Intervention factors associated with environmental stressors resulting from cross-provincial transfers by coal resource-based enterprises

Environmental Geochemistry and Health - The environmental stressors associated with the cross-provincial transfer of coal resource-based enterprises (CREs) have become a critical concern for the...     

Association of hearing loss with total and cause-specific mortality in US adults

Environmental Science and Pollution Research - We expected to explore the associations of hearing loss and hearing thresholds at different frequencies with total and cause-specific mortality. In...     

Enhanced reductive degradation of carbon tetrachloride by carbon dioxide radical anion-based sodium percarbonate/Fe(II)/formic acid system in aqueous solution

Complete CT degradation was achieved by SPC/Fe(II)/FA system.Formic acid established the reductive circumstance by producing CO₂·^–.CO₂·^– was the dominant active species responsible for CT degradation.CT degradation was favorable in the pH range from 3.0 to 9.0.SPC/Fe(II)/FA system may be suitable for CT remediation in contaminated groundwater.The performance of sodium percarbonate (SPC) activated with ferrous ion (Fe(II)) with the addition of formic acid (FA) to stimulate the degradation of carbon tetrachloride (CT) was investigated. Results showed that CT could be entirely reduced within 15 min in the system at a variety of SPC/Fe(II)/FA/CT molar ratios in experimental level. Scavenging tests indicated that carbon dioxide radical anion (CO2·^–) was the dominant reactive oxygen species responsible for CT degradation. CT degradation rate, to a large extent, increased with increasing dosages of chemical agents and the optimal molar ratio of SPC/Fe(II)/FA/CT was set as 60/60/60/1. The initial concentration of CT can hardly affect the CT removal, while CT degradation was favorable in the pH range of 3.0–9.0, but apparently inhibited at pH 12. Cl^– and HCO₃^– of high concentration showed negative impact on CT removal. Cl^– released from CT was detected and the results confirmed nearly complete mineralization of CT. CT degradation was proposed by reductive C-Cl bond splitting. This study demonstrated that SPC activated with Fe(II) with the addition of FA may be promising technique for CT remediation in contaminated groundwater.     

Chemical composition of the mycelium of Daldinia eschscholtzii北大核心CSCD

To investigate the chemical composition of the fungus Daldinia eschscholtzii, the compounds were separated by silica gel, Sephadex LH-20, and preparative chromatography. Their structures were identified by spectral methods. The MTT method was applied to measure the cytotoxicity of representative components. Eleven compounds were isolated and identified as 3β-hydroxyl-6,22-dien-5α,8α-peroxynitrite (1); ergosterol-9(11)-dehydroperoxide (2); mangiferonic acid (3); ergosta-4,6,8 (14),22-tetraen-3-one (4); (+)-syringaresinol (5); 3,5,3',5'-tetramethoxy-4,4,-diphenol (6); 5-methoxycoumarin (7); 5-hydroxy-2-methyl-4H-chromen-4-one (8); (2R,4R)-3,4-dihydro-5-methoxy-2-methyl-2H-1-benzopyran-4-ol (9); 2,3-dihydro-5-methoxy-2-methylchromen-4-one (10); and 7β-caruilignan C (11), respectively. Compound 4 showed inhibitory activity against H1299, H460, HGC-27, A5491, and MNK-45, with the IC50 value of 25.2 ± 2.9, 32.3 ± 4.2, 29.2 ± 1.2, 33.9 ± 3.7, and 18.0 ± 7.0 μmol/L, respectively. © 2018 Science Press. All rights reserved.     

土壤中三卤甲烷(THMs)前驱物质流出的规律

通过室内模拟淋溶实验,初步探讨了以三卤甲烷生成潜能(THMFP)为指标的土壤三卤甲烷前驱物质的流出规律.结果显示:土壤淋出液中THMFP的浓度与土壤性质特别是土壤中腐殖质含量、组成与卤代活性,模拟雨水的酸度及累积淋溶量等有关.土壤中所含腐殖质的量越大、腐殖质的卤代活性越高且溶解迁移能力越强,则淋出液中THMFP的浓度越大;酸度最低(pH3.0)的模拟雨水淋洗下,淋出液中THMFP的浓度最低;模拟雨水的pH值愈低,土壤THMFP愈易流出;本实验条件下,淋出液中THMFP的浓度随累积淋溶量的增大呈下降趋势.     

信息素调控质粒介导的粪肠球菌耐药基因接合转移机制研究进展

粪肠球菌是一种在自然环境中广泛存在的革兰氏阳性细菌.由于其特殊的耐药机制及高频率的耐药基因转移方式,导致了环境中耐药粪肠球菌的广泛传播,生态安全形势严峻.其中,信息素应答质粒介导的粪肠球菌耐药基因的接合转移是造成粪肠球菌耐药基因快速扩散的重要方式.本文回顾了近些年关于信息素应答质粒接合转移的研究成果,分析总结了接合转移的必要条件、正负调控信息素对接合转移的调节作用,并以携带四环素抗性的质粒pCF10为例简要探讨了接合转移相关基因、蛋白的调控机制,旨在更加全面地揭示粪肠球菌的耐药基因传播机制,为耐药细菌的基因转移机制研究提供参考.     

椰壳生物炭对多种重金属在广东水稻土中的吸附解吸特性影响

土壤中有毒有害重金属会造成环境污染并危害人体健康.本文基于OECD 106实验准则,采用批量平衡实验方法,研究了多种有效态重金属镉(Cd2+)、钴(Co2+)和铜(Cu2+)在广东省水稻土中的吸附解吸行为特征以及添加椰壳生物炭对吸附解吸行为的影响,并探讨了pH值、温度和添加炭含量对吸附率的影响.结果表明,3种重金属在土壤中的吸附平衡时间为25 h,解吸平衡时间为30 h,添加质量浓度5％椰壳生物炭可使土壤对3种重金属的吸附率提高11.6％ ～20.0％,重金属离子在土壤中的吸附为不可逆吸附,具有明显滞后效应,Cd2+、Co2+和Cu2+的解吸滞后系数分别为33.838、1.347和0.972.在本试验条件下,土壤溶液的pH值随椰壳生物炭含量的增加而增大,温度和含炭量对吸附率的影响呈良好的线性关系(r2>0.951).这表明,在土壤中施用椰壳生物炭能有效缓解土壤中的重金属污染.     

Sludge fermentation liquid addition attained advanced nitrogen removal in low C/N ratio municipal wastewater through short-cut nitrification-denitrification and partial anammox

• Sludge fermentation liquid addition resulted in a high NAR of 97.4%. • Extra NH₄⁺-N from SFL was removed by anammox in anoxic phase. • Nitrogen removal efficiency of 92.51% was achieved in municipal wastewater. • The novel system could efficiently treat low COD/N municipal wastewater. Biological nitrogen removal of wastewater with low COD/N ratio could be enhanced by the addition of wasted sludge fermentation liquid (SFL), but the performance is usually limited by the introducing ammonium. In this study, the process of using SFL was successfully improved by involving anammox process. Real municipal wastewater with a low C/N ratio of 2.8–3.4 was treated in a sequencing batch reactor (SBR). The SBR was operated under anaerobic-aerobic-anoxic (AOA) mode and excess SFL was added into the anoxic phase. Stable short-cut nitrification was achieved after 46d and then anammox sludge was inoculated. In the stable period, effluent total inorganic nitrogen (TIN) was less than 4.3 mg/L with removal efficiency of 92.3%. Further analysis suggests that anammox bacteria, mainly affiliated with Candidatus_Kuenenia, successfully reduced the external ammonia from the SFL and contributed approximately 28%–43% to TIN removal. Overall, this study suggests anammox could be combined with SFL addition, resulting in a stable enhanced nitrogen biological removal.     

缺氧—好氧—催化臭氧氧化工艺处理石化厂含盐废水

采用缺氧—好氧—催化臭氧氧化工艺处理某石化厂的含盐废水。实验结果表明：在进水COD为200~350 mg/L的条件下,经生化处理后的出水COD稳定在50~60 mg/L,COD去除率稳定在75%左右;在臭氧投加量为4.5 g/L、V（催化剂Ⅱ）∶V（废水）=1.5∶1的条件下,进行连续催化臭氧氧化后出水COD稳定在20 mg/L以下,COD去除率大于70%,满足DB 61/224—2011《黄河流域（陕西段）污水综合排放标准》。表征结果显示,催化剂表面含有铜元素,比表面积为250.815 m²/g,吸水率为60.9%,经过滤可去除废水中残留的催化剂。     

废弃电路板中环氧树脂真空热解规律的研究

真空条件下,应用程序升温管式电炉对废弃电路板中环氧树脂热解规律进行了研究.考察了不同的热解终温(200～700 ℃)、升温速率(5～30 ℃/min)、真空度(以压力表征,3～30 kPa)及保温时间(10～150 min)对热解产物产率的影响.实验结果表明,热解终温是影响热解油产率最重要的因素;选择适当的热解终温(400～550 ℃)、升温速率(15～20 ℃/min)、真空度(15 kPa)及保温时间(30 min)有利于提高热解油产率.