The groundwater-derived nutrient flux to estuaries and the coastal ocean can rival that of surface water inputs due to high groundwater nutrient concentrations. Groundwater inputs thus have an important impact on coastal water quality. Understanding patterns of variability in groundwater nutrient fluxes and the mechanisms generating this variability will help to inform coastal water resource management decisions. A suite of groundwater geochemical constituents has been monitored over the course of at least one year at two sites in coastal Georgia.

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

Exposure to progressive inputs of anthropogenic N deposition elicits a series of changes in terrestrial ecosystems associated with both enhancement and inhibition of biogeochemical processes. Initially, growth of plants is enhanced as the constraint of N supply on NPP is relaxed, sometimes associated with altered dominance of species and gains or losses in diversity. Higher rates of nitrification and leaching of base cations eventually lead to acidification of soils, increases in soluble aluminum, and potentially to decreases in rates of NPP.

Aquatic systems in urban areas may receive enhanced nutrient inputs from the surrounding landscape. The landscape structure within watersheds is hypothesized to influence nitrogen flux into aquatic systems. In urban areas, impervious surfaces and vegetation may be the structural elements which control these inputs. It has been hypothesized that increased impervious surface cover increases discharge to urban streams, which may be correlated with increased nitrogen flux. On the other hand, vegetation slows water flow and retains nutrients on the landscape.

In the McMurdo Dry Valleys of Antarctica, glaciers are hydrologically linked to closed-basin lakes at the valley floor by glacial melt water streams. We propose that the dynamics of meltwater generation and sub-stream thaw depth control the potential for the hyporheic zone and benthic communities to influence transport of nutrients and dissolved ions downstream. Little is known about the temporal variability of nutrient fluxes to the Dry Valley lakes.

The Detritus Inputs and Removal Treatments (DIRT) were established at the H.J. Andrews Experimental Forest to examine the effects of organic matter manipulations on soil organic matter (SOM) chemistry and nutrient cycling. In 2007, after ten years of manipulations, isotope dilution methods were used to estimate gross N mineralization and nitrification rates among the six treatments that control the rate and quality of SOM inputs (control, double wood, double litter, no roots, no litter, and no inputs).

Accelerating demand for liquid fuel, together with concerns about anthropogenic influence on the environment and fossil fuels availability, resulted in an increasing interest in using renewable energy sources, which could be grown agriculturally. However, increasing demand for food and acceleration of land-use change have raised concerns about use of food-based bio-fuel (i.e. corn ethanol) and turned research to the direction of cellulosic feedstocks.

Phosphorus (P) is often limiting in aquatic ecosystems. The quantity of available P is often determined by sediment binding and release processes. We obtained 32 sediment samples from shallow freshwater ecosystems in Southwest Michigan. Sediment cores were separated into consolidated and flocculent strata for analysis of percent organic matter, total sediment phosphorus (TP), and HCl-extractable iron (HCl~Fe). Sediment TP ranged from 110-3348 ugP/gdw, with an average of 1052 ugP/gdw.