The elemental analysis of humic substances isolated from the Suwannee River in southern Georgia, from the Biscayne groundwater near Miami, FL, and the Laramie-Fox Hills groundwater, Superior, CO, are shown in Table V. Typically, ash contents are less than 1%by this method (only exception is the humic acid from Laramie-Fox Hills groundwater). Therefore, it is possible to concentrate humic substances and purify them from the bulk of inorganic constituents in water, even when the DOC of the water is 0.7 mg C/L, and the humic concentration is 50 pg/L DOC.
Literature Cited (I) Schnitzer, M.; Kahn, S. U. “Humic Substances in the Environment”; Marcel Dekker: New York, 1972. (2) Rook, J. J. Enuiron. Sci. Technol. 1977,11,478. (3) Van Vleet, E. S.; Quinn, J. G. Enuiron. Sci. Technol. 1977, 11, 1086. (4) Jeffrey, L. M.; Hood, D. W. J . Mar. Res. 1958,17, 247. (5) Martin, F. D.; Pierce, R. H., Jr. Enuiron. Lett. 1971,1,49. (6) Gjessing, E. T. Enuiron. Sci. Technol. 1970,4,437. (7) Eberle, S. H.; Schweer, K. H. Vom Wasser 1974,41, 27. ( 8 ) Malcolm, R. L. Geol. Suru. Prof. Pap. ( U S . )1968,600-C, 211. (9) Riley, J. P.; Taylor, D. Anal. Chim. Acta 1969,46, 307. (10) Mantoura, R. F. C.; Riley, J. P. Anal. Chim. Acta 1975, 76, 97. (11) Weber, J. H.; Wilson, S. A. Water Res. 1975,9, 1079. (12) Leenheer. J. A,: Huffman. E. W. D.. J r . J . Res. U.S. Geol. Suru 1976,4,737. (13) Malcolm, R. L.; Thurman, E. M.; Aiken, G. R. Trace Subst. Enuiron. Health 1977,11,307. (14) Gustafson, R. L.; Albright, R. L.; Heisler, J.; Lirio, J. A,; Reid, 0. T. Ind. Eng. Chem. Prod. Res. Deu. 1968, 7,107.
(15) Simpson, R. “The Separation of Organic Chemicals from Water”; Rohm and Haas: Philadelphia, PA, 1972. (16) Burnham. A. K.: Calder. G. V.: Fritz. J. S.: Junk. G. A,: Svec. H. J.; Willis, R. Anal. Chem. 1972,44, 139. (17) Grieser, M. D.: Pietrzvk. D. J. Anal. Chem. 1973.45,1348. (18) Junk, G. A,; Richard,’J.’J.; Grieser, M. D.; Witiak, D,; Witiak, J. L.; Arguello, M. D.; Vick, R.; Svec, H. J.; Fritz, J. S.; Calder, G. V. J . Chromatogr. 1974,99,745. (19) Chu, C.; Pietrzyk, D. J. Anal. Chem. 1974,46,330. (20) Pietrzyk, D. J.; Chu, C. Anal. Chem. 1977,49,757. (21) Pietrzyk, D. J.; Chu, C. Anal. Chem. 1977,49, 860. (22) Pietrzyk, D. J.; Kroeff, E. P.; Rotsch, T. D. Anal. Chern. 1978, 50, 497. (23) Thurman, E. M.; Aiken, G. R.; Malcolm, R. L. “Proceedings of the 4th Joint Conference on Sensing of Environmental Pollutants”, 1977. (24) Thurman, E. M.; Malcolm, R. L.; Aiken, G. R. Anal. Chem. 1978,’ 50, 775. (25) Aiken, G. R.; Thurman, E. M.; Malcolm, R. L. Anal. Chem. 1979, 51,1799. (26) Malcolm, R. L.; McKinley, P. W. “Methods for Analysis of Organic Substances in Water”; Goerlitz, D. F.; Brown, E., Eds.; U.S. Geological Suruey Techniques of Water Resources Inuestigations Supplement I , 1972. (27) Thurman, E. M.; Malcolm, R. L. Geol. Suru. Water-Supply Pap. ( U . S . )1979,No. 1817-G. (28) Malcolm, R. L. J . Res. U.S. Geo2. Suru. 1976,4,37. (29) Gustafson, R. L.; Paleos, J. “Interactions Responsible for the Selective Adsorption of Organics on Organic Surfaces”. In “Organic Compounds in Aquatic Environments”; Faust, S. J., Ed.; Marcel Dekker: New York, 1971. Receiued for review July 2,1980. Accepted December 12,1980. The use of brand names in this report is for identification purposes only and does not imply endorsement by the U.S. Geological Survey.
Impact of Fossil Fuel Combustion on the Sediments of Lake Michigan Edward D. Goldberg,” Vernon F. Hodge, John J. Griffin, and Minoru Koide Scripps Institution of Oceanography, La Jolla, California 92093
David N. Edgington Center for Great Lakes Studies, University of Wisconsin, Milwaukee, Wisconsin 53021
The inputs of metals to a southern Lake Michigan sediment covary with the fluxes of charcoals whose morphologies and surface characteristics are indicative of different combustion processes-oil, coal, and wood burning. Sn, Cr, Ni, Pb, Cu, Co, Cd, Zn, and Fe showed increasing concentrations in sediments deposited between ca. 1930 and 1968, after which time they showed slight decreases in concentration. A similar profile was found for the total charcoal concentration. The maximum appears to be a consequence of the installation of improved control devices to remove fly-ash from the stack gases. During the time period following the maximum, there are reported lower levels of total suspended particulates in the terrestrial atmosphere adjacent to Lake Michigan. The increased metal and charcoal concentrations in recent sediments were accompanied by increased numbers of magnetic spherules of fly-ash.
Introduction Natural and anthropogenic combustion processes mobilize a large variety of materials about the environment. Some of these materials may be toxic to living organisms or may degrade the environment; others may be innocuous. Since the nature of the combustion process often determines the types of materials released and since there is a very large number 466
Environmental Science & Technology
of such processes, the fluxes of the combustion products to the environment can best be ascertained through field, as opposed to laboratory, studies. I t was with this view in mind that we initiated an investigation of the combustion products in the sediments of Lake Michigan ( I ) . The deposits of Lake Michigan have received solid phases from a variety of combustion processes over the past century or two. Natural wood and brush burning were dominant before the 19th century. Forest clearance appears to have begun in the early 1800s on the basis of pollen studies and geochronological investigations ( 2 , 3 ) .Coal combustion becomes evident in the sedimentary record a t the beginning of the 20th century through the characteristic morphologies and dimensions of the associated charcoal (1). Oil combustion charcoals were identified in strata deposited after 1928. In 1971, coal and oil burning contributed 6.4 and 1.4%,respectively, to the atmospheric particulates ( 4 ) . In our previous report, the morphologies and dimensions of the carbon particles indicated that in the period 1953-1978 -76% had an origin in coal burning, 14% in oil burning, and 10%in wood burning. Before this work, several investigations emphasized the importance of coal burning ( 5 , 6 ) The . latter workers argued that 95% of the lead in the sediments of Lake Michigan could be accounted for by coal and gasoline combustion; over 95% of the lead dispersed was transported to the deposition site from land through the atmosphere. 0013-936X/81/0915-0466$01.25/0
@ 1981 American Chemical Society
It appeared to us that the characteristic charcoals produced by wood, coal, and oil burnings can act as tracers or sentinels for associated substances disseminated about the environment. We are aware of some inadequacies in this approach. First of all, some of the dispersed materials may only indirectly be associated with energy-producing processes and yet still covary in environmental sinks with the charcoals, Le., the fly-ashes produced in extractive metallurgical activities. Further, improved control devices to capture the fly-ashes in recent years would alter any direct relationships between the amounts of burned fuels and the released materials. This appears to be the case in the Lake Michigan area, when the particulate levels in the atmosphere decreased substantially in the late 1960s. Lake Michigan deposits seemed especially attractive to us. First of all, the surrounding land areas have played host to intensive agricultural and industrial activities, which can mobilize materials about the surroundings. Secondly, their strata can be dated by Pb-210, artificial radioactivity, and pollen techniques (3, 7). Also, there have been extensive geological and limnological investigations upon Lake Michigan which provide an information base upon which to assess the results of our investigations. For example, atmospheric fallout was first indicated as an important source of metal to Lake Michigan (6). These investigators compared the fluxes of stream-borne materials with those calculated for atmospheric fallout and concluded that the atmosphere may be a major pathway for zinc, as well as for copper and nickel. They indicate that for other elements the atmosphere may contribute substantially to the annual inputs to Lake Michigan. The sources for the atmospheric particulates include (1)coal burned for energy and heating, (2) emissions from coke ovens, (3) petroleum burned for energy and heating, (4) automotive fuels, ( 5 ) emissions from iron and steel plants, and (6) emissions from cement production. The compositions of the emissions from these sources were obtained from the published literature. Coupling this data with the intensity of these activities in the Lake Michigan area, the investigators concluded that Fe, Mn, Cu, and Zn come primarily from the iron and steel industry. Cr, As, Sn, Ni, V, and perhaps Ti have sources in coal, coke, and fuel oil, while P b has an origin in the combustion of the antiknock agents, lead alkyls, in automotive engines. The investigators recognize the fragmentary nature of their data and emphasize the need for additional information to assess these findings. A detailed study of the lead inputs to Lake Michigan was carried out by Edgington and Robbins ( 5 ) .The lead concentrations in Pb-210-dated cores reflected inputs from the burning of coal and of leaded gasolines. These anthropogenic fluxes 1.3 pg/(cm2 yr) mask the natural fluxes (-0.16 pg/(cm2 yr) for 1972.The total anthropogenic lead in 1972 fallout over the southern basin of the lake was estimated to be 230 metric tons; the sediment deposition of lead was found to be -240 metric tons. This is a most satisfying agreement. There are several important concepts from this latter work which are relevant to this investigation. First of all, the total suspended particulates in Chicago air are reported therein to have decreased by a factor of 2 over the 10-yr period prior to the publication of these results (1966-1976). This is in agreement with the U.S. reduction in emissions from conventional sources (8).The value of 22.2 megatons per year in 1970 fell to 12.4 megatons per year in 1977. Secondly, the results are in accord with the argument of Winchester and Nifong (6) that most of the anthropogenic lead is brought to the lake via the atmosphere. Finally, they recognize a redistribution of lead in the upper few centimeters of the deposits, a situation they attribute to bioturbation and microturbulence. These phenomena have the effect of moving lead to
deeper levels of the deposit. The goal of this investigation is to seek relationships between metal and mineral contents of the Lake Michigan sediments and their charcoal contents, the latter presumably a sentinel for combustion processes. Sample Description and Methodology The Box Core LM-780914 was recovered on September 14, 1978,from the southern part of Lake Michigan at 43'00" and 86'22'W. The water depth was 64 m. Core dimensions were 30 X 30 X 60 cm. The charcoal particles were isolated by techniques previously described (9). Briefly, the acid-soluble and silicate minerals were destroyed by an HF-HCl dissolution, and the organic phases were removed by dissolution and oxidation with a KOH/H202 mixture. The remaining residues were fractionated on the basis of their sizes and densities to yield a >38-ym fraction with a charcoal purity of -90%. This fraction was weighed and studied by microscopy. The magnetic fraction was separated by using a Frantz isodynamic separator modified to accept an aqueous slurry of the micrometer-sized separated sediment. We expected to recover both the naturally occurring magnetic minerals such as hematite and magnetite and the strongly magnetic components of fly-ash. The quartz and mullite particles, often found in fly-ash, escape this separation. Quartz was assayed by X-ray diffraction techniques using CaF2 as an internal standard. The heavy metals were analyzed by standard atomic absorption methodologies. Time frames were introduced by using Pb-210 and plutonium geochronologies (Table I and Figure 1).A sedimentation rate of 0.4 cm/yr is derived from the Pb-210 profile. There appears to be some bioturbation or physical mixing to a depth of -3 cm on the basis of the scatter of the Pb-210 concentrations over this interval. Such a mixing depth is in accord with the plutonium data. There is a maximum in the Pu-239+240 activity at a depth of -7-8 cm. We suspect this corresponds to a mixing of the plutonium isotopes from the U.S.S.R. weapons tests (1963) and those of the U S . (1959) which would produce a peak a t ca. 1961. On the basis of the Pb-210 chroTable 1. Radionuclides in Lake Michigan Core 780914 Pb-210, dPm/Q
depth,
cm
0.5-0.5 0.5-1.0
1.1-1.4 1-2 2-3 2.4-2.7 3-4 4-5 5-6 6-7 7-8 8-9 9-10 10-10.3 10-14 14-15 15-18 18-19 20-20.3 29-30 54-55
Pu-2394-240, dpm/kg
PU-238/Pu-239+240 acilvliy ratio
16.9f 0.9 14.1 f 0.4 15.4f 0.7 66.5f 2 72.0f 4
0.047f 0.01 0.043f 0.01
17.2 f 0.7 75.0f 4 10.9f 0.8 101 f 3 113f3 136 f 4
0.047f 0.006 0.05f 0.005 0.029 f 0.003
1 1 .O f 0.4 46.5f 1.6
0.040 f 0.007
11.6 f 0.7
-
5.0 f 0.3
6.5f 0.4 1.8f 0.06 6.3 f 0.2 4.16 f 0.25 2.13f 0.05 1.16f 0.08
Volume 15,Number 4,April 1981
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0
10 9 8 7
SEDIMENTATION RATE: 4 MM. / Y R .
6
I
I
I 1970
- I
5 41
31
21 W 1
L a D
z
I(
0 N n
'10 CARBON by WEIGHT
>38p
Figure 2. Charcoal (elemental carbon)concentration as a function of depth in the Lake Michigan core.
SEDIMENT DEPTH IN CM
Figure 1. Pb-210
activity as a function of depth in the Lake Michigan
core. nology, the 1961 strata would have deposited a t a depth of -7 cm, in accord with the Pu-239+240 chronology. Similarly, the first measurable plutonium usually occurs in strata deposited around 1954 or, in this core, on the basis of the Pb-210 data, at 10 cm. The measurement a t 10-14 cm appears to be the first unequivocal occurrence of plutonium isotopes, which is in accord with the Pb-210 results.
Results Charcoal. The amount of charcoal in the >38-pm fraction as a function of age (depth) in the deposit is essentially constant in the oldest samples up to ca. 1900 (Figure 2). (The
