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991.
J. Shen Q. Zhao H. Tang F. Zhang Z. Feng T. Okita N. Ogura T. Totsuka 《Water, air, and soil pollution》1995,85(3):1299-1304
During the period from 25 May 1991 to 30 May 1992 the atmospheric concentrations and depositions of oxides of sulfur were continuously measured in a suburban masson pine forest which is currently experiencing severe dieback, in Chongqing, China. The annual mean concentrations of SO2 and particulate SO4 2? were 220 μ g/m3 (77 ppbv) and 32 μ g/m3 respectively. The atmospheric concentrations of these sulfur compounds were high in late autumn and winter. The annual wet and dry depositions of sulfur to the forest as measured by throughfall and stemflow were 93.1 and 46.6 kgSha?1a?1 respectively. These depositions are among the highest level ever reported in the world. Althogh the cause of the dieback of the masson pine trees has not been unequivocally determined, it is probable that the direct impact of SO2 is more likely the cause than acid deposition. 相似文献
992.
Three winter wheat varieties with differing breadmaking quality were grown at two locations in two years at 0 or 3 × 60 kg of nitrogen application. The effect of nitrogen on amount of different components of gluten proteins was determined by reverse-phase HPLC. A high amount of nitrogen led generally to a significant increase of total protein content. However, this increase was obvious only for the gluten proteins; albumins and globulins remained nearly unaffected. The effect of increased protein content on gliadin to glutenin (gli-glu) ratio was inconsistent. While increased protein content increased the gli-glu ratio in the variety Capo, the opposite was true for the variety Renan. Gli-glu ratio of the variety Lindos showed no discernible tendency. As total protein content increased, the ratio of low molecular weight (LMW) to high molecular weight (HMW) glutenins decreased consistently, i.e., in all varieties, in both years and locations. Change of LMW to HMW ratio showed a significant negative correlation to sedimentation value and bread volume. There was no consistent change in the ratio between x- and y-type HMW subunits due to fertilization, as could be shown by densitometric measurements on SDS-PAGE gels. This ratio appeared to be dependent on the genotype and has decreased with decreasing quality. The amount of x-type subunits correlated closely with sedimentation value and bread volume. These results suggest that ratio of HMW glutenins, especially x-type subunits, to total protein content could be the best early detectable parameter with high predictive value for breadmaking quality. 相似文献
993.
994.
T D Doyle J B Proctor 《Journal of the Association of Official Analytical Chemists》1975,58(2):276-282
Potassium guaiacolsulfonate, a highly polar, acidic substance, is readily eluted by chloroform from a pH 4.5 Celite column in the form of its ion-pair with trihexylamine, thereby effecting facile separation from other pharmaceuticals. The sulfonic acid is then back-extracted into aqueous alkali and determined spectrophotometrically. Assay of standard solutions by this procedre averaged 100.44 plus or minus 0.81%. The method was applied successfully to 4 commercial cough preparations containing a variety of other drugs. 相似文献
995.
Changes in all woodlands within study areas in Northamptonshire, Lincolnshire and Cambridgeshire between 1946 and 1972/73 are enumerated using air photographs and ground survey. These conformed to national, long-term trends from coppice to high forest management and from native to introduced species. Differences between areas are ascribed to variation in the relative importance of forestry and agriculture. The effects on wildlife and scientific interest were assessed against criteria developed from an historical approach to woodland conservation, and by examining the area of woodland available to species requiring woodland of particular physiognomy and origin. Modern forestry as an alternative to agriculture has probably favoured species which are good colonisers, catholic in their woodland requirements, and/or require conifers. Species which are poor colonisers and/or require broadleaf woodland have probably declined most in those areas where reforestation has been extensive, and have survived best where forestry has been insignificant in relation to agriculture. Since these are the species most highly valued for conservation and because they are correlated in their occurence with features of special scientific interest, modern forestry is judged to have been relatively harmful to conservation values in Eastern England during the study period. However, the net long-term effects of modern forestry on woodland conservation values are difficult to predict, for this depends partly on the fate of woods in areas devoted mainly to agriculture, which are unlikely to be managed by modern forestry methods. 相似文献
996.
Victor I. Okereke E. Robert Baumann T. Al Austin Donna Schulze Lutz 《Water, air, and soil pollution》1988,37(3-4):325-341
The impact of a flood control, low flow argumentation reservoir in the Midwestern part of the United States on BOD, COD, and ammonia was evaluated in this paper. Fifteen years of weekly water quality data (9 yr before impoundment and 6 yr after impoundment) from four sampling stations upstream and downstream of the reservoir were available for analysis. The annual loading rates of these parameters (kg ha?1 vr?1) were found to correlate well with annual runoff (cm yr?1). Besides, the reservoir was found to have had a significant and beneficial impact on the downstream loading rates of BOD and COD, which were reduced by 55 and 75%, respectively. As for ammonia, the results of this study indicate that its annual loadings at downstream locations were not significantly affected by the reservoir. Average non-point source contributions of BOD and ammonia loadings into the system were found to be about 80 and 55%, respectively. 相似文献
997.
998.
Changes in soil properties and yield response in relation to tillage and residue management treatments in an irrigated groundnut (Arachis hypogea L.)—wheat (Triticum aestivum, L.) rotation on a sandy soil (1972–1974) and on a sandy loam soil (1974–1976) were evaluated. Tillage treatments (T1 and T2) did not cause significant changes in soil properties. Incorporation of crop residues (5 t residue per ha per crop, T3) caused a substantial increase in organic C, available N, and NaHCO3 -extractable P contents in the top 15 cm of both soils. Residue management treatments (T3, T4 and T5) showed no significant effect on soil bulk density and exchangeable K. Crop yields under no-tillage (T1) and conventional tillage (control, T2) were comparable on sandy soil but on the sandy loam soil, no-tillage yielded significantly lower than conventional tillage. Compared with the control, incorporation of crop residues (T3) caused higher yields on sandy soil for groundnut and wheat by 34.1 and 47.4%, respectively, and on sandy loam by 17.1 and 7.2%, respectively. Mulching with crop residues conserved soil moisture and reduced maximum soil temperature (1.5–5.3°C in groundnut and 1.5–2.9°C in wheat) but other measured soil properties were not significantly affected. Significant yield increase due to residue mulching (T4) was observed in sandy soil but it was significantly less than when total crop residue was incorporated (T3). Increased wheat root-weight density in the top 15 cm soil with residue mulching was not reflected in grain yield. Compared with the incorporation of the total amount of crop residue (T3), incorporation of half the amount and application of the other half as mulch (T5) caused lower yields — on sandy soil for groundnut and wheat by 31.5 and 15.7%, respectively, and on sandy loam by 4.8 and 3.6%, respectively. 相似文献
999.
The effects of five agroforestry woody species (Dactyladenia barteri, Gliricidia sepium, Leucaena leucocephala, Senna siamea andTreculia africana) on the surface aasting activity ofHyperiodrilus africanus were studied in an Alfisol (Oxic Paleustalf) in southwestern Nigeria. Casting activity under the woody species decreased in the following order:Dactyladenia sp. (26.4 Mg ha-1 year-1)>Gliricidia sp. (24.4 Mg ha-1 year-1)>Treculia sp. (22.9 Mg ha-1 year-1)>Leucaena sp. (18.6 Mg ha-1 year-1)>Senna sp. (18.3 Mg ha-1 year-1). These differences in casting activity were partly explained by microclimatic effects. Irrespective of the woody species, the worm casts were higher in clay and silt contents, bulk density, water-stable aggregates, pH, organic C, exchangeable cations, effective cation exchange capacity, and extractable P levels than the corresponding surface soils. The woody species did affect the physicochemical properties and P sorption of the worm casts. The content of water-stable aggregates of worm casts decreased in the following order:Dactyladenia sp.>Treculia sp.>Senna sp.>Leucaena sp.>Gliricidia sp. Large differences in extractable P levels were observed.Senna sp. was associated with the highest extractable P level (11.5 mg kg-1) andTreculia sp. the lowest (4.9 mg kg-1). P sorption was highest on worm casts underDactyladenia sp. and lowest on those underTreculia sp. Without fertilizer application, there were no significant differences in the dry weight of maize grown in the different worm casts. With NPK applications, the dry weight of maize grown in worm casts associated withTreculia sp. was significantly lower than that of maize grown in the other worm casts, mainly due to the low extractable P level. Despite a high organic C and exchangeable K status, maize grown in the worm casts still responded significantly to N and K applications. The N uptake by maize grown in worm casts associated withTreculia sp. was lower than that in the other treatments. 相似文献
1000.
The influence of sewage sludge on microbial activity in soil The effect of untreated, pasteurized and irradiated sewage sludge on soil biology was studied in model and field experiments. Sewage sludge from the sewage plant Geiselbullach in the west of Munich city was used for these experiments. The investigations were performed with 4 soil types according to the different locations. All the results demonstrate that there is an increase in biomass after application of sewage sludge while there were definite influences from the location. No significant relation could be observed according to sewage sludge treatment. Under favourable lab conditions the mineralization of the organic matter applied to the soil with higher amounts of sewage sludge induces in short time a definite decrease in pH. In accordance with these changes in pH there is a corresponding decrease in microbial biomass. Early results on the influence of microbial N-cycle demonstrated that amounts of sewage sludge applied under practical conditions brought an increase in denitrification capacity of the soil. In the experiment with soils nitrification rate was doubled after sewage sludge application. 相似文献