The direct determination in drinking water of perylene, chrysene, pyrene, benzo[a]pyrene, and benzo[k]fluoranthene, by front-face synchronous fluorimetry on a commercial SPE disk, has been evaluated. Sorbent treatment, influence of humic substances, and pH effect are discussed. In pure water the detection limits were estimated to be in the range 0.03-0.01 microg L(-1). A working pH in the range...

Introduction: Humic substances (HSs) are very complex and heterogeneous organic matter with high molecular weight and various functional groups, which are produced from the chemical and biological degradation of plants and animal tissues. HS can cause: colour, odour and taste problems in drinking water, biological growth in distribution systems, increase in chlorine demand for disinfection, mem...

Mingquan Yan a*, , Gregory Korshin , Dongsheng Wang c 3 a Department of Environmental Engineering, Peking University, The Key Laboratory 4 of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China; 5 b Department of Civil and Environmental Engineering, University of Washington, Box 6 352700, Seattle,WA 98195-2700, United States 7 c State Key Laboratory of Environmental Aquati...

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...

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 ...

To evaluate which microorganisms might be responsible for microbial reduction of humic substances in sedimentary environments, humic-reducing bacteria were isolated from a variety of sediment types. These included lake sediments, pristine and contaminated wetland sediments, and marine sediments. In each of the sediment types, all of the humic reducers recovered with acetate as the electron dono...

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, the main component of soil organic matter, could form an integral part of green and sustainable solutions to the soil fertility problem. However, their global-scale application is hindered from both scientific and regulatory perspectives by the lack of understanding of the molecular make-up of these chromatographically inseparable mixtures containing thousands of molecules. He...

In this study, the effects were investigated of salinity, foliar and soil applications of humic substances on the growth and mineral nutrients uptake of Corn (Hagein, Fardy10), and the comparison was carried out of the soil and foliar applications of humic acid treatments at different NaCl levels. Soil organic contents are one of the most important parts that they directly affect the soil ferti...

Two aquatic fulvic acids and one soil humic acid were irradiated to examine the resulting changes in the redox and photochemical properties of the humic substances (HS), the relationship between these changes, and their relationship to changes in the optical properties. For all HS, irradiation caused photooxidation, as shown by decreasing electron donating capacities. Photooxidation was accompa...