Adsorption of fluoride on clay minerals and their mechanisms using X-ray photoelectron spectroscopy

This research investigates the adsorption mechanisms of fluoride (F) on four clay minerals (kaolinite, montmorillonite, chlorite, and illite) under different F^? concentrations and reaction times by probing their fluoride superficial layer binding energies and element compositions using X-ray photoelectron spectroscopy (XPS). At high F^? concentrations (C ₀ = 5?C1000 mg·L^?1), the amount of F^? adsorbed (Q _F), amount of hydroxide released by clay minerals, solution F^? concentration, and the pH increase with increasing C ₀. The increases are remarkable at C ₀>50 mg·L^?1. The QF increases significantly by continuously modifying the pH level. At C ₀<5?C100 mg·L^?1, clay minerals adsorb H⁺ to protonate aluminum-bound surface-active hydroxyl sites in the superficial layers and induce F^? binding. As the C ₀ increases, F^?, along with other cations, is adsorbed to form a quasi-cryolite structure. At C ₀>100 mg·L^?1, new minerals precipitate and the product depends on the critical Al³⁺ concentration. At [Al³⁺]>10^?11.94 mol·L^?1, cryolite forms, while at [Al³⁺]<10^?11.94 mol·L^?1, AlF₃ is formed. At low C ₀ (0.3?C1.5 mg·L^?1), proton transfer occurs, and the F^? adsorption capabilities of the clay minerals increase with time.     

兰州市化石燃料燃烧源排放VOCs的臭氧及二次有机气溶胶生成潜势

随着我国工业的快速发展和城市化进程的加快,化石燃料的大量使用造成了严重的二氧化硫、颗粒物和挥发性有机物(volatile organic compounds,VOCs)等大气污染.目前,对化石燃料燃烧排放挥发性有机物环境影响的研究较少,本文计算了兰州市化石燃料燃烧源排放VOCs及其相应的臭氧生成潜势(ozone formation potential,OFP)和二次有机气溶胶生成潜势(secondary organic aerosols formation potential,SOAFP),其中水泥制造业的OFP和SOAFP占比最大,分别为45. 3%、50. 9%;其次为砖瓦制造业,但其吨标煤燃烧排放VOCs的OFP和SOAFP值最高,折为吨标煤后天然气燃烧产生VOCs的O_3和SOA最小.兰州市主城区化石燃料燃烧源OFP和SOAFP主要为电力和热力的生产供应以及西固区工业企业排放VOCs的贡献,其它地区为水泥制造业、砖瓦制造业、钢铁冶炼业等高能耗的行业的贡献为主.芳香烃是化石燃料燃烧源排放VOCs中对OFP和SOAFP均贡献最大的一类物质,占比分别为40. 0%和67. 2%,并且在生成潜势贡献前10的物种中芳香烃为主要物种.与生物质燃烧源相比,化石燃料燃烧源具有较强的O_3和SOA生成能力(2. 58 t·t~(-1)和3. 16 kg·t~(-1)).     

CASTEX连续铸挤的侧向扩展挤压挤压力计算

以金属铅为坯料进行侧向扩展挤压模拟CASTEX机的径向扩展挤压.由变形流动规律建立简化力学模型推导挤压力计算公式并进行验证.     

GIS技术在土地资源估价中的应用分析

本文主要分析了GIS技术的功能、概念、发展及基于该技术的土地估价信息系统的组成、功能和优越性。为土地估价提供了强有力的技术支持和科学依据     

Prediction model of mercury accumulation in fish of reservoirs

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我国地质矿产部门工业卫生现状

对地质矿产部门１９９１年初至１９９２年底开展的工业卫生普查工作资料进行分析，简述了职业危害人群分布、现场监测、职业病的现状及危害原因，提出了防护措施和改进意见。     

区际生态补偿机制是区域间协调发展的关键

环境问题和环境资源关系已成为重要的区际社会关系和社会矛盾，极大的影响和抑制区域协调发展，首先探讨区际环境问题和环境关系的成因、类型、数量动态、时空演变格局；独创性的剖析区际环境关系、区际环境问题难以解决的深刻根原。深入研究区际生态补偿作用和影响，指明缺乏补偿是江河上游与下游地区间矛盾产生的重要原因，也是环境问题难以解决的重要原因。指出区际生态补偿体系应由政策法律制订机构、补偿计算机构、补偿征收管理机构等组成；同时着重研究计算策略思路、计算方法、计算过程、计算结果表达等生态补偿计算有关问题；分析建立区际生态补偿机制在环境资源管理体制、绿色国民经济核算体系（转移支付制度）、环境影响数量技术、环境问题争端协调等面临的诸多困难。     

SBR法处理城市生活污水的研究

介绍了ＳＢＲ法处理城市生活污水的小试。结果表明：ＳＢＲ法能获取较好的出水水质。总ＢＯＤ、溶解性ＢＯＤ、总ＣＯＤ、溶解性ＣＯＤ、氨氮和悬浮物去除率分别为９４．４／～９６．６％，９２．６％～９６．２％，８４．１％～８７．３％，６１％～６９％，７８．１％～８４．３％和９１．９％～９５．１％。为了适应农业灌溉的需要，还应采取深层石英砂过滤进一步降低浊度。     

Prenatal diagnosis of triple X using fetal cells obtained by endocervical lavage

Prenatal diagnosis of aneuploidies currently relies on invasive procedures such as chorionic villous sampling and amniocentesis. These methods can provide an accurate diagnosis of the fetal karyotype but are relatively invasive. Here, we report a case of the prenatal detection of triple X using fetal cells obtained by lavage of the endocervical canal prior to amniocentesis, following ultrasound diagnosis of hydrops fetalis. Copyright © 2003 John Wiley & Sons, Ltd.