Transformation of tetrabromobisphenol A in the presence of different solvents and metals

Solvent-based separation method is presumably an efficient and environmentally beneficial approach for elimination of brominated flame retardants (BFRs) from waste electrical and electronic equipment (WEEE). The overall goal of this study was to evaluate possible effects of organic solvent on the behavior of BFRs during solvent-based processing of WEEE. We initiated a set of batch experiments for examining the rates and possible pathways of transformation of a representative BFR (tetrabromobisphenol A, TBBPA) using acetone, toluene, and methanol as the solvents. Our results showed that toluene and methanol had no effect on the transformation of TBBPA, but approximately 20% of TBBPA (100 mg L⁻¹) was transformed by acetone within 2 h at 50 °C. Analysis of the products with GC-MS showed that two high-molecular-weight products (MW = 586) were major products of the transformation reactions. The role of acetone as a reactant in the transformation of TBBPA was further validated with dueterated acetone. In addition, the effects of co-existing metals in WEEE (i.e., Zn, Cu, and Ni) on the transformation of TBBPA in the solvent systems were investigated. These metals tested were found to greatly enhance the rates of TBBPA transformation. The metal facilitated solvent reactions with TBBPA may lower the extractability of TBBPA by formation of larger and less soluble products, hence potentially increasing the cost for separating the chemical from WEEE.     

Comparison of homologous and heterologous formats in nanocolloidal gold-based immunoassays for parathion residue determination

The effectiveness of homologous and heterologous formats in a nanocolloidal gold-based immunoassay for pesticide residue determination was investigated. Parathion, one of the most toxic organophosphorus pesticides, was used as the target analyte. One-step homologous and heterologous test strips based on a nanocolloidal gold-labeled monoclonal antibody were developed for the rapid detection of parathion residues. The results showed that the heterologous format was more effective than the homologous format, being more sensitive, more specific to parathion and more tolerant of matrix interferences. The best competitive hapten was found to have a moderate heterology and the opposite electronic distribution to the immunizing hapten. The detection limits for parathion using the preferred heterologous strip were 1 μg/L in water samples and 5 μg/kg in soil and food samples.     

兼性厌氧菌群对湖滨带底泥有机污染物的降解效应

研究了兼性厌氧菌群不同接种量(1%(体积分数,下同)、5%、10%、20%、50%)下对太湖湖滨带底泥有机污染物的降解效果及微生物群落结构的影响。结果表明,与对照组相比,接种兼性厌氧菌群能显著提高总有机碳(TOC)、TN的降解率且降解率高,但是TP的降解率波动较大。补充实验证明接种菌液中大量的有机碳、氮源会引起样品中初始浓度升高,建议在使用接种菌液前进行3次无菌水冲洗。综合考虑接种兼性厌氧菌群对湖滨带底泥有机污染物的降解效果,确定其最佳接种量为10%。另外,接种兼性厌氧菌群后其菌群数量和菌活性都有显著提高而严格好氧菌、严格厌氧菌数量均无显著变化;第0天,微生物在接种量为10%时菌活性电子传递体系(ETS)最高。     

k-C*模型的人工湿地模拟研究

采用自由表面流人工湿地,对广东省中山市某小区对应段的河涌进行生态修复改造。基于k-C*模型的计算结果表明,在对现有河涌的面积的利用下,TP和NH4+-N的去除效果受到限制。采用多因素正交实验对模型的计算结果进行实验验证和分析,研究了4种植物、4种基质,分别在2、4、6和8 d水力停留时间(HRT)下对TP和NH4+-N的去除效果,得到影响TP和NH4+-N去除效果的因素主次顺序分别为基质→植物→HRT和基质→HRT→植物;各因素的最佳水平条件分别为:风车草、颗粒活性炭、4 d(HRT)。在最佳水平条件下进行实验,结果表明,TP和NH4+-N的浓度均可达到出水排放标准浓度指标。k-C*模型的计算值总是比实验值偏高,但两者之间的误差在一个数量级范围内。     

陶瓷印花废水处理的混凝剂及工艺条件

采用混凝剂聚合氯化铝（PAC）、聚丙烯酰胺（PAM）、聚合硫酸铁（PFS）对陶瓷印花废水进行混凝沉降处理,监测水样的吸光度、浊度、悬浮物,以脱色率、浊度去除率、悬浮物去除率评价混凝处理的效果。结果表明：PAC是陶瓷印花废水沉降处理的理想混凝剂;水样的吸光度、浊度、悬浮物随混凝剂用量增大和沉降时间延长而呈降低趋势,而脱色率、浊度去除率、悬浮物去除率随混凝剂和沉降时间的增大呈增大的趋势;PAC投加量为20mg／L,沉降时间约为24h,水样脱色率达到90．0％,而当PAC投加量达到100mg／L,沉降时间约为4h,陶瓷印花水的脱色率可达到96．0％。证明了药剂用量的增加与沉降时间的延长对混凝过程具有增效作用。     

Changes in Soil Particulate Organic Matter, Microbial Biomass, and Activity Following Afforestation of Marginal Agricultural Lands in a Semi-Arid Area of Northeast China

Afforestation of agricultural lands has been one of the major land use changes in China in recent decades. To better understand the effect of such land use change on soil quality, we investigated selected soil physical, chemical and microbial properties (0–15 cm depth) in marginal agricultural land and a chronosequence of poplar (Populus euramericana cv. ‘N3016’) plantations (5-, 10-, 15- and 20-years old) in a semi-arid area of Northeast China. Soil bulk density significantly declined after conversion of agricultural lands to poplar plantations. Soil total organic carbon (TOC) and nitrogen (TN) concentrations, microbial biomass C (MBC) and potential N mineralization rate (PNM) decreased initially following afforestation of agricultural lands, and then increased with stand development. However, soil metabolic quotient (qCO₂) exhibited a reverse trend. In addition, soil particulate organic matter C (POM-C) and N (POM-N) concentrations showed no significant changes in the first 10 years following afforestation, and then increased with stand age. These findings demonstrated that soil quality declined initially following afforestation of agricultural lands in semi-arid regions, and then recovered with stand development. Following 15 years of afforestation, many soil quality parameters recovered to the values found in agricultural land. We propose that change in soil quality with stand age should be considered in determining optimum rotation length of plantations and best management practices for afforestation programs.     

Emission factors and particulate matter size distribution of polycyclic aromatic hydrocarbons from residential coal combustions in rural Northern China

Coal consumption is one important contributor to energy production, and is regarded as one of the most important sources of air pollutants that have considerable impacts on human health and climate change. Emissions of polycyclic aromatic hydrocarbons (PAHs) from coal combustion were studied in a typical stove. Emission factors (EFs) of 16 EPA priority PAHs from tested coals ranged from 6.25 ± 1.16 mg kg^?1 (anthracite) to 253 ± 170 mg kg^?1 (bituminous), with NAP and PHE dominated in gaseous and particulate phases, respectively. Size distributions of particulate phase PAHs from tested coals showed that they were mostly associated with particulate matter (PM) with size either between 0.7 and 2.1 μm or less than 0.4 μm (PM_0.4). In the latter category, not only were more PAHs present in PM_0.4, but also contained higher fractions of high molecular weight PAHs. Generally, there were more than 89% of total particulate phase PAHs associated with PM_2.5. Gas-particle partitioning of freshly emitted PAHs from residential coal combustions were thought to be mainly controlled by absorption rather than adsorption, which is similar to those from other sources. Besides, the influence of fuel properties and combustion conditions was further investigated by using stepwise regression analysis, which indicated that almost 57 ± 10% of total variations in PAH EFs can be accounted for by moisture and volatile matter content of coal in residential combustion.     

基于因子分析法优选河流水体中氮浓度预测方法的研究

定量的河流水体中氮浓度预测方法有很多种,如何优选出预测精度较高的方法一直是学术界多年来致力于研究的重点。本研究采用因子分析法对预测方法的精度评价指标进行分析,并建立了预测方法精度的评价模型,对回归分析法、神经网络法、灰色系统法和增长率统计法4种水体氮浓度预测方法进行综合评估,优选出精度较高的河流水体氮浓度预测模型——BP神经网络预测模型。结果表明,此评估模型对类似研究具有一定的参考价值,能为选择出合适的河流水体氮浓度预测方法提供依据。     

脉冲电解法预处理酸性染料废水

研究了脉冲电解法预处理酸性偶氮类染料废水的处理效果,考察了不同工艺条件对废水COD去除率、脱色率和可生化性的影响。结果表明,脉冲电源峰值电压12 V,频率600 Hz,占空比50%的条件下电解40 min后,COD去除率可达59%,废水脱色率达91.4%,BOD5/COD由0.09提高至0.34。在相同条件下,脉冲电解法的电流效率是直流电解法的2倍左右。与现行常用的铁/碳反应床相比,脉冲电解法在成本上也具有一定的优势,应用前景较好。     

生物强化处理石油污染土壤理化性质和微生物学特性的纵向分布特征

采用原位强化生物修复技术对某区块石油污染土壤进行为期16个月的生物修复,考察了处置后污染土壤理化性质、微生物学特性以及石油烃组成的纵向分布特征。实验结果表明,经过修复后各土层的石油烃去除率是表层土IN-3(50.42%)中层土IN-2(23.54%)底层土IN-1(10.51%);IN-1处于缺氧环境,存在硫酸盐还原和反硝化作用,使得土壤pH值从7.86±0.03降低至7.27±0.03,土壤总氮从2.53±0.13 g/kg降低至0.77±0.04 g/kg;厌氧菌的种群数量是IN-1(10.43±0.71×104CFU/g)IN-3(6.74±0.39×104CFU/g)IN-2(5.15±0.42×104CFU/g),放线菌数量与石油烃含量显著负相关(r=-0.989,p=0.0110.05);IN-3对饱和份和芳香份的降解率最高,分别达到了70.27%和54.52%,远高于IN-2和IN-1;模拟蒸馏结果表明,IN-3正构烷烃得到了很大程度的去除,缺氧的IN-1对正构烷烃去除得较少;厌氧菌数量与胶质和沥青质去除率之间成正相关关系,对于污染源较为分散的污染区域,采用原位生物强化修复时可以考虑引入厌氧修复。