一株产电菌嗜根考克氏菌(Kocuria rhizophila)的分离及其产电性能优化

本研究以天津泰达污水处理厂污泥浓缩间的污泥为接种物,启动并运行了微生物燃料电池(MFCs).从富集的阳极生物膜上分离得到了一株纯培养的微生物菌种,命名为P2-A-5.研究发现,菌株P2-A-5的16S rDNA序列与菌株Kocuria rhizophila DC2201具有100%的同源性,结合该菌的形态特征和生理生化实验,将其归属为嗜根考克氏菌(Kocuria rhizophila).通过化学剂处理、底物种类和浓度的优化,进一步提高其在微生物燃料电池中的产电性能.结果表明,菌株K.rhizophila P2-A-5经0.5 mg·L-1溶菌酶处理45 min后,接种到以2.0 g·L-1海藻糖为底物的阳极液中运行MFCs,其功率密度达到314.8 m W·m-2,比优化前(74.9 m W·m-2)提高了320.3%.这是首次对K.rhizophila种内微生物产电性能及其在微生物燃料电池中应用的报道,其成果对于丰富产电微生物的多样性,挖掘更多具有高电化学活性的微生物菌种,提高其产电性能具有重要的理论意义.     

Adsorption and biodegradation of three selected endocrine disrupting chemicals in river-based artificial groundwater recharge with reclaimed municipal wastewater

Endocrine disrupting chemical(EDC) pollution in river-based artificial groundwater recharge using reclaimed municipal wastewater poses a potential threat to groundwater-based drinking water supplies in Beijing, China. Lab-scale leaching column experiments simulating recharge were conducted to study the adsorption, biodegradation, and transport characteristics of three selected EDCs: 17β-estradiol(E2), 17α-ethinylestradiol(EE2) and bisphenol A(BPA). The three recharge columns were operated under the conditions of continual sterilization recharge(CSR), continual recharge(CR), and wetting and drying alternative recharge(WDAR). The results showed that the attenuation effect of the EDCs was in the order of WDAR CR CSR system and E2 EE2 BPA, which followed first-order kinetics. The EDC attenuation rate constants were 0.0783, 0.0505, and 0.0479 m-1 for E2, EE2 and BPA in the CR system, respectively. The removal rates of E2, EE2, and BPA in the CR system were 98%, 96% and 92%, which mainly depended on biodegradation and were affected by water temperature.In the CR system, the concentrations of BPA, EE2, and E2 in soil were 4, 6 and 10 times higher than in the WDAR system, respectively. According to the DGGE fingerprints, the bacterial community in the bottom layer was more diverse than in the upper layer, which was related to the EDC concentrations in the water-soil system. The dominant group was found to be proteobacteria, including Betaproteobacteria and Alphaproteobacteria, suggesting that these microbes might play an important role in EDC degradation.     

Formation and speciation of disinfection byproducts during chlor(am)ination of aquarium seawater

The chemistry associated with the disinfection of aquarium seawater is more complicated than that of freshwater, therefore limited information is available on the formation and speciation of disinfection byproducts(DBPs) in marine aquaria. In this study, the effects of organic precursors, bromide(Br-) and pre-ozonation on the formation and speciation of several typical classes of DBPs, including trihalomethanes(THM4), haloacetic acids(HAAs),iodinated trihalomethanes(I-THMs), and haloacetamides(HAc Ams), were investigated during the chlorination/chloramination of aquarium seawater. Results indicate that with an increase in dissolved organic carbon concentration from 4.5 to 9.4 mg/L, the concentrations of THM4 and HAAs increased by 3.2–7.8 times under chlorination and by 1.1–2.3 times under chloramination. An increase in Br-concentration from 3 to 68 mg/L generally enhanced the formation of THM4, I-THMs and HAc Ams and increased the bromine substitution factors of all studied DBPs as well, whereas it impacted insignificantly on the yield of HAAs. Pre-ozonation with 1 mg/L O3 dose substantially reduced the formation of all studied DBPs in the subsequent chlorination and I-THMs in the subsequent chloramination. Because chloramination produces much lower amounts of DBPs than chlorination, it tends to be more suitable for disinfection of aquarium seawater.     

Investigation of physico-chemical properties and microbial community during poultry manure co-composting process

Co-composting of poultry manure and rubber wood sawdust was performed with the ratio of 2:1(V/V) for a period of 60 days. An investigation was carried out to study the extracellular enzymatic activities and structural degradation utilizing Fourier transform infrared spectroscopy(FT-IR), thermogravimetry and differential thermal analysis(TG/DTA)and scanning electron microscopy(SEM). The microbial succession was also determined by using denaturing gel gradient electrophoresis(DGGE). The compost was able to reach its highest temperature of 71°C at day 3 and stabilized between 30 and 40°C for 8 weeks.CMCase, FPase and β-glucosidase acted synergistically in order to degrade the cellulosic substrate. The xylanase activities increased gradually during the composting and reached the peak value of 11.637 U/g on day 35, followed by a sharp decline. Both Li P and Mn P activities reached their peak values on day 35 with 0.431 and 0.132 U/g respectively. The FT-IR spectra revealed an increase in aromaticity and a decrease in aliphatic compounds such as carbohydrates as decomposition proceeded. TGA/DTG data exhibited significant changes in weight loss in compost samples, indicating degradation of organic matter. SEM micrographs showed higher amounts of parenchyma exposed on the surface of rubber wood sawdust at day 60, showing significant degradation. DGGE and 16 S r DNA analyses showed that Burkholderia sp., Pandoraea sp., and Pseudomonas sp. were present throughout the composting process. Ornithinibacillus sp. and Castellaniella ginsengisoli were only found in the initial stage of the composting, while different strains of Burkholderia sp. also occurred in the later stage of composting.     

New insights into disruption of iron homeostasis by environmental pollutants

Among the numerous health conditions environmental pollutants can cause, chronic exposure to pollutants including persistent organic pollutants (POPs) and heavy metals has been shown to disturb a specific biological homeostatic process, the iron metabolism in human body. Disorders of iron metabolism are among the common diseases of humans and encompass a broad spectrum of diseases with different clinical manifestations, ranging from anemia to iron overload, and possibly to neurodegenerative diseases and cancer. Hepcidin–ferroportin (FPN) signaling is one of the key mechanisms responsible for iron supply, utilization, recycling, and storage, and recent studies demonstrated that exposure to environmental pollutants including POPs and heavy metals could lead to disruption of the hepcidin–FPN axis along with disordered systemic iron homeostasis and diseases. This article introduces and highlights the accompanying review article by Drs. Xu and Liu in this journal, which elaborates in detail the adverse effects of environmental pollutants on iron metabolism, and the mechanisms responsible for these toxicological outcomes. It also points out the knowledge gaps still existing in this subject matter. Research that will fill these gaps will improve our understanding of the issue and provide useful information to prevent or treat diseases induced by environmental pollutants.     

Heterogeneous oxidation of SO2 by O3-aged black carbon and its dithiothreitol oxidative potential

Ozone (O₃) is an important atmospheric oxidant. Black carbon (BC) particles released into the atmosphere undergo an aging process via O₃ oxidation. O₃-aged BC particles may change their uptake ability toward trace reducing gases such as SO₂ in the atmosphere, leading to different environmental and health effects. In this paper, the heterogeneous reaction process between O₃-aged BC and SO₂ was explored via in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Combined with ion chromatography (IC), DRIFTS was used to qualitatively and quantitatively analyze the sulfate product. The results showed that O₃-aged BC had stronger SO₂ oxidation ability than fresh BC, and the reactive species/sites generated on the surface had an important role in the oxidation of SO₂. Relative humidity or 254 nm UV (ultraviolet) light illumination enhanced the oxidation uptake of SO₂ on O₃-aged BC. The oxidation potentials of the BC particles were detected via dithiothreitol (DTT) assay. The DTT activity over BC was decreased in the process of SO₂ reduction, with the consumption of oxidative active sites.     

Research on whole life cycle carbon emission model of typical buildings

Based on the theory of life cycle assessment (LCA), this article analyzes the influence factors on carbon emissions from residential buildings. In the article, the life cycle of residential buildings has been divided into five stages: building materials production period, construction period, operation and maintenance period, demolition period, and solid waste recycle and disposal period. Based on this definition, the authors provide a theoretical model to calculate carbon emissions of residential building life cycle. In particular, the factor of human activities was introduced in the calculation of carbon emissions from the buildings. Furthermore, the authors put forward a model for calculation with the unit of carbon emissions for per-capita living space.     

Leaching-induced migration and compositional form change of Cu,Zn, and Cd from sludge to loess

Land utilization of sewage sludge has become one of the major issues in environmental mitigation in China. This is particularly important in the Loess Plateau of Northwest China. Sludge enriched with organic matter and nutrients might effectively help to resolve the problems of silty loess soils as evidenced by porosity defect, structural alterations and absence of fertility. After sludge flows into the loess, irrigation water contains heavy metals that leach and migrate into sludge and consequently related human health risks may occur that raise concerns; and this situation needs to be rectified. The characteristics of the vertical migration and composition form change of Cu, Zn, and Cd from composted sludge to loess, and corresponding influencing factors, were investigated by performing a soil column simulation test under the leaching treatment of a one-year irrigation water capacity. Results demonstrated that: (1) composted sludge significantly improved loess fertility, and irrigation leaching transported only a small quantity of organic matter in sludge in the plough layer; (2) although some of the Cu, Zn, and Cd in composted sludge migrated to and concentrated in the middle and upper layers of the soil column during leaching, these metals were mostly retained in the plough layer; and (3) after the leaching treatment of the one-year irrigation water capacity, the compositions of Cu, Zn, and Cd (particularly Cu and Zn) in both plough layer and loess began to stabilize with low concentrations in the exudate. These findings confirmed the applicability of composted sludge in loess regions. This study provided a new insight into the sludge reuse in alkaline soils in arid and semi-arid region.     

北京10个常绿树种颗粒物吸附能力研究

大气中颗粒物PM(particulate matter)不仅造成环境污染,还对人体造成严重的危害.城市绿色植物作为大气过滤器,能够有效地提高城市空气质量,保护人体健康.因此了解不同树种对空气颗粒物的吸附滞纳作用是必要的.以北京植物园10种常绿植被为研究对象,应用空气气溶胶再发生器(QRJZFSQ-I)测定了北京市常见6种乔木和4种灌木叶片对空气总悬浮颗粒物(TSP)、PM10、PM2.5和PM1.0的吸附能力.结果表明:1不同树种叶片表面附着颗粒物的能力差异明显,最高的是雪松(Cedrus deodara)和油松(Pinus tabuliformis),吸附量分别是(18.95±0.71)μg·cm-2和(14.61±0.78)μg·cm-2,冷杉(Abies fabri)最小,为(8.02±0.4)μg·cm-2;2不同树种叶片单位面积对不同颗粒物的附着能力也存在差异,附着PM10能力最强的是油松和雪松,附着PM2.5能力最强的是雪松、铺地柏(Juniperus procumbens)、龙柏(Juniperus chinensis cv.kaizuka)和油松,附着PM1.0能力最强的是雪松、铺地柏、冷杉和油松;3不同月份叶片上附着的各粒级颗粒物(PM10、PM2.5)占TSP的比例不同.其中PM10在4~6月之间主要表现两种变化趋势,一是先上升后下降,主要为灌木树种;二是逐渐上升,主要的树种是乔木树种.而PM2.5则没有这种明显的变化趋势.