Matter In Surface Waters Research Articles

Tungsten in north pacific waters

Tungsten in oceanic waters has only been analysed in a few coastal areas. Here, we report the first tungsten depth profiles in oceanic waters. Tungsten concentration in the north Pacific is constant at 53–60 pmol l −1 (normalized to a salinity of 35‰) from the surface to the bottom. Similar vertical profiles of tungsten and molybdenum probably result from the fact that both elements are hardly adsorbed at all onto organisms and particulate organic matter in surface waters. However, although the crustal abundance of tungsten and molybdenum are nearly equal, the concentration of tungsten is ∼ 1 1800 of that of molybdenum in oceanic waters. This indicates that tungsten is removed from seawater much more rapidly than molybdenum, by adsorption onto ferric hydroxide, manganese oxide and clay minerals.

Particulate aluminium, iron and manganese chemistry at the deep Atlantic boundary layer

Scanning electron microscopy and instrumental neutron activation analyses of filtered suspended matter from the Atlantic Ocean show that particulate aluminium (Al p) is a sensitive measure of bottom derived or resuspended material. The proportion of Al p in suspended particulate matter (SPM) increases slightly between surface and intermediate depths but shows large and steady increases in deep waters with approach to the bottom. Fe p/Al p andMn p/Al p ratios are always higher than the crustal ratios throughout the water column. We show that the processes which can explain such enrichments are different for particulate matter in surface waters (scavenging, incorporation in biogenic particles) than for resuspended material (precipitation from interstitial waters on surficial sediments). Close to the Mid-Atlantic Ridge, the bottom suspended matter exhibits higher Fe p/Al p andMn p/Al p ratios than in abyssal plains. A ridge crest source must be invoked to explain the striking enrichment of Mn p. This source could also explain the enrichment of Fe p, although primarily because the resuspended flux is small in that region, one cannot exclude the contribution of particles from the mid-water column.

Chemical tracers for particle transport in the Chesapeake Bay

Particulate material from the Susquehanna River is enriched in Fe (5–7%),allowing it to be distinguished from other sources of particles in surface waters of the Chesapeake Bay. Although the turbidity maximum removes most of the river-borne detritus, chemical composition of particles (SPM) indicates that Susquehanna River materials dominate the inorganic suspended matter in surface waters of the Bay at least 20–40 km further. Fe concentrations, Fe/Ti, and Fe/Zn ratios in surface water SPM still farther down the Bay indicate that those particles are a mixture of river derived and biological material and that shore erosion is not normally a source of surface water suspended sediments as far as the mouth of the Potomac. Seasonal variations 1 of elemental ratios such as Fe/Zn can also be used to demonstrate scavenging of soluble trace elements by particles during summer conditions.

Use of an oxidative destruction and quadrupole mass spectrometric (QMS) detection for the determination of the organic elemental composition of suspended matter in surface water

A study was made of the applicability of a system consisting of a combustion followed by QMS-detection for the determination of the elemental composition of organic matter suspended in surface water. The solid material obtained from several types of water was collected by centrifugation. The results show possible applications e.g. in the field of water characterization. A complete elemental analysis including pretreatment takes about 30 min.

Surface suspended matter off western Africa: relations of organic matter, skeletal debris and detrital minerals*

ABSTRACTComponents of suspended matter in surface waters between western Africa and the Mid‐Atlantic Ridge were removed by filtration and measured by scanning electron and optical microscopy. Skeletal debris from diatoms, dinoflagellates, and other plankton are most concentrated in Antarctic surface water and in regions of coastal upwelling. Detrital mineral grains are most concentrated in nearshore regions, from discharge of major rivers, erosion of sea cliffs, and deposition from offshore winds. Farther offshore are high concentrations of mineral grains brought by trade winds from deserts in both northern and southern Africa. The winds also bring freshwater diatoms and woody tissue. The remaining component on the filters is marine organic matter, mostly in thin films. These films trap skeletal debris and mineral grains. Presumably, animals that graze upon the films further concentrate the grains into faecal pellets whose rapid settling carries the grains into deeper waters and to the bottom. The films were found in all other areas of the world ocean from which surface samples were spot‐checked: off eastern Asia, off eastern North America, and the central Pacific. Thus they appear to be a major factor in marine sedimentation. In areas of upwelling off western Africa, the total suspended matter in surface waters averages about 0.1 mg/1 of filtrate, about five times that present in the open ocean. It consists of about 70% organic matter, 29.6% skeletal debris, and 0.4% mineral grains, in contrast with concentrations in the open ocean of 90%, 8% and 2%, respectively.

Size distribution of detrital mineral grains suspended in surface waters of the Yellow Sea and East China sea

Anisotropic detrital mineral grains were segregated microscopically from the suspended matter in surface waters of the Yellow Sea and East China Sea. Microscopic grain-size measurements of the anisotropic minerals were carried out for more than 80 slide specimens which are distributed homogeneously in the Yellow Sea and East China Sea. The distribution maps of mean grain size and sorting coefficients indicate that the mean size becomes coarser as one goes offshore, and the sorting coefficients are larger in the southern portion and smaller in the northern portion of this region. The clay-sized minerals in the suspended sediments carried out by the deltaic rivers of the continent were deposited in the nearshore area while coarser silt-sized minerals were suspended in offshore waters. The larger sorting coefficients (standard deviations) in the southern portion may imply that the silt-sized grains of offshore waters contain coarser sand-sized grains. The sand-sized grains may be supplied from offshore Taiwan and the Bashi Channel and transported by the main flow of the Kuroshio current.

Suspended matter in surface waters: influence of river discharge and of upwelling*

ABSTRACTAbout 4100 samples of suspended matter were collected by filtration of surface ocean waters in three large regions on the western sides of oceans and two on the eastern sides. Comparison of results shows that the non‐combustible fraction (chiefly detrital clays and silts with some siliceous and calcareous skeletal debris) generally dominates along the western sides of oceans, where large contributions of solid detrital sediment are made by rivers that drain much of the adjacent continents. The combustible fraction also is important off these rivers, but it is more important (both relative to the non‐combustible fraction and in absolute terms) along the eastern sides of oceans, where upwelling is intense.

Humates and other natural organic substances in the aquatic environment

The bulk of the organic matter in surface waters is derived from natural sources, not from man-made byproducts.

Particulate and soluble 210Pb activities in the deep sea

Particulate and soluble, 210Pb activities have been measured by filtration of large-volume water samples at two stations in the South Atlantic. Particulate phase 210Pb (caught by a 0.4-μm filter) varies from 0.3% of total 210Pb in equatorial surface water to 15% in the bottom water. The “absolute activity” of 210Pb per unit mass of particulate matter is about 10 7 times the activity of soluble 210Pb per unit mass of water, but because the mass ratio of particulate matter to water is about 10 −8, the particulate phase carries only about 10% of the total activity. In Antarctic surface water the particulate phase carries 40% of the total 210Pb activity; the absolute activity of this material is about the same as in other water masses and the higher fraction is due to the much larger concentration of suspended matter in surface water in this region. In the equatorial Atlantic the particulate phase 210Pb activity increases with depth, by a factor of 40 from surface to bottom, and by a factor of 4 from the Antarctic Intermediate Water core to the Antarctic Bottom Water. This increase with depth is predicted by our previously proposed particulate scavenging model which indicated a scavenging residence time of 50 years for 210Pb in the deep sea. A scavenging experiment showed that red clay sediment removes all the 210Pb from seawater in less than a week. The Antarctic particulate profile shows little or no evidence of scavenging in this region, which may be due to the siliceous nature of the particulate phase in circumpolar waters. Our previous observation that the 210Pb/ 226Ra activity ratio is of the order of 0.5 in the deep water is further confirmed by the two South Atlantic profiles analyzed in the present work.

Sources of Suspended Matter in Waters of the Middle Atlantic Bight

ABSTRACT Suspended matter collected in the Middle Atlantic Bight (the coastal segment of the United States between Cape Cod and Cape Hatteras) in September 1969 was predominantly organic: an average of 80% combustible organic matter in surface waters and 40)% near bottom. Total suspended concentrations decreased between the inner shelf and the shelf break by an order of magnitude in both near-surface and near-bottom waters. The noncombustible (ash) fraction of the suspended matter decreased over the same distance by one order of magnitude in the near-bottom waters and two orders of magnitude in surface waters. Recently contributed river sediment is not a significant constituent of the suspended matter in the waters of the shelf, particularly the outer shelf. Most of the inorganic material in suspension represents resuspended bottom sediments (at least some of which are relict) whose suspended concentrations are increased noticeably by storms.

Non‐combustible suspended matter in surface waters off eastern Asia*

ABSTRACTA total of about 1100 well‐distributed samples of suspended matter in surface waters off the length of eastern Asia are available. From these samples, 180 were selected for detailed examination of the non‐combustible fraction using optical and electron microscopy along with computer methods of particle measurement and counting. The results showed that, generally, all major components of the suspended matter are most abundant in the nearshore belt (combustible fraction, mineral grains of silt size, skeletal debris, and clay minerals), the result of mechanical transport of detrital sediment and chemical transport of nutrients from the land. Mineral grains of silt size average about 2%, skeletal debris plus clay minerals—23%, and combustible organic matter—75% of total sample weights, but the last two categories vary over a wide range depending upon geographical positions of the samples. Most evident is an oceanward decrease in percentage and concentration of the total noncombustible fraction and an oceanward increase in median diameter of the mineral grains.

Suspended Matter and Other Properties of Surface Waters of the Northeastern Atlantic Ocean

ABSTRACT Samples of suspended matter in surface waters were collected at 1534 stations off the west coast of Africa during two geophysical cruises of 1972 and 1973. Many positive correlations exist with respect to auxiliary measurements of winds, temperature, salinity, currents, chlorophyll, phytoplankton, zooplankton-nekton, dustfall, and proximity to major river mouths. Some of the relationships can be expressed in terms of oceanic zones. The most concentrated suspended matter (total, organic, and inorganic) occurs above the continental shelf north of Latitude 7°N, where the high concentration of organic matter is due to coastal upwelling (indicated by relatively low temperatures and salinities, and high chlorophyll and phytoplankton concentrations). The high concentration of inorganic m tter also present along the coasts is due to contributions by major rivers and heavy dustfall. Secondary concentrations of organic matter and the presence of related parameters typify open-ocean belts of divergence at the equator and south of the Sub-Tropical Convergence (south of Lat. 35°S).

Suspended matter in surface waters of the eastern Gulf of Guinea

Suspended matter in the surface waters of the eastern Gulf of Guinea was studied in relation to the prevailing oceanic currents and the sediment composition and source. A confused current system arises from the confluence of the Guinea Current and the South Equatorial Current in this area. Sediment-laden water is transported to the south of Fernando Póo into the Gulf in a south-westerly direction. The southeasterly flowing Guinea Current along the western edge of the Niger delta and the enormous sediment loads of the distributaries in this area contribute to a major lobe of suspended matter off the southwestern nose of the delta. Sediment concentration is inversely related to salinity in the northeastern Gulf. Sediment is also swept northwestward from the continental shelf of Gabon and the Congo Republic into the Gulf. Diatoms are the most abundant constituents with lesser amounts of organic aggregates and two varieties of fecal pellets.

Physical Properties and Suspended Matter of Surface Waters in the Southeastern Atlantic Ocean

ABSTRACT Samples of suspended matter in surface waters were obtained at about 750 stations in the southeastern Atlantic Ocean during a 5.5-month geophysical cruise of R/V ATLANTIS II. Concentrations were found to be related to patterns of upwelling as outlined by observations of wind direction and speed, surface water temperature, salinity, and color, seabird distribution and abundance, and the surface current pattern. The suspended matter is chiefly organic in origin owing to the high productivity of upwelled water on the continental shelf and south of the Subtropical Convergence.

Suspended matter in surface waters of the Atlantic continental margin from Cape Cod to the Florida Keys.

Appreciable Amounts Of suspended matter (> 1.0 milligram per liter) in surface waters are restricted to within a few kilometers of the Atlantic coast. Particles that escape estuaries or are discharged by rivers into the shelf region tend to travel longshoreward rather than seaward. Suspended matter farther offshore, chiefly amorphous organic particles, totals 0.1 milligram per liter or less. Soot, fly ash, processed cellulose, and other pollutants are widespread.

Size Distributions of Mineral Grains Suspended in Chesapeake Bay and Nearby Coastal Waters

Recognizable mineral grains constituted 2 to 15% of the suspended matter in surface waters collected in June 1965 from Chesapeake Bay and from the offshore area between Cape Henry and Cape Hatteras. In the upper bay, the mineral grain size became progressively finer in the down-bay direction. Mineral size distributions in the middle and lower bay showed little relation to those in either the upper bay or the offshore waters. Most of the mineral grains suspended in the offshore waters (considered on a weight basis) seemed to be derived from sources other than the bay effluent.