Comparative phototoxicity of nanoparticulate and bulk ZnO to a free-living nematode Caenorhabditis elegans: the importance of illumination mode and primary particle size

The present study evaluated phototoxicity of nanoparticulate ZnO and bulk-ZnO under natural sunlight (NSL) versus ambient artificial laboratory light (AALL) illumination to a free-living nematode Caenorhabditis elegans. Phototoxicity of nano-ZnO and bulk-ZnO was largely dependent on illumination method as 2-h exposure under NSL caused significantly greater mortality in C. elegans than under AALL. This phototoxicity was closely related to photocatalytic reactive oxygen species (ROS) generation by the ZnO particles as indicated by concomitant methylene blue photodegradation. Both materials caused mortality in C. elegans under AALL during 24-h exposure although neither degraded methylene blue, suggesting mechanisms of toxicity other than photocatalytic ROS generation were involved. Particle dissolution of ZnO did not appear to play an important role in the toxicity observed in this study. Nano-ZnO showed greater phototoxicity than bulk-ZnO despite their similar size of aggregates, suggesting primary particle size is more important than aggregate size in determining phototoxicity.     

Nitrogen concentrations in mosses indicate the spatial distribution of atmospheric nitrogen deposition in Europe

In 2005/6, nearly 3000 moss samples from (semi-)natural location across 16 European countries were collected for nitrogen analysis. The lowest total nitrogen concentrations in mosses (<0.8%) were observed in northern Finland and northern UK. The highest concentrations (≥1.6%) were found in parts of Belgium, France, Germany, Slovakia, Slovenia and Bulgaria. The asymptotic relationship between the nitrogen concentrations in mosses and EMEP modelled nitrogen deposition (averaged per 50 km × 50 km grid) across Europe showed less scatter when there were at least five moss sampling sites per grid. Factors potentially contributing to the scatter are discussed. In Switzerland, a strong (r² = 0.91) linear relationship was found between the total nitrogen concentration in mosses and measured site-specific bulk nitrogen deposition rates. The total nitrogen concentrations in mosses complement deposition measurements, helping to identify areas in Europe at risk from high nitrogen deposition at a high spatial resolution.     

The performance of nature reserves in capturing the biological diversity on Hainan Island,China

Purpose  

The performance of nature reserves depends on the degree to which they represent a region's full biodiversity. Here, we conducted a study on Hainan Island, China, to assess how well Hainan's biodiversity features were captured by existing nature reserves. We also explored the driving forces behind the current protection pattern so as to provide guidelines for improving the island's conservation system.     

新型复合混凝吸附药剂对无铅皮蛋废水的处理

皮蛋废水水质相当复杂,既属于含重金属离子废水,又属于中等浓度含盐有机废水.针对皮蛋废水特点,采用混凝+吸附方法预处理皮蛋废水,将PAC与粉煤灰按2:5的投加比混合复制成一种新型复合混凝吸附剂,通过正交实验考察了复合药剂的较佳处理条件.结果表明,在投加量为5 g/L,pH为6.5左右,搅拌时间约为14 min,处理温度为...     

一株芴降解菌的分离鉴定及其对多环芳烃的降解广谱性研究

从某焦化厂活性污泥中筛选出一株芴的优势降解菌株W-1,经形态学观察、生理生化实验和16S rDNA基因序列分析,确定W-1为粪产碱杆菌.在接种量10%(V/V),初始芴浓度40 mg/L,pH 7.0,温度30℃的条件下,接种培养11 d后,菌株W-1对芴的降解效率达到87.8%.菌株W-1对多环芳烃的降解具有广谱性,...     

Fenton和类Fenton氧化处理地下水中BTEX及其动力学

研究比较Fenton试剂和类Fenton试剂氧化处理地下水中苯、甲苯、乙苯和二甲苯(BTEX)的效果及动力学.结果表明,Fenton氧化处理BTEX较类Fenton效果好,且反应过程中体系均处于强氧化环境,pH值维持在3左右;Fenton和类Fenton氧化去除BTEX过程均符合二级反应动力学方程:1/C=kt+1/C...     

脱硫后净烟气携带浆液量监测的实验研究

在WFGD系统中,净烟气携带的浆液液滴引起后续设备的腐蚀堵塞,带来的景观污染问题影响周围居民的正常生活.为了精确量化脱硫后净烟气携带浆液量,提出了适用于环境监测专业的测试取样分析方法,并对该方法进行了讨论分析.实验结果表明:该方法的适用范围为净烟气浆液液滴含量在1.1 mg/Nm3以上,通过对取样分析关键环节的讨论分析...     

化学混凝-两级BAF工艺处理低温城市污水中试研究

以大庆东城污水处理厂进水为实验原水,采用化学混凝-两级曝气生物滤池(BAF)组合工艺进行现场中试研究(12 m3/d),重点考察了在化学混凝的强化作用下,曝气生物滤池工艺对低温城市污水中有机物、氮和磷等污染物的净化效能。实验结果表明,单独采用两级曝气生物滤池工艺,当原水COD、NH3-N、TN和TP的平均浓度分别为45...     

铁炭-混凝沉淀-生化处理强酸性染料废水的中试研究

采用铁炭-混凝沉淀-水解酸化-生物接触氧化工艺对强酸性染料废水进行中试处理研究。在铁炭微电解单元主要考察了铁炭比、HRT和曝气量大小对处理效果的影响;在水解酸化单元主要考察了进水pH和HRT对处理效果的影响。通过铁炭微电解和水解酸化,在大幅改善废水的可生化性的同时,还可以有效去除废水的色度、削减有机负荷,以保证后续的生物接触氧化工艺的高效稳定运行。在生物接触氧化单元主要考察了进水浓度、HRT对处理效果的影响。经过组合工艺的处理,最终的出水COD〈75 mg/L,出水色度〈40倍。     

甲基红在壳聚糖上吸附富集的研究

研究了pH、初始浓度、时间及温度对甲基红在壳聚糖上吸附富集的影响。结果表明,pH是影响甲基红吸附富集的重要因素,最佳pH3．4。其动力学行为更好地符合Lagergren准二级反应动力学模型,随着温度增加,平衡吸附量减少。吸附过程的表观活化能（Ea）为7．518kJ／mol。壳聚糖对甲基红的吸附过程较好地符合Freundlich吸附等温方程。计算得到吸附过程的热力学参数△G0、△H0。和△S0分别为-24．88kJ／mol（303K）、-22．15kJ／mol和8．783J／（mol·K）,表明壳聚糖对甲基红的吸附是一个自发的放热过程。红外光谱分析得到,壳聚糖吸附甲基红的过程中,壳聚糖分子中存在的大量羟基和氨基发挥了主要作用。