Theodore C. Loder

Dissolved protein fluorescence in two Maine estuaries

Abstract Fluorescence of dissolved proteinaceous materials was examined in two estuaries differing primarily in river input. Low-wavelength excitation (220–230 nm) was found to be more useful than the high-wavelength excitation (280 nm) usually reported in the literature. Levels of fluorescence in estuarine samples were of the order to be expected from the probable levels of dissolved amino acids. However, quantitation of protein levels by fluorescence, even in relative terms, is virtually impossible, due to positive interferences among the two amino acid peaks and humic material and negative interference by various types of quenching. Salinity has little or no effect on quantum yield. Proteinaceous fluorescence along estuarine transects was noisy, with some positive correlations with chlorophyll levels. Noisy data are consistent with the short lifetimes of proteins in seawater. Sediments appeared to provide a source of proteinaceous fluorescence. Seaward samples tended to show higher tyrosine peaks while upstream samples were richer in tryptophan emission.

The dynamics of conservative mixing in estuaries

Mixing plots, in which a dissolved constituent is plotted against salinity or chlorinity, are commonly used to interpret conservative and non-conservative processes in estuarine systems. A bend in the resulting curve is generally interpreted as indicative of the reactive or non-conservative nature of the constituent or the presence of multiple sources or sinks within the estuary. This paper demonstrates analytically that bends in mixing curves may also result from temporal variations in end-member (river or ocean) constituent concentrations even for conservative constituents. A one-dimensional dispersion equation is used to calculate the distribution of salinity and a conservative constituent in a model estuary. Both straight and bent mixing curves are shown resulting simply from changing the variability of the river constituent concentration. For no variability the curve is straight. For variability with a period much less than the flushing time, the average curve for a general data set straight, whereas the curve for a synoptic data set is bent. For variability with a period greater than the flushing time a bent curve results. Since bent mixing curves can occur for conservative properties, the use of these curves for interpretation of estuarine processes must be undertaken with an understanding of the temporal variability of the river and ocean constituents and their relationship to the estuary mixing properties and flushing time.

Spring-neap tidal contrasts and nutrient dynamics in a marsh-dominated estuary

This contribution presents a new perspective on water chemistry and its relation to tidal hydrology in marsh-dominated estuaries. Results are derived from both field and modeling experiments. A heuristic model based on a tidally-averaged advection-dispersion equation is used in conjunction with source-sink terms (for benthic, marsh surface, and open-water exchanges) to make predictions of nutrient concentrations in the water column. Spring-neap tidal contrasts are associated with significant changes in water-column chemistry for a variety of nutrients sampled during the growing season in the Parker River estuary (Massachusetts). For ammonium, phosphate, nitrate plus nitrite, total dissolved N, and total dissolved P, concentrations are significantly lower during spring tides (marshes flooded) than during neap tides (marshes unflooded). Model results indicate that physical changes and open-water processing are insufficient to produce the observed effect, and that explicit biogeochemical processing on marsh surfaces is required. Field observations of changes in nutrient to nutrient ratios with the onset of marsh inundation also support this conclusion. As tides progress from the neap to spring condition, a “spectrum” of trajectories emerges in salinity-nutrient plots developed from both observational datasets and model output. Care must therefore be exercised in designing sampling programs for water chemistry in marsh-dominated ecosystems and in interpreting the resulting mixing diagrams.

Nutrient pore water chemistry, Great Bay, New Hampshire: Benthic fluxes

Benthic fluxes of C, N, P and Si have been measured at two sites in Great Bay Estuary, New Hampshire. Higher fluxes of reactive phosphate, nitrate and reactive silicate were observed at the site where bioturbation is known to occur and the fluxes of NH4+, PO4−3 and reactive silicate at this location were from 3 to 6 times higher than that calculated by simple pore water diffusion models. *** DIRECT SUPPORT *** A01BY019 00010

NUTRIENT VARIABILITY AND FLUXES IN AN ESTUARINE SYSTEM

Abstract Nutrient data from Great Bay Estuary, New Hampshire, were analyzed using a conservative mixing model to assess nutrient distribution and variability with time, and to determine a nutrient budget. Analytical precision was estimated as was the magnitude of short term (5 min intervals) environmental variability. Finally, monthly data were analyzed using this mixing model and a phosphate budget was calculated for a one year period. In well mixed waters, the short-term sampling showed that short-term mixing processes can mix estuarine waters so well that variability due to small-scale turbulence or imperfect mixing is less than the analytical and sampling variability. However, when the system is not well mixed then environmental variability can be distinct from analytical variability and may be attributed to some other process or processes. The conservative mixing model was then used to predict apparent average river concentration of phosphate based on the zero salinity intercept calculated with salinity and phosphate data from near the mouth of the estuary. Predicted average river concentrations agreed well with measured concentrations during winter and early spring, but were much higher during summer and fall. Total flux of dissolved phosphate into this estuary was calculated to be 70.7 × 105 moles/yr during 1976 with 78% of the input from municipal sewage and the rest from rivers (13%), sediment flux (7%) and rainfall (2%). Only about 12% of this dissolved phosphate was exported to coastal waters, while the rest of the phosphate apparently remained trapped in estuarine sediments.

Hydrographic and Nutrient Data from R/V KNORR Cruise 73, Leg 2 - February to March, 1978 - Off the Coast of Peru.

Prepared for the National Science Foundation under Grant OCE 77-26084, for the Office of Naval Research under Contract N00014-74-C-0262 ER 083-004 and for the NOAA Office of Sea Grant under Grants 04-7-158-44034 and 04-8-MO1-79 to the University of New Hampshire/University of Maine Cooperative Institutional Sea Grant Proqram.

OUTSIDE THE BOX SPACE AND TERRESTRIAL TRANSPORTATION AND ENERGY TECHNOLOGIES FOR THE 21 ST CENTURY

This paper reviews the development of antigravity research in the US and notes how research activity seemed to disappear by the mid 1950s. It then addresses recently reported scientific findings and witness testimonies - that show us that this research and technology is alive and well and very advanced. The revelations of findings in this area will alter dramatically our 20 th century view of physics and technology and must be considered in planning for both energy and transportation needs in the 21 st century.

Hydrographic and nutrient data from R/V Atlantis II cruise 108, leg 3 : March to April 1981 : off the coast of Peru

Prepared for the National Science Foundation under Grants OCE 77-12914, OCE 80-17877 and OCE 81-11947.

The chemical, physical and structural properties of estuarine ice in Great Bay, New Hampshire

Abstract The purpose of this study was to provide general information on the chemical, physical and structural properties of estuarine ice and show how it compares with sea ice found at higher latitudes in order to determine whether the ice in Great Bay can be used as an analog in the study of arctic sea ice. Ice cores and water samples were collected during the 1983–1984 winter season at Adams Point in Great Bay, New Hampshire. Concentrations of chloride, nitrogen (as nitrate and nitrite), bromide, phosphate, sulfate and silicate were determined for samples chosen on the basis of identifiable stratigraphic layers (i.e. bubble size and shape, sediment layers, etc.). Similarities between ice formation in Great Bay and those in the arctic regions include the nature of the freezing process and the ice types produced. In addition, the distribution and concentration of chemical constituents were found to be similar to those observed in arctic sea ice. Factors affecting the chemistry of the ice in Great Bay include rainfall during the freezing season, the presence of sediment layers in the ice cores, the nature of incorporation of brine into the crystal structure of the ice and the drainage of brine.