Determinants in the perceptions of visual blight

Research on visual blight has been predominantly qualitative and has pointed out salient attributes of blight: that it is durable, visually demeaning, and somehow aesthetically depressing. Data from a national sample (n=3005) are used in this study to measure the effect of demographic variation on the perception of visual blight. The perception of blight shows marked and regular variation with socioeconomic status, marital status, and religiosity.Harris data for this study was purchased with funds from the Shell Foundation. The author wishes to acknowledge Robert Q. Hanham, whose assistance proved invaluable.     

The effects of low concentrations of particulates from paper mill effluent on the macroinvertebrate community of a fast-flowing stream

The effects of a paper mill effluent on the macroinvertebrate community were assessed for the riffle areas of a large fast-flowing stream, the lower reaches of the Saranac River of northern New York State, U.S.A. The effluent caused few changes in dissolved oxygen concentration, pH, biochemical oxygen demand, temperature or nutrient content; however, significant differences in transmitted light, concentrations of particulates and accumulated debris on the substrate were observed. A moderate decrease in invertebrate diversity correlated with increased levels of particulates and substrate debris. An analysis of the response of invertebrate functional groups revealed the effluent had little effect on the density of gathering collector organisms. The functional groups most severely reduced in density were the filtering collectors and scrapers. Predators showed a moderate reduction in density in response to the effluent. The alterations in invertebrate densities were attributed largely to the alterations in seston and substrate caused by the introduction of particulates composed mainly of paper fiber and inert dye.     

Industrial melanism in the spittlebug Philaenus spumarius (L) (Homoptera: Aphrophoridae)*

The visible polymorphism of the spittlebug, Philaenus spumarius, has been investigated in the vicinity of a smokeless fuel factory in the Cynon Valley of south Wales. The factory is a significant source of local particulate air pollution. A striking relationship exists between the combined frequencies of the eight dark (melanic) morphs and proximity to the factory. Maximum melanic phenotype frequencies of over 95“, occur in both sexes immediately adjacent to it and decline to levels normal for south Wales 1.5–6 km away, depending on direction. This relationship is largely confined to sites within the valley; samples from adjacent localities outside it have melanic frequencies within normal limits for the south Wales area. Maximum melanic phenotype frequencies in the Cynon Valley are far higher than any known from elsewhere in the species range in Europe, Asia and North America. No consistent difference is apparent in total melanic frequency between males and females at any of the sites in this study. However, marked differences exist between the sexes in the relative contributions of the eight melanic phenotypes to the overall association with the factory. For females the industrial melanism is entirely attributable to the group flanicollis + gibbus + leucocephalus (mainly leucocephalus) whereas in males both this group and the group quadnmaculatus + albomaculatus + leucopthalmus contribute to the relationship. It is suggested that this relationship is due to the selective effects of the local air pollution from the factory. The exact nature of the selection involved is as yet uncertain; it would appear to be strong since the local adaptation involved has developed in a maximum of 40 generations since the factory was opened. Finally, comparison is made with two other insects, a ladybird and a moth, in which high frequencies of melanic forms are also associated with this pollution source.     

Compounds in urban air compete with 2,3,7,8-tetrachlorodibenzo-p-dioxin for binding to the receptor protein

Acetone extracts of filter-collected urban airborne particulate matter contain compounds which can competitively inhibit 2,3,7,8-[1,6-3H]tetrachlorodibenzo-p-dioxin (TCDD) binding to the rat liver TCDD-receptor protein. The concentration of conventional polycyclic aromatic hydrocarbons (PAHs) or chlorinated dioxins and dibenzofurans cannot account for more than 1-30% of the observed competition for [3H]TCDD binding to the receptor protein. The difference in potency between samples collected in urban areas during different periods of the year and a background sample is 25-400-fold. Collecting samples in the presence of increased concentrations of nitrogen dioxide, nitrous acid, nitric acid or ozone did not increase the amount of compounds with receptor affinity. However, with nitrogen dioxide and especially with nitric acid, a substantial increase of the mutagenic effects in the Ames Salmonella assay in the absence of mammalian activation as well as a degradation of several PAHs were noted. Affinity for the TCDD-receptor protein, mutagenicity in the absence of mammalian metabolic activation in the Ames Salmonella assay and PAH-content are characteristics of urban particulate matter showing the presence of compounds, that represent potential health risks. The compounds with affinity for the receptor may constitute a group of substances different from both conventional PAHs and direct-acting mutagens.     

A comparison of sperm morphology and silver nitrate staining characteristics in the domestic ferret and the black-footed ferret

Ejaculated sperm from the domestic ferret (Mustela putorius furo) and the black-footed ferret (Mustela nigripes) were compared for differences in morphological abnormalities and argentophilic protein distribution. Thawed domestic ferret sperm was also compared to fresh sperm to determine whether there were any effects on cell morphology due to cryopreservation. There were statistically significant differences between the two species of ferret in two of the categories scored. The domestic ferret had a higher frequency of cells that were bent in the midpiece and in the principal piece, and a higher frequency of headless and tailless cells when compared to the black-footed ferret. There were no statistically significant differences in cell morphology between the fresh and cryopreserved ejaculates of the domestic ferret employing a standard egg yolk cryoextender. Silver nitrate staining distribution was different between the two species in both the head and tail region.     

Notes on the use of wood refugia by Physella heterostropha (say) in a thermally disturbed swamp

Physella heterostropha size distributions and densities were measured in Pen Branch delta, a thermally altered swamp of the Savannah River, South Carolina. During cessation of thermal input, measurements were taken in a highly impacted area and more natural area. Of the three substrates sampled, logs, small woody material and benthos, snail density was highest on small pieces of submerged wood and < 20% of the snails on logs were out of the water. Following resumption of thermal input, snail density was four times higher on logs than previously measured. Snails responded to elevated water temperatures by congregating in a narrow band slightly above the water. Snail size did not appear to affect their response. However, the thermal history of the snails influenced their behaviour and survival rates. Logs may be a potential refuge for snails when water temperature are greater greater than 38°C. However, our results indicate that long-term survival in this manner may be impossible.     

二氧化硫对墨西哥豆瓢虫的影响

空气污染对害虫的影响,国内尚无研究报道。本文报道了作者在美国农业研究中心植物胁迫实验室进行的部分工作。实验结果表明,在0.30ppmSO_2的作用下,墨西哥豆瓢虫(Epilachna varivestis)的取食量和蛹重增加;与未受污染的寄主植物相比,豆瓢虫偏食受污染的植物;而且有嗜食含较高糖分寄主植物的倾向;在污染空气中长成的成虫可消耗更多的植物物质。     

EDU and ozone protection: Foliar glycerolipids and steryl lipids in snapbean exposed to O3

Effects of the antiozonant EDU, N-[2-(2-oxo-1-imidazolidinyl) ethyl]-N'-phenylurea, on the content and composition of foliar lipids in snapbean ( Phaseolus vulgaris L. cv. Bush Blue Lake 290) before and after a single, acute ozone (O₃) exposure were assessed. Pretreatment with EDU conferred protection against O₃-induced necrosis and losses of glycerolipids and chlorophyll. Systemic treatment of snapbean plants with EDU did not significantly alter membrane lipids in the first trifoliate leaf. Leaves of untreated controls had lost ca 50% of both galacto- (GL) and phospholipids (PL) by the end of a 3 h exposure to 0.4 μl l⁻¹ O₃. A decline in the ratio of mono- to di-galactosyldiacylglycerol (MGDG/DGDG) was associated with the loss of GL, and a decline in the ratio of linoleic to linolenic acid (18:2/18:3) was associated with the loss of PL in untreated controls. EDU-treated plants showed no significant loss of foliar GL and PL. The MGDG/DGDG ratio declined only slightly, and the 18:2/18:3 ratio in PL increased during O₃ exposure of EDU-treated seedlings. The level of total membrane sterols, including free sterols (FS), acylated steryl glycosides (ASG) and steryl glycosides (SG), did not change during O₃ exposure of either treated or untreated plants. However, in the controls the proportions of ASG and SG increased at the expense of FS, and the ratio of stigmasterol/sitolsterol increased in FS and SG. In EDU-treated plants, a relatively small increase in SG was offset by a decrease in FS, and there was no change in the stigmasterol/sitosterol ratio in ASG, SG or FS. The results indicate that EDU may confer tolerance to O₃ through induction of enzyme systems involved in the elimination of activated oxygen species and free radicals.     

Nitrification and nitrate uptake: Leaching balance in a declined forest ecosystem in eastern France

Nitrate uptake and leaching were measured during one year in a declined fir forest on the Vosges highlands (eastern France), in order to investigate whether excess nitrification could be responsible for a deleterious acidification of the ecosystem. Nitrate uptake by the vegetation was active mainly from spring to early fall, and then reached about 66 kg N ha^-1. No significant leaching loss occurred during the growth period of the vegetation. Significant nitrate leaching occurred in winter (about 17 kg N ha^-1). During fall and winter the nitrification rate was of the same magnitude as values reported for other ecosystems, and, thus, was not considered to be abnormaly strong. No abnormal temporal discoupling of nitrate production and nitrate uptake occurred in the ecosystem, and forest decline must therefore have some other cause.     

Uptake of phosphate from soils and fertilizers as affected by soil P availability and solubility of phosphorus fertilizers

Fertilizers labelled with ³²P were used to measure amounts of phosphorus, P_s and P_F, taken up by Lolium perenne from available soil P and from P fertilizer respectively, when applied at a rate of 66 mg P·(kg soil^–1) in greenhouse experiments. The quantity P_s of phosphorus taken up from soil in the presence of P fertilizer was compared to the quantity P_o taken up from soil without P fertilizer. The quantity (P_s–P_o) is positive for low P_o values, i.e. in soils poor in available phosphorus, but is negative for high P_o values indicating that an input of P fertilizer can induce a decrease in the utilization of available soil phosphorus. Moreover, for a given soil, the quantity (P_s–P_o) depends on the chemical form of the fertilizer. The standard method of evaluation of P fertilizer efficiency is based on the assumption that P_s=P_o, but P_s can differ from P_o. This result can explain the contradictory data published from field experiments about the efficiency of the various P fertilizers.