The geology, hydrogeology, and groundwater geochemistry are described for an interface aquifer in Eastern Ontario exhibiting anomalously high proportions of iodine (I) as iodide (I-) and dissolved methane (CH4). The studied area is unique in that it shows a significant marine influence, attributed to the most recent Champlain Sea incursion 10 – 12 ka BP, which has implications for I and CH4 enrichment. I and CH4 in groundwater are found in high proportions in reducing fossil seawaters, which are typically observed in depressions in the bedrock surface that are overlain by thick layers of glaciomarine muds. I is released via microbial decomposition of marine phytoplankton into mud porewaters, where it is then leached to underlying groundwaters. 129I and 14C isotopic signatures of I and C compounds highlight the importance of allochthonous I and C sources in the Champlain Sea basin derived from glacial abrasion of the surrounding terrain and imported via glacial meltwater. CH4 is microbial in origin, with marine phytoplankton from the Champlain Sea incursion and ancient terrestrial organic matter from an Early Wisconsinian interstadial period (60 – 75 ka BP) as the dominant substrates. A thermogenic CH4 component was observed for areas underlain by the Billings shale unit. Both I and CH4 originate at least partially from the same marine phytoplankton source within the muds, demonstrate similar controls on enrichment, and have a Spearman’s rank coefficient of 0.62, indicating that the correlation between I and CH4 in groundwater in the studied area is significant.

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The ability to passivate metallic surfaces under non-UHV conditions is not only of fundamental interests, but also of growing practical importance in catalysis and microelectronics. In this work, the passivation effect of a surface iodine layer on air-exposed Ta for the copper electroless deposition was investigated by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Although the passivation effect was seriously weakened by the prolonged air exposure, iodine passivates the Ta substrate under brief air exposure conditions so that enhanced copper wetting and adhesion are observed on I-passivated Ta relative to the untreated surface.

Objectives: Molecular iodine released from povidone-iodine formulations significantly enhances periodontal probing depth reductions when applied into human periodontitis sites during mechanical root debridement, largely due to its antimicrobial activity against periodontal bacterial pathogens. Since molecular iodine accounts for the antimicrobial effects of povidone-iodine, new commercial mouthrinses with higher levels of free molecular iodine may also exert antimicrobial properties against periodontal bacterial pathogens. To evaluate this issue, the purpose of this study was to measure and compare the in vitro bactericidal effects of two molecular iodine-based mouthrinses against subgingival biofilm samples from adults with severe periodontitis, and against a fresh clinical subgingival isolate of the periodontal pathogen, Prevotella nigrescens. Methods: Paper point subgingival biofilm samples from 32 adults with severeperiodontitis, and a clinical subgingival isolate identified as P. nigrescens, were secondarily used in this study after their initial microbiological analysis at the Oral Microbiology Testing Service Laboratory at Temple University School of Dentistry. In a subgingival biofilm eradication assay, dilution aliquots from each subgingival biofilm specimen were mixed for a 60-second in vitro contact time with either Iorinse(R) RTU mouthrinse (containing 100 ppm molecular iodine) or iClean(R) mouthrinse (containing 150 ppm molecular iodine), and then neutralized with 3% sodium thiosulfate. The mixtures were then inoculated onto enriched Brucella blood agar culture plates, and incubated anaerobically for 7 days at 37 °C. Bacterial species growing subsequent to a 60-second mouthrinse contact time were considered to be resistant to that mouthrinse. Total viable counts in mouthrinse-exposed subgingival specimens were quantitated, and established phenotypic criteria employed to identify the following red/orange complex periodontal pathogens: Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia/nigrescens, Parvimonas micra, Campylobacter rectus, and Fusobacterium nucleatum group species. Subgingival sample dilution aliquots not exposed to the mouthrinses were similarly processed as controls for comparison with mouthrinse-exposed specimens, and were additionally inoculated onto enriched Brucella blood agar plates supplemented with either metronidazole at 16 mg/L, doxycycline at 4 mg/L, amoxicillin at 8 mg/L, or clindamycin at 4 mg/L, which represent recognized non-susceptible drug breakpoint concentrations for each of the antibiotics, followed by anaerobic incubation for 7 days at 37 ºC. In vitro antibiotic resistance was noted when any of the evaluated red/orange complex periodontal pathogens displayed growth on one or more of the antibiotic supplemented enriched Brucella blood agar plates. Nonparametric Wilcoxon signed-rank test analysis compared mean total subgingival viable counts, and mean total subgingival counts of the evaluated red/orange complex periodontal pathogens per patient, between subgingival biofilm samples exposed and not exposed in vitro to the molecular iodine mouthrinses, with a P-value of < 0.05 required for statistical significance. For in vitro susceptibility testing of the P. nigrescens subgingival isolate, aliquots of a 0.5 McFarland standard P. nigrescens cell suspension were mixed with each of the two molecular iodine mouthrinses, as well as with 10% and 0.1% solutions of povidone-iodine, and neutralized with sodium thiosulfate after a 60-second in vitro contact time. The mixtures were then plated onto enriched Brucella blood agar culture plates, and incubated in an anaerobic atmosphere for 7 days at 37 ºC, with total viable P. nigrescens counts on test solution-exposed plates compared to counts non-exposed P. nigrescens control plates. Results: Subgingival biofilms exposed in vitro to either the Iorinse(R) RTU oriClean(R) mouthrinses yielded significantly lower average total subgingival viable counts per patient, with reductions of 27.0% and 63.8%, respectively, than non-exposed control specimens (P < 0.0001). Similarly, both mouthrinses significantly reduced mean red/orange complex periodontal pathogen counts/patient by 74.4% and 97.4%, respectively, as compared to non-exposed control specimens (P < 0.0001). The iClean(R) mouthrinse better reduced average total subgingival viable counts and red/orange complex periodontal pathogen counts than the Iorinse(R) RTU mouthrinse (P-values < 0.0002 and < 0.0044, respectively). All evaluated red/orange complex periodontal pathogens were suppressed below detection by the Iorinse(R) RTU mouthrinse in 17 (53.1%) patient samples, and by the iClean(R) mouthrinse in 29 (90.6%) patient samples. Subgingival species resistant in vitro to the Iorinse(R) RTU mouthrinse were P. intermedia/nigrescens (8 of 25 patient strains), P. micra (7 of 32 patient strains), and F. nucleatum (6 of 30 patient strains), whereas species resistant to the iClean(R) mouthrinse were P. intermedia/nigrescens (1 of 25 patient strains), P. micra (2 of 32 patient strains), and F. nucleatum (2 of 30 patient strains). Relative to a clinical subgingival isolate of P. nigrescens, the Iorinse(R) RTU mouthrinse produced an 85% reduction, with the iClean(R) mouthrinse and both povidone-iodine concentrations (10% and 0.1%) attaining 100% reductions in total viable cell counts of P. nigrescens after 60 seconds of in vitro exposure. Conclusions: The Iorinse(R) RTU or iClean(R) mouthrinses both exhibited rapid invitro antimicrobial activity against human subgingival biofilm microorganisms, inducing 27.0% to 63.8% reductions, respectively, in total subgingival viable counts, and 74.4% to 97.4% reductions, respectively, in red/orange periodontal pathogen counts. The iClean(R) mouthrinse provided significantly better antimicrobial activity against subgingival biofilm bacteria in vitro than the Iorinse(R) RTU mouthrinse. These findings suggest merit in the clinical use of both molecular iodine-based mouthrinses in the treatment and prevention of bacterial biofilm-related human periodontal diseases.

Iodine, a minor constituent in ground water, is valuable as an indicator of subsurface sources of salinity. A review of iodine geochemistry reveals that exceptions to conservative behavior include sorption onto iron and aluminum oxides and incorporation into marine organic matter with additional enrichment due to sorption. Data from the Milk River aquifer in Alberta, Canada indicate that iodide in the ground water is derived from residual waters in the fine grained, marine sediments within the sandstone formation. This localized enrichment of iodide is superimposed on a more general enrichment of halides downgradient from the recharge area, probably due to ion filtration.

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