Residue bound

The term bound residue was adopted by the International Union of Pure and Applied Chemistry (lUPAC) in 1984. According to this definition and that of the European Commission (adopted in 1991), nonextractable residues in soil are 

The environmental significance of bound residues must be considered in relation to natural organic matter (Barraclough et al. 2005). Contaminants entering the subsurface contain many functional groups similar to those of natural organic matter 

Structural type Bound residues (% of applied) Parent detected 

The mechanism of bound residue formation is better understood today due to the use of advanced extraction, analytic, and mainly spectroscopic techniques (e.g., electron spin resonance, ESR nuclear magnetic resonance, NMR Fourier transform infrared spectroscopy), methods that are applied without changing the chemical nature of the residues. 

To calculate the release through diffusion of an entrapped residue, Barraclough et al. (2005) considered the size of organic matter particles (effective radius 10 to 10 cm) and the effective diffusion coefficient of small organic molecules in a sorbing medium (D 10 cm s )- The time for 50% of the material in a sphere to diffuse out is given by 

4-Dichloroaniline is reported to bind to lignin [10], while pentachlorophenol binds principally to hemicellulose in cell cultures but is associated with a diverse range of macromolecules, including hemicellulose, protein and lignin, in whole plants [11]. 

The chemicals were formulated to facilitate effective application in aqueous media then sprayed onto established wheat plants grown in large containers of soil in a glasshouse. The application timing for each chemical was optimized for appropriate macromolecule biosynthesis in the crop, hence (XVI) was applied only 

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El Zorgani GA, Omer IS, Abdullah AM. 1986. Bound residues of endosulfan and carbofuran in soil and plant material. Proceedings of the Final Research Co-ordination Meeting on Isotopic Tracer-aided Studies of Unextractable or Bound Pesticide Residues in Soil, Plants, and Food. Vienna, Austria International Atomic Energy Agency, 51-56. 

Dec J, K Haider, A Benesi, V Rangaswamy, A Schaffer, E Eernandes, J-M Bollag (1997a) Formation of soil-bound residues of cyprodinil and their plant uptake. J Agric Eood Chem 45 514-520. 

Extraction of residues from soil samples is much more difficult than their extraction from plant or water samples. The pesticide residues in the soil exist often in several forms as bound residue , which may affect the extraction efficiency of pesticides from the soil. Then, various extraction methods such as organic solvent extraction, Soxhlet extraction, sonication extraction, microwave dissolution and supercritical fluid extraction (SEE) are used. Some extraction methods are described in the following. 

Dinitroaniline herbicides have low soil mobility potential. Herbicide residues in the treated field are usually incorporated into the upper layers of the soil mainly as unextractable bound residue therefore, the movement of dinitroaniline herbicides from soil to the water compartment is minimal. Run-off is the principal route, which could lead to the contamination of surface waters. Residue methods were developed to measure the parent concentration in water samples. 

Some agrochemicals bind strongly to the soil component as bound residues, which cannot be extracted without vigorous extraction procedures. In this case, an acidic (e.g., hydrochloric acid, sulfuric acid) or alkaline solution (e.g., sodium hydroxide, potassium hydroxide) can be used as an extraction solvent, and also heating may be effective in improving the extraction of the residues. Analytical procedures after the extraction are the same as above, but a filtration procedure may be troublesome in some of these situations. However, these procedures are rare exceptions or are needed for specific chemicals that are stable under such harsh extraction conditions. 

It is likely that cross-linking of an organic copolymer proceeds through a stage of excitation and photochemical conversion of photosensitive side-chain organotin fragments containing coordination-bound residues. 

Schiavon, M. 1988b. Studies of the movement and the formation of bound residues of atrazine, of 14 of its chlorinated derivatives, and of hydroxyatrazine in soil using 14C ring-labeled compounds under outdoor conditions. Ecotoxicol. Environ. Safety 15 55-61. 

Dec J, Haider K, Benesi A, Rangaswamy V, Schaffer A, Pliicken U, Bollag J-M. Analysis of soil-bound residue of l3C-labeled fungicide cyprodinil by NMR spectroscopy. Environ. Sci. Technol. 1997 31 1128-1135. 

The chelate effect in proteins is also important, since the three-dimensional (3-D) structure of the protein can impose particular coordination geometry on the metal ion. This determines the ligands available for coordination, their stereochemistry and the local environment, through local hydrophobicity/hydrophilicity, hydrogen bonding by nearby residues with bound and non-bound residues in the metal ion s coordination sphere, etc. A good example is illustrated by the Zn2+-binding site of Cu/Zn superoxide dismutase, which has an affinity for Zn2+, such that the non-metallated protein can extract Zn2+ from solution into the site and can displace Cu2+ from the Zn2+ site when the di-Cu2+ protein is treated with excess Zn2+. 

FIGURE 5.6 Reaction of ninhydrin (trioxohydrindene hydrate) with the amino group of a bound residue (A) generates the Schiff s base. Hydrolysis after shift of the double bond generates the aldehyde and another amine which reacts (B) with a second molecule of ninhydrin to give an equilibrium mixture of the anion depicted and its tetraoxo form with a maximum of absorbance at 570 nm. 

The humic/organic matter coatings of different solid phases (i. e., SPm /SP0M), such as soils, sediments, suspended solids, colloids, and biocolloids/biosolids, interact with organic pollutants in aqueous systems in various ways. Adsorption is an important interaction mode. The reversibility and/or irreversibility of the adsorption processes is of major importance. The question whether the bound residues of pollutants are to be considered definitely inactivated has been the focus of extensive research. This question was posed as follows. Have the adsorbed pollutants become common components incorporated into the humic polymer coating of solid phases (i. e., being absorbed), or are they only momentarily inactivated in reversibly bound forms thus representing a possible source of pollution by a time-delayed release of toxic units ... 

Chemisorption involving covalent bonds as well as bound residue formation is also excluded, which is defined as any organic carbon remaining after exhaustive extraction that results from degradation of parent molecules. 

When DOC-bound residues are extracted along with the dissolved phase (i.e., the total concentrations are measured), then the ratio of the truly dissolved concentrations (Cw) to the total concentration (Q) of an HOC can be estimated by... 

Soil. Hydrolyzes in soil forming ethyl mercaptan, carbon dioxide, and dialkylamine (half-life approximately 2-5 wk) (Hartley and Kidd, 1987). At recommended rates of application, the half-life of molinate in moist loam soils at 21-27 °C was approximately 3 wk (Humburg et al., 1989). Rajagopal et al. (1984) reported that under flooded conditions, molinate was hydroxylated at the 3- and 4-position with subsequent oxidation forming many compounds including molinate sulfoxide, carboxymethyl molinate, hexahydroazepine-l-carbothioate, 4-hydroxymolinate, 4-hy-droxymolinate sulfoxide, hexahydroazepine, 5-methyl hexahydroazepine-l-carbothioate, 4-keto-molinate, 4-hydroxyhexahydroazepine, 4-hydroxy-Wacetyl-hexahydroazepine, carbon dioxide, and bound residues. 

Khan, S.U. Distribution and characteristics of bound residues of promettyn in an organic soil, J. Agric. Food Chem., 30(1) 175-179, 1982. 

Lichtenstein, E.P. Bound residues in soils and transfer of soil residues in crops. Residue Rev., 76 147-153.1980. 

Adsorption removes a compound from the bulk phase and thus affects its behavior in the subsurface environment. Due to some hysteresis effects, sometimes reflected in formation of bound residues, the release of compounds from the solid phase to the liquid or gaseous phase does not always reach the amount of adsorbate retained on solid surfaces. 

Chapter 5 discusses contaminant adsorption on geosorbents and includes a short description of the surface properties of adsorbents and the methodology for quantifying adsorption. The chapter continues with a presentation of adsorption of various types of toxic chemicals on the subsurface solid phase. In addition to physicochemical adsorption, contaminants can be retained in the subsurface by precipitation, deposition, and trapping. These topics, as well as hysteresis phenomena and formation of bound residues, are discussed. 

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