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Mario Hoppema Eberhard Fahrbach Michel H. C. Stoll Hein J. W. de Baar 《Journal of Marine Systems》1999,19(4):1935
Data from two cruises, one in April/May 1996 and one in December/January 1993, covering the same wide area in the offshore Weddell Sea, were used to derive the annual extent of entrainment and the capacity of the biological pump. The former property was obtained with the help of dissolved oxygen data, whereas the latter was approximated with nutrients. Especially the data from April/May, representing the initial state of the winter surface layer, were crucial to assess the annual extent of these processes. The results were applied to our carbon dioxide data. The annual increase of the Total CO2 (TCO2) concentration in the surface layer due to vertical transport amounts to 16.3 μmol kg−1. An entrainment rate of deep water in the surface layer amounting to 35±10 m yr−1 was deduced. The compensating, biologically mediated TCO2 reduction was calculated to be larger than the TCO2 increase due to vertical transport. Since the balance of these two processes determines whether the Weddell Sea is a source or a sink of CO2, this indicates that the Weddell Sea, albeit upwelling area, is definitely a sink for atmospheric CO2 on an annual basis. This conclusion is further supported by contemplations that the biological drawdown of CO2 in the Weddell Sea as a whole is probably underestimated by our calculations. The new production for the Weddell Sea on a per unit area basis was found to be much higher than that for the Antarctic Ocean, when the latter value is being obtained by traditional biological methods. On the other hand, the CO2 uptake by the Weddell Sea on a per unit area basis is somewhat smaller than the CO2 uptake by the world ocean. 相似文献
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碳纤维加固桥梁新技术 总被引:1,自引:2,他引:1
碳纤维以其具有极好的比强度和比刚度,优秀的耐腐蚀性已广泛用于混凝土结构的粘贴加固工程,并已逐步形成了碳纤维加固混凝土桥梁的新技术。就这一新技术的材料特性、施工方法等进行了探讨。 相似文献
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复叠式制冷系统具有良好的应用前景,利用自然工质CO_2、NH_3做制冷剂使系统有着很大的优势;对影响复叠制冷循环性能系数的几个因素进行热力学分析,并指出此系统的特点。 相似文献
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在“双碳”战略背景下提出一种新型装配式空心钢管混凝土支撑。为了研究其受力性能并将其应用于地下车站深基坑工程中,设计并加工2个足尺寸空心钢管混凝土支撑试件,完成轴压加载试验,2个支撑试件最后均发生了混凝土压碎破坏,同时得到试件承载力指标。采用ABAQUS有限元软件建立空心钢管混凝土支撑的数值模型,开展考虑材料非线性和几何非线性的有限元分析,所得数值分析结果与试验结果吻合良好,验证了有限元模型的准确性。试验和有限元结果充分表明所提出的新型装配式空心钢管混凝土支撑满足常规工程设计要求,已成功应用于“汤马区间”2号风井工程,并与现浇钢筋混凝土支撑和装配式钢管支撑进行比较分析,结果表明该新型支撑可以显著降低碳排放量和经济成本。 相似文献
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堤防结构定期维修加固是预防安全隐患,确保堤防设施安全运行的重要手段。结合双向碳纤维网格在上海堤防设施维修加固工程的首次应用实例,介绍了碳纤维网格加固方法,分析了碳纤维网格加固系统在堤防维修加固工程中的适用性和先进性,探究了碳纤维网格受弯加固原理,推导了受弯承载力计算公式并验证了公式的正确性,为类似堤防维修加固工程提供参考和借鉴。 相似文献
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Car ownership in China is expected to grow dramatically in the coming decades. If growing personal vehicle demand is met with conventional cars, the increase in greenhouse gas emissions will be substantial. One way to mitigate carbon dioxide (CO2) emissions from passenger travel is to meet growing demand for cars with alternative vehicles such as hybrid- and battery-electric vehicles (HEVs and BEVs). Our study examines the cost-effectiveness of transitioning from conventional cars to HEVs and BEVs, by calculating their marginal abatement cost (MAC) of carbon in the long-run. We find that transitioning from conventional to hybrid and battery electric light-duty, four-wheel vehicles can achieve carbon emissions reductions at a negative cost (i.e. at a net benefit) in China. In 2030, the average MAC is estimated to be about −$140/ton CO2 for HEVs and −$515/ton CO2-saved for BEVs, varying by key parameters. The total mitigation potential of each vehicle technology is estimated to be 1.38 million tons for HEVs and 0.75 million tons for BEVs. 相似文献