埃洛石负载硫脲及其甲醛捕捉效果

研究了一种新型甲醛捕捉剂的制备方法及其除醛性能,用尿素插层埃洛石纳米管(HNTs),扩大其层间距,提高负载量,并通过真空负载制备埃洛石/尿素/硫脲纳米复合物.同时,将制备的纳米复合物分别在溶液和空气中测试吸附甲醛的效果,并通过紫外分光光度法和4-氨基-3-联氨-5-巯基-1,2,4-三氮杂茂(AHMT)显色法结合RGB取色法测试其对甲醛的吸附效果.结果表明,尿素能插层活化埃洛石纳米管,使其层间距由0.720 nm增加到1.070 nm,从而使硫脲负载量达到27.41%;埃洛石/尿素/硫脲在甲醛水溶液中吸附甲醛的过程符合Freundlich等温吸附模型;纳米复合物在甲醛水溶液中的除醛率可达60%,随着添加量的增加,埃洛石/尿素/硫脲纳米复合物对甲醛的吸附效果逐渐增强.     

污水处理厂对蛔虫卵的处理效果评价研究——以常州市为例

为了解城市污水处理厂对蛔虫卵的处理效果,利用改良的Bailenger方法,对常州市5家污水处理厂接纳污水和排放尾水蛔虫卵浓度进行检测.结果表明:以处理生活区污水为主污水处理厂接纳污水蛔虫卵含量最高,常州市武进城区污水处理厂,平均值93.33个/L;以处理工业区污水为主蛔虫卵含量最低,常州市戚墅堰污水处理厂,平均值13个/L;5家污水处理厂排放尾水蛔虫卵数量均能达到国家标准,蛔虫卵去除率基本可达100％.     

中国台湾地区环境监测市场化经验

介绍了中国台湾地区环境监测市场化的现状、体制机制、资质认定等方面情况,总结了台湾地区对社会化环境检测机构采取的许可证管理、监管平台建设、严格日常监管等方面的有效经验。     

抚仙湖、星云湖与杞麓湖营养状态演变及突变分析

为科学评价抚仙湖、星云湖和杞麓湖(简称三湖)营养状态及其变化趋势,基于三湖1991-2015年水质数据,采用综合营养状态指数法评价其富营养化水平,通过Mann-Kendall(Sneyers)方法判识三湖富营养化趋势及突变时间。结果表明:三湖都存在水质恶化现象,其综合营养状态指数及各分项指数均呈变差趋势,表征其营养物质在增加。三湖的营养化水平和演变时间存在显著差异,抚仙湖处于贫营养,星云湖由中营养转变为富营养,杞麓湖表现为中度-重度富营养化;抚仙湖和杞麓湖分别在2004、2011年出现突变点,星云湖自2000年后综合营养状态指数显著增加。基于三湖营养状态演变及趋势,结合变化特征及相关情况的讨论,提出对抚仙湖的管理应减少农业化肥和农药排放,对星云湖和杞麓湖的管理应削减高污染工矿企业排放等。     

Distribution,sources, and ecological risk assessment of HCHs and DDTs in water from a typical coal mining subsidence area in Huainan,China

Environmental Science and Pollution Research - Coal mining subsidence areas are a special and widespread ecosystem in China and many developing countries in the world. However, limited research has...     

Coexistence of antibiotic resistance genes,fecal bacteria,and potential pathogens in anthropogenically impacted water

Environmental Science and Pollution Research - Microbial indicators are often used to monitor microbial safety of aquatic environments. However, information regarding the correlation between...     

Comparative investigation of toxicity induced by UV-A and UV-C radiation using Allium test

Organisms are increasingly exposed to ultraviolet (UV) rays of sunlight, due to the thinning of the ozone layer and its widespread use in sterilization processes, especially against the SARS-CoV-2 virus. The present study was conducted with the purpose of evaluating the damages of UV-A and UV-C radiations in Allium cepa L. roots. The effects of two different types of UV on some physiological, biochemical, cytogenotoxic, and anatomical parameters were investigated in a multifaceted study. Three groups were formed from Allium bulbs, one of which was the control group. One of the other groups was exposed to 254 nm (UV-C) and the other to 365 nm (UV-A) UV. Growth retardation effect of UV was investigated with respect to germination percentage, total weight gain, and root elongation, while cytogenotoxicity arisen from UV exposure was analyzed using mitotic index (MI) and chromosomal aberration (CA) and micronucleus (MN) frequency. Oxidative stress due to UV application was investigated based on the accumulation of malondialdehyde (MDA) and the total activities of superoxide dismutase (SOD) and catalase (CAT) enzymes. Also, anatomical changes induced by UV-A and UV-C were analyzed in root meristematic cells. UV treatments caused significant reductions in growth-related parameters. Both UV treatments caused a significant increase in MDA levels and induction of SOD and CAT enzymes in root meristematic cells. A decrease in MI and an increase in the frequency of MN and CAs were observed in root tip cells, indicating the cytogenotoxic effect of UV application. Anatomical damages such as epidermis cell damage, cortex cell damage, necrotic zones, giant cell nucleus, and indistinct transmission tissue occurred in cells exposed to UV. All of the physiological, biochemical, cytogenetic, and anatomical damages observed in this study were more severe in cells treated with UV-C compared to UV-A. This study suggested that UV exposure triggered growth inhibition, cytogenotoxicity, oxidative stress, and meristematic cell damages in A. cepa roots depending on the wavelength.

     

Study on mechanical properties and microstructure of recycled fine aggregate concrete modified by Nano-SiO2

Journal of Material Cycles and Waste Management - In this study, the effects of different contents of Nano-SiO2 (NS) on a slump, compressive strength, splitting tensile strength, flexural strength,...     

Vertical distribution and temporal evolution of formaldehyde and glyoxal derived from MAX-DOAS observations: The indicative role of VOC sources

Formaldehyde (HCHO) and glyoxal (CHOCHO) are important oxidization intermediates of most volatile organic compounds (VOCs), but their vertical evolution in urban areas is not well understood. Vertical profiles of HCHO, CHOCHO, and nitrogen dioxide (NO₂) were retrieved from ground-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations in Hefei, China. HCHO and CHOCHO vertical profiles prefer to occur at higher altitudes compared to NO₂, which might be caused by the photochemistry-oxidation of longer-lived VOCs at higher altitudes. Monthly means of HCHO concentrations were higher in summer, while enhanced amounts of NO₂ were mainly observed in winter. CHOCHO exhibited a hump-like seasonal variation, with higher monthly-averaged values not only occurred in warm months (July-August) but also in cold months (November-December). Peak values mainly occurred during noon for HCHO but emerged in the morning for CHOCHO and NO₂, suggesting that HCHO is stronger link to photochemistry than CHOCHO. We further use the glyoxal to formaldehyde ratio (GFR) to investigate the VOC sources at different altitudes. The lowest GFR value is almost found in the altitude from 0.2 to 0.4 km, and then rises rapidly as the altitude increases. The GFR results indicate that the largest contributor of the precursor VOC is biogenic VOCs at lower altitudes, while at higher altitudes is anthropogenic VOCs. Our findings provide a lot more insight into VOC sources at vertical direction, but more verification is recommended to be done in the future.     

Spectroscopic characterization and photochemistry of the Criegee intermediate CF3C(H)OO

Criegee intermediates (CIs), also known as carbonyl oxide, are reactive intermediates that play an important role in the atmospheric chemistry. Investigation on the structures and reactivity of CIs is of fundamental importance in understanding the underlying mechanism of their atmospheric reactions. In sharp contrast to the intensively studied parent molecule (CH₂OO) and the alkyl-substituted derivatives, the knowledge about the fluorinated analogue CF₃C(H)OO is scarce. By carefully heating the triplet carbene CF₃CH in an O₂-doped Ar-matrix to 35 K, the elusive carbonyl oxide CF₃C(H)OO in syn- and anti-conformations has been generated and characterized with infrared (IR) and ultraviolet-visible (UV-vis) spectroscopy. The spectroscopic identification is supported by ¹⁸O-labeling experiments and quantum chemical calculations at the B3LYP/6-311++G(3df,3pd) and MP2/6-311++G(2d,2p) levels. Upon the long-wavelength irradiation (λ > 680 nm), both conformers of CF₃C(H)OO decompose to give trifluoroacetaldehyde CF₃C(H)O and simultaneously rearrange to the isomeric dioxirane, cyclic-CF₃CH(OO), which undergoes isomerization to the lowest-energy carboxylic acid CF₃C(O)OH upon UV-light excitation at 365 nm. The O₂-oxidation of CF₃CH via the intermediacy of CF₃C(H)OO and cyclic-CF₃CH(OO) might provide new insight into the mechanism for the degradation of hydro-chlorofluorocarbon CF₃CHCl₂ (HCFC-123) in the atmosphere.