An understanding of the chemistry and reactions of humic acids and related substances is crucial to an understanding of the nature and properties of soils. A comprehensible structural representation of humic substances is presented and the simplified model is used to illustrate: (i) the way in which stable humus is formed from lignin; (ii) forms of organic N in soils; (iii) the interaction of h...

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, ...

Mobile and potentially mobile forms of heavy metals are probably one of the most important toxic hazards in the environment. Besides pH, which is a factor influencing the mobility/availability of heavy metals to the greatest extent, the content and mainly the quality of soil organic matter play a very important role in the evaluation of heavy metal behaviour in the environment. The fraction of ...

A strain of Pewicillizi?tz freqzientans was successfully employed for partial degradation and characterization of humic acids. Salicyl alcohol and salicylalclehyde were detected i n culture filtrates of the fungus ~rtilizing humates under reduced oxygen tension. The enzyme systems iiivolved in the degradation of humic acids were adaptive. The humate-adapted lnyceliirln was capable of metabolizi...

In the current research, the effects of some organic fertilizers as fulvic and humic acids on the vegetative growth of pistachio seedlings in a semi-hydroponic culture containing Fe-EDDHA (as a synthetic fertilizer) and FeSO4 (as an inorganic fertilizer) were investigated. The alkalinity is recognized as a main problem in pistachio orchards, therefore the pH of nutrient solution was ...

The time course photodegradation of the Nordic aquatic fulvic and humic acids and Suwannee River XAD-4 acids subjected to UV irradiation with an unfiltered medium pressure mercury lamp was studied by liquid-state 13C nuclear magnetic resonance. Photodecarboxylation was a significant pathway in all cases. Decreases in ketone, aromatic, and O-alkyl carbons were observed throughout the course of t...

Earthworms (Eisenia foetida) produce humic substances that can influence plant growth by mechanisms that are not yet clear. In this work, we investigated the effects of humic acids (HAs) isolated from cattle manure earthworm compost on the earliest stages of lateral root development and on the plasma membrane H(+)-ATPase activity. These HAs enhance the root growth of maize (Zea mays) seedlings ...

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...

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...