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Trace Metal Preconcentration using Chelating Resin Flow Injection resin injection

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Trace Metal Preconcentration using Chelating Resin Flow Injection resin injection Powered By Docstoc
					Copper speciation in the Stockholm
          Archipelago




             Kuria Ndung’u
     Applied Environmental Science
         Stockholm University
         Acknowledgements

Hans Borg       Kemikalieinspektionen-KEMI
Göran Lithner        Naturvårdsverket
Jörgen Ek        European Copper Institute
Karin Holm
Britta Eklund
Ken Bruland
Matthew Hurst
Kristen Buck
Russ Flegal
Speciation: Historical background
    Sensitive analytical techniques
       (AAS, ICP-OES/MS, ASV/CSV)




  Clean techniques and reliable data
            (last ca. 20 yrs)




  Ecotoxicologists: metal speciation
Trace metal clean sampling and analysis
     Trace metal clean methods
       Dissolved Cd and Pb in river water

                                 conventional



                                            TM clean methods




                                            Benoit, 1994
Contamination artifacts have seriously compromised the
reliability of many past and current analyses and in some
cases, metals have been measured at 100 times their true
concentration. Benoit et al., 1997
Free ion activity model (FIAM)




 Anderson & Morel, 1978, Paquin et al., 2002
  The Biotic Ligand Model




Paquin et al. 2002
Biotic ligands: Cell membrane




                     Sunda, 1988
                      Aquatic Cu speciation

         Inorganic Complexes                   Organic Complexes
           CuXi (e.g. CuCO3)                      CuL1 ,CuL2)




                                                               Particulate-Cu
                                      Cu2+                          Cu-P
 Aquatic chemistry


Biological effects

                                    Plankton

                                                     Filter feeders
           Adapted from Donat et al., 1994
              Synthetic Chelators




          EDTA                                        DTPA




                                     NTA
Multiple sources: Soaps & detergents, water treatment, metal finishing and plating
Natural Chelators




         Morel & Price, 2003
       Speciation Techniques

1. Ion selective electrodes (ISE)
       ([Mn+] >10-7 M)
 2. Voltammetry:
        Competing ligand equilibration
        Adsorptive cathodic stripping (CLE-CSV)

        Anodic stripping:
                      DPASV-HMDE
                      DPASV-GCDE
3. Others: Diffusive gradients in thin films (DGT)
       Chelating resins
Voltammetric speciation methods comparison
Analytical    Basis of             Species reactivity                 comments
method        distinguishing
              species
                                   Cu2+     CuL1        CuL2
                                   CuX

CLE-CSV          Equilibrium       labile   CuL1 & CuL2               Best
               competition with             determinable              characterizati
                 added ligand               depending on added        on of CuL
                                            ligand strength CuL      (“carrying
                                                                      capacity”)
DPASV-RGCDE                        labile   inert       Inert for
              Kinetics of CuL1                          kd< 1 s-1
              dissociation
DPASV-HMDE                         labile   inert       Inert for
                                                        kd< 0.1 s-1



              Modified from Donat et al., 1994
Differential pulse anodic stripping voltammetry
DPASV: Titration of BA-30 (Dumbarton Bdge)




                         Hurst and Bruland, 2005
                 Sampling sites
                                       S55

         S40
                            S57b
                     S50




   S67


S79b



                                             Säck harbor




               Bullandö Marina




                      Outside marina
         Sampling sites: Ancillary data
Site              date       pH    Salinity DOC    Cutot
                                   (‰)      (M)   (nM)
S-79b             29 Aug. 06 7.4   2.9     426     24
S-67              29 Aug. 06 7.9   4.3     388     22
S-40              29 Aug. 06 8.2   5.1     354     14
S-50              29 Aug. 06 8.5   6.0     330     8
S-55              20 Aug. 05 -     5.4             8
Reference station 22 Aug. 06 8.0   5.2     341     13.3
Säck Harbor       22 Aug. 06 8.1   5.4     363     14.2
Outside Bullandö 22 Aug. 06 8.0    4.9     370     16.4
Bullandö Marina   22 Aug. 06 8.0   4.9     367     49.7
Salinity, Cu and DOC gradient
                            6.0                                             25.0
DOC (mg/L) & Salinity (‰)
                                                                            20.0

                            4.0




                                                                                    Cu (nM)
                                                                            15.0
                                  S79B   S67
                                                                            10.0
                            2.0                     S40        S50
                                          Salinity                   S57B         S55
                                          ((DOC (mg/L                       5.0
                                          (Cu /nM

                            0.0                                             0.0
                                  S79B   S67        S40        S50   S55

                                               Sampling site
         Bullandö Marina




One of the biggest marinas in Sweden, ca. 1400 berths
Ligand pool “carrying capacity”

                                         inorganic complexation only

                  -9
 log [Cu2+ ] M




                                 possible cyanobacteria toxicity threshold
                 -11


                 -13
                           ambient [Cu tot] = 13.3 nM (0.84 g/L)

                 -15
                       0         30              60               90         120
                                         [Cu*T] (nM)

                                 Reference station
Ligand pool “carrying capacity”
                                        inorganic complexation only


                    -9
 log [Cu2+ ] (M)



                                       cyanobacteria toxicity threshold
                   -11



                   -13

                                      ambient [Cu tot]=49.7 nM (3.2 g/L)
                   -15
                         0   30         60               90               120
                                    [Cu*T ] (nM)

                             Bullandö Marina
                                                                    Summary
                                   Outside Bullandö Marina                                                                        Säck natural harbor



                   -9                                                                                             -9




                                                                                             log [Cu2+ ] (M)
   ] (M)




                  -11                                                                                            -11
2+
   log [Cu




                                                                                                                 -13
                  -13
                                                                                                                           ambient [Cutot]=14.2 nM (0.90 g/L)
                                                 ambient [Cu tot]=16.4 nM (1.04 g/L)
                                                                                                                 -15
                  -15
                                                                                                                       0     30            60           90        120
                        0         20        40         60        80       100          120
                                                                                                                                      [Cu*T] (nM)
                                                  [Cu*T] (nM)

                                       Bullandö marina                                                                         Reference station

                         -9
                                                                                                                  -9
log [Cu2+ ] (M)




                                                                                              log [Cu 2+ ] (M)
                        -11
                                                                                                                 -11


                        -13                                                                                      -13
                                                            [Cutot]=49.7 nM (3.2 g/L)
                                                                                                                             ambient [Cutot]=13.3 nM (0.84 g/L)

                        -15                                                                                      -15
                                                                                                                       0     30           60            90        120
                              0            30             60            90             120
                                                                                                                                     [Cu*T] (nM)
                                                     [Cu*T ] (nM)
“Cu concentration has doubled in the last decade”
                             1.6


                             1.4                             KEMI-2004
  Cu Concentration (ng/ml)




                                   EPA-1993
                             1.2
                                                         B
                                                                          This study
                              1
                                        B
                                                                              B

                                                                                       IOW (HELCOM)
                             0.8


                             0.6                                                             B


                                                                                       Landsort Deep
                             0.4
                                      1993             2004              2004-2006     1993-2005

                                                                  Year

                                   …..In the water samples the copper concentrations have generally
                doubled, while zinc concentrations have gone up with up to 6.5 times……(KEMI, 2006)
Cu speciation in the other marine waters
  Study area        Dissolved Cu   Complexed    Reference
                       (g/L))      Cu (% )
 Stockholm             0.8-3.2       >99.9      This study
 Archipelago
Gullmar Fjord                        >99.8      Croot, 2003
                      0.2-1.2
San Francisco         1.1-3.2        >99.9        Buck &
Bay(California)                                Bruland, 2005

  Cape Cod            0.3-3.4       90-99<     Moffett et al.,
 (Massachusetts)                                  1997

Narragansett            0.8          >99.9     Bruland et al.,
Bay(Rhode Island)                                  2000
              Conclusion
More than 99.9 % of the total dissolved copper in the
sites studied was organically complexed


The large excess (compared to Cutot) concentration of
Cu complexing ligands buffers the [Cu2+] to < 10-12 M
(< 0.1 ng/L) in all sites, an order of magnitude below
the toxicity threshold for microorganisms


We need more detailed (both spatially and temporally)
speciation studies on the Archipelago and the Baltic
Proper

				
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