| 1. |
- Hoppe, Sabina, et al.
(författare)
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Soft and sour : The challenge of setting environmental quality standards for bioavailable metal concentration in Fennoscandinavian freshwaters
- 2015
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Ingår i: Environmental Science and Policy. - : Elsevier BV. - 1462-9011 .- 1873-6416. ; 54, s. 210-217
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Tidskriftsartikel (refereegranskat)abstract
- The European Union Water Framework Directive (WFD) requires member states to ensure that all inland and coastal waters achieve 'good' water quality status. To this end, the WFD has set environmental quality standards (EQS) or Water quality criteria (WQC) for priority pollutants that include the four metals Cd, Ni, Pb and Hg. Many states have also chosen to set EQS for Cu and Zn. The use of bioavailability models to set EQS, paves the way for accepting higher local metal concentrations in waters where metal bioavailability is deemed low. The Biotic Ligand Model (BLM) concept has been proposed as a tool for estimating metal bioavailability and for calculating local EQS in the EU guidance document. The BLM estimates metal bioavailability based on the dissolved metal concentration and key ancillary water chemistry parameters (acidity, hardness and organic carbon content). The BLMs developed so far, have only been validated for water chemistry input parameters typical of Central Europe. However, the pH, alkalinity and dissolved organic carbon levels of a significant fraction of Fennoscandinavian (Finland, Norway and Sweden) freshwaters are outside the calibration range of currently available BLMs. The levels of Ca2+, alkalinity and pH in 75%, 29% and 22%, respectively, of the ca. 2500 Fennoscandinavian freshwater bodies investigated in this survey were outside the calibration range of tested BLMs. Moreover, a comparison of the ability of the tested BLMs to predict the acute and chronic copper toxicity to Daphnia magma and Rainbow trout indicated that the BLMs should be used with caution outside their current validation range. We conclude that more work is needed to extend the application of BLMs in the practical risk assessment to encompass a broader range of European freshwater bodies.
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| 2. |
- Ndungu, Kuria
(författare)
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Dissolved silver in the Baltic Sea
- 2011
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Ingår i: Environmental Research. - : Elsevier BV. - 0013-9351 .- 1096-0953. ; 111:1, s. 45-49
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Tidskriftsartikel (refereegranskat)abstract
- The increased use of silver as a biocide in nanoparticle formulations has heightened concern on possible environmental implications owing to its toxicity. There is however very little data on the concentration levels of silver in marine and freshwaters. Here. I report data on dissolved (<0.4 mu m filter) silver concentration in the surface waters of the Baltic Sea, the first such data reported for a European coastal water body. Levels of dissolved silver in the Baltic are comparable to those reported for other American estuarine waters and range from non-detectable in the open Baltic Sea Proper (<1 pM) to 9.4 pM (1 ng/L) in the Stockholm Archipelago, with a mean of 2.8 pM (0.2 ng/L). Inputs from wastewater treatment are clearly discernable and might constitute the main source of silver to the Stockholm Archipelago and possibly the Baltic Sea Proper.
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| 3. |
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| 4. |
- Ndung'u, Kuria, et al.
(författare)
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Lead isotopes reveal different sources of lead in balsamic and other vinegars
- 2011
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 409:14, s. 2754-2760
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Tidskriftsartikel (refereegranskat)abstract
- Fifty-eight brands of balsamic vinegars were analyzed for lead concentrations and isotopic compositions ((204)Pb, (206)Pb, (207)Pb, and (208)Pb) to test the findings of a previous study indicating relatively high levels of lead contamination in some of those vinegars more than two thirds (70%) of them exceeded California's State Maximum Level (34 mu g/L) based on consumption rates >= 0.5 mu g Pb per day. The Lead isotopic fingerprints of all those vinegars with high lead concentrations were then found to be primarily anthropogenic. This isotopic analysis unquestionably reveals multiple contamination sources including atmospheric pollutant Pb and an unidentified contamination source, likely occurring after grape harvest. Organically grown grape vinegars display the same Pb content and isotopic signatures as other vinegars. This implies that pesticides might not be a significant source of pollutant Pb in vinegars. A significant post-harvest contamination would be inherited from chemicals added during production and/or material used during transport, processing or storage of these vinegars. This is consistent with the highest Pb levels being found in aged vinegars (112 +/- 112 mu g/L) in contrast to other vinegars (41.6 +/- 28.9 mu g/L) suggesting contamination during storage. It is, therefore, projected that lead levels in most vinegars, especially aged balsamic and wine vinegars, will decrease with improvements in their manufacture and storage processes consequential to recent concerns of elevated levels of lead in some vinegars.
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| 5. |
- Ndung'u, Kuria
(författare)
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Liquid Membrane Techniques for Trace Metal Analysis and Speciation in Environmental and Biological Matrices
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, liquid-membrane-based methods for the analysis of trace metal species in samples of environmental and biological origin were developed. By incorporating extracting reagents in the membrane liquid, trace metal ions were selectively separated from humic-rich natural waters and urine samples, prior to their determination using various instrumental techniques. The extractions were performed in closed flow systems thus allowing easy automation of both the sample clean-up and enrichment. An acidic organophosphorus reagent (DEHPA) and a basic tetraalkylammonium reagent (Aliquat-336) were used as extractants in the membrane liquid to selectively extract and enrich cationic and anionic metal species respectively. A speciation method for chromium species was developed that allowed the determination of cationic Cr(III) species and anionic Cr(VI) species in natural water samples without the need of a chromatographic separation step prior to their detection. SLM was also coupled on-line to potentiometric stripping analysis providing a fast and sensitive method for analysis of Pb in urine samples. A microporous membrane liquid-liquid extraction (MMLLE) method was developed for the determination of organotin compounds in natural waters that reduced the number of manual steps involved in the LLE of organotin compounds prior to their GC separation. Clean extracts obtained after running unfiltered humic-rich river water samples through the MMLLE flow system allowed selective determination of all the organotin compounds in a single run using GC-MS in the selected ion monitoring mode (SIM).
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| 6. |
- Ndungu, Kuria
(författare)
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Model predictions of copper speciation in coastal water compared to measurements by analytical voltammetry
- 2012
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 46:14, s. 7644-7652
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Tidskriftsartikel (refereegranskat)abstract
- Trace metal toxicity to aquatic biota is highly dependent on the metals chemical speciation. Accordingly, metal speciation is being incorporated in to water quality criteria and toxicity regulations using the Biotic Ligand Model (BLM) but there are currently no BLM for biota in marine and estuarine waters. In this study, I compare copper speciation measurements in a typical coastal water made using Competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV) to model calculations using Visual MINTEQ, Both Visual MINTEQ and BLM use similar programs to model copper interactions with dissolved organic matter-DOM (i.e., the Stockholm Humic Model and WHAM-Windermere Humic Aqueous Model, respectively). The total dissolved (<0.4 mu m filter) copper concentration, [CUT] in the study sites ranged from <10 nM close to the open Baltic Sea to ca. 50 nM in the vicinity of a marina in the Stockholm Archipelago. The corresponding free copper concentration [Cu2+], measured by CLE-ACSV ranged from 10(-13.2) M to 10(-12.0) M for the reference and marina sites, respectively, whereas the corresponding [Cu2+] modeled calculations ranged from 10(-12.5) M to 10(-11.6) M. The low copper to DOM ratios (similar to 0.0004 mg Cu per mg DOC) in these coastal waters ensured that ambient dissolved copper was overwhelmingly chelated to strong Cu-binding ligands (12 < log K-cuL1,Cu2+(Cond) >14). The modeled [Cu2+] could be fitted to the experimental values better after the conditional stability constant for copper binding to fulvic acid (FA) complexes in DOM in the SHM was adjusted to account for higher concentration of strong Cu-binding sites in FA.
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| 7. |
- Papantoni, Margareta, et al.
(författare)
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Trace enrichment of metals using a supported liquid membrane technique
- 1995
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Ingår i: Analyst. - 0003-2654. ; 120:5, s. 1471-1477
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Tidskriftsartikel (refereegranskat)abstract
- The supported liquid membrane technique offers new possibilities for analytical enrichment, field sampling and speciation. The possibility of using the technique for the enrichment of metals in a flow system with off-line atomic absorption spectrometry in the final analysis step is outlined. Five metals (Cu, Cd, Co, Ni and Zn) have been used as model substances and different approaches to transport metals across the membrane are demonstrated. In one system 8-hydroxyquinoline was used as complexing agent in the sample (donor) solution. In a second system potassium thiocyanate was used in the donor solution and an extradant (Aliquat-336) in the membrane liquid. In a third system 8-hydroxyquinoline was used in the donor solution and Aliquat-336 in the membrane liquid. The parameters important for analytical enrichment are considered. These include factors for determining the extraction efficiency, the possibility of carry-over effects, matrix dependence and long-term membrane stability. The memory effects were below 2% and high concentrations of humic acids or salts did not interfere in the analysis. The long-term stability using di-n-hexyl ether in the membrane was 1-2 weeks and with the extractant Aliquat-336 incorporated in the membrane liquid it was 4 d. Determination of metals at levels <1 ppb was possible. The limiting factor for the determination at lower concentrations at present is the metal contamination in the reagents used.
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| 8. |
- Ruyle, Bridger J., et al.
(författare)
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Interlaboratory Comparison of Extractable Organofluorine Measurements in Groundwater and Eel (Anguilla rostrata) : Recommendations for Methods Standardization
- 2023
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 57:48, s. 20159-20168
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Tidskriftsartikel (refereegranskat)abstract
- Research on per- and polyfluoroalkyl substances (PFAS) frequently incorporates organofluorine measurements, particularly because they could support a class-based approach to regulation. However, standardized methods for organofluorine analysis in a broad suite of matrices are currently unavailable, including a method for extractable organofluorine (EOF) measured using combustion ion chromatography (CIC). Here, we report the results of an international interlaboratory comparison. Seven laboratories representing academia, government, and the private sector measured paired EOF and PFAS concentrations in groundwater and eel (Anguilla rostrata) from a site contaminated by aqueous film-forming foam. Among all laboratories, targeted PFAS could not explain all EOF in groundwater but accounted for most EOF in eel. EOF results from all laboratories for at least one replicate extract fell within one standard deviation of the interlaboratory mean for groundwater and five out of seven laboratories for eel. PFAS spike mixture recoveries for EOF measurements in groundwater and eel were close to the criterion (±30%) for standardized targeted PFAS methods. Instrumental operation of the CIC such as replicate sample injections was a major source of measurement uncertainty. Blank contamination and incomplete inorganic fluorine removal may introduce additional uncertainties. To elucidate the presence of unknown organofluorine using paired EOF and PFAS measurements, we recommend that analysts carefully consider confounding methodological uncertainties such as differences in precision between measurements, data processing steps such as blank subtraction and replicate analyses, and the relative recoveries of PFAS and other fluorine compounds.
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| 9. |
- Yager, P. L., et al.
(författare)
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ASPIRE The Amundsen Sea Polynya International Research Expedition
- 2012
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Ingår i: Oceanography. - : The Oceanography Society. - 1042-8275. ; 25:3, s. 40-53
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Tidskriftsartikel (refereegranskat)abstract
- In search of an explanation for some of the greenest waters ever seen in coastal Antarctica and their possible link to some of the fastest melting glaciers and declining summer sea ice, the Amundsen Sea Polynya International Research Expedition (ASPIRE) challenged the capabilities of the US Antarctic Program and RVIB Nathaniel B. Palmer during Austral summer 2010-2011. We were well rewarded by both an extraordinary research platform and a truly remarkable oceanic setting. Here we provide further insights into the key questions that motivated our sampling approach during ASPIRE and present some preliminary findings, while highlighting the value of the Palmer for accomplishing complex, multifaceted oceanographic research in such a challenging environment.
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| 10. |
- Ytreberg, Erik, et al.
(författare)
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Effect of Organic Complexation on Copper Accumulation and Toxicity to the Estuarine Red Macroalga Ceramium tenuicorne : A Test of the Free Ion Activity Model
- 2011
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 45:7, s. 3145-3153
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Tidskriftsartikel (refereegranskat)abstract
- Current water quality criteria (WQC) regulations on copper toxicity to biota are still based on total dissolved (<0.4 μm membrane filter) copper concentrations with a hardness modification for freshwaters. There are however ongoing efforts to incorporate metal speciation in WQC and toxicity regulations (such as the biotic ligand model-BLM) for copper and other metals. Here, we show that copper accumulation and growth inhibition of the Baltic macroalga Ceramium tenuicorne exposed to copper in artificial seawater at typical coastal and estuarine DOC concentrations (similar to 2−4 mg/L-C as fulvic acid) are better correlated to weakly complexed and total dissolved copper concentrations rather than the free copper concentration [Cu2+]. Our results using a combination of competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV) measurements and model calculations (using visual MINTEQ incorporating the Stockholm Humic Model) show that copper accumulation in C. tenuicorne only correlates linearly well to [Cu2+] at relatively high [Cu2+] and in the absence of fulvic acid. Thus the FIAM fails to describe copper accumulation in C. tenuicorne at copper and DOC concentrations typical of most marine waters. These results seem to indicate that at ambient total dissolved copper concentration in coastal and estuarine waters, C. tenuicorne might be able to access a sizable fraction of organically complexed copper when free copper concentration to the cell membrane is diffusion limited.
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| 11. |
- Ytreberg, Erik, et al.
(författare)
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Influence of salinity and organic matter on the toxicity of Cu to a brackish water and marine clone of the red macroalga Ceramium tenuicorne
- 2011
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Ingår i: Ecotoxicology and Environmental Safety. - : Elsevier BV. - 0147-6513 .- 1090-2414. ; 74:4, s. 636-642
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Tidskriftsartikel (refereegranskat)abstract
- Cu is a major active component in anti-fouling paints, which may reach toxic levels in areas with intense boat traffic and therefore is a metal of environmental concern. The bioavailability of metals is influenced by factors such as salinity and organic matter measured as total organic carbon (TOC). The influence of these two factors was studied, with a focus on brackish water conditions, by exposing a marine and a brackish water clone of the red macroalga Ceramium tenuicorne to Cu in different combinations of artificial seawater (salinity 5–15‰) and TOC (0–4 mg/L) in the form of fulvic acid (FA). In addition, the toxicity of Cu to both clones was compared in salinity 10‰ and 15‰. The results show that by increasing TOC from 0 to 2 and 4 mg/L, Cu was in general less toxic to both algal clones at all salinities tested (p<0.05). The effect of salinity on Cu toxicity was not as apparent, both a positive and negative effect was observed. The brackish water clone showed generally to be more sensitive to Cu in salinity 10‰ and 15‰ than the marine counterpart. In conclusion, FA reduced the Cu toxicity overall. The Cu tolerance of both strains at different salinities may reflect their origin and their adaptations to marine and brackish water.
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