Enhanced adaptability of Sesbania rostrata to Pb/Zn tailings via stem modulation

Sesbania rostrata is renowned for its stem nodulation, but the role of stem nodulation in the root nodulation and adaptation of S.rostrata to Pb/Zn-enriched tailings environment has been poorly understood.We investigated the effects of inoculating (with stem nodule treatment) and non-inoculating (without stem nodule treatment) Azorhizobium caulinodans on the growth, root nodulation, and N fixation of S.rostrata grown on three different types of soil substrata: Pb/Zn tailings, garden soil amended tailings, and garden soil.The results showed that plant height, stem basal diameter, biomass, chlorophyll content, nitrogen content and N-accumulation per plant were 2.3%-4.9%, 2.2%-7.7%, 27.8%-72.2%, 17.1%-23.5%, 12.3%-34.2%, and 43.1%-131.2% higher in treatments with stem nodule than those without stem nodule for the same soil substrate, respectively.With respect to soil substrata, all the measurements had consistently higher values in tailings than in amended tailings and garden soil, indicating that the poorer the soil condition, the greater the contribution of stem nodule.In contrast, the number and fresh weight of root nodules on plants without stem nodule were 6.9-11.6 times and 5.8-29.0 times higher than those with stem nodule, respectively, especially with respect to the plants grew on Pb/Zn tailings.In general, stem nodulation favored plant growth and nitrogen fixation of S.rostrata, but suppressed root nodulation.With the ability of stem and root nodulation, S.rostrata can be used as a pioneer plant species for remediation of Pb/Zn tailings.     

Characterizing spatial distribution and sources of heavy metals in the soilsfrom mining-smelting activities in Shuikoushan,Hunan Province, China

The spatial variation of heavy metals in the soils in Shuikoushan mining-smelting area, Hunan Province, China, was investigatedusing multivariate and geo-statistic analysis. A total of 106 composite soil samples were collected in an area of about 100 km2.Concentrations of total As, Cd, Pb, Zn, Cu and Cr were measured using inductively coupled plasma mass spectrometry (ICP-MS).Arsenic and Pb were found to have a common source, indicating the same sources and spreading processes, such as aerosols andairborne particulates from smelting chimneys. Airborne sources from smelting chimneys contributed greatly to Cd in the area, whichdemonstrated the same dispersion pattern as As and Pb. However, two hot spots of Cd around smelters were possibly enlarged bywastewaters, demonstrating another important source of Cd in Shuikouhsan. Geo-statistic interpolated mapping demonstrated that hotspotsof Zn were only found proximal to the large smelters, suggesting that Zn primarily came from the chimneys of larger smelters.The major Cu hot-spots appeared closely to the tailing dam, indicating that weathering and leaching of tailings were the major sourcesof Cu contamination in Shuikoushan. Our findings indicated that airborne volatile particles and aerosols contributed the most to As,Cd, Pb, Zn and Cu contamination, while Cd and Cu may also derive from the discharge of wastewater from smelters and the leachingof tailings, respectively.     

Ecotoxicological effects of mixed pollutants resulted from e-wastes recycling and bioaccumulation of polybrominated diphenyl ethers in Chinese loach (Misgurnus anguillicaudatus)

To understand potential ecotoxicological effects of electrical and electronic equipment waste (e-waste) recycling and polybrominated diphenyl ethers (PBDEs) bioaccumulation in loaches, a semi-field experiment using Chinese loach (Misgurnus anguillicaudatus) as experimental fish was performed. Larval loaches were kept into net-cage for three months in an e-wastes recycling site and a reference site in Southeastern China. There was significant difference of the survival rate between the loaches from the e-wastes recycling site (27%, 19/70) and from reference site (70%, 49/70). Histopathological responses were also found in all the livers examined in loaches from the e-wastes recycling site. These results showed that mixed pollutants resulted from e-wastes recycling led to ecotoxicological effects on loaches. The bioaccumulation of polybrominated diphenyl ethers (PBDEs), the main pollutants in e-waste, in loaches was also studied in this e-wastes recycling site, the mean concentrations of total PBDEs in sediment was 6726.17 ng/g wet weight and in water samples was 4.08 ng/L (dissolved phase). BDE209 was the dominant congener in sediment and with relatively high concentration in water. Relatively low concentration of BDE209 (less than 0.01% of total PBDEs) and high concentration of BDE47 (up to 39.34% of total PBDEs) were detected in loaches.     

不同标准对城市土壤重金属质量分数的评价

对广州市某区城市土壤重金属污染现状进行调查,共采集土壤样品34个,分析样品中As,Hg,Cr,Cd,Ni和Pb的全量及有效态质量分数,探讨重金属元素全量和有效态质量分数之间的关系,并采用4种不同标准对结果进行了评价. 结果表明:研究区工业用地、城区和农村居住区的土壤已受到一定程度的重金属污染,且为2种或3种重金属元素的复合污染;As,Hg,Cr,Cd,Ni和Pb有效态质量分数平均值分别为0.09,0.004,0.09,0.18,0.40和32.80 mg/kg,Cd和Pb的有效态质量分数占全量的比例较高. 4种标准综合评价结果中,轻度、中度和重度污染样点数占样点总数的比例依次为国标(GB15618—1995)二级标准评价(62%)>有效态污染起始值评价(29%)>全量污染起始值评价(24%)>国标三级标准评价(21%).      

纳米ZnO对嗜热四膜虫的生态毒性研究

为评价纳米ZnO的生态安全性,研究了其对嗜热四膜虫(Tetrahymena thermophila)的水生生态毒性. 显微成像表明,嗜热四膜虫食物泡是摄取纳米ZnO的主要部位. 低ρ(纳米ZnO)对嗜热四膜虫的增殖具有促进作用(即“兴奋反应),其中100 mg/L时促进作用最明显,随着ρ(纳米ZnO)的进一步增加,其对嗜热四膜虫增殖的促进作用逐渐减弱. 随着时间的延长,“兴奋反应逐渐减弱. 纳米ZnO能降低嗜热四膜虫的超氧化物歧化酶活性,且ρ(纳米ZnO)越高,抑制效应越强. 纳米ZnO使嗜热四膜虫自由基清除能力下降,可能是其产生毒害作用的主要原因之一.      

基于微波辐射研究城市污水污泥脱水特性

选用沈阳市仙女河污水处理厂和北部污水处理厂污水污泥作为微波脱水试验物料,分析物料性质、辐射强度、辐射时间以及添加剂投入量等对污泥脱水率和有机质损失率的影响. 结果表明:污泥中水分含量高的脱水效果最好,经过微波处理后的污泥有机质含量仍较高;辐射时间是最主要的影响因素,在540 W下辐射2～5 min即可达到良好效果;在合适的辐射时间下540～900 W都能达到良好的脱水效果,但在900 W时有机质的损失率较大,达到65.64%;添加剂投入量对污泥脱水基本不起作用,但可改变污泥微波干燥后的性状. 同时,运用灰色关联分析得到决定微波试验运行系统的主次因素,最后建立了影响因素对污泥脱水率和有机质损失率的经验公式.      

长江口水体中PAHs的基本生态风险特征

通过对2007年4月24—30日采集于长江口水体7个不同采样点18个水样中的4种典型多环芳烃类化合物(PAHs)的浓度分析,依据3个基础营养级水平(藻、、鱼)的毒性效应〔L(E)C50和NOEC〕,采用欧盟适用于现有化学物质与新化学物质的风险评价技术指南(TGD)中的商值法对长江口水体中的萘、菲、蒽、荧蒽进行了生态风险评价. 结果表明,4种PAHs除蒽外的环境浓度/无影响浓度(PEC/PNEC)都小于1. 说明长江口水体中4种PAHs只有蒽存在一定生态风险,其他3种均未对长江口生态造成威胁.      

氨基酸对烷烃降解菌GS3C降解性能的影响

从广州石油化工总厂污水处理站旁的油泥混合物中分离筛选得到一株烷烃降解菌GS3C,从生理生化及16S rDNA基因扩增测序等方面进行了鉴定,并在振荡好氧培养条件下研究该菌的降解性能及酵母浸膏、碳源、氮源、维生素、水解酪蛋白等营养物对其降解的影响,同时考察不同氨基酸对降解的影响. 结果表明,该菌的16S rDNA基因扩增序列与Burkholderia cepacia的同源性为97%,初步断定该菌株属于洋葱伯克霍尔德氏菌(Burkholderia cepacia),酵母浸膏能促进其对正十六烷的降解,其主要因素为氨基酸对降解的促进作用. 谷氨酸、脯氨酸、赖氨酸、缬氨酸及亮氨酸的混合物对降解菌GS3C的代谢促进作用最好,其中赖氨酸与脯氨酸为关键的2种氨基酸.      

破碎聚氨酯硬泡时CFC-11的释放量和残留量

将聚氨酯硬泡在密闭室中破碎至不同粒径,低温加热后进行氧弹燃烧试验,利用气相色谱/质谱联用(GC/MS)定量每个过程中发泡剂CFC-11(CFCl₃)的释放量.结果表明:CFC-11释放量随破碎颗粒粒径的减小而增大,过4 mm筛的颗粒释放效果最佳,CFC-11释放量占其总量的67%;泡沫中w(CFC-11)为20%左右,其中77%的CFC-11包裹在泡孔中,23%被泡沫固相吸附;即使将泡沫过1 mm筛,部分未打破泡孔中仍有6%的CFC-11,当破碎粒径接近泡孔平均直径0.3～0.4 mm时,CFC-11释放量保持不变,吸附于泡沫固相中的CFC-11在破碎过程中很难释放.      

高砷煤燃烧影响下室内外空气砷含量特征

利用空气总悬浮物采样器和安德森颗粒物分级采样器,对陕西南部燃煤型砷中毒地区的室内外空气样品进行了采集和化学分析,探讨了室内外空气ρ(总砷)与煤w(砷)的关系,以及空气ρ(总砷)在不同粒径颗粒物中的分布特征. 结果表明:室内外空气ρ(总砷)均与煤w(砷)呈显著正相关,烤火间空气ρ(总砷)与煤w(砷)的相关系数(R)为0.80(P<0.01);室外空气ρ(总砷)平均值与当地煤w(砷)平均值的相关系数(R)为0.97(P<0.01);烤火间空气ρ(总砷)高峰主要出现在向煤炉添煤3 h后的旺火期,且旺火期的室内空气ρ(总砷)与空气ρ(粉尘)呈显著正相关(R0.74,P<0.05).与土木结构相比,砖混结构房屋有助于减少燃煤释放到空气中的砷在不同房间之间的扩散;室内不同房间之间、室外不同地点之间以及室内外的空气ρ(总砷)差异主要表现在颗粒物粒径小于2.1 μm的部分;天气状况对室内空气ρ(总砷)随颗粒物粒径的分布没有明显影响.