排序方式: 共有27条查询结果,搜索用时 281 毫秒
21.
河口水中矿物油分析的研究 总被引:1,自引:0,他引:1
紫外分光光度法在河口水中矿物油测定中,存在着标准油品的选择、水样萃取的乳化处理及河口水样测定方法选择等问题。提出了解决存在问题的可行方法,进一步完善测定方法。 相似文献
22.
Boesch Donald F. 《Journal of Coastal Conservation》1996,2(1):103-114
The influence of science in the recognition of the effects of landscape changes on coastal ecosystems and in the development
of effective policy for managing and restoring these ecosystems is examined through four case studies: Chesapeake Bay, San
Francisco Bay, the Mississippi Delta, and Florida Bay. These ecosystems have undergone major alterations as a result of changes
in the delivery of water, sediments and nutrients from their watersheds. Both science and management have been challenged
by the spatial, functional and temporal scale mismatches inherent in the watershed-coastal ecosystem relationship. Key factors
affecting the influence of science on management include (1) sustained scientific investigation, responsive to but not totally
defined by managers; (2) clear evidence of change, the scale of the change and the causes of the change; (3) consensus among
the scientific communities associated with various interests; (4) the development of models to guide management actions; (5)
identification of effective and feasible solutions to the problems. 相似文献
23.
Donald F. Boesch 《Journal of Coastal Conservation》1996,2(2):103-114
The influence of science in the recognition of the effects of landscape changes on coastal ecosystems and in the development
of effective policy for managing and restoring these ecosystems is examined through four case studies: Chesapeake Bay, San
Francisco Bay, the Mississippi Delta, and Florida Bay. These ecosystems have undergone major alterations as a result of changes
in the delivery of water, sediments and nutrients from their watersheds. Both science and management have been challenged
by the spatial, functional and temporal scale mismatches inherent in the watershed-coastal ecosystem relationship. Key factors
affecting the influence of science on management include (1) sustained scientific investigation, responsive to but not totally
defined by managers; (2) clear evidence of change, the scale of the change and the causes of the change; (3) consensus among
the scientific communities associated with various interests; (4) the development of models to guide management actions; (5)
identification of effective and feasible solutions to the problems. 相似文献
24.
Structural marsh management, using levees and water-control structures, is used in the coastal zone for many objectives, for
example, to reduce marsh loss, to enhance waterfowl habitat, to revegetate open-water areas, and to reduce saltwater intrusion.
The literature was evaluated to categorize structural marsh management and to determine some of its effects on fishes and
crustaceans. Structural marsh management had positive effects on standing stock of most resident organisms and negative effects
on marine-transient organisms. Emigration was negatively affected for both resident and marine-transient organisms. Techniques
such as opening structures at critical migration times, designing structures that offer the greatest management flexibility,
and using structures to create a flow-through system could reduce these impacts. More effort should be put into monitoring
managed areas to determine if the objectives are being met and to evaluate the effects on fishes and crustaceans. Although
frequent manipulation could reduce these impacts, the costs and problems incurred may outweigh the anticipated benefits. 相似文献
25.
J. A. González-Pérez J. R. de Andrés L. Clemente J. A. Martín F. J. González-Vila 《Environmental Chemistry Letters》2008,6(1):41-46
Here we show that heavy metal geoaccumulation is apparent in the Tinto and Odiel estuary and, at a lower magnitude, in off-shore
sediments. Values above probable effects level (PEL) are recorded for As, Cu, Hg, Pb and Zn in the Tinto and Odiel estuary,
for As and Hg in the associated off-shore sediments and for As in the Guadiana River. Significant correlations were found
between total organic carbon (TOC) and Cr, Cu, Ni and Zn in the Tinto and Odiel estuary, and Cr, Cu, Ni, Pb, Hg and As in
the Guadiana River. PCA analysis differentiated the three studied locations. 相似文献
26.
Measured monthly atmospheric depositional fluxes of cosmogenically produced 7Be ranged from 1 to 67 mBq/cm2 in Boston, Massachusetts between September 2000 and August 2007. These fluxes exhibited seasonality and supported a decay-corrected 7Be atmospheric depositional running inventory that ranged from 36 to 144 mBq/cm2. Annual 7Be deposition exhibited an increasing trend that may reflect a general decrease in solar activity and a general increase in precipitation over the 7-year sampling period. To investigate short-term sediment dynamics and accumulation patterns in the Neponset River estuary, we collected six sediment cores in July 2006 and measured 7Be sediment inventories ranging from 48 to 546 mBq/cm2 Comparisons of these sediment inventories with the 7Be running inventory from atmospheric deposition (101 mBq/cm2) at the time of core collection indicated a large degree of spatial heterogeneity in sediment accumulation patterns and its potential use as a tool for assessing the impacts of environmental restoration activities in estuarine environments. 相似文献
27.
Lisa M. Smith John M. Macauley Linda C. Harwell Cynthia A. Chancy 《Environmental management》2009,44(1):149-162
Water quality was assessed following Hurricane Katrina in the affected waters of Alabama, Mississippi, and Louisiana. Post-landfall
water quality was compared to pre-hurricane conditions using indicators assessed by EPA’s National Coastal Assessment program
and additional indicators of contaminants in water and pathogens. Water quality data collected after Hurricane Katrina suggest
that the coastal waters affected by the storm exhibited higher salinity and concentrations of chlorophyll a, dissolved inorganic phosphorus, and total suspended solids following the storm compared to the previous 5-year averages.
Higher bottom dissolved oxygen concentrations and light attenuation were also observed. Contaminant concentrations measured
in the water column were very low or undetectable, as were the presence of pathogens. Overall water quality did not significantly
differ from water quality assessed in the five years preceding the storm. Statistical analyses indicate that use of a probabilistic
survey design is appropriate for making pre-storm and post storm comparisons for water quality condition on an areal basis.
The information in this article has been funded wholly (or in part) by the U.S. Environmental Protection Agency. It has been
subjected to review by the National Health and Environmental Effects Research Laboratory and approved for publication. Approval
does not signify that the contents reflect the views of the Agency, nor does mention of trade names or commercial products
constitute endorsement or recommendation for use. This is contribution number 1280 from the Gulf Ecology Division. 相似文献