Trace metal content of the forest floor in the green mountains of Vermont: Spatial and temporal patterns     

Andrew J. Friedland  Arthur H. Johnson  Thomas G. Siccama 《Water, air, and soil pollution》1984,21(1-4):161-170

The organic horizons of forest soils in eleven stands along an elevational gradient on Camels Hump Mountain, Vermont, were analyzed for Pb, Cu, Zn, Ni, Cd, organic matter and organic C. Lead concentration and amount increased with elevation. Vertical profiles of forest floor in the boreal forest showed that highest concentrations for most metals occurred in the upper F horizon. Comparison with 1966 and 1977 samples from the same stands showed that concentrations of Pb, Cu, and Zn and percent organic matter increased by as much as 148% in the intervening 14 yr. Estimates of 1966 amounts of Pb, Cu, and Zn indicated that increases in trace metal amounts over the 14 yr period are consistent with annual deposition rates reported in the literature.  相似文献   

Nutritional value of a highly digestible sorghum cultivar for meat-type chickens     

Elkin RG  Arthur E  Hamaker BR  Axtell JD  Douglas MW  Parsons CM 《Journal of agricultural and food chemistry》2002,50(14):4146-4150

The nutritional value of a newly discovered sorghum mutant cultivar (P851171), with high in vitro protein digestibility, was compared to those of corn and two normal sorghums (P721N and 611Y) in two chick feeding trials. Although 8-20 day protein efficiency ratios and net protein ratios of all three sorghums were inferior to those of corn, P851171 and 611Y had markedly greater mean true amino acid digestibilities (TAAD) than either corn or P721N. In a subsequent 42-day experiment, all three sorghums supported weight gains equal to those of the corn-fed chicks. Feeding suboptimal levels of dietary protein resulted in reduced weight gains and no observed benefits of P851171 or 611Y. Furthermore, chicks fed P851171 exhibited poorer feed/gain values as compared to those fed the other cereals. It is possible that the starch content/carbohydrate profile of P851171 was inferior to that of the other sorghums, which offset its superior TAAD and resulted in poorer broiler performance.  相似文献   

Organic amendments to enhance herbicide biodegradation in contaminated soils   总被引：2，自引：0，他引：2  

Thomas B. Moorman  Jennifer K. Cowan  Ellen L. Arthur  Joel R. Coats 《Biology and Fertility of Soils》2001,33(6):541-545

Pesticide contamination of soil and groundwater at agricultural chemical distribution sites is a widespread problem in the USA. Alternatives to land-farming or solid waste disposal include biostimulation and phytoremediation. This research investigated the ability of compost, corn stalks, corn fermentation byproduct, peat, manure, and sawdust at rates of 0.5% and 5% (w/w) to stimulate biodegradation of atrazine [6-chloro-N-ethyl-N'-(1-methyethyl)-1,3,5-triazine-2,4-diamine], metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide], and trifluralin [2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine] added as a mixture to soil. Initial concentrations were 175ᆾ mg atrazine kg^-1 soil, 182ᆭ mg metolachlor kg^-1 soil, and 165ᆫ mg trifluralin kg^-1 soil. After amendment addition, 30% of the atrazine, 33% of the metolachlor, and 44% of the trifluralin was degraded over 245 days, which included 63 days' aging prior to amendment additions. Atrazine degradation was enhanced by 0.5% manure, 5% peat, and 5% cornstalk amendments compared to nonamended soils. Metolachlor degradation was enhanced by all amendments at the 5% level, except for compost and peat. Amendments had no effect on trifluralin degradation. The 5% addition of compost, manure, and cornstalks resulted in significant increases in bacterial populations and dehydrogenase activity. A second experiment compared the persistence of atrazine, metolachlor, and trifluralin applied in a mixture to their persistence in soil individually. A combined average of 123 mg atrazine kg^-1 remained in soil treated with the three-herbicide mixture compared to 31 mg atrazine kg^-1 remaining in soil treated with atrazine only. Atrazine mineralization and atrazine-degrading microorganisms were suppressed by high concentrations of metolachlor, but not by trifluralin.  相似文献   

Zinc Cu,Ni and Cd in the forest floor in the Northeastern United States     

Andrew J. Friedland  Arthur H. Johnson  Thomas G. Siccama 《Water, air, and soil pollution》1986,29(3):233-243

A regional study was conducted to assess current levels of trace metals in the forest floor, and to establish a baseline for future studies of metal accumulation. Quantitative forest floor samples collected from 78 sites in 9 states in the northeastern United States in 1978 and 1980 were analyzed for Zn, Cu, Ni, and Cd. Mean amounts present in the forest floor were 9.8 ± 1.9 (standard error of the mean), 1.7 ± 0.2, 0.86 ± 0.08, and 0.13 ± 0.01 kg ha^?1, for Zn, Cu, Ni, and Cd, respectively. Mean concentrations were 133 ± 25, 19.5 ± 1.6, 11 ± 0.8, and 1.7 ± 0.1 mg kg^?1, respectively. Differences in metal and organic matter concentrations and amounts among forest types were attributed to geographic location of specific forest types rather than to direct biotic influence. No element was strongly correlated with elevation for the entire sample area. Regional patterns of elemental amounts showed that trace metal levels are slightly higher in the southern part than in the northern part of the study region. Regional variation of Zn, Cu, Ni, and Cd in the forest floor was not indicative of atmospheric deposition except near point sources of pollution.  相似文献   

Microparticle dispensers for the controlled release of insect pheromones     

Stipanovic AJ  Hennessy PJ  Webster FX  Takahashi Y 《Journal of agricultural and food chemistry》2004,52(8):2301-2308

The potential utility of micrometer-sized particles as controlled-release devices for the volatilization of insect pheromones for mating disruption applications is evaluated in this study for two pheromone/model compound systems (codlemone/1-dodecanol and disparlure/1,2-epoxyoctadecane). To expedite the measurement of release rates from these particle devices, two techniques based on thermogravimetric analysis (TGA) have been exploited: isothermal TGA (I-TGA) at elevated temperatures (40-80 degrees C) with N(2) convection and volatilization temperature (VT) by dynamic TGA. A correlation between these two methods has been established. Samples that exhibit a higher VT provide a lower release rate from a particle substrate. Using these techniques, it has been demonstrated that chemical interactions between adsorbed liquids and particle surfaces may play a small role in defining release characteristics under conditions of low surface area, whereas parameters associated with total surface area and micropore structure appear to be much more significant in retarding evaporation for uncoated particles containing an adsorbed liquid. Additional regulation of release rates was achieved by coating the particle systems with water-soluble or water-dispersible polymers. By careful selection of particle porosity and coating composition, it is envisioned that the evaporation rate of pheromones can be tailored to specific insect control applications.  相似文献   

Otoacoustic emission in a dog     

M H Sims  J J Brace  D A Arthur  R C Harvey 《Journal of the American Veterinary Medical Association》1991,198(6):1017-1018

A 7-month-old female Poodle was evaluated for a sound continuously emanating from its left ear. The frequency and intensity of the tone was matched by use of a multifrequency audiometer. The frequency and intensity of the sound were 9,594 Hz and 45.5 decibels sound pressure level, respectively. On the bases of normal brain stem auditory-evoked responses and behavioral response to sound, the dog was believed to have normal hearing in both ears. Emission of sound from an ear, referred to as an otoacoustic emission, is a condition that has been reported in human beings and small animals. Successful treatment in human patients with drugs and masking sounds is difficult, and treatment has not been reported in animals. This condition in dogs is not considered life-threatening.  相似文献   

The effects of selenium, housing and management on the incidence of pneumonia in housed calves   总被引：2，自引：0，他引：2  

M Phillippo  J R Arthur  J Price  G J Halliday 《The Veterinary record》1987,121(22):509-512

The occurrence and incidence of pneumonia in housed calves were not related to the selenium status of the herd as measured by blood glutathione peroxidase activity nor were they affected by selenium treatment of calves during the neonatal period. Pneumonia was related more closely to herd size and building design.  相似文献   

Maedi-visna virus infection in commercial flocks of indigenous sheep in Britain     

G C Pritchard  J B Spence  M J Arthur  M Dawson 《The Veterinary record》1984,115(17):427-429

The recent identification of maedi-visna virus infection in three commercial flocks of indigenous sheep in Britain is described. In one flock the evidence suggested that overt clinical disease was present. The implications of the findings are discussed.  相似文献   

Alkyl aryl ketone oxime O-ethers: A novel group of pyrethroids     

Michael J. Bull  J. Hugh Davies  Robert J. G. Searle  Arthur C. Henry 《Pest management science》1980,11(2):249-256

The alkyl phenyl ketone oxime O-benzyl ethers are a new group of insecticidal compounds. Although they lack the ester linkage, they resemble the pyrethroids in general, and the esters of 2-phenylalkanoic acids, in particular fenvalerate, because they show similar physiological effects on isolated nerve preparations and on whole insects; they also show a similar pattern of change of biological activity in response to structural change. The compounds may exist as two geometric isomers, of which only the (E) series shows significant biological activity; this observation appears to have some bearing on the relationship between conformation and activity in the pyrethroid series as a whole.  相似文献   

Lower respiratory disease in thoroughbred racehorses     

Rick M. Arthur D. V.M. 《Journal of Equine Veterinary Science》1989,9(5)

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