Environmental Pollution Series A, Ecological and Biological最新文献

Exposure of the cichlid fish tilapia, Oreochromis mossambicus, to acutely stressful (96-h LC₅₀) levels of naphthalene, toluene or phenol for 4 days did not produce any change in the activities of aspartate and alanine aminotransferases in liver or muscle. However, the stress of 10 weeks exposure to chronically sublethal (50% 24-h LC₅₀) concentrations of the hydrocarbons stimulated the enzyme activities in both the tissues. This change was accompanied in some groups by reduced tissue levels of soluble proteins and free amino acids, suggesting increased tissue proteolysis in these sublethally stressed tilapia.

Two-year-old sugar maple Acer saccharum and northern red oak Quercus rubra seedlings were exposed to all combinations of several levels each of ozone (O₃) and simulated acidic rain. Deposition rates and amounts of simulated rain were normal for eastern North America (12·5 mm of rain twice per week) and levels of acidity in the various treatments ranged between pH 5·6 and 3·0. Plants were exposed to O₃ for 7 h per day on 5 d per week. Concentrations of O₃ were constant and ranged between 0·02 and 0·12 μl litre⁻¹ in the various treatments. Ozone treatments caused significant declines in net photosynthesis in both species, with the largest reductions observed (30% in maple and 20% in oak) after two months in the highest O₃ treatment (0·12 μl litre⁻¹). Reductions in growth as a result of O₃ treatments occurred in sugar maple, but apparently due to the relatively short duration of the pollution treatments, growth reductions were not observed in red oak. Chlorophyll contents in sugar maple leaves increased as a result of O₃ exposure. Simulated acidic rain treatments had no effect on either net photosynthesis or growth in either species and no interactive effects of the two pollutants were observed. The results of this study suggest that sugar maple and red oak are relatively insensitive to acidic rain over the course of a single growing season, but potential long-term effects are unknown. These two species were sensitive to relatively low concentrations of O₃, and ambient levels of O₃ in eastern North America could be having significant deleterious effects on sugar maple and red oak in the field.

One-year-old seedlings of Pinus sylvestris L., representing 20 European provenances of the species from Sweden, USSR, Poland, GDR, FRG, Belgium, France, Hungary, Yugoslavia and Turkey, were subjected to the action of SO₂ (0·75 μl litre⁻¹ ×5 days, 6 h daily). The sensitivity of two-year-old seedlings of the same provenances were also studied under field conditions near an SO₂ and fluoride source. In both experiments there were statistically significant differences in the extent of needle injury between individual populations. Northern provenances (Sweden, USSR) and those from the south (Yugoslavia, Turkey) showed less sensitivity than provenances from the central part of the specie's range. A substantial agreement was found between the extent of necrosis under laboratory conditions and in the field (r = 0·44, significant at α = 0·1). A comparison of the net photosynthesis of control plants with needle necrosis under both treatment conditions has shown that there is a positive significant correlation.

The accumulation of fluoride by fully expanded basal leaves of grapevines was measured through two seasons in ten vineyards 9–25 km downwind of an aluminium smelter near Cessnock. Accumulation was linear with time until mid-summer then declined somewhat as leaves aged. Heavy rainfall and lowered emissions reduced accumulation. The impact of fluoride on the vines each season could be readily assessed from the leaf fluoride concentration in January, just prior to harvest.

Fluoride accumulation by grapevines was assessed in four districts each January from 1981 to 1983. At Griffith and Mudgee, two districts which lacked an industrial source of fluoride, vine leaves did not accumulate fluoride (<2 μgFg⁻¹). At Muswellbrook, vines growing 15–37 km downwind of a power station generally had slightly elevated leaf fluoride concentrations (1–10 μgFg⁻¹), but certain higher values were recorded (18–27 μgFg⁻¹) in vineyards under the direct influence of the plume. These higher values did not produce leaf necrosis. At Cessnock, 9–23 km downwind of the aluminium smelter, elevated leaf fluoride concentrations (4–42 μgFg⁻¹) were also recorded, with highest levels 9–11 km from the smelter. These levels did not produce leaf necrosis in well managed vineyards. In certain non-irragated vineyards, flouride accumulation was retarded by water-deficit stress when experienced throughout the growing season. In contrast, where severe water-deficit stress was not experienced until mid-summer, certain leaves which had accumulated 26–36 μgFg⁻¹ developed marginal necrotic lesions which reduced effective leaf photosynthetic area by 5–10%.

Effects of Emisan-6 (2-methoxy ethyl mercury chloride or MEMC) and mercuric chloride (HgCl₂) on the ATPase activity of Westiellopsis prolifica were studied. At low concentrations of mercuric chloride the total ATPase (Mg²⁺, Na⁺, K⁺-dependent ATPase) activity decreased in the initial period of exposure, but increased with an increase in exposure time. With both the test materials, the enzyme activity then showed significant enhancement when compared to control values. However, after the 6th day of exposure to Emisan-6, and after the 9th day for HgCl₂, the level of activity declined with an increase in the period of exposure. When both the exposed cultures were transferred to toxicant-free nutrient medium, a significant recovery was observed, in all cases.

The radioactive tracer ²¹⁰Pb has been used to examine the foliar uptake and redistribution of lead in three plant species grown under glasshouse conditions for periods of 8–12 weeks. In radish a small amount (0.05–0.28%) of the lead applied to the leaf surfaces was transported to the swollen storage organ. This movement occured through intact and damaged cuticles, with an indication of an enhanced effect for damaged cuticles. Carrot plants absorbed and transported a fraction (0·43%) of the applied activity. By the end of the experiment this had reached the lower portion of the leaf petiole. Transport of lead to the tap root was <0·01% of that applied. In the case of dwarf French beans no movement of lead into pod or seed tissue was detected. It is estimated for radish that foliar absorption of lead and transport to the root could account for about 35% of the internal lead burden of root storage tissues. For carrot this pathway contributes about 3%.