Environmental Pollution (1970)最新文献

Mine wastes from a lead-zinc mine have been spread by water action over a flood plain and the deposits are not fully revegetated after a lapse of 40 years. The nutrition of oats, subterranean clover and poplar grown in the contaminated material and in mixtures of it with an uncontaminated control soil was investigated. For all species, high acidity and availability of zinc were principal factors that were counteracted by the application of lime. However, a depression in growth of clover in both soils was observed with high rates of lime. This was subsequently shown to be associated with boron deficiency in both cases. Hence, in the reclamation by liming of contaminated areas, consideration should be given to the inclusion of boron as a nutrient just as it should be when lime is applied to agricultural soils similar to the control soil.

The relative part of the different forms of the carbon constituting the hydrocarbons in an in vitro topped crude oil biodegradation experiment by soil bacteria, in 21 days at 25°C, was determined. The abiotic loss (evaporation) was estimated to be 20% of the initial carbon and the global biodegradation, comprising total and primary biodegradation, reached 21%. The total biodegradation included the carbon transformation into CO₂ (mineralisation) and into biomass, estimated respectively at 13·7 and 5·6% of the initial carbon. The primary biodegradation, as measured by the organic carbon dissolved in the medium, represented 1·5% of the initial carbon. Another estimation of the global biodegradation, independently obtained by the residual weight of the chloroform extract, gave a similar result (22%). An analysis of the chloroform-extracted residue, performed by column fractionation and gas-liquid chromatography, showed that the saturate fraction was 40% degraded and the aromatic fraction, 18%. The pristane and phytane were completely biodegraded and no increase of long chain paraffins was noted. A statistically highly significant absolute increase of the asphaltic fraction, due to accumulation of extracellular products, was shown.

Potted young plants of various trees and shrubs (clones), exposed in the vicinity of a motorway, showed premature senescence. Investigations with two species, birch Betula pendula and sallow thorn Hippophae rhamnoides, showed that peroxidase activity in July and September, and ethylene production during autumnal senescence, were significantly increased. Premature leaf abscission was observed in all investigated trees and shrubs (ash Fraxinus excelsior, birch Betula pendula Roth, dogwood Cornus sanguinea, honeysuckle Lonicera xylosteum, oak Quercus robur and sallow thorn Hippophae rhamnoides) along the motorway. It is supposed that consitions associated with traffic are responsible for these effects. Slight salinity in the soil of the pots had no significant effect.

Nitric oxide is the predominant air pollutant in glasshouses in which hydrocarbons are burnt to provide heating or CO₂ enrichment of the atmosphere. Some circumstances in which this pollution can increase or reduce the growth of tomato Lycopersicon esculentum Mill. have been identified. A factorial experiment involving varied levels of soil fertility showed that when the amount of nitrogen available in the soil is low, the plants can tolerate, and even benefit from, nitric oxide in the atmosphere. Even at low levels of soil nitrogen there are, however, deleterious effects of the pollutant if its concentration rises above a critical level; under the conditions of the experiments reported in this paper this level was between 40 and 80 pphm.

The response to nitric oxide differs markedly among varieties of tomato. One modern F₁ hybrid (Sonato) was greatly stimulated in its growth by 40 pphm nitric oxide. This may explain the success of this variety in commercial glasshouses that are normally polluted with nitric oxide during CO₂ enrichment.