大气-水体系统中PAR传输模式及湖泊初级生产力   总被引：2，自引：2，他引：2       下载免费PDF全文

蔡启铭  杨平 《水科学进展》1993,4(3):171-178

给出了一种大气-水体系统中PAR的传输模式,并利用太湖的气象和实测悬浮粒资料计算水体中PAR的时空变化.模式中考虑了大气的气溶胶、臭氧、水汽和CO₂的效应以及水面风浪、水中黄质、悬浮粒和浮游藻类的多次散射和吸收过程.最后,利用生物-光模式,计算了太湖的初级生产力.结果基本上能反映水中初级生产力随水深的变化趋势.  相似文献   

气候变化对植物气候生产力的影响   总被引：37，自引：0，他引：37  

高素华  潘亚茹  郭建平 《气象》1994,20(1):30-33

分析了我国大体分布均匀的３５０个站点近４０年植物气候生产力的时空变化及５０、６０、７０、８０年代距平场变化，并讨论了“暖干型“、“暖湿型“、“冷湿型“、“冷干型“气候对植物气候生产力的影响。  相似文献   

CT引导下原发性肝癌光动力学治疗效果     

陈静  王彩霞 《CT理论与应用研究》1994,3(2):18-20

本文介绍了在ＣＴ引导下，利用激光对原发性肝癌局部进行光动力学疗法（以下简称ＰＤＴ），治疗半月后，进行ＣＴ复查，所有病人肿块中心均出现大小不等的液化坏死区，液化坏死区最大直径３．７ｃｍ，ＣＴ值下降７—４９ＨＵ，经组织学检查治疗区，表明细胞膜严重受损，并可见大量坏死组织，经ＰＤＴ治疗后的病人生存超过半年者达９２．３％，所有随访病例均未发现肿块增大及其它部位转移，有肝区疼痛者，治疗后疼痛消失，同时食欲明显增加，体重有所增长。  相似文献   

黑龙江省尚志地区新生代钾质玄武岩研究     

刘贤华 《岩石学报》1990,6(3):53-64

尚志中新世富碱的钾质系列玄武岩为白榴霞石岩、橄榄霞石岩、霞石碧玄岩和橄榄碧玄岩。岩石中似长石矿物大量出现,霞石和白榴石可以共存。稀土元素和大离子不相容元素的特征表明形成白榴霞石岩、橄榄霞石岩、霞石岩碧玄岩和橄榄碧玄岩的地幔熔融程度越来越高。主元素和微量元素的模拟计算表明,霞石岩岩浆为上地幔岩2～4％的熔融,碧玄岩为上地幔橄榄岩5～8％的部分熔融;这些岩浆形成时的温压条件为:霞石岩的T=1410～1430℃,P=22～23×10~8Pa;碧玄岩的T=1380～1430℃,P=20～23.5×10~8Pa。  相似文献   

Nutrient and Plankton Dynamics in the NE and NW Gyres of the Subarctic Pacific Ocean     

Paul J. Harrison  Frank A. Whitney  Atsushi Tsuda  Hiroaki Saito  Kazuaki Tadokoro 《Journal of Oceanography》2004,60(1):93-117

The western subarctic gyre (WSG) and the eastern Alaska Grye (AG) on each side of the subarctic North Pacific, have many similarities. In both gyres, macronutrients are generally high and chl is low, and hence both gyres are High Nitrate, Low Chlorophyll (HNLC) regions. Despite the general similarities between these two gyres, there are many important differences. The time series station established at Stn KNOT on the southwest edge of the WSG and two in situ mesoscale iron enrichment experiments at each of the gyres has provided more information on iron concentrations, the dual role of iron and silicate limitation and seasonal cycles in the gyres. There is more seasonality in many parameters at Stn KNOT than at Stn P. There is an increase in Chl and primary productivity at Stn KNOT in May followed by increased iron limitation in summer. Low DIC:NO₃ ratios and high Si:NO₃ ratios in the WSG, indicate lower calcification and higher diatom production than at Stn P. The sources of iron for these areas are still not clear, but horizontal transport of iron rich coastal water and vertical transport could be important sources at certain times of the year in addition to dust input. Satellite images show that chl-rich coastal waters occasionally extend to the vicinity of Stn KNOT and therefore Stn KNOT may not always represent conditions in the main part of the WSG. This review focuses mainly on a comparison of Stn KNOT and Stn P, two time series stations on the edge of two very large gyres. At present, we have a limited understanding of the temporal and spatial variability within each of these large gyres. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Baja California's Biological Transition Zones: Refuges for the California Sardine     

Daniel Lluch-Belda  Daniel B. Lluch-Cota  Salvador E. Lluch-Cota 《Journal of Oceanography》2003,59(4):503-513

The information on the transitional areas between the temperate and tropical domains at the southern extent of the California Current System is reviewed and described, particularly searching for the relative isolation or interchange between the western coast of the Baja California peninsula and the Gulf of California, as well as mechanisms that permit the existence of sizeable stocks of California sardine. Biological Action Centers that have high productivity throughout the year, as opposed to the rest of the coastal area, are found in both the western coast of the peninsula at the Sebastián Vizcaíno—Punta Eugenia region and in the Ballenas Channel inside the gulf; these features support large biomasses of sardine throughout the full year and serve as long term refuges during adverse periods. The role of the Sebastián Vizcaino sardine stock as the primary group for expansion is examined. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Bio-optical signatures and biogeochemistry from intense upwelling and relaxation in coastal California     

Raphael M. Kudela  Newell Garfield  Kenneth W. Bruland 《Deep Sea Research Part II: Topical Studies in Oceanography》2006,53(25-26):2999

The NSF-sponsored Coastal Ocean Processes Wind Events and Shelf Transport (WEST) experiment investigates the interplay between wind-driven transport and shelf productivity; while eastern boundary shelves are characterized by high productivity due to upward fluxes of nutrients into the euphotic zone, wind forcing also represents negative physical and biological controls via offshore transport and deep (light-limiting) mixing of primary producers. Although this interaction has been well documented for eastern boundary systems generally and for California specifically, one of the primary goals of WEST was to characterize more fully the interplay between positive and negative effects of wind stress, which result in the consistently elevated biological productivity in these shelf regions. During 3 month-long summer cruises (2000–2002) we observed extremes in upwelling/relaxation, using both in situ instrumentation and remotely sensed data. Relationships between optical and physical properties were examined, with emphasis on biogeochemical implications. During 2000, the WEST region was optically dominated by phytoplankton and covarying constituents. During 2001 and 2002, periods of more intense upwelling favorable winds, we observed a transition to optical properties dominated by detrital and inorganic materials. In all years, the continental shelf break provided a natural boundary between optically distinct shelf and open ocean waters. During 2002, we obtained discrete trace-metal measurements of particulate iron and aluminum; we develop a bio-optical proxy for acetic-acid leachable iron from backscatter and fluorescence, and demonstrate that particulate iron is not well correlated to traditional upwelling proxies such as macronutrients, temperature, and salinity. We conclude that the shelf break between ca. 100 and 200 m water depth serves as a natural break point between coastal and oceanic water masses in this region, and that the elevated biomass and productivity associated with this eastern boundary current regime is dominated by these iron rich, shallow shelf waters.  相似文献   

改善港湾初级生产力遥感探测方法的探讨     

陈晓翔  李铁芳  英登耿 《热带海洋学报》1995,(4)

从遥感光谱信号在海水中的传播特点出发，分析了目前应用遥感方法探测港湾初级生产力精度不高的原因；并从港湾初级生产力的生存条件着手，指出水交换状态是一种有效的可监测因素，可将其引入到港湾初级生产力的遥感探测模型中。提出了互补性参数的引入可能是模型改善的原因。通过作者在大亚湾的初步试验表明；水交换状态参数的引用，模型的误差从６．５％降为０．２６％，精度大大提高，从而证明了该方法的可行性和有效性。  相似文献   

Experimental evidence of habitat provision by aggregations of Riftia pachyptila at hydrothermal vents on the East Pacific Rise     

Breea Govenar  & Charles R. Fisher 《Marine Ecology》2007,28(1):3-14

Habitat created or modified by the physical architecture of large or spatially dominant species plays an important role in structuring communities in a variety of terrestrial, aquatic, and marine habitats. At hydrothermal vents, the giant tubeworm Riftia pachyptila forms large and dense aggregations in a spatially and temporally variable environment. The density and diversity of smaller invertebrates is higher in association with aggregations of R. pachyptila than on the surrounding basalt rock seafloor. Artificial substrata designed to mimic R. pachyptila aggregations were deployed along a gradient of productivity to test the hypothesis that high local species diversity is maintained by the provision of complex physical structure in areas of diffuse hydrothermal flow. After 1 year, species assemblages were compared among artificial aggregations in low‐, intermediate‐, and high‐productivity zones and compared to natural aggregations of R. pachyptila from the same site. Hydrothermal vent fauna colonized every artificial aggregation, and both epifaunal density and species richness were highest in areas of high chemosynthetic primary production. The species richness was also similar between natural aggregations of R. pachyptila and artificial aggregations in intermediate‐ and high‐productivity zones, suggesting that complex physical structure alone can support local species diversity in areas of chemosynthetic primary production. Differences in the community composition between natural and artificial aggregations reflect the variability in microhabitat conditions and biological interactions associated with hydrothermal fluid flux at low‐temperature hydrothermal vents. Moreover, these local ecological factors may further contribute to the maintenance of regional species diversity in hydrothermal vent communities on the East Pacific Rise.  相似文献   

Distribution of seabirds in the northern Gulf of Mexico in relation to mesoscale features: initial observations   总被引：1，自引：0，他引：1  

Ribic  Christine A.; Davis  Randall; Hess  Nancy; Peake  Dwight 《ICES Journal of Marine Science》1997,54(4):545-551

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