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411.
412.
Jeffrey S. Fehmi Guo-Yue Niu Russell L. Scott Andrea Mathias 《Environmental monitoring and assessment》2014,186(1):395-406
Of the operations required for reclamation in arid and semi-arid regions, establishing vegetation entails the most uncertainty due to reliance on unpredictable rainfall for seed germination and seedling establishment. The frequency of successful vegetation establishment was estimated based on a land surface model driven by hourly atmospheric forcing data, 7 years of eddy-flux data, and 31 years of rainfall data at two adjacent sites in southern Arizona, USA. Two scenarios differing in the required imbibition time for successful germination were evaluated—2 or 3 days availability of sufficient surface moisture. Establishment success was assumed to occur if plants could germinate and if the drying front in the soil did not overtake the growth of seminal roots. Based on our results, vegetation establishment could be expected to fail in 32 % of years. In the worst 10-year span, six of ten plantings would have failed. In the best 10-year span, only one of ten was projected to fail. Across all assessments, at most 3 years in a row failed and 6 years in a row were successful. Funding for reclamation seeding must be available to allow reseeding the following year if sufficient amount and timing of rainfall does not occur. 相似文献
413.
Haibo Niu Adam Drozdowski Tahir Husain Brian Veitch Neil Bose Kenneth Lee 《Environmental Modeling and Assessment》2009,14(5):585-594
The benthic boundary layer transport (bblt) model was widely used in the Atlantic Canadian offshore region to assess the potential
impact zones from drilling wastes discharges from offshore oil and gas drilling. The current version of the bblt uses a single-class
settling velocity scenario, which may affect its performance, as settling velocity is size, shape, and material dependent.
In this study, the effects of settling velocity on bblt predictions were assessed by replacing this single-class settling
velocity scenario with a multi-class size-dependent settling velocity scenario. The new scenario was used in a hypothetical
study to simulate the dispersion of barite and fine-grained drilling cuttings. The study showed that the effects of settling
velocity on bblt predictions are spatial, temporal, and material dependent. 相似文献
414.
粉煤灰和二灰(粉煤灰与石灰的混合料)均为改良软土地基的添加材料。以掺粉煤灰和二灰的上海软土为研究对象,进行次固结试验和直剪试验,研究了掺入率和养护龄期对掺粉煤灰和二灰上海软土的次固结特性和强度特性的影响。次固结试验结果表明,掺粉煤灰和二灰上海软土的次固结系数随着粉煤灰和二灰掺入量的增加而大幅减小,且在相同掺入率条件下,二灰的掺入对其次固结系数影响较大。直剪试验结果表明,粉煤灰和二灰的掺入均能提高上海软土的抗剪强度,与纯上海软土相比,其抗剪强度随着养护龄期的增长而显著增大,最后均会在某一养护龄期趋于稳定。掺粉煤灰的上海软土抗剪强度随粉煤灰掺入率基本成线性增长,最佳养护龄期建议为56 d,二灰的掺入率在10%即可有效提高上海软土的抗剪强度,其最佳养护龄期建议为28 d。上述试验结论可为科学和经济的处理软土地基提供参考。 相似文献
415.
针对上海市50座城市污水处理厂进水水质,利用实际运行数据,系统分析了水质特征以及有机物、氮、磷和悬浮物之间的概率分布和相关关系。结果表明,上海市污水中BOD5、COD、SS、NH3-N、TN和TP全年浓度分布均呈正偏态分布,月中间值分布范围分别在110~150 mg/L、260~325 mg/L、140~175 mg/L、20~30 mg/L、29~37 mg/L和3~5 mg/L。水质指标BOD5和COD、TN和TP及TN和TP之间存在显著的一元线性相关关系。进水BOD5/COD值分布在0.4~0.6之间的概率为64.6%,表明进水中生化性较好。BOD5/TN分布在4~6之间的概率为35.8%,表明进水反硝化碳源不足。BOD5/TP的平均值为32.6,且大于20的累积概率为84.1%,表明污水在处理中可以满足生物除磷的需求。TN/TP比值范围在1~25,平均值为8.6,且TN/TP>5的概率为88.1,表明进水基本满足微生物生长对氮、磷的需求。 相似文献
416.
Takuro Uehara Jia Niu Xiaochen Chen Takahiro Ota Ken’ichi Nakagami 《Sustainability Science》2016,11(5):801-812
Sustainability has become an increasingly important concept in the last few decades; however, its operational usefulness has not always been clear. In other words, some sustainability assessments may not provide decision makers with the practical information necessary to perform the assessment. This study proposes a novel operational sustainable assessment framework for Integrated Coastal Zone Management (ICZM) on a regional-scale based on a feasibility study in the Seto Inland Sea in Japan. The framework draws upon three separately developed concepts: Inclusive Wealth as the technical framework for the sustainability indicators; Satoumi (a traditional Japanese multifaceted coastal zone concept); and ecosystem services science. These three concepts complement each other when seeking to corroborate an assessment framework. Indicators based on the framework and relevant to the case study site were identified. Although Satoumi is a traditional Japanese knowledge, it is believed that its application may be instructive for other areas, as similar concepts can be found and utilized for the conduct of ICZM sustainability assessments. 相似文献
417.
电动力学去除剩余污泥中重金属受到多种因素的影响,其中电解电压、电极面积、电极材料等都有较大的影响,很有必要进行条件优化研究。针对存在的问题,系统的研究了电解电压、电极面积、电极材料对电动力学修复过程的影响。研究表明,影响污泥中重金属Cu和Zn去除率的因素大小顺序为:电压电极面积电极材料;采用等于或低于氢析出电压进行电动力学修复时,更有利于提高污泥中重金属去除率;增大电极面积,提高了电流强度,有利于污泥中重金属的转化、迁移,从而提高污泥中重金属去除率;研究表明,采用低于氢析出电压和惰性电极可以有效避免电极被腐蚀。 相似文献
418.
Historical profiles and sources of PAHs at two typical sediment cores (i.e., the shipping route site and the shoal site) were fully compared to probe the controlling factors, specifically the water currents, for the PAHs deposition processes in the Yangtze River Estuary. Compared with ocean water currents, river runoff affected by the water impoundment of the Three Gorges Dam greatly affected the PAHs levels and percent contribution of PAHs sources in the two cores. River runoff hindered the PAHs deposition in shoal site, while a contrary phenomenon was observed for the shipping route site. Though the PAHs in the estuary were mainly from river catchment, only low ring PAHs in the shipping route site were mainly from the upper reach of the river. Coarse sediments with higher organic carbon content also accounted for the higher deposition levels of PAHs in the shipping route site. 相似文献
419.
高浓度钻井废水的混凝-催化氧化处理 总被引:2,自引:0,他引:2
以华北油田某深井的高浓度钻井废水(COD高达14 460.0 mg/L)为研究对象,提出了酸化-混凝-催化氧化-吸附的组合处理工艺。重点研制了钻井废水催化氧化处理催化剂(镍基催化剂),通过实验确定了最佳工艺参数条件。着重考察了催化氧化处理的工艺条件,在pH值为4,次氯酸钙投加量为4.4 g/L,催化剂投加量为1.6 g/L的条件下COD降至403.5 mg/L,进一步吸附处理后COD降至139.9 mg/L、色度为30倍、石油类含量为3.8 mg/L、pH为8.0和SS浓度为52mg/L,最终出水水质达到《污水综合排放标准》(GB 8978-1996)二级标准,处理成本为84.8元/m3。 相似文献
420.
通过振动台模型试验探讨震动强度对反倾层状岩质边坡动力响应规律的影响,着重分析边坡加速度响应峰值、加速度放大系数随震动强度增加的变化规律。结果表明:①随着震动强度增加,模型边坡各测点的加速度响应峰值不断增大,地震波频率和测点位置影响加速度响应峰值的增加方式;②震动强度对模型边坡各测点加速度放大系数的影响因地震波频率、测点位置的不同而有不同的表现。同一频率地震波作用下,相同高程的测点加速度放大系数随震动强度增加的变化规律相同;③0.20g是边坡变形破坏的临界加速度值;④震动强度的变化并不改变加速度响应峰值、加速度放大系数在边坡中的分布。该研究结果对高地震区的地质灾害防治具有指导和借鉴-意义。 相似文献