Turkey Lakes Watershed Study reference list: 2009

09-01  Zhang, L., R. Vet, J.M. O’Brien, C. Mihele, Z. Liang, and A. Wiebe.  Dry deposition of individual nitrogen species at eight Canadian rural sites.  J. Geophys. Res. 114, D02301, 13pp, 2009.

Summary: The TLW was one of eight rural sites sampled between 2001 and 2005 to study the relative contribution of nitrogen species to total dry and dry + wet nitrogen deposition. Air concentrations for oxidized nitrogen (NOy) and major species comprising NOy, and the two reduced species (NH₃, pNH4⁺) were monitored for this period. It was found that the contribution of non-routinely measured nitrogen species is significant and contributes up to 50% of total nitrogen dry deposition. Current estimates of atmospheric nitrogen deposition can be improved by adding measurements for NO₂ and NH₃ to the air quality models.

09-02 Snider, D.M., S.L. Schiff, J. Spoelstra*. ¹⁵N/¹⁴N and ¹⁸O/¹⁶O stable isotope ratios of nitrous oxide produced during denitrification in temperate forest soils.  Geochim. Cosmochim. Acta 73, 877-888, 2009. (* Author of correspondence).

Summary: Soils from upland and wetland sites at the TLW were incubated at different moisture and temperature conditions.  N₂O production increased with higher temperatures and soil moistures in all soils, and the rate of production was greater in the wetland soils.  The oxygen isotope fractionation was complicated by exchange with water, and quantifying the ¹⁸O/¹⁶O ratios of N₂O may be useful for characterizing the microbial community in soils.

09-03  Muir*, D.C.G., X. Wang, F. Yang, N. Nguyen, T.A. Jackson, M.S. Evans, M. Douglas, G. Köck, S. Lamoureux, R. Pienitz, J.P. Smol, W.F. Vincent, A. Dastoor.  Spatial trends and historical deposition of mercury in eastern and northern Canada inferred from lake sediment cores.  Environ. Sci. Technol., 43, 4802-4809, 2009. (*Contact D.S. Jeffries for correspondence).

Summary: Batchawana Lake was classed as a mid-latitude lake in a survey of spatial trends and historical deposition of mercury conducted during 1998-2005.  Dated lake sediment cores from 50 lakes in eastern and northern Canada were collected and analyzed, and increases in mercury deposition over time were observed in all the midlatitude cores.  The observed trends support the view that there are significant anthropogenic mercury inputs into the Arctic.

09-04 Murphy*, P.N.C., M. Castonguay, J. Ogilvie, M. Nasr, P. Hazlett, J. Bhatti and P.A. Arp.  A geospatial and temporal framework for modeling gaseous N and other N losses from forest soils and basins, with application to the Turkey Lakes Watershed Project, in Ontario, Canada.  For. Ecol. Manage. 258, 2304-2317, 2009. (*Contact D.S. Jeffries for correspondence).

Summary: A digital elevation, hydrological modeling approach is applied to the TLW soils and basins to quantify the pre- and post-harvest N emissions and other N losses.  The calibrated model suggests that nitrification and denitrification induced by harvesting are strongest during the first post-harvest year but drop to background levels in 4-5 years.  Further studies are needed to determine whether increased N input due to harvesting leads to N immobilization in mineral soils.

09-05  Creed, I.F. and F.D. Beall.  Distributed topographic indicators for predicting nitrogen export from headwater catchments.  Wat. Resourc. Res. 45, W10407, 12pp, 2009. (*Author of correspondence).

Summary: With the objective of determining whether topographic indicators can be used as a means to predict spatial variation in dissolved N export from watersheds, data from the spring melt at the TLW were employed in a conceptual model of hydrologic flushing of dissolved N.  Distributed topographic indicators proved to be good predictors of the majority of variation in N export, and thus may be useful in extrapolating variances in unmonitored watersheds.

09-06  Webster, K.L., I.F. Creed, M.D. Skowronski and Y.H. Kaheil. Comparison of the performance of statistical models that predict soil respiration from forests. Soil Science Society of America Journal 73 (4), 1157-1167, doi:10.2136/sssaj2008.0310, 2009.

Summary: Numerous statistical models have been developed to explain Rs as a function of physical and chemical conditions, but the performance of these models has not been adequately evaluated. Soils in the TLW were monitored for Rs and its physical and chemical drivers, and the data was used to fit statistical models and compare their performance. An exponential model in which the exponent is a polynomial expression, linear with respect to temperature and quadratic with respect to soil moisture explained 57% of the variance in Rs, and was improved to 71% following the inclusion of C quantity and substrate quality of the soils. These findings support the identification of Rs controls within an ecosystem in order to assess the generality of these controls on Rs across ecosystems using statistical models and analysis.