Circulation in Tasman Bay   总被引：4，自引：4，他引：0  

R. A. Heath 《新西兰海洋与淡水研究杂志》2013,47(3):469-483

Direct current measurements at four locations in Tasman Bay and numerical model results are used to analyse the mean flow in Tasman Bay. The mean circulation conforms to that previously found from drift card experiments: a clockwise circulation in Golden Bay, and an anti‐clockwise flow in Tasman Bay, with a return south‐westerly flow on the coast near Nelson. Typical mean speeds are 0.02–0.05 m.s^‐1. The circular flow appears asymmetrical in both bays, with a stronger outflow along Farewell Spit in Golden Bay and near D'Urville Island in Tasman Bay.

An analytical tidal solution is used to exhibit the influence of Cook Strait in producing smaller tidal amplitudes in eastern Tasman Bay. Tidal speeds of 0.15–0.30 nus^‐1 are typical, with tidal ellipses having degenerated into north‐east, south‐west lines.  相似文献   

非平衡吸附模型在研究渗滤液对土壤污染影响中的应用     

陈记文  薛强  刘磊  赵颖 《岩土力学》2006,27(12):2186-2190

分析了有机污染物在土壤中的迁移转化机理，建立了非平衡吸附作用下渗滤液中有机污染物在土壤中迁移转化的动力学模型，给出了模型的数值解法，模拟出渗滤液在非平衡吸附作用下的污染过程；同时还探讨了模型参数降雨量p，垃圾土土层的厚度h，含水率θ等对有机污染物运移的影响。结果表明：在总的污染源一定的情况下，降雨量的增大和污染土层厚度的增大会使得下层土壤中有机物的浓度降低，为定量研究有机污染物在土壤-水环境系统中分配与归宿提供理论依据，同时也可为监测、治理和恢复地下水污染提供一定的科学根据。  相似文献   

山东淄博市大武水源地裂隙岩溶水中污染物运移的数值研究   总被引：11，自引：0，他引：11  

朱学愚  刘建立 《地学前缘》2001,8(1):171-178

在分析研究淄博市大武水源地裂隙岩溶含水层的水力性质和污染物运移特征的基础上 ,对裂隙岩溶水的水头和污染物运移进行数值研究。目前国内外对裂隙岩溶水进行数值计算时 ,通常用等价多孔介质模型 ,但裂隙岩溶介质和多孔介质有很大不同。裂隙岩溶介质的储水和导水空间为裂隙网络 ,导水系数大 ,地下水的实际平均流速比孔隙水大得多 ,但给水度和贮水系数小。当用等价多孔介质模型进行模拟时应考虑这些特点。对于污染物运移的模拟 ,要同时求解水头方程和对流弥散方程 ,可采用MODFLOW和MT3D软件进行模拟。研究区裂隙岩溶水水头的数值计算表明 ,等效多孔介质模型水头的拟合误差能满足国标GB/T144 97- 93的要求。各时段地下水水量均衡计算的精度也满足要求。对流弥散方程的数值计算 ,由于Peclet数高达 95 .6 7,对流占绝对优势 ,可能存在数值弥散和数值振荡 ,因而采用多种方法进行了比较。对于同一问题 ,同时采用上游有限差分法 (UFDM) ,混合的欧拉拉格朗日方法 (特征线法MOC、改进特征线法MMOC和混合特征线法HMOC) ,总变异消减法(TVD)进行计算 ,并比较其结果。结果表明 ,混合特征线法 (HMOC)和总变异消减法 (TVD)比较适合于对流占优势的运移问题计算。由于渗透系数K和有效孔隙度θ对溶质运移结果的影响很大 ,?  相似文献   

Towards an integrated management framework for emerging disaster risks in Japan   总被引：2，自引：1，他引：1  

Saburo Ikeda  Teruko Sato  Teruki Fukuzono 《Natural Hazards》2008,44(2):267-280

An integrated framework for disaster risk management is presented to cope with the risk of low-probability high-consequence (LPHC) disasters in urban communities. Since the 2000 Tokai flood in Japan, there has been a shift in the management strategy from disaster prevention with a presumed zero risk to disaster reduction with an acceptable risk. The framework consists of: (i) integration of a different categories of risk reduction options in terms of structural and nonstructural measures, regulation and market-oriented measures, (ii) strengthening of the capacity of local communities to make their own management choices for LPHC-type disaster risks, and (iii) promoting the participation of stakeholders throughout the entire cycle of risk management. The interdisciplinary framework is discussed with reference to lessons learned from two recent major flood disasters (the 2000 Tokai flood and the 2004 Niigata flood). To implement the goals of the integrated framework, a participatory platform for disaster risk communication called “Pafrics” has been developed. Preliminary results of the pilot study of participation and risk communication supported by Pafrics are presented.  相似文献   

Necessity-driven circular economy in low-income contexts: How informal sector practices retain value for circularity     

《Global Environmental Change》2022

Low-income informal sector contexts are rife in practices that retain value of materials and goods, but in the academic literature and policy debates these practices are seldom considered as part of the circular economy (CE). This is a major omission in CE discourse, as over 60 percent of the world’s employed population is in the informal sector and many of them make their living from circularity practices. Hence, our paper advances a globally covering understanding of CE by focusing on local practices constituting CE in the overlooked contexts of low-income informal markets of emerging economies, and on the motives behind the practices. To that end we introduce the notion of Necessity-Driven Circular Economy, defined as a set of locally embedded and interlinked formal and informal practices aimed at restoring and retaining the value of goods and materials for as long as possible, based on economic necessity and opportunities for income generation. We substantiate this conceptual work with our empirical findings from low-income urban communities in Brazil, India, and Tanzania. This allows us to capture the essential characteristics of necessity-driven circular economy. These characteristics draw attention to the social and cultural embeddedness and the interweaving of consumption and production in necessity-driven circular economy, as opposed to the dominant techno-economic and industry-focused circular economy conceptualizations that are typical in academic discourse and portray developed country contexts. Finally, we discuss conceptual and practical relevance of necessity-driven circular economy and point out its system-level implications for policymakers and businesses.  相似文献   

地下水土有机污染MNA修复研究综述     

焦殉 《上海国土资源》2011,32(2):30-35

监测自然衰减技术（MNA）是修复地下水土有机污染最经济和有效的方法之一。在自然衰减的评价中,美国主要是从3个方面的证据来揭示自然衰减的发生：污染物质量减少;表征生物降解的地球化学指标的变化;通过微生物降解菌研究为生物降解提供直接证据。本文总结了目前国际上获取自然衰减证据的主要方法：污染物浓度变化趋势统计法、污染物质量守恒和质量通量分析法、溶质运移的解析模型、溶质运移的数值模型、地球化学证据方法、稳定同位素方法和微生物菌群研究等方法。我国在自然衰减评价方面的研究较少。由于自然衰减修复时间较长、修复效率较低,在实际应用中,联合运用强化衰减修复技术和MNA技术成为地下水土治理的主要发展趋势。  相似文献   

Large and growing environmental reservoirs of Deca-BDE present an emerging health risk for fish and marine mammals   总被引：2，自引：0，他引：2  

Ross PS  Couillard CM  Ikonomou MG  Johannessen SC  Lebeuf M  Macdonald RW  Tomy GT 《Marine pollution bulletin》2009,58(1):7-10

Polybrominated diphenyl ethers (PBDEs) have been the subject of intense scientific and regulatory scrutiny during recent years. Of the three commercial forms (Penta, Octa and Deca) of PBDEs that have been widely used as flame retardants in textiles, furniture upholstery, plastics, and electronics, only Deca-BDE remains on the general market in North America, while a recent ruling of the European Court spells an impending end to its use in Europe. We review here highlights of aquatic research documenting the rapid emergence of PBDEs as a high priority environmental concern in Canada. PBDEs are being introduced in large quantities to the aquatic environment through sewage discharge and atmospheric deposition. In certain environmental compartments, the single congener BDE-209, the main ingredient in the Deca-BDE formulation, has surpassed the legacy PCBs and DDT as the top contaminant by concentration. Limited biomagnification of BDE-209 in aquatic food webs reflects its high log K_ow and preferential partitioning into the particle phase. As a result, large environmental reservoirs of BDE-209 are being created in sediments, and these may present a long-term threat to biota: BDE-209 breaks down into more persistent, more bioaccumulative, more toxic, and more mobile PBDE congeners in the environment.  相似文献   

Monitoring of organic contaminants in sediments from the Korean coast: Spatial distribution and temporal trends (2001-2007)     

Choi HG  Moon HB  Choi M  Yu J 《Marine pollution bulletin》2011,62(6):1352-1361

Spatial and temporal trends of organic contaminants in sediments along the Korean coast were estimated through a nationwide environmental monitoring program from 2001 to 2007. The concentrations of organic contaminants in sediments along the Korean coast were relatively low or moderate compared with foreign studies. The mean detection frequencies of organic contaminants during the seven years were highest for PAHs and PCDD/Fs, followed by PCBs, DDTs, TBT and HCHs in decreasing order. Based on published sediment quality guidelines, the ecological risks of persistent organic pollutants in sediments along the Korean coast were low, despite exceedances of the ERL at 2-6 sites for DDTs, and the TEL at 9-18 sites for PCDD/Fs. Nonparametric tests to assess temporal trends revealed significant decreasing trends for PCBs and PCDD/Fs at four and three sites, respectively (p < 0.05). These results reflect the effects of regulations on the use of those contaminants.  相似文献   

Transformations and hydraulic captures of petrochemical contaminants in a karst-fractured aquifer   总被引：2，自引：0，他引：2  

Yudao Chen  Xueyu Zhu  Xueshun Zhu  Yaping Jiang  Qinglin Xie 《Environmental Geology》2000,39(11):1304-1308

 The development of a petrochemical industry may be responsible for petrochemical contamination of karst-fractured aquifers in an urban water supply system. In the Dawu Well Field, a karst-fractured aquifer in Zibo City, in the east of China, has been seriously polluted by petrochemicals from the operation of petrochemical plants. More than 60 species of organic contaminants have been detected in the water supply wells of the Liuhang-Hougao zone, in the west part of Dawu Well Field. Investigations indicate that contaminants are transported from the petrochemical plants to the karst-fractured aquifer along karst fractures and the Jinling Fault. In the groundwater, concentrations of pollutants vary with depth. Concentrations are greater with depth because of the transmissibility of the Jinling fault. The local convective flow field has a significant influence on transportation of contaminants. Hydraulic barriers can prevent the transportation of contaminants and they can be removed by extraction. Received: 22 October 1999 · Accepted: 14 February 2000  相似文献   

不同土壤有机质组分对憎水有机物的吸附机理研究   总被引：15，自引：2，他引：15  

陈迪云  黄伟林 《地球化学》2003,32(4):368-374

采用完全混合一步平衡反应实验方法，选择菲、萘、三氯苯和二甲苯作为憎水有机物(HOCs)的探针，研究了它们在土壤及其中的胡敏酸、胡敏素等有机质组分中的等温平衡吸附行为，探讨了非线性吸附的机制。结果表明，HOCs在水与土壤体系中表现为非线性吸附，其非线性的吸附行为主要受到土壤有机质(SOMs)的控制。SOMs具有高度不均匀的性质，HOCs表现出非线性吸附行为是其在不同的SOMs相扩散转移以及在相对聚结的胡敏素和“黑炭”的表面吸附的结果。  相似文献