Ocean sciences___________________________ Water-column ...
Ocean sciences___________________________ Water-column particulate flux and seafloor deposits in the Bransfield Strait and southern Ross Sea, Antarctica
R.B. DUNBAR Department of Geology Rice University Houston, Texas 77251
A.J. MACPHERSON Antarctic Research Centre Victoria University of Wellington Wellington, New Zealand
G. WEFER Geologisches Institut Universitdt Kid Kiel, Federal Republic of Germany
A recent proliferation of moored sediment-trap experiments and surface sediment collection has allowed us to begin to characterize the complex water column and seafloor processes which govern sedimentation on the antarctic continental shelf. Each summer, as the annual sea ice breaks up and melts, emerging areas of open water are sites of episodic algal blooms and the production of large amounts of particulate matter enriched in opal and organic carbon. Biogenic phases are also produced within the basal portion of the sea ice (Sullivan et al. 1982). Only a fraction of the particulate matter produced in the photic zone actually accumulates in shelf deposits, because these phases may be readily dissolved, degraded, or winnowed both in the water column and at the seafloor. Here we compare vertical fluxes and concentrations of biogenic components in the water column with the composition of sediments at the seafloor of the Antarctic Peninsula and the southern Ross Sea. These areas appear to represent two end-member environments in terms of particle transport, recycling, and deposition. Our ultimate goal is to construct a quantitative model for the production or input of both terrigenous and biogenic sedimentary components and their subsequent modification within the water column or at the seafloor. Such models are prerequisites for retrospective studies involving shelf sediments and also provide important insight into nutrient element recycling in this unique environment. 98
Surface sediment data is derived from samples collected by Rice University, North Carolina State University, and Kiel University (Dunbar, Dehn, and Leventer 1984; Dunbar et al. 1985). Vertical flux samples were collected with sediment traps deployed by Rice University (Dunbar 1984), Kiel University (Futterer et al. 1984), and Victoria University of Wellington (Pyne 1984). Organic carbon contents were determined by either LECO carbon analyzer or Perkin Elmer CHN analyzer. Biogenic silica content was measured by a silica dissolution technique modified from DeMaster (1981). Sediments from the Ross Sea are enriched in biogenic silica (up to 45 percent by weight) relative to sediments from the Bransfield Strait region (maximum opal content: 10 to 20 percent). Organic carbon contents approach 2 percent in both areas. These antarctic shelf sediments are greatly depleted in organic carbon relative to both modern and ancient siliceous deposits from low- and mid-latitude upwelling areas (table). We have attributed this trend to more efficient degradation of organic carbon relative to silica dissolution in the cold, welloxygenated waters of the antarctic shelf (Dunbar et al. 1984, 1985). Smith and Nelson (1985) have reported the presence of an ice-edge phytoplankton bloom with an anomalously low organic carbon/biogenic silica ratio, in agreement with previous observations which show a decrease in the organic carbon/ biogenic silica ratio of near-surface particulate matter in a transect from north to south across the Polar Front (Suess and Un gerer 1981). Thus, the low carbon signature of antarctic shelf siliceous sediments may partially reflect a primary input signal. Figure 1 shows flux and composition variations versus depth for two sediment trap experiments. The Bransfield Strait experiment (figure 1A) used traps similar to those of Zeitschel, Uhlmann, and Diekmann (1978) deployed on a single mooring in King George Basin under open water conditions dunn November and December 1983 (Futterer et al. 1984). The Gra nite Harbour (southwestern Ross Sea) samples (figure 1B) wer acquired from sediment traps similar in design to those o Soutar (Dymond et al. 1981) deployed at separate location within and adjacent to an 800-meter-deep basin beneath th annual sea ice from October to December 1983 (Pyne 1984). Bot experiments show an increase in total flux with depth. Tot 1 fluxes are generally higher in the Bransfield Strait although direct comparison is not possible because of differences in sediment-trap design. Opal content (weight percent biogenically produced silica) and opal flux (downward flux of biogenic silica) decrease with depth in the Bransfield Strait samples. Although zooplankton fecal pellets were important components of all samples from this location, pellet fluxes were highest (greater than 250,000 pellets per square meter per day) at depths shallower than 600 meters. Pellet settling velocities ranged from 200 to 400 meters per day and were generally higher in the deeper trap samples. Because surface-water productivity in the Bransfield Strait increased dramatically during the 18-day experiment (von ANTARCTIC JOURNAL
Bodungen personal communication), we attribute these trends to an episode of pellet production followed by fractionation via settling within the water column and some pellet disaggregation. Dilution of biogenic phases by terrigenous detritus occurs in the mid and lower portions of the water column and results in an increase in total flux. With increasing depth, the material in vertical transit becomes compositionally more similar to the basin surface sediments (figure 2). Approximate organic carbon/biogenic silica weight ratio for antarctic surface water particulate phasesa, antarctic sediment trap samples, and sediment samples.b
Location
silica ratios (table). Organic carbon preservation is enhanced by the high rate of supply of terrigenous material in this lower latitude antarctic setting as well as the effects of pelletization and efficient transport to the seafloor. The process operating in the Ross Sea appears to be more a reduction in organic carbon content to form sediments with very low organic carbonlbiogenic silica ratios. Dilution by terrigenous phases occurs but is of lesser importance than in the Bransfield Strait. Such a transformation can be achieved through extensive winnowing and transport during which the oxidation of organic carbon outpaces the dissolution of biogenic silica. Reworking of biogenic material in the Ross Sea is facilitated by the decreased importance of zooplankton pellet transport and presumed lower settling velocities of water-column particulates.
Weight ratio organic carbon/ biogenic silica
TOTAL FLUX
A Mg-2 -1 Near Surface particulate phases North of Polar Front South of Polar Front Ross Sea ice edge Sediment trap samples Ross Sea Bransfield Strait Sediments (> 10% biogenic silica) Surface sediments Ross Sea Bransfield Strait Upwelling areas Peru California Southwestern Africa Monterey Formation a b
d
2/1 1/1 1/3 to 1/4 1/4 to 1/8 1/8 to 1/16
0 2000 4000
0 25 50
75
I I I
1/20 to 1/30 1/10 to 1/13 1/2 to 1/4 1/1 to 1/3 1/1 to 1/4 1/2 to 1/8
In contrast to the Bransfield Strait results, samples from Granite Harbour show an increase in both opal concentration and flux with depth. Pellets were not common components of the trapped sediment and accounted for less than 10 percent of the flux to all traps. Biogenic phases apparently settled as undigested aggregates of organic opaline debris. Since the opaline flux is comprised mainly of diatom tests, the increase below 400 meters must be due to lateral transport of material winnowed from the water column or seafloor either locally or from other areas of the Ross Sea. The increase in opal concentration to nearly 40 percent attests to the ease with which these lowdensity biogenic phases are transported and the small amount of terrigenous input from the continent in this very high-latitude setting. Figure 2 shows the concentrations of opal and organic carbon n trap samples and surface sediments from both the Bransfield trait and southern Ross Sea. We have also included data from ndividual sediment traps previously deployed both in the ransfield Strait and, for 1 year, adjacent to the Ross Ice Shelf in he central Ross Sea (Dunbar 1984). In the Bransfield Strait, the asin sediment can be produced by diluting biogenic material roduced in shallow water with terrigenous material in the ater column or at the seafloor. Basin sediments and particulate atter in vertical transit have similar organic carbon/biogenic
OPAL FLUX -1 Mg m 2 d 0 1000 2000 I I
500 DEPTH (m)
1000
Suess and Ungerer 1981; Smith and Nelson 1985. Donegan and Schrader 1981; Bremner 1983; Reimers and Suess 1983; Dunbar 1984.
1,985 REVIEW
0
WT. % OPAL
I.
1500
(i
2000
TOTAL FLUX
B mgm2d1 0
0 500 1000
200 DEPTH
••. •
(m)
OPAL FLUX
WT. % OPAL Mg m 2 d1 0 20 40 0 100 200
.t
I I
I.
400 • 600 lim
I
505 •
II
Figure 1. Total flux, weight percentage biogenic silica, and flux of biogenic silica (A) to traps deployed on a single mooring in the Bransfield Strait in November and December 1983 and (B) to traps deployed on multiple moorings in Granite Harbour from October to December 1983. ('mg m 2d 1 " denotes "milligrams per square meter per day:' "m" denotes "meter:')
This work was supported by National Science Foundation grants DPP 83-12486 and INT 83-14541 to Robert B. Dunbar, a grant from the Deutsch Forschungsgemeinschaft to Gerald Wefer and a grant from Victoria University of Wellington to Anthony J . Macpherson. 99
70
PENINSULA SEDIMENT TRAPS • /
60
C,' CO
Q 40
I'
ca 30
Cj
20 10
I' ()
0 0
/c// 0 0 c0/ •
IA.
00
ROSS SEA SEDIMENT TRAPS
0
0 I_I'A I I I I I 0 1 2 3 4 5 6 7 8 WT. % ORGANIC CARBON Figure 2. Weight percentage ("WT%") organic carbon vs. weight percentage biogenic silica for surface sediments of the Bransfield Strait and Ross Sea and sediment-trap samples from Granite Harbour and the central Ross Sea (squares) and the Bransfield Strait (solid circles).
References Bremner, J.M. 1983. Biogenic sediments on the South West African (Namibian) continental margin. In J. Thiede and E. Suess (Eds.), Coastal upwelling: Its sediment record, Part B. New York: Plenum Press. DeMaster, D.J. 1981. The supply and accumulation of silica in the marine environment. Geochimica et Cosmochimica Acta, 45, 1715-1732.
Suspended particulate matter in antarctic coastal waters A.R. LEVENTER and R.B. DUNBAR Department of Geology Rice University Houston, Texas 77251
Suspended particulate matter plays an important role in maintaining chemical and biological gradients in the ocean. Its composition and concentration reflect dynamic water-column processes such as primary production in surface waters, dissolution and degradation at depth, and vertical and lateral parti100
Donegan, D., and H. Schrader. 1981. Modern analogs of the Miocene diatomaceous Monterey Shale of California: Evidence from sedimentologic and micropaleontologic study. In R.E. Garrison, R.G. Douglas, K.E. Pisciotto, G.M. Isaacs, and J.C. Ingle (Eds.), The Monterey Formation and related siliceous rocks of California. Los Angeles: Society of Economic Paleontologists and Mineralogists, Pacific Section. Dunbar, R.B. 1984. Sediment trap experiments on the Antarctic continental margin. Antarctic Journal of the U.S., 19(5), 70 - 71. Dunbar, R.B., J.B. Anderson, E.W. Domack, and S.S. Jacobs. 1985. Oceanographic influences on sedimentation along the antarctic conti nental shelf. In S.S. Jacobs (Ed.), Oceanology of the Antarctic Shelf (Antarctic Research Series, Vol 43.) Washington, D.C.: American Geophysical Union. Dunbar, R. B., M. Dehn, and A. Leventer. 1984. Distribution of biogenic components in surface sediments from the antarctic continental shelf. Antarctic Journal of the U.S., 19(5), 126 - 128. Dymond, J . , K. Fischer, M. Clauson, R. Cobler, W. Gardner, M.J. Richardson, W. Berger, A. Soutar, and R. Dunbar. 1981. A sediment trap intercomparison study in the Santa Barbara Basin. Earth and Planetary Science Letters, 53, 409 - 418. Futterer, D., and scientific crew (ANTARKTIS-I1). 1984. Report on polar research. Bremerhaven: Alfred-Wegener-Institut für Polarforschung. (In German.)
Pyne, A. 1984. Immediate report, Victoria University of Wellington Antarctic expedition 28, 1983 - 1984. Wellington: Antarctic Re-
search Centre, Victoria University. Reimers, C.E., and E. Suess. 1983. Spatial and temporal patterns of organic matter accumulation on the Peru continental margin. In J. Thiede and E. Suess (Eds.), Coastal upwelling: Its sediment record, Part B. New York: Plenum Press. Smith, W.O., and D.M. Nelson. 1985. Phytoplankton bloom produced by a receding ice edge in the Ross Sea: Spatial coherence with the density field. Science, 227, 163 - 166. Suess, E., and A. Ungerer. 1981. Element and phase composition of particulate matter from the circumpolar current between New Zealand and Antarctica. Oceanologica Acta, 4, 151 160. Sullivan, C.W., A.C. Palmisano, S. Kottmeier, and R. Moe. 1982. Development of the sea ice microbial community in McMurdo Sound. Antarctic Journal of the U. S., 17(5), 155- 157. von Bodungen, B. 1984. Personal communication. Zeitschel, B., L. Uhlmann, and P. Diekmann. 1978. A new multisample sediment trap. Marine Biology, 45, 285 - 288.
cle transport (Biscaye and Eittreim 1977; Bishop et al. 1977; Lal and Lerman 1973). Because much of the ocean's bottom water originates on the antarctic margin, variations in particulatematter supply and interaction with the southern-ocean water column may influence global ocean chemistry significantly. Suspended particulate matter was collected by filtration of I to 2 liters of seawater (from Niskin bottle samples) through preweighed 0.4-micrometer Nuclepore membrane filters. Filters were dried in a dessicator and reweighed as soon as possible. Based on processing of "blank" filters, weighing precision for our samples is 20 micrograms. Areas studied include transect parallel to the edge of the Ross Ice Shelf (February 1983, figure 1), McMurdo Sound (October to November 1984, figur 2), and the Antarctic Peninsula region (November and De cember 1983, figure 3). The Ross Ice Shelf and Antarctic Penin sula samples were collected in areas relatively free of sea ice The McMurdo Sound samples were collected from beneat annual fast ice. ANTARCTIC JOURNAL
R.B. DUNBAR Department of Geology Rice University Houston, Texas 77251
A.J. MACPHERSON Antarctic Research Centre Victoria University of Wellington Wellington, New Zealand
G. WEFER Geologisches Institut Universitdt Kid Kiel, Federal Republic of Germany
A recent proliferation of moored sediment-trap experiments and surface sediment collection has allowed us to begin to characterize the complex water column and seafloor processes which govern sedimentation on the antarctic continental shelf. Each summer, as the annual sea ice breaks up and melts, emerging areas of open water are sites of episodic algal blooms and the production of large amounts of particulate matter enriched in opal and organic carbon. Biogenic phases are also produced within the basal portion of the sea ice (Sullivan et al. 1982). Only a fraction of the particulate matter produced in the photic zone actually accumulates in shelf deposits, because these phases may be readily dissolved, degraded, or winnowed both in the water column and at the seafloor. Here we compare vertical fluxes and concentrations of biogenic components in the water column with the composition of sediments at the seafloor of the Antarctic Peninsula and the southern Ross Sea. These areas appear to represent two end-member environments in terms of particle transport, recycling, and deposition. Our ultimate goal is to construct a quantitative model for the production or input of both terrigenous and biogenic sedimentary components and their subsequent modification within the water column or at the seafloor. Such models are prerequisites for retrospective studies involving shelf sediments and also provide important insight into nutrient element recycling in this unique environment. 98
Surface sediment data is derived from samples collected by Rice University, North Carolina State University, and Kiel University (Dunbar, Dehn, and Leventer 1984; Dunbar et al. 1985). Vertical flux samples were collected with sediment traps deployed by Rice University (Dunbar 1984), Kiel University (Futterer et al. 1984), and Victoria University of Wellington (Pyne 1984). Organic carbon contents were determined by either LECO carbon analyzer or Perkin Elmer CHN analyzer. Biogenic silica content was measured by a silica dissolution technique modified from DeMaster (1981). Sediments from the Ross Sea are enriched in biogenic silica (up to 45 percent by weight) relative to sediments from the Bransfield Strait region (maximum opal content: 10 to 20 percent). Organic carbon contents approach 2 percent in both areas. These antarctic shelf sediments are greatly depleted in organic carbon relative to both modern and ancient siliceous deposits from low- and mid-latitude upwelling areas (table). We have attributed this trend to more efficient degradation of organic carbon relative to silica dissolution in the cold, welloxygenated waters of the antarctic shelf (Dunbar et al. 1984, 1985). Smith and Nelson (1985) have reported the presence of an ice-edge phytoplankton bloom with an anomalously low organic carbon/biogenic silica ratio, in agreement with previous observations which show a decrease in the organic carbon/ biogenic silica ratio of near-surface particulate matter in a transect from north to south across the Polar Front (Suess and Un gerer 1981). Thus, the low carbon signature of antarctic shelf siliceous sediments may partially reflect a primary input signal. Figure 1 shows flux and composition variations versus depth for two sediment trap experiments. The Bransfield Strait experiment (figure 1A) used traps similar to those of Zeitschel, Uhlmann, and Diekmann (1978) deployed on a single mooring in King George Basin under open water conditions dunn November and December 1983 (Futterer et al. 1984). The Gra nite Harbour (southwestern Ross Sea) samples (figure 1B) wer acquired from sediment traps similar in design to those o Soutar (Dymond et al. 1981) deployed at separate location within and adjacent to an 800-meter-deep basin beneath th annual sea ice from October to December 1983 (Pyne 1984). Bot experiments show an increase in total flux with depth. Tot 1 fluxes are generally higher in the Bransfield Strait although direct comparison is not possible because of differences in sediment-trap design. Opal content (weight percent biogenically produced silica) and opal flux (downward flux of biogenic silica) decrease with depth in the Bransfield Strait samples. Although zooplankton fecal pellets were important components of all samples from this location, pellet fluxes were highest (greater than 250,000 pellets per square meter per day) at depths shallower than 600 meters. Pellet settling velocities ranged from 200 to 400 meters per day and were generally higher in the deeper trap samples. Because surface-water productivity in the Bransfield Strait increased dramatically during the 18-day experiment (von ANTARCTIC JOURNAL
Bodungen personal communication), we attribute these trends to an episode of pellet production followed by fractionation via settling within the water column and some pellet disaggregation. Dilution of biogenic phases by terrigenous detritus occurs in the mid and lower portions of the water column and results in an increase in total flux. With increasing depth, the material in vertical transit becomes compositionally more similar to the basin surface sediments (figure 2). Approximate organic carbon/biogenic silica weight ratio for antarctic surface water particulate phasesa, antarctic sediment trap samples, and sediment samples.b
Location
silica ratios (table). Organic carbon preservation is enhanced by the high rate of supply of terrigenous material in this lower latitude antarctic setting as well as the effects of pelletization and efficient transport to the seafloor. The process operating in the Ross Sea appears to be more a reduction in organic carbon content to form sediments with very low organic carbonlbiogenic silica ratios. Dilution by terrigenous phases occurs but is of lesser importance than in the Bransfield Strait. Such a transformation can be achieved through extensive winnowing and transport during which the oxidation of organic carbon outpaces the dissolution of biogenic silica. Reworking of biogenic material in the Ross Sea is facilitated by the decreased importance of zooplankton pellet transport and presumed lower settling velocities of water-column particulates.
Weight ratio organic carbon/ biogenic silica
TOTAL FLUX
A Mg-2 -1 Near Surface particulate phases North of Polar Front South of Polar Front Ross Sea ice edge Sediment trap samples Ross Sea Bransfield Strait Sediments (> 10% biogenic silica) Surface sediments Ross Sea Bransfield Strait Upwelling areas Peru California Southwestern Africa Monterey Formation a b
d
2/1 1/1 1/3 to 1/4 1/4 to 1/8 1/8 to 1/16
0 2000 4000
0 25 50
75
I I I
1/20 to 1/30 1/10 to 1/13 1/2 to 1/4 1/1 to 1/3 1/1 to 1/4 1/2 to 1/8
In contrast to the Bransfield Strait results, samples from Granite Harbour show an increase in both opal concentration and flux with depth. Pellets were not common components of the trapped sediment and accounted for less than 10 percent of the flux to all traps. Biogenic phases apparently settled as undigested aggregates of organic opaline debris. Since the opaline flux is comprised mainly of diatom tests, the increase below 400 meters must be due to lateral transport of material winnowed from the water column or seafloor either locally or from other areas of the Ross Sea. The increase in opal concentration to nearly 40 percent attests to the ease with which these lowdensity biogenic phases are transported and the small amount of terrigenous input from the continent in this very high-latitude setting. Figure 2 shows the concentrations of opal and organic carbon n trap samples and surface sediments from both the Bransfield trait and southern Ross Sea. We have also included data from ndividual sediment traps previously deployed both in the ransfield Strait and, for 1 year, adjacent to the Ross Ice Shelf in he central Ross Sea (Dunbar 1984). In the Bransfield Strait, the asin sediment can be produced by diluting biogenic material roduced in shallow water with terrigenous material in the ater column or at the seafloor. Basin sediments and particulate atter in vertical transit have similar organic carbon/biogenic
OPAL FLUX -1 Mg m 2 d 0 1000 2000 I I
500 DEPTH (m)
1000
Suess and Ungerer 1981; Smith and Nelson 1985. Donegan and Schrader 1981; Bremner 1983; Reimers and Suess 1983; Dunbar 1984.
1,985 REVIEW
0
WT. % OPAL
I.
1500
(i
2000
TOTAL FLUX
B mgm2d1 0
0 500 1000
200 DEPTH
••. •
(m)
OPAL FLUX
WT. % OPAL Mg m 2 d1 0 20 40 0 100 200
.t
I I
I.
400 • 600 lim
I
505 •
II
Figure 1. Total flux, weight percentage biogenic silica, and flux of biogenic silica (A) to traps deployed on a single mooring in the Bransfield Strait in November and December 1983 and (B) to traps deployed on multiple moorings in Granite Harbour from October to December 1983. ('mg m 2d 1 " denotes "milligrams per square meter per day:' "m" denotes "meter:')
This work was supported by National Science Foundation grants DPP 83-12486 and INT 83-14541 to Robert B. Dunbar, a grant from the Deutsch Forschungsgemeinschaft to Gerald Wefer and a grant from Victoria University of Wellington to Anthony J . Macpherson. 99
70
PENINSULA SEDIMENT TRAPS • /
60
C,' CO
Q 40
I'
ca 30
Cj
20 10
I' ()
0 0
/c// 0 0 c0/ •
IA.
00
ROSS SEA SEDIMENT TRAPS
0
0 I_I'A I I I I I 0 1 2 3 4 5 6 7 8 WT. % ORGANIC CARBON Figure 2. Weight percentage ("WT%") organic carbon vs. weight percentage biogenic silica for surface sediments of the Bransfield Strait and Ross Sea and sediment-trap samples from Granite Harbour and the central Ross Sea (squares) and the Bransfield Strait (solid circles).
References Bremner, J.M. 1983. Biogenic sediments on the South West African (Namibian) continental margin. In J. Thiede and E. Suess (Eds.), Coastal upwelling: Its sediment record, Part B. New York: Plenum Press. DeMaster, D.J. 1981. The supply and accumulation of silica in the marine environment. Geochimica et Cosmochimica Acta, 45, 1715-1732.
Suspended particulate matter in antarctic coastal waters A.R. LEVENTER and R.B. DUNBAR Department of Geology Rice University Houston, Texas 77251
Suspended particulate matter plays an important role in maintaining chemical and biological gradients in the ocean. Its composition and concentration reflect dynamic water-column processes such as primary production in surface waters, dissolution and degradation at depth, and vertical and lateral parti100
Donegan, D., and H. Schrader. 1981. Modern analogs of the Miocene diatomaceous Monterey Shale of California: Evidence from sedimentologic and micropaleontologic study. In R.E. Garrison, R.G. Douglas, K.E. Pisciotto, G.M. Isaacs, and J.C. Ingle (Eds.), The Monterey Formation and related siliceous rocks of California. Los Angeles: Society of Economic Paleontologists and Mineralogists, Pacific Section. Dunbar, R.B. 1984. Sediment trap experiments on the Antarctic continental margin. Antarctic Journal of the U.S., 19(5), 70 - 71. Dunbar, R.B., J.B. Anderson, E.W. Domack, and S.S. Jacobs. 1985. Oceanographic influences on sedimentation along the antarctic conti nental shelf. In S.S. Jacobs (Ed.), Oceanology of the Antarctic Shelf (Antarctic Research Series, Vol 43.) Washington, D.C.: American Geophysical Union. Dunbar, R. B., M. Dehn, and A. Leventer. 1984. Distribution of biogenic components in surface sediments from the antarctic continental shelf. Antarctic Journal of the U.S., 19(5), 126 - 128. Dymond, J . , K. Fischer, M. Clauson, R. Cobler, W. Gardner, M.J. Richardson, W. Berger, A. Soutar, and R. Dunbar. 1981. A sediment trap intercomparison study in the Santa Barbara Basin. Earth and Planetary Science Letters, 53, 409 - 418. Futterer, D., and scientific crew (ANTARKTIS-I1). 1984. Report on polar research. Bremerhaven: Alfred-Wegener-Institut für Polarforschung. (In German.)
Pyne, A. 1984. Immediate report, Victoria University of Wellington Antarctic expedition 28, 1983 - 1984. Wellington: Antarctic Re-
search Centre, Victoria University. Reimers, C.E., and E. Suess. 1983. Spatial and temporal patterns of organic matter accumulation on the Peru continental margin. In J. Thiede and E. Suess (Eds.), Coastal upwelling: Its sediment record, Part B. New York: Plenum Press. Smith, W.O., and D.M. Nelson. 1985. Phytoplankton bloom produced by a receding ice edge in the Ross Sea: Spatial coherence with the density field. Science, 227, 163 - 166. Suess, E., and A. Ungerer. 1981. Element and phase composition of particulate matter from the circumpolar current between New Zealand and Antarctica. Oceanologica Acta, 4, 151 160. Sullivan, C.W., A.C. Palmisano, S. Kottmeier, and R. Moe. 1982. Development of the sea ice microbial community in McMurdo Sound. Antarctic Journal of the U. S., 17(5), 155- 157. von Bodungen, B. 1984. Personal communication. Zeitschel, B., L. Uhlmann, and P. Diekmann. 1978. A new multisample sediment trap. Marine Biology, 45, 285 - 288.
cle transport (Biscaye and Eittreim 1977; Bishop et al. 1977; Lal and Lerman 1973). Because much of the ocean's bottom water originates on the antarctic margin, variations in particulatematter supply and interaction with the southern-ocean water column may influence global ocean chemistry significantly. Suspended particulate matter was collected by filtration of I to 2 liters of seawater (from Niskin bottle samples) through preweighed 0.4-micrometer Nuclepore membrane filters. Filters were dried in a dessicator and reweighed as soon as possible. Based on processing of "blank" filters, weighing precision for our samples is 20 micrograms. Areas studied include transect parallel to the edge of the Ross Ice Shelf (February 1983, figure 1), McMurdo Sound (October to November 1984, figur 2), and the Antarctic Peninsula region (November and De cember 1983, figure 3). The Ross Ice Shelf and Antarctic Penin sula samples were collected in areas relatively free of sea ice The McMurdo Sound samples were collected from beneat annual fast ice. ANTARCTIC JOURNAL
