J. Gordon Ogden

The chemistry of streams in southwestern and central Nova Scotia, with particular reference to catchment vegetation and the influence of dissolved organic carbon primarily from wetlands

The percentage of wetlands in a catchment accounted for about half of the variance in transformed data for concentrations of dissolved organic carbon (DOC) in 42 Nova Scotian streams draining catchments with 11 different kinds of vegetation. Color increased with DOC, as did total dissolved nitrogen (TDN). Thecolor/DOC andDOC/TDN quotients also rose with increasing DOC, indicating a change in the quality of dissolved organic matter with increasing wetland influence. Dissolved Fe, and to a much lesser extent dissolved Al, showed a strong positive correlation with DOC. Stream pH showed a strong negative correlation with DOC, largely from wetlands, and a strong positive correlation with non- marine Ca2+ weathered from mineral soils. Non-marine SO42− from acid deposition had no apparent influence on stream pH and decreased with increasing streamwater DOC in summer, presumably owing to reduction processes in wetlands that mitigated the effects of acid deposition. Apparently, these reduction processes also produced small amounts of dissolved, non-ionic organic sulfur. Non-marine Ca2+ was related strongly to the percentage of upland hardwood forests in the catchments. Wetlands exert a profound influence on the chemistry of streams, principally through their export of DOC but also because of reduction reactions in their anerobic peats.

Intestinal Contents of a Late Pleistocene Mastodont from Midcontinental North America

Abstract Salvage excavations of a nearly complete and remarkably well-preserved skeleton of an American mastodont ( Mammut americanum ) in Licking County, Ohio, yielded a discrete, cylindrical mass of plant material found in association with articulated vertebrae and associated ribs. This material is interpreted as intestinal contents of the mastodont and paleobotanical analyses indicate that the mastodont diet included significant amounts of low, herbaceous vegetation. Enteric bacteria ( Enterobacter cloacae ), isolated from a sample of this material, are believed to represent survivors or descendants of the intestinal microflora of the mastodont. This is the first report of the isolation of bacteria associated with late Pleistocene megafauna.

THE LATE QUATERNARY PALEOENVIRONMENTAL RECORD OF NORTHEASTERN NORTH AMERICA

Since 1930, the pollen stratigraphy of more than 300 sediment cores has been reported from northeastern North America. More than half of these studies were based on arboreal or tree pollen counts only. The advent of radiocarbon dating in the 1950’s made possible the calibration of pollen-stratigraphic sequences, utilizing an hdependent geochemical technology. Despite the availability of radiocarbon dating, fewer than one-third of the sequences have any radiocarbon determinations, and only about 20 have multiple determinations which permit careful calibration of sedimentation rates. Increasing sophistication of sample preparation and counting techniques, spearheaded by M. B. Davis and her co-workers,l-10 has produced pollen diagrams based on absolute pollen influx rates, e.g., as pollen grains cm-’ yrl . A principal advantage of these techniques is the removal of the statistical restrictions of “closed universe” populations based on ratios. The explosive development of larger and more powerful computers and computer language since the mid-1 960’s has provided the pollen analyst with tools of spectacular power. The ability to manipulate massive data sets with mind-boggling ease places an increasing responsibility upon the investigator t o be sensitive to distributional problems associated with data sets of uneven quality, e.g., with or without nonarboreal pollen, moss polsters vs. lake sediments or bogs, absolute or relative pollen counts, and counting to fixed or variable pollen sums. Preliminary efforts to reconcile pollen and vegetational records by Ogden’ are being refined by Davis and Webb * and are the subject of active consideration by numerous investigators (Andersen,l Janssen,14LichtiFederovich and Ritchie18). Some of the more intractable problems under study include pollen production (Wrightz1 1, pollen dispersion, filtration and deposition (Tauber,’ 9*20 E. C. Ogden,22 and R a y n ~ r , ~ ~ Jamsenl4), resuspension and redistribution of pollen grains in lakes (Davis6), and statistical treatment of pollen data ( M o ~ i m a n n , ~ ~ ~ ~ Yarranton and R i t ~ h i e ~ ~ ) . Increasing attention to paleoclimatology (Lamb,27*28 Bryson et al.29930) and the use of powerful multivariate statistical techniques have enabled the generation of transfer functions to contrast pollen records and vegetation types with climatic shifts, such as weather-generating air-mass movements since deglaciation (Webb and Bryson3 ’ ). Exciting possibilities are inherent in these approaches, such as recognition of changes in the length of growing seasons, of summer temperatures and moisture stress, as well as other important climatic variables of plant growth and distribution. That’s the good news. Somewhat earlier in the Pleistocene, Ogdenll ungraciously observed, “The use of statistical procedures can scarcely be justified unless it is possible to derive inferences and conclusions from their use that would not be possible otherwise. The further restriction that applicable

Shoreline changes along the southeastern coast of Martha's Vineyard, Massachusetts for the past 200 years

Shoreline changes since 1776, including two 30-yr periods separated by nearly 100 yr are documented from surveys, topographic maps, harbor charts, and aerial photographs for the southeastern corner of the island of Marthas Vineyard, Massachusetts (41°25′ N, 70°35′ W). From 1776 to 1969, a barrier beach has receded by more than 880 m, and average rate of 4.6 m/yr. A series of four detailed surveys from 1840 to 1886 document consistent shoreline retreat in this area of 3.1 m/yr. For the period 1938–1969, planimetry from aerial photographs and field observation indicate that more than 28 ha and nearly 3 × 106 m3 of foreland composed of till have washed away. A house, located 200 m from the cliff edge of the foreland in 1938 was only 56 m from the cliff edge in July 1972. Violent storms were associated with the opening of the bay behind the barrier beach in nearly the same location in 1856, 1886, 1938, and 1954. Easterly migration of the opening results in rapid erosion of the southeastern corner of the island (Wasque Point) and eventual closing of the opening. Field observation of the 1954 opening indicates that the mechanism of failure of the barrier beach is primarily by storm tide-induced subsidence. Subsequently, strong (up to 1.2 mps) easterly currents cause migration of the opening to the east and closure within 15 yr. A summary review of evidence for changes in sea level in the past is suggested in partial explanation for the consistent shoreline retreat described in this paper.

Seasonal mass balance of major ions in three small watersheds in a maritime environment

Three watersheds (16.4, 544, and 83 ha) at distances of 0.5, 20, and 40 km from the Atlantic coast have been monitored for major ion chemistry of precipitation input and streamflow from May 1977 to November 1978. More than 200 precipitation and stramflow samples were analyzed for Na, K, Ca, Mg, chloride and sulphate, as well as pH, conductivity, alkalinity, and compared to similar studies at Hubbard Brook, New Hampshire, U.S.A., and Kejimkujik National Park, Nova Scotia. Major ion chemistry reflects proximity to Atlantic and Bay of Fundy coastal sources of marine aerosols. Evidence is presented implying biological reduction ofH + and SO 4 to H2S during summer months for two consecutive growing seasons. Weighted mean annual pH values of precipitation for the three watersheds in Nova Scotia range from 4.11 to 4.63. More than 50% of the H + in precipitation is retained in the watersheds (with the exception of the ombrotrophic Fink Cove ecosystem), principally at the expense of basic cations being leached from the watersheds. Acidic deposition of Nova Scotian precipitation is predominantly as sulphuric acid, in contrast to ammonium sulphate, characteristic of continental precipitation.

THE USE AND ABUSE OF RADIOCARBON DATING

Although most of you know the general theory of radiocarbon dating and many may know more than I about the mechanics of the process, nevertheless, I think it might be interesting for some of you to hear the story of how radiocarbon dating got started. One of the very curious facts in the history of radiocarbon dating is that the radioactive isotope of carbon, 14C, was produced in a laboratory some time before its existence was known in nature. As a matter of fact, it was manufactured at the request of a plant physiologist by a physicist for the expressed purpose of providing a tracer for use in biochemical studies. Behind that story, however, lies the research that ultimately lead to the development of atomic weapons. Not long after Roentgen had discovered x-rays in 1896, the medical profession began to realize that high-energy radiation was a tool of considerable value in diagnosis and treatment of disease. In the early part of the twentieth century, much of high-energy physics research was sponsored by the medical profession. By the middle 1930’s, generation of radioactive substances by particle accelerators, such as the cyclotron, was receiving considerable support from the medical profession. About this time, Martin Kamen, a physicist at the University of California, was assigned to the production of large amounts of the thenknown radioactive isotope of carbon, C . This substance had a half-life of 21 minutes, in other words, 50% of its radioactivity was lost every 21 minutes. While Ruben attempted to complete biochemical experiments based on a detectable period of about 90 minutes, Kamen became involved in a search for a longer lived isotope of carbon. All of the known nuclear reactions that could be employed with the equipment then available were used in this study. It is a curious fact that the most successful reaction was the one considered to be least likely to succeed! Although the details of the research program need not concern us, the actual discovery of 14C is a matter of some interest. In general the two approaches involved the use of fast or high-energy neutrons, or the use of slow or thermal neutrons. Again, for our purposes we may simply view this as a kind of atomic shotgun with different powder charges behind the projectiles or neutrons. Although the fast neutron scheme seemed theoretically the most promising, the slow neutron system was included, largely for the sake of completeness. The set-up was not particularly elaborate, for all they used were two 5-gallon carboys of acidified ammonium nitrate placed near a source of thermal neutrons. (The reason for the use of ammonium nitrate is that the anticipated reaction involved the conversion of 14N to I4C, and ammonium nitrate is a good source of nitrogen). They carefully removed all COz from the carboys, sealed them, and went on about their business. About this time they got their first results with high-energy neutrons and succeeded in proving that they had found a radioactive isotope of carbon and

Acidification of Nova Scotia Lakes I: Response of Diatom Assemblages in the Halifax Area

A comparison is made of diatom remains in surficial lake sediments collected in 1971 and 1980. Changes of similar magnitude towards more acid tolerant assemblages are observed in four lakes studied in detail despite widely differing aquatic environments. No attempt is made to reconstruct past chemistry, the significant point being that at the most fundamental level, local lacustrine biological systems are being stressed to the point of alteration. The pattern of that alteration with emphasis on ‘simplification’ is discussed with the suggestion that rates of acidification may be as important as net changes.

Oxygen demand of effluent from a bleached kraft pulp mill

Total solids input to the treatment system (determined by evaporation at 105°C) amounts to 1.29 g l−1. Settling and oxidation in the basin accounts for approximately 0.29 g l−1. Based on plant flow rates of 95 x 106 1 per day, nearly 100 metric tons of solids are released to the marine environment daily.

Limiting Factors in Paleoenvironmental Reconstruction

It is a basic tenet of paleoecologists that the data set, consisting principally of pollen, spores, diatoms, or other microfossils and the enclosing sediment, is better than anything yet done with it. Distributional problems include differential pollen production, dispersal, sedimentation, and preservation. Changes in dominant air mass patterns, whether seasonal or in response to climatic trends, alter source pollen frequency independently of vegetational sources near depositional sites. Approximately 50% of the pollen at the center of a small (ca 1 km diam.) pond comes from within 7 km of the site, and from less than 300m of the source in a bog. With more than 300 published pollen sequences and nearly 500 contemporary pollen records available in North America since the 1230s, the sampling interval, even if uniformly spaced, is ca 10 km per sample site. At this spacing, approximately 11 stations at 110 km intervals would be available to describe the vegetational diversity of Ohio.