To study the effect of nitrogen fertilizer sources and foliar spray of organic acids on rice crop, In this regard, this test was performed in 2010 and 2011 years at ElGemmeiza Agricultural Research Station, El-Gharbia Governorate located at lat. 30.47, long 31.00 and 14.80 m above the mean sea; the used design was split plot randomized complete block with 3replications. Main plots, two nitrogen...

Plug-flow biofilm reactors colonized by microorganisms in streamwater were used to measure the concentration and composition of biodegradable dissolved organic C (BDOC) in White Clay Creek. During the 4-month study period, DOC ranged from 0.8 to 10.4 mg C liter-’ and was, on average, composed of 75% humic substances, 13% carbohydrates, 2% amino acids, and 18% > 100 kDa. The carbohydrates were p...

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...

The present study examines the role of humic acid, as a representative of dissolved organic matter, in Cd(II), Cu(II), and Pb(II) speciation and biouptake by green microalgae. Cellular and intracellular metal fractions were compared in the presence of citric and humic acids. The results demonstrated that Cd and Cu uptake in the presence of 10 mg L(-1) humic acid was consistent with that predict...

A major concern of the chlorination of aquatic humic materials is the ubiquitous production of trihalomethanes. A large number of other chlorinated organic compounds, however, have been shown to be formed by chlorine's reaction with humic substances. In this study, humic material was concentrated from a coastal North Carolina lake and chlorinated at a chlorine to carbon mole ratio of 1.5 at pH ...

Humic acids extracted from different soils. The stability constants of metal humates and acid dissociation constant humic acids were calculated. Forms of metals in natural waters was determined with use account their chemical composition and content and properties of organic matter. We assessed metals speciation in water objects with account for competitive reactions resulting in formation of h...

The solution and CPMAS spectra of humic acids extracted from the composted municipal refuse of three Spanish cities (Sevilla, Granada and Puerto Real) have been obtained at 75.4 MHz. The spectra are discussed qualitatively and the signals assigned to the various chemical struc­ tures forming the humic acids. It is attempted to learn the limits for the quantitative determination of signal areas ...

Humic acids are amphiphilic species whose behavior in aqueous solution suggests that they form pseudomicellesÐaggregates akin to the micelles familiar from synthetic surfactant chemistry. It is thought that humic pseudomicelles can be formed by both intramolecular coiling and intermolecular association, depending on the molecular weight, structural characteristics, and polydispersity of the hum...

We report development of a novel parameter for quantifying the amount of humic and fulvic acids per unit surface area in a particular soil. This quantity, the "humic coverage index" (HCI), provides a measurement of the relative spatial extents and/or thicknesses of the humic/fulvic overlayers in different soils, and, therefore, can be used in modeling various soils' behavior in sequestration pr...