The goal of the Arctic LTER is to predict the future ecological characteristics of Arctic Alaska based upon our knowledge of the controls of ecosystem structure and function as exerted by physical setting and geologic factors, climatic factors, biotic factors, and the changes in fluxes of water and materials from land to water.

 Biogeochemical fluxes through urban residences contribute significantly to the overall biogeochemical cycles of cities and of the nation. However, little is known about how biogeochemical fluxes that contribute to environmental pollution vary among households, nor what factors contribute to that variation. We quantified the fluxes of carbon (C), nitrogen (N), and phosphorus (P) through households along an urban to exurban gradient in the Saint Paul-Minneapolis, Minnesota metropolitan area.

Dissolved organic matter (DOM) dominates the material and energy fluxes within aquatic ecosystems. Carbon fuels the majority of microbial processes, including those that regulate in-stream nitrogen constituents. DOM sources and in situ transformations determine its chemical nature and lability within aquatic systems. Boulder Creek, which is located in the Colorado Front Range and spans an ecosystem gradient from the Continental Divide to the high plains, receives excess atmospheric nitrogen deposition due to its proximity to population centers and agricultural lands.

Despite substantial changes in climate, sea-ice and glacier extent, and vegetation in much of the Arctic, the area near Toolik Lake, Alaska has experienced no significant trends of increasing temperature, altered precipitation, or increasing active-layer thaw depth. There has been, however, a near doubling of alkalinity in Toolik Lake since 1975 and increases in alkalinity in many lakes of all depths and sizes in the surrounding area. Lake monitoring indicates that in-lake processes such as sulfate or nitrate reduction cannot account for these alkalinity increases.

Imprecise, inaccurate, and inconsistent soil sampling techniques are a major source of uncertainty in the calculation of nutrient budgets. Traditional methods of soil sampling include soil coring and excavation of quantitative soil pits. The major problem encountered with soil coring is that rocky soils limit the location and depth of sampling, and therefore the soil volume is not accurately measured. Quantitative soil pits resolve the rock volume bias, but they are notoriously laborious and destructive, making repeated measurements difficult in spatially variable sites.

Iron (Fe) is abundant among trace elements in forest ecosystems and important in the development and function of soils. We constructed a biogeochemical budget for Fe to better understand the behavior of Fe and its role in the development of Spodosols (podsolization). Fluxes of reduced (ferrous, Fe(II)) and oxidized (ferric, Fe(III)) iron draining through the soil profile were calculated.

Many ecosystems, including grassland, forest, alpine, and desert, have shown responses to N enrichment. These responses vary considerably but include changes in soil respiration rates, enzyme activities, and microbial community structure. Surprisingly, little work has examined the effects of N enrichment on soil communities and processes in agricultural systems despite the high rates of N applied in most crop production systems.

Relatively little attention has been given to the processes that control the production and subsequent availability of amino acids in temperate forest soils. We examined how differences in soil organic matter chemistry and mycorrhizal association between temperate forest tree species of the Northeastern US lead to variation in amino acid cycling. We measured amino acid cycling throughout the growing season in soils from single tree species plots located in both the Harvard Forest, MA and the Pisgah State Forest, NH.

Reach scale experiments have shown that transient storage (TS) zones may be important controls on dissolved inorganic nitrogen (DIN) export to coastal waters. Here, we investigated the relative impact that main channel (MC), surface TS (STS) and hyporheic TS (HTS) have on DIN removal at the network scale using a DIN removal model applied to the Ipswich River in Massachusetts, USA.

With recent shifts in public attitudes across the United States concerning the problem of global climate change, momentum is building for aggressive action to mitigate greenhouse gas emissions. At the same time, the ongoing economic recession presents challenges for financing an aggressive climate change abatement campaign; hence, it is imperative that cost-effective strategies for reducing greenhouse gas emissions be identified and pursued. To accomplish this, policy instruments will need to be tailored to a complex range of local and regional conditions.