Flow and nutrient dynamics in a subterranean estuary (Waquoit Bay, MA, USA) : field data and reactive transport modeling

Author Posting. © Elsevier B.V., 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 72 (2008): 3398-3412, doi:10.1016/j.gca.2008.04.027.A two-dimensional (2D) reactive transport model is used to investigate the controls on nutrient (NO3-, NH4+, PO4) dynamics in a coastal aquifer. The model couples density dependent flow to a reaction network which includes oxic degradation of organic matter, denitrification, iron oxide reduction, nitrification, Fe2+ oxidation and sorption of PO4 onto iron oxides. Porewater measurements from a well transect at Waquoit Bay, MA, USA indicate the presence of a reducing plume with high Fe2+, NH4+, DOC (dissolved organic carbon) and PO4 concentrations overlying a more oxidizing NO3--rich plume. These two plumes travel nearly conservatively until they start to overlap in the intertidal coastal sediments prior to discharge into the bay. In this zone, the aeration of the surface beach sediments drives nitrification and allows the precipitation of iron oxide, which leads to the removal of PO4 through sorption. Model simulations suggest that removal of NO3- through denitrification is inhibited by the limited overlap between the two freshwater plumes, as well as by the refractory nature of terrestrial DOC. Submarine groundwater discharge is a significant source of NO3- to the bay.This research was funded by the Netherlands Organisation for Scientific Research (NWO) and WHOI Guest Student Program (C. Spiteri), the Royal Netherlands Academy of Arts and Sciences (KNAW) and the Netherlands Organization for Scientific Research (NWO VIDI-grant) (C.P. Slomp), the US National Science Foundation NSF-OCE0095384 and NSF-OCE0425061 (M.A. Charette) and the Georgia Sea Grant of the National Sea Grant College Program of the U.S. Department of Commerce’s National Oceanic and Atmospheric Administration under NOAA Grant #NA04OAR4170033 (C. Meile)

An index and summary of Oregon building information in the Portland Daily Abstract : 1906-1910

8 volumes represented in 29 separate pdf documents of about 100 pages each.Index 1-2A. Topics other than specific buildings ; Buildings sorted by city and building (Portland excluded) -- Index 2B. Portland buildings sorted by building names -- Index 3. Buildings sorted by names of architects/designers -- Index 4. Buildings sorted by names of contractors and other names -- Indexes 5-7. Buildings sorted by significant features ; Buildings sorted by use (houses excluded) ; Portland buildings sorted by section and primary street -- Indexes 8-10. Portland buildings sorted by section and second street ; Portland buildings sorted by section and third street ; Portland buildings sorted by district or addition (partial list) For an extensive guide to this resource see: https://libweb.uoregon.edu/aaa/shellenbarger.htmlIndex 1-2A. Topics other than specific buildings ; Buildings sorted by city and building (Portland excluded) -- Index 2B. Portland buildings sorted by building names -- Index 3. Buildings sorted by names of architects/designers -- Index 4. Buildings sorted by names of contractors and other names -- Indexes 5-7. Buildings sorted by significant features ; Buildings sorted by use (houses excluded) ; Portland buildings sorted by section and primary street -- Indexes 8-10. Portland buildings sorted by section and second street ; Portland buildings sorted by section and third street ; Portland buildings sorted by district or addition (partial list

Harmony in diversity : the architecture and teaching of Ellis F. Lawrence

88 page

Oregon inventory of historic places

7 v. : ill., maps, plans ; 28 cmA print copy of this title is available through the UO Libraries under the call number: AAA NA737.L38 E45 1989v. 1. [Introduction and index] -- v. 2. [Eugene] -- v. 3. [Portland, pt. 1] -- v. 4. [Portland, pt. 2] -- v. 5. [Portland, pt. 3] -- v. 6. [Cities A-PE] -- v. 7. [Cities PR-Z

New perspectives on radium behavior within a subterranean estuary

Over the past decade, radium isotopes have been frequently applied as tracers of submarine groundwater discharge (SGD). The unique radium signature of SGD is acquired within the subterranean estuary, a mixing zone between fresh groundwater and seawater in coastal aquifers, yet little is known about what controls Ra cycling in this system. The focus of this study was to examine controls on sediment and groundwater radium activities within permeable aquifer sands (Waquoit Bay, MA, USA) through a combination of field and laboratory studies. In the field, a series of sediment cores and corresponding groundwater profiles were collected for analysis of the four radium isotopes, as well as dissolved and sediment associated manganese, iron, and barium. We found that in addition to greater desorption at increasing salinity, radium was also closely tied to manganese and iron redox cycling within these sediments. A series of laboratory adsorption/desorption experiments helped elucidate the importance of 1) contact time between sediment and water, 2) salinity of water in contact with sediment, 3) redox conditions of water in contact with sediment, and 4) the chemical characteristics of sediment on radium adsorption/desorption. We found that these reactions are rapid (on the order of hours), desorption increases with increasing salinity and decreasing pH, and the presence of Fe and Mn (hydr)oxides on the sediment inhibit the release of radium. These sediments have a large capacity to sorb radium from fresh water. Combined with these experimental results, we present evidence from time series groundwater sampling that within this subterranean estuary there are cyclic periods of Ra accumulation and release controlled by changing salinity and redox conditions