Environmental Chemistry Environmental Chemistry Society
Environmental problems - Chemical approaches
RESEARCH ARTICLE (Open Access)

Derivation of ecological standards for risk assessment of molybdate in soil

Koen Oorts A G , Erik Smolders B , Steve P. McGrath C , Cornelis A.M. van Gestel D , Michael J. McLaughlin E and Sandra Carey F
+ Author Affiliations
- Author Affiliations

A ARCHE, Liefkensstraat 35D, BE-9032 Ghent (Wondelgem), Belgium.

B Department of Earth and Environmental Sciences, Division of Soil and Water Management, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, BE-3001 Leuven, Belgium.

C Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, UK.

D Department of Ecological Science, Faculty of Earth and Life Science, VU University Amsterdam, De Boelelaan 1085, NL-1081 HV Amsterdam, Netherlands.

E CSIRO Land and Water, Contaminant Chemistry and Ecotoxicology Program, Waite Campus, Waite Road, Urrbrae, SA 5064, Australia.

F International Molybdenum Association, 4 Heathfield Terrace, London, W4 4JE, UK.

G Corresponding author. Email: koen.oorts@arche-consulting.be

Environmental Chemistry 13(1) 168-180 https://doi.org/10.1071/EN15086
Submitted: 24 April 2015  Accepted: 31 July 2015   Published: 4 November 2015

Environmental context. In order to assess the potential risks of elevated molybdenum concentrations in soil due to anthropogenic activities, toxicity thresholds must be known and environmental criteria defined. Setting such criteria for metals is not straightforward because of varying natural background concentrations and differences in toxicity between typical laboratory and field conditions and across soil types. Toxicity data and models were derived that account for these parameters so that soil quality criteria can be derived based on total molybdenum concentrations in soil.

Abstract. An extensive testing programme on the toxicity of sodium molybdate dihydrate in soil was initiated to comply with the European REACH Regulation. The molybdate toxicity was assayed with 11 different bioassays, 10 different soils, soil chemical studies on aging reactions, and toxicity tests before and after 1-year equilibration in field conditions. Differences in molybdate toxicity among soils were best explained by soil pH and clay content. A correction factor of 2.0 was selected to account for the difference in molybdate toxicity between laboratory and field conditions due to leaching and aging processes. Toxicity thresholds were determined as the HC5–50 (median hazardous concentration for 5 % of the species, i.e. median 95 % protection level) derived from the species sensitivity distribution of ecotoxicity data after bioavailability corrections. Uncertainty analysis illustrated that the HC5–50 provides a robust and ecologically relevant predicted no-effect concentration (PNEC) for risk characterisation. The 10th and 90th percentiles for site-specific PNEC values in European agricultural soil are 10.7 and 168 mg Mo kg–1 dry weight respectively based on a large survey of metal concentrations and soil properties in arable land soils. Total soil Mo concentrations in these soils are below corresponding PNEC values at most locations, suggesting no regional risks of molybdate to soil organisms at this scale. The information presented can be used in the EU risk-assessment framework as well as for national and international regulatory purposes for the setting of soil quality criteria based on total molybdenum concentrations, soil pH and clay content.

Additional keywords: bioavailability, soil ecotoxicity.


References

[1]  D. I. Arnon, P. R. Stout, The essentiality of certain elements in minute quantity for plants with special reference to copper. Plant Physiol. 1939, 14, 371.
The essentiality of certain elements in minute quantity for plants with special reference to copper.CrossRef | 1:CAS:528:DyaA1MXmtVagtg%3D%3D&md5=f58a800ddea7d037950570463f9c8b2fCAS | 16653564PubMed |

[2]  R. J. P. Williams, J. da Silva, The involvement of molybdenum in life. Biochem. Biophys. Res. Commun. 2002, 292, 293.
The involvement of molybdenum in life.CrossRef | 1:CAS:528:DC%2BD38XitFeisb8%3D&md5=746e8e1a964e0e00e506da2c8918549cCAS |

[3]  D. R. Lide, Handbook of Chemistry and Physics, 90th edn 2009 (CRC Press LLC: Boca Raton, FL)

[4]  Z. L. L. He, X. E. Yang, P. J. Stoffella, Trace elements in agroecosystems and impacts on the environment. J. Trace Elem. Med. Biol. 2005, 19, 125.
Trace elements in agroecosystems and impacts on the environment.CrossRef | 1:CAS:528:DC%2BD28XhslagtrY%3D&md5=173607d9d37c4602db6e11feaab5da70CAS |

[5]  J. Buekers, J. Mertens, E. Smolders, Toxicity of the molybdate anion in soil is partially explained by effects of the accompanying cation or by soil pH. Environ. Toxicol. Chem. 2010, 29, 1274.
| 1:CAS:528:DC%2BC3cXpsFCqu70%3D&md5=3b0fcb0ee920277f2a91b7b76a092447CAS | 20821569PubMed |

[6]  A. D. Anbar, Molybdenum stable isotopes: observations, interpretations and directions. Rev. Mineral. Geochem. 2004, 55, 429.
Molybdenum stable isotopes: observations, interpretations and directions.CrossRef |

[7]  A. Bibak, O. K. Borggard, Molybdenum adsorption by aluminium and iron oxides and humic acid. Soil Sci. 1994, 158, 323.
Molybdenum adsorption by aluminium and iron oxides and humic acid.CrossRef | 1:CAS:528:DyaK2MXis1ans7c%3D&md5=53cad20182961799e335386504c1bf9aCAS |

[8]  S. Goldberg, H. S. Forster, C. L. Godfrey, Molybdenum adsorption on oxides, clay minerals, and soils. Soil Sci. Soc. Am. J. 1996, 60, 425.
Molybdenum adsorption on oxides, clay minerals, and soils.CrossRef | 1:CAS:528:DyaK28Xitleqs74%3D&md5=0c47a4311a294d38200545422a639274CAS |

[9]  S. Goldberg, S. M. Lesch, D. L. Suarez, Predicting molybdenum adsorption by soils using soil chemical parameters in the constant capacitance model. Soil Sci. Soc. Am. J. 2002, 66, 1836.
Predicting molybdenum adsorption by soils using soil chemical parameters in the constant capacitance model.CrossRef | 1:CAS:528:DC%2BD38XoslKhsLg%3D&md5=d39d58c040c9903ed62912798603b973CAS |

[10]  S. Goldberg, H. S. Forster, Factors affecting molybdenum adsorption by soils and minerals. Soil Sci. 1998, 163, 109.
Factors affecting molybdenum adsorption by soils and minerals.CrossRef |

[11]  Regulation (EC) Number 1907/2006 concerning the Registration, Evaluation, Authorisation and Restriction of Chemical substances (REACH) 2006 (European Commission: Brussels, Belgium).

[12]  Guidance on Information Requirements and Chemical Safety Assessment. Chapter R.7.11. Effects on Terrestrial Organisms 2014 (European Chemicals Agency: Helsinki, Finland). Available at http://echa.europa.eu/documents/10162/13632/information_requirements_r7c_en.pdf [Verified 19 September 2015].

[13]  Guidance on Information Requirements and Chemical Safety Assessment. Appendix R.7.13–2: Environmental Risk Assessment for Metals and Metal Compounds 2008 (European Chemicals Agency: Helsinki, Finland). Available at http://echa.europa.eu/documents/10162/13632/information_requirements_r7_13_2_en.pdf [Verified 19 September 2015].

[14]  K. Oorts, U. Ghesquiere, K. Swinnen, E. Smolders, Soil properties affecting the toxicity of CuCl2 and NiCl2 for soil microbial processes in freshly spiked soils. Environ. Toxicol. Chem. 2006, 25, 836.
Soil properties affecting the toxicity of CuCl2 and NiCl2 for soil microbial processes in freshly spiked soils.CrossRef | 1:CAS:528:DC%2BD28XitVais74%3D&md5=cfc09d39d98863a192a287ab61ff29daCAS | 16566169PubMed |

[15]  J. Song, F. J. Zhao, S. P. McGrath, Y. M. Luo, Influence of soil properties and aging on arsenic phytotoxicity. Environ. Toxicol. Chem. 2006, 25, 1663.
Influence of soil properties and aging on arsenic phytotoxicity.CrossRef | 1:CAS:528:DC%2BD28Xlt1Whsbw%3D&md5=4d6c0b7f47c4afd7037776b1a1514c59CAS | 16764487PubMed |

[16]  P. Criel, K. Lock, H. Van Eeckhout, K. Oorts, E. Smolders, C. R. Janssen, Influence of soil properties on copper toxicity for two soil invertebrates. Environ. Toxicol. Chem. 2008, 27, 1748.
Influence of soil properties on copper toxicity for two soil invertebrates.CrossRef | 1:CAS:528:DC%2BD1cXovFWjtb8%3D&md5=f84d3c43259c209e1cac1aee4ee2a14dCAS | 18290689PubMed |

[17]  K. Lock, N. Waegeneers, E. Smolders, P. Criel, H. Van Eeckhout, C. R. Janssen, Effect of leaching and aging on the bioavailability of lead to the springtail Folsomia candida. Environ. Toxicol. Chem. 2006, 25, 2006.
Effect of leaching and aging on the bioavailability of lead to the springtail Folsomia candida.CrossRef | 1:CAS:528:DC%2BD28XnvFait74%3D&md5=f54c26d74e76f07ea7226ad0d1c15385CAS | 16916018PubMed |

[18]  K. Oorts, H. Bronckaers, E. Smolders, Discrepancy of the microbial response to elevated copper between freshly spiked and long-term contaminated soils. Environ. Toxicol. Chem. 2006, 25, 845.
Discrepancy of the microbial response to elevated copper between freshly spiked and long-term contaminated soils.CrossRef | 1:CAS:528:DC%2BD28XitVais78%3D&md5=52531c0368a6926e5d07ee75800c95c9CAS | 16566170PubMed |

[19]  L. A. Wendling, J. K. Kirby, M. J. McLaughlin, Aging effects on cobalt availability in soils. Environ. Toxicol. Chem. 2009, 28, 1609.
Aging effects on cobalt availability in soils.CrossRef | 1:CAS:528:DC%2BD1MXovFersbk%3D&md5=94942b53d5bc7e3b777e2f73d497f015CAS | 19642829PubMed |

[20]  F. Degryse, J. Buekers, E. Smolders, Radio-labile cadmium and zinc in soils as affected by pH and source of contamination. Eur. J. Soil Sci. 2004, 55, 113.
Radio-labile cadmium and zinc in soils as affected by pH and source of contamination.CrossRef | 1:CAS:528:DC%2BD2cXisFCgtbk%3D&md5=a0795bcffcd2919d838aa6dc7a4adbe0CAS |

[21]  Y. B. Ma, E. Lombi, M. J. McLaughlin, I. W. Oliver, A. L. Nolan, K. Oorts, E. Smolders, Aging of nickel added to soils as predicted by soil pH and time. Chemosphere 2013, 92, 962.
Aging of nickel added to soils as predicted by soil pH and time.CrossRef | 1:CAS:528:DC%2BC3sXltFCrtLs%3D&md5=f155998faa096398c1dd0193a3e9655bCAS |

[22]  E. Smolders, K. Oorts, P. van Sprang, I. Schoeters, C. R. Janssen, S. P. McGrath, M. J. McLaughlin, Toxicity of trace metals in soil as affected by soil type and aging after contamination: using calibrated bioavailability models to set ecological soil standards. Environ. Toxicol. Chem. 2009, 28, 1633.
Toxicity of trace metals in soil as affected by soil type and aging after contamination: using calibrated bioavailability models to set ecological soil standards.CrossRef | 1:CAS:528:DC%2BD1MXovFertr4%3D&md5=5e3e2c3f9d5174628be5dab9c3024447CAS | 19301943PubMed |

[23]  N. Xu, W. Braida, C. Christodoulatos, J. P. Chen, A review of molybdenum adsorption in soils/bed sediments: speciation, mechanism, and model applications. Soil Sediment Contam. 2013, 22, 912.
A review of molybdenum adsorption in soils/bed sediments: speciation, mechanism, and model applications.CrossRef | 1:CAS:528:DC%2BC3sXktVOqt7s%3D&md5=3c75537c3e3ed4c0ef314967eacc628dCAS |

[24]  M. Díez-Ortiz, I. Giska, M. Groot, E. M. Borgman, C. A. M. Van Gestel, Influence of soil properties on molybdenum uptake and elimination kinetics in the earthworm Eisenia andrei. Chemosphere 2010, 80, 1036.
Influence of soil properties on molybdenum uptake and elimination kinetics in the earthworm Eisenia andrei.CrossRef | 20674662PubMed |

[25]  C. A. M. van Gestel, E. Borgman, R. A. Verweij, M. D. Ortiz, The influence of soil properties on the toxicity of molybdenum to three species of soil invertebrates. Ecotoxicol. Environ. Saf. 2011, 74, 1.
The influence of soil properties on the toxicity of molybdenum to three species of soil invertebrates.CrossRef | 1:CAS:528:DC%2BC3cXhtlKrs7fK&md5=8a147af9eccfbd8bb816c77eefd7ca61CAS |

[26]  C. A. M. Van Gestel, M. D. Ortiz, E. Borgman, R. A. Verweij, The bioaccumulation of molybdenum in the earthworm Eisenia andrei: influence of soil properties and ageing. Chemosphere 2011, 82, 1614.
The bioaccumulation of molybdenum in the earthworm Eisenia andrei: influence of soil properties and ageing.CrossRef | 1:CAS:528:DC%2BC3MXit12jsrg%3D&md5=d8dd91d3839e81f70f2b8ef81a2fc39aCAS |

[27]  C. A. M. van Gestel, S. P. McGrath, E. Smolders, M. D. Ortiz, E. Borgman, R. A. Verweij, J. Buekers, K. Oorts, Effect of long-term equilibration on the toxicity of molybdenum to soil organisms. Environ. Pollut. 2012, 162, 1.
Effect of long-term equilibration on the toxicity of molybdenum to soil organisms.CrossRef | 1:CAS:528:DC%2BC38Xps1Skuw%3D%3D&md5=aa35bb51bc1d1d553e8f7803ab6c9ac9CAS |

[28]  S. P. McGrath, C. Mico, F. J. Zhao, J. L. Stroud, H. Zhang, S. Fozard, Predicting molybdenum toxicity to higher plants: estimation of toxicity threshold values. Environ. Pollut. 2010, 158, 3085.
Predicting molybdenum toxicity to higher plants: estimation of toxicity threshold values.CrossRef | 1:CAS:528:DC%2BC3cXhtFamu7nL&md5=a1e39f217ab60b41c29a829831511fc7CAS | 20656390PubMed |

[29]  S. P. McGrath, C. Mico, R. Curdy, F. J. Zhao, Predicting molybdenum toxicity to higher plants: influence of soil properties. Environ. Pollut. 2010, 158, 3095.
Predicting molybdenum toxicity to higher plants: influence of soil properties.CrossRef | 1:CAS:528:DC%2BC3cXhtFamu7nE&md5=15f2a68a535b7bf92266f400e1afde12CAS | 20656387PubMed |

[30]  J. Buekers, E. Smolders, Toxicity and Bioavailability of Molybdenum in Terrestrial Environments: Micro-organisms. Final Report to the International Molybdenum Association (IMOA) 2009 (University of Leuven).

[31]  ISO-11269–1, Soil Quality – Determination of the Effects of Pollutants on Soil Flora. Part 1. Method for the Measurement of Inhibition of Root Growth 1995 (International Organization for Standardization: Geneva).

[32]  ISO-11269–2, Soil Quality – Determination of the Effects of Pollutants on Soil Flora. Part 2. Effects of Contaminated soil on the Emergence and Early Growth of Higher Plants 1995 (International Organization for Standardization: Geneva).

[33]  OECD-208, Terrestrial Plant Test: Seedling Emergence and Seedling Growth Test 2006 (Organisation for Economic Co-operation and Development: Paris).

[34]  OECD-222, Earthworm Reproduction Test (Eisenia fetida/Eisenia andrei) 2004 (Organisation for Economic Co-operation and Development: Paris).

[35]  OECD-220, Enchytraeid Reproduction Test 2004 (Organisation for Economic Co-operation and Development: Paris).

[36]  ISO-11267. Soil Quality – Inhibition of Reproduction of Collembola (Folsomia candida) by Soil Pollutants 1999 (International Organization for Standardization: Geneva).

[37]  OECD-216, Soil Microorganisms: Nitrogen Transformation Test 2000 (Organisation for Economic Co-operation and Development: Paris).

[38]  OECD-217, Soil Microorganisms: Carbon Transformation Test 2000 (Organisation for Economic Co-operation and Development: Paris).

[39]  Guidance on Information Requirements and Chemical Safety Assessment. Chapter R.10: Characterisation of Dose [Concentration]–Response for Environment 2008 (European Chemicals Agency: Helsinki, Finland). Available at http://echa.europa.eu/documents/10162/13632/information_requirements_r10_en.pdf [Verified 19 September 2015].

[40]  J. K. Kirby, M. J. McLaughlin, Y. B. Ma, B. Ajiboye, Aging effects on molybdate lability in soils. Chemosphere 2012, 89, 876.
Aging effects on molybdate lability in soils.CrossRef | 1:CAS:528:DC%2BC38XoslGqsrk%3D&md5=6c0371b748c7fb9b8e1b60673936cb30CAS | 22704209PubMed |

[41]  C. Reimann, M. Birke, A. Demetriades, P. Filzmoser, P. O’Connor (Eds), Chemistry of Europe’s Agricultural Soils – Part A: Methodology and Interpretation of the GEMAS Data Set – Geologisches Jahrbuch, B 102 2014 (Schweizerbarth: Hanover).

[42]  R. F. Brennan, Residual value of molybdenum for wheat production on naturally acidic soils of Western Australia. Aust. J. Exp. Agric. 2006, 46, 1333.
Residual value of molybdenum for wheat production on naturally acidic soils of Western Australia.CrossRef | 1:CAS:528:DC%2BD28XpsFWltbk%3D&md5=37d38b55561401633ce40bd84cd0f950CAS |

[43]  N. J. Barrow, T. C. Shaw, Factors affecting long-term effectiveness of phosphate and molybdate fertilizers. Commun. Soil Sci. Plant Anal. 1974, 5, 355.
Factors affecting long-term effectiveness of phosphate and molybdate fertilizers.CrossRef |

[44]  N. J. Barrow, T. C. Shaw, Slow reactions between soil and anions. 4. Effect of time and temperature of contact between soil and molybdate on uptake of molybdenum by plants and on molybdate concentration in soil solution. Soil Sci. 1975, 119, 301.
Slow reactions between soil and anions. 4. Effect of time and temperature of contact between soil and molybdate on uptake of molybdenum by plants and on molybdate concentration in soil solution.CrossRef | 1:CAS:528:DyaE2MXhsFCnsL8%3D&md5=4cf3313f239b38a95e2342c56d31aeceCAS |

[45]  N. J. Barrow, P. J. Leahy, I. N. Southey, D. B. Purser, Initial and residual effectiveness of molybdate fertilizer in two areas of south-western Australia. Aust. J. Agric. Res. 1985, 36, 579.
Initial and residual effectiveness of molybdate fertilizer in two areas of south-western Australia.CrossRef | 1:CAS:528:DyaL2MXlt1agtLc%3D&md5=8fdc4dc0108d4efb916aa3533d6c7d79CAS |

[46]  F. Lang, M. Kaupenjohann, Immobilisation of molybdate by iron oxides: effects of organic coatings. Geoderma 2003, 113, 31.
Immobilisation of molybdate by iron oxides: effects of organic coatings.CrossRef | 1:CAS:528:DC%2BD3sXos1Ohuw%3D%3D&md5=63f7ef3833489f29b871e27774f1aa60CAS |

[47]  D. P. Stevens, M. J. McLaughlin, T. Heinrich, Determining toxicity of lead and zinc runoff in soils: salinity effects on metal partitioning and on phytotoxicity. Environ. Toxicol. Chem. 2003, 22, 3017.
Determining toxicity of lead and zinc runoff in soils: salinity effects on metal partitioning and on phytotoxicity.CrossRef | 1:CAS:528:DC%2BD3sXps1eltbs%3D&md5=4a67119f16968064f5f2dd5f667a9f37CAS | 14713044PubMed |

[48]  M. Bongers, B. Rusch, C. A. M. Van Gestel, The effect of counterion and percolation on the toxicity of lead for the springtail Folsomia candida in soil. Environ. Toxicol. Chem. 2004, 23, 195.
The effect of counterion and percolation on the toxicity of lead for the springtail Folsomia candida in soil.CrossRef | 1:CAS:528:DC%2BD2cXjvVKluw%3D%3D&md5=4695a40f8b6c178b047dafaf64cebe76CAS | 14768885PubMed |

[49]  K. Oorts, U. Ghesquiere, E. Smolders, Leaching and aging decrease nickel toxicity to soil microbial processes in soils freshly spiked with nickel chloride. Environ. Toxicol. Chem. 2007, 26, 1130.
Leaching and aging decrease nickel toxicity to soil microbial processes in soils freshly spiked with nickel chloride.CrossRef | 1:CAS:528:DC%2BD2sXls1yjsb4%3D&md5=0151c1508787abb8a86a569c0d2a6e44CAS | 17571677PubMed |

[50]  I. Kádár, Effect of heavy metal load on soil and crop. Acta Agronomica Hungarica 1995, 43, 3.

[51]  P. A. Biacs, H. G. Daood, I. Kadar, Effect of Mo, Se, Zn, and Cr treatments on the yield, element concentration, and carotenoid content of carrot. J. Agric. Food Chem. 1995, 43, 589.
Effect of Mo, Se, Zn, and Cr treatments on the yield, element concentration, and carotenoid content of carrot.CrossRef | 1:CAS:528:DyaK2MXktFehtbw%3D&md5=2957189231170f70ba6d63ddea6c08a9CAS |

[52]  F. Nyarai-Horvath, T. Szalai, I. Kadar, P. Csatho, Germination characteristics of pea seeds originating from a field trial treated with different levels of harmful elements. Acta Agronomica Hungarica 1997, 45, 147.
| 1:CAS:528:DyaK2sXls1WjtLg%3D&md5=a0beb6274b7822d4a8594681577cedd8CAS |

[53]  I. Kádár, L. Szabo, J. Sarkadi, Contamination of food chains with heavy metals and harmful elements. Project report 1998 (Hungarian Academy of Sciences, Research Institute of Soil Science and Agrochemistry: Budapest) [in Hungarian].

[54]  World Reference Base for Soil Resources. World Soil Resources Report 84 1998 (Food and Agriculture Organization, International Soil and Reference Information Center, International Society of Soil Science: Rome, Italy).


Full Text PDF (1.5 MB) Export Citation Cited By (3)