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  • 1
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    Rapid, At-Sea Detection of Munition Compounds in Coastal Waters Using a Shipboard System (2023)
    ACS (American Chemical Society)
    Details
    Publication Date: 2024-02-29
    Description: Coastal waters are contaminated globally with millions of metric tons of munitions from the two world wars which constitute a potential threat to ecosystems and humans. Laboratory-based chemical methods for the detection of munition compounds (MCs) in seawater typically take weeks to months between sample collection and analysis. The current work details a novel, field-deployable system for rapid (under 10 min) analysis of four common MCs (1,3-dinitrobenzene (DNB), amino-4,6-dinitrotoluene (ADNT), 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX)). The system uses a fluidic preconcentration unit with high-performance liquid chromatography (HPLC) and detection by electrospray-ionization mass spectrometry and UV–vis spectroscopy. The fluidic unit comprises two solid-phase extraction (SPE) columns for preconcentration of target MCs from the seawater matrix and allows loading and analysis of two samples simultaneously. Seven SPE resins were tested for extraction efficiency and robustness, with Porapak RDX showing best performance. Chromatographic separation of target MCs was performed using a C8 reversed-phase HPLC column. Limits of detection (LODs) were 3.7, 1.8, 3.6, and 10.7 ng L–1 for DNB, ADNT, TNT, and RDX, respectively. The system’s analytical performance and automated data processing procedure were demonstrated in the Baltic Sea.
    Type: Article , PeerReviewed
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    In situ measurements of explosive compound dissolution fluxes from exposed munition material in the Baltic Sea (2019)
    ACS (American Chemical Society)
    In:  Environmental Science & Technology, 53 (10). pp. 5652-5660.
    Details
    Publication Date: 2022-01-31
    Description: Underwater munitions containing millions of tons of toxic explosives are present worldwide in coastal marine waters as a result of unexploded ordnance and intentional dumping. Dissolution flux of solid explosives following corrosion of metal munition housings controls exposure of biological receptors to toxic munition compounds (MC; including TNT: 2,4,6-Trinitrotoluene, RDX: 1,3,5-Trinitro-1,3,5-triazinane, and DNB: 1,3-Dinitrobenzene). Very little is known about the dissolution behavior of MC in the marine environment. In this work, we exploit a unique marine study site in the Baltic Sea with exposed solid explosives to quantify in situ MC dissolution fluxes using dissolved MC gradients near the exposed explosive surface, as well as benthic chamber incubations. The gradient method gave dissolution fluxes that ranged between 0.001 and 3.2, 0.0001 and 0.04, and 0.003 and 1.7 mg cm-2 d-1 for TNT, RDX, and DNB, respectively. Benthic chamber incubations indicated dissolution fluxes of 0.0047-0.277, 0-0.11, and 0.00047-1.45 mg cm-2 d-1 for TNT, RDX, and DNB, respectively. In situ dissolution fluxes estimated in the current study were lower than most dissolution rates reported for laboratory experiments, but clearly demonstrated that MC are released from underwater munitions to the water column in the Baltic Sea.
    Type: Article , PeerReviewed
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    DOI: 10.1021/acs.est.8b06974
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Seasonal Variations in Proton Binding Characteristics of Dissolved Organic Matter Isolated from the Southwest Baltic Sea (2021)
    ACS (American Chemical Society)
    Details
    Publication Date: 2024-02-07
    Description: The physicochemical characteristics of dissolved organic matter (DOM) strongly influence its interactions with inorganic species such as protons and trace elements in natural waters. We collected water samples at Boknis Eck, a time series station in the Baltic Sea with a low exposure to freshwater inputs, to investigate how seasonal fluctuations impact the proton binding properties of the isolated DOM. We used potentiometric titrations to assess the binding properties of solid-phase extracted DOM (SPE–DOM) over a seasonal cycle. We report and critically analyze the first NICA parameters estimates of carboxylic-like and phenolic-like sites for brackish water SPE–DOM. The total amount of functional groups (QmaxH,tot) showed no seasonal fluctuations and an average value of 136 ± 5.2 mmol·mol C–1. The average proton affinity (logKH) and binding site heterogeneity (m) showed a relatively minor variability for samples obtained between April and September, when the water remained stratified. These results contribute to a better understanding of the ion binding characteristics of DOM in natural brackish waters.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: archive
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Influence of pH and Dissolved Organic Matter on Iron Speciation and Apparent Iron Solubility in the Peruvian Shelf and Slope Region (2021)
    ACS (American Chemical Society)
    Details
    Publication Date: 2024-02-07
    Description: The chemical speciation of iron (Fe) in oceans is influenced by ambient pH, dissolved oxygen, and the concentrations and strengths of the binding sites of dissolved organic matter (DOM). Here, we derived new nonideal competitive adsorption (NICA) constants for Fe(III) binding to marine DOM via pH-Fe titrations. We used the constants to calculate Fe(III) speciation and derive the apparent Fe(III) solubility (SFe(III)app) in the ambient water column across the Peruvian shelf and slope region. We define SFe(III)app as the sum of aqueous inorganic Fe(III) species and Fe(III) bound to DOM at a free Fe (Fe3+) concentration equal to the limiting solubility of Fe hydroxide (Fe(OH)3(s)). A ca. twofold increase in SFe(III)app in the oxygen minimum zone (OMZ) compared to surface waters is predicted. The increase results from a one order of magnitude decrease in H+ concentration which impacts both Fe(III) hydroxide solubility and organic complexation. A correlation matrix suggests that changes in pH have a larger impact on SFe(III)app and Fe(III) speciation than DOM in this region. Using Fe(II) measurements, we calculated ambient DFe(III) and compared the value with the predicted SFe(III)app. The underlying distribution of ambient DFe(III) largely reflected the predicted SFe(III)app, indicating that decreased pH as a result of OMZ intensification and ocean acidification may increase SFe(III)app with potential impacts on surface DFe inventories.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Proton Binding Characteristics of Dissolved Organic Matter Extracted from the North Atlantic (2023)
    ACS (American Chemical Society)
    Details
    Publication Date: 2024-02-07
    Description: Marine dissolved organic matter (DOM) presents key thermodynamic properties that are not yet fully constrained. Here, we report the distribution of binding sites occupied by protons (i.e., proton affinity spectra) and parametrize the median intrinsic proton binding affinities (log K̅H) and heterogeneities (m), for DOM samples extracted from the North Atlantic. We estimate that 11.4 ± 0.6% of C atoms in the extracted marine DOM have a functional group with a binding site for ionic species. The log K̅H of the most acidic groups was larger (4.01–4.02 ± 0.02) than that observed in DOM from coastal waters (3.82 ± 0.02), while the chemical binding heterogeneity parameter increased with depth to values (m1= 0.666 ± 0.009) ca. 10% higher than those observed in surface open ocean or coastal samples. On the contrary, the log K̅H for the less acidic groups shows a difference between the surface (10.01 ± 0.08) and deep (9.22 ± 0.35) samples. The latter chemical groups were more heterogeneous for marine than for terrestrial DOM, and m2 decreased with depth to values of 0.28 ± 0.03. Binding heterogeneity reflects aromatic carbon compounds’ persistence and accumulation in diverse, low-abundance chemical forms, while easily degradable low-affinity groups accumulate more uniformly in the deep ocean.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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