoring of fish health in the oil sands region using regularization techniques and water quality variables, Sci Total Environ, 2022, 811, 152301.


MOLYBDATE− Ecotoxicological risk ranking of 19 metals in the lower Yangtze River of China based on their threats to aquatic wildlife

With thousands of chemicals discharged into the aquatic environment, it is necessary to identify those that are likely to be having the greatest impact on wildlife to better protect the ecosystem. A risk ranking approach was developed to compare the ecotoxicological risk of chemicals on aquatic wildlife with a wide range of environmental measurement data and ecotoxicity data. Nineteen metals including some rarely monitored ones including antimony Sb , molybdenum Mo , cobalt Co , vanadium V , titanium Ti  and thallium Tl  in the lower Yangtze River were risk ranked as a case study. The risk ranking approach was conducted in three tiers: general risk ranking, lethal effects vs. non-lethal effects risk ranking, and species group-specific risk ranking. Iron, copper and titanium were identified as being of greatest concern. The contamination of iron, zinc, copper and nickel was widespread and may have already harmed wildlife according to the overlap between ecotoxicity and monitored levels. Based on this analysis, the risk from copper and some rarely monitored metals titanium and boron  may have been underestimated. Greater efforts to reduce copper, iron and titanium contamination could make an important difference to the health of Chinese freshwater organisms in the Yangtze River.

Y. Zhang, M. Zhang, W. Yu, J. Li, and D. Kong,Ecotoxicological risk ranking of 19 metals in the lower Yangtze River of China based on their threats to aquatic wildlife, Sci Total Environ, 2022, 812, 152370.

MoS2 Environmental implications of MoS2 nanosheets on rice and associated soil microbial communities

Molybdenum disulfide MoS2  is a transition metal dichalcogenides TMDCs  material that is seeing rapidly increasing use. The wide range of applications will result in significant environmental release. Here, the impact of MoS2 nanosheets on rice and associated soil microbial communities was evaluated. Rice plants were grown for 4 weeks in a natural paddy soil amended with either 1T or 2H phase MoS2 nanosheets at 10 and 100 mg kg-1 . The 1T MoS2 nanosheets have a significantly greater dissolution rate 58.9%  compared to 2H MoS2 4.4% , indicating the instability of 1T MoS2 in environment. High dissolution rate resulted in a high Mo bioaccumulation in rice leaves 272 and 189 mg kg-1  under 1T and 2H exposure at 100 mg kg-1  . However, this did not induce overt phytotoxicity, as indicated by a range of phenotypic or biochemical based determine endpoints, e.g., biomass, photosynthetic pigments, and malondialdehyde MDA  content. Additionally, rice P uptake was significantly increased upon exposure to 1T and 2H MoS2 10 mg kg-1  . Gas chromatography-mass spectrometry GC-MS  reveals that both phases of MoS2 in soil systematically enhanced the carbon and nitrogen related metabolic pathways in exposed plants. Soil 16S rRNA gene sequencing data show that soil microbial community structure was unchanged upon MoS2 exposure. However, both phases of MoS2 remarkably increased the relative abundance of N2-fixation cyanobacteria, and 2H MoS2 exposure increased a plant growth-promoting rhizobacteria-Bacillus. Overall, our results suggest that MoS2 nanosheets at tested doses did not exert negative impacts on rice plant and the associated soil microbial community.

L. Zhao, S. Chen, X. Tan, X. Yan, W. Zhang, Y. Huang, R. Ji, and J. C. White,Environmental implications of MoS2 nanosheets on rice and associated soil microbial communities, Chemosphere, 2022, 291, 133004.


Evaluating the uptake of ten heavy metals by kidney bean (phaseolus vulgaris l.) grown in a soil-sludge mixture using a regression model

Severe human health risks can be caused by consuming vegetables contaminated by heavy metals (HMs); thus, assessing the HM uptake by these plants is important The current work was performed to construct a regression model for predicting the concentration of ten HMs in four tissues of Phaseolus vulgaris (mots, stems, leaves and pods) based on their concentration in a soil-sludge mixture, soil organic matter (OM) and soil pH. For pods, the regression equation with the highest coefficient of determination (R-2 = 0.99) and model efficiency (ME = 1.00) but the lowest mean normalized bias (MNB = 0.01) was that of cobalt. For leaves, the equation with the highest R-2 (0.90) and ME (0.92) but the lowest MNB (0.001) was that of molybdenum. Comparable findings were obtained for molybdenum in the stems and manganese in the roots. All t values that assessed the difference between the actual and predicted values of the ten HMs in the four tissues were nonsignificant. Thus, these models could be used as a risk assessment tool for P. vulgaris cultivated in soil-sludge combinations.

E. M. Eid, K. H. Shaltout, S. A. M. Alamri, N. A. Sewelam, and T. M. Galal,EVALUATING THE UPTAKE OF TEN HEAVY METALS BY KIDNEY BEAN (PHASEOLUS VULGARIS L.) GROWN IN A SOIL-SLUDGE MIXTURE USING A REGRESSION MODEL, Applied Ecology and Environmental Research, 2020, 18, 7021-7039.


Effects of a century of mining and industrial production on metal contamination of a model saline ecosystem, Great Salt Lake, Utah

Effects of mining and metals production have been reported in freshwater lake sediments from around the world but are rarely quantified in saline lake sediments, despite the importance of these lake ecosystems. Here we used dated sediment cores from Great Salt Lake, Utah, USA, a large saline lake adjacent to one of the world's largest copper mines, to measure historical changes in the deposition of 22 metals. Metal concentrations were low prior to the onset of mining in the catchment in 1860 CE. Concentrations of copper, lead, zinc, cadmium, mercury, and other metals began increasing in the late 1800s, with peaks in the 1950s, concomitant with enhanced mining and smelting activities. Sedimentary metal concentrations in the 1950s were 20-40-fold above background levels for copper, lead, silver, and molybdenum. Concentrations of most metals in surficial sediments have decreased 2-5-fold, reflecting: 1) storage and mineralization of sedimenting materials in a deep brine layer, thereby reducing metal transport to the sediments; 2) improved pollution control technologies, and; 3) reduction in mining activity beginning in the 1970s and 1980s. Despite reductions, concentrations of many metals in surficial sediments remain above acceptable contamination thresholds for aquatic ecosystems with migratory birds, and consumption advisories for mercury have been placed on three waterfowl species. The research also highlights that metal deposition in saline lakes is complicated by effects of hypersaline brines and deep-water anoxia in regulating sediment redox and release of metals to surface waters. Given the importance of saline lakes to migratory birds, metals contamination from mining and metals production should be a focus of saline lake remediation. (C) 2020 Elsevier Ltd. All rights reserved.

W. A. Wurtsbaugh, P. R. Leavitt, and K. A. Moser,Effects of a century of mining and industrial production on metal contamination of a model saline ecosystem, Great Salt Lake, Utah, Environmental Pollution, 2020, 266, 115072.


Molybdenum in the Atmosphere

Release of molybdenum into the environment can occur through weathering, agricultural uses of molybdenum compounds, and industrial processes. Molybdenum in air has a range of values. Molybdenum concentrations in air are higher in urban areas than in rural areas. The combustion of fossil fuels is a constant source of molybdenum [Parker, 1986]. Relatively high concentrations are present in air-borne ash expelled usually during the combustion of fossil fuels.

[US DHEW, 1966; Adler, 1957; Adkins and Losee, 1970; Allaway et al., 1968; Anderson, 1966; Anderson and Grensfelt, 1973.]
Parker, G. A., Molybdenum in: Hutzinger, O. (ed.), Handbook of Environmental Chemistry , 1986, 3D, 217. Springer-Verlag, Berlin.
US DHEW, Air Quality Data, National Air Sampling Network, 1966, Public Health Service.
Adler, P., Odont. Révy Suppl., 1957, 48.
Adkins, B. L. and Losee, F. L., N.Y. State dent. J., 1970, 36, 618.
Allaway, W. H., Kubota, J., Losee, F. L. and Roth, M., Arch. Environ. Health, 1968, 16, 342.
Anderson, R. J., Brit. dent. J., 1966, 120, 271.
Anderson, G. and Grensfelt, P., IVL, Gothenburg B, 1973, 138.


Particulate matter in lung fluid

Workplace exposure to particulate matter, bio-accessible, and non-soluble metal compounds during hot work processes

While exposure to air contaminants from metal arc welding at workplaces has been intensively investigated over the last five decades, other hot work processes, such as flame and plasma cutting, air carbon arc gouging, and surface grinding have not received as much attention. Exposures to particulate matter (PM) during selected hot work processes, such as metal active gas (MAG) and manual metal arc (MMA) welding, flame and plasma cutting, air carbon arc gouging, and surface grinding were measured. Respirable, inhalable, and "total" fractions of the PM were collected with different air samplers in the workers' breathing zone. Concentrations of PM, chromium (Cr), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), copper (Cu), and lead (Pb) were determined in the samples by using gravimetric analysis and plasma-based analytical atomic spectrometry techniques. Bio-accessibility of the elements was investigated by using a synthetic lung lining fluid (Hatch s solution) for the leaching of soluble metal compounds in the collected samples. Short term (15-75 min) workplace air concentrations of PM, Cr, Fe, Mn, Ni and Cu in the workers breathing zone during hot work processes were found to be high compared to the current 8-hr time-weighted average (TWA) exposure limit values (ELVs) in use in many countries. The short-term median concentrations of PM during the different hot work processes varied between 6.0 and 88.7 mg m(-3) and between 15.1 and 193 mg m(-3) in the respirable and inhalable fractions, respectively. The highest median concentration of Fe (107 mg m(-3)) and Mn (28.7 mg m(-3)) was found in the inhalable fraction during plasma cutting and air carbon arc gouging, respectively. More than 40% of the inhalable PM generated during flame and plasma cutting, air carbon arc gouging and surface grinding was present in the respirable fraction. There was large variation in the bio-accessibility of the elements in PM collected during the different hot work processes.

B. Berlinger, U. Skogen, C. Meijer, and Y. Thomassen,Workplace exposure to particulate matter, bio-accessible, and non-soluble metal compounds during hot work processes, Journal Of Occupational And Environmental Hygiene 2019, 16, 378–386.

See also B. Berlinger et al., A study of the bio-accessibility of welding fumes, J. Environ. Monit., 2008, 10, 1448–1453.

Molybdenum in the Atmosphere
Description of AreaSourceConcentration /microg/m3
Atmosphere [1]   <0 - 0.03
Industrial UK [2] Air borne ash 10 - 40
Industrial UK [3] Light heating oil 0.1
Industrial UK [3] Heavy heating oil 0.5
Rural Sweden [4] Moss 1.0
Industrial Sweden [4] Moss 7.6
Heavy industrial Sweden [4] Moss 400
Steel works Sweden [4] Moss 560
Urban USA [5]   10 - 30
Uninhabited USA [5]   0.1 - 3.2
Municipal waste [6] Mo(CO)6 in landfill gas 0.2 - 0.3

[1] Sullivan, R. J., Pollution Aspects of Chromium and its Compounds, 1969, Technical Report, Litton Systems Inc., Environmental Systems Division, Bethesda, Md. (Quoted in Schroeder, H. A., Balassa, J. J. and Tipton, I. H., J. Chronic Dis., 1970, 23, 481).
[2] Smith, A. C., J. Appl. Chem., 1958, 8, 636.
[3] Anderson, G., Grensfelt, P., IVL, Gothenburg B, 1973, 138.
(Quoted in J. Lener and B. Bibr, J. Hygiene, Epidemiology, Microbiol. and Immunol., 1984, 28, 405).
[4] Lindan, L., and Sundderg, K., SNV PM, 1974, 428.
(Quoted in J. Lener and B. Bibr, J. Hygiene, Epidemiology, Microbiol. and Immunol., 1984, 28, 405).
[5] Air Quality Data, National Air sampling Network, Ed. 1966, US DHEW, Public Health service.
[6] Feldmann, J., Cullen, W.R..,Occurrence of volatile transition metal compounds in landfill gas: Synthesis of molybdenum and Tungsten carbonyls in the environment, Environmental Science & Technology, 1997, 31, 2125-2129.

Mo in ambient air urban areas 0.01 – 0.03 microg Mo/m3
Rural areas 0.001 – 0.0032

Schroeder, H.A., A sensible look at air pollution by metals, Arch. Environ. Health, 1970, 21, 798 – 806.

Concentrations of molybdenum and other metals were determined in ambient air as part of an ongoing air-quality monitoring programme.the mass concentrations and metals speciation of ambient aerosols collected in Oxford, OH were compared with those collected in three urban centers (Cincinnati, Middletown, and Hamilton) in the Greater Cincinnati region. PM2.5 particles (< 2.5 microm) typically originates from the combustion of fossil fuels for power and transportation and from manufacturing processes. The mean PM2.5, PM10 and TSP mass concentrations (microg m-3) of the samples collected in 2005 in Oxfordwere: PM2.5, 15.6±8.1, PM10, 16.2±7.3; TSP, 37.0±7.8. The PM2.5 contributed 95% to PM10 and 60% to TSP (total suspended solids). Arsenic, antimony, cobalt, and lead were predominantly contained in PM2.5; cadmium, chromium, iron, nickel, molybdenum, silicon, vanadium, and zinc in PM10.. Since these metals are typically associated with anthropogenic metals emissions (traffic, combustion of fossil fuels, industry) and it was expected that these metals would be present in the smaller particle size ranges.

Wojas, B. and Almquist, C., Mass concentrations and metals speciation of PM2.5, PM10, and total suspended solids in Oxford, Ohio and comparison with those from metropolitan sites in the Greater Cincinnati region, Atmospheric Environment, 2007, 41, 9064-9078.

Molybdenum atmospheric deposition in mosses

The deposition of manganese, molybdenum and nickel in the county of Obrenovac (Serbia) in four moss taxa (Bryum argenteum, Bryum capillare, Brachythecium sp., and Hypnum cupressiforme) is presented. The distribution of average heavy metal content in all mosses in the county of Obrenovac is presented on maps, while the long-term atmospheric deposition (in the mosses Bryum argenteum and B. capillare) and short term atmospheric deposition (in the mosses Brachythecium sp. and Hypnum cupressiforme) are discussed and given in tabular form. Areas of the highest contaminations are highlighted

Vukojevic, V., Sabovljevic, M., Sabovljevic, A., Mihajlovic, N., Drazic, G., and Vucinic, Z., Determination of Heavy Metal Deposition in the County of Obrenovac (Serbia) Using Mosses As Bioindicators. IV. Manganese (Mn), Molybdenum (Mo), and Nickel (Ni), Archives of Biological Sciences, 2009, 61, 835-845.

Airborne dust: Airborne concentrations of metals and total dust during solid catalyst loading and unloading operations at a petroleum refinery

Workers handle catalysts extensively at petroleum refineries throughout the world each year; however, little information is available regarding the airborne concentrations and plausible exposures during this type of work. In this paper, we evaluated the airborne concentrations of 15 metals and total dust generated during solid catalyst loading and unloading operations at one of the largest petroleum refineries in the world using historical industrial hygiene samples collected between 1989 and 2006.

The total dust and metals, which included aluminum, cadmium, chromium, cobalt, copper, iron, lead, manganese, molybdenum, nickel, platinum, silicon, silver, vanadium, and zinc, were evaluated in relation to the handling of four different types of solid catalysts associated with three major types of catalytic processes.

Consideration was given to the known components of the solid catalysts and any metals that were likely deposited onto them during use.

A total of 180 analytical results were included in this analysis, representing 13 personal and 54 area samples.

Of the long-term personal samples, airborne concentrations of metals ranged from <0.001 to 2.9mg/m3, and, in all but one case, resulted in concentrations below the current U.S. Occupational Safety and Health Administration's Permissible Exposure Limits and the American Conference of Governmental Industrial Hygienists' Threshold Limit Values.

The arithmetic mean total dust concentration resulting from long-term personal samples was 0.31mg/m3.

The data presented here are the most complete set of its kind in the open literature, and are useful for understanding the potential exposures during solid catalyst handling activities at this petroleum refinery and perhaps other modern refineries during the timeframe examined.


“In conclusion, the data reported here, which are the most complete set in the open literature to date, consist of both personal and area measurements of 15 metals and total dust collected during the loading and unloading of four different types of solid catalysts (Ni–Mo, Co–Mo, Pt–Re, and zeolite) associated with three major types of catalytic processes (desulfurization, reformation, and fluidized catalytic cracking). The findings of this analysis suggest that the airborne concentrations of metals and total dust generated during solid catalyst loading and unloading at this petroleum refinery, and perhaps other modern refineries during the timeframe examined, were generally low. Further research is recommended, though, to help characterize the levels across the industry. Funding This work was partially funded by Hess Corporation, an energy company that has been involved in litigation related to possible catalyst exposure. Conflict of interest statement One of the authors has served as an expert witness for Hess Corporation on matters relating to industrial hygiene, exposure assessment, risk assessment, and/or toxicological issues related to catalysts.”
Molybdenum concentrations (mg/m3): Heavy distillate desulfurization area Sample result (mg/m3) Unloading Min. = 0.022 Mean = 0.034 Max. = 0.051.Loading Min. = 0.27 Max. = 0.61

Lewis, Ryan C., Gaffney, Shannon H., Le, Matthew H., Unice, Ken M., and Paustenbach, Dennis J., Airborne concentrations of metals and total dust during solid catalyst loading and unloading operations at a petroleum refinery, International Journal of Hygiene and Environmental Health, 2012, 215, 514-521.

See also

Hery, M., Gerber, J.M., Hubert, G., Hecht, G., Diebold, F., Honnert, B., Moulut, J.C., 1994.Exposure to metallic catalyst dust: manufacturing and handling of catalysts in the chemical industry. Ann. Occup. Hyg. 38, 119–135.

Methane sensor MoO3

Methane Gas Detection in Environment Using Shape Dependent alpha-MoO3 Nanosensor

In this work, one dimensional (1-D) orthorhombic molybdenum trioxide (alpha-MoO3) nanostructures were synthesized using sol-gel technique and deposited on alumina substrates pre-patterned with interdigitated gold electrodes. Microstructure characterization was done using X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), and Micro Raman spectroscopy techniques. Different morphology viz nanospheres, nanoplatelets (300-600 nm) and nanobars (average length of 1 mu m, width of 100 nm and thickness of 100 nm) which are predominantly orthorhombic (alpha-MoO3) were obtained. The growth along (001) direction of the nanobars was enhanced by increasing the annealing temperature to 550 degrees C. The fabricated sensors were tested with methane gas at elevated temperatures of 300 degrees C. The structural and gas sensing properties of alpha-MoO3 nanostructures are correlated

Rakkesh, R. A., Prasad, A. K., Dash, S., Tyagi, A. K., and Balakumar, S., Methane Gas Detection in Environment Using Shape Dependent alpha-MoO3 Nanosensor, Solid State Physics, Pts 1 and 2, 2012, 1447, 249-250.

Users of the Database should be aware that inclusion of an abstract in the Database does not imply any IMOA endorsement of the accuracy or reliability of the reported data or the quality of a publication.