DOEASP Workshop, Asheville, September 23-26, 2013
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DOEASP Workshop, Asheville, September 23-26, 2013 Selecting the Right S pecies , Fractions and Methods for Evaluating Remediation Effectiveness PowerPoint PPT Presentation


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DOEASP Workshop, Asheville, September 23-26, 2013 Selecting the Right S pecies , Fractions and Methods for Evaluating Remediation Effectiveness at Mercury Contaminated Sites Lisa Zhang Lian Liang Cebam Analytical, Inc . 2003 : UNEP declared mercury to be the pollutant of

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DOEASP Workshop, Asheville, September 23-26, 2013 Selecting the Right S pecies , Fractions and Methods for Evaluating Remediation Effectiveness

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Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

DOEASP Workshop, Asheville, September 23-26, 2013

Selecting

the Right Species, Fractions and Methods

for Evaluating Remediation Effectiveness

at Mercury Contaminated Sites

Lisa Zhang

Lian Liang

Cebam Analytical, Inc


Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

  • 2003: UNEP declared mercuryto be the pollutant of

    • greatest global concern due to its persistence in the environment and its negative effect on human health and the environment.

  • Mercurynow is even more important, because of

    • the UNEPGlobal Legally Binding Treaty on mercury officially launched in this year.

  • http://www.unep.org/hazardoussubstances/Mercury/Negotiations/tabid/3320/Default.aspx


Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

Mercury, an important global pollutant

Components of the global mercury cycle

Due to its biogeochemical cycling & accumulation in Biota


Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

  • How to put the treaty into practice toward

    • the banning of Hg.

  • Remediation will eventually be conducted at Hg

    • contaminated sites throughout the world.


  • Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    History of Mercury Use and Environmental Contamination

    at the Oak Ridge Y12 Plant

    Between 1950 and 1963:

    ~ 11 million kg of Elemental Hg used.

    ~ 194,100 kg lost to the ground (soil, sediment, storm sewers and old process buildings).

    The Area remains a source of mercury in Upper East Fork Poplar Creek

    http://www.esd.ornl.gov/programs/rsfa/index.shtml


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    • Cebamhas been working on the environmental monitoring

    • of Hg at the Oak Ridge site since1996.

    • The works focused mainly on analysis of Total Hg and Methyl

      • Hg in Waters, Fish, Sediments/Soils, and Air.

    • The data generated were traceable and defensible;

      • Recoveries were within 95 to 105% with RPD <5% for most samples analyzed.


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    However,

    although the monitoring data were at high quality,

    challenges

    were encountered.


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    • While mercury source reduction is a regulatory

    • driver, no direct linkage exists between mercury

    • source reduction and emerging stream protection

    • endpoints such as mercury levels in fish tissue.

    • (Mark J. Peterson, George R. Southworth, and Theresa J. Mathews, Mercury Challenges in the Environment: A

    • Technical Summit, October 22-23, 2009, Nashville, Tennessee).

    THg concentration in fish and water at Y-12, 1988-2008

    http://www.esd.ornl.gov/programs/rsfa/index.shtml

    Fish Hg level is not always sensitive to the changes of water Hg level.


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    • There is no linkage for THg concentration between waters and fish.

    • At contaminated sites, there is no model

      • relating methyl Hg and THg in water . (http://www.esd.ornl.gov/programs/rsfa/index.shtml).

      • Are the data obtained meaningful and useful for

        • characterization of the site?

        • reflecting the remediation activities of the site?


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    Due to the high bioaccumulation factor,

    fish Hg levels can be as high as 1 ppm (depending on size, species and environmental factors)in remote freshwaters (Hg <1.3 ppt) similar to those found in Hg reduced waters (Hg ≈ hundreds ppt) at the Oak Ridge site!

    How can we expect fish Hg level to decrease further, and use it to evaluate the remediation of the site?


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    • Remediation

    • Two primary methods:

    • Converting reactive Hg species into chemically inert

      • species such as HgS (themost stable form of Hg).

    • Binding reactive Hg species on various adsorbent

      • materials such as reactive carbon…

    • Therefore, The right way for evaluation:

    • Selecting biogeochemical reactive Hg species/ fractions sensitive to reflect the site and link to methylation for monitoring.

    • Determining how much reactive Hg species/ fractions reduced after remediation.


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    • What Hg species/fractions in waters should be selected?

    • Total Hg (THg)?

    • Elemental Hg (Hg0)?

    • Dimethyl Hg (DMHg)?

    • Monomethyl Hg (MeHg)?

    • Reactive inorganic Hg2+ (RHg)?

    • Depending on the geochemical conditions of the site.


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    Comparison of Hg species

    RHg, an important species/fractions, was missed in the monitoring for past years!


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    Comparison of MeHg level

    in the Oak Ridge and others sites.

    Further, the ratio of MeHg to THg even often shows a reverse pattern, i.e. at higher THg concentrations, the ratio is lower at the Oak Ridge site.


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    • Typical chromatography of Hg speciation in water

    • samples from different superfund sites

    • (MeHg, methyl Hg; RHg, biogeochemically reactive Hg2+)

      • A. xxxxxxxx water of Oak Ridge Y-12 site

      • B. surface water of South River, VA

      • C. pore water of Patrick Bayou, TX


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    • RHg: high solubility, mobility, bioavailability, and

      • methylation potential, RHg can directly and immediately

      • reflect the change of Hg levels of contaminated sites.

    • RHg: the predominant reactive Hg species in terms of

      • mass, RHg may be the best species/fractions to use for

      • remediation evaluation at this Hg contaminated sites.

      • However, the use of RHg measurement has not gained widespread acceptance, even after over two decades of practice. The lack of specific analytical methods useful and reliable for identifying and quantifying RHg is most likely the cause of this.


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    In the past, the classic Sn2+ reduction method has been virtually the only method used for determination of RHg.

    Hg2+ + Sn2+ → Hg0↑

    Volatile Hg0is measured by purge/trap/CVAFS (EPA method 1631).

    Due to insufficient understanding of the reaction conditions, the method was

    inadequately used, resulting in negatively biased results,


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    Unpreserved Clean Water

    Effect of purge time on recoveries of SnRHg (RHg results by Sn2+ reduction) in 12 clean river water samples. Results of RHg by ethylation were used as 100% recoveries.


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    Industrial Wastewater with complex matrices

    Effect of purge time on recoveries of SnRHg (RHg results by Sn2+ reduction)

    in 12 Hg impacted industrial wastewaters. Results of RHg by ethylation were

    used as 100% recoveries


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    To fill the gap, to ensure reliable results of RHg, Cebam adapted a method by

    direct ethylation/GC separation/CVAFS detection

    Hg2+ + 2C2H5 → Hg(C2H5)2↑

    Volatile Hg(C2H5)2is measured by purge/trap/GC/CVAFS.

    Methodology detailed in

    Liang L., Horvat M., and Bloom N.S., 1994, Talanta, 41,3,371.

    Liang L., Bloom N.S., and Horvat M., 1994, Clin. Chem., 40,4,602


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    Comparison of ethylation and Sn2+ reduction methods

    for determination of RHg

    The ethylation method is significantly advanced over the Sn2+ reduction method


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    RHg by ethylation method

    the right species/fractions for

    evaluating remediation efficiency

    at the Y-12 site

    ?


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    Application of the ethylation method to the determination of RHg in waters

    Sampling locations on the river Idrijca

    From the Idrijca River, Slovenia. The Idrijca River drains the area of the Idrijca Hg mine, now closed but formerly the world’s second largest Hg mine. This river water contains a significant amount of Hg0 from the mine.


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    • Concentrations of Hg species/fractions measured in the River Idrija in Slovenia. Using the ethylation method, positive and negative bias encountered

    • by the Sn2+ reduction method, was eliminated for determination of

    • RHg in this Hg contaminated river, resulting in meaningful useful data.


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    • Other applications Cebam processed

      • THg

      • MeHg

      • RHg

      • Hg0

    • 300 pore waters from Patrick Bayou Superfund Site, TX

    • 400 surface waters from the St. Louis River, MN

    • 300industrial waste waters from the United States, Europe, and Asia.

  • RHgresults were found to be valuable and meaningful for better

    • characterization and evaluation of remediation of the sites.


  • Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    Applications of RHg in matrices other than waters

    • Soil,

    • Sediments

    • Crude oils

    • Refinery wastes

  • Key challenge

    • How to selectively extractRHg from various matrices without species shift?


  • Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    Determination ofRHg in soil/sediment extracts

    • To meet project needs, Different Extraction Procedures

    • Cebam developed/improved procedures

    • TCLP, EPA Method 1311. 1992,

    • Selective Sequential Extraction procedures published by experts in the world

      Promising results were obtained.


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    Selective Sequential Procedures

    used in Cebam’s Hg Lab for extraction of RHg


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    • Are there direct linkages between

      • RHg and MeHg?

      • RHg and fish Hg?


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    In remote lakes, research found that decreases in fish Hg are related to the

    atmospheric loading of Hg and SO4 because both substrates are limiting in these

    systems (Hrabik and Watras 2002; Watras and Morrison, 2008; Watras 2009). The Metallicus project in Canada made similar findings.

    Hg0→ Evaporation→ Oxidation→ RHg formation → Wet deposition→ Methylation → Fish accumulation


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    • Monitoring RHg to provide meaningful results with linkage to

      • Methylation

      • Fish Hg


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    • We recommend to consider RHg for routine monitoring of

    • water, soil and sediment samples

      • at the Oak Ridge site.

    • We need supports to develop useful procedures to meet project needs!


    Doeasp workshop asheville september 23 26 2013 selecting the right s pecies fractions and methods for evaluating remediation effectiveness

    Questions?

    Thank you!

    Cebam Analytical, Inc


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