Movement of Inorganic Matter
The propagating response of inner shelf circulation to wind relaxations along the central California Coast
Following relaxations prevailing equatorward winds, warm water from the Santa Barbara Channel flows poleward around Point Conception and along the central California coast. Sequences of satellite sea surface temperature images show the events as bands of warm water extending up to 20 km offshore. Characteristics of these flows were examined using time series of currents and temperature from an array of moorings along the inner shelf (15 m depth), a mooring on the mid-shelf (100 m depth), and surface current observations from high frequency radars.
Recent 15N tracing studies have highlighted the important role biotic assimilation plays in stream N retention, yet the fate of N following assimilation is not well understood. One potentially important fate is indirect denitrification, a process in which locally mineralized and nitrified N is denitrified before being exported to the water column. We conducted a series of in-situ chamber experiments in which patches of stream bottom were labeled with 15N to investigate the fate of assimilated N.
The Niwot Ridge (NWT) LTER site was one of the five original LTER sites established in 1980. The LTER program is based at the University of Colorado-Boulder and is administered through the Institute of Arctic and Alpine Research (INSTAAR) and in cooperation with the Mountain Research Station, with special use permits from the US Forest Service.
Seasonal and spatial heterotrophic bacterial dynamics and phosphorus uptake and regeneration in Lake Mendota, WI
Bacteria community dynamics and metabolism are relevant to understanding the mechanism of phosphorus cycling in eutrophic lake systems. In Lake Mendota, WI, heterotrophic bacterial abundance as measured by catalyzed reporter deposition fluorescence in situ hybridization (CARD FISH), 33PO4-3 uptake and regeneration, 14C- leucine incorporation, alkaline phosphatase activity, and a suite of chemical analysis were measured during 2009 ice-off period in order to identify seasonal and spatial trends.
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.
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.
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.
Consequences of increased N input in highly acid conditions of Western Tatra Mts. (Slovakia, Europe)
The experimental research in Salatín (Western Tatra Mts., Slovakia) address the impact of nitrogen (N) deposition on ecosystem of alpine grasslands. The site was exposed during last 50 years to high acid deposition with maximum rates of wet deposition at least 15–20 kg N ha-1 yr-1 and 20–25 kg S ha-1 yr-1. The experiment consists of 5 replicated treatments: 20, 60, and 150 Kg N ha-1 yr-1, 50 Kg P ha-1 yr-1 and the control, 25 plots in total.
Separation of river network scale nitrogen removal between surface and hyporheic transient storage compartments
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.