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The state of North Carolina's Department of Environment and Natural Resources (NCDENR) conducts routine water quality monitoring
throughout the state to assess the health of aquatic systems. The current study reports the results of a retrospective (1990–2000)
ecological risk assessment of six heavy metals (arsenic, cadmium, copper, lead, mercury, and zinc) in 17 North Carolina basins
that was conducted to estimate the risk of heavy metal toxicity to freshwater organisms and assess the sufficiency of NCDENR's
monitoring data to identify water-quality-related ecological threats. Acute and chronic ecotoxicological thresholds (ETs)
were calculated for each metal based upon the 10th percentile of species sensitivity distributions and were normalized for
water hardness. Statewide probabilities (expressed as percentages) of a random sample exceeding acute or chronic ETs among
the six metals ranged from 0.01% to 12.19% and 0.76% to 21.21%, respectively, with copper having the highest and arsenic and
mercury the lowest risk. Basin-specific probabilities varied significantly depending upon water hardness and presumably watershed
development. Although the majority of specific sites where data were collected were at low risk for metal toxicity, some specific
sites had a high probability of toxic events associated with one or more metals. Analytical detection limits for metals were
frequently higher than estimated chronic ET, limiting the ability to assess the risk of chronic toxicity in soft-water basins.
Results suggest risk-based criteria may be useful for assessing and validating the sufficiency of monitoring programs and
prioritizing management goals. 相似文献
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TERENCE PRESTON YORKS NEIL E. WEST RICHARD J. MUELLER STEVEN D. WARREN 《Environmental management》1997,21(1):121-131
/ An exhaustive search of the literature for foot and vehicle traffic impacts on vegetation has yielded more than 400 citations, two thirds of which held sufficient detail to be usefully distilled into a personal-computer data base. A total of 1444 individual observations involving 737 species that were trampled are included. Compromises were made in the depth of entry detail and to allow comparability among data. Inconsistent, generally short-term, experimental practices disallowed formal statistical analyses. Within those constraints, graminoids emerged with the highest mean resistance and resilience among life-forms. Climbers and cactoids ranked lowest in these categories. The herbaceous, typically broader-leaved (forb) life-form appeared most likely to suffer immediate losses. Shrubs and trees had the longest-lasting decreases in diversity following traffic impact. All life-forms had sensitive species. The greatest general species and individual plant losses take place in the first few passes by feet, wheels, or tracks. Plant and soil damage increases with the amount of weight and power applied. Greater soil moisture and/or deeper overstory shading magnify those impacts. Additional precepts may become apparent to data-base users through increased ease in making comparisons.KEY WORDS: Vegetation; Trampling; Vehicles; Traffic; Resistance; Resilience; Data base 相似文献
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Preston BL 《Environmental management》2002,29(3):311-323
Understanding toxicant effects at higher levels of biological organization continues to be a challenge in ecotoxicology and
ecological risk assessment. This is due in part to a tradition in ecotoxicology of considering the direct effects of toxicants
on a limited number of model test species. However, the indirect effects of toxicity may be a significant factor influencing
the manner in which ecosystem structure and function respond to anthropogenic stressors. Subsequently, failure to incorporate
indirect effects into risk assessment paradigms may be a significant source of uncertainty in risk estimates. The current
paper addresses the importance of indirect effects in an ecotoxicological context. Laboratory, mesocosm, and whole ecosystem
research into indirect effects is reviewed. The implications of indirect effects for ecological risk assessment and potential
areas of profitable future research are also discussed. 相似文献
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