Seasonal variation characteristics of hydroxyl radical pollution and its potential formation mechanism during the daytime in Lanzhou

Hydroxyl free radicals (OH radicals) play the main role in atmospheric chemistry and their involving reactions are the dominant rate determining step in the formation of secondary fine particulate matter and in the removal of air pollutants from the atmosphere. In this paper, we studied the seasonal variation characteristics of OH radicals during the daytime in Lanzhou and explored the potential formation mechanism of high concentration OH radicals. We found that the OH radicals in four seasons was 2.7 × 10⁶, 2.6 × 10⁶, 3.1 × 10⁶, and 2.2 × 10⁶ cm^?3, respectively. Since the rainfall was concentrated in summer, the wet deposition had a significant effect on removing OH radicals. Among the four pollutants (including ozone (O₃), volatile organic compounds (VOCs), nitrogen dioxide (NO₂) and fine particulate matter (PM_2.5)), the variation of OH radicals were closely related to ozone concentration especially in spring and summer. In autumn, the correlation between PM_2.5 and OH radicals were the closest among the observing pollutants and its formation mechanism was different conventional regeneration pathway. In Event 1, high concentration of ozone was the main source of OH radicals; under the high humidity condition, except for ozone, the multiple factors including VOCs, NO₂ and PM_2.5 interplayed and leaded to the Event 2.     

A high activity of Ti/SnO2-Sb electrode in the electrochemical degradation of 2,4-dichlorophenol in aqueous solution

Electrochemical degradation of 2,4-dichlorophenol (2,4-DCP) in aqueous solution was investigated over Ti/SnO₂-Sb anode. The factors influencing the degradation rate, such as applied current density (2-40 mA/cm²), pH (3-11) and initial concentration (5-200 mg/L) were evaluated. The degradation of 2,4-DCP followed apparent pseudo first-order kinetics. The degradation ratio on Ti/SnO₂-Sb anode attained > 99.9% after 20 min of electrolysis at initial 5-200 mg/L concentrations at a constant current density of 30 mA/cm² with a 10 mmol/L sodium sulphate (Na2SO4) supporting electrolyte solution. The results showed that 2,4-DCP (100 mg/L) degradation and total organic carbon (TOC) removal ratio achieved 99.9% and 92.8%, respectively, at the optimal conditions after 30 min electrolysis. Under this condition, the degradation rate constant (k) and the degradation half-life (t_1/2) were 0.21 min^-1 and (2.8±0.2) min, respectively. Mainly carboxylic acids (propanoic acid, maleic acid, propanedioic acid, acetic acid and oxalic acid) were detected as intermediates. The energy efficiencies for 2,4-DCP degradation (5-200 mg/L) with Ti/SnO₂-Sb anode ranged from 0.672 to 1.602 g/kWh. The Ti/SnO₂-Sb anode with a high activity to rapid organic oxidation could be employed to degrade chlorophenols, particularly 2,4-DCP in wastewater.     

污水处理中的污泥源头减量技术研究及应用进展

污水处理厂中大多采用活性污泥法处理污废水,此法通常会产生大量剩余污泥,而污泥的处理处置费用较高,并且处置不当易对环境造成污染,因此若从源头控制减少污泥的产生则是更为理想的污泥减量方法.本文介绍了几种污泥源头减量工艺技术,如微生物强化技术、微生物固定化技术、解偶联技术(投加解偶联剂、好氧-沉淀-厌氧工艺)、强化隐性生长(物理、化学及生物法溶胞)及微型动物摄取污泥和捕食技术等,并阐述了各技术应用情况,为污泥处理技术人员提供参考方案.在水处理工程中需结合实际情况考虑选用合适的技术.     

Involvements of chloride ion in decolorization of Acid Orange 7 by activated peroxydisulfate or peroxymonosulfate oxidation

The effects of Cl^- on the decolorization of AO7 by SO₄^·- based-peroxydisulfate or peroxymonosulfate oxidation under various activated conditions were different.     

生活垃圾可持续化填埋

通过对中国填埋场现状分析,提出了"可持续填理"的概念.认为生活垃圾填埋场将从单纯的最终处置场所演变为填埋与中转相结合的场所.填埋场的可持续发展也将从两方面得到体现:一为垃圾降解过程及其副产品处理中以能量形式得到利用,另一方面为稳定化后的垃圾及填埋场本身空间得到再一次的利用.     

Evaluating the effect of rainfall variability on vegetation establishment in a semidesert grassland

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.     

Modeling the dispersion of drilling muds using the bblt model: the effects of settling velocity

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.     

掺粉煤灰和二灰上海软土的力学特性∗

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。     

上海市污水处理厂进水水质特征的统计学分析

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。     

A sustainability assessment framework for regional-scale Integrated Coastal Zone Management (ICZM) incorporating Inclusive Wealth,Satoumi, and ecosystem services science

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.