Biogeographic distribution patterns of algal community in different urban lakes in China: Insights into the dynamics and co-existence

Urban lake ecosystems are significant for social development, but currently we know little about the geographical distribution of algal community in urban lakes at a large-scale. In this study, we investigated the algal community structure in different areas of urban lakes in China and evaluated the influence of water quality parameters and geographical location on the algal community. The results showed that obvious differences in water quality and algal communities were observed among urban lakes in different geographical areas. Chlorophyta was the dominant phylum, followed by cyanobacteria in all areas. The network analysis indicated that algal community composition in urban lakes of the western and southern area showed more variations than the eastern and northern areas, respectively. Redundancy analysis and structural equation model revealed that nutrients and pH were dominant environmental factors that affected the algal community, and they showed higher influence than that of iron, manganese and COD _Mn concentration. Importantly, algal community and density exhibited longitude and latitude relationship. In general, these results provided an ecological insight into large-scale geographical distributions of algal community in urban lakes, thereby having potential applications for management of the lakes.     

石英E1′心电子自旋共振信号强度的热活化研究

石英E₁′心是一种重要的顺磁性缺陷,其热活化ESR信号强度的最大值有许多新的应用,但对于获取E₁′心信号强度最大值的方法尚存不同的认识。为了进一步研究和探讨石英E₁′心信号的增强机理及石英E₁′心ESR信号强度最大值的获取方法,采用电子自旋共振（ESR）技术测量了两个冰碛物样品在300℃等温加热前和加热后石英E₁′心的ESR信号强度,结果表明：在室温下,石英E₁′心信号强度随辐照剂量的增加而增强是由于伪E₁′心的形成而造成的;而石英E₁′心信号强度随辐照剂量增加而减弱可能是因为辐照使已增强的E₁′心产生衰退。300℃的等温热退火实验（分为15 min和20 min）结果表明：获取E₁′心ESR信号强度的最大值需要人工辐照,人工辐照的作用不仅是提供更多的空穴,而且可能更有利于氧空位向E₁′心转化。     

滇池沉积物内源氮释放风险及控制分区

采用淹水培养法测定了滇池20cm沉积物可释放态氮(EN)、潜在可释放态氮(MN)及稳定态氮(FN)含量,并分析了其空间分布特征,结合沉积物定年数据计算了不同形态氮蓄积量.依据沉积物-水界面氮释放通量、EN蓄积量及MN蓄积量对滇池沉积物内源氮污染状况进行分区,评估了不同区域滇池沉积物内源氮释放风险,并对不同分区提出了污染控制措施.结果表明,滇池沉积物内源氮释放风险:外海南部 >外海北部 >外海中部 >草海,潜在释放风险:外海南部 >外海中部 >草海 >外海北部;滇池沉积物氮污染有由北向南转移趋势;滇池全湖20cm沉积物蓄积TN5757.90t,EN637.72t,MN1320.76t,FN3799.42t.根据沉积物氮污染滇池可划分为高污染区、中度污染区、低污染区及安全区,分别占全湖面积的13.51%、15.02%、46.06%、25.42%,其中高污染区主要分布在草海、外海北部盘龙江附近;中度污染区主要分布在高污染区以下从宝象河到观音山区域及滇池出水口海口等区域;低污染区主要分布在中度污染区以下从广谱大沟到整个外海南部区域.高污染区可采取底泥环保疏浚技术,中度污染区可采取安全生态性高的原位控制技术,低污染区可采取覆盖技术,配合水生植被修复技术.     

Degradation of carbon tetrachloride in thermally activated persulfate system in the presence of formic acid

The thermally activated persulfate (PS) degradation of carbon tetrachloride (CT) in the presence of formic acid (FA) was investigated. The results indicated that CT degradation followed a zero order kinetic model, and CO ₂ ^– · was responsible for the degradation of CT confirmed by radical scavenger tests. CT degradation rate increased with increasing PS or FA dosage, and the initial CT had no effect on CT degradation rate. However, the initial solution pH had effect on the degradation of CT, and the best CT degradation occurred at initial pH 6. Cl^– had a negative effect on CT degradation, and high concentration of Cl^– displayed much strong inhibition. Ten mmol·L^–1HCO ₃ ^– promoted CT degradation, while 100 mmol·L^–1NO ₃ ^– inhibited the degradation of CT, but SO ₄ ^2– promoted CT degradation in the presence of FA. The measured Cl–concentration released into solution along with CT degradation was 75.8% of the total theoretical dechlorination yield, but no chlorinated intermediates were detected. The split of C-Cl was proposed as the possible reaction pathways in CT degradation. In conclusion, this study strongly demonstrated that the thermally activated PS system in the presence of FA is a promising technique in in situ chemical oxidation (ISCO) remediation for CT contaminated site.     

Enhanced degradation of trichloroethene by calcium peroxide activated with Fe(III) in the presence of citric acid

Trichloroethene (TCE) degradation by Fe(III)-activated calcium peroxide (CP) in the presence of citric acid (CA) in aqueous solution was investigated. The results demonstrated that the presence of CA enhanced TCE degradation significantly by increasing the concentration of soluble Fe(III) and promoting H₂O₂ generation. The generation of HO? and O₂^-? in both the CP/Fe(III) and CP/Fe(III)/CA systems was confirmed with chemical probes. The results of radical scavenging tests showed that TCE degradation was due predominantly to direct oxidation by HO?, while O₂^-? strengthened the generation of HO? by promoting Fe(III) transformation in the CP/Fe(III)/CA system. Acidic pH conditions were favorable for TCE degradation, and the TCE degradation rate decreased with increasing pH. The presence of Cl^-, HCO₃^-, and humic acid (HA) inhibited TCE degradation to different extents for the CP/Fe(III)/CA system. Analysis of Cl^- production suggested that TCE degradation in the CP/Fe(III)/CA system occurred through a dechlorination process. In summary, this study provided detailed information for the application of CA-enhanced Fe(III)-activated calcium peroxide for treating TCE contaminated groundwater.     

干扰素生产废水处理试验及生物相分析

采用水解酸化与生物接触氧化组合工艺对干扰素生产废水进行试验研究,并考察其处理效果,观察生物接触氧化工艺中生物相。结果表明：该组合工艺对出水COD的去除率大于90%,出水COD低于40 mg/L,且运行稳定后生物接触氧化槽中污泥浓度较低。对生物相的显微镜观察可知生物接触氧化槽中生物相种类以藻类为主。     

淮北平原“四水”转化模型实验研究与应用

论文基于野外实验,采用五道沟实验站和杨楼实验区1965-2007年长系列资料,考虑土壤水垂向运动和再分布、冠层截留、蒸发、填洼、大孔隙、潜水排出补给地表水等要素,采用野外实验数据逐步细化和确定参数,提出淮北平原集总式“四水”转化模型,并提出一种新的冠层截留量年内分布确定方法。模型物理意义明确,对资料的要求较低,实用性较强。模型在杨楼流域应用结果表明,模拟流量过程线精度较高,在潜水位变动过线的拟合上效果较优,在径流过程和土壤含水量的拟合上表现较好。通过模型逐年计算统计,得出杨楼实验流域1991-2007年逐年及多年平均“四水”转化定量关系,为该区水文预报和作物水利用提供技术依据。     

300MW机组锅炉屏式过热器爆管原因分析

某电厂300MW机组锅炉在投产运行仅仅13260小时便发生了屏式过热器爆管事故,经初步分析该不锈钢管弯管是由于固溶化处理不当,在残余应力、热应力及氟离子等共同作用下,在奥氏体晶界薄弱处产生晶间腐蚀微裂纹,继而不断发展并最终造成爆管事故的发生。建议加强原材料验收检验及规范锅炉运行操作规程,以最大限度减少此类事故的发生。     

Characterization and source identification of submicron aerosol during serious haze pollution periods in Beijing

Submicron aerosol is of extensive concern not only due to its significant impact on air quality but also because it is detrimental to human health. In this study, we investigated the characteristics, sources and chemical processes of submicron aerosol based on realtime online measurements of submicron aerosols（NR-PM 1） during December 2015 at an urban site in Beijing. The average mass concentration of NR-PM 1 was 92.5 ±84.9 μg/m³, the hourly maximum was 459.1 μg/m³ during t...