高盐工业废水人工湿地处理中植物的筛选

通过人工湿地中试实验,考察了芦苇、睡莲、水葱、狭叶香蒲和宽叶香蒲水生植物单元对经生化处理的石油和精细化工工业区的工业废水中盐含量较高、氮磷营养盐含量较低和化学需氧量(COD)含量较高的废水中污染物的去除情况,研究了在植物不同生长阶段系统中COD的去除同盐度之间的关系,探讨了盐度差异对植物生长状况的影响,为确定人工湿地适合的进水盐度,达到有效去除高含盐量工业废水中有机污染物提供依据。结果表明,芦苇、睡莲和狭叶香蒲3种植物单元内高含盐量工业废水中污染物的净化效果较水葱和宽叶香蒲单元的净化效果好:前3种植物单元内COD、生化需氧量(BOD)和总磷(TP)的去除率大约在38%、55%和62%左右,而水葱和宽叶香蒲2种植物单元内COD、BOD和TP的去除率大约在30%、36%和52%左右;系统中各个单元内总氮(TN)去除率都在85%以上。在植物的不同生长阶段,人工湿地系统中氯离子浓度与COD浓度之间的相关性存在差异:植物生长初期,系统中氯离子浓度与系统中COD浓度之间无显著相关性,而在植物生长旺期和末期,两者则成正相关关系。因此,需根据植物的生长阶段调整人工湿地的进水盐度。     

运城市水污染控制与污水资源化对策

水环境污染与水资源紧缺是制约运城市建设与发展的两大重要因素。分析了运城市水污染现状与特征,提出了通过调整产业结构与布局、建立与完善地方法规和政策支持体系、加强综合协调与监督管理、加大科技投入及完善市场化运行机制等手段和措施防治与控制运城市水污染,实现污水资源化。     

从拒绝《京都议定书》看美国政府环境外交意图

作为国际社会最具影响力的环境协约,《京都议定书》却被美国政府拒之门外,通过对美国近年来针对该协约的态度及对全球变暖问题的外交举措分析,可以看出,美国政府环境外交行为的意图主要体现在三个方面,即规避不利条款的束缚;设计和实施替代性方案;积极争取国际环境领域的领导地位。     

用于气态零价汞转化的催化剂研究

零价汞的高效去除是燃煤烟气汞污染控制过程中的关键环节。为了促进烟气中的零价汞转化为易于去除的氧化态汞,分别考察了在有HCl存在时,几种过渡金属氧化物(Cu、Fe、Mn、Co和Zr)对零价汞氧化的催化作用,以筛选出性能较好的催化组分;为提高催化剂的抗SO2性能,分别尝试了利用几种金属元素(Sr、Ce、W和Mo)对催化剂进行掺杂改性的方法。结果表明,锰氧化物的催化作用最好,其最佳使用温度在573 K左右;SO2对零价汞的催化氧化有明显抑制作用,在无SO2及1 400 mg/m3SO2时锰催化剂对零价汞催化氧化效率分别为93%和78%。而Mo改性的锰氧化物催化剂的抗硫性能大幅提高,在1 400 mg/m3SO2存在的情况下其对零价汞的催化氧化效率可达到90%以上,较其他改性元素高。     

Characteristics of oxytetracycline sorption and potential bioavailability in soils with various physical-chemical properties

Veterinary antibiotics are widely used for disease treatment, prevention and animal growth promoting. Frequent detection of veterinary antibiotics in environments, caused by land application of untreated or even treated antibiotics-containing animal wastes, has posed the growing concern of their adverse effect on natural ecosystems. Oxytetracycline (OTC) is one of the most widely-used veterinary antibiotics in livestock industry. OTC present as a cation, zwitterions, or net negatively charged ion in soils complicates predicting its sorption characteristics and potential bioavailability and toxicity. This study was to identify soil properties influencing OTC sorption and its subsequent bioavailability in five soils with various physical-chemical properties. A solution used to determine bioavailable analytes in soils and sediments, 1 M MgCl₂ (pH 8.5), was chosen to desorb the potentially bioavailable fraction of OTC sorbed onto soils. Our results demonstrated that soils with higher illite content and permanent cation exchange capacity have higher OTC sorption capacity, but increase the availability of sorbed OTC indicated by higher release of sorbed OTC from soils into aqueous phase in 1 M MgCl₂ (pH 8.5). Reversely, soil organic matter (SOM), clay, kaolinite, variable cation exchange capacity, DCB-Fe and -Al have lower OTC sorption capacity, but decrease the release of sorbed OTC from soils into 1 M MgCl₂. These findings indicate that SOM and clay greatly influence OTC adsorption and potential availability. This study contributes significantly to our understanding of the potential bioavailability of sorbed OTC and the effects of soil properties on OTC sorption behaviors in soils.     

Polybrominated diphenyl ethers in soils of the modern Yellow River Delta, China: occurrence, distribution and inventory

The Yellow River is the second largest river in China. In this study, the levels of polybrominated diphenyl ethers (PBDEs) in the modern Yellow River Delta (mYRD) were firstly reported. Twenty PBDE congeners in soil/sediment samples from mYRD were measured. The total PBDE concentrations ranged from non-detectable to 18 257 ng kg⁻¹ with a mean value of 836 ng kg⁻¹. BDE-209 was the dominant congener, accounting for ∼86.1-99.5% of the total PBDEs. The congener profiles of PBDEs with higher abundances of BDE-153 and BDE-183 were similar to those in sediment of the Bohai Sea, indicating that they shared similar sources. The concentrations and congener patterns varied among different regions. Higher levels of PBDEs were found in the middle area (MA), and more complicated congener compositions were also observed in the MA, whereas lower levels of PBDEs were found in the modern course (MC) and the old course (OC). Much more PBDEs were detected in the top layer (TL) soil where more congeners were also held compared to lower soil layers, implying that more PBDEs were emitted into this area in recent years/decades. Organic matter controlled the PBDE distribution in the soil. Soil in this area might be a source of BDE209 for the Bohai Sea.     

Toxicity of lead on Ceriodaphnia dubia in the presence of nano-CeO(2) and nano-TiO(2)

Although engineered nanoparticles (NPs) could negatively impact environmental organisms, the synergistic effect of NPs and other toxic substances, which could be more significant than that of NP alone, have seldom been examined. The effect of two common NPs, nano-CeO₂ and nano-TiO₂, on the toxicity of Pb was evaluated using Ceriodaphnia dubia (C. dubia) as the model organism. Standard EPA procedures were followed in the toxicity evaluation. The toxicity of bare NPs (without Pb) was first evaluated and safe doses (levels without causing lethal effect) of NPs were used in the synergistic studies. It was found that the overall toxicity of Pb in the system containing NPs was greater than that of Pb alone, as indicted by the reduced median lethal concentration (LC₅₀) of soluble Pb. The sorption of Pb onto the NP, and the uptake of NPs in the gastrointestinal tract of C. dubia were validated. Therefore, the uptake of Pb-loaded NPs increased the exposure of C. dubia to Pb, resulting in the enhanced toxicity. Reducing the solution pH could shift Pb speciation and enhance the overall toxicity of Pb, with or without the presence of NPs.     

Remediation of polycyclic aromatic hydrocarbon (PAH) contaminated soil through composting with fresh organic wastes

Introduction  

Composting may enhance bioremediation of PAH-contaminated soils by providing organic substrates that stimulate the growth of potential microbial degraders. However, the influence of added organic matter (OM) together with the microbial activities on the dissipation of PAHs has not yet been fully assessed.