Environ. Sci. Technol. 1903, 17, 244-245
Impact of Fossil Fuel Combustion on Sediments of Lake Michlgan: A Reprise John J. Grlffln and Edward D. Goldberg" Scripps Institution of Oceanography, La Jolla, California 92093
The size distribution of charcoals in sediments of Lake Michigan reflects the onset of the industrial revolution and the increased intensities of fossil fuel combustion during the twentieth century. Prior to 1900 the less than 1-pm fraction was dominant, and its source was primarily biomass burning. In the subsequent years coal and oil burning became evident with larger particles, especially greater'than 32 pm, making larger contributions to the total charcoal concentrations. The input of the larger particles is a consequence of near fallout of particles from energy-producing plants near the lake. Previously, we have proposed that the amounts of charcoal found in the sedimentary record reflect the intensity of combustion processes at the earth's surface, both natural and anthropogenic ( I ) . For the case of Lake Michigan, the fluxes of charcoal from wood, coal, and oil burning changed over the past century and reflected the onset of industrial activity (Table I). The first strong evidence of coal utilization appeared about 1900. In addition, our results indicated that there was a decrease in charcoal concentrations in the deposits from about 1960 to the present, which we attributed to improved controls of emissions from the stacks of power plants and industrial facilities. We had analyzed the greater than 38-pm size class of the charcoals inasmuch as these particles possessed in their morphologies characteristics of the source material-oil, coal, or wood (2). Further, the twentieth-century urbanization of the lower Lake Michigan region, with its increasing production of energy needed for the production of goods and services to support an ever increasing population, impinged upon the lake environment. The places of commerce were sited along or near the lake, so as to take advantage of its natural resources, i.e., water and transportation. One manifestation of this impingement is the associated increase in the concentration of anthropogenic carbon in the lake sediments. Prior to 1900 the primary source of charcoal in the sediments was from burning of biomass. Two size classes of carbon particles are generated in burning coal, oil, and wood. The coarse fraction, generally greater than a few microns in diameter, is produced from incomplete combustion or pyrolysis of fuel particles. This carbon has been called charcoal, char, and coke. The second type includes the submicron particles produced from the vapor-phase condensation of carbon. This has been called soot and is composed of submicron spheres agglomerated into random chain-like structures (Figure 1). In this presentation we use the term charcoal to include both types of carbon. If we assume the fallout ratio of the two types is a function of particle size for a particular site, then a particle size gradient with the larger size particles near the source should be observed (3). Thus, we have determined the size distribution of charcoals in Lake Michigan Box Core LM780914, collected from a water depth of 64 m at 43'00' N and 86O22' W. This is the same sediment utilized in our previous studies in which the chronology of the strata, metal and charcoal concentrations, and mineral levels were determined (I). We recognize that a single core cannot be used to study 244
Environ. Sci. Technol., Vol. 17,
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Table I. Total Charcoal Concentrations in the Lake Michigan Deposit charcoal charcoal period of (dry weight), period of (dry weight), deposit ion % deposition % 1976-1978 197 3-1976 1970-197 3 1968-1970 1968-1970 1963-1968 1960-1963 1958-1960 1956-1958 1953-1956 1948-195 3 1943-1948 1938-1943 1933-1938 1928-1933 1923-1928
0.60 0.62 0.59 0.57 0.57 0.64 0.61 0.63 0.74 0.7 1 0.66 0.73 0.51 0.58 0.40 0.32
1920-1923 1918-1920 1916-1 918 1913-1916 1910-191 3 1908-1910 1906-1908 1898-1903 1893-1898 1883-1893 187 3-1 883 1863-1 87 3 1853-1863 1843-1857 18 37 -184 3 1827-1837
0.29 0.25 0.21 0.13 0.12 0.13 0.15 0.11 0.11 0.10 0.12 0.11 0.07 0.17 0.10 0.1 1
the integrated fluxes and the mass balances for sedimentary components in a water body the size of Lake Michigan. Still, a single core can reveal relative changes in fluxes, where the sedimentary strata can be dated, as was demonstrated in our previous work ( I ) . Our aim is to ascertain if there has been a change in size distribution over the past century and a half, during which period there was a change in fluxes of charcoal from a variety of sources as a consequence of the industrial revolution. The charcoal is isolated from the sediment in the following way. Oven-dried (110 "C) sediment samples were leached in hot 6 N HC1 from 2 to 4 h and subsequently carefully washed with H20. The residue was digested for about 2 weeks in a mixture of 300 mL of 10 N HF and 50 mL of concentrated HC1 at room temperature. The supernate is removed by careful centrifugation, and the residue is leached with hot 6 N HCl. The residue is then washed with H 2 0 in preparation for oxidation, which is accomplished by dispersing the residue in 100 mL of 6 N KOH and by the careful addition in small increments of 800 mL of 30% H202. After oxidation the residue is leached with hot 6 N HC1 and washed with H 2 0 in preparation for particle size analysis. Stokes settling techniques were used to separate the particles into the different size classes. The carbon particles were assumed to have a density of 2 g/cm3 and the settling medium was H20. Each size fraction was collected, oven-dried, and weighed and the charcoal concentration determined by infrared assay ( 4 ) . Samples that were too small for infrared assay had their charcoal contents determined by loss on ignition at 600 OC. Duplicate runs on the same sample showed both techniques give results within f10% of each other. Particle size distributions as a function of age of the strata are shown in Figure 2. The greater than 38-wm and the less than 1-pm fractions show trends over a time interval that was dated by the 210Pbgeochronology (I). As previously noted (2), the greater than 38-pm particle concentration showed an increase beginning about 1900. Furthermore, these charcoals had morphologies indicative of coal sources and to a lesser extent those of oil, whereas the contribution from wood charcoal decreased from 1900
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@ 1983 American Chemical Society
Environ. Sci. Techno/, 1983. 17, 245-248
npue 1. hkqhkgy of Um very firegrained hrcoal. have aggregated into irregular chains.
Small spheres
sources of this fallout would be the energy-producing plants sited along the shore of the lower Lake Michigan basin. As the region's economic activities and population matured and stabilized over the past decades, these stationary energy-producing sources proved to be a stable source of particles whose variations are affected by the economy and/or improvements in combustion and pollution-control technology. The fine fraction (less than 1 rm) has a rather constant concentration (2&30%) during the past 40 years, whereas the older strata show a concentration increase that is variable with no distinct trends. The low values during the past 40 years are the result of dilution by the large particles with a fossil fuel origin. The increase in the fine fraction in older sediment is correlated with the very low concentration of large particles. These large particles have morphologies indicating a wood origin and probably have their origins in burning of biomass by man and through natural phenomena. This biomass burning would not he limited to a few fixed geographic areas but would range over the entire lower Lake Michigan basin. The same volume of biomass would not be regularly combusted hut would vary depending upon available fuel and upon favorable conditions for burning. The fine-grained nature indicates a more distant source and represents long-distance transport and fallout. This would be in keeping with the early development of the region as it transformed from a prairie to an agricultural area and then to its present industrial economy. Thus we have identified a number of parameters associated with charcoals that may be useful in reconstructing burning histories from the sedimentary record charcoal concentrations, morphologies, and size distributions.
Literature Cited (1) Goldberg, E. D.; Hcdge, V. F.; Griffin, J. J.; Koide, M. 2. Percent of total carbon in size lractbns as a function 01 depth and age of strata. The geachronology was obtained by "'Pb dating ( 1 ) .
Enuiron. Sci. Technol. 1981.15.466-471. (2) Griffin, J. J.; Goldberg, E. D.'Science (Washington, D.C.) 1979,206, 563-565. (3) Windom, H. L. Bull. Geol. SOC.Am. 1969,80, 761-782. (4) Smith. D. M.: Griffin. J. J.: Goldbere. E. D. Anal. Chem.. 1975, 47, 233-238.
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to the present. The use of morphologies to identify the origin of charcoal particles previously has been described by us (2). This increase in large particles over the past EO years indicates a short-range transport from the source areas and therefore nearby sources of fallout. The most probable
Receiued for reuiew June 11,1982. Accepted December 27,1982. Research funded by the National Science Foundation, Geochemistry Program (EAR80-17491).
Electrolytic Preparation of [38CI]Chlorine Dioxide from H3*CI Hosseln A. Ghanbarl,' Wlllls B. Wheeler, and James R. Kirk
Department of Food Science and Human Nutrition, Instlute of Food and Agricunurai Sciences. University of Florida. GainesvUle. FIor!da 32611 Electrolysis of KOH-neutralized H"CI resulted in greater than 90% conversion of K"C1 to K W 0 3 . Reduction of KW103 with oxalic acid in a closed gas-generation system yielded W102gas. The generated gas was passed through a Na2C03column, which effectively absorbed the contaminants C1, and COP, and the purified W10, was then dissolved in water. This nrocedure is an _..~~~. effective laboratory preparation of"C10, and is characterized by high yield, purity, and specific activity. ~~~
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Wide use of C102 as a disinfectant has led to studies involving the metabolism of C102 (I, Z), the mode of 0013-936X/83/0917-0245$01.50/0
bacterial or viral inactivation (2-9),and the fate of chlorine (IO). These studies and others such as C102toxicity and the mechanism of bactericidal action would be greatly facilitated if "C102 were either commercially available or could be synthesized easily in the laboratory. In order to study the reactivity of '210, with biological molecules, radioactive chlorine dioxide was used. Radioactive chlorine dioxide is not commercially available as a stock item, and chlorine-36 is marketed primarily as HWI. This paper describes an electrolytic method for the preparation of high-purity, high specific activity W O , in good yield from commercially available HWI.
0 1983 American Chemical Society
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