Speciation and release kinetics of zinc in contaminated paddy soils

Zinc is an important nutrient for plants, but it can be toxic at high concentrations. The solubility and speciation of Zn is controlled by many factors, especially soil pH and Eh, which can vary in lowland rice culture. This study determined Zn speciation and release kinetics in Cd-Zn cocontaminated alkaline and acidified paddy soils, under various flooding periods and draining conditions, by employing synchrotron-based techniques and a stirred-flow kinetic method. Results showed almost no change in Zn speciation and release kinetics in the two soils, although the soils were subjected to different flooding periods and draining conditions. The mineral phases in which Zn is immobilized in the soil samples were constrained by linear least squares fitting (LLSF) analyses of bulk X-ray absorption fine structure (XAFS) spectra. Only two main phases were identified by LLSF, i.e., Zn-layered double hydroxides (Zn/Mg-hydrotalcite-like, and ZnAl-LDH) and Zn-phyllosilicates (Zn-kerolite). Under all soil pHs, flooding, and draining conditions, less than 22% of Zn was desorbed from the soil after a two-hour desorption experiment. The information on Zn chemistry obtained in this study will be useful in finding the best strategy to control Cd and Zn bioavailability in the Cd-Zn cocontaminated paddy soils.     

Modeling kinetics of Cu and Zn release from soils

Kinetics of Cu and Zn release from soil particles was studied using two surface soils with a stirred-flow method. Different solution pH, dissolved organic matter (DOM) concentrations, and flow rates were tested in this study. A model for kinetics controlled sorption/desorption reactions between soils and solutions was globally fit to all experimental data simultaneously. Results were compared to a model that assumes local instantaneous equilibrium. We obtained one unique set of model parameters applicable to different pH, dissolved organic carbon (DOC), and flow conditions. We included DOM complexation of copper ions, which decreased their sorption. The effect of pH was included by assuming proton competition with metal ions for binding sites on soil particles. These results provide the basis for developing predictive models for metal release from soil particles to surface waters and soil solution.     

Effects of some cations on the formation of acrylamide and furfurals in glucose–asparagine model system

A recent patent application and some other studies showed that there is a relation between acrylamide formation and cations. In fact, to date, there is no concrete evidence on the formation or elimination of some compounds in foods and current hypotheses are based only on observations in model systems. To find that this is a logical explanation, we conducted a series of experiments, to show (i) the formation and the elimination of acrylamide with the addition of some cations, and (ii) the formation of hydroxymethylfurfural and furfural in a glucose–asparagine model system. The results indicated that the presence of cations reduced acrylamide formation, but increased hydroxymethylfurfural and furfural formation during heating. There was strong evidence that the cations effectively prevented the formation of Schiff base, which is the key intermediate leading to acrylamide, and mainly changed the reaction path toward the dehydration of glucose leading to hydroxymethylfurfural and furfural.     

不同体色烟蚜的消长动态及对药剂的敏感性

对江淮烟区未施药烟田中烟蚜的发生情况进行了２年调查，结果表明，烟蚜种群数量消长呈明显的双峰型；红色烟蚜在第２个高峰期是主要类型。同时用浸渍法分别检测了红、绿色烟蚜对３种药剂的敏感性，发现红色烟蚜敏感性低。     

Agriculture group and the british society of soil science symposium. Soil microbiology in relation to current problems

The following are summaries of papers and posters presented at a joint meeting of the Agriculture Group and the British Society of Soil Science held at the Society of Chemical Industry, 14 Belgrave Square, London SW1X 8PS on 18 November 1980. The papers so published are entirely the responsibility of the authors and in no way reflect the views of the Editorial Board of the Journal of the Science of Food and Agriculture.     

Comparing WHAM 6 and MINEQL+ 4.5 for the chemical speciation of Cu2+ in the rhizosphere of forest soils

Metal speciation data calculated by modeling could give useful information regarding the fate of metals in the rhizospheric environment. However, no comparative study has evaluated the relative accuracy of speciation models in this microenvironment. Consequently, the present study evaluates the reliability of free Cu ion (Cu2+) activity modeled by WHAM 6 and MINEQL+ 4.5 for 18 bulk and 18 rhizospheric soil samples collected in two Canadian forested areas located near industrial facilities. The modeling of Cu speciation was performed on water extracts using pH, dissolved organic carbon (DOC), major ions, and total dissolved Al, Ca, Cu, Mg, and Zn concentrations as input data. Four scenarios representing the composition of dissolved organic substances using fulvic, humic, and acetic acids were derived from the literature and used in the modeling exercise. Different scenarios were used to contrast soil components (rhizosphere vs bulk) and soil pH levels (acidic vs neutral to alkaline). Reference Cu2+ activity values measured by an ion-selective electrode varied between 0.39 and 41 nM. The model MINEQL+ 4.5 provided good predictions of Cu2+ activities [root-mean-square residual (RMSR)= 0.37], while predictions from WHAM 6 were poor (RMSR = 1.74) because they overestimated Cu complexation with DOC. Modeling with WHAM 6 could be improved by adjusting the proportion of inert DOC and the composition of DOC (RMSR = 0.94), but it remained weaker than predictions with MINEQL+ 4.5. These results suggested that the discrepancies between speciation models were attributed to differences in the binding capacity of humic substances with Cu, where WHAM 6 appeared to be too aggressive. Therefore, we concluded that chemical interactions occurring between Cu and DOC were key factors for an accurate simulation of Cu speciation, especially in rhizospheric forest soils, where high variation of the DOC concentration and composition are observed.     

The wax fraction of soils: Separation and determination of some components

Resin- and asphalt-free wax components from a mineral soil and from a peat were separated into free acids, esterified acids and unsaponifiable material. The acids, as methyl esters, were fractionated by column chromatography on magnesium trisilicate to yield n-alkanoic- and hydroxy-acid fractions. The unsaponifiable material was fractionated on activated alumina, and fractions consisting of n-alkanes, n-alkan-2-ones (methylalketones) and primary n-alkanols were obtained. Gas chromatography was used to separate and determine individual components. The n-alkanoic acid fractions contained members with both odd and even numbers of carbon atoms ranging from C₁₈ to C₃₄ but with the latter predominating (80-90%). The carbon number of the n-alkanes and n-alkane-2-ones covered a similar range in which the odd-numbered members predominated (80-90%). The primary alcohols had a slightly lower average chain length (C₁₆- C₃₀) and 90% consisted of even-numbered members. These fractions together accounted for 25–30% of the resin- and asphalt-free wax.     

A method for separating the hydrolysis products of monocalcium phosphate to test their effects on soils and crops

A method was developed to test separately on crops the compounds formed when a granule of concentrated superphosphate hydrolyses in soil. An amount of monocalcium phosphate (MCP) equal to that in a granule of superphosphate was placed in a small glass tube with glass fibre filter paper on its base; a moist plug was put in the top of the tube which was placed on moist soil in a pot; the whole was covered and left for six days. MCP hydrolysed and triple-point solution moved into the soil. The residue in the glass tube was transferred to another pot. In laboratory experiments the composition of the residue was that of dicalcium phosphate showing that the products of hydrolysis were like those from MCP hydrolysed in concentrated solution. Movement of the triple-point solution in soil was similar to that in experiments made by Tennessee Valley Authority.     

Phosphorus sorption by some coconut-growing acid soils of Sri Lanka and its relationship to selected soil properties

Phosphorus (P) sorption in the presence of 10^?2M calcium chloride by ten coconut-growing acid soil samples of Sri Lanka belonging to the Ultisol, Alfisol and Entisol orders was evaluated using the Langmuir sorption isotherm. The data for all samples fitted the single-site Langmuir sorption isotherm when equilibrium P was less than 1 μg ml^?1, but showed some deviations at larger concentrations of P. A two-site Langmuir sorption isotherm was successfully used to describe the sorption data of three samples at these high concentrations. The single-site Langmuir sorption maxima were greater for Ultisols (349–825 μg g^?1) than for the other soils (136–345 μg g^?1). These sorption maxima were significantly correlated with %-clay, %-silt, dithionite-extractable iron, and 1M ammonium acetate (pH 4.8)-extractable aluminium. Regression analysis of P sorption on different forms of iron (Fe) and aluminium (Al) indicated that crystalline ‘free Fe oxides’ (dithionite-extractable Fe minus 0.3M oxalate-extractable Fe) and ‘active Al’ which consists of hydroxy Al monomers and polymers [1M ammonium acetates, (pH 4.8)-extractable Al minus 1M potassium chloride extractable Al] were the important factors contributing towards P sorption.     

Fluoride content of some common South Indian foods and their contribution to fluorosis

Fluoride contents of 98 food items commonly used in South India were determined with special reference to the feeding habits of remote rural populations in 41 villages of Anantapur District, Andhra Pradesh, India, where dental and skeletal fluorosis is endemic. Fluoride up to 4.5 mg kg^?1 was found in irrigation and drinking water supplies. Thirty-two locally grown food items had generally higher fluoride contents (ranging jiom 0.2 to 11.0 mg kg^?1) with the notable exception of coconut water where even traces of fluoride could not be detected. The combined daily intake of fluoride jiom food and drinking water in the local population was found to range jiom 2.2 mg to 7-3 mg (0.05–0.32 mg kg^?1 BW). The role played by food composition, cooking habits of the local population, general poverty and illiteracy in contributing to the prevalence of fluorosis in schoolchildren in the age group 6–18 years (even in areas with drinking water supplies within the permissible levels as per WHO standards) is discussed.     

Dietary exposure to metals and other elements in the 2006 UK Total Diet Study and some trends over the last 30 years

Concentrations of 24 elements including metals in the 2006 UK Total Diet Study (TDS) were measured and dietary exposures estimated. Composite samples for the 20 TDS food groups (bread, fish, fruit, etc.) were collected from 24 UK towns and analysed for their levels of aluminium, antimony, arsenic, barium, bismuth, cadmium, chromium, copper, germanium, indium, lead, manganese, mercury, molybdenum, nickel, palladium, platinum, rhodium, ruthenium, selenium, strontium, thallium, tin, and zinc. Concentrations of each of the elements in the food groups were lower than or similar to those reported in the previous TDS survey, conducted in 2000, with the exception of aluminium, barium, and manganese. Dietary exposures to the 24 elements were estimated for UK consumers and compared with previous estimates made over the last 30 years in order to examine any trends in exposure to these elements in the typical UK diet. Population exposures to the elements have generally declined over time, and exposures to most of these elements remain at low levels. The independent UK Government scientific Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) commented on the estimated dietary exposures, taking into account their previous evaluations (in 2003 and 2008), and identified no major concerns for the health of consumers, but did advise that there was a need for more information on aluminium and barium, and also commented that dietary exposure to inorganic arsenic and to lead should continue to be reduced.     

Contribution of some volatile tomato components and their mixtures to fresh tomato aroma

Some volatile components of fresh tomatoes and mixtures of these components were evaluated for their contribution to fresh tomato aroma. cis-Hex-3-enal was the only individual component evaluated which was rated moderately similar to the aroma of fresh tomatoes. A mixture of cis-hex-3-enal, 2-methylhept-2-en-6-one, eugenol and β-ionone significantly improved the aroma of tomato juice prepared from foam-mat-dried tomato powder. Since the individual components of the mixture did not give significant improvement, the desired effect probably occurred as a result of a complex interaction among the added components and juice.     

若干模糊蕴涵及其性质分析

分析若干常见模糊蕴涵的定义和性质.以检验模糊蕴涵算子的19条性质为出发点,引入若干常见模糊蕴涵的定义,提出推理蕴涵、基本蕴涵和保值蕴涵等概念;对常见蕴涵的性质进行分析,比较了它们的关系;探讨19条性质的独立性,得到如果I满足Ⅰ10,Ⅰ11和Ⅰ16,则I满足Ⅰ1~Ⅰ19,且Ⅰ10,Ⅰ11和Ⅰ16是相互独立的.     

Application of capillary electrophoresis to determine metal cations,anions, organic acids,and carbohydrates in some Pinot Noir red wines

Capillary electrophoresis was used for determination of inorganic alkali and alkali earth metal cations, inorganic anions, anions of organic acids, and carbohydrates in six Pinot Noir grape red wines. Spectrum analysis was applied to evaluate the possible chemical differences between the wines from different geographic origin. In addition, sensory evaluation was used to reveal differences between wines from the end user point of view. Both chemical analyses and the sensory evaluation revealed clear differences among the wine samples. The total concentrations of inorganic ions, carboxylate anions, and carbohydrates varied 1.9–3.1 g L⁻¹, 4.3–5.5 g L⁻¹, and 1.5–7.5 g L⁻¹, respectively. Although the grape was same in all samples, the results show considerable variations in chemical composition, the red wine from Tasmanian being the most different among samples.     

PBDEs in European background soils: levels and factors controlling their distribution

Surface soils (0-5 cm) from remote/rural woodland (coniferous and deciduous) and grassland locations on a latitudinal transectthrough the United Kingdom and Norway were analyzed for polybrominated diphenyl ethers (PBDEs). Concentrations ranged between 65 and 12 000 sigma(ALL)PBDE ng kg(-1) dry weight. PBDE-47, -99, -100, -153, and -154-the major constituents of the penta-BDE technical product-dominated the average congener pattern of the soils. Indeed, the average congener composition and distribution measured in these European background soils closely matched that reported in the technical penta-BDE product. This is interpreted as evidence that transfer of the congeners present in penta-BDE-treated products from source-air-soil occurs with broadly similar efficiency, perhaps because there has been little weathering/degradation/alteration of the congener source pattern by processes operating during atmospheric transport or within the soil itself. BDE-183, a marker for the octa-BDE mix, was detected at concentrations ranging from <9 to 7000 (median approximately 50 ng kg(-1)). In most soils, it made a minor contribution to the sigma(ALL)PBDE concentration, but it was a major component in some samples from northern England. Forest soils tended to have higher concentrations than grasslands. Underlying the average soil composition, some differences in the congener pattern were observed. Notably, there was evidence of latitudinal fractionation, with the relative contribution of PBDE-47 and lighter congeners to the sigmaPBDE increasing northwards (with increasing distance from source areas), while the proportion of PBDE-99 and heavier congeners decreased. Plots of concentration against percentage soil organic matter had different slopes for different congeners. Higher slopes were generally seen for the lighter PBDEs (e.g., PBDE-47), indicating that they have undergone some air-surface exchange (hopping), while the slopes of heavier congeners (e.g., PBDE-153) were close to zero, indicating that they are retained more effectively by soils after deposition.     

Organic phosphorus in some northern nigerian soils in relation to soil organic carbon and as influenced by parent rock and vegetation

The distribution of organic phosphorus in relation to soil organic matter and the influence of parent material and vegetation of organic P level was studied in a number of soil profiles in the northern half of Nigeria. There was a close relationship between soil organic carbon and organic phosphorus contents of these soils. The ratios of these two ingredients were all less than 200:1. This fact suggests that organic P is likely to be mineralised. The effect of parent rock on organic P contents was slight, but there was an indication that soil profiles on metamorphic parent rocks contained more organic phosphorus than those on sedimentary parent material. Vegetation had a great influence on organic P as shown by the relatively higher organic phosphorus contents of profiles from southern Guinea savanna and the lower contents of the Sudan vegetation zone. The profiles from impeded drainage sites (fadamas) were generally richer in organic phosphorus than were those from comparable vegetation zones on well drained sites.     

H+-ATPase activity in Bifidobacterium with special reference to acid tolerance

The acid tolerance of 17 strains of nine species of bifidobacteria was compared using brief exposures to acidic conditions (pH 2-5). In addition, because it has been hypothesized that the acid tolerance of bifidobacteria depends on H+-ATPase activity, the activity of this enzyme in various strains and species was compared. In general, the acid tolerance of bifidobacteria was found to be weak, with the exception of Bifidobacterium lactis and Bifidobacterium animalis. High numbers of all strains of B. lactis and B. animalis survived exposure to pH 3-5 for 3 h. The H+-ATPase activity of the acid-tolerant strains B. lactis LKM512 and JCM 10602T, and B. animalis JCM 1190T, JCM 1253, JCM 7117, and JCM 7124 was higher at pH 4 than at pH 5. In contrast, the H+-ATPase activity of nonacid-tolerant strains was lower at pH 4 than at pH 5.     

Total protein and amino acids contents of some common foods in South East Asia

Analyses of amino acids and total protein have been carried out on some common foods in South East Asia including instant noodles, soy milk, soy sauce, bird's nest and shark's fin.