黄河中下游水体中多环芳烃的分布及来源

对小浪底至山东东明段黄河干、支流水、悬浮物和沉积物进行了采样分析.结果表明,干流水相∑15PAHs浓度范围为179～369ng/L,其中除焦巩桥外其它断面苯并(a)芘均超过国家饮用水标准;支流水相浓度均高于相应干流,尤其是富含低环PAHs的孟州一干渠对干流沉积相浓度有较大影响.与水相相比,悬浮、沉积相中PAHs检出种类较多,干流悬浮相∑13PAHs浓度范围为54～155μg/kg,且各环PAHs与悬浮相中TOC含量间存在一定正相关.干流沉积相∑13PAHs浓度范围为31～133μg/kg,其4、5、6环P     

水体颗粒物的粒径和组成对多环芳烃生物降解的影响

采用模拟实验方法,研究黄河水体颗粒物的粒径和组成对苯并[a]芘和的生物降解速率的影响及影响机制.结果表明,苯并[a]芘和在水/颗粒物混合体系的降解符合一级动力学规律,颗粒物的存在促进了二者的生物降解,并且中沙(7～25μm)的促进作用最大,细沙(<7μm)次之,粗沙(>25μm)最小.在中沙、细沙和粗沙体系中,苯并[a]芘的一级动力学常数分别为0.024 8d^-1、0.021 2d^-1、0.019 2d^-1,的一级动力学常数分别为0.028 8d^-1、0.026 1d^-1、0.021 8d^-1.其影响机制主要包括:①颗粒物的存在促进了体系中多环芳烃降解菌的增长,且中沙和细沙体系中微生物增长快于粗沙体系.②多环芳烃(PAHs)吸附于颗粒物表面,其解吸作用使得颗粒物附近PAHs的浓度相对较高,且由于微生物也主要生长于水/颗粒物界面,这样使得微生物和PAHs接触的机会增大.由于中沙和细沙体系中颗粒物对微生物和PAHs的吸附作用均远大于粗沙体系,因此使得中沙和细沙体系中PAHs的降解速率大于粗沙体系.另外,与中沙相比,细沙对PAHs的吸附作用更强,解吸相对困难,从而使细沙体系中PAHs的降解速率低于中沙体系.     

Protecting Sensitive Coastal Areas with Exclusion Booms during Oil Spill Events

Oil spills at sea remain a serious threat to coastal settlements and sensitive ecosystems. Although the impacts of spills are contingent upon a variety of environmental factors and the chemical composition of the oil itself, spill effects can be long lasting in the pelagic zone with broad impacts on sensitive bacterial, microbial, plant, and animal communities. Efforts to contain, deflect, protect, and mitigate the effects of oil are increasingly important, given the massive social, economic, and environmental fallout connected to large spills. The purpose of this paper is to provide geographic perspective for protecting coastal areas with exclusion booms during oil spill events. Specifically, we introduce a generalized, extendable, spatial optimization model that simultaneously minimizes spill effects on vulnerable shorelines and the total costs associated with dispatching booms. The multiobjective model is solved with a weighting method to produce a Pareto optimal curve that reveals how the costs and protection operations change under different priorities. A simulated tanker spill near Mobile Bay, AL, USA, is used as an illustrative example.

     

Physical origin for the nonlinear sorption of very hydrophobic organic chemicals in a membrane-like polymer film

Bioconcentration factor (BCF) is often assumed to be linearly associated with the octanol-water partition coefficient K(ow) for hydrophobic organic chemicals (HOCs). However, a large amount of data has suggested that the correlation between the logBCF and logK(ow) is curvilinear for HOCs. Similar curvilinear relationship has also been noticed for sorption of HOCs into poly(dimethyl)siloxane (PDMS), a polymer with cross-linked interior structures. So far no satisfactory explanation has been given to account for the deviation. In this study, we acquired additional experimental data to show that the curvilinear relationship between the log-based PDMS-coated fiber-water partition coefficient (logK(f)) and logK(ow) for polychlorinated biphenyls (PCBs) was indeed a reflection of the sorption process occurring in PDMS film other than experimental defects. The physical origin of the nonlinearity was pinpointed based on the theory of phase partitioning for HOCs. The linear relationship is observed if the solute molecule is considerably smaller than the size of a monomer unit of PDMS in that the Gibbs free energy required for cavity formation in PDMS is comparable to that in octanol. Higher free energy of cavity formation is needed to create sufficient free volume if the PCB molecular size is comparable to or larger than the monomer unit of PDMS. On the other hand, the free energy of cavity formation in octanol remains almost constant when this occurs, resulting in the observed curvilinear relationship. The proposed model adequately explains the observed data, as well as sheds lights into the physical origin of the steric interactions of large molecular size solute with the PDMS polymer network.     

Hyperaccumulating potential of Bidens pilosa L. for Cd and elucidation of its translocation behavior based on cell membrane permeability

Environmental Science and Pollution Research - Phytoremediation with the use of hyperaccumulating plant species to remove excess trace metals from contaminated soil and water is considered a...     

Immobilization of laccase by Cu2+ chelate affinity interaction on surface-modified magnetic silica particles and its use for the removal of 2,4-dichlorophenol

Magnetic Cu²⁺-chelated silica particles that employ polyacrylamide as a metal-chelating ligand were developed and used to immobilize laccase by coordination. The particles were characterized by scanning electron microscope and Fourier transform infrared spectroscopy. The preparation, the enzymatic properties of the immobilized laccase, and its catalytic capacity for 2,4-dichlorophenol degradation were systemically evaluated. The results showed that immobilized laccase exhibited maximum enzyme activity when it was immobilized for 1 h at a pH of 4.0 and a temperature of 5 °C. The optimum laccase dose was 20 mg/g of carrier. In comparison to free laccase, the immobilized laccase had better acid adaptability and thermal stability. Higher activity was observed for immobilized laccase at a pH range of 2.0 to 3.5 and temperatures from 25 to 40 °C. The immobilized laccase that was prepared for this work exhibited a good catalytic capacity for removing 2,4-dichlorophnol from aqueous solutions.     

闽江福州段沉积物中多环芳烃的空间分布异质性研究

多环芳烃(PAHs)是环境中一类典型的持久性有机污染物,为探明PAHs在闽江福州段沉积物中的空间分布规律,采用传统统计学和地统计学相结合的方法对PAHs的空间异质性进行了研究.结果表明,PAHs含量变异系数(CV)在39%～90%之间,属于中等强度变异.3环PAHs含量的块金值与基台值之比[C0/(C+C0)]为0.307,具有中等强度的空间相关性,其余不同环数PAHs以及PAHs总量的C0/(C+C0)值都小于0.25,具有强烈的空间相关性.低环PAHs的分维数D值高于高环PAHs,空间异质性较高.3环及3环以上PAHs的Moran’s I系数随距离的增大而下降,且在0～25.0 km之间其空间自相关性随间隔距离的增大而减弱;而Moran’s I系数分析结果进一步说明了2环PAHs的空间变异特征的复杂性.受到水流影响,PAHs含量在南-北方向的半方差函数值与其它方向有所不同,但在东北-西南、东南-西北和东-西方向上的半方差函数值重合性较好,近似各向同性.用交叉验证法检验的结果表明,普通克里插值法能够很好地预测闽江福州段沉积物中PAHs的空间分布情况,PAHs含量沿水流流向大致呈下降的趋势.     

The association between maternal perfluoroalkyl substances exposure and early attention deficit hyperactivity disorder in children: a systematic review and meta-analysis

Environmental Science and Pollution Research - Some studies have shown that maternal exposure to perfluoroalkyl substances (PFASs) may be associated with early attention deficit hyperactivity...     

生物体内甲基汞检测方法的研究进展

无机汞离子容易在微生物的作用下转化为毒性很强的甲基汞,甲基汞具有亲脂性易在生物体内积累,并通过食物链传递对人体健康产生严重危害。因此研究和建立生物体内甲基汞含量快速、准确的检测方法至关重要。文中概述了生物体内甲基汞的主要检测技术和方法,其中气相色谱-原子荧光光谱法(GC-AFS)、高效液相色谱-电感耦合等离子体质谱联用法(HPLC-ICP/MS)和高效液相色谱-原子荧光光谱法(HPLCAFS)是三种最常用的检测方法。同时,介绍了处于研究阶段的化学荧光探针检测方法,并对生物体内甲基汞的检测技术发展方向进行了展望。     

火球热辐射改进计算模型

为对火球热辐射影响范围进行合理的计算和危险后果进行合理评价,借鉴点源模型和计算流体力学CFD思想,建立了火球热辐射改进计算模型,并与点源模型进行了对比。结果表明:改进模型比传统的点源模型计算结果偏大,特别是距离火球较近处。随着半径的增加,2种模型的计算结果趋于统一。当测量点的半径大于火球半径的2倍时,可以使用点源模型进行热辐射量的计算,满足工程精度要求;在近火球位置,点源模型精度较差,须用改进模型进行计算。建立的改进计算模型可以实现火球热辐射的快速计算,是有效、可行的。