摘要:

Copper pipes in the water distribution system are widely used all over the world. Corrosion of the pipes causes elevated copper levels in the drinking water. The corrosion depends on the water composition and the stagnation time of the water in the pipes. Low pH is a main factor determining the release of copper, and high alkalinity is also an important contributing factor, especially at a low pH. This is in contrast to corrosion of iron pipes, which is prevented by increasing the alkalinity. Copper in drinking water may contribute significantly to the dietary intake of copper, and sometimes drinking water is the major source. However, it is difficult to calculate the intake of copper from drinking water, as the concentrations can vary one or two orders of magnitude, depending on the flushing habits. Gastrointestinal effects (e.g., nausea, vomiting, diarrhea, and abdominal pains) have been reported after exposure to high concentrations of copper in drinking water. Owing to lack of data, the tolerated level of copper in water can not be firmly established, but guideline values of 1-2 mg/L have been recommended. A higher sensitivity in newborns to elevated copper exposure has been suggested. Release of copper from the pipes will also result in elevated copper concentrations in waste-water sludge and may limit the use of sludge for agricultural purposes. The critical concentration at which copper must be considered from ecotoxicological aspects depend on the biota and exposure conditions at the actual site. Major effects due to elevated copper concentrations in the environment includes decreased growth of plants, disturbed reproduction in several species of invertebrates, and copper poisoning in livestock and fish. Aquatic organisms, especially certain species of crustaceans, have the highest sensitivity to copper toxicity. Effects on fish can be significant already at levels below 0.01 mg/L. The consequences of the extensive and widespread environmental pollution of copper from the intentional use of copper as piping material need to be investigated and thoroughly evaluated.Key words: copper, drinking water, plumbing, health effects, toxicity, sewage sludge.

ISSN:1208-6053    

DOI:10.1139/a98-009

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

In Canada, the eastern tolerant hardwood forest is potentially at risk from air pollution. Surveys indicate that, overall, the condition of hardwood forests has either not changed or has marginally improved. However, stands growing on shallow, poorly buffered soils have a higher frequency and severity of decline symptoms, and some of these stands have continued to decline, in contrast to the general trend. In Ontario on the most sensitive sites (<6 mequiv. exchangeable bases/100 g), decline symptoms increased coinciding with a decrease in B horizon pH and base saturation and with an exchangeable Al increase. On these sites the chemical analysis of foliage, root, xylem, and soils indicate that nutrient deficiencies, nutrient imbalances, or metal/nutrient antagonism are related to stand decline. There is a consistent spatial relationship between white birch decline in the Bay of Fundy area and acidic sea fog. Acid fog injures and leaches foliage and hastens soil acidification, leaving the stands weakened and making them more sensitive to stress, particularly drought. Some recent studies suggest that forest growth rates are declining and that the relationship with climate has deteriorated, implying that the forests are responding to a regional, nonclimatic, nonpathogenic stress. This could be a response to altered forest nutrient cycling associated with acidic deposition and chronic O3exposure. A study of sugar maple in Ontario estimated that after the mid-1960s growth has declined between 0.66 and 0.96 m3·ha-1·year-1, and that the decline was greatest on poorly buffered soils. Without enhanced forest management and more stringent air pollution regulations, the sustainability of forest productivity in Eastern Canada is likely to be difficult because of air pollution and soil fertility losses.Key words: dendroecology, acid deposition, ozone, forest decline, sugar maple, climate change.

ISSN:1208-6053    

DOI:10.1139/a98-008

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

This survey represents a review of current knowledge concerning nickel and its compounds in the Finnish environment. Nickel, a naturally occurring element, is ubiquitous in the environment, especially in the divalent state. It was identified in the middle of the 18th century and its extraction process developed in the middle of the 19th century. In Finland, primary nickel production takes place by the direct high-grade nickel matte flash smelting process. Domestic production of nickel increased from 16 900 t in 1990 to 35 285 t in 1997. As a result of its versatile properties, more than 300 000 end-use applications of nickel have been reported. Its major use in Finland is in the production of stainless steel. In 1996 the release of nickel from industrial sources in Finland was as follows: 47 t to the atmosphere, 19 t to the aquatic environment, and 150 t to landfills and soils. The highest emissions stemmed from fuel-fired utility boilers. Nickel emissions to the atmosphere from the Harjavalta nickel smelter decreased from 7 t in 1993 to 1.2 t in 1996 as a result of technological developments and better gas cleaning equipment. In this study, nickel in the air, stream waters, soils, and lake and river sediments have been examined. It is noted that the background concentration of nickel in the air is about 0.5 ng·m-3, and nickel in stream water varies from 0.14 to 4.0 µg·L-1. There was no significant change of nickel concentration in arable lands between 1974 and 1987. In addition, nickel concentrations in terrestrial and aquatic species in Finland have been touched upon.Key words:nickel, occurrence, emissions, uses, Finnish environment.

ISSN:1208-6053    

DOI:10.1139/a99-001

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

River dolphins are among the world's most seriously endangered species, and the baiji (Lipotes vexillifer), endemic to the Yangtze River, China, is likely to become extinct in the near future. Here we review the status of the obligate river dolphins (baiji, bhulan,Platanista minor, susu,Platanista gangetica, and boto,Inia geoffrensis), discuss the threats they face, and present recommendations for their conservation. River dolphins are particularly vulnerable to the activities of humans because of their restricted habitat. Threats vary geographically in their importance, but generally include accidental killing during fishing operations, depletion of prey from over-exploitation, and habitat loss and population fragmentation from water development. Deliberate killing for dolphin products also threatens the animals in some areas. Recommendations include (among others) the following: (i) establishing meaningful protected areas, (ii) raising public awareness on the ecological and cultural value of river dolphins, (iii) training local workers in conservation techniques, (iv) managing fisheries to reduce accidental killing and ensure the sustainability of prey, and (v) adopting conservation strategies that incorporate the ecological integrity of riverine environments.Key words: River dolphins,Platanista, Lipotes, Inia, Orcaella, Neophocaena, Sotalia, water development, river ecosystems.

ISSN:1208-6053    

DOI:10.1139/a99-002

出版商:NRC Research Press    

年代:1998

数据来源: NRC