Geophysical and Hydrological Evaluation of Two Bog Complexes in a Northern Peatland: Implications for the Distribution of Biogenic Gases at the Basin Scale

Ground penetrating radar (GPR) was used to determine peat basin geometry and the spatial distribution of free-phase biogenic gasses in two separate units of a northern peatland (Central and Southern Unit of Caribou Bog, Maine). The Central Unit is characterized by a deep basin structure (15 m maximum depth) and a raised (eccentric) bog topographic profile (up to 2 m topographic variation). Here numerous regions of electromagnetic (EM) wave scattering are considered diagnostic of the presence of extensive free-phase biogenic gas. In contrast, the Southern Unit is shallower (8 m maximum depth) and has a slightly convex upwards bog profile (less than 1 m topographic variation), and areas of EM wave scattering are notably absent. The biogenic gas zones interpreted from GPR in the Central Unit are associated with: (1) wooded heath vegetation at the surface, (2) open pools at the surface, (3) high water table elevations near the center of the basin, and (4) a region of overpressure (at approximately 5 m depth) immediately below the zone of free-phase gas accumulation. The latter suggests (1) a transient pressure head associated with low hydraulic conductivity resulting from the biogenic gasses themselves or confining layers in the peat that restrict both gas release and groundwater flow and/or (2) overpressure in the peat column as a result of the gas buildup itself. In contrast, the Southern Unit, where zones of EM scattering are absent, is characterized by: (1) predominantly shrub vegetation, (2) a lack of open pools, (3) only minor variations (less than 1 m) in water table elevation throughout the entire unit; and (4) generally upward groundwater flow throughout the basin. The results illustrate the nonuniformity of free-phase biogenic gas distribution at the peat basin scale and provide insights into the processes and controls associated with CH4 and CO2 accumulation in peatlands.

Phonological Translation in Bilingual and Monolingual Children

Bilingual children face a variety of challenges that their monolingual peers do not. For instance, switching between languages requires the phonological translation of proper names, a skill that requires mapping the phonemic units of one language onto the phonemic units of the other. Proficiency of phonological awareness has been linked to reading success, but little information is available about phonological awareness across multiple phonologies. Furthermore, the relationship between this kind of phonological awareness and reading has never been addressed. The current study investigated phonological translation using a task designed to measure children's ability to map one phonological system onto another. A total of 425 kindergarten and second grade monolingual and bilingual students were evaluated. The results suggest that monolinguals generally performed poorly. Bilinguals translated real names more accurately than fictitious names, in both directions. Correlations between phonological translation and measures of reading ability were moderate, but reliable. Phonological translation is proposed as a tool with which to evaluate phonological awareness through the perspective of children who live with two languages and two attendant phonemic systems.