Fulvic, humic, acetic, N-bulyric, formic, lactic, and propionic acids were inhibitory to the survival or reproduction of Aphelenchus avenae, Aphelenchoides goodeyi, Helicotylenchus pseudorobustus, Meloidogyne hapla or Xiphinema americanum. Reproduction of H. pseudorobustus and M. hapla significantly increased with increasing amounts of muck added to sand, and with the initial amount of nematode...

Brown humic acids (BHAs) constitute the most polar and soluble fraction of humic acids. Their colloidal character and their high number of functional surface groups justify their higher reactivity as against metallic cations with respect to other humic fractions (i.e., gray humic acids and humins). The aim of this work is to study the retention mechanisms of Cu(II), Ni(II), and Co(II) on a BHA ...

Models for humic and fulvic acids are discussed based on 13 C liquid state NMR spectra combined with results from elemental analysis and titration studies. The analysis of NMR spectra is based on a full reconstruction of the NMR spectrum done with help of 13 C-NMR data bases by adding up chemical shifts of all substructures from the proposed models. A full reconstruction makes sure that all car...

The goal of these studies was to determine how sorption by humic acids affected the bioavailability of polynuclear aromatic hydrocarbons (PAHs) to PAH-degrading microbes. Micellar solutions of humic acid were used as sorbents, and phenanthrene was used as a model PAH. Enrichments from PAH-contaminated soils established with nonsorbed phenanthrene yielded a total of 25 different isolates represe...

Experiments in batch equilibrium system were carried out to evaluate the importance of physical and chemical factors determining the sorption efficiency of humic substances (HS) on aquifer material, which has been used for artificial recharge of groundwater (ARG) in drinking water production. Results showed that an increase of the amount of clay in the aquifer material and a decrease of pH in w...

Over at least twelve years of actual field experience with an ample variety of humic acid formulations (some of them developed many years before) have given us a singular degree of expertise in Latin America and a few other markets. Among other things, we have learned to distinguish between humic acids of high biological value, and humic substances of little biological activity. We have found c...

The interaction of sulfonamide antimicrobial agents with smectite clay minerals and humic acid (HA)-clay complexes was investigated in batch experiments to assess the influence of adsorbed humic acid on sulfonamide sorption. Soil HA-clay complexes were produced at HA:clay ratios of 1:5, 1:50, and 1:100 (w/w). Vibrational and electronic spectroscopy indicated the preferential adsorption of polar...

Humic substances are generally seen as important soil and natural water components. They are formed during humification of organic matter by soil microorganisms. Humic substances are a mixture of complex organic compounds that are usually separated into three fractions: humic acids, fulvic acids and humins. The properties of humate products on the market depend on the ratios between these fract...