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The influence of bioturbation on physical, chemical and biological parameters in aquatic environments: a review
OLR(1986)33 (3)
F. General
deduced from measurements in the deep sea: to sell~et W.xafluecide and carbon tetrachiorlde. Atmos. Environ~ 19(9):1477-1484. On a time scale of several decades, an increase in the atmospheric burden of certain stable trace gases results in a characteristic oceanic depth profile for the concentration of the dissolved gas. If the atmosphere is the only source of the gas to the sea, the time delay inherent in its downward penetration from the surface results in a profile which decreases with depth. By referencing to compounds whose atmospheric histories are relatively well known, limits can be placed on the increase of a trace gas whose history is unknown. Data suggest that at least 50% of atmospheric CCI4 and CF4, which may have both natural and anthropogenic origins, is of recent anthropogenic origin. Mar. Biol. Assoc., The Laboratory, Citadel Hill, Plymouth PLI 2PB, UK.
F380. Advances in science, reviews (general interest) 86:1779 Boillot, G. and E.L. Winterer (and the Leg 103 shipboard scientific party.), 1985. Ocean Drilling Program. Evolution of a passive margin. Nature, Lond~ 317(6033): 115-116. ODP Leg 103, a transect of 5 sites with 14 drill holes at the seaward edge of the Galician margin, was planned to investigate the tectonic and sedimentary evolution of the seafloor between Newfoundland and Iberia. Listed among the principal discoveries are: (1) a ridge of mantle-type material near the oceanic/continental boundary; (2) a basement-type seismic reflector, which was in fact a Mesozoic shallow-water carbonate platform; (3) evidence of platform drowning, rapid subsidence, and faultblock tilting about 135 Myr, about 25 m.y. before formation of oceanic crust; (4) deposition of abundant terrigenous elastic to deep-water sediments from 130-115 Myr during early rifting; and (5) the seismic reflector marks the base of the sediments deposited during rifting and thus is not a boundary within the continental crust. Univ. P. et M. Curie, Paris, France. (hbf) 86:1780
Gribbin, John, 1985. New time scale for ice-age cycles. New Scient~ 107(1474):p.25. A 2083-m long core recovered from the Antarctic ice cap contains a continuous climate record of the past 150,000-160,000 yr (reaching beyond the most recent ice age, through the preceding interglacial to the end of the ice age before that). Results of analyses of the
257
core (presented in two recently published papers in Nature, 316) show a roughly 40,000 year cycle in temperature variations, perhaps related to changes in the Earth's orbit; support the theory that there was less atmospheric CO2 when the world was colder; and indicate that more ~°Be is laid down during colder epochs. (msg) 86:1781 Krantzberg, Gail, 1985. The influence of bioturbation on physical, chemical and biological lmrmneters in aquatic environments: a review. Environ. Pollut., (A)39(2):99-122. Benthic macroinvertebrates have been shown to affect sediment stratigraphy, particle size, porosity, shear strength, surface microtopography, oxygen penetration, Eh potential, and pH, changes which correlate with alterations in the physicochemical form distribution of trace elements and fluxes of N, P, Cu, Fe, I, Hg, Mn, Si, Zn, PCBs, and radioisotopes. The importance of considering particle mixing in aquatic studies including core dating, cycling, toxin remobilization, and surface burial is stressed. Inst. for Environmental Studies, Univ. of Toronto, Ont. M5S 1A4, Canada. (gsb) 86:1782 Nowell, A.R.M., I.N. McCave and C.D. Hollister, 1985. Contributions of HEBBLE to understanding marine sedimentation. Mar. Geol., 66(14):397-409. An evaluation of HEBBLE's early site-descriptive results and their implications for understanding marine sedimentological processes is presented. The project has shown that the largest bedforms demonstrate the least variance with time, whereas small-scale features display the greatest variability; the overall pattern, however, is a contour-parallel flow to the WSW. The disagreement over the depositional origin of longitudinal ripples is discussed in some detail. Biscayne et al.'s (1980) measurement of suspended particle concentrations as high as 12 grn-3 provides new understanding about the generation and properties of the nepheloid layer. Biological studies reveal surprising abundances of macrofauna, meiofauna, and bacteria, which may be of considerable importance for erosion phenomena. To the 2500 photographs already taken of the site, will be added time series of stereophotographs which can provide a height resolution better than 1 mm. Other major instrnmentation advances--acoustic stress sensors, BASS tripods, the Oregon State transmissometer (an optical sensor), and SEADUCT--should produce a wealth of significant data before the conclusion of the program in 1986. Sch. of
F. General
deduced from measurements in the deep sea: to sell~et W.xafluecide and carbon tetrachiorlde. Atmos. Environ~ 19(9):1477-1484. On a time scale of several decades, an increase in the atmospheric burden of certain stable trace gases results in a characteristic oceanic depth profile for the concentration of the dissolved gas. If the atmosphere is the only source of the gas to the sea, the time delay inherent in its downward penetration from the surface results in a profile which decreases with depth. By referencing to compounds whose atmospheric histories are relatively well known, limits can be placed on the increase of a trace gas whose history is unknown. Data suggest that at least 50% of atmospheric CCI4 and CF4, which may have both natural and anthropogenic origins, is of recent anthropogenic origin. Mar. Biol. Assoc., The Laboratory, Citadel Hill, Plymouth PLI 2PB, UK.
F380. Advances in science, reviews (general interest) 86:1779 Boillot, G. and E.L. Winterer (and the Leg 103 shipboard scientific party.), 1985. Ocean Drilling Program. Evolution of a passive margin. Nature, Lond~ 317(6033): 115-116. ODP Leg 103, a transect of 5 sites with 14 drill holes at the seaward edge of the Galician margin, was planned to investigate the tectonic and sedimentary evolution of the seafloor between Newfoundland and Iberia. Listed among the principal discoveries are: (1) a ridge of mantle-type material near the oceanic/continental boundary; (2) a basement-type seismic reflector, which was in fact a Mesozoic shallow-water carbonate platform; (3) evidence of platform drowning, rapid subsidence, and faultblock tilting about 135 Myr, about 25 m.y. before formation of oceanic crust; (4) deposition of abundant terrigenous elastic to deep-water sediments from 130-115 Myr during early rifting; and (5) the seismic reflector marks the base of the sediments deposited during rifting and thus is not a boundary within the continental crust. Univ. P. et M. Curie, Paris, France. (hbf) 86:1780
Gribbin, John, 1985. New time scale for ice-age cycles. New Scient~ 107(1474):p.25. A 2083-m long core recovered from the Antarctic ice cap contains a continuous climate record of the past 150,000-160,000 yr (reaching beyond the most recent ice age, through the preceding interglacial to the end of the ice age before that). Results of analyses of the
257
core (presented in two recently published papers in Nature, 316) show a roughly 40,000 year cycle in temperature variations, perhaps related to changes in the Earth's orbit; support the theory that there was less atmospheric CO2 when the world was colder; and indicate that more ~°Be is laid down during colder epochs. (msg) 86:1781 Krantzberg, Gail, 1985. The influence of bioturbation on physical, chemical and biological lmrmneters in aquatic environments: a review. Environ. Pollut., (A)39(2):99-122. Benthic macroinvertebrates have been shown to affect sediment stratigraphy, particle size, porosity, shear strength, surface microtopography, oxygen penetration, Eh potential, and pH, changes which correlate with alterations in the physicochemical form distribution of trace elements and fluxes of N, P, Cu, Fe, I, Hg, Mn, Si, Zn, PCBs, and radioisotopes. The importance of considering particle mixing in aquatic studies including core dating, cycling, toxin remobilization, and surface burial is stressed. Inst. for Environmental Studies, Univ. of Toronto, Ont. M5S 1A4, Canada. (gsb) 86:1782 Nowell, A.R.M., I.N. McCave and C.D. Hollister, 1985. Contributions of HEBBLE to understanding marine sedimentation. Mar. Geol., 66(14):397-409. An evaluation of HEBBLE's early site-descriptive results and their implications for understanding marine sedimentological processes is presented. The project has shown that the largest bedforms demonstrate the least variance with time, whereas small-scale features display the greatest variability; the overall pattern, however, is a contour-parallel flow to the WSW. The disagreement over the depositional origin of longitudinal ripples is discussed in some detail. Biscayne et al.'s (1980) measurement of suspended particle concentrations as high as 12 grn-3 provides new understanding about the generation and properties of the nepheloid layer. Biological studies reveal surprising abundances of macrofauna, meiofauna, and bacteria, which may be of considerable importance for erosion phenomena. To the 2500 photographs already taken of the site, will be added time series of stereophotographs which can provide a height resolution better than 1 mm. Other major instrnmentation advances--acoustic stress sensors, BASS tripods, the Oregon State transmissometer (an optical sensor), and SEADUCT--should produce a wealth of significant data before the conclusion of the program in 1986. Sch. of