Environmental Pollution Series A, Ecological and Biological最新文献

Feeding behaviour and breeding success in an insectivorous bird, the little bee-eater Merops pusillus, were monitored in an area of southern Somalia treated five times with drift sprays of the insecticide, endosulfan, applied at 14–41 g ha⁻¹. Birds fed mainly on bees and wasps but flies and beetles were also commonly eaten. After the heaviest spray application day-flying insects virtually disappeared from one area for 24h; the feeding rate fell and breeding failure at three nests followed. However, at the end of the spraying operation, fledging success in the sprayed area was generally the same as outside. Disrupted laying and incubation, and co-operative breeding amongst little bee-eaters in Somalia, may indicate a poor food supply and a population particularly vulnerable to insecticidal treatments.

Simulated rain acidified with H₂SO₄ to pH 3, compared with non-acidified rain (pH 5·3) and distilled water (pH 5·5), increased the leaching of major cations from a layer of decomposing Sitka spruce litter and underlying F horizon over a 3-month incubation period at 10°C. Largest relative increases in leaching were observed for Mn²⁺ > Mg²⁺ > NH₄⁺ > Ca²⁺. Acid rain (pH 3) decreased the amount of total organic carbon, Fe³⁺ and Al³⁺ leached from the Sitka spruce litter and soil layer. Sterile litter leachates obtained from all treatments supported fungal growth equally well. Acid rain-produced leachates, however, impaired initial bacterial growth of cultures isolated from forest soil and also in mixed soil isolates. The same cultures, however, were not affected by the high Mn²⁺ concentration of the leachates, which therefore was not responsible for this observation. At the end of the raining period, the rate of respiration in the F horizon was significantly reduced in soils previously treated with acid rain, compared with the non-acid rain treated soils.

Sediments were exposed to five concentrations of the plasticizer di(2-ethylhexyl)phthalate (DEHP) and the effects on sediments oxygen uptake were assessed. The sediments were taken from an eutrophic lake and consisted of ‘undisturbed’ sediment with overlying lake water. The community respiration in the sediment was inhibited by DEHP. The oxygen uptake from uncontaminated sediment was significantly higher than from sediments containing DEHP. The decrease in microbial activity in contaminated sediment cores was positively correlated to increasing levels of DEHP in the sediment. At concentrations of 25 μg DEHP g⁻¹ and higher the sediment respiration consisted of chemical, rather than biological, oxygen consumption.

In 1981, we studied lead concentrations and reproductive success in freeliving European starlings Sturnus vulgaris nesting within the verges of two Maryland highways with different traffic volumes, Route 197 (average daily traffic volume [ADT] = 10 800 vehicles) and the Baltimore-Washington Parkway (ADT = 52 500 vehicles) and a nearby control area. Concentrations (mgkg⁻¹ dry weight) of lead in the ingesta (84–94 mg kg⁻¹), carcasses (4·0–9·6 mgkg⁻¹) and feathers (6·8–52 mgkg⁻¹) of Parkway nestlings and adults were 3 to 13 times those found in starlings from the control area, whereas lead concentrations in the ingesta and tissues of starlings from the verge of Route 197 were similar to those of controls. Activity of δ-aminolevulinic acid dehydratase (ALAD) in red blood cells (RBCs) of adult and nestling starling from the Parkway was depressed from 43 to 60% compared to controls. RBC ALAD activity in adults from nests along Route 197 was similar to that of adult starlings from the control area, but that of their young was depressed 17%. Haemoglobin concentrations (−16%) and haematocrits (−10%) in Parkway nestlings were depressed compared with those of nestlings from the other two study areas, whereas those of adults were not affected. Clutch size, number of young hatched and the number of young in nests 1 to 3 days before fledging were similar among sites, as were body weights of adults and prefledging weights of their young. However, brain weights of Parkway nestlings were lower (P<0·05) than those of nestlings from the other study areas. Results suggest that lead within verges of major highways probably does not pose a serious hazard to adult ground-foraging songbirds. However, the effects of lead-induced reductions in haemoglobin concentration, haemotocrit, RBC ALAD activity and brain weight on the postfledging survival of their young are not known.

Moles (Talpa europaea) and common shrews (Sorex araneus) were trapped in 1977 at three 5 km intervals on two transects radiating NE and SE from an aluminium reduction plant on the island of Anglesey, North Wales. Earthworms (Lumbricidae) were collected from the same transect locations. Materials were also obtained from elsewhere for comparison. For all materials, highest fluoride concentrations were found within 1 km radius of the reduction plant.

Moles from within 1 km of the reduction plant had a mean bone fluoride content of 7740 μg g⁻¹ (range 5160-11 100 μg g⁻¹); elsewhere on the island the overall mean was 1294 μg g⁻¹ (range 42 to 3125 μg g⁻¹). With the exception of animals within 1 km of the reduction plant, bone fluoride in moles showed no relationship to distance from the plant along either transect (P > 0·7 at least). Moles from areas more than 15 km from the reduction plant had a mean bone fluoride concentration of 971 μg g⁻¹ (range 40 to 2200 μg g⁻¹). Tooth wear index in this sample was only half that found in moles from within 15 km of the reduction plant (P < 0·001).

Common shrews had an overall mean bone fluoride concentration of 1404 μg g⁻¹ (range 82 to 8600 μg g⁻¹). Concentrations decreased with distance from the reduction plant, consistent with airbone carriage of fluoride from the stack at the plant (P < 0·05).

Apart from the immediate vicinity of the reduction plant, total fluoride concentration in earthworms showed no relationship to distance from the plant. Their fluoride content was considered to be largely due to soil contained in the gut.

Soybeans (Glycine max (L.) Merr. cv Hodgson) were exposed in the field to seasonal 7-h average concentrations of 0·017, 0·035, 0·060, 0·084 and 0·122 μl litre⁻¹ ozone using open-top chambers and ambient plots. Dose-response studies were conducted on growth and yield. Negative linear relationships were found between both growth and yield and ozone exposure. The regression equation: yield= 12·82 − (48·17 × O₃), with yield in grams per plant and O₃ as the seasonal 7-h average, expresses one relationship. Compared with the yield in charcoal filtered air (0·017 μl litre⁻¹), losses ranged from 8% in the 0·035 μl litre⁻¹ treatment to 41% in the 0·122 μl litre⁻¹ treatment.

Aboveground biomass was a good indicator of ozone stress; five weeks after the ozone treatments were initiated, a negative linear relationship was found between ozone exposure and aboveground biomass. In contrast, the percentage of biomass allocated to leaves, stems and pods did not change until after 6 to 7 weeks of exposure to ozone. The change in allocation of biomass was the result of accelerated senescence of older leaves. At final harvest, a lower percentage of aboveground biomass was found in pods and seeds of plants exposed to higher ozone concentrations.

As a continuation of our earlier studies on the impact of heavy metals on aquatic organisms (Abbasi & Soni, 1984), the behavioural responses and survival of the teleost Nuria denricus exposed to different levels of zinc (II), cadmium (II) and lead (II) were studied. Safe concentration (SC) values of the metals were determined with the help of computer-aided long-term bioassays.

Comparisons of the SC with the minimum allowable levels of the corresponding metals in drinking water, effluents, irrigation water and fisheries revealed that, except for a few cases, the existing national and international water quality standards for various water uses are higher than the SC. The disparity between the SC and the permitted levels of zinc and cadmium was especially noteworthy, indicating the need for a thorough re-evaluation of the toxicity and safe levels of these metals.

A factorial experiment in a controlled environment with four levels of particulate nickel and four levels of rooting medium nickel was used to obtain response surfaces describing the effects of these sources of nickel on growth and on stem nickel content of soybean plants. Covariate measurements were used to increase precision. The response surfaces were displayed as contour plots to aid in the interpretation of joint action of the two sources. Both particulate and rooting medium nickel decreased plant growth and there was generally additive joint action when the sources were combined. Growth response patterns differed among leaves, stems and roots and the two sources differed in their effect on specific leaf weights and shoot/root weight ratios. Tissue dry matter concentration was altered in both stems and roots. Stem tissue accumulation of nickel was mainly affected by the particulate concentration.