Aerobic N2O emission for activated sludge acclimated under different aeration rates in the multiple anoxic and aerobic process

Nitrous oxide (N₂O) is a potent greenhouse gas that can be emitted during biological nitrogen removal. N₂O emission was examined in a multiple anoxic and aerobic process at the aeration rates of 600 mL/min sequencing batch reactor (SBR_L) and 1200 mL/min (SBR_H). The nitrogen removal percentage was 89% in SBR_L and 71% in SBR_H, respectively. N₂O emission mainly occurred during the aerobic phase, and the N₂O emission factor was 10.1% in SBR_L and 2.3% in SBR_H, respectively. In all batch experiments, the N₂O emission potential was high in SBR_L compared with SBR_H. In SBR_L, with increasing aeration rates, the N₂O emission factor decreased during nitrification, while it increased during denitrification and simultaneous nitrification and denitrification (SND). By contrast, in SBR_H the N₂O emission factor during nitrification, denitrification and SND was relatively low and changed little with increasing aeration rates. The microbial competition affected the N₂O emission during biological nitrogen removal.     

乌鲁木齐市MODIS气溶胶光学厚度与PM10浓度关系模型研究

为了建立乌鲁木齐市近地面PM10浓度监测的关系模型,利用乌鲁木齐市2013年3—11月、2014年3—11月MODIS AOD产品与同期地面观测的PM10质量浓度进行相关分析,结果表明二者直接相关程度较低(r=0.433,p0.01);然后以WRF模式模拟的大气边界层高度及地面观测的相对湿度数据对AOD进行垂直、湿度订正后,二者相关性得到较大程度提高(r=0.630,p0.01);按照季节分类统计和订正春、夏、秋季的相关系数r分别为0.779、0.393、0.523,均大于统计学上99%的置信度要求,其中春季的订正最为有效,可用性更高;最后,建立全年和各季AOD-PM10最优拟合模型并反演乌鲁木齐市地面PM10质量浓度,全年和三季的反演结果与实测数据的相关系数分别为0.757、0.748、0.652、0.715(p0.01);同时基于卫星遥感AOD反演得到的PM10质量浓度的空间分布与AOD呈现出整体的一致性,并且3个季节AOD平均值表现为:春季秋季夏季.证实了卫星遥感AOD经过垂直和湿度订正后,可以作为辅助监测乌鲁木齐市PM10地面浓度分布的一个有效手段.     

广州市区县环境竞争力评价研究

近年来环境在城市竞争中的作用日益凸显,城市在经济转型升级的关键时期,迫切需要提升环境竞争力,以优良的环境质量和利用环境资源创造价值的能力来参与国际竞争.而城市的整体环境竞争力是在各区、县环境竞争力的基础上形成的,提升各区(县)环境竞争力有利于提升城市环境竞争力.首先论述了环境竞争力的概念及内容,构建了广州区县环境竞争力评价模型,然后对评价结果进行详细的分析,并提出有关建议.     

ICP-MS法测定环境空气TSP中铬镍铜的不确定度评定研究

对电感耦合等离子体质谱(ICP-MS)法测定环境空气TSP中铬、镍、铜的过程中可能引入的不确定度分量,包括样品采集体积、样品消解、定容体积、标准溶液配制、标准曲线拟合、重复测定等进行分析和评定,并得出扩展不确定度.结果显示,对于铬、镍、铜,样品消解和曲线拟合引入的不确定度最大,其次是重复测定和孔口流量校准器的流量校准,采样器重复性和消解定容的不确定度最小.为ICP-MS法测量环境空气TSP重金属元素的质量控制和不确定度评定提供参考依据.     

浅述职业紧张对员工健康的影响及干预策略

随着医学模式从生物医学模式向生物—心理—社会医学模式的转变,心理社会因素对健康的影响日益加重。文章探讨职业紧张与健康的关系及其可能会给作业员工健康造成的损害和相关干预措施。得出:职业紧张对健康的影响是较长时间内过大的压力所表现出来的累积性反应,其发展过程是缓慢和渐进的,可能会出现高血压、冠心病、中风、睡眠障碍等症状,在日常工作中,有必要采取有针对性的干预措施,其最基本的办法是干预生产活动中的紧张因素,提高作业员工的控制和适应能力,最终达到良性循环。     

Similarities and differences of metal distributions in the tissues of molluscs by using multivariate analyses

Multivariate analysis including correlation, multiple stepwise linear regression, and cluster analyses were applied to investigate the heavy metal concentrations (Cd, Cu, Fe, Ni, Pb, and Zn) in the different parts of bivalves and gastropods. It was also aimed to distinguish statistically the differences between the marine bivalves and the gastropods with regards to the accumulation of heavy metals in the different tissues. The different parts of four species of bivalves and four species of gastropods were obtained and analyzed for heavy metals. The multivariate analyses were then applied on the data. From the multivariate analyses conducted, there were correlations found between the soft tissues of bivalves and gastropods, but none was found between the shells and the soft tissues of most of the molluscs (except for Cerithidea obtusa and Puglina cochlidium). The significant correlations (P < 0.05) found between the soft tissues were further complemented by the multiple stepwise linear regressions where heavy metals in the total soft tissues were influenced by the accumulation in the different types of soft tissues. The present study found that the distributions of heavy metals in the different parts of molluscs were related to their feeding habits and living habitats. The statistical approaches proposed in this study are recommended for use in biomonitoring studies, since multivariate analyses can reduce the cost and time involved in identifying an effective tissue to monitor the heavy metal(s) bioavailability and contamination in tropical coastal waters.     

Decomplexation of Cr(III)-EDTA and simultaneous abatement of total Cr by photo-oxidation: efficiency and in situ reduction of intermediate Cr(VI)

Environmental Science and Pollution Research - Most prevailing processes are incapable of removing Cr(III)-organic complexes efficiently and facing the problem of in-process formation of highly...