Gley morphology and soil water regimes in some soils in south-central england

A good correlation was observed between the development of gley morphology and period of saturation at a depth of 38 cm in 44 soil profiles from south-central England. Gley morphology in the surface horizon (13 cm depth) was a less reliable indicator of waterlogging. Drainage class assignment based on morphological evidence produced effective separation of soils based on their water regimes, characterised by the period of saturation at 38 cm. Although the relationships observed are probably restricted to soils developed on similar parent materials, the subjective identification and assessment of gley morphology may be an alternative to the absolute colour criteria currently used in many soil classification schemes.     

Isozyme variation in some races of maize from Argentina

Summary Forty one populations of sixteen Argentine races of maize were studied with electrophoretic techniques. Seven isozyme systems coded by fifteen gene loci were used for studying the genetic variability within and among races and populations. In the whole sample was found that the variation within populations represented 78% of the isozymic variability, the variation among races was 14% while the variation among populations within races was only 8%. Cluster analysis and Principal Component analysis indicated that most races were closely related. Cateto Amarillo, Cravo and Perla Mediano were the most distinctive of the Argentine races.Germplasm Paper no. 10     

Extraction of phosphate from some phosphatic compounds

Abstract

Some of the common methods used for the evaluation of available phosphate in soils were studied with respect to their power of releasing phosphate present in certain phosphatic compounds and in the sorbed form. Considerable differences in the amounts extracted were observed, The anion resin extracted relatively larger quantities from Ca than from Al or Fe phosphate materials. EDTA extracted very small amounts from the Al‐phosphates in comparison with the amounts obtained from the Ca and the iron materials. Ammonium fluoride at low pH released considerable amounts of phosphate from all the phosphate materials including sorbed phosphate. The quantities of phosphate extracted by sodium bicarbonate and water were relatively low as well as those determined by isotopic exchange.     

砂滤罐处理工厂化养鱼循环水效果

根据石英砂粒径与颗粒密度的关系,研究砂滤罐处理工厂化养鱼循环水效果,该试验采用了2组并联的3层滤料普通砂滤罐,根据几何、物理原理,以石英砂最大颗粒密度,粒径3 mm作为中层,粒径2 mm和5 mm作为上下层,且颗粒密度均小于中层的设计。进行砂滤罐工厂化循环水处理效果和反冲洗再生效果的试验,结果表明：悬浮物去除效果极为显著（P＜0.01）,去除率达99.83%,达到了去除悬浮物的要求。砂滤罐经过反冲洗后,能够再生使用。     

An evaluation of some fluorescent and non-fluorescent dyes in the identification of water transmission routes in soils

Two fluorescent dyes, sulpho-rhodamine B and lissamine yellow FF, and three non-fluorescent dyes, chlorantine fast green, sirius red and Chicago blue are compared for use in the identification of water transmission routes in structured soils. Subsequent to the flow of labelled water, a microsampling and extraction technique is employed to identify dye distribution in relation to structural features. The desirable properties of the dyes tested include stability over a wide pH range, anionic character and high molecular weight, the latter to reduce lateral diffusion from the transmission route. In these aspects they provide suitable alternatives to fluorescein and pyranine used by previous workers. The fluorescent dye lissamine yellow FF was found to be the most suitable for tracing rapidly moving water under field conditions. The transmission routes identified in field soils were associated with structural features readily recognized by routine soil survey techniques.     

Fibrous goethite in some soils from Japan and Scotland

Fibrous particles 20—50Å wide and several μm long have been found in the clay fractions from a number of Japanese and Scottish soils. The particles dissolved in buffered dithionite and hot acid oxalate (0.15 M) but were resistant to hot alkali (2% Na₂CO₃, 0.5 M NaOH) and acid (0.1 M HCl) treatments, suggesting a ferruginous and crystalline nature. The ferruginous nature was further indicated by energy-dispersive X-ray spectroscopy, which, at the same time, showed the presence of large quantities of Al and some Si. Electron diffraction analysis indicated goethite of low crystallinity as the most likely mineral. Incorporation of numbers of Al ions in the crystal lattice was inferred from the results of elemental analysis after chemical dissolution treatments.     

Volatilization of ketones from water

The overall mass-transfer coefficients for the volatilization from water of acetone, 2-butanone, 2-pentanone, 3-pentanone, 4-methyl-2-pentanone, 2-heptanone, and 2-octanone were measured simultaneously with the oxygen-absorption coefficient in a laboratory stirred water bath. The liquid-film and gas-film coefficients of the two-film model were determined for the ketones from the overall coefficients, and both film resistances were important for volatilization of the ketones. The liquid-film coefficients for the ketones varied with the 0.719 power of the molecular-diffusion coefficient, in agreement with the literature. The liquid-film coefficients showed a variable dependence on molecular weight, with the dependence ranging from the ?0.263 power for acetone to the ?0.378 power for 2-octanone. This is in contrast with the literature where a constant ?0.500 power dependence on the molecular weight is assumed. The gas-film coefficients for the ketones showed no dependence on molecular weight, in contrast with the literature where a ?0.500 power is assumed.     

Trace Element Emissions from some Cement Plants in Turkey

The cement industry has been one of the major sources of air pollution in the past and the Turkish Air Quality Protection Regulation has issued limits also to trace elementemissions to minimise the polluting effects of this industrialsector. In the present study, dust samples were obtained isokinetically from 18 main stacks of 10 cement plants locatedin different geographical areas of Turkey. The samples were analysed for trace elements Hg, Cd, Cr, Pb, Ni, Se, Te, TI, V, Sb, Ba, Zn, Co, Sr, Cu, Bi, Mo, Be, and As. The results are presented both as concentration in the dust samples as well as emissions per unit production, and concentration inthe stack gas. The trace element emissions of the main stacksagree to great extent with the values given in the literature. On the other hand, the trace element emissions of the plants considered are well below the limits set in the Turkish Air Quality Protection Regulation.     

Volatilization of organic chemicals from water

Liquid-phase transfer coefficients of ten selected organic pollutants were measured simultaneously with the O₂ reaeration coefficient in a 2L reactor. The contents of the reactor were stirred in the laboratory by a 0.15 m diameter propeller attached to a constant speed motor. The ratio of the mass transfer coefficient of the chemical to that of O₂ is found to vary between 0.43 and 0.60 for eight of the chemicals tested. This result is in good agreement with the literature concerning high volatility chemicals. The value of this ratio for the other two chemicals was found to be 0.10 for nitrobenzene and 0.01 for phenol, confirming the predominance of gas phase resistances in the transport process for these two compounds.     

Release of potassium from some benchmark soils of India

Release of potassium from 15 surface samples of benchmark Alluvial, Red and Black soils of India to 0.01 M solutions of BaCl₂, CaCl₂, NH₄Cl and NaCl was studied in soils either untreated or pretreated with 5 × 10⁻³ M KCl. In the untreated soils, the efficacy of the extractants declined in the sequence: BaCl₂ > NH₄Cl > CaCl₂ > NaCl. Cumulative K-release was greatest from Black soils, followed by Red and Alluvial soils. From soils pretreated with 5 * 10⁻³ M KCl, more K was released than retained, and more 'native' K was released than that from untreated soils. Increase in the release of 'native' K decreased in the sequence: Red > Alluvial > Black soils. The amounts of surface and internal K, desorption rate constants and parabolic diffusion constants were calculated from K release to the various electrolytes.     

Selenium enrichment of tea from some areas of China

The levels of selenium (Se) in soils and rocks and Se enrichment of tea as well as factors affecting Se extraction rate from tea were studied. The Se content for 133 tea samples varied from 0.021 to 0.774 mg kg^‐1 with a minimum value of 0.017 mg Se kg^‐1 while some other teas had a maximum value of 4.32 mg Se kg^‐1. The Se content of tea was in a logarithmic normal distribution, and its geometric mean value was 0.120 mg Se kg^‐1. The Se content of soil parent materials and rocks were highly correlated with the Se content in tea leaves. Rock stratum rich in Se occurred in Paleozoic siliceaus shales and carbonaceous‐siliceaus shales of the Permian, Ordovician, and Cambrian periods. Total Se extraction rate of tea in three extractions was 25.6% (black tea and green tea were 24.9% and 26.2%, respectively), and the extraction rate for the first, second, and third times were 50.9%, 27.3%, and 21.8% of the total Se extracted, respectively. Based on factors, such as the Se content in tea, daily quantity of tea drunk, Se extraction rate of tea, and the normal Se dietary requirement, we would suggest that the Se index for tea rich in Se is within the range from 0.40 to 1.55 mg Se kg^‐1.     

Composition of iron-manganese concretions from some New Zealand soils

A selection of iron-manganese concretions from five reference soil profiles and a buried loess deposit in New Zealand have been studied. Concretions appear to have developed by the precipitation of amorphous iron and manganese oxides among soil particles. X-ray fluorescence analysis shows that the concentrations of Fe, Mn, Co and Ba in the concretions are generally higher, and those of K, Ca, Si, and Al are generally lower, than in the soil materials surrounding the concretions, whereas Ti, Zn, S, and P show little variation. Other approximate analyses indicate that Cu, Ni, Mo, V, and Pb tend to be concentrated in concretions but for Ga, Zr, Sr, Li, and Rb there was no discernible trend. Electron probe microanalyses of some concretions show that Co and Ba are concentrated in Mn-rich phases rather than Fe-rich phases.Comparison with published results for concretions (Mn nodules) from the ocean floor and the floor of Lake Ontario indicates that, on average, marine concretions have higher Mn, and lower Si and Al concentrations than soil concretions, and that marine concretions have lower Fe concentrations than either Ontario or soil concretions.     

Focused microwave assistance for extracting some pesticide residues from strawberries into water before their determination by SPME/HPLC/DAD.

A novel and simple method for the determination of some pesticide residues in strawberries using both focused microwave-assisted extraction (FMAE) and solid-phase micro extraction (SPME), coupled with high-performance liquid chromatography (HPLC), has been developed. The pesticides were first extracted from strawberries with water and the assistance of focused microwaves at 30 W for 7 min. Then, an aliquot of the resulting aqueous extract was subjected to SPME with a 60-microm thick poly(dimethylsiloxane)/divinylbenzene (PDMS/DVB) fiber for 45 min at room temperature, with the solution being stirred at 1000 rpm. The extracted pesticides on the SPME fiber were desorbed into the SPME/HPLC interface for quantitative analysis with a diode array detector (DAD). The whole sample pretreatment procedure before chromatographic analysis did not use any organic solvents or involve any blending or centrifugation steps. The five compounds (carbendazim, diethofencarb, azoxystrobine, napropamide, and bupirimate) were chosen because they cannot be analyzed easily by GC. The efficiency of this relatively fast procedure was comparable to that of previously reported methods, with detection limits at low microg/kg levels and linear responses in the range from 0.05 to 1 mg/kg of pesticide in strawberries, with RSDs between 3 and 7.3%, depending on the analyte. In all but one case results obtained by this method for field-incurred samples were comparable to those obtained with traditional methods.     

Fractionation of soil cadmium from some new zealand soils

Abstract

The concentrations and forms of soil cadmium (Cd) in 12 different New Zealand topsoils were investigated using a sequential fractionation procedure. Total soil Cd concentrations were low and ranged between 0.03 μg g^‐1 to 1.34 μg g^‐1 and were highly correlated with total soil phosphorus (r²=0.85, P<0.01). Results indicated that there was a wide range in the concentrations of Cd associated with individual soil fractions and large variations between soils. On average for all soils, the smallest proportion of Cd was in exchangeable forms, i.e., 3%, with 12% in the crystalline oxide fraction, 13% in the amorphous oxide fraction and the greatest proportion of Cd associated with the organic 34% and residual 38% fractions. There was evidence to show that a soil extractant which is commonly used to predict plant uptake of Cd from soils, i.e., 0.04 M ethylene diamine terra acetic acid (EDTA), extracts Cd from both exchangeable and organic forms of soil Cd.     

Cadmium leaching from some New Zealand pasture soils

Cadmium (Cd) inputs and losses from agricultural soils are of great importance because of the potential adverse effects Cd can pose to food quality, soil health and the environment in general. One important pathway for Cd losses from soil systems is by leaching. We investigated loss of Cd from a range of contrasting New Zealand pasture soils that had received Cd predominantly from repeated applications of phosphate fertilizer. Annual leaching losses of Cd ranged between 0.27 and 0.86 g ha^–l, which are less than most losses recorded elsewhere. These losses equate to between 5 and 15% of the Cd added to soil through a typical annual application of single superphosphate, which in New Zealand contains on average 280 mg Cd kg^?1 P. It appears that Cd added to soil from phosphate fertilizer is fairly immobile and Cd tends to accumulate in the topsoil. The pH of the leachate and the total volume of drainage to some extent control the amount of Cd leached. Additional factors, such as the soil sorption capacity, are also important in controlling Cd movement in these pasture soils. The prediction of the amount of Cd leached using the measured concentrations of Cd in the soil solution and rainfall data resulted in an overestimation of Cd losses. Cadmium concentrations in drainage water are substantially less than the current maximum acceptable value of 3 µg l^?1 for drinking water in New Zealand set by the Ministry of Health.     

窑窖滴灌系统输水管路的优化布置

窑窖集雨滴灌成为解决我国干旱半干旱地区水资源短缺的途径之一。该文分析了窑窖分散式水源特点：水量较小，零星分布，管道设计困难，系统管理繁杂。以在农作物缺水关键期进行灌溉为出发点，根据水窖和地块分散的特点，通过对水窖输水线路优化设计，降低灌溉的管理和工程造价，设计最佳滴灌输水路线，达到水源联合调度的目的，并与传统设计方法和图论优化设计法进行了比较。所提出的设计方法适合解决各种地形条件下分布水源的输水路线布置问题。