COS 166-2 - The role of nanoparticles and low molecular weight organic acids in the development of a northern forest soil

Background/Question/Methods

In the Northeast, fossil fuel combustion resulted in acid rain which impacted soils by accelerating leaching of minerals and nutrients. Moreover, carbon dioxide fertilization and changing climate are impacting carbon cycling and dynamics in forest ecosystems. Over the past sixty years, researchers have monitored watersheds at Hubbard Brook Experimental Forest in New Hampshire USA to analyze element fluxes and cycling. In 1999, wollastonite (CaSiO₃) was added to Watershed 1 to experimentally replace the calcium lost due to acid rain. The objective of this study is to: 1) compare patterns in dissolved organic carbon (DOC) and nitrogen (DN) of the treated Watershed 1 with reference, Watershed 6; 2) quantify organic acids present in the soil solutions; and 3) investigate the transport of organic acids through different soil horizons. Dissolved organic matter (DOM) serves as an indicator of watershed carbon cycling, links terrestrial to aquatic ecosystems, and provides an energy source to microbes. There have been various studies showing qualitative data of dissolved organic matter (DOM). In this presentation we couple qualitative data obtained using fluorescence spectroscopy coupled with parallel factor analysis (PARAFAC) with a quantitative determination of low molecular weight organic acids using ion chromatography.

Results/Conclusions

Preliminary results revealed there is a decreasing pattern in concentrations of organic acids as they infiltrate from the upper (Oa) to the lower soil horizons (Bh, and Bs). This pattern was supported by statistically higher DOC & DON and oxalate concentrations in the calcium-treated organic (Oa) soil solutions. Future work will include measuring particle sizes of soil solutions and determining variation in soil solution patterns by watershed elevation and season.