Antarctic Marine Sediments Research Articles

Determination of trace metals complexed with humic acids in Antarctic marine sediments

ABSTRACTHumic acids play an important role in the solubility, mobility and accumulation of trace metals in marine environment. Nine sediment samples collected in Terranova Bay, Antarctica, have been treated in order to extract the metal—humic acid complexes. The concentration of humic acids was measured with a spectrophotometric method while five trace metals, Cr, Cu, Mn, Ni and Zn were determined by means of an inductively coupled plasma atomic emission spectrometer (ICP-AES). The content of these metals measured in the humic fraction in the sediment, except for Mn, showed a significant correlation to the amount of humic acids. Copper appeared to be the most accumulative element in humic acids.

Analysis of Antarctic Marine Sediment by Inductively Coupled Plasma Atomic Emission and Total Reflection X-Ray Fluorescence Spectrometry

Microwave digestion and extraction techniques were developed for elemental analysis of Antarctic marine sediment by inductively coupled plasma atomic emission spectrometry (ICP-AES) and total reflection X-ray fluorescence (TXRF) spectrometry. These sample preparation techniques were tested by analyzing river sediment certified reference material (BCR-320). Concentrations of Al, Fe, Mn, Zn, Cr, Co, and Cu were determined by ICP-AES after microwave digestion of sediment in a mixture of HF + HNO3+ HCl + H3BO3with acceptable accuracy. Due to the strong matrix effect and spectral interference, Cd, Sn, Pb, Ni, and As cannot be determined using ICP-AES; however, the proposed microwave extraction procedure appears to be suitable for measurement of Zn, Cu, Pb, Ni, and As using TXRF spectrometry.

Sedimentary Humic Acids in the Continental Margin of the Ross Sea (ANTARCTICA)

Humic acids (HA) extracted from Antarctic marine sediments were characterized using different techniques (FTIR, NMR, Thermogravimetry, Elemental Analysis and Ionic Exchange Chromatography). Antarctic sedimentary HA show a greater content of nitrogen and a predominant aliphatic nature when compared with data reported in the literature for non Antarctic HA samples. Some differences in the structures, such as the presence of aromatic carbon rings, carbohydrates, fatty acids, etc., have been observed, as a function of sampling zones. The differences are probably due to a different humification process, possibly depending on different trends of temperature and salinity measured down to the water column.

Humic Compounds in Seawater and Marine Sediments from Antarctica

Abstract This paper reports the results of various types of analysis and physico-chemical characterization of several samples of humic compounds extracted from Antarctic seawater and marine sediments. Several features of Antarctic humic compounds are evidenced. In seawater only fulvic acids are present. Fluorescence spectra of filtered seawater are similar to those of aquatic fulvics extracted from the same location. In sediments, only humic acids are present; they are characterized by a high aliphatic fraction and large quantities of aminoacids, as shown by NMR and IR. The particulate is a mixture of inorganic and organic matter, the latter consisting of proteinaceous material, carbohydrates and lipids.

Non-destructive porosity determinations of antarctic marine sediments derived from resistivity measurements with an inductive method

The fractional porosity of marine sediments is one of the fundamental index properties of rocks. For the determination of porosity a nondestructive, inductive method was used on unsplit sediment cores. The results were compared with galvanically measured resistivities using a miniature Wenner array on split cores. The measurements agree well except for cores with high clay content where measurement frequency related effects cause a resistivity difference of about 10%. Porosities were derived from resistivities using a published resistivity-porosity relationship by Boyce (1968) and compared with sample porosities. A comparison of both data sets shows good agreement.

Hydrogenation behaviour of two highly branched C 25 dienes from Antarctic marine sediments

Hydrogenation behaviour of two highly branched C 25 dienes from Antarctic marine sediments

Chitinolytic bacteria and chitin mineralization in the marine waters and sediments along the Antartic Peninsula

Chitinolytic bacteria were enumerated and isolated from marine waters and sediments along the highly productive Antarctic Peninsula. Chitinolytic bacteria were found in low concentrations (approximately 1 cell per ml) in the water column and at much higher levels in marine surface sediments (104–105 per g). The predominant chitinolytic bacteria isolated from the water column were identified as psychrophilic Vibrio spp. Rates of chitin mineralization were measured by collection of 14CO2 respired from 14C-labeled chitin synthesized from chitosan and [1-14C]acetic anhydride. Chitin mineralization rates were extremely low in the marine waters analyzed (0.00085–0.0019% of the added label respired in 48 h) and appreciably higher in the marine sediments (0.0039–0.01% per 48 h), suggesting that the sediments are much more important in chitin degradation. Such low mineralization rates suggest that chitin may be accumulating in Antarctic marine sediments, though animals may also play an important role in chitin degradation.

Coprostanols in Antarctic marine sediments: A biomarker for marine mammals and not human pollution

The first analysis of sterols in Antarctic marine sediment cores (Bransfield Strait and McMurdo Sound) is reported here. The isolated sterols in the sediments from Bransfield Strait are comprised mainly of dinosterol (4α,23,24-trimethyl-5αcholest-22-en-3β-ol), coprostanol (5β-cholestan-3β-ol) and epicoprostanol (5β-cholestan-3α-ol) and trace amounts of cholesterol (cholest-5-en-3β-ol). The sediment cores of McMurdo Sound also contain small quantities of coprostanols in addition to large amounts of marine sterols. Dinosterol is a known dinoflagellate chemical marker, whereas coprostanols are currently being used as tracers for sewage contamination. However, sterol composition in Antarctic sediments is expected to be atypical of sewage input and probably different from those of temperate and tropical zones. The coprostanols must therefore arise from the feces of marine mammals, most probably whales which use the region for feeding and spawning. Based on the results of this study, caution should be exercised in the use of coprostanol to estimate the amount of sewage-derived organic matter transported away from impacted coastal areas.

Analysis of aliphatic and aromatic hydrocarbons in Antarctic marine sediment layers

THE presence of both paraffinic and polycyclic aromatic hydrocarbons (PAH) in sediments and soils from the Northern Hemisphere has been well documented1–5. Paraffinic hydrocarbons are generally assumed to be derived predominantly from land plants6 but the sources of PAH are still uncertain7. However, the general consensus seems to be that they are from the fallout of airborne combustion products3. Industrialised areas have higher PAH loadings5 whilst dated cores from areas with a history of increasing industrialisation show a concomitant increase in total PAH loads but no great change in the relative proportions of individual components. Considerable interest is also vested in the fate of hydrocarbons once deposited in sediments6. With mineral resources being depleted in more accessible areas, those of remote regions (including polar ones) are being considered. But little is yet known of the effects that near-zero temperatures may have on the rate of biochemical or chemical alteration of hydrocarbons such as those found in petroleum. We report here our attempts to test the ‘combustion source hypothesis’ and to investigate the fate of hydrocarbons in sediments from a remote sub-Antarctic island with a well-documented history of localised industrial pollution8 spanning the period 1904–65. Only very minor local inputs of pollutant hydrocarbons are likely to have occurred on either side of these dates.

Isolation and Identification of Photosynthetic Bacteria (Rhodospirillaceae) from Antarctic Marine and Freshwater Sediments

Sediment samples obtained from three freshwater lakes and off‐shore coastal marine waters on Signy Island, South Orkney Islands, Antarctica have been inoculated into selective enrichment media for purple non‐sulphur bacteria (Rhodospirillaceae). From the freshwater sediments strains of Rhodopseudomonas sphaeroides (1), Rhodopseudomonas palustris (1), Rhodospirillum fulvum (1), Rhodospirillum molischanum (1) and Rhodomicrobium vannielii (3) have been isolated. The only purple non‐sulphur bacteria obtained from Lake 10 (Amos lake) were strains of Rhodomicrobium vannielii which were able to tolerate hydrogen sulphide (up to 0.04% w/v) found in this lake. Growth of all the other isolates is inhibited by the presence of hydrogen sulphide. Marine sediments yielded strains of Rhodopseudomonas palustris and Rhodomicrobium vannielii. All the isolates grow optimally at temperatures between 25 and 30 °C. mean generation times vary between 8 and 10.7 h depending on species. There is no evidence of cold adaptation in any of the strains studied.

Geochemistry of Antarctic pelagic sediments

Information of the chemistry of Recent Antarctic glacial marine sediments and the distribution patterns related thereto is extremely limited. Much of the data are influenced by those conditions of sedimentation peculiar to the Antarctic regions. Unlike other areas of sediment deposition, most of the sedimentary material deposited south of 60°S accumulates away from the Antarctic coast in regions of maximum deposition by melting icebergs. For the major chemical components (SiO 2, CaCO 3, MgCO 3) no distinctive and consistent geographical distribution other than latitudinal is evident. Analysis of 14 cores (80 samples) from the Ross, Bellingshausen and Amundsen Seas indicates sharp geographical differences in trace-element (Cr, Ni, Co, V, Cu, Mn, Ti, Al, Mo, W, Pb, Zn) content. Molybdenum was invariably less than 20 ppm, Pb less than 50 ppm, and Zn and W were less than 200 ppm. For glacial marine sediments as a type, the elements Cr, Ni, Ti, Fe and Al are deficient when compared to crustal abundances. V, Cu and Fe were especially high in Amundsen Sea sediments (average V = 240 ppm, Cu = 185 ppm, Fe = 4.1 per cent). Samples from Bellingshausen Sea, as a group, are quite deficient in Cr, Ni and Mn. Values for trace element content of Ross Sea sediments are intermediate between those of Bellingshausen and Amundsen Sea sediments. Study of figures for absolute concentration in the cores from the different areas shows sharp breaks in the elemental depth profiles. These breaks are strongly suggestive of past changes in both sedimentation rates and climatological conditions in these regions. In terms of different metal-ion ratios ( Mn Fe , Mn Al , Cu Al , V Al , Cu Fe , Cr Al , Ni Al , Fe Al , Ti Al , Co Al , Ni Co , Cr V , Mn Ti and Fe Ti ) no strong intercore correlations were noted. Examination of all the data available clearly shows that, on the basis of trace element content, glacial marine sediments have a chemistry distinctly different from that of shelf, deep-sea carbonate and deep-sea clay sediments. Trace element criteria could be useful in identifying the presence of such glacial marine sediments (presently unrecognized) in the geologic column.