Humic Substances

Increasing evidences have indicated that humic substances can induce plant growth and productivity by functioning as an environmental source of auxinic activity. Here we comparatively evaluate the effects of indole-3-acetic acid (IAA) and humic acids (HA) isolated from two different soils (Inseptsol and Ultisol) and two different organic residues (vermicompost and sewage sludge) on root development and on activities of plasmalemma and tonoplast H+ pumps from maize roots. The data show that HA isolated from these different sources as well as low IAA concentrations (10−10 and 10−15 M) improve root growth through a markedly proliferation of lateral roots along with a differential activation not only of the plasmalemma but also of vacuolar H+-ATPases and H+-pyrophosphatase. Further, the vacuolar H+-ATPase had a peak of stimulation in a range from 10−8 to 10−10 M IAA, whereas the H+-pyrophosphatase was sensitive to a much broader range of IAA concentrations from 10−3 to 10−15 M. It is proposed a complementary view of the acid growth mechanism in which a concerted activation of the plasmalemma and tonoplast H+ pumps plays a key role in the root cell expansion process driven by environment-derived molecules endowed with auxinic activity, such as that of humic substances.

Carotenoids are a group of phytochemicals that are recognized as playing an important role in the prevention of several degenerative diseases due to their antioxidant activity. The low water-solubility and poor photostability of β-carotene, a potentially important dietary antioxidant, prompted us to investigate β-carotene complexes able to increase its water solubility as well as its photostability in aqueous solution. In this work we have used humic acid in order to synthesize β-carotene–humic acid complexes in different ratios.Complexes were characterized by FT-IR and DSC. β-Carotene determination were performed by HPLC and antioxidant activity of β-carotene, humic acid and the complexes were determined by the TEAC method. The formulation β-carotene–humic acid 2:1 showed the highest photostability and water solubility. The antioxidant activity of the complexes was about 20 times lower than “free” β-carotene, suggesting a decreased chemical reactivity of the carotenoid in the complex. We showed that complexation of β-carotene with humic acids was able to increase its water solubility and photostability, and to affect the antioxidant activity of β-carotene after inclusion in HAs. This work provides a useful tool to avoid antioxidants photodegradation and oxidation by radicals, thus maintaining their biological activity.

A new sample pre-treatment technique termed cone-shaped membrane liquid phase microextraction (CSM-LPME) was developed and combined with micro-liquid chromatography (micro-LC) for the determination of selected pesticides in water samples. Four pesticides (hexaconazole, procymidone, quinalphos and vinclozolin) were considered as target analytes. Several important extraction parameters such as types of extraction solvent, agitation rate, pH value, total exposure time and effect of salt and humic acids were optimized. Enrichment factors of >50 folds were easily achieved within 20 min of extraction. The analytical data demonstrated relative standard deviations for the reproducibility of the optimized CSM-LPME method ranging from 6.3 to 7.5%. The correlation coefficients of the calibration curves were at least 0.9995 across a concentration range of 2–100 μg/L. The detection limits for all the analytes were found to be in the range of 1.1–1.9 μg/L.

Tbe potential for using coal-derived humic substances to improve the available water holding capacity (AWC) and awegate stability of typical Mediterranean soils was evaluated in the laboratory using an agricultural surface (0-20 cm) soil from each of three regions of Ital}, (Sicil}, Tuscany and Venetia) and five rates of humic acids (HA), 0, 0.05, 0.10, 0.50 and 1.00 g/kg.There were significant (P < 0.05) differences between the field capacity (FC), permanent wilting point (PWP), and availablewatercapacity(AWC) values of the controls and those treated with 0.05 glkg of the HA. Beyond this rate, differences in these pr[)perties were not significant. At the 1.00 g/kg HA rate, the relati,'e improvements in AWe over the three controls were 30%, 10% and 26%. Low rates (0.05 to 0.10 g/kg) of HA were also needed to obtain a 40 to 120% improvement in aggregate stability of these soils relative to the controls. These results indicate that the addition of highly humified organic matter such as coal-derived humic substances can improve the structural and water retention properties of degraded arable soils. However, since there is not yet any direct evidence that these humic materials can ameliorate soils under field conditions, field studies will be needed to validate these results.

Hot springs are the important natural sources of geothermally heated groundwater from the Earth's crust. Kuan-Tzu-Ling (KTL), Chung-Lun (CL) and Bao-Lai (BL) are well-known hot springs in southern Taiwan. Fluid and mud (sediments) samples were collected from the eruption points of three hot springs for detailed biogeochemical characterization. The fluid sample displays relatively high concentrations of Na+ and Cl− compared with K+, Mg2+, Ca2+, NO2 −, and SO4 2−, suggesting a possible marine origin. The concentrations of Fe, Cr, Mn, Ni, V and Zn were significantly higher in the mud sediments compared with fluids, whereas high concentrations of As, Ba, Cu, Se, Sr and Rb were observed in the fluids. This suggests that electronegative elements were released during sediment-water interactions. High As concentration in the fluids was observed to be associated with low redox (Eh) conditions. The FTIR spectra of the humic acid fractions of the sediments showed the presence of possible functional groups of secondary amines, ureas, urethanesm (amide), and silicon. The sulfate-reducing deltaproteobacterium 99% similar to Desulfovibrio psychrotolerans (GU329907) were rich in the CL hot spring while mesophilic, proteolytic, thiosulfate- and sulfur-reducing bacterium that 99% similar to Clostridium sulfidigenes (GU329908) were rich in the BL hot spring.

The photocatalytic bleaching of dyes using TiO2 has appeared promising in laboratory studies, but little attention has been focused on whether other species such as might be found in wastewater have a deleterious effect on the photobleaching. This study describes the effects that result from the presence of ionic species, organic solvents and humic substances on the photobleaching of several dyes. The manner in which the photobleaching was affected by the presence of adventitious materials was carefully examined with an eye toward elucidating the mechanistic origin of the loss of the photochemical efficiency in the reaction. The overall retardation effects can be attributed to the combination of light attenuation, inhibition and competition effects.

Shilajit has been used as a rejuvenator for ages in Indian ancient traditional medicine and has been validated for a number of pharmacological activities. The effect of processed shilajit which was standardized to dibenzo-α-pyrones (DBPs;0.43% w/w), DBP-chromoproteins (DCPs; 20.45% w/w) and fulvic acids (56.75% w/w) was evaluated in a rat model of chronic fatigue syndrome (CFS). The mitochondrial bioenergetics and the activity of hypothalamus-pituitary-adrenal (HPA) axis were evaluated for the plausible mechanism of action of shilajit. CFS was induced by forcing the rats to swim for 15mins for 21 consecutive days. The rats were treated with shilajit (25, 50 and 100mg/kg) for 21 days before exposure to stress procedure. The behavioral consequence of CFS was measured in terms of immobility and the climbing period. The post-CFS anxiety level was assessed by elevated plus maze (EPM) test. Plasma corticosterone and adrenal gland weight were estimated as indices of HPA axis activity. Anal...

Humic Substances (HS) occur naturally in our environment and are the remains of a process called humification, which is the biodegradation of biomass that then recombines and converts into dark colored complex compounds with no definite chemical structure. These are the end result of microbial degradation but resistant to further microbial degradation. It has a strong global presence as a dietary supplement and cosmetics applications for different beneficial uses. Till date its exploration as a pharmaceutical excipient has been limited to academic research only but the data being presented augurs a good commercial success.

The scientific understanding of the molecular size and shape of humic
substances (HS) is critically reviewed. The traditional view that HS are
polymers in soil is not substantiated by any direct evidence but is assumed
only on the basis of laboratory experiments with model molecules
and unwarranted results produced by incorrectly applying either analytical
procedures or mathematical treatments developed for purified and
undisputed biopolymers. A large body of evidence shows an alternative
understanding of the conformational nature of HS, which should be regarded
as supramolecular associations of self-assembling heterogeneous
and relatively small molecules deriving from the degradation and decomposition
of dead biological material. A major aspect of the humic
supramolecular conformation is that it is stabilized predominantly by
weak dispersive forces instead of covalent linkages. Hydrophobic (van
der Waals,
-
, CH-
) and hydrogen bonds are responsible for the apparent
large molecular size of HS, the former becoming more important
with the increase of pH. This innovative understanding of the nature of
HS implies a further development of the science and technology for the
control of the chemistry and reactivity of natural organic matter in the
soil and the environment. (Soil Science 2001; 166:810–832)

Increased use of humic substances in agriculture has generated intense interest among producers, consumers, and regulators for an accurate and reliable method to quantify humic acid (HA) and fulvic acid (FA) in raw ores and products. Here we present a thoroughly validated method, the new standardized method for determination of HA and FA contents in raw humate ores and in solid and liquid products produced from them. The methods used for preparation of HA and FA were adapted according to the guidelines of the International Humic Substances Society involving alkaline extraction followed by acidification to separate HA from the fulvic fraction. This is followed by separation of FA from the fulvic fraction by adsorption on a nonionic macroporous acrylic ester resin at acid pH. It differs from previous methods in that it determines HA and FA concentrations gravimetrically on an ash-free basis. Critical steps in the method, e.g., initial test portion mass, test portion to extract volume ...

The health implications of waste scavenging in solid waste management in Tema metropolis, Ghana, has been a cause of concern as no proper attention has been given to the scavengers. To isolate, characterize and identify pathogens associated with municipal waste that may be of public health importance; samples were collected from three dumpsites in Tema, Ghana. Serial dilutions of the samples were carried out and aliquots (1 ml) of the diluted samples were inoculated onto appropriate media. Similarly, hands of waste scavengers were swabbed prior and during scavenging, as well as PCA and PDA plates exposed at the dumpsites for microbial analysis. Biochemical test was carried out to identify the particular types of bacteria isolated. The study revealed eleven genera of bacteria and four genera of fungi. It was inferred from this study that microbial load at waste dumpsites poses a great threat not only to waste scavengers but also to the society as well, as scavengers serve as routes for the transmission of certain pathogens associated with waste to the larger society, thereby, constituting some public health hazards. The paper recommended that proper personal protection of the scavengers and integrating this informal sector into waste management planning, building on their practices and experiences while working to improve efficiency, living and working conditions of the scavengers should be encouraged.

Landfill leachate consists mostly of a high content of refractory organic matter, ammonia and toxic compounds. All of these compounds, regardless of their nature, have a potential pollution effect on local ground and surface waters. In this context, the purpose of the present study was to evaluate a treatment process (coagulation-flocculation with lime coupled with nanofiltration) applied to landfill leachate from Seropédica, Rio de Janeiro (Brazil). Jar tests were conducted to determine the optimum dosage of lime (ranged from 0 to 10 g L-1) and, at optimum lime dose, ammonia nitrogen was removed during coagulation-flocculation process due to high pH. The process was settled for 6 h with slow stirring (50 rpm) to promote air entrainment and NH3-N stripping before using the final treatment step of nanofiltration at 8 bar. After ammonia stripping, NH3-N was reduced from 1236 mg.L-1 to 353 mg.L-1 (71% removal efficiency). At the end of the combined treatment, TOC (Total Organic Carbon), HS (Humic Substances) and COD (Chemical Oxygen Demand) removals were 89%, 80% and 94%, respectively. The results showed that the combined process was effective in the removal of recalcitrant compounds and NH3-N.