Environmental Pollution Series A, Ecological and Biological最新文献

Seasonal changes of mercury accumulation in organs and tissues of the black-eared kite were investigated between the pre- and post-moult (April–November). The mercury concentration was high in the feathers, kidney and liver, and low in the skin and bone. About 70% of the mercury burden in the whole body was in the feathers. While the concentration of mercury decreased in most of the tissues during moulting (June–September), it remained constant in feathers throughout. This indicates that moulting is a major excretory pathway for mercury and the age-dependent accumulation of mercury is virtually absent in this species. The question of which kite feathers should be selected as indicators of mercury pollution in birds is discussed.

Plants of maize Zea mays L. and soybean Glycine max L. were treated with fly ash, a waste product of coal-fired electric generating plants, at the rates of 2, 4 and 8 g m⁻² day⁻¹ for 30 consecutive days between 15 and 46 days of plant age. At the lower two rates, both crops showed an increase in plant height, metabolic rate, content of photosynthetic pigment and all dry weight fractions measured. This response was, in part, due to correction of boron deficiency by fly ash deposition. The highest dusting rates, however, caused reductions in pigment content and dry matter production. Reduction in plant growth at the highest dusting rate was attributed chiefly to the excessive uptake and accumulation of boron, and alkalinity caused by excessive soluble salts on the leaf surface.

The considerable logistical problems involved in large-scale monitoring networks could be overcome in part by establishing a biological water quality network of stations, operated by high schools. Measurement of benthic invertebrate community structure obtained in a pilot project involving five schools produced results that were reliable with regard to collecting and identification efficiency. Early results from a network that includes more than 20 teachers and 500 students at 12 schools show an ability to identify changes in stream water quality.

SEM studies were made of the effects of SO₂ and NO₂ pollution on the leaves of Commelina communis. Plants at the two-leaf stage were exposed to a mixture of 100 nl litre⁻¹ SO₂ and 100 nl litre⁻¹ NO₂ for 10 days in recycling-type fumigation chambers. The first visible symptoms of injury appeared after 4 days on the abaxial surface of the oldest leaf in the form of glazed light brown patches along the margins. These symptoms also became visible on the adaxial leaf surface by the seventh day of exposure. SEM analysis of leaf epidermis showed that control plants had evenly distributed surface waxes while fumigated plants had wax accumulated in small heaps with large denuded areas. The palisade cells in fumigated leaves became flaccid due to loss of turgidity and there was a complete collapse of spongy tissue. Commelina communis thus appears to be extremely sensitive to an environment containing SO₂ + NO₂.

Recolonisation of macrobenthic invertebrates in a tropical stream perturbed by pesticide treatment and associated human activities is discussed. The benthic community, dominated by Chironomidae, Baetidae and Naididae, was stable during the predisruption phase. The disruption severely reduced the standing crop and the diversity of macrobenthos. The recovery of the habitat was rapid. In spite of low diversity, high densities of invertebrates were recorded in the recolonisation phase. Naidids and chironomids were the most successful recolonisers while other groups recovered slowly. Most of the recolonising taxa occurred here during the pre-disruption phase and there were only a few new colonisers. The succession of recolonising taxa was distinct. The abundance of naidids and chironomids was extremely high in the initial stages of recolonisation and thereafter decreased rapidly.

The effect of long-term respiratory chamber exposure to aerosol containing metal particles derived from a nickel refinery dump on the alveolar macrophage (AM) phagocytic and enzymatic activities of Wistar rats was investigated. The number of AM lavaged from the lungs of the exposed group was significantly higher than in the controls (P < 0·001). The lung lavage exhibited some pleomorphic cells. The high number (93%) of AM with phagocytised metal particles was detected. In vitro the lavaged cells showed a significant increase in ⁵¹Cr incorporation compared to the control group. A statistically significant enhancement of AM lysosomal (acid phosphatase and β-glucuronidase) enzyme activities (P < 0·05, P < 0·01) was found in the exposed animals, whereas both the plasma membrane (ATPase and 5′-nucleotidase) enzyme activities were clearly reduced (P < 0·001). Serum cytotoxicity in the exposed animals was slightly elevated.

The acute toxicity of nickel to first and second instars of Chironomus riparis was determined using larvae from a laboratory culture. First instar larvae were found to be significantly more sensitive to nickel than second instars with 48h LC₅₀ values of $\text{79·5 ± 3·7}\text{mg litre}{}^{\mathrm{-1}}$ Ni and 169 ± 10 mg litre⁻¹, respectively.

Longer term chronic toxicity tests (30 days), in which larvae were allowed to develop from eggs until just prior to pupation, indicated that nickel concentrations of up to 25 mg litre⁻¹ appeared to have little effect on the percentage hatch of C. riparis. The growth of larvae was, however, significantly reduced at the lowest nickel concentration (2·5 mg litre⁻¹) tested compared with control larvae. A maximum acceptable toxic concentration (MATC) for the effect of nickel on growth was estimated to be 1·1 mg litre⁻¹ Ni. This value is substantially lower than the LC₅₀ value calculated for first instar larvae and indicates the importance of conducting longer term toxicity tests when assessing the pollution tolerance of an organism.

Absorption, distribution and release of squalane were studied in rainbow trout fed a diet containing 0·05% of this alkane.

Whether faeces were collected automatically from pond water or by manual stripping, the estimated squalone absorption was ca. 40% of the dose.

After 3 months of exposure, the residues in the whole body reached a steady equilibrium value in the 16–18 μg g⁻¹ range. The most pronounced deposition occurred in the liver (1671 μg g⁻¹ after 10 months) while the concentration of squalane in the adipose tissue was below 2 μg g⁻¹.

During the depuration period, half of the contaminated trout were fed a squalane-free diet, while the others were starved. After 2 months the body burden amounted to 65% and 80% of the alkane previously accumulated in starved and fed trout, respectively. In the starved group, 43% of the squalane initially stored in the liver was lost, whereas the loss in the fed fish liver was 52%.

These results were compared with data regarding other alkanes previously investigated.

Lettuce grown hydroponically in growth chambers was exposed daily for 10 days to simulated acid rain at pH 3·3, 4·1 and 5·6 with and without 1·5 mg litre⁻¹ 2,4-DP. Increasing acidity reduced contents of Mn, Fe, Mg and Co, increased visible damage, but did not affect yield. Growth was stimulated by 2,4-DP at pH 4·1 and 5·6 but inhibited at pH 3·3. Contents of Zn and Co, as well as visible damage, were affected in a similar synergistic way. Contents of stress-ethylene 8 and 18 h after exposure indicated that the mode of action for synergism may be due to the pH-pK_a-dependent cuticular penetration.

The effect of car exhaust lead pollution on pollen germination and seed viability of two roadside weeds, Cassia tora L. and Cassia occidentalis L., was studied. A decrease in the percentage of pollen germination and seed viability was observed in plants growing near Highway No. 8. With increasing distance from the highway pollen germination and seed viability improved, and at a distance of 60 m from the road the percentage of pollen germination and seed viability became closer to normal. The decrease in pollen germination and reduction in viability were directly proportional to the amount of lead accumulated in the plants.