排序方式： 共有20条查询结果，搜索用时 421 毫秒
11.
Commercially cultured strings of mussels were transplanted to five sites along the Ninety Mile Beach, Victoria, Australia, to assess the operational impact of an ocean outfall on bioaccumulation of dioxins and furans. The monitored outfall discharges a complex effluent containing secondary treated domestic, industrial and pulp and paper mill effluent as well as oil and gas production waste waters. Mussels were deployed twice yearly for a period of 3 years, with both pre-discharge and post-discharge data collected. Mussel tissue furan concentrations were generally below detection limits, whereas dioxins were detected in all tissue samples. Tissue dioxin congener profiles were similar to unpolluted seawater, with penta-, hepta- and octa-substituted dioxin congeners being detected in the highest concentrations. Tissue concentrations of dioxins and furans in deployed mussels provided no evidence to suggest that bioaccumulation of dioxins discharged from the ocean outfall was occurring. 相似文献
12.
Louisa S. Evans 《Ocean & Coastal Management》2010,53(4):180-191
Proponents of integrated, collaborative, and adaptive governance advocate the inclusion of a diversity of stakeholders and their knowledge and values in governance processes. This paper examines knowledge interactions at different scales of decision-making within two marine social-ecological systems in southern Kenya. Ecological knowledge systems are shown to be diverse and fluid even within broad conceptual classifications. Knowledge interactions at the local level are mediated by socio-cultural, institutional, and historical factors, whilst knowledge integration within district to national levels is primarily structured by institutional factors linked to centralised decision-making. In policy arenas, knowledge bounded to the marine environment is subjugated by knowledge dealing with terrestrial parks, inland fisheries, and wildlife tourism. 相似文献
13.
14.
Didier Hauglustaine Louisa Emmons Mike Newchurch Guy Brasseur Toshinori Takao Kouji Matsubara James Johnson Brian Ridley Jeff Stith James Dye 《Journal of Atmospheric Chemistry》2001,38(3):277-294
A series of ozone transects measured each year from 1987 to 1990 over thewestern Pacific and eastern Indian oceans between mid-November andmid-Decembershows a prominent ozone maximum reaching 50–80 ppbv between 5 and 10 kmin the 20° S–40° S latitude band. This maximum contrasts with ozonemixing ratios lower than20 ppbv measured at the same altitudes in equatorial regions. Analyses witha globalchemical transport model suggest that these elevated ozone values are part ofa large-scale tropospheric ozone plume extending from Africa to the western Pacific acrosstheIndian ocean. These plumes occur several months after the peak in biomassburninginfluence and during a period of high lightning activity in the SouthernHemispheretropical belt. The composition and geographical extent of these plumes aresimilar to theozone layers previously encountered during the biomass burning season in thisregion.Our model results suggest that production of nitrogen oxides from lightningstrokes sustains the NOx (= NO+NO2) levels and the ozonephotochemical productionrequired in the upper troposphere to form these persistent elevated ozonelayers emanating from biomass burning regions. 相似文献
15.
Measuring the effect of overgrazing in the Sonoran Desert 总被引：4，自引：0，他引：4
Nevin A. Bryant Lee F. Johnson Anthony J. Brazel Robert C. Balling Charles F. Hutchinson Louisa R. Beck 《Climatic change》1990,17(2-3):243-264
Long term overgrazing in Mexico has caused a sharp discontinuity in vegetative cover along the international border in the semi-arid Sonoran Desert. The United States side, protected from overgrazing by the Taylor Act since 1934, exhibits longer, more plentiful grasses and less bare soil than adjoining Mexican lands. Satellite- and ground-based datasets were used in a multi-scale examination of the differential radiative and reflective characteristics of the two regimes. The more exposed Mexican landscape dries more rapidly than the United States following summer convective precipitation. After about three days, depletion of soil moisture evokes a period of higher surface and air temperatures in Mexico. Good correspondence was found between remote and in situ measures of surface temperature and biomass. 相似文献
16.
To understand the subtle institutional conditions that underlie marine governance, beyond broad conceptualisations of property rights or pre-defined institutional designs, it is necessary to situate governance structures and human interactions within their historical and current social and political context. A two-tiered stakeholder analysis was developed to facilitate this. This analytical tool illuminates divergent perspectives between actors in two marine social-ecological systems in Southern Kenya. Investigating these differences emphasises the variety of historical contexts, social geographies, and current power relations in which different groups are situated. These historical and contextual factors mediate how groups perceive and respond to governance. They, therefore, have important implications for how institutions function. 相似文献
17.
18.
Pedro Fidelman Louisa EvansMichael Fabinyi Simon FoaleJosh Cinner Franciska Rosen 《Marine Policy》2012,36(1):42-53
Environment and development agendas are increasingly being characterised by regional-scale initiatives. This trend is in part motivated by recognition of the need to account for global drivers of change (e.g., climate change, migration, and globalisation), the aspirations of achieving large-scale ecological goals (such as maintaining ecosystem processes), and reconciling potentially conflicting priorities in multi-use planning. However, regional-scale governance is challenging and there is little theoretical guidance or empirical evidence to suggest how it can be achieved. This paper uses the Institutional Analysis and Development framework to highlight the diverse contextual factors that challenge governance of a large-scale marine common, using an example of the Coral Triangle Initiative. The analysis points to the need for a critical, reflexive approach to the Coral Triangle Initiative if it is to effectively navigate diverse contexts and reconcile multiple objectives in the region. Recognising the heterogeneous, multi-scale and interlinked nature of large-scale marine systems is critical. Coping with contextual complexity will require innovative approaches that strive to be inclusive of varied perspectives and actors, enable and support effective collective-choice arrangements at lower levels of organisation, and organise and link diverse institutional arrangements at multiple scales. Large-scale marine governance will also involve a great deal of experimentation and regular adjustments to governance arrangements to account for the dynamic nature of regional commons. 相似文献
19.
Seismic attributes, such as P- and S-wave velocity, Poisson’s ratio, and acoustic impedances, all generally can be used for
distinguishing different rock types. The non-uniqueness can be largely reduced using Lamé impedances instead of acoustic impedances
as additional constraints. We have followed this method to constitute a petrologic composition model of the upper crust in
the Bohai Bay basin, China. We briefly review the seismic parameters used for discrimination of rock types and focus our attention
on the sensitivity of different combinations of parameters to determine the composition of materials. Corrections for pressure
and temperature are performed in order to compare elastic wave velocities and densities measured at room temperature and surface
pressure in laboratory with those for representative rock parameters. In a second step, we find the rock classes in the tested
area by contrasting known data to laboratory measurements on a variety of rock samples extracted in the area. The basic field
data are P-wave velocity values collected along a seismic profile conducted in the Bozhong Depression. The different rock
types belonging to a particular rock class are finally constrained by the seismic velocities, Poisson’s ratio, density, acoustic
impedance, and Lamé impedance related to the topmost 10 km of the Bohai Bay crust. 相似文献
20.
许多地震属性,比如地震的纵横波速度,泊松比,声波阻抗,都能用来区分不同的岩石类型,利用拉梅阻抗作为进一步的约束来代替声波阻抗能更好的降低结果的非唯一性。我们用这种方法构建了渤海湾地区一条剖面的岩石成分模型。我们简要介绍了区分岩石类型的地震参数,重点在于不同的参数组合对于分辨岩石类型的敏感性。为了与室温常压条件下测得的有代表性的岩石的地震波速度和密度进行对比,我们首先需要做温度和压力的校正。接着,我们需要用已知资料和实验测得的各种岩石样品做对比,来确定研究区的岩石类型。我们收集了渤中凹陷一条剖面的纵波速度资料。该剖面10km深范围内的属于同种岩石类型的不同岩石最终通过地震波速度、泊松比、密度、声波阻抗、以及拉梅阻抗综合约束。 相似文献