NLOAD : an interactive, web-based modeling tool for nitrogen management in estuaries

Author Posting. © Ecological Society of America, 2007. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Applications 17, Supple. (2007): S17–S30, doi:10.1890/05-1460.1.Eutrophication of estuaries is an increasing global concern that requires development of new tools to identify causes, quantify conditions, and propose management options that address this environmental problem. Since eutrophication is often associated with increased inputs of land-derived nitrogen to estuaries, we developed NLOAD, a user-friendly, web-based tool that brings together six different published models that predict nitrogen loading to estuaries and two models that estimate nitrogen concentrations in coastal waters. Here we describe each of the models, demonstrate how NLOAD is designed to function, and then use the models in NLOAD to predict nitrogen loads to Barnegat Bay, New Jersey (USA). The four models that we used to estimate nitrogen loads to Barnegat Bay, when adjusted, all had similar results that matched well with measured values and indicated that Barnegat Bay receives roughly 26 kg N·ha−1·yr−1. Atmospheric deposition was the dominant source of nitrogen to Barnegat Bay, followed by fertilizer nitrogen. Wastewater in Barnegat Bay is diverted to an offshore outfall and contributes no nitrogen to the system. The NLOAD tool has an additional feature that allows managers to assess the effectiveness of a variety of management options to reduce nitrogen loads. We demonstrate this feature of NLOAD through simulations in which fertilizer inputs to the Barnegat Bay watershed are reduced. Even modest cutbacks in the use of fertilizers on agricultural fields and lawns can be shown to reduce the amount of N entering Barnegat Bay.Support for the NLOAD tool came from the Cooperative Institute for Coastal and Estuarine Environmental Technologies (CICEET, CICEET-UNH grants #02-610 and #04-833). Additional funding was received from Environmental Defense

Barnegat Bay-Little Egg Harbor Estuary : case study of a highly eutrophic coastal bay system

Author Posting. © The Author(s), 2007. This is the author's version of the work. It is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Applications 17 (2007): S3–S16, doi:10.1890/05-0800.1.The Barnegat Bay-Little Egg Harbor Estuary is classified here as a highly eutrophic estuary based on application of NOAA’s National Estuarine Eutrophication Assessment model. Because it is shallow, poorly flushed, and bordered by highly developed watershed areas, the estuary is particularly susceptible to the effects of nutrient loading. Most of this load (~50%) is from surface water inflow, but substantial fractions also originate from atmospheric deposition (~39%), and direct groundwater discharges (~11%). No point source inputs of nutrients exist in the Barnegat Bay watershed. Since 1980, all treated wastewater from the Ocean County Utilities Authority's regional wastewater treatment system has been discharged 1.6 km offshore in the Atlantic Ocean. Eutrophy causes problems in this system, including excessive micro- and macroalgal growth, harmful algal blooms (HABs), altered benthic invertebrate communities, impacted harvestable fisheries, and loss of essential habitat (i.e., seagrass and shellfish beds). Similar problems are evident in other shallow lagoonal estuaries of the Mid-Atlantic and South Atlantic regions. To effectively address nutrient enrichment problems in the Barnegat Bay-Little Egg Harbor Estuary, it is important to determine the nutrient loading levels that produce observable impacts in the system. It is also vital to continually monitor and assess priority indicators of water quality change and estuarine health. In addition, the application of a new generation of innovative models using web-based tools (e.g., NLOAD) will enable researchers and decision-makers to more successfully manage nutrient loads from the watershed. Finally, the implementation of stormwater retrofit projects should have beneficial effects on the system.Financial support of the Barnegat Bay National Estuary Program and Jacques Cousteau National Estuarine Research Reserve is gratefully acknowledged

Mikromekaaninen oskillaattori

Tässä diplomityössä tutustuttiin kapasitiivisesti kytketyllä mikromekaanisella resonaattorilla stabiloidun sähkömekaanisen oskillaattorin teoriaan: resonaattorin mekaniikkaan ja vahvistimen elektroniikkaan. Esitetyn teorian pohjalta suunniteltiin ja rakennettiin sähkömekaaninen 500 kHz:n Pierce-oskillaattori. Prototyypin toiminta demonstroitiin mittauksin. Prototyypin mittauksissa todennettiin mikromekaanisen oskillaattorin värähtelytaajuuden ja -amplitudin riippuvuus resonaattorin biasjännitteestä; mittaustulokset olivat ennusteiden mukaiset. Oskillaattorin värähtelytarkkuutta kuvaava vaihekohina mitattiin tarkoitukseen suunnitellulla laitteistolla. Mitattu vaihekohina oli -123dBc@SkHz. Prototyypissä käytettiin palkkiresonaattoria, jonka epälineaarisuuden seurauksena oskillaattorin ulostulo oli säröytynyt. Työssä pohdittiin myös fysikaalisia rajoja palkkiresonaattoriin perustuvan mikromekaanisen oskillaattorin suorituskyvylle