Humic substances are a heterogeneous class of moderate molecular weight, yellow-colored biomolecules present in all soils, sediments, and natural waters. Although humic substances are generally resistant to microbial degradation under anaerobic conditions, some microorganisms in soils and sediments can use quinone moieties in humic substances as electron acceptors. Laboratory experiments have s...

Humic substances, the dark-colored, natural organic polyelectrolytes that are found in practically all soils, sediments, and natural water, strongly interact with both inorganic and organic pollutants. Inorganic cationic species generally undergo complexation reactions with humic substances. The binding of cations, such as cupric ions, by humic substances often markedly reduces their toxicity t...

The humic substances including humic acid (HA) and fulvic acids (FAs) extracted from a refuse compost were investigated the average conditional concentration quotients of the complexes formed by the reaction of heavy metals with the humic substances. The characteristics of these humic substances were previously investigated by a related study. The concentrations of the free ions of Pb, Cu, Cd, ...

Organic matter from profundal lake sediments was fractionated and analyzed with high depth resolution, and the size-class distribution of humic substances was determined by gel-permeation chromatography. Together with a depthdependent increase of the thermal stability of the organic matter and an increasing C/N atomic ratio of the humic acids, the size-distribution patterns of di€erent fraction...

The Pseudomonas sp. PAMC 26793 was isolated because of its high ability to degrade humic acids from a subarctic grassland in Alaska. We sequenced the PAMC 26793 genome to discover the genes for degradation of natural humic substances and to provide further information for the degradation process of soil bacteria in a low-temperature environment.

Humic substances mainly humic acids constitute the major fraction of natural organic matter in water supplies. They play an important role in the formation of harmful disinfection by products. Degradation of humic acids by means of ultraviolet radiation and ultrasonic irradiation processes was investigated in a laboratory-scale batch photoreactor equipped with an 300 W immersed-type medium-pres...

The dissimilatory Fe(III) reducer Geobacter metallireducens reduced Fe(III) bound in humic substances, but the concentrations of Fe(III) in a wide range of highly purified humic substances were too low to account for a significant portion of the electron-accepting capacities of the humic substances. Furthermore, once reduced, the iron in humic substances could not transfer electrons to Fe(III) ...

High cation exchange capacity and organic matter content of crude humic substances from compost could be exploited to reduce ammonia loss from urea and to as well improve rice growth and soil chemical properties for efficient nutrients utilization in lowland rice cultivation. Close-dynamic air flow system was used to determine the effects of crude humic substances on ammonia volatilization. A p...

Humic substances, i.e. dark paramagnetic polymeric anionic polyelectrolytes, belong to the most widespread macromolecular substances of biogenic origin in soil and aquatic environments. The exact structure of humic substances is unknown because of their complexity resulting from unrecurring precursors, from their composition and their process of synthesis. Degradation processes of these substan...

Surface water and groundwater sources for human supply require treatment to remove substances that can cause human diseases and rejection. Aquatic humic substances, such as iron and manganese, interfere with the aesthetic and sanitary quality of the water because they cause color, odor and taste unpleasant. In addition, humic substances can form trihalomethanes which are serious harmful substan...