Showing papers by "Danielle Fortin published in 2011"
TL;DR: The inhibition of both methanogens and SRB was found to enhance the iron reduction rates but did not completely stop MMHg production, indicating that iron reduction may influence net methylation in the SLR sediments by decreasing demethylation rather than favouring methylation.
99 citations
TL;DR: It is shown that anammox performing organisms were abundant bacterial community members at three ammonium-contaminated groundwater sites, providing strong evidence for their important biogeochemical role in attenuating groundwater ammonium contamination.
Abstract: Anaerobic ammonium-oxidizing (anammox) bacteria perform an important step in the global nitrogen cycle: anaerobic oxidation of ammonium and reduction of nitrite to form dinitrogen gas (N(2)). Anammox organisms appear to be widely distributed in natural and artificial environments. However, their roles in groundwater ammonium attenuation remain unclear and only limited biomarker-based data confirmed their presence prior to this study. We used complementary molecular and isotope-based methods to assess anammox diversity and activity occurring at three ammonium-contaminated groundwater sites: quantitative PCR, denaturing gradient gel electrophoresis, sequencing of 16S rRNA genes, and (15)N-tracer incubations. Here we show that anammox performing organisms were abundant bacterial community members. Although all sites were dominated by Candidatus Brocadia-like sequences, the community at one site was particularly diverse, possessing four of five known genera of anammox bacteria. Isotope data showed that anammox produced up to 18 and 36% of N(2) at these sites. By combining molecular and isotopic results we have demonstrated the diversity, abundance, and activity of these autotrophic bacteria. Our results provide strong evidence for their important biogeochemical role in attenuating groundwater ammonium contamination.
94 citations
TL;DR: In this article, the ability of wetland bacteriogenic iron oxides (BIOS) to immobilize iodide in contaminated groundwater systems near Chalk River, Canada was investigated using an autotitrator and an I− ion-selective electrode to generate high-resolution anion sorption data over a pH range of 2.5 to 9.5.
Abstract: This study was performed to determine the ability of wetland bacteriogenic iron oxides (BIOS) to immobilize iodide in contaminated groundwater systems near Chalk River, Canada. The sorption of iodide onto synthetic hydrous ferric oxide (HFO) and BIOS was investigated using an autotitrator and an I− ion-selective electrode to generate high-resolution anion sorption data over a pH range of 2.5 to 9. The effect of strontium sorption in the presence of I− was also investigated to determine its effect on iodide retention as it is also a common contaminant near Chalk River. Both HFO and BIOS correspond to 2-line ferrihydrite with surface areas of 227.7 m2 g−1 and 92.52 m2 g−1, respectively. Sorption of I− was found to be pH dependent for both HFO and BIOS and was most strongly immobilized at pH 2.5. The pH at which 50% of the I− was bound to HFO occurred at pH 4.0, whereas BIOS maintained 50% sorption to pH 9. Field data also indicated a 54% decrease for iodine and 75% for 129I in waters passing over in-situ BI...
35 citations
TL;DR: Takahashi et al. as mentioned in this paper investigated the role of rare earth elements on bacterial cell walls and its implication for REE sorption onto natural microbial mats, and showed that the rare earth element can be used for bacterial cell wall adaption.
1 citations