摘要:

Recent evidence indicates that there has been a reduction in the stratospheric ozone over the northern hemisphere, as well as the Antarctic and Arctic latitudes. This has resulted in an increased penetration of ultraviolet B (UVB) at least as measured at Toronto, Canada, since 1989. If no precautions are observed by the human population, this could eventually result in an increase in the skin cancer incidence. This would be especially true for the most common cancers, that is, the nonmelanoma skin cancers (NMSCs), basal cell carcinomas and squamous cell carcinomas. In addition it has been predicted that the third most common skin cancer, the malignant melanoma, would also increase in incidence. However, the relationship between UVB radiation and melanoma formation is much less clear than it is for NMSCs. Clinically people with a loss or lack of melanin protection such as those with occulocutaneous albinism and vitiligo, or much more commonly, people with light skin, eyes, and hair would be at greatest risk. Also increased UVB penetration could exacerbate certain infections such as herpes simplex. People with UVB-sensitive diseases including solar urticaria, polymorphous light eruptions, lupus erythematosus, dermatomyositis, pemphigus, pemphigoid, Darier's disease, familial benign chronic pemphigus, and certain recessive degenerative genodermatoses would also be potentially more vulnerable.Key words: ozone, ultraviolet B (UVB), skin cancer, photosensitive skin diseases.

ISSN:1208-6053    

DOI:10.1139/a96-001

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

The environmental legacy of 100 years of a metal processing industry is evaluated, based on a case study of ecotoxicological research that has been carried out in the area surrounding a copper refinery, a cadmium alloying plant, and a brass foundry at Prescot, northwest England. Aerial fallout of particulate copper and cadmium has been very localized, but soluble and potentially more toxic forms of the metals have been transported further. Accumulation of Cu and Cd in soils to exceptionally high levels has occurred, with Zn and Pb also highly elevated, but depth profiles, spatial dispersion patterns, mobility, and speciation vary between metals. A very limited effect on tree growth is apparent, although phytotoxic symptoms are readily observed in tree seedlings. Site contamination is reflected in metal concentrations in tree rings. Significant food chain transfer of Cu and Cd to invertebrates and small mammals has occurred, affecting population sizes of invertebrates and producing toxicological symptoms in shrews. Copper may have been a cause of concern for livestock in surrounding rural areas and human ingestion of metals may have been significant in the past, but currently both are likely to be negligible. Impingent metals have led to selection for metal resistance in some plant species; metal tolerance traits in grasses appeared rapidly in lawns in the area and the intensity of tolerance in plants directly reflects the localized degree of contamination. Cellular metal tolerance traits have been induced in trees as an acclimation response to metal contamination. Declining industrial activity in recent years has resulted in unexpected pulses of plant-available soil Cd and of several other metals including Mn, Ca, Mg, and Ni. Metal disappearance rates from surface horizons are also higher than expected following recent cessation of metal processing, and the fate of these transitory metals presents further cause for concern.Key words: heavy metals, ecosystem, food chains, pollution, metal tolerance.

ISSN:1208-6053    

DOI:10.1139/a96-002

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

Daphniidae (Crustacea, Anomopoda) have often been utilized in toxicological studies and environmental monitoring of aquatic systems for a number of reasons, such as their sensitivity to toxins and their ease of culture, and because they are such important members of the zooplankton in so many lakes. The extensive literature on the use ofDaphniaas a bioindicator of environmental pollution with metal ions is critically reviewed. A summary of the data on the toxicity of metal ions inDaphniais presented. These studies have lead to attempts to standardize the use of the bioindicator, as well as the monitoring of procedures. There have also been efforts to derive a relationship between toxicity data and the actual properties of toxins. Such a relationship would be beneficial for predicting the power of toxicity. To date, however, the efforts to establish this relationship have not been satisfactory. This compilation of metal toxicity data and the presentation of the attempts to establish such relationships was carried out in anticipation that it would be useful in future studies that might lead to a universal theory of the effect of metal ion toxicity on aquatic organisms.Key words: aquatic toxicology, bioindicators, Daphniidae, metal ion toxicity.

ISSN:1208-6053    

DOI:10.1139/a96-003

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

Society has been wrestling with the concept of managing forests sustainably for several years. As one of the most widespread of the earth's ecosystems and as a renewable resource providing a wide range of consumptive and nonconsumptive benefits to society, forests have been at the centre of many policy discussions. While much progress was made at the Earth Summit in 1992 and since that time, there are few concrete examples of sustainable forest management in practice. In this paper, some of the key foundations of sustainable forest management are reviewed, including the balancing of economic and environmental objectives in society, the philosophy of ecosystem management, the role of science and technology in forest management, public participation in decision making, and the internationalization of forest issues. To examine the practical implications of these concepts, four very different case studies of attempts to implement sustainable forest management in Canada are examined and discussed. These model forests are part of a network of 10 such sites in Canada, which are linked with several others in Mexico, Russia, Malaysia, and the United States. They combine the interests, mandates, and objectives of government agencies, aboriginal peoples, communities, and many other stakeholders for the purpose of creating a comprehensive vision and program of work aimed at achieving sustainable forest management in the areas concerned. Each model is unique, however, and reflects the local context. The authors conclude that the future of forest management will be based on a government acceptance of delegation of responsibility to such partnerships and on the application of diverse and innovative solutions to forest management issues.Key words: sustainable forest management, model forest, ecosystem management, integrated resource management, public participation, Canada.

ISSN:1208-6053    

DOI:10.1139/a96-004

出版商:NRC Research Press    

年代:1996

数据来源: NRC