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851.
本文通过对“九五”期间张家界市的生态环境质量进行回顾性分析评价,在掌握其区域自然特征和生态环境现状的基础上,运用环境科学的基本理论分析了张家界市环境质量变化原因和趋势,指出了张家界市存在的主要生态环境问题,并提出了若干对策来引导张家界市的生态环境建设,以实现其建设生态城市的宏伟目标. 相似文献
852.
Barbara Raffaelli Eija Leppälä Clément Chappuis Kristiina Wähälä 《Environmental Chemistry Letters》2006,4(1):1-9
Seven new dibenzylbutyrolactone and six new dibenzylbutanediol lignans were prepared to assist in the identification of a
number of potential mammalian metabolites of the endocrine disrupting plant lignans syringaresinol and medioresinol, present
in food. 相似文献
853.
Electronic tagging and remotely sensed oceanographic data were used to determine the oceanographic habitat use and preferences
of Atlantic bluefin tuna (Thunnus thynnus L.) exhibiting behaviors associated with breeding in the Gulf of Mexico (GOM). Oceanographic habitats used by 28 Atlantic
bluefin tuna exhibiting breeding behavior (259 days) were compared with available habitats in the GOM, using Monte Carlo tests
and discrete choice models. Habitat utilization and preference patterns for ten environmental parameters were quantified:
bathymetry, bathymetric gradient, SST, SST gradient, surface chlorophyll concentration, surface chlorophyll gradient, sea
surface height anomaly, eddy kinetic energy, surface wind speed, and surface current speed. Atlantic bluefin tuna exhibited
breeding behavior in the western GOM and the frontal zone of the Loop Current. Breeding areas used by the bluefin tuna were
significantly associated with bathymetry, SST, eddy kinetic energy, surface chlorophyll concentration, and surface wind speed,
with SST being the most important parameter. The bluefin tuna exhibited significant preference for areas with continental
slope waters (2,800–3,400 m), moderate SSTs (24–25 and 26–27°C), moderate eddy kinetic energy (251–355 cm2 s−2), low surface chlorophyll concentrations (0.10–0.16 mg m−3), and moderate wind speeds (6–7 and 9–9.5 m s−1). A resource selection function of the bluefin tuna in the GOM was estimated using a discrete choice model and was found
to be highly sensitive to SST. These habitat utilization and preference patterns exhibited by breeding bluefin tuna can be
used to develop habitat models and estimate the probable breeding areas of bluefin tuna in a dynamic environment. 相似文献
854.
Marco Barucca Francesca Azzini Giorgio Bavestrello Maria Assunta Biscotti Barbara Calcinai Adriana Canapa Carlo Cerrano Ettore Olmo 《Marine Biology》2007,151(2):529-535
A phylogenetic analysis of some bioeroding sponges of the family Clionaidae (Order Hadromerida) was performed to resolve some
taxonomic problems both at the specific and the supraspecific level using the D2 and D3 regions of 28S rDNA. Species belonging
to the genera Cliona, Cliothosa, Spheciospongia (fam. Clionaidae) and Diplastrella (fam. Spirastrellidae) from the Mediterranean Sea and Celebes Sea (Indonesia) were analysed. In the phylogenetic tree, the
species clustered on two main branches, one comprising Cliona celata, C. rhodensis, C. utricularis, and Cliothosa hancocki, and the other made up of C. viridis, C. nigricans, C. schmidti, C. jullieni, Spheciospongia solida and S. vagabunda. Above the species level, data do not support the separation of the genus Cliothosa from Cliona, while they do support the inclusion of some massive boring species, previously assigned to the genus Spirastrella, in the family Clionaidae. At the species level, data demonstrated the genetic identity of taxa C. viridis and C. nigricans, in spite of their considerable morphological differences. In contrast, the yellow species commonly attributed to C. celata are probably to be considered as a complex of sibling species with a number of distinct taxa present in the Mediterranean.
Data also showed the identity of the Mediterranean and Pacific populations of C. schmidti, suggesting the status of a Tethyan relict for this species. 相似文献
855.
The concentration of solubilized aluminium in soils and waters increases due to environmental influences. To obtain information on the types of Al species occuring under these conditions, aluminium chloride solutions were prepared in a wide range of concentrations (10?1–10?5 mol·l?1 Al) and basicity (OH/Al=0,5–2,5), respectively, and then structurally characterized using the ferron method. For the freshly prepared solutions, a decrease in the portion of monomeric Al species is observed, with an increasing OH/Al-ratio; the formation of polymeric cations decreases to lower OH/Al-ratios with diminishing concentration. The portion of tridecameric cations (Al13) decreases with diminishing concentration, but so called transition polymers occur in these solutions. The transition polymers are instable under ageing; by inreasing the ageing time, a disproportion of these cations into monomeric and polymeric species can be observed. At extremly low Al concentrations (10?5 mol·l?1 Al), a condensation of the transition polymers into polymeric species occurs, after only a short ageing. The influence of admixtures of Mg2+-and Ca2+-ions, respectively, on the specification of the Al cations are only observed after longer ageing times; in this case, the formation of polymeric Al species is forced. The polymeric Al species therefore, seem to be especially preferred alongside the monomeric ones under biologically relevant concentrations. 相似文献
856.
857.
858.
This paper summarizes the results of a primarily qualitative (with certain quantitative elements) socio-ecological study on three Greek islands of the Aegean Archipelago to characterize fire science and policy at regional and local levels, and perceptions of fire risk. Among the most important factors influencing dynamics of fire regimes on the islands are changing land use patterns and practices, and changes in climate and fuel conditions. While use of scientific information is not widespread, there are individuals in all three islands who regularly consult scientific sources. Although fire policy is largely controlled at the national and European Union levels, local activity also occurs, most notably through the volunteer fire fighting organizations, interactions with local officials, and public education efforts. However, though seen as important, significant lack of financial support and resources exist to support prevention and pre-suppression programs. Prevention of fires on the islands, including the use of prescribed burning, is relatively inadequate, and while an intense interest in preventing the loss of communities and ecosystems is frequently encountered, public participation in fire prevention remains limited. The findings suggest that relying on local knowledge, in combination with fire managers’ decision-making abilities, could improve fire management options and reduce wildfire suppression costs and ecological disasters. 相似文献
859.
860.
Effective manure management to efficiently utilize organic wastes without causing environmental degradation requires a clear understanding of the transformation of P forms from diet to manure. Thus, the objective of this study was to establish quantitative relationships between P forms in diets, feces, and manures collected from U.S. Northeastern and Mid-Atlantic commercial dairy farms. Total P in diets ranged from 3.6 to 5.3 g kg(-1) dry matter, while the feces had higher P than diets (5.7-9.5 g kg(-1)) and manures had lower P (2.5-8.9 g kg(-1)) than feces. The farms with total dietary P of 4.8 to 5.3 g P kg(-1) had twofold higher concentrations of phytic acid (1647-2300 mg P kg(-1)) than farms with 3.6 to 4.0 g dietary P kg(-1) (844-1100 mg P kg(-1)). Much of the phytic acid in diets was converted to inorganic orthophosphate in the rumen as indicated by a reduction in phytic acid percentage from diets (32%) to feces (18%). The proportion of orthophosphate diesters (phospholipids, deoxyribonucleic acid [DNA]) was twice as high in feces (6.2-10%) as diets (2.4-5.3%) suggesting the excretion of microbial residues in feces. Phosphonates (aminoethyl phosphonates and phosphonolipids) were not seen in diets but were detected in feces and persisted in manures, which suggests a microbial origin. These organic compounds (phytic acid, phospholipids, DNA) were decomposed on storage of feces in slurry pits, increasing orthophosphate in manures by 9 to 12% of total P. These results suggest that reducing dietary P and typically storing feces in dairy farms will result in manure with similar chemical forms (primarily orthophosphate: 63-77%) that will be land applied. Thus, both the reduction of dietary P and storage of manure on farm are important for controlling solubility and bioavailability of P forms in soils and waters. 相似文献