排序方式： 共有3条查询结果，搜索用时 0 毫秒
1
1.
Issues in sediment toxicity and ecological risk assessment 总被引：8，自引：0，他引：8
This paper is based on a facilitated Workshop and Roundtable Discussion of key issues in sediment toxicology and ecological risk assessment (ERA) as applied to sediments that was held at the Conference on Dredged Material Management: Options and Environmental Considerations. The issues addressed included how toxicity is defined and perceived, how it is measured, and how it should be used within the context of ERA to support management decisions. The following conclusions were reached regarding scientific considerations of these issues. Toxicity is a measure of hazard and not a risk per se. Thus, toxicity testing is a means but not the end to understand risks of sediments. Toxicity testing cannot presently be replaced by chemical analyses to define hazard. Toxicity test organisms need to be appropriate to the problem being addressed, and the results put into context relative to both reference and baseline comparisons to understand hazard. Use of toxicity tests in sediment ERAs requires appropriate endpoints and risk hypotheses, considering ecological not just statistical significance, and recognizing that hazard does not equate to risk. Toxicity should be linked to population and community response to support decision-making, assessing possible genotypic adaptations that can influence risk estimates, and addressing uncertainty. Additionally, several key scientific issues were identified to improve future sediment ERAs, including the need to improve basic understanding of ecological mechanisms and processes, recognition of variability in the assessment process, and an improved focus and ability to assess risks to populations and communities. 相似文献
2.
J.W. Munns 《Marine and Petroleum Geology》1985,2(1):23-43
The Valhall Field is located within the Central Graben in the southern part of the Norwegian North Sea. The discovery well, 2/8-6, was drilled in 1975 and the field went on production in 1982. Production is currently 55 000 barrels of oil per day. The Valhall Field structure trends NW-SE and has an areal closure in excess of 60 000 acres. The hydrocarbon column measures ～200 m. The structure is located on an elongate anticlinal feature called the Lindesnes Ridge, which developed during Late Cenomanian to Oligocene tectonic movements. The geophysical evaluation of the field is complicated by the existence of a gas-charged Tertiary section which obscures the deeper seismic reflections. Vertical seismic profiles (VSPs) have been utilized in an attempt to resolve the reservoir configuration. Reservoirs occur both in the Tor Formation (Maastrichtian), and in the underlying Hod Formation (Turonian-Coniacian). The Tor Formation is represented by a largely allochthonous chalk facies which thins regionally to the southwest. A crestal graben is developed in which the Tor Formation is locally thick. Autochthonous chalks are characteristic of the Hod Formation. Primary porosity of the chalk varies between 36 to 50% on the crest of structure. Preservation of such high porosity is primarily due to formation overpressure inhibiting mechanical compaction of the chalk. The field contains paraffinic oil of 36 API gravity. It originated from the Upper Jurassic Kimmeridge Clay Formation, which is at peak oil generating capacity under the field at present day. 相似文献
3.
Programs for evaluating proposed discharges of dredged material into waters of the United States specify a tiered testing and evaluation protocol that includes performance of acute and chronic bioassays to assess toxicity of the dredged sediments. Although these evaluations reflect the toxicological risks associated with disposal activities to some degree, analysis activities are limited to the sediments of each dredging project separately. Cumulative risks to water column and benthic organisms at and near the designated disposal site are therefore difficult to assess. An alternate approach is to focus attention on the disposal site, with the goal of understanding more directly the risks of multiple disposal events to receiving ecosystems. Here we review current US toxicity testing and evaluation protocols, and describe an application of ecological risk assessment that allows consideration of the temporal and spatial components of risk to receiving aquatic ecosystems. When expanded to include other disposal options, this approach can provide the basis for holistic management of dredged material disposal. 相似文献
1