Effects of eggshell addition on calcium-deficient acid soils contaminated with heavy metals

The eggshell was used to remediate the contaminated soil by heavy metals. The eggshell addition decreased the available state of the heavy metals. The available calcium in the soil increased due to eggshell addition. The efficiency was investigated in different moisture conditions. In this study, effects of water conditions (flooded, wet, or dry) and eggshell dosages (0, 0.1, 1.0, and 10.0 g/kg soil, respectively) on pH variation, content of unavailable state of heavy metals, form of heavy metals, and available nutritious element calcium (Ca) in acid soils contaminated with heavy metals were investigated, respectively. The soil samples were continuously cultivated indoors and analyzed by toxicity characteristic leaching procedure and community bureau of reference (BCR) sequential extraction procedure. The results showed that the addition of eggshell could effectively improve the pH of acid soil and increase it to neutral level. Moreover, the contents of unavailable state of heavy metals Cu, Zn, and Cd increased significantly. Furthermore, when the soil was cultivated under the flooded condition with 1.0 g/kg eggshell, the unavailable state of Cu, Zn, and Cd increased the most, and these heavy metals were transformed into residual state. On the other hand, the amount of available state of Ca increased to 432.19 from 73.34 mg/kg with the addition of 1.0 g/kg eggshell, which indicated that the addition of eggshell dramatically improved the available state of Ca. Therefore, eggshell could ameliorate the soil environment as it led to the decrease of available heavy metals and improvement of fertilization effectively. In a word, this study indicates that the addition of eggshell would be a new potential method for remediation of acid field soils contaminated with heavy metals.     

考虑损伤特征的冻风积土加载模型与试验研究

近几年随着宁夏电网的快速发展,火电厂及新能源的大规模接入,短路电流超标问题日益突出。本文基于转移阻抗的概念,分别从电源发展和网架变化两个方面分析了2014至2018年引起宁夏电网各电压等级短路电流超标的原因,结果表明电源接入是导致330 kV、750 kV电网短路电流超标的主要原因,引起220 kV短路电流超标的主要因素是网架变化。此外分析了各电压等级火电厂的短路电流灵敏度系数,结果表明火电厂对本电压等级的短路电流灵敏度系数最大。最后总结了近年来宁夏电网已采取的短路电流限制措施,并结合宁夏电网十三五规划,分析了宁夏电网4分区运行方案。     

安全工程专业人才培养模式及课程体系探讨

安全工程高等教育是培养安全专业人才的最主要途径,而人才培养必须首先确立人才培养目标、人才培养模式以及与此相对应的课程体系。安全工程专业的培养目标应该足培养能适应现代科学技术飞速发展和社会经济日益变化的高级安全专门人才。为此必须进行宽口径、重基础、淡专业的通才教育模式。在课程体系的设置上必须根据自身的实际情况,扬长避短,制定出具有自身特色的专业培养计划,同时要考虑到新时期人才市场的要求和高等教育的人才培养规律,只有这样才能将安全工程专业办出特色,在激烈的人才市场竞争中立于不败之地。     

Treatment of fracturing fluid waste by Fenton reaction using transition metal complexes catalyzes oxidation of hydroxypropyl guar gum at high pH

Environmental Chemistry Letters - Hydroxypropyl guar gum (HPGG), polyacrylamide (PAM) and carboxymethyl cellulose (CMC) are widely used as thickeners in...     

含锌废水的微生物处理技术

从失活生物体和活性生物体两个角度出发，介绍了目前应用微生物法去除废水中重金属锌的研究现状，详细阐述了生物絮凝、生物吸附和硫酸盐还原菌(SRB)的代谢产物(硫化氢)去除锌的机理。     

论成都的环境用水和水生态环境建设

本文首次提出环境用水概念，指出水质、水量、水面是环境用水的基本要素。阐述了环境用水对成都城市发展的重要意义。就成都环境用水目前存在的问题提出了解决途径。结合府南河综合整治工程，就成都的水生态环境建设提出建议。     

烟尘中多环芳烃的监测

已有资料给出的燃煤工业锅炉所排放烟尘中致癌性多环芳香烃（ＰＡＨｓ）含量悬殊，很难直接用于日常ＰＡＨｓ污染源的评价。作者实测了燃煤工业锅炉所排烟尘中常见的ＰＡＨｓ的含量，其中典型强致癌多环芳香烃苯并（ａ）芘（ＢａＰ）含量为０３５μｇ／ｇ。同时测量了锅炉烟尘排放工况，得到燃烧每千克煤排尘２７５ｇ的排尘率。据此计算得到燃烧每千克煤的ＢａＰ排放量为９６μｇ，该值处于已公布数据范围０３２～９９μｇ／ｋｇ的偏低一侧。并讨论了偏低的可能原因。     

区域农业资源开发与可持续发展——以江苏为例

我国系典型的人多地少国家,自然资源特别是农业资源对经济高速发展的支持能力相当薄弱,农业资源开发社会经济可持续发展中起着十分重要的作用。以江苏为例,探讨了农业资源开发与区域共同发展,经济国际化及科教兴省等战略实施之间的关系,对该区域主要农业资源开发前景进行分析,在此基础上提出了可持续发展战略下农业资源开发的途径与措施。     

生物膜反应器脱氮性能及其硝化细菌的研究

采用模拟含氮废水对自行设计制作的A/O生物膜反应器进行脱氮性能研究。研究结果表明：在水温为20～23℃、水力停留时间为18h、进水总氮质量浓度为61～78m g/L、曝气量为25L/min、进水COD分别为110～165m g/L和205～272m g/L的条件下,废水的COD去除率均在90%以上,硝化率分别为98%和95%,总氮去除率分别为50%和78%。采用荧光原位杂交技术对反应器各区域中的硝化细菌进行了检测。结果表明,反应器中的硝化菌主要为亚硝化螺菌属和硝化螺菌属,有少量亚硝化单胞菌属和硝化杆菌属存在。亚硝化菌和硝化菌在好氧区数量相对较多,在缺氧区数量相对较少。