Distribution and bioavailability of ceria nanoparticles in an aquatic ecosystem model

Along with the increasing utilization of engineered nanoparticles, there is a growing concern for the potential environmental and health effects of exposure to these newly designed materials. Understanding the behavior of nanoparticles in the environment is a basic need. The present study aims to investigate the distribution and fate of ceria nanoparticles in an aquatic system model which consists of sediments, water, hornworts, fish and snails, using a radiotracer technique. Concentrations of ceria in the samples at regular time intervals were measured. Ceria nanoparticles were readily removed from the water column and partitioned between different organisms. Both snail and fish have fast absorption and clearance abilities. Hornwort has the highest bioaccumulation factors. At the end of the experiment, sediments accumulated most of the nanoparticles with a recovery of 75.7 ± 27.3% of total ceria nanoparticles, suggesting that sediments are major sinks of ceria nanoparticles.     

Formation pathways of polychlorinated dibenzofurans (PCDFs) in sediments contaminated with PCBs during the thermal desorption process

Thermal desorption has attracted considerable interest as a remediation technology for the removal of dioxins and polychlorinated biphenyls (PCBs) from contaminated soils and sediments. Although several research groups have confirmed that polychlorinated dibenzofurans (PCDFs) are formed from PCBs during the thermal desorption of sediments contaminated with PCB, the formation pathways remain poorly understood. Herein, thermal desorption has been used to develop a greater understanding of the formation pathways of PCDFs from sediments contaminated with PCBs. PCB decomposition experiments of sediments contaminated with PCBs were performed over 5 min at 450 °C with a gas composition of 10% O(2)/90% N(2), either in the absence (Run 1) or presence (Run 2-4) of one of three different (13)C(12)-labeled PCB individual standards. The results of Run 1 showed that 99.96% of PCBs and 98.40% of polychlorinated dibenzo-p-dioxins (PCDDs) in the treated sediments had decomposed, whereas the concentration levels of PCDFs had increased by a factor of 31. The addition of different (13)C(12)-labeled PCBs to the sediment sample yielded different (13)C(12)-PCDFs isomer patterns, with formation pathways including loss of ortho-Cl(2), loss of HCl involving a 2,3-chlorine shift, loss of ortho-H(2) and dechlorination.     

Biological degradation and microbial function effect of norfloxacin in a soil under different conditions

This paper investigated the degradation kinetics of norfloxacin in a soil, and its effects on soil respiration and nitrogen transformation under different conditions. Compared to the sterile control, the degradation rates of norfloxacin in the non-sterile soil were greatly enhanced, suggesting that microorganisms played a major role in the degradation. Accelerated degradation for norfloxacin in the soil was observed with decreasing concentrations (30 mg/kg to 5 mg/kg) with its half-life decreasing from 62 days to 31 days. Amending swine manure into the soil and increasing the soil moisture level enhanced the biological degradation of norfloxacin. No obvious inhibition of norfloxacin on soil respiration was observed in the soil, while only slight effect on nitrogen transformation was found. The results suggested that norfloxacin at the reported environmental concentrations (<100 mg/kg) would have little effect on microbial activity and functions in the soils.     

Removal of genotoxicity in chlorinated secondary effluent of a domestic wastewater treatment plant during dechlorination

Purpose  

Dechlorination with tetravalent sulfur is widely used in wastewater treatment processes after chlorination. Dechlorination can remove certain genotoxic disinfection by-products (DBPs). However, the reactions occurring during dechlorination of chlorinated secondary effluent and their genotoxic chemicals are still very complex, and the related genotoxicity changes remain unknown. Therefore, the effects of dechlorination on genotoxicity in secondary effluent and its fractions and typical genotoxic chemical after chlorination were evaluated.     

Phytoremediation of the polluted Waigang River and general survey on variation of phytoplankton population

The Waigang River, a major tributary of the Qinhuai River system, has suffered from long-standing pollution because of lack of management. Restoration was commenced in April 2006 to reduce pollutants and improve water quality. Four ecological areas and ten surface carriers were constructed for the culture of plants (mainly water hyacinth (Eichhornia crassipes) and ryegrass (Lolium perenne L.)) for phytoremediation. Chemical oxygen demand (COD), total suspended solids (TSS), total phosphorus, total nitrogen (TN), ammonia?Cnitrogen (NH₃?CN), water transparency, and variations in phytoplankton population were investigated to evaluate the effects of restoration. Over 36?months, TSS, COD, TN, and NH₃?CN levels decreased by 91.1, 55.3, 91.5, and 86.5?%, respectively. Transparency increased from 25?cm in 2006 to 165?cm in 2009. Improvements in water quality significantly enhanced the diversity of phytoplankton, which were harmed by pollution stress. Our results show that the water hyacinth and ryegrass cultured in the ecological areas and the surface carriers can be used to restore other heavily polluted rivers with conditions similar to those of the Waigang River, especially in the initial stages of restoration.     

石油类污染物自然衰减能力现场试验验证研究

在北京地区某加油站开展的前期石油类污染物自然衰减现场试验的基础上,进一步开展了验证试验,结果表明本次试验得到的挥发性有机物(VOCs)变化趋势及O2、CO2含量沿土壤深度分布和前期试验结果呈现相同的规律,说明基于自然衰减法设计实施的加油站现场试验检测分析结果可靠,试验方法具有合理性、可操作性及可重复性.进一步的理论分析对前期试验结果进行了验证,得出以下结论:(1)通过氧平衡和碳平衡计算对加油站土壤内的自然衰减方式进行评价,验证了该加油站地下土壤中实际发生的微生物降解既有需氧降解也有厌氧降解;(2)利用有机物的一级衰减模型对该污染现场土壤中石油类污染物的降解速率和半衰期进行计算表明,2次试验计算得到的石油类污染物的半衰期基本一致,该污染现场石油类污染物的半衰期为50 d左右;(3)在此基础上,对该加油站包气带土壤的自然衰减能力和环境质量进行评价,2次试验结果均表明该污染现场在自然衰减的作用下已经不存在环境风险.     

Characterization of carbonic anhydrase II from Chlorella vulgaris in bio-CO2 capture

Carbonic anhydrase II (CA II) can catalyze the reversible hydration reaction of CO₂ at a maximum of 1.4?×?10⁶ molecules of CO₂ per second. The crude intracellular enzyme extract containing CA II was derived from Chlorella vulgaris. A successful CO₂ capture experiment with the presence of calcium had been conducted on the premise that the temperature was conditioned at a scope of 30?C40?°C, that the biocatalyst-nurtured algal growth period lasted 3?days, and that pH ranged from7.5 to 8.5. Ions of K⁺, Na⁺, Ca²⁺, Co²⁺, Cu²⁺, Fe³⁺, Mg²⁺, Mn²⁺, and Zn²⁺ at 0.01, 0.1, and 0.5?M were found to exhibit no more than 30?% inhibition on the residual activity of the biocatalyst. It is reasonable to expect that calcification catalyzed by microalgae presents an alternative to geological carbon capture and sequestration through a chain of fundamental researches carried on under the guidance of sequestration technology.     

芘高效降解菌ZQ_5的培养条件及无机元素对其降解效率的影响

以从我国最大的石油污水灌区之一——沈抚灌区污染土壤分离到的以芘为惟一碳源、能源生长的高效降解菌株ZQ5为实验材料,通过对菌株ZQ5培养条件的优化,以及采用摇瓶振荡培养方法测定菌株ZQ5对不同浓度芘的降解率,表明：菌株ZQ5在30℃振荡培养16 d后对150 mg/L芘的降解率为90.31%。通过模拟稻田施用N、P和K肥等的土壤环境,探索了无机营养元素对降解菌ZQ5降解能力的影响,发现土壤中混合加入N、P和K无机营养元素的降解率能达到82%以上,比单加某种营养元素对降解菌ZQ5的降解效果好。本研究结果可以指导稻田PAHs的原位生物修复。     

不同粒径零价铁（ZVI）对污水污泥H_2S和CH_4释放速率的影响

考察了不同粒径零价铁（ZVI）,包括200目普通铁粉（200m-ZVI）、800目超细铁粉（800m-ZVI）和纳米铁粉（nZVI,粒径=20 nm）,对污水污泥的硫化氢和甲烷释放速率的影响。研究发现：（1）在22 d内,添加0.1%的200m-ZVI使污泥的硫化氢释放速率提高48.0%,而添加0.1%的800-ZVI和nZVI,则使污泥的硫化氢释放速率分别降低33.1%和77.1%;（2）不同粒径ZVI均可以提高污泥沼气中的甲烷浓度,且依次为nZVI〉800m-ZVI〉200m-ZVI;（3）在23 d内,添加0.1%的200m-ZVI和nZVI使污泥的甲烷累计产生量分别提高了15.5%和40.6%,而添加0.1%800m-ZVI则使甲烷产生量降低了12.5%。nZVI可以有效控制污泥的硫化氢释放,并显著提升污泥在厌氧发酵过程的产甲烷速率。     

k-C*模型的人工湿地模拟研究

采用自由表面流人工湿地,对广东省中山市某小区对应段的河涌进行生态修复改造。基于k-C*模型的计算结果表明,在对现有河涌的面积的利用下,TP和NH4+-N的去除效果受到限制。采用多因素正交实验对模型的计算结果进行实验验证和分析,研究了4种植物、4种基质,分别在2、4、6和8 d水力停留时间(HRT)下对TP和NH4+-N的去除效果,得到影响TP和NH4+-N去除效果的因素主次顺序分别为基质→植物→HRT和基质→HRT→植物;各因素的最佳水平条件分别为:风车草、颗粒活性炭、4 d(HRT)。在最佳水平条件下进行实验,结果表明,TP和NH4+-N的浓度均可达到出水排放标准浓度指标。k-C*模型的计算值总是比实验值偏高,但两者之间的误差在一个数量级范围内。