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Mark C. Roberts 《Resources Policy》1988,14(4)
This paper explores the general reasons for the sudden decline in the growth of world metal demand which began after 1974 and continues to impact the metal industries. For all of the eight metals studied, except aluminium, the dominant cause of this atrophy in demand is the stagnation in total world economic growth, which has caused reduced demand for all goods and services. In addition, consumer preferences have shifted away from metal-intensive goods, further reducing the need for metals. However, materials substitutions and manufacturing technologies have continued to evolve towards lower use of metal in each product at much the same rate after 1974 as before. Therefore, these aspects do not explain the sudden shortfall after 1974 except in the case of aluminium which experienced a dramatic change during the energy crisis years. 相似文献
35.
Bending GD Lincoln SD Edmondson RN 《Environmental pollution (Barking, Essex : 1987)》2006,139(2):279-287
The extent of within field variability in the degradation rate of the pesticides isoproturon, azoxystrobin and diflufenican, and the role of intrinsic soil factors and technical errors in contributing to the variability, was investigated in sites on sandy-loam and clay-loam. At each site, 40 topsoil samples were taken from a 160 x 60 m area, and pesticides applied in the laboratory. Time to 25% dissipation (DT25) ranged between 13 and 61 weeks for diflufenican, 5.6 and 17.2 weeks for azoxystrobin, and 0.3 and 12.5 weeks for isoproturon. Variability in DT25 was higher in the sandy-loam in which there was also greatest variability in soil chemical and microbial properties. Technical error associated with pesticide extraction, analysis and lack of model fit during derivation of DT25 accounted for between 5.3 and 25.8% of the variability for isoproturon and azoxystrobin, but could account for almost all the variability for diflufenican. Azoxystrobin DT25, sorption and pH were significantly correlated. 相似文献
36.
D. Roberts 《Marine Biology》1972,16(2):119-125
The rate of uptake of Endosulfan by Mytilus edulis L. exposed to pesticide concentrations of 0.1, 0.5, and 1.0 mg/l, and its subsequent elution on removal to clean sea water, was investigated. Higher residue levels were recorded for mussels exposed to higher concentrations of the pesticide, but concentration factors were reduced. There was a rapid initial fall in tissue residue levels on transfer to clean sea water due, it is suggested, to elution of Endosulfan adsorbed on particulate matter assimilated in the gut. The spawning period was prolonged at higher concentrations and, at 1.0 mg/l, the onset of spawning was delayed, possibly due to interference with gamonic action. At 0.1 mg/l, the minor protraction of the spawning period may reflect the effect of experimental tank conditions. No seasonal trend was obvious, and there was an exaggeration of the expected fall in condition in mussels exposed to higher concentrations of Endosulfan. In controls, the expected seasonal trend was reduced. 相似文献
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A rapid, automated procedure has been used for differentiation and quantitative determination of siderite, calcite and dolomite, based on the different rates of dissolution of the three carbonate species when reacted with excess 5 mol/litre HCl. The method employs manometric measurements of acid-liberated CO2 with a membrane differential-pressure transducer coupled to a stripchart recorder. Tested on the three carbonate species, singly and in pairs, the technique is discriminatory, sensitive and relatively rapid.Contributions from the Department of Agronomy, University of Kentucky Agricultural Experiment Station in Lexington, and Institute for Mining and Minerals Research of the University of Kentucky. The investigation reported in this paper (No. 83-3-206) is in connection with a project of the Kentucky Agricultural Experiment Station and is published with the approval of the Director. 相似文献
39.
S. S. Cook J. L. Roberts G. M. Hallegraeff A. McMinn 《Journal of Coastal Conservation》2007,11(3):171-181
We assessed the potential impact of a proposed canal development in an estuarine sandflat at Ralphs Bay, Tasmania on intertidal
microalgal productivity and species composition, by comparing it over summer and winter seasons with a well- established (30 year
old) canal estate at Patterson Lakes, Victoria. Pulse amplitude modulation (PAM) fluorometry was used to generate a relative
measure of photosynthetic performance, which combined with microalgal chlorophyll biomass and irradiance provides an assessment
of potential primary productivity. We present a sophisticated mathematical model for calculating benthic microalgal production
and the contribution to total primary production, taking into account sediment light attenuation as estimated from sediment
grain size. Ralphs Bay had a total productive microalgal biomass of 44 mg chlorophyll a m−2 which was six times higher than Patterson Lakes, while the relative productivity of Ralphs Bay was four times greater compared
to Patterson Lakes where productivity was virtually absent in the subtidal zone of the canal waterway. Ralphs Bay exhibited
a more or less homogeneous spatial distribution of microphytobenthos biomass but this was subject to some seasonal variation
in species composition, abundance and productivity. By contrast, at Patterson Lakes biomass distribution, diversity and productivity
was highly spatially variable in the canal system in both seasons. Patterson Lakes exhibited 60% lower microphytobenthos species
richness than Ralphs Bay but little variation in species composition occurred between seasons in the canal estate. This suggests
that the dominant diatom species in Patterson Lakes, Pinnularia yarrensis, Gyrosigma balticum and Pleurosigma salinarum, are well adapted to the disturbance regime within the canal estate. The proposed canal development at Ralphs Bay is estimated
to cause a decrease in microalgal productivity by both reducing available marine substrate (66% reduction) and replacing productive
intertidal phytobenthic habitat with nonproductive canal substrate. These combine to cause a decline in productivity of 92%
with significant flow-on effects predicted for higher trophic levels such as migratory wading birds. 相似文献
40.
Biosensors for detection of mercury in contaminated soils 总被引:1,自引:0,他引:1
Bontidean I Mortari A Leth S Brown NL Karlson U Larsen MM Vangronsveld J Corbisier P Csöregi E 《Environmental pollution (Barking, Essex : 1987)》2004,131(2):255-262
Biosensors based on whole bacterial cells and on bacterial heavy metal binding protein were used to determine the mercury concentration in soil. The soil samples were collected in a vegetable garden accidentally contaminated with elemental mercury 25 years earlier. Bioavailable mercury was measured using different sensors: a protein-based biosensor, a whole bacterial cell based biosensor, and a plant sensor, i.e. morphological and biochemical responses in primary leaves and roots of bean seedlings grown in the mercury-contaminated soil. For comparison the total mercury concentration of the soil samples was determined by AAS. Whole bacterial cell and protein-based biosensors gave accurate responses proportional to the total amount of mercury in the soil samples. On the contrary, plant sensors were found to be less useful indicators of soil mercury contamination, as determined by plant biomass, mercury content of primary leaves and enzyme activities. 相似文献