Soil and vegetation changes in experimental birch plots on a Calluna podzol

A long-term experiment set up by G. W. Dimbleby to test the effect of birch as a soil improver on a heather moor podzol is described. After 30 yr, an acid woodland type of vegetation developed under the birch trees with Deschampsia flexuosa and Vaccinium myrtillus locally dominant. The mean annual dry matter production of stems and branches was approximately 2.9 t ha^?1. The raw humus layer removed as an experimental treatment had re-formed. Its pH, about 3.4, had remained unchanged for 15 yr. The mean extractable Ca content of the upper 3 cm horizon of the birch plots and of the control plots under heather had increased and on some of the birch plots the concentrations of exchangeable Ca were somewhat higher than those under heather. The N content of the Ol + Of, Oh and Ea horizons was higher under the birch than under heather but there was no evidence of movement of Fe out of the ironpan under the influence of birch. The profile under birch remained a fully differentiated podzol.     

Toxicity and efficacy of Furanace on channel catfish Ictalurus punctatm (Rafinesque) infected experimentally with Aeromonas hydrophila

Abstract. The 96-h medium tolerance limit of Furanace (nifurpirinol: P-7138) for channel catfish Ictalurus punctatus at 21°C was 0-94 mg/1. The most effective treatment level for channel catfish, experimentally infected with Aeromonas hydrophila , was 2mg/1 for 6.5 h. Furanace at 0.5 and 1.0 mg/1 in brain heart infusion agar reduced in vitro growth of A. hydrophila and at 2.0 mg/1 growth was completely     

Gas-liquid chromatographic determination of monosodium glutamate in soups and soup bases.

A method is given for determining monosodium glutamate (MSG) in soups and soup bases by gas-liquid chromatography (GLC) of the trimethylsilyl ether derivative of glutamic acid. This method compared favorably with existing methods including GLC of the trifluoroacetate (TFA)/butyl ester derivative, and analysis on an amino acid analyzer. In addition, some samples were analyzed by GLC/mass spectrometry. The MSG content of various products ranged from approximately 0.2% in some condensed soups to 13.1% on bouillon cubes. The method, which can detect as little as 0.05%, requires only a 10 min single step derivatization at room temperature and is preferred to the TFA/butyl ester technique.     

DC polarography of cephradine and its application to capsules.

A polarographic method has been developed for the quantitative analysis of cephradine and its dosage forms. Direct determinations on capsules are carried out; excipients and coloring matter do not interfere in the determination. The electroactive product is formed by acidic hydrolysis with 5.0N HCl and heating at 80 degrees C for 60 min. Two polarographic waves are obtained: I = -0.46 V and II = -0.78 v vs. SCE. Both reduction waves are diffusion controlled. Wave I is preferred for analytical purposes. The precise chemical identity of the electroactive product has not been determined, but UV spectral data and the TLC Rf value are reported. A linear relation is established for levels of cephradine between 10(-2) and 10(-5)M in 5.0N HCl.     

A method for measuring adenosine triphosphate in soil

A method was devised for the extraction and measurement of adenosine 5'-triphosphate (ATP) in soil that minimizes sorption of ATP on the soil colloids. Soil was ultrasonified for 1 min with a solution containing trichloracetic acid (0.5 m). disodium hydrogen orthophosphate (0.25 m) and paraquat dichloride (0.1 m). The ATP content of the filtered extract was determined without further treatment in a scintillation spectrometer by the firefly luciferin-luciferase system. Recovery of added ATP was greater using the extratant containing trichloracetic acid, orthophosphate and paraquat than with trichloracetic acid alone or with a sulphuric acid extradant. Recoveries of added ATP ranged from 45% to 84% in thirteen different soils; ATP contents from 0.64 to 9.03 μg g^?1 soil.     

Cycling of nitrogen by surface-casting earthworms in a pasture ecosystem

Production of surface casts and the removal of plant litter from the soil surface by earth-worms had similar seasonal variations, with maximum values in May and minimum values occurring in July and August. Seasonal variations in the total nitrogen (TN) and oxidizable carbon contents of casts were closely related to variations in litter production. The C:N ratio of casts (10.7) was consistently smaller than that of underlying soil material (15.0 and 14.2 for the 0–5 and 18–22 cm depths, respectively), which is probably due to the mineralization of plant-derived organic material during passage through earthworms and utilization of low C:N ratio litter. Seasonal changes in the amounts of inorganic N forms in casts showed a build-up of NH₄⁺N in the cooler winter months (July and August), attaining a maximum of 112 μg.g^?1. with a decrease in autumn (April and May) and early spring (September and October), reaching a minimum of 54 μg.g^?1. The opposite trend existed for seasonal variations in the NO₃^?-N content of the casts. Because only minor fluctuations in the amounts of N forms were obtained for underlying soil material during the casting period, the more dramatic changes observed in the casts could not be explained by soil variations. Seasonal variations in urease enzyme activity, associated with fluctuations in organic matter content, were more important than the effect of temperature on enzyme activity in accounting for seasonal variations in the NH₄⁺-N content of casts. It was calculated that 73% of the TN content of litter removed from the surface by earthworms was accumulated in casts, indicating both the importance of earthworms in incorporating litter N with soil material and the inefficiency of N digestion by earthworms.     

Biodegradation of litter in Eucalyptus pauciflora communities—II. Fungal succession in fungicide- and insecticide-treated leaves

Fungal succession on untreated and fungicide- and insecticide-treated leaves of Eucalyptus pauciflora was compared. Natural succession on untreated leaves fits the general scheme for succession on deciduous tree leaves. Initial colonizers are species of Coelomycetes and Moniliales. When the numbers of Coelomycetes decrease in the late stages of decomposition, the frequency of Penicillium species and species of Zygomycetes increases. The succession is affected only marginally by DDT and dieldrin treatment while benomyl severely restricts the occurrence of most fungal species. The effect of benomyl persists even after exposure for 48 weeks in the field.     

Nitrous oxide emission from soils at low moisture contents

The production of nitrous oxide by soils was studied over short periods at a range of moisture contents up to field capacity with a highly-sensitive gas Chromatographic method.Nitrous oxide (N₂O) was emitted from all soils studied at all soil moisture contents, which ranged from air dry to field capacity. The rate of emission increased with increasing moisture content and with increasing temperature up to 37°C.The evolution of N₂O was not due to displacement of soil air during wetting. It was inhibited by HgCl₂ and toluene, and was prevented by formaldehyde and autoclaving. Thus it appeared to be due to microbiological processes.The results of experiments with nitrification and denitrification inhibitors suggest that a considerable part of the N₂O was produced by the oxidation of ammonia. Production by denitrification of nitrate cannot be ruled out. The relative importance of these two mechanisms probably depends on the moisture and oxygen content of the soil.It is concluded that the microbial production of N₂O is continuous in soil at all moisture contents. The process at low moisture contents constitutes an important component in the cycle which maintains the N₂O concentration in the atmosphere.     

Hepatomas in Atlantic tomcod Microgadus tomcod (Walbaum) collected in the Hudson River estuary in New York

Abstract. Incidental observations of Atlantic tomcod during routine laboratory processing revealed that a portion of the adult population collected during the 1977–78 spawning season had enlarged livers containing dark coloured tumours and other abnormalities. Of the total of 264 livers collected between 16 January and 27 February 1978 and grossly examined for prevalence of abnormalities, 25% appeared to contain neoplastic nodules and hepatocellular carcinoma. One liver contained a massive tumour (7 × 12 mm) that involved approximately 60% of the liver. The exact causes of the high prevalence of hepatocellular carcinoma are unknown but poly-chlorinated biphenyls (PCBs) are suspected of having a possible role. The Hudson River is known to contain elevated concentrations of PCBs. Twelve tomcod livers from the 1977–78 spawning population representing both normal and hepatoma conditions contained concentrations of PCBs ranging from 10–9 to 98–2 ppm (mean of 37–5 ppm).     

Photoperiod induced off-season spawning of pink salmon (Oncorhynchus gorbuscha)

Four groups of pink salmon, which had been reared under artificial light, became sexually mature and produced viable gametes: 59 days prior to, and 19 – 32 days, 115 days and 220 days after their expected date of reaching sexual maturity. Altered times of sexual maturation were obtained by accelerating, leaving unchanged, or decelerating the rate of change of photoperiod which each group of fish would normally receive during its first year of life. All groups of fish were exposed to a normal rate of change in photoperiod during their final year of life. Mean fecundity was reduced from the 800–2000 ova observed in wild stocks, and ranged from 629 for the 59 day advanced fish, to 862 for the 115 day delayed fish. Egg mortality during the period from fertilization to eyeing was much greater in the three groups of fish subjected to accelerated or decelerated rates of change in photoperiod than in the fish subjected to the normal rate of change in photoperiod. Some of the progeny of the 220 day delayed fish, which were reared under artificial light with the normal rate of change in photoperiod set 220 days out-of-phase, became sexually mature 2 years after they had begun life as fertilized eggs.