Physico-chemical aspects of the availability of pesticides in the soil. I.—Leaching of Pesticides from Granular Formulations

The way in which a pesticide is leached from a granular formulation differs from the way in which it is leached from a spray or dust formulation. This difference arises because granular applications do not provide the uniformity of coverage of the soil surface attainable with applications of finely divided sprays and dusts. This means that, besides the climatic factors such as temperature and quantity and intensity of rainfall that affect leaching, with granular formulations the distribution of granules over the soil is equally important. Thus the quantity of pesticide applied, the granule size, the pesticide content of the granules and their density may all affect the rate at which a pesticide is leached from the formulation. The inter-relation between these factors has been considered theoretically and the theoretical conclusions have been tested using granules prepared by agglomeration and containing the herbicide ‘Prefix’ (2,6-dichlorothiobenzamide). The effect of solubility of the pesticide in water has been studied using various pesticides having a range of water solubilities. As expected, the results show that the rate at which the pesticide is leached depends upon its solubility, but that the extent to which the granules break down under the influence of water can also be important.     

The aqueous extraction of glucosinolates from rapeseed

The losses of seed constituents from Brassica campestris var. Toria for various conditions of the leaching process developed at the Overseas Development Natural Resources Institute (ODNRI) were studied. Boiling seeds for 3 min at a seed/water ratio of 1:3 was sufficient to allow inactivation of the enzyme myrosinase; higher ratios did not increase losses in any of the constituents studied.
Heat treatment of the seeds (5 min in boiling water) reduced the nitrogen solubility at the native pH (6.5) from 28 to 8%. The pH had little effect on the extent of glucosinolate leaching from coarsely ground seeds and the minimum protein loss occurred close to the native pH. Increased water temperatures (40, 50 and 80°C) did not lead to an increased leaching efficiency over ambient temperature (20°C). Seed/water ratio was found to be the most important factor during leaching. Cross-current extraction over three stages at a seed/water ratio of 1:10 reduced the glucosinolate content by 98% while the crude protein loss was about 8.6%.     

Pea Starch Annealing: New Insights

Three different pea starches were annealed in excess water at 45 °C for 24 and 72 h, and the changes in their structure and functionality were determined. Annealing resulted in slightly irreversible swelling with leaching of some amylose molecules, which was accompanied by small changes in granular morphology and relative crystallinity, but significant changes in functionality such as decreased swelling power and starch solubility and increased thermal transition temperatures, enthalpy changes, pasting viscosities and in vitro digestibility. Annealing led to an increase in proportion of B-type polymorphs within C-type pea starches, which was explained as being due to a polymorphic transition from A to B. Annealing mainly acts on the amorphous regions of starch granules, leading to amylose leaching. The removal of amylose molecules can reduce the long-range forces within the granule and thereby weakening the overall granule structure and leading to significant changes to functional properties. This study showed that annealing is a mild but important physical modification of starch, which can be used as a pretreatment technique to tailor the starch functionality for specific industrial application.     

Leaching of residues of certain pesticides from black tea to brew

Tea is the most commonly consumed beverage in the world. It is prepared after infusing processed black tea in hot water. During the process of brewing, along with flavour and aroma, the residues of plant protection chemicals may also be transferred into the tea brew or infusion. The leaching of certain pesticides, such as ethion, endosulfan, dicofol, chlorpyrifos, deltamethrin, hexaconazole, fenpropathrin, propargite, quinalphos and lambdacyhalothrin from powdered black tea into the brew was studied. The rate of transfer of the pesticide residue from black tea to the hot brew was largely influenced by physicochemical parameters, such as water solubility and octanol-water partition coefficient. Tea brews prepared from untreated black tea samples were fortified with standard solutions of the respective pesticides, extracted and analysed using GC and HPLC by following standardised methods. Results revealed that the rate of leaching of residues of these pesticides into the tea brew was low due to their low solubilities in aqueous medium and high octanol-water partitioning coefficients.     

Effect of ionic gums and dry heating on physicochemical,morphological, thermal and pasting properties of water chestnut starch

Starch from water chestnuts (Trapa natans) was isolated and modified by dry heating and hydrocolloids [carboxy methyl cellulose (CMC) and sodium alginate]. Native and modified starches were evaluated for their physicochemical, pasting, thermal and morphological properties. Pasting and thermal properties were studied using Rapid Visco Analyzer (RVA) and Differential Scanning Calorimeter (DSC) respectively. Morphological properties were studied by Scanning Electron Microscopy (SEM). Modification of the starch by dry heating with and without gums reduced paste clarity and increased the water and oil binding capacity; solubility and swelling power decreased. Dry heating of native starch increased peak viscosity; however, with addition of CMC, peak viscosity decreased. Starch modified with CMC and 4 h heating exhibited lowest gelatinization temperature (T₀). Pasting characteristics of native water chestnut starch were largely affected by the addition of gums and/or heat treatment. Overall onset gelatinization temperature reduced with heat treatment and addition of gums. Morphological studies revealed no significant variation in starch granule size. Starch granules were seen agglomerated because of leaching of amylose and granule interspacing decreased with addition of gums.     

Enhanced Solubility and Ecological Impact of Atmospheric Phosphorus Deposition upon Extended Seawater Exposure

Atmospheric P solubility affects the amount of P available for phytoplankton in the surface ocean, yet our understanding of the timing and extent of atmospheric P solubility is based on short-term leaching experiments where conditions may differ substantially from the surface ocean. We conducted longer- term dissolution experiments of atmospheric aerosols in filtered seawater, and found up to 9-fold greater dissolution of P after 72 h compared to instantaneous leaching. Samples rich in anthropogenic materials released dissolved inorganic P (DIP) faster than mineral dust. To gauge the effect of biota on the fate of atmospheric P, we conducted field incubations with aerosol samples collected in the Sargasso Sea and Red Sea. In the Sargasso Sea phytoplankton were not P limited, and biological activity enhanced DIP release from aerosols, and aerosols induced biological mineralization of dissolved organic P in seawater, leading to DIP accumulation. However, in the Red Sea where phytoplankton were colimited by P and N, soluble P was rapidly consumed by phytoplankton following aerosol enrichment. Our results suggest that atmospheric P dissolution could continue over multiple days once reaching the surface ocean, and that previous estimates of atmospheric P deposition may underestimate the contribution from this source.     

Physico-chemical Characteristics of Starches from Chick Pea,Cow Pea and Horse Gram

Starches were isolated in 36, 37 and 28% yields, from chick pea, cow pea and horse gram, respectively. Study of their properties revealed mixed granule population; single stage swelling with high solubility in water for cow pea and horse gram starches in comparison to chick pea starch; slightly higher solubility in DMSO for chick pea starch followed by cow pea and horse gram starches; a relatively high viscosity in alkaline solution of cow pea starch; and Brabender amylograms indicating a low slurry viscosity and low set back in the case of chick pea starch compared to the other two starches which exhibited considerable peak viscosity as well as retrogradation. All the starches contained amylose in the range of 32 – 34%. X-ray powder patterns showed chick pea and horse gram starches to be of B-type, whereas cow pea starch was of A-type.     

Characterizing and designing polycation-clay nanocomposites as a basis for imazapyr controlled release formulations

A novel controlled release formulation (CRF) of the herbicide imazapyr (IMP) was designed to reduce its leaching,which causes soil and water contamination. The anionic herbicide IMP was bound to polydiallyldimethylammonium-chloride (PDADMAC)-montmorillonite composites. PDADMAC adsorption reached a high loading of polymer, which resulted in charge reversal of the clay and promoted IMP binding. The composites were characterized by Fourier transform infrared, zeta potential, and X-ray diffraction measurements, indicating electrostatic interactions of the polycation with the surface, polycation intercalation in the clay and suggesting a configuration as loops and tails on the surface at high loadings. IMP binding to the composites is affected by polycation loading and flocculation. Upon adding high concentrations of IMP to a composite of 0.16 g/g, we obtained high herbicide loadings (66% active ingredient). IMP release from the CRFs applied on a thin layer of soil was substantially slower than its release from the commercial formulation (Arsenal). Accordingly, soil column bioassays indicated reduced herbicide leaching (nearly 2-fold) upon applying the CRFs while maintaining good herbicidal activity. The new PDADMAC-clay formulations are promising from the environmental and weed control management points of view.     

The structure of starch granules in fried battered products

This work studies the structure of starch granules during different steps in the production of frozen battered squid rings, using image analysis and microscopy techniques. Frozen battered squid was prepared with four different batter formulations including wheat flour, corn flour, salt and leavening agent and subjected to pre-frying, freezing and final frying to obtain an industrial product. A control product for each of the formulations was prepared with no pre-frying and no freezing steps.The control products, regardless of their formulation, showed most starch components occluded into the starch granules, while the final products presented more leaching of starch components out of the granules. The use of corn flour as an ingredient increased the water retention capacity of the batter, resulting in higher area values for starch granules in formulations where this ingredient is used. There were significant differences between some formulations in the size and shape of the large starch granule population, but no significant differences were observed for the small granule population. As regards the preparation steps, short thermal treatments such as pre-frying mainly affected the large starch granules, which are weaker.     

Relative solubility of cations in Class F fly ash

Coal utilization byproducts (CUB), such as fly ash, contain cations that may be released during exposure to fluids such as acid rain or acid mine drainage. Researchers at the Department of Energy's National Energy Technology Laboratory (DOE/NETL) have conducted a long-term column leaching study of 32 Class F fly ash samples from pulverized coal (PC) combustion, and quantified the release of 19 cations in four leachants with a pH between 1.2 and 12. The relative solubility (M(L/T)) of each cation was defined as the total mass leached (M(L)) relative to the concentration (M(T)) of that element in the fly ash sample. A frequency distribution of relative solubility values was computed with ranges defined as insoluble, slightly soluble, moderately soluble, and very soluble. On the basis of this sample set, Ba, Cd, Fe, Pb, Sb, and Se in PC fly ash are insoluble. The elements Al, Be, Ca, Co, Cr, Cu, K, Mg, Mn, Na, Ni, and Zn are slightly to moderately acid soluble. Only Ca and Na are water soluble; As and Ca are soluble in the basic solution, The results of this study indicate that the extent to which cations in Class F PC fly ash can be leached by naturally occurring fluids is very limited.     

Initial Phase Solubilization of Normal Corn Starch by Methyl Sulfoxide (DMSO): Evidence from Scanning Electron Microscopy and Size Exclusion Chromatography

Initial structure and solubility changes of normal corn and starch granules, dispersed in varying methyl sulfoxide (DMSO) concentrations were investigated by scanning electron microscopy (SEM) and high-performance size exclusion chromatography (HPSEC). Larger granules from starches held for 6 or 15min and air dried showed increased surface etching with increasing DMSO concentration (0–70%): smaller granules showed surface peeling at 70% DMSO. At 90% DMSO, larger granules fractures into smaller pieces, while smaller granules showed full surface erosion. At 100% DMSO, large chunks eroded off both large and small granules. With 100% DMSO, a sheet-like layer formed over a mass of ruptured granules during drying, suggesting that in the absence of water, DMSO dissolves part of the granule, forming a viscous solution which may limit further DMSO granule dispersion. Granules processed with critical-point drying showed additional evidence of attack. HPSEC polymer solubility increased with DMSO concentration (0–90%). At 100% DMSO, however, there was no measured solubility. Similar solubilities for starches held at 6 or 15min (0–90% DMSO) suggest that DMSO may require an external force such as heat to facilitate polymer solubility. More amylopectin of a lower molecular weight was solubilized at 6min, while more amylose was solubilized at 15min. This suggests that granule surfaces were mostly composed of amylopectin under development, while amylose was mostly confined to amorphous regions inside the granule.     

Physicochemical characterization of collagen fibers and collagen powder for self-composite film production

The purpose of this work was to determine some physicochemical characteristics of collagen fibers and collagen powder obtained from bovine hides as potential raw materials for production of films with improved mechanical properties. These materials are collagen in its crude form, without the hydrolysis reaction that leads to gelatin production. The following analyses were carried out: proximate composition, amino acid composition, solubility in water, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), size distribution and moisture sorption isotherms. The collagen fibers and collagen powder showed practically the same protein content, and the only differences between them, apart from the particle shape and size, were in their solubility in water, which was probably partly due to differences in particle size. Due to their similar composition but different physical properties, collagen fibers and collagen powder were shown to be suitable for the production of biocomposite films where the powder is the basis of the film matrix and the fibers act as filler, exerting a reinforcement effect. Films with the protein content supplied by 50% collagen powder and 50% collagen fibers could be produced with the film thickness fixed at 180 μm and subjective evaluations suggested that the fibers remained completely involved in the filmogenic matrix.     

Gelatinization and Solubility Properties of Commercial Oat Starch

Gelatinization and solubility characteristics of starch contribute to unique functionality in foods. Corn and oat starch viscoamylographs (35g db) showed peak viscosities of 400 and 390B.U., respectively. Oat starch had a more rapid (89.7 vs 85.6°C) and higher set back (790 vs. 740B.U.) than corn. Data on soluble components of cooled (85°C) starch pastes, as collected and analyzed by high-performance size exclusion chromatography (HPSEC), suggest that amylopectin plays a significant (P<0.05) role in oat paste set back; for corn starch, amylose is the dominant factor. Solubilities and apparent molecular weights (MW) of oat starch heated (65-120°C) under shear and subsequent sonication (0-40s) in water or 90% methyl sulfoxide (DMSO) were also determined by HPSEC. An intermediate MW fraction was eluted on the HPSEC chromatograms only when oat starch was heated in water (100-120°C/30min) or DMSO and sonicated, suggesting that this fraction may not be inherent in the native granule. in water, polymer solubility and peak MW increased with temperature (65-120°C), whereas in DMSO, solubility decreased with heating (65-100°C), while peak MW remained basically constant. Aqueous (aq) leaching at 75°C solubilized more corn amylose than amylopectin, but amylopectin and amylose co-leached from oat starch granules. Aq leaching, at 20°C above their DSC peak ends (85 and 95°C for oat and corn, resepctively), showed more amylopectin leached from oat starch granules whereas more amylose was leached from corn starch granules.     

Persistence,penetration, and breakdown of chlorthiamid and dichlobenil herbicides in field soils of different types

The persistence, penetration, and breakdown of the herbicides chlorthiamid (‘Prefix’, 2,6-dichlorothio-benzamide) and dichlobenil (‘Casoron’, 2,6-dichlorobenzonitrile) have been studied in the field in clay, medium loam, sandy loam, and peat using applications of unincorporated granules and wettable powders at 9 kg/ha (active material). Conversion of chlorthiamid to dichlobenil was rapid in the soil. After 4 weeks, less than 3% remained of chlorthiamid that was applied to clay, medium loam, and sandy loam and less than 17% remained in peat. The initial half-life of dichlobenil residues (following dichlobenil application) and ‘total nitrile’ residues (chlorthiamid + dichlobenil residues following chlorthiamid application) under wet conditions was near 2 weeks in clay, medium loam, and sandy loam, and ranged from 3-20 weeks in peat for different applications. There was very little penetration of chlorthiamid or dichlobenil below the 4 in depth of the soil within 32 weeks of the single application of herbicides except in peat. 2,6-Dichlorobenzamide was formed in all four soil types after application of either chlorthiamid or dichlobenil. At 8-10 weeks after application the benzamide residues in the soil were generally greater than those of the dichlobenil, except in peat. In clay, which was studied in most detail, the benzamide penetrated to greater depths than did the dichlobenil or chlorthiamid.     

CHANGES IN PARTITION COEFFICIENTS of ALCOHOLS AS AFFECTED BY the PRESENCE of VARIOUS FOOD SOLIDS

Using homologous series of alcohols and varing temperatures, it has been demonstrated in this study that volatility of alcohols increases upon changes in the system which decrease their solubility in the liquid. Addition of solutes has various effects on volatility, depending upon their ability to interact with water and volatiles. Surface characteristics, including the number of binding sites and surface area, significantly affect interaction. When more than one type of solids is present, alcohols preferentially adsorb to the solid with higher affinity for alcohols, until all binding sites on the solid are occupied. Silica and soy protein increase solubility of alcohols in water by adsorbing them through hydrophobic association and/or hydrogen bonds. Sodium silicoaluminate, xanthan gum and, to some extent, maltodextrin show less interaction with alcohols than with water.     

Studies on Rye Starch Properties and Modification. Part II: Swelling and Solubility Behaviour of Rye Starch Granules

Rye starch shows the typical inhibited swelling behaviour of triticeae starches with an onset of swelling at rather low temperature (50–55°C). Swollen rye starch granules exist as individuals even after swelling at 100°C. The total dispersion of rye starch needs temperatures above 120°C with pressure cooking. On heating of the rye starch suspension preferentially amylose is leached. Defatting of rye starch exhibits no influence on swelling power but results in higher solubility and in increased amylose leaching. The drying procedures applied here resulted in stronger assoziation of the polymer molecules in the starch granule leading to higher swelling temperatures and a reduced solubility. Shiftings of the crystalline/ amorphous-ratio of the starch granules as caused by different drying procedures, had no influence on the results of swelling power investigation but the highest swelling enthalpy as well as Brabender viscosity were exhibited by a sample dried at room temperature. It is proved to be possible to change the swelling behaviour of rye starch to “potato starch type” by slight chemical modification like succination.     

导热填料改性烟草颗粒的热解和释烟特性

为揭示加热不燃烧状态下导热填料对烟草颗粒热解和释烟特性的影响规律,利用导热系数测试仪、热分析仪（TGA）和锥形量热仪（CONE）,研究了不同含量和种类的导热填料对烟草颗粒导热系数、热解过程以及烟气释放过程的影响。结果表明:①随碳酸钙（CaCO₃）粉体质量分数增加,烟草颗粒导热系数增大。20%添加量下填料发生自团聚,导热系数略有降低。晶须可有效改善填料在基材中的自团聚现象。碳化硅（SiC）较CaCO₃对导热系数的提升更明显。②相较于对照样品,添加导热填料后,烟草颗粒微分热重（DTG）曲线向低温区移动,整体上导热性越高,移动幅度越大,最大失重速率越大。不同升温速率下,具有最大导热系数样品的DTG曲线始终位于对照样的低温侧;且随升温速率增大,其与对照样热解特征参数的差值逐渐缩小,导热性差异对烟草颗粒热解过程的影响程度减小。③相较于对照样品,添加导热填料后,烟草颗粒起始释烟速率增大;随导热性提高,最大释烟速率增大,烟气释放过程集聚。CO与CO₂的释放速率随导热性提高明显增大,说明烟草颗粒的热解程度加剧,但提高导热性易造成热量集聚,使烟草颗粒发生燃烧。      

石膏晶须的溶解抑制改性及在造纸中的应用

石膏晶须是一种优质的造纸填料,但其溶解性较大,直接用于造纸很容易造成石膏晶须的损失。本文主要探讨了使用壳聚糖涂覆石膏晶须的改性方法、改性后石膏晶须在水中的溶解性以及石膏晶须在造纸中的应用。实验得出:使用壳聚糖涂覆石膏晶须的改性方法是可行的,经此种方法改性的石膏晶须,其在水中的溶解量显著降低。对比未改性的石膏晶须,改性石膏晶须的填料留着率明显增大。同时随着填料留着率的增加,纸页耐破度有所下降,耐折度有所增大,撕裂度和抗张强度则随着改性石膏晶须涂覆量的不同而变化。当壳聚糖涂覆量为石膏晶须的2%时,填料的留着率最高,为未改性填料的3.6倍,但各强度指标除耐折度外均有所下降;而用4%的壳聚糖涂覆量改性时,石膏晶须的留着率为未改性前的2.2倍,且各强度指标(除耐破度外)均有所上升。     

Chromium release from waste incineration air-pollution-control residues

Cr release overtime was investigated in batch experiments for eleven air-pollution-control residues from eight different municipal solid waste incinerators covering all majorflue gas cleaning technologies. Cr released during 168 h of contact with water showed significant variations among the residues studied. Also for the individual residue, large variations were observed depending on the liquid-to-solid ratio used in the leaching test and the degree of carbonation. It is argued that Al(0) present in the residues can control Cr leaching by reducing Cr(VI) released from the solid phase by dissolution and that exposure to oxygen-either prior to or during the leaching test-depletes the reduction capacity of Al(0) leading to increased Cr leaching. A dynamic model is shown to describe Cr release from all investigated residues by accounting for Al(0) oxidation with Cr(VI), O2, and water as well as Cr(VI) dissolution. The paper reveals that Al-O2-Cr(VI) interactions must be considered very carefully when interpreting Cr leaching data.