Development of Heterotrophic and Ammonifying Bacterial Populations as Affected by the Fish Clarias batrachus (Linn.) under Different Experimental Conditions

Fishes of the carnivorous species Clarias batrachus of different size (length of 12 to 22 cm, weight of 15 … 57 g) were kept in aquaria with and without feeding on fish meal with or without an addition of rice bran, the fish mass having been 15 g/l. Aquaria with the same addition of food pellets were used as the control. The number of colonies of heterotrophic bacteria as well as the M.P.N. of the ammonifying bacteria was higher in the fish-containing aquaria than in the control, and in the fish-containing aquaria the colony number and the number of ammonifying bacteria significantly increased with the size of fishes and with feeding. The heterotrophic bacteria reached the highest numbers 4 h after the beginning, the numbers of ammonifyers increased till the fifth day. Parallel to the number of ammonifyers, also the ammonium concentration increased.     

The Influence of a Teleost Clarias batrachus (L.) on the Behaviour of Different Species of Nitrogen in Water

Different experimental conditions (fed large, fed small, starved large, starved small groups, batch offered ration during experiment and low fish loading for a constant volume of water) of the carnivorous fish Clarias batrachus resulted in marked changes in the concentration of different N species (ammonium-N, nitrate-N, nitrate-N, organic-N as well as the sum of all forms of N) in aquaria water. Organic forms of nitrogen were the most important species of nitrogen excreted by the test fish. The maintenance nitrogen excretion rate was distinctly higher in larger fishes than in smaller ones. Different species of N were found to differ significantly depending upon the fed or starved conditions as well as small or large groups. A reduced level of oxygen in experimental aquaria inhibited the synthesis of nitrate which was maximum in control aquaria with considerably higher values of oxygen.     

Short Term Effects of Aldrin and Swascofix CD-38 on the Feeding and Respiratory Behaviours of Clarias batrachus and Cirrhina mrigala

Fish were kept in non-toxic water or at 0.5, 0.25 and 0.125 of the LC_50,96h of the ten-side or insecticide for 24 h and fed with toxified and non-toxified feed. Toxified feed in normal water resulted in a maximum feed intake, while normal feed in toxified water resulted in a minimum one. In each case, the feed intake was lower compared with the control, and the feed intake was inversely proportional to the toxicant concentration. In a simple respirometer the oxygen consumption in mg · kg^?1 · h^?1 was tested for 1, 2, 4, 6, 8, 10, 12, 24, 36, 48, 60, 72, 84 and 96 h of exposure to 1.5, 1.0 and 0.5 of the LC_50,96h of both substances. It was a flow device which was closed only for measurement for one hour. 1.5 LC₅₀ Aldrin causes a continuous reduction of respiration until death. The same effect occurred with Cl. batrachus for 1.5 LC₅₀ of the tenside, whereas with C. mrigala death was caused by a pronounced increase of respiration. In all other cases, after a phase of sensitization for 4 … 8 h respiration increased considerably to more than 300% of the control, which was followed after 12 … 24 h by acclimatization to normal respiration values.     

Physicochemical Properties of Bottom Sediments in Water Bodies in the Central and Southern Vietnam

Water Resources - The physicochemical characteristics of bottom sediments in inland water bodies in the Central and Southern Vietnam are presented for the first time, including particle-size...     

Capability of Pentavalent Arsenic Bioaccumulation and Biovolatilization of Three Fungal Strains under Laboratory Conditions

In order to control and remediate arsenic (As) contaminated soil, sediment or water, fungi are used to investigate their potential accumulation and volatilization of As. In this study, after cultivation for 2 days, the dry weights of mycelia for Trichoderma asperellum, Fusarium oxysporum and Penicillium janthinellum all show an increased trend when the As(V) concentration ranges from 0–50, 0–50, 0–80 mg/L, respectively. When the culture system is loaded with 2500 μg As(V), which represents 50 mg/L As, and cultivated for 5 days, P. janthinellum presents the highest efficiency of 87.0 μg/g for As bioaccumulation, and the order of the efficiency for As bioaccumulation is P. janthinellum > T. asperellum > F. oxysporum. However, the order of the amount of volatilized As is F. oxysporum > P. janthinellum > T. asperellum, and the highest amount of volatilized As is observed for F. oxysporum at 181.0 μg. Thus, the ability of As bioaccumulation and biovolatilization for T. asperellum and P. janthinellum is reported for the first time in this study.     

Changes in the Level of Proteins,Free Amino Acids and Protease Activities of Clarias batrachus in Response to Sodium meta‐arsenite Intoxication

Increased hazard of arsenic toxicity at many provinces of India causing extensive contamination of their wetlands. To illustrate the consequences of the arsenic menace on the aquatic fauna, a nutritionally important freshwater catfish Clarias batrachus (Linn.) was subjected to the stress of sublethal concentration (1 mg/L; 5% of 96‐h LC₅₀ value) of sodium meta‐arsenite. The alterations induced by the arsenic salt on certain biomolecules (proteins, free amino acids (FAA), and protease activities) in five tissue components (muscle, liver, brain skin, and gills) of the fish using biochemical techniques were estimated. Significant (p < 0.01) decrease in the concentration of proteins in all the tissues (19.74–44.84% in muscles; 3.17–49.39% in liver; 10.05–36.16% in brain; 12.62–52.01% in skin and 7.34–61.69% in gills), and significant (p < 0.01) increase in FAA (6.84–269.89% in muscles; 125.89–358.03% in liver; 1.07–152.90% in brain; 29.31–401.62% in skin and 38.53–165.07% in gills), and protease activities (43.59–183.33% in muscles; 19.52–131.90% in liver; 8.85–46.72% in brain; 33.33–261.53% in skin and 25.39–50.79% in gills) of the exposed fish were observed. This increase in amino acids and enzyme activity point out toward breakdown of protein leading to their depletion.     

Phenol Accumulation in the Larvae of the Species Agrion puella L.(Insecta,Odonata) under Laboratory Conditions

In an aerated batch experiment for one to six days the phenol accumulation is investigated in the surviving and killed larvae of Agrion puella at phenol concentrations of 50 to 200 mg/l in the medium. The rate of mortality increases with the initial concentration of phenol, although about 40% phenol is microbially digested during the test. The phenol accumulation in μg/g wet substance is always higher in the surviving individuals than in the killed ones, but it shows an identical time trend for both. On the first day, accumulation is high, and till the third day it decreases. On the fourth day, it reaches a maximum, and then it drops sharply to its minimum on the sixth day. The measured actual accumulation is the result of changing intake and elimination rates, especially the elimination rates decreasing with increasing duration of tests and test concentration due to metabolic disturbances. The absolute minimum on the sixth day is determined also by the reduced phenol concentration. The limit of accumulation for a chronic poisoning can be estimated at 70 μg/g phenol.     

Protein Digestibility by Khosti Fish Colisa fasciatus (Pisces,Anabantidae) under the Influence of Certain Factors

Protein digestibility was determined via two feeding trials in glass aquaria by the indicator (Chromium oxide) method using a mixture of shrimp powder with oil cake and wheat bran respectively (1: 1 W/W) as food. Analyses of feed were made to calculate the crude protein, carbohydrate, lipid and ash contents. Feces were analysed to determine their total nitrogen and chromium oxide. Protein digestibility was studied in relation to salinity of the medium size and weight of the fish body. The apparent digestibility of crude protein of a corresponding die has shown that 1st: Younger fish do possess a lower capability of protein digestion than fish having a medium weight and medium size; 2nd: Older fish with a high weight and large size exhibit no improvement in efficiency to digest the food protein, though their weight and size are significantly greater than those of middle weight and medium size fish; 3rd: The replacement of oil cake by wheat bran decreases the protein digestibility of shrimp powder mixture with them; 4th: A salinity (NaCl) of the aquatic medium at or above 3 g/l depletes the protein digestibility when fish of the same size were experimented with; but a salinity up to 2 g/l does not result in a significant decrease in the protein digestion rate.     

单、双向动三轴试验条件下饱和砂动力特性对比

在饱和砂土地震液化评估中,多用单向动三轴试验代替双向动三轴试验获得土体的抗液化强度。由于单向激振和双向激振产生的应力路径不同,土的动力特性受应力路径影响,其合理性尚待证明。本文利用双向振动三轴仪分别采用单、双向振动形式进行饱和砂土振动液化试验,对比了相同动剪应力作用下累积孔压和动强度,分析了较大循环振次作用下单、双向振动方式使试样动力响应产生差异的原因,提出了利用单向三轴试验代替双向振动模拟地震循环剪应力获得砂土动力特性的室内试验方法的适用条件。     

Effects of Hydrogel Amendment to Different Soils on Plant Available Water and Survival of Trees under Drought Conditions

The effect of super absorbent polyacrylate (SAP) hydrogel amendment to different soil types on plant available water (PAW), evapotranspiration and survival of Eucalyptus grandis, Eucalyptus citriodora, Pinus caribaea, Araucaria cunninghamii, Melia volkensii, Grevillea robusta, Azadirachta indica, Maesopsis eminii and Terminalia superba was investigated. The seedlings were potted in 3 kg size polythene bags filled with sand, loam, silt loam, sandy loam and clay soils, amended at 0 (control), 0.2 and 0.4% w/w hydrogel. The tree seedlings were allowed to grow normally with routine uniform watering in a glass house set up for a period of eight weeks, after which they were subjected to drought conditions by not watering any further. The 0.4% hydrogel amendment significantly (p < 0.05) increased the PAW by a factor of about three in sand, two fold in silt loam and one fold in sandy loam, loam and clay soils compared to the control. Similarly, the addition of either 0.2 or 0.4% hydrogel to the five soil types resulted in prolonged tree survival compared to the controls. Araucaria cunninghammi survived longest at 153 days, while Maesopsis eminii survived least (95 days) in sand amended at 0.4% after subjection to desiccation. Evapotranspiration was reduced in eight of the nine tree species grown in sandy loam, loam, silt loam and clay soils amended at 0.4% hydrogel. It is probable that soil amendment with SAP decreased the hydraulic soil conductivity that might reduce plant transpiration and soil evaporation.     

大气作用下膨胀土地基的水分迁移与胀缩变形分析

运用土体渗流和蒸发理论,建立了大气-非饱和土相互作用模型;以现场观测的气象数据作为边界条件,进行了地基土中水分迁移的数值模拟,得到了大气作用下地基土体含水量的动态分布规律。计算结果表明,地基土中含水量变化幅度随深度增加而递减,3.5 m深度以下土体的体积含水量基本不变,从而确定了南宁地区膨胀土地基的大气影响层深度为3.5 m。在此基础上,结合已有膨胀土胀缩性指标的干湿循环效应研究成果,提出了一种同时考虑干湿循环效应和1.0 m深处含水量变化的膨胀土地基胀缩变形计算方法,通过算例将该法与传统方法进行比较,结果显示该法更加符合工程实际。     

Influence of Supergranulation on the Properties of Sunspot Bipoles

Geomagnetism and Aeronomy - The properties of solar bipoles based on data from magnetic field observations at Mount Wilson Observatory during the period of 1917–2016 are considered. Special...     

Assessment of Water Quality in the Elbe River at Low Water Conditions Based on Factor Analysis

An assessment of water quality measurements during a long‐lasting low water period in the Elbe River is presented. Weekly samples were taken from May to December 2003 at a sampling site in the middle part of the Elbe River. For multivariate data analysis, 34 parameters of 46 samplings were considered. As a result of this analysis, 78% of the variance of the data set is explained by five factors. They can be assigned to the following latent variables: season (37.5%) > tributaries (12.7%) > re‐suspension (10.4%) > discharge (9.4%) > complexation (8.5%). For the investigated sampling site, two key processes were identified as dominating factors on the water quality during low water conditions. First, seasonal phytoplankton development caused changes in redox conditions with consequences for re‐solution of pollutants from sediments. Second, tributaries have a higher impact on the main stream, due to changes in mixing processes. Therefore, in addition to flood investigations, monitoring strategies, and management plans should be developed in order to survey changes in water quality during low water conditions.     

Marker Indices for Assessing the Conditions of Water Bodies under Moderate Anthropogenic Impact: Case Study of the Pra River

A system of marker-based estimates of the environmental conditions of water bodies in the Pra River basin is proposed based on the results of field studies and archive data. Correlation equation were derived for relating the selected markers with other indices.     

Monitoring Hydrogeologlcal Conditions in Fractured Rock at the Site of Canada's Underground Research Laboratory

Atomic Energy of Canada Limited is constructing an Underground Research Laboratory (URL) at a depth of 250m in a plutonic rock body near Lac du Bonnet, Manitoba. The facility is being constructed to carry out a variety of in situ geotechnical experiments as part of the Canadian Nuclear Fuel Waste Management Program. A unique feature of the URL, in comparison to other similar facilities such as the Stripa Mine in Sweden, is that it is to be constructed below the ground water table in a previously undisturbed plutonic rock body. One of the main research objectives of the project is to develop and validate comprehensive three-dimensional models of the hydrogeology of the rock mass encompassing the URL site. These models will be used, before excavation of the URL shaft begins, to predict the hydrogeological perturbation that will be created by the excavation of the shaft and the horizontal working levels below the ground water table. As a model-validation exercise, these drawdown predictions will be compared with actual hydrogeological perturbations that will be monitored at the study area over the next several years by an extensive network of instrumented boreholes. Measurements made in an array of boreholes extending to depths of 1,000m on the 4.8 km² study area have established that the permeability distribution in three major extensive subhorizontal fracture zones controls the movement of ground water within the rock mass. Several types of multiple-interval completion systems have been installed in the boreholes to monitor the three-dimensional, physico-chemical hydrogeological conditions within the fractured rock mass. These include conventional piezometer nests and water-table wells that have been installed in shallow holes (less than 30m deep), and multiple-packer/ multiple-standpipe piezometers and multiple-interval casing systems installed in deeper holes (30 to 1,000m deep). An automated, electronic, piezometric pressure-monitoring system has been designed to collect continuous measurements from 75 isolated hydrogeological monitoring positions within the rock mass. Another 200 positions are being monitored frequently using a variety of techniques. Piezometric data have been collected from this monitoring network to establish baseline conditions prior to any excavation into the rock mass. These data have also been used to determine the steady-state, three-dimensional ground water flow regimes that exist at the URL site under natural conditions.