humic substances
154
active properties. They are complex, brown, mixed compounds with melanoid structure, and contribute to so-called Gelbstoff. Part of the marine humic
acids may be produced in situ, but in coastal regions they are predominantly
of terrestrial origin.
humic substances major organic constituents of soils and sediments. In seawater
they partly determine, for instance, the solubility of substances, sorption,
and precipitation of numerous elements, and the optical properties of water.
They exhibit no specific physical and chemical characteristics (e.g., a sharp
melting point, or an exact elementary composition). Humic substances are
dark-colored, acidic, in seawater predominantly aliphatic, hydrophilic,
chemically heterogeneous and complex, structurally complicated, poly-electrolyte-like substances. Molecular weight from a few hundred to several
thousand. According to their behavior in aqueous solutions at certain pH
values they are divided into fulvic acids, humic acids and humic substances. The
genesis of humic substances and the related Gelbstoff occurs during the condensation of carbohydrates with amino acids. In seawater humic substances
probably also contain remnants of lipid biopolymers.
hummock pile of fractural sea ice, -7ice.
hydraulic piston corer -7corer.
hydrocarbons group of organic compounds containing only two elements, hydrogen and carbon. On the basis of their structure they are divided into aliphatics and aromatics, the former being subdivided into alkanes, alkenes, alkyns,
and their cyclic analogs. The simplest hydrocarbon is methane. In seawater
hydrocarbons occur in concentrations ranging from 1 to 50 fig dm- 3 ; in the
surface microlayer much higher concentrations have been observed. The content of superficial sediments is in the order of 1 to 100 fig g- l of dry sediment.
hydrocast oceanographic sampling by the lowering of a series of sampling bottles
into the water column and retrieval of water samples at an oceanographic station.
Hydrocorallina order of the class Hydrozoa (phylum Cnidaria). The ectoderm lays
down an exoskeleton consisting of calcareous grains. The colony has two types
of polyps: the gastrozooids with a mouth surrounded with tentacles which
nourish the colony, and the dactylozooids with capitate tentacles which
catch prey. There are also medusae with a very short free-living stage, formed
by budding. The forms included in this group are mostly associated with
reef corals in tropical seas.
hydrodynamics in hydrodynamics (or fluid dynamics) the effect of mechanical
forces on a moving fluid is investigated. In such studies the fluid is consid-
154
active properties. They are complex, brown, mixed compounds with melanoid structure, and contribute to so-called Gelbstoff. Part of the marine humic
acids may be produced in situ, but in coastal regions they are predominantly
of terrestrial origin.
humic substances major organic constituents of soils and sediments. In seawater
they partly determine, for instance, the solubility of substances, sorption,
and precipitation of numerous elements, and the optical properties of water.
They exhibit no specific physical and chemical characteristics (e.g., a sharp
melting point, or an exact elementary composition). Humic substances are
dark-colored, acidic, in seawater predominantly aliphatic, hydrophilic,
chemically heterogeneous and complex, structurally complicated, poly-electrolyte-like substances. Molecular weight from a few hundred to several
thousand. According to their behavior in aqueous solutions at certain pH
values they are divided into fulvic acids, humic acids and humic substances. The
genesis of humic substances and the related Gelbstoff occurs during the condensation of carbohydrates with amino acids. In seawater humic substances
probably also contain remnants of lipid biopolymers.
hummock pile of fractural sea ice, -7ice.
hydraulic piston corer -7corer.
hydrocarbons group of organic compounds containing only two elements, hydrogen and carbon. On the basis of their structure they are divided into aliphatics and aromatics, the former being subdivided into alkanes, alkenes, alkyns,
and their cyclic analogs. The simplest hydrocarbon is methane. In seawater
hydrocarbons occur in concentrations ranging from 1 to 50 fig dm- 3 ; in the
surface microlayer much higher concentrations have been observed. The content of superficial sediments is in the order of 1 to 100 fig g- l of dry sediment.
hydrocast oceanographic sampling by the lowering of a series of sampling bottles
into the water column and retrieval of water samples at an oceanographic station.
Hydrocorallina order of the class Hydrozoa (phylum Cnidaria). The ectoderm lays
down an exoskeleton consisting of calcareous grains. The colony has two types
of polyps: the gastrozooids with a mouth surrounded with tentacles which
nourish the colony, and the dactylozooids with capitate tentacles which
catch prey. There are also medusae with a very short free-living stage, formed
by budding. The forms included in this group are mostly associated with
reef corals in tropical seas.
hydrodynamics in hydrodynamics (or fluid dynamics) the effect of mechanical
forces on a moving fluid is investigated. In such studies the fluid is consid-