广州市白云山降水的化学特征及源解析

以2006年广州市白云山降水监测资料为基础,对其降水样品的化学特征进行了分析。结果表明,白云山降水样品pH值分布为3.04—6.41,雨量加权pH平均值为4.26,酸雨频率为70.2％,降水中的主要阳离子是Ca^2＋和NH^＋4分别占阳离子总量的46.4％和17.5％;主要阴离子为SO^2-4和NO^-3,分别占阴离子总量的59.0％和19.9％。相对酸度（FA）和中和因子（NF）计算结果表明,约有84.7％的降水酸度被碱性成分Ca^2＋和NH^＋4中和。利用富集系数方法,计算结果表明SO^2-4和NO^-3主要来源于人类活动,而Ca^2＋和K^＋主要来源于岩石／土壤风化。     

Response of microcystis to copper stress: do phenotypes of microcystis make a difference in stress tolerance?

To elucidate the role of phenotype in stress-tolerant bloom-forming cyanobacterium Microcystis, two phenotypes of M. aeruginosa - unicellular and colonial strains were selected to investigate how they responded to copper stress. Flow cytometry (FCM) examination indicated that the percents of viable cells in unicellular and colonial Microcystis were 1.92-2.83% and 72.3-97.51%, respectively, under 0.25 mgl(-1) copper sulfate treatment for 24h. Upon exposure to 0.25 mgl(-1) copper sulfate, the activities of antioxidative enzyme, such as superoxide dismutase (SOD) and catalase (CAT), were significantly increased in colonial Microcystis compared to unicellular Microcystis. Meanwhile, the values of the photosynthetic parameters (F(v)/F(m), ETR(max), and oxygen evolution rate) decreased more rapidly in unicellular Microcystis than in colonial Microcystis. The results indicate that colonial Microcystis has a higher endurance to copper than unicellular Microcystis. This suggests that the efficient treatment concentration of copper sulfate as algaecides will be dependent on the phenotypes of Microcystis.     

省域高速公路交通应急救援联动机制探讨

在系统分析省域高速公路应急救援组织体系存在问题的基础上,通过广泛调研和系统研究,结合我国国情,提出省域高速公路交通应急救援的组织指挥体系、可靠联动模式、运行机制、联动保障、技术路线等方案与措施。建立了基于领导机构、办事机构、工作机构、专家组4个层次的救援组织指挥体系,构建了高速公路交通应急救援的协调管理的基本机制,设计了对应协调管理基本机制的联动处置流程,并提出建设先进的高速公路交通应急救援调度信息中心的具体内容,为建立高效、稳健的高速公路交通应急救援组织体系与联动机制提供科学依据。该方案与措施有助于统一协调指挥多个救援部门之间的工作,实现救援部门之间的信息共享,确保交通应急救援调度和协调管理工作的顺利实施。     

公路交通事故黑点成因的对应分析法

为了便捷获取公路事故黑点的形成原因,应用对应分析构建立事故黑点成因分析模型。该模型设立事故样本和事故影响因素之间的列联表,将列联表中影响变量的状态呈现于二维对应分析散点图中,以直观简洁的形式描述事故样本与影响因素之间的对应关系。进而设定相关系数判定对应分析模型的收敛性,应用点子排除法剔除特殊影响变量,增强了分析结果的鲁棒性。通过G205事故黑点路段(K954+50-K954+900)的实例分析表明,运用对应分析法所建立的模型与算法可以获得公路事故黑点形成的主要和次要因素,准确确定直接原因与根本原因的对应关系。     

Selected organochlorine pesticides (OCPs) in surface soils from three major states from the northeastern part of India

Eighty-two surface soil samples were collected from forest, grassland, tea estate, wildlife sanctuary, wetland, and roadside areas from the northeastern states of India, viz., Tripura, Manipur, and Assam. Thirteen different organochlorine pesticides (OCPs) were detected from background soils using gas chromatography electron capture detector. Manipur soils were found to be with higher concentration of dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs), and endosulfan followed by Tripura and Assam. The spearman correlation coefficient shows significant correlation between HCHs, DDTs, and endosulfan isomers (r ²?>?0.5 and p?<?0.05). Additionally, α-HCH, δ-HCH, o,p′-DDE, and endosulfan-sulfate shows good correlation with total organic carbon in soil (r ²?=?0.5, p?=?0.05), indicating that the soil organic matter could enhance adsorption of these compounds, also demonstrating that the present OCPs in the background soil were from similar source. Further principal component analysis evaluates that most of the higher volatile compounds where clustered together in soil. However, after comparing with different states of Indian soil samples, the concentrations of OCPs in the present study areas are much lower and comparable with background soil across the globe.     

Environmentally Friendly Oil-Modified Polyesters as Polymeric Plasticizers for Poly(vinyl chloride)

Oil-modified polyesters were synthesized to serve as polymeric plasticizers for PVC. A total of four polymeric plasticizers with different average molecular weights were prepared. Characterizations were done using Fourier-transformed infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and gel permeation chromatography. Some of the tests conducted on PVC films include thermal stability test using thermogravimetric analyser, determination of glass transition temperature (T_g), plasticizer migration and leaching resistance test, morphology study of plasticized PVC films using field emission scanning microscope, toxicity test, and tensile test. Owing to the plasticizing effect of the palm oil-based compound, T_g of the plasticized PVC has decreased to an average of 65 °C at 20 wt% loading. The polymeric plasticizer is also able to contribute positively to the thermal stability and mechanical properties of the PVC films. Some of the advantages of incorporating polymeric plasticizer with high molecular weight includes lower rate of leaching from plastic, and improved tensile strength and elongation at break. Besides, thermal stability of the plastic studied using Kissinger’s and Flynn–Wall–Ozawa’s approaches shows that PVC blended with high molecular weight oil-modified polyester is more thermally stable, evidenced by the increase in the activation energy of decomposition, E_d. Toxicity test using brine shrimp egg shows encouraging results, where the oil-based plasticizer is considerably less toxic compared to some of the commercial plasticizers.     

苏丹红I对小鼠卵巢的损伤作用及对Caspase-3和Ki-67表达的影响

苏丹红是一种人工合成偶氮染料,可引起肝脏及泌尿系统等多个脏器的肿瘤,但苏丹红对生殖系统的毒性研究较少。本研究以昆明小鼠为受试对象,探讨苏丹红I对小鼠卵巢组织Caspase-3和Ki-67表达的影响。将24只昆明小鼠随机分为:对照组、低剂量(60 mg·kg~(-1))、中剂量(120 mg·kg~(-1))、高剂量(240 mg·kg~(-1))4组,6只/组。胃灌4周,4周末处死。HE染色观察各组卵巢组织病理变化,免疫组化法检测卵巢组织Caspase-3和Ki-67表达,Real time PCR检测卵巢组织Caspase-3和Ki-67 m RNA表达,Western blotting检测卵巢组织中Ki-67及Caspase-3蛋白表达。与对照组比较,实验组卵巢中Caspase-3阳性细胞率显著升高(P0.05),而Ki-67阳性细胞率显著降低(P0.05),Real time PCR及Western blotting结果与免疫组化法结果一致。本实验发现苏丹红染毒后颗粒细胞的Caspase-3表达增加,且Caspase-3表达呈剂量依赖性,但Ki-67表达受到抑制。     

Insights into the mercury(II) adsorption and binding mechanism onto several typical soils in China

To better understand the Hg(II) adsorption by some typical soils and explore the insights about the binding between Hg(II) and soils, a batch of adsorption and characteristic experiments was conducted. Results showed that Hg(II) adsorption was well fitted by the Langmuir and Freundlich. The maximum adsorption amount of cinnamon soil (2094.73 mg kg^?1) was nearly tenfold as much as that of saline soil (229.49 mg kg^?1). The specific adsorption of Hg(II) on four soil surface was confirmed by X-ray photoelectron spectroscopy (XPS) owing to the change of elemental bonding energy after adsorption. However, the specific adsorption is mainly derived from some substances in the soil. Fourier transform infrared spectroscopy (FTIR) demonstrated that multiple oxygen-containing functional groups (O–H, C=O, and C–O) were involved in the Hg(II) adsorption, and the content of oxygen functional groups determined the adsorption capacity of the soil. Meanwhile, scanning electron microscopy combined with X-ray energy dispersive spectrometer (SEM–EDS) more intuitive revealed the binding of mercury to organic matter, metal oxides, and clay minerals in the soil and fundamentally confirmed the results of XPS and FTIR to further elucidate adsorptive phenomena. The complexation with oxygen-containing functional groups and the precipitation with minerals were likely the primary mechanisms for Hg(II) adsorption on several typical soils. This study is critical in understanding the transportation of Hg(II) in different soils and discovering potential preventative measures.     

Levels,distribution profile,and risk assessment of polychlorinated biphenyls (PCBs) in water and sediment from two tributaries of the River Chenab,Pakistan

The first study aimed to investigate the polychlorinated biphenyl (PCB) concentration level, spatial distribution pattern, and ecological risk assessment of water and sediment samples from two tributaries (Nullah Aik and Palkhu) of the River Chenab, Punjab Province, Pakistan. A total of 32 PCB congeners were analyzed, and PCB concentration in sediment and water samples ranged between 0.80 and 60 ng/g and 0.20 and 28 ng/L, respectively, where tetra-CBs and tri-CBs dominated over other studied PCB homologs. Dioxin toxicity equivalency (TEQ) was calculated and PCB-126 and PCB-169 showed the higher TEQ values compared with the WHO guidelines, and sediment samples were more toxic than the water samples. The results of the present study should be considered seriously by government authorities to take a proper action against unchecked discharge of contaminants in ecological integrities; otherwise, there may be drastic results in the near future.     

柴油机微粒中可溶性有机成分的真空干燥条件

柴油机碳烟颗粒(PM)中可溶性有机组分(SOF)含量是其重要的特性参数,而真空干燥法可方便、高效、可靠地分析颗粒SOF含量,对其干燥条件的探索具有重要的研究意义和应用价值。首先采用模拟的柴油机颗粒,分析不同的干燥条件对模拟SOF(柴油、润滑油)挥发率的影响规律,得出模拟的SOF分析的最佳干燥条件;在此基础上,探索了真实柴油机颗粒SOF分析的最佳干燥条件为:干燥温度220℃、干燥时间3 h、真空度98 kPa,得知SOF组分干燥的难易程度介于柴油和润滑油之间;同时,根据此干燥条件,分析了排气管末端采集的真实碳烟颗粒的SOF含量特性。