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1.
The anthropogenic contribution of trace metals to settling particulate matter (SPM) and surficial sediments was determined on the high-energy continental shelf adjacent to Sydney, Australia. Settling particulate matter and surficial sediment was collected in the vicinity of a major sewage outfall and at five control sites on the middle shelf (80-100 m water depth). Sediment traps were deployed on 10 occasions for up to 2 weeks during the summer and winter of 1995 and SPM was analyzed for Ag, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn. Cobalt, Fe, Mn and Ni act conservatively in SPM and in sediments regionally and are used as normalizing elements to determine anthropogenic enrichment. Surficial sediments and SPM are enriched in Ag, Cr, Cu, Pb and Zn near a major ocean outfall and at four of the five control sites, although sewage particles contribute < 5% of trace metals in the total sample. Silver is the most sensitive trace metal tracer for establishing the presence of sewage particulate matter. Sewage particulate matter flux near the outfall was estimated using a two end-member mixing model and is below 0.5 g m(-2) day(-1) during all deployment periods. The mean sewage particulate matter flux at sampling locations 30 km and 60 km north of the outfall are <0.13 g m(-2) day(-1) and <0.01 g m(-2) day(-1), respectively, indicating an efficient dispersal of anthropogenic material on this high energy continental shelf. 相似文献
2.
Bioaccumulation of Cd, Co, Cu, Ni, Pb and Zn in Antarctic gammaridean amphipod collectives, Orchomene plebs (Hurley, 1965), was investigated during a cruise of RV "Polarstern" to the Wedell Sea. With the sole exception of Cd the organisms accumulated metals during exposure and depurated them in uncontaminated seawater. Four independent toxicokinetic experiments and one field study were modelled simultaneously to calculate the following size-dependent bioconcentration factors for organisms with body length 10 mm (BCF(10 mm)): 130 (Co), 4030 (Cu), 190 (Ni), 2900 (Pb), and 5210 (Zn). On the time scale of our experiments the data suggest an increased metal uptake by previously exposed test organisms. The collectives investigated may be regarded as potentially suitable biomonitors for Co, Cu, Ni, Pb and Zn but not for Cd. An approach to evaluate the sensitivity of Orchomene plebs as a biomonitor of waterborne metals in the field indicates minimal increments of the ambient exposure concentrations of 0.01 microg Co l(-1), 0.2 microg Cu l(-1), 0.4 microg Ni l(-1), 0.6 microg Pb l(-1) and 0.3 microg Zn l(-1). 相似文献
3.
Dowty RA Shaffer GP Hester MW Childers GW Campo FM Greene MC 《Marine environmental research》2001,52(3):195-211
Research was conducted to assess the impact of oiling on fresh-marsh plant communities and to test the efficacy of techniques that may be used to enhance the bioremediation of crude oil spills in these environments while minimizing secondary anthropogenic impacts. To emulate field conditions, a mesocosm facility was used that houses 120 mesocosm vessels, each of 200-1 capacity. A five-way factorial treatment arrangement was used that included two substrates (inorganic, organic), two nutrient regimes (fertilized, not fertilized), two aeration levels (substrate aeration, no aeration), three oiling concentrations (0-, 5-, 10-1 m(-2) of South Louisiana Sweet Crude oil), and four vascular plant species (Alternanthera philoxeroides, Panicum hemitomon, Phragmites australis, Sagittaria lancifolia, and an unplanted control). Under the 5- and 10-1 m(-2) oiling concentrations, S. lancifolia displayed a short-term response of increased productivity, whereas P. hemitomon had the highest biomass production and photosynthetic rates at the end of the 18-month experiment. Overall plant growth and productivity, as well as oil degradation, were significantly higher in the inorganic substrate, indicating that biodegradation of oil spills in organic substrates may require a longer time period. Time-released fertilizer also stimulated plant productivity and resulted in higher soil respiratory quotients, suggestive of greater microbial activity, particularly in aerated mesocosms. The amount of oil remaining after 18 months was lowest in aerated and fertilized mesocosms containing either P. hemitomon or S. lancifolia and a substrate of low organic matter content. 相似文献
4.
利用MapObjects进行地理信息系统二次开发建立的地名更新维护应用系统,哥以实现地理空间数据库(Geodatabase)要素类的访问和操作,在实现复杂要素通用GIS编辑功能的同时,利用ArcSDE还可以实现多用户网络化操作和管理,降低了开发成本. 相似文献
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借助地面模型进行航空像片GIS正射投影数字化 总被引:1,自引:0,他引:1
为更新地理信息系统的数据库,需对单张原始航片数字化的空间数据进行解析改正。用数字地形数据和适宜的水平控制基础可编制共线改正模型。用这种像片数字化方法可在没有摄影测量设备和数字化仪工作站情况下更新空间数据库。数据录入人员不需专门的摄影测量训练。对所测量的地面目标的测试表明,像片数字化法的精度(5.5±3mm)超过了用现有的野外数据输入方法所达到的精度。野外工作人员拥有数据的所有权并能控制更新过程。该 相似文献
7.
随着专题地图的广泛应用,统计地图起着越来越重要的作用。分区统计图表的符号设计是编制统计地图的关键。国内外许多学者在自动绘制统计图符号方面做了大量工作,对各种符号进行了归类,建立了点状符 相似文献
8.
城市综合地理信息系统的研制方法及在北京市地下管网图形数据库系统中... 总被引:2,自引:0,他引:2
本文论述了城市综合地理信息系统的目标、功能、内容。在ARC/INFO基础上,提出了城市综合地理信息系统的研制方法。北京市地下管网图形数据库系统的研制表明,这种方法是可行的。 相似文献
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图形编辑是GIS中数据录入、更新及图形输出时的重要环节。本文阐述了地图数据库下图形编辑的原理、方法,MDBGES的构成和功能,并分析了MDBGES的试验结果,按照用户应用程序与DBMS的关系,提出了库函数的建立及其分类方案,以及一整套与地图数据库接口函数的原型。在用户与DBMS的接口规范化方面作了有益探索。此外,本文探讨了符号图形编辑的两种设想。 相似文献