Application of Electrochemical Degradation of Wastewater Composed of Mixtures of Phenol–Formaldehyde

The industrial wastewater from resin production plants contains as major components phenol and formaldehyde, which are traditionally treated by biological methods. As a possible alternative method, electrochemical treatment was tested using solutions containing a mixture of phenol and formaldehyde simulating an industrial effluent. The anode used was a dimensionally stable anode (DSA?) of nominal composition Ti/Ru_0.3Ti_0.7O₂, and the solution composition during the degradation process was analyzed by liquid chromatography and the removal of total organic carbon. From cyclic voltammetry, it is observed that for formaldehyde, a small offset of the beginning of the oxygen evolution reaction occurs, but for phenol, the reaction is inhibited and the current density decreases. From the electrochemical degradations, it was determined that 40?mA?cm^?2 is the most efficient current density and the comparison of different supporting electrolytes (Na₂SO₄, NaNO₃, and NaCl) indicated a higher removal of total organic carbon in NaCl medium.     

The impact of earthworms on the abundance of Collembola: improvement of food resources or of habitat?

I assessed the direct influence of earthworm excretions, and the impact of earthworms through their action on the soil structure (increased macroporosity), on the population dynamics of the collembolan species Heteromurus nitidus. The intestinal content of Collembola arising from cultures on different soil types was observed, and two experimental cultures of H. nitidus were run: (1) a culture performed on an inert substrate supplied either with earthworm casts or with soil as food resource, (2) an experiment using microcosms with cores of two humus forms (moder and calcic mull), in the presence or absence of earthworms. The observation of gut contents revealed that H. nitidus feeds on excrements, the composition of which (ratio organic matter/mineral matter) varies according to the humus form where it lived. Slightly aged (10–15 days) organo-mineral casts of earthworms appeared to be a better food than calcic mull aggregates or organic material from moder. Densities of H. nitidus cultured in cores of calcic mull were higher than in moder, except when cores of moder were inhabited by an anecic earthworm for 2 months. The humus form strongly influenced populations of H. nitidus, firstly because densities of predators were higher in moder than in calcic mull, and probably also because of soil macroporosity. It was concluded that earthworms would affect predation on H. nitidus by creating a network of interconnected macropores in which Collembola can move and find shelter.     

Size of Microbial Biomass in Soils of China

The microbial biomass C,N and P of soils all over China were determined in this study to study their affecting factors.The results,about 100-417 mg C kg^-1 soil,18-51 mg Nkg^-1 soil and 4.4-27.3mg P kg^-1 soil,showed the biomass C,N and P in linear relationship with the soil total organic C,toal N and soil organic P.The ratios of C:Nand C:P,ranging from 5.6 to 9.6 and from 11.2 to 48.4 respectively,were affected by soil pH.texture,crop rotation,macroclimate etc.The ratio of C:N in soil biomass increases gradually from the north to the south in China.     

Transformation of Fertilizer-N in Rhizosphere Soils of Wheat

INTRODUCTION There is a close relationship between the transformation of fertilizer-N and the statusof nitrogen nutrition in rhizosphere soils.Previously,Harmsen and Jager(1962)made ananalysis of N and C contents in the rhizosphere soils of upland crops and found thatclose to the root zone there was an enrichment of these substances.     

Fractionation of Zinc in Paddy Soils of China

The rice fields in China amount to 25.4 million hectares of which low yield paddy soils areabout 26％(Xu,1981;Xiao,1981).One of the most important causes of low yield is the defi-ciency in nutrients including zinc.Zinc deficiency usually occurs in calcareous paddy soils withpH>6.5(Zhu and Liu,1981).And the availability of zinc in calcareous paddy soils is lowerthan that in neutral and acid paddy soils.     

Regulation of accumulation of β-subunit of β-conglycinin in soybean seeds by nitrogen

Extract

The storage protein of soybean [Glycine max (L.)] seed mainly consists of glycinin, composed of acidic (38 and 45 kDa) and basic (22 kDa) subunits (Kitamura et al. 1976), and β-conglycinin composed of α′- (75 kDa), α- (72 kDa), and β-(52 kDa) subunits (Thanh and Shibasaki 1978).     

Influence of pre‐storage drying conditions and duration of storage on the effectiveness of root inoculum of Glomus aggregation

A greenhouse experiment was undertaken to evaluate the influence of pre‐storage drying treatments and duration of storage on the effectiveness of root inoculum of Glomus aggregatum. Conditions under which roots were dried prior to storage had little or no effect on the level of arbuscular mycorrhizal (AM) effectiveness measured in terms of pinnule phosphorus (P) content of Leucaena leucocephala leaves after the first 14 days of storage. As duration of storage was further prolonged the time required by root inocula for initiating AM effectiveness and attaining peak levels of effectiveness was progressively prolonged relative to that required by the crude inoculum. However, the two sources of inoculum had similar peak AM effectiveness in many instances. Roots dried in the greenhouse or in the oven at 40°C were significantly inferior to that dried at 60°C. Root inocula stimulated growth of the indicator plant to the same extent as the crude inoculum after 14 days of storage. However, the effectiveness of root inocula in stimulating growth declined with further increase in duration of storage. Among root inocula tested, that dried at 60°C prior to storage was relatively more effective than that dried in the greenhouse or in the oven at 40°C. The overall inferiority of root inocula to that of the crude inoculum appears to be related to loss of viability of root inocula with increase in duration of storage.     

Influence of Salinity in the Bioavailability of Zn in Sediments of the Gulf of Cádiz (Spain)

This study assesses the effect of salinity in bioavailability and toxicity of Zn by means of laboratory bioassays by observing contamination in both sediment and water, accumulation of Zn in biological tissues, and histopathological damage in the gills and guts tissues of Ruditapes philippinarum clams, which were exposed to different types of sediments from the Gulf of Cádiz (SW Spain) as well as two dilutions of toxic mud coming from an accidental mining spill. With this objective, the coefficients of distribution (K _D) for Zn between overlying water and sediments were calculated, the histopathological frequencies in the tissues of the gills and guts of clams were determined, and the biota-sediment bioaccumulation factors as well as the bioaccumulation factors were quantified in the different stations. Results showed that the greatest histopathological damages appeared when the salinity values decreased. Statistical results showed that salinity was inversely correlated with histopathological damage (p?<?0.01) for the lesion index for gills. The most outstanding results were observed in the two dilutions of toxic mud (0.3% and 7.9%) at a salinity value of 10. Salinity was inversely correlated with the concentration of Zn in biological tissues (p?<?0.05) and inversely correlated with the concentration of Zn in water and sediment. Zn mobilization to the overlying water is produced when salinity values decrease.     

γ-HCH-Decomposing ability of several strains of Pseudomonas paucimobilis

Abstract

Extract

We succeeded in isolating a γ-HCH (γ-1,2,3,4,5,6-hexachlorocyclohexane)-decomposing aerobic bacterium from an upland field where γ-HCH had been repeatedly applied for more than 10 years. The bacterium was identified as Pseudomonas paucimobilis (Oyaizu and Komagata, 1983; Senoo and Wada 1989; Wada et al. 1989). We assumed that P. paucimobilis was able to thrive in the upland field by acquiring the γ-HCH-decomposing ability (Tu 1975, 1976) based on the following mechanism:     

Effects of fermented cow‐manure on rooting of mung bean cuttings: The role of nutrients and of abscisic acid

The effects of cabutz, an end product of anaerobic fermentation of cow manure, and the effects of its components, on rooting of cuttings were investigated. Cuttings of mung bean (Vigna radiata L. Wilcz.) plants have rooted better in cabutz than in other rooting media. Cabutz extract increased the number of roots of mung bean cuttings as well as their roots length. Similar effects were obtained with a solution containing only the inorganic constituents of cabutz extracts. The complete cabutz extract, but not its mineral components, caused three pronounced effects: (a) it changed the distribution pattern of adventitious roots along the cuttings; (b) it delayed the initiation of roots at the base of the cuttings in the presence of high concentrations of cabutz extract; and (c) it reduced the water loss by cabutz‐treated cuttings. Similar effects were obtained when external abscisic acid was applied in concentrations similar to what was found in cabutz extracts. It is suggested that the effects of cabutz, on the rooting capability of cuttings, are mostly due to two of its components, nitrate and abscisic acid.     

Zero Point of Charge of Organo—Mineral Complexes

Five soil sapmles collected from China and two soil samples from Pakistan with widely different origin and characterstics were used to study the zero point of charge(ZPC) of soil colloids.The results showed that the value of zero point of charge of H-clay complexes was lower than that of H-clays in all the samples.Natural clay complexes had the highest ZPC as compared to -Hclay complex and H-clay in alfisol,closer to H-clays rather than H-clay complexes in oxisol and udult.The Delta Value of ZPT(zero point of titration )to ZPC was higher in H-Clay complexes than in H-Clays.     

Substances in Urban Snow. A comparison of the contamination of snow in different parts of the city of Luleå, Sweden

The aim of the study was to investigate how the quality of snow varies within a city. The study area is situated in the Luleå municipality, in northern Sweden (lat. 65°35′N and long. 22°10′E). For this study, the city was divided into three different types of areas: housing areas, city centre and outskirts. In one area of each type, sampling sites were selected. Snow samples were taken at nine occasions, once every fourteenth day in the city centre and in the housing area. Analyses were carried out for pH, conductivity, suspended solids and both the total and dissolved concentration of phosphorus and selected metals. It was concluded that traffic or activities related to traffic were a major source of heavy metals and phosphorus in urban snow, both in the city centre and in the housing area. Also, the type of area and the design of the street were important for the quality of snow. A clear relation was found between the pH and the quantity of suspended solids in the snow. Higher pH values were found in snow samples from sites with higher traffic loads, and lower pH values at sites, which were the no-traffic sites, with small quantities of particles. The particulate and dissolved substances in the snow behaved in different ways.     

Effect of Initial Soluble Salt Composition of Saline Soil on Salinity Tolerance of Barley Plant

A pot experiment was carried out on a marine saline soil to study the effect of initial soluble Na/Ca ratio of saline soil on the salinity tolerance of barley plant.The results showed that (1) the Na/Ca ratio affected significantly the dry weight of the plant at an earlier stage of growth,the critical values of initial Na/Ca ratio at which the plant could grow normally on soils containing salts of 2.5,3.5 and 4.5g kg^-1 were 30,20 and 15,respectively;(2)smaller Na/Ca ratio resulted in a considerable decrease in Na accumulation but a great increase in K accumulation in the barley plant;and (3) the plasmallema of barley leaf were badly injured when the Na/Ca ratio was more than 30 and the increase of Na content of plant caused an exudation of K from the leaf cells.Some critical indexes were suggested for the cultivation of barley plant on marine saline soils and could be used as reference in the biological reclamation of marine saline soils.     

Public and Private Employers’ Perceptions of the Competence of Botswana College of Agriculture Graduates

A large sample size technique was used to select 30 employers each from the private and public sector to examine their perception of the competence of agricultural graduates. Data were collected with a structured questionnaire and analyzed using means, standard deviation, and t test. The results show that, for 16 crop production tasks, public agroemployers were favorably disposed to competence in 4 tasks, while private employers were not favorably disposed to competence in any tasks. Both public and private employers were not favorably disposed to competence in farm engineering tasks. The Botswana College of Agriculture curriculum should be overhauled to better prepare graduates for employment.     

Agrophysical assessment of alluvial calcareous soils of the Çumra region of Central Anatolia in Turkey

Some physical (density, coefficient of filtration, particle-size composition, etc.) and chemical (contents of carbonates, organic carbon, nitrogen, etc.) properties of an alluvial calcareous soil were studied in Central Anatolia (Konya province, Çumra region). These heavy-textured (medium clay) soils with a low content of organic carbon (less than 1%) have favorable agrophysical properties due to the stable structure of the pore space. The studies of the water regime of soils under drop irrigation confirm the favorable hydrological properties of these soils. The use of the known agrophysical estimates (after Medvedev, the index of the optimal water regime, etc.) has revealed the high dispersal of the data related to the low humus content in these heavy-textured soils. The favorable structure of the pore space is suggested to be stipulated by the active activity of the numerous and diverse representatives of soil biota. Four phyla predominate in the microbio-logical composition of the soils studied; among them, Actinobacteria is the dominant. The composition of this phylum is dominated by the elevated number of both higher (Streptomyces) and lower (three species of Rhodococcus) actinobacteria. The high biodiversity of bacteria against the background of their great total number and the developed trophic interactions in the microbial community promote the well-balanced production of specific metabolites, including gaseous ones (CO₂, H₂). This circumstance allows this clayey soil to function rather actively while protecting the pore space against compaction and maintaining the optimal density, porosity, and hydrological properties.     

Effects of Water Regime and Reaction of Soil on Properties of Newly—Formed Humic Substances

The effects of soil water regime and soil reaction on nitrogen distribution and fractional composition of newly-formed humus (decayed products) and the structural characteristics of the newly-formed humic acids(HAs) were studied in an incubation experiment,with the following results obtained: 1.The humus newly formed under submerged conditions was higher in the relative content of α-amino acid-N and the humic acid/fulvic acid (HA/FA) ratio than that under upland conditions.The HAs extracted from the former were also higher in C/O ratio,aromaticity and the contents of methoxyl groups and lignin-like components,but lower in the content of carboxyl groups than the HAs from the latter. 2.Under upland conditions,the C/ organic N ratio and the relative content of mobile HA of newly-formed humus were lower,but the HA/FA ratio was higher in the CaCO2-amended treatment than in non-amended treatment.The presence of CaCO3 also resulted in a decrease of C/N ratio of HA and a slight increase of its carboxyl group content.On the other hand,there was no significant change in the composition and properties of the newly-formed humus with the addition of CaCO3 under submerged conditions. 3.Compared with soil HAs,the newly-formed HAs contained more carbohydrates,polypeptides and lignin-like components,and were in lower degrees of oxidation and humification.     

Effect of Mannan-oligosaccharide on Bacterial Community of Piglet after Weaning

来自6窝健康、体重相近的杜长大哺乳仔猪34头随机地分为两组，分别于断奶后饲喂基础日粮或基础日粮＋甘露寡糖(MOS)，收集仔猪断奶当天（实验前）及断奶后7、14、21和28 d粪样，利用PCR/DGGE技术对粪样细菌16S rDNA的V6～V8可变区进行了分析，以研究日粮中添加MOS对断奶仔猪粪样菌群稳定性及多样性的影响。结果表明，断奶前同窝仔猪带谱相似性较高(81%~88%)，但存在个体差异；断奶后同窝仔猪的相似性下降(61%～70%)；断奶后7、14、21和28 d相邻时间段之间，基础日粮组仔猪菌群相似性维持在61%左右，MOS组菌群相似性在断奶第一周下降后，逐渐增加至70%，说明断奶可引起菌群发生变化，而MOS具有使菌群快速稳定的作用。多样性结果显示，断奶7 d后MOS组菌群多样性增加，基础日粮组下降，14 d后两组的差异增加，28 d时基础日粮组多样性为1.52，MOS组为1.38，差异由断奶当天的0.09上升至28 d的1.14，但差异不显著（P >0.05）；条带数分析获得类似结果，即断奶7 d时两组条带数均减少，14 d后MOS组条带数增加，对照组的条带数却减少，实验期内MOS组条带数均高于对照组。 结果提示，断奶导致了菌群的变化，日粮中添加MOS可加速菌群多样和稳定。