Effects of silver nanoparticles with different dosing regimens and exposure media on artificial ecosystem

Due to the wide use of silver nanoparticles (AgNPs) in various fields, it is crucial to explore the potential negative impacts on the aquatic environment of AgNPs entering into the environment in different ways. In this study, comparative experiments were conducted to investigate the toxicological impacts of polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs) with two kinds of dosing regimens, continuous and one-time pulsed dosing, in different exposure media (deionized water and XiangJiang River water). There were a number of quite different experimental results (including 100% mortality of zebrafish, decline in the activity of enzymes, and lowest number and length of adventitious roots) in the one-time pulsed dosing regimen at high PVP-AgNP concentration exposure (HOE) compared to the three other treatments. Meanwhile, we determined that the concentration of leached silver ions from PVP-AgNPs was too low to play a role in zebrafish death. Those results showed that HOE led to a range of dramatic ecosystem impacts which were more destructive than those of other treatments. Moreover, compared with the continuous dosing regimen, despite the fact that higher toxicity was observed for HOE, there was little difference in the removal of total silver from the aquatic environment for the different dosing regimens. No obvious differences in ecological impacts were observed between different water columns under low concentration exposure. Overall, this work highlighted the fact that the toxicity of AgNPs was impacted by different dosing regimens in different exposure media, which may be helpful for assessments of ecological impacts on aquatic environments.     

遵义市PM10和PM2.5污染水平时间分布及其与气象条件的关系研究

对遵义市2014年1月1日-12月31日大气颗粒物在线监测数据分析结果表明,全年PM10和PM2.5质量浓度的变化幅度较大,但变化趋势相似,且具有较好的相关性,其中冬季>春季>秋季>夏季;日变化呈双峰特征分布,夜间峰值比中午峰值大,且夜间PM2.5浓度呈区域性变化特征.选取日平均气温、相对湿度及风速等气象因子,利用Spearman秩相关分析表明遵义市全年PM10和PM2.5质量浓度与气温、相对湿度及风速等气象条件均呈负相关.     

载磷Mg/Al/Fe-LDO的微波辅助溶剂解吸方法特性

针对载磷Mg/Al/Fe-LDO再生利用与解吸液富集回收磷的问题,通过对比直接溶剂解吸法与微波辅助溶剂解吸法在解吸条件、吸附性能与材料层状结构恢复方面的差异,考察了微波辅助溶剂解吸方法的技术特性,并分析了其解吸机制.结果显示,与直接溶剂解吸法相比,微波辅助溶剂解吸法解吸时间由4 h缩短为10～30 min,解吸效果提高15%以上;在同等解吸效果前提下,组合解吸剂(Na_2CO_3+NaOH)浓度降低2倍;解吸剂用量减少10倍.载磷Mg/Al/Fe-LDO经微波辅助溶剂解吸-焙烧再生后,吸附性能得到较好地恢复,3次吸附-解吸-焙烧后再生率接近90%,比直接溶剂解吸-焙烧再生提高40%.由于微波能够强化溶剂离子热运动、促进离子传质与扩散过程,加快离子交换速率,有利于材料层状结构的有效恢复,因此,微波辅助溶剂解吸法能够在较低解吸剂浓度与用量条件下,实现对载磷Mg/Al/Fe-LDO的高效、快速解吸,有利于污水中磷的富集回收.     

黔中岩溶地区草地土壤CO2的稳定碳同位素组成

黔中岩溶地区草地土壤 CO₂ 的δ¹³C值在地 -气界面层上随土层深度的增加而降低 ,在地 -气界面层以下 ,土壤 CO₂ 的δ¹³C值基本不变 .土壤 CO₂ 的 δ¹³C值存在季节变化与昼夜变化的特征 .夏季 CO₂ 的 δ¹³C值最高 (-15.5‰ ) ,冬季 CO₂ 的 δ¹³C值最低 (-18.9‰) ;从夏季到冬季 ,土壤 CO₂ 的 δ¹³C稳定值逐渐降低 ,降低幅度超过 3‰ .在一天中 ,中午土壤 CO₂ 的 δ¹³C值最高(-14.0‰ ) ,早晚土壤 CO₂ 的δ¹³C值较低 (-15.4‰ )     

Linear alkylbenzenes in riverine runoff of the Pearl River Delta (China) and their application as anthropogenic molecular markers in coastal environments

The average concentrations of ∑LABs (sum of C₁₀-C₁₃-LABs) in runoff samples collected from the eight major riverine outlets of the Pearl River Delta (PRD) of China ranged from 1.4 to 6124 ng/L in the dissolved phase and from 0.01 to 11.4 μg/g dry weight in the particulate phase during March 2005-February 2006. The annual riverine flux of ∑LABs from the PRD to the coastal ocean was estimated at approximately 14 tons/yr. The inventories of ∑LABs in agricultural lands of Guangdong Province ranged from 313 to 1825 kg/yr. The early and late rice fields were the major sink of LABs, accounting for approximately 68% of total LABs inventory in agricultural lands. The social-economically estimated annual discharge of LABs from household detergents in the PRD was ∼696 tons/yr, more than an order of magnitude higher than that estimated from field measurements (about 14 tons/yr), which was attributed to several factors.     

大豆蛋白和屠宰废水处理工艺研究

介绍了两公司大豆蛋白废水的水质水量和性质特征，分析工程的工艺设计和调试运行状况。对大豆蛋白和屠宰废水的处理，采用混和处理的总体工艺，理论研究和运行实践表明，混和处理利于均衡生物处理营养，优化厌氧处理工艺型式及参数。污泥培养时，尽快从间歇运行变为连续运行，利于基质和污泥的混和接触，促进油脂和脂肪酸的降解，防止油和脂肪酸的积累及其抑制作用，防止油脂包覆污泥，造成污泥漂浮流失。     

生物脱氮除磷活性污泥系统复合模拟方法

为避免繁琐的参数校核工作,提出了活性污泥2 d号模型(ASM2d)和人工神经网络(ANNs)相结合的复合模拟方法。考察了复合方法在某污水处理厂生物脱氮除磷工艺中的应用情况。研究表明,ANNs能够准确地模拟出水实测值与未经校核的ASM2d机理模型的估计值之间的差值。利用Levenberg-Marquardt算法,对出水氨氮、总氮和总磷分别建立网络结构为5-12-1、5-8-1和5-8-1的ANNs子模型,将这些子模型输出同ASM2d机理模型输出相加便得到复合模型输出。复合模型估计值对前10.4 d(ANNs子模型训练数据时段)出水氨氮、总氮和总磷浓度的拟合平均绝对百分比误差分别为0.267、0.055和0.048;其对后2.6 d(ANNs子模型测试数据时段)出水氨氮、总氮和总磷浓度的预测平均绝对百分比误差分别为0.332、0.083和0.069。均方根误差、平均绝对误差等评价指标也表明复合模型能够给出合理的模拟结果。     

Ca2+在净水生物膜团聚体培养中的影响研究

通过在5组相同型号的SBBR反应器(A、B、C、D和E)内调节进水中的Ca2+含量,研究Ca2+在净水生物膜团聚体培养过程的作用影响.结果表明,进水Ca2+投加浓度为25 mg/L时驯化培养的生物膜团聚体具有较好的抗挤压能力,抗压强度达到了22 N/cm2,密度为1.059 g/cm3,活性微生物的百分含量达到了86.90%,远远高于一般污泥团聚体中的微生物含量.分析运行效果,反应器C和D的生物膜团聚体通过29 d的驯化培养就达到了一个比较好的净水效果,并能维持稳定状态,相比于一般生物膜反应器的驯化时间有所缩短.不同进水负荷条件下氮氮的去除率变化表明,反应器C和D针对不同进水负荷表现出来的适应效果明显优于其他反应器.     

SCX型脱硫除尘器内部气固两相流场数值模拟

采用FLUENT软件对SCX型脱硫除尘器内部气固两相流场进行数值模拟.气相采用Realizable k-ε湍流模型,颗粒相采用离散相模型(DPM),压力-速度耦合算法选择SIMPLE进行计算.分析了装置内z=0截面上气相压力和速度的分布,并对不同粒径颗粒的浓度和运动轨迹进行计算,还在考虑重力及不考虑重力2种情况下分析了...     

稻草的水热碳化研究

利用水热碳化技术,在1 000 mL的反应釜中,考察了反应温度和停留时间对于稻草水热碳化的影响。结果表明,稻草碳化得到的气相产物主要为CO2、液相产物主要为乙酸和葡萄糖。随着反应温度和停留时间的提高,CO2、乙酸的产率以及生物炭(固相产物)的能量密度呈上升趋势,而生物炭的产率则呈现相反的趋势。在低温条件下(200℃左右),可获得较高葡萄糖产率。生物炭的吸水性实验表明,在反应温度为260℃,停留时间为1 h的条件下,生物炭的产率达到稳定。扫描电镜分析结果说明,经过碳化后的稻草整体呈现碎片状态,并伴有大量蜂窝状结构。