Occurrence, polarity and bioavailability of dissolved organic matter in the Huangpu River, China

Dissolved organic matter （DOM） plays an important role in biogeochemical cycles in aquatic ecosystem. To investigate the characteristics of DOM in Huangpu River {the last tributary of the Yangtze River）, surface water samples were collected along the river from December 2011 to June, 2013. The concentrations of dissolved organic carbon （DOC）, the absorbance and fluorescence spectrum of DOM in water samples were measured. Fluorescent DOM in the Huangpu River was decomposed into four components by the parallel factor analysis （PARAFAC）, including one humic-like substance and three protein-like substances. It showed that high spatial variability of DOC concentration was observed in the upstream water compared to the downstream water, and so did the absorbance coefficients of chromophoric dissolved organic matter and the total fluorescence intensities of different PARAFAC components of DOM. Furthermore, there was a large difference between the polarity and bioavailability of DOM in the Huangpu River. Polar compounds dominated tyrosine-like component of fluorescent DOM in all seasons. Tryptophan-like and humic-like substances had more polar fraction in summer and autumn than those in winter, while aromatic protein-like materials had the highest polar fraction in winter. Almost all of fluorescent DOM components were refractory in spring, while less than 20% of fluorescent DOM in average were biodegradable within 4 weeks in other seasons. We concluded that the spatial variation in the abundance of DOM in the Huangpu River is mainly affected by the water discharges from the Hangjiahu Plain and the seasonal difference in polarity and bioavailability of DOM is largely determined by its origins.     

A toxicity-based method for evaluating safety of reclaimed water for environmental reuses

A large quantity of toxic chemical pollutants possibly remains in reclaimed water due to the limited removal efficiency in traditional reclamation processes. It is not enough to guarantee the safety of reclaimed water using conventional water quality criteria. An integrated assessment method based on toxicity test is necessary to vividly depict the safety of reclaimed water for reuse. A toxicity test battery consisting of lethality, genotoxicity and endocrine disrupting effect was designed to screen the multiple biological effects of residual toxic chemicals in reclaimed water. The toxicity results of reclaimed water were converted into the equivalent concentrations of the corresponding positive reference substances（EQC）. Simultaneously, the predicted no-effect concentration（PNEC） of each positive reference substance was obtained by analyzing the species sensitivity distribution（SSD） of toxicity data. An index ＂toxicity score＂ was proposed and valued as 1, 2, 3, or 4 depending on the ratio of the corresponding EQC to PNEC. For vividly ranking the safety of reclaimed water, an integrated assessment index ＂toxicity rank＂ was proposed, which was classified into A, B, C, or D rank with A being the safest. The proposed method was proved to be effective in evaluating reclaimed water samples in case studies.     

Enhanced anaerobic fermentation with azo dye as electron acceptor： Simultaneous acceleration of organics decomposition and azo decolorization

Accumulation of hydrogen during anaerobic processes usually results in low decomposition of volatile organic acids（VFAs）. On the other hand, hydrogen is a good electron donor for dye reduction, which would help the acetogenic conversion in keeping low hydrogen concentration. The main objective of the study was to accelerate VFA composition through using azo dye as electron acceptor. The results indicated that the azo dye serving as an electron acceptor could avoid H2 accumulation and accelerate anaerobic digestion of VFAs. After adding the azo dye, propionate decreased from 2400.0 to 689.5 mg/L and acetate production increased from 180.0 to 519.5 mg/L. It meant that the conversion of propionate into acetate was enhanced. Fluorescence in situ hybridization analysis showed that the abundance of propionate-utilizing acetogens with the presence of azo dye was greater than that in a reference without azo dye. The experiments via using glucose as the substrate further demonstrated that the VFA decomposition and the chemical oxygen demand（COD） removal increased by 319.7 mg/L and 23.3% respectively after adding the azo dye. Therefore, adding moderate azo dye might be a way to recover anaerobic system from deterioration due to the accumulation of H2 or VFAs.     

负载型纳米金属材料的最新研究进展

纳米金属材料因具有许多优异的特性,具有日益广阔的应用前景。负载型纳米金属相对于纯纳米金属材料具有稳定性高,易回收利用,无毒害性等优点,其制备和应用成为目前研究的热点之一。负载型纳米金属材料的制备方法很多,目前国内外学者通过大量的实验研究,总结出了一些比较成熟的,效果较理想的负载方法。因载体对负载方法的选择影响较大,文章着重介绍了以膨润土、活性炭、碳纳米管、氧化物和有机高分子类为载体的负载方法,引用国内外学者的实验成果,对制得的负载型纳米金属材料的形貌,粒径等特性进行描述。负载型纳米金属材料的应用广泛,着重描述了近年来其在环境治理和水生态保护方面的应用进展,对难降解的有机卤代物,有机染料和重金属以及硝酸盐类等的处理效果进行研究。最后提出了纳米金属材料在投入应用中应该解决的问题和展望。     

根际微生物对土壤有机物修复现状和发展

由于耕种需要、污灌、垃圾渗滤液、环境事故等原因大量的有机污染物进入土壤。因为良好的环境效益、社会效益和经济效益,利用植物修复有机物污染土壤已经成为国内外研究的重点和热点。在分析植物和根际微生物作用关系及其对有机物污染修复作用机理基础上,进一步探讨了植物和根际微生物对有机污染物的修复原理、修复效果和修复途径以及植物和根际微生物选择机理。最后根据目前研究的热点和土壤污染的特点,全面阐述了土壤有机物污染利用根际微生物进行修复的发展前景和发展趋势。     

石油类污染物在黏性土壤中的垂直分布规律

为了查明石油类污染物在黏性土壤中的垂直分布规律,本文选择某机械加工厂中机床下润滑油长期滴漏处为研究对象,研究了润滑油穿越地面混凝土层后在黏性土层中的分布特征,并结合土壤性质研究了该场地特征污染点在土壤0.2~3.0m深度范围内总石油烃(TPH)和挥发性有机物(VOCs)的垂直分布规律,以及土壤性质与土壤中TPH、VOCs含量的关系。结果表明:在工业企业石油类污染场地,污染物会透过素填土迁移进入较深层土壤;若地表污染源没有消除或刚停止持续污染,则TPH在表层素填土(0~0.5m)中含量较高,在浅层素填土(0.6~1.0m)中含量较低,而素填土中VOCs含量较低;在黏性土层中,大量TPH和VOCs会被吸附于在土层上方,且污染物浓度随土壤深度的增加显著降低。     

东海赤潮生消期典型断面颗粒有机物的垂直分布特征及影响因素

依据2011年3~5月对东海赤潮高发区典型断面Za的8次调查资料,研究了该海域在赤潮生消期颗粒有机物的垂直分布特征及变化,并对其影响因素进行了初步探讨。结果表明,赤潮爆发前颗粒有机物浓度高值中心主要集中在近岸海区,主要受陆源输入和沉积物再悬浮的影响,外海受少量浮游植物活动影响出现次高值区。赤潮爆发期,颗粒有机物浓度的高值区由近岸转为外海,浮游植物的活动成为影响颗粒有机物分布的主要因素。垂直方向上,赤潮爆发前由于沉积物再悬浮的影响,底层出现最大值,表层次之,中层最低。而赤潮爆发期,由于浮游植物活动的影响,表中层最高,赤潮爆发前后颗粒有机物与叶绿素的含量整体上呈上升趋势。     

挥发性有机污染物(VOCs)治理进展及发展前沿思考

本文介绍了近年国内外在治理可挥发性有机化合物的研究进展,并对吸附与催化技术,低温等离子体-光催化技术等几种先进的处理技术最新发展作了较全面的综述,并对发展前景进行展望。     

水体底泥及岸边土壤有机无机复合体对磷吸附特征对比

以长春市新立城水库底泥及岸边土壤为研究对象,利用平衡吸附法研究底泥、土壤及二者有机无机复合体(砂粒、粉粒和粘粒)对磷的吸附热力学和动力学特征,并探讨底泥和土壤各级复合体对磷的吸附贡献,以期探明底泥和土壤对磷的富集规律.结果表明,底泥和土壤对磷的吸附热力学均符合Langmuir方程和Freundlich方程,且底泥对磷的理论最大吸附量约是土壤的3倍.底泥及土壤粘粒复合体对磷的吸附热力学符合Langmuir方程和Freundlich方程,粉粒及砂粒复合体对磷的吸附符合Henry方程.粘粒复合体对磷的吸附量均大于粉粒复合体,而粉粒复合体均大于砂粒复合体.底泥及土壤粘粒复合体对磷的吸附贡献约为60%,粉粒复合体对磷的吸附贡献稍大于砂粒复合体的吸附贡献.底泥、土壤及二者有机无机复合体对磷的吸附动力学符合一级动力学方程、Elovich方程和双常数方程,且均在24 h以内达到吸附平衡.研究结果表明,底泥与岸边土壤对磷的吸附具有相似的规律,且底泥及其复合体对磷的吸附能力均大于土壤,说明若磷素由于地表径流等因素由土壤进入到水体中,底泥对磷会有较强的吸附净化作用,即某种意义上底泥为河流磷素有效的"汇".     

南京北郊大气VOCs变化特征及来源解析

利用2011-03-01~2012-02-29南京北郊大气VOCs观测资料,对大气VOCs浓度变化特征和特征物比值差异展开研究,并应用PCA/APCS受体模型对不同季节VOCs来源进行了解析.结果表明,南京大气总VOCs体积混合比为43.52×10-9,其中烷烃占45.1%、烯烃占25.3%、炔烃占7.3%和芳香烃占22.3%.总VOCs体积混合比呈现夏季高,冬季低的季节变化.VOCs组分中烷烃在冬季最高,烯烃夏季最高,芳香烃春季最高,炔烃冬季最高.特征物比值(VOCs/乙炔)和T/B比值反映出观测点受周边工业区影响较大.VOCs源解析表明,主要来源来自工厂生产、机动车排放、燃料燃烧、生产活动挥发、溶剂使用和自然源.虽然有季节变化,但与工业生产活动相关的来源占大气VOCs 45%~63%,其次为机动车来源占34%~50%.