Evaluation of nitrate source in groundwater of southern part of North China Plain based on multi-isotope

Nitrate pollution in groundwater is a serious water quality problem that increases the risk of developing various cancers.Groundwater is the most important water resource and supports a population of 5 million in Anyang area of the southern part of the North China Plain. Determining the source of nitrate pollution is the challenge in hydrology area due to the complex processes of migration and transformation. A new method is presented to determine the source of nitrogen pollution by combining the composition characteristics of stable carbon isotope in dissolved organic carbon in groundwater. The source of groundwater nitrate is dominated by agricultural fertilizers, as well as manure and wastewater. Mineralization, nitrification and mixing processes occur in the groundwater recharge area, whereas the confined groundwater area is dominated by denitrification processes.     

极端气候事件对洞庭湖水文连通性变化的影响

为揭示洞庭湖近十几年水文连通性的变化特征并对其未来变化进行预测,研究极端气候事件在洞庭湖水文连通性变化中作出的贡献,使用水文连通性指数法、ETCCDI极端气候指数、Hurst指数以及数理统计分析方法进行研究。研究结果表明：洞庭湖水文连通性整体呈现夏季>秋季>春季>冬季的特征,夏季、秋季、春季和冬季的整体连通性指数均值分别为0.95、0.88、0.81和0.63,且洞庭湖的水文连通性在近30年比较稳定;经持续性预测发现洞庭湖水文连通性Hurst指数均大于0.5,表示其在没有人类活动干扰的情况下会在未来呈延续下降的趋势;洞庭湖水文连通性指数随着水位增加逐渐增加且增速逐渐放缓,水位增加对其具有正向影响的边际递减效应;极端降水事件对洞庭湖水文连通性具有较为明显的正向影响,而极端气温事件对洞庭湖水文连通性影响作用较小。研究结果有助于充分认识洞庭湖水资源演变规律,对保障洞庭湖流域水资源安全具有重要的理论和现实意义。     

升温速率对活化黄姜水解残渣动力参数的影响

黄姜水解残渣是黄姜皂素生产中的固体废物,主要成分为木质素,是一种制备活性炭的优质材料．TG-DTG分析升温速率对活化过程有较明显的影响,运用简化模型Freeman-Carroll微分法和Ozawa及Kissinger积分法考察升温速率对活化黄姜水解残渣动力参数的影响,对集成优化活化过程有重要的指导意义．随升温速率的上升,活化能E与指前因子A基本上呈减小趋势,且E与A符合有关学者提出的“动力学补偿效应”;在同一升温速率下,动力学曲线有两个线性区域,温度较低时,挥发物的析出主要受化学控制,温度较高时,活化过程主要受扩散控制;用不同速率得出的活化能可初步判断原料的活化难易程度．     

An online method to determine chlorine stable isotope composition by continuous flow isotope ratio mass spectrometry （CF-IRMS） coupled with a Gasbench Ⅱ

An online method using continuous flow isotope ratio mass spectrometry (CF-IRMS) interfaced with a Gasbench Ⅱ was presented to determine chlorine stable isotope composition. Silver chloride (AgCl) was quantitatively derived from chloride by using silver nitrate (AgNO3), and then was reacted with iodomethane (CH3I) to produce methyl chloride (CH3Cl). A GasBench Ⅱ equipped with a PoraPlot Q column was used to separate CH3Cl from any other gas species. Finally, chlorine stable isotope analysis was carried out on CH3Cl introduced to the IRMS in a helium stream via an active open split. The minimum amount of Cl used in this method is of the order of 1.4μmol. Inter-laboratory and inter-technique comparisons show that the total uncertainty incorporating both the precision and accuracy of this method is better than 0.007%. Furthermore, ten seawaters sampled from different locations have a narrow δ 37 Cl value range from -0.008% to 0.010%, with a mean value of (0.000±0.006)%. This supports the assumption that any seawater can be representative of standard mean ocean chloride (SMOC) and used as an international reference material.     

河南省某垃圾填埋场地下水中邻苯二甲酸酯分布特征与成因

某垃圾填埋场地下水和地表水的分析测试结果表明:16个样品中,14种PAES的检测率为100%,其中DEHP的浓度最高,变化也较大,DOP的浓度较高,但是变化不明显,DEP的含量不高,浓度的变化几乎为常数。由于受水文地质条件和人工开采的影响,垃圾填埋场北侧ZK北孔的PAES的总浓度高于垃圾填埋场周围地下水和地表水中PAES的总浓度;PAEs含量和TSS、TDS、EC、pH以及芴、菲、蒽、荧蒽、芘之间没有线性关系,表明它们来源和迁移转化机理是不同的。目前垃圾场周围地下水和地表水中的PAES都没有超过国家饮用水质量标准,然而,为了防止进一步污染,必须对PAES的污染问题给予极大的关注。