摘要:

Global emission inventories, being the key information for the global budgets of trace metals, have become available only recently. The latest information on emissions and sources of trace metals on a global scale is presented in this paper. As the global assessments are prepared on the basis of estimates of regional emissions, these latter data are also reviewed here. A comparison of the worldwide atmospheric emissions from natural and anthropogenic sources suggests that various human activities are the dominant source of many trace metals, including As, Cd, Pb, and Zn. A comparison of the atmospheric and aquatic emissions indicates that, for most of the trace metals, the annual anthropogenic inputs into water exceed the quantities emitted to the atmosphere. However, the largest quantities of trace metals are discharged to the terrestrial environment. So far, the Pb budget seems to be the most accurate owing to a large body of information available on this element. The largest emissions of Pb were estimated for gasoline combustion, contributing about two thirds of the total emissions to the atmosphere. Emissions from nonferrous metal production contributed about one quarter. Emissions from the European and Asian sources contributed each about one third of the global emissions, followed by emissions from sources in North America. A spatial distribution of the global Pb emissions is presented within a 1 × 1° grid system.Key words: trace metals, lead, global emission, emission map.

ISSN:1208-6053    

DOI:10.1139/a95-006

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Incremental growth layers occur in the hard structures of many types of organisms (tree xylem, mollusc shells, vertebrate teeth, otoliths, scales, etc.). Microprobes have previously shown that these layers contain archival information about an organism's chemical environment. However, trace elements, including metals, are generally undetectable with these instruments. A relatively new technique, laser ablation – inductively coupled plasma – mass spectrometry (LA-ICP-MS) promises multielement analytical capability with extremely low detection limits (conservatively, <1 ppm), combined with very fine spatial resolution (down to 30–100 μm beam diameter). Fish otoliths and vertebrate tooth cement and dentin offer the greatest potential for retrieving element archival information, because they are not subject to resorption, and reflect the organism's exposure to or accumulation of trace elements from the ambient environment. Other structures are less promising, because they exhibit element mobility between growth layers (tree rings), or are subject to metabolic turnover and resorption (scales, bones, shells). While the LA-ICP-MS technique is novel in the biological sciences, the few studies available indicate that reproducible, year-by-year data on metal accumulation or exposure will probably be retrievable from many types of incremental structures. The main problem currently is the lack of solid standard reference materials which match the physicochemical properties of hard biological tissues.Key words: laser ablation, mass spectrometry, trace metals, environmental pollution, calcified tissues.

ISSN:1208-6053    

DOI:10.1139/a95-007

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Polychlorinated biphenyls (PCBs) have been recognized for over 25 years as global environmental contaminants. However, many PCB congeners may be relatively harmless, while a small group of PCB congeners are highly toxic to biota. The toxic coplanar PCB congeners are chlorinated atmetapositions and at one or none of theorthopositions on the biphenyl ring, thus resembling 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in molecular configuration. In vitro and in vivo toxicity tests with rodents, fish, and birds have shown that the coplanar PCB congener 126 is almost as toxic as TCDD. Several coplanar PCBs (e.g., 77, 126, 105, 118) are present in biota at parts per billion concentrations, which is orders of magnitude higher than concentrations of TCDD. Thus, coplanar PCBs may account for over 95% of the dioxinlike toxic activity affecting biota, such as fish-eating birds in the Great Lakes. There is some evidence that the toxicokinetics of coplanar PCBs in organisms differs from that of other PCB homologues. If coplanar PCBs are more persistent than their homologues, they could become enriched in biota as they pass up through the food chain (i.e., trophic enrichment), or as overall PCB levels decline with time (i.e., temporal enrichment). Overall, the available data do not support the concept of trophic or temporal enrichment in the environment.Key words: polychlorinated biphenyls, coplanar, toxic equivalents, kinetics, mixed function oxidase, 7-ethoxyresorufin-O-deethylase.

ISSN:1208-6053    

DOI:10.1139/a95-008

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Tropical deforestation often produces landscapes characterized by isolated patches of forest habitat surrounded by pasture, agriculture, or regrowth vegetation. Both the size and the distribution of these forest patches may influence the long-term persistence of faunal species. There is, therefore, a pressing need to understand faunal responses to patterns of forest fragmentation in tropical systems. The Biological Dynamics of Forest Fragments Project (BDFFP) provides a wealth of autecological information and spatially explicit data describing habitat use and movement of fauna between Amazonian forest fragments. Using data from the BDFFP and other studies in the Amazon Basin, this paper reviews the information available on tropical insects, frogs, birds, primates, and other mammals that can be used to identify and classify species most at risk for extirpation in fragmented forests.Key words: Amazonia, habitat fragmentation, rainforest, fauna, Biological Dynamics of Forest Fragmentation Project.

ISSN:1208-6053    

DOI:10.1139/a95-009

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Globally, arsenic introduced into the biosphere by human activities has greatly surpassed arsenic from natural sources, the supply of the element from these two sources being approximately 60 and 40%, respectively. However, numerous regions of the world have elevated concentrations of arsenic from natural sources. Arsenopyrite may contain up to 6000 μg∙g−1of arsenic and the weathering of such geological materials can increase the levels of arsenic in groundwater. Long-term consumption of groundwater containing elevated concentrations of arsenic has caused natural chronic arsenic intoxication in local populations in Taiwan, Mexico, Chile, Argentina, and other countries. An endemic disease commonly called blackfoot disease, which is also caused by arsenic in drinking water, was documented in Taiwan in 1963. For more than 80 years local populations had consumed well water with arsenic concentrations as high as 1829 μg∙L−1. The widespread geographical distribution of minerals with high arsenic content suggests that many new regions with natural arsenic contamination will be identified in the near future.Key words: arsenic, natural, cycling, chronic, contaminat

ISSN:1208-6053    

DOI:10.1139/a95-010

出版商:NRC Research Press    

年代:1995

数据来源: NRC