有机改性膨润土在印染废水处理中的应用

膨润土是一种非常有用的非金属矿物原料,其有机改性得到的有机改性膨润土可以较好地去除印染废水中的有机污染物和色度。本文综述了有机改性膨润土的制备方法及其在印染废水处理中的应用现状。     

Evaluation of accuracy of linear regression models in predicting urban stormwater discharge characteristics

Stormwater runoff has been identified as a source of pollution for the environment, especially for receiving waters. In order to quantify and manage the impacts of stormwater runoff on the environment, predictive models and mathematical models have been developed. Predictive tools such as regression models have been widely used to predict stormwater discharge characteristics. Storm event characteristics, such as antecedent dry days （ADD）, have been related to response variables, such as pollutant loads and concentrations. However it has been a controversial issue among many studies to consider ADD as an important variable in predicting stormwater discharge characteristics. In this study, we examined the accuracy of general linear regression models in predicting discharge characteristics of roadway runoff. A total of 17 storm events were monitored in two highway segments, located in Gwangju, Korea. Data from the monitoring were used to calibrate United States Environmental Protection Agency＇s Storm Water Management Model （SWMM）. The calibrated SWMM was simulated for 55 storm events, and the results of total suspended solid （TSS） discharge loads and event mean concentrations （EMC） were extracted. From these data, linear regression models were developed. R2 and p-values of the regression of ADD for both TSS loads and EMCs were investigated. Results showed that pollutant loads were better predicted than pollutant EMC in the multiple regression models. Regression may not provide the true effect of site-specific characteristics, due to uncertainty in the data.     

Photocatalytic activity of Fe-doped CaTiO3 under UV-visible light

The photocatalytic degradation of methylene blue（MB） over Fe-doped CaTiO3 under UV-visible light was investigated. The as-prepared samples were characterized using X-ray diffraction（XRD）, scanning electron microscope（SEM） equipped with an energy dispersive spectrometer（EDS） system, Fourier transform infrared spectra（FT-IR）, and UV-visible diffuse reflectance spectroscopy（DRS）. The results show that the doping with Fe significantly promoted the light absorption ability of CaTiO3 in the visible light region. The Fe-doped CaTiO3 exhibited higher photocatalytic activity than CaTiO3 for the degradation of MB.However, the photocatalytic activity of the Fe-doped CaTiO3 was greatly influenced by the calcination temperature during the preparation process. The Fe-doped CaTiO3 prepared at500°C exhibited the best photocatalytic activity, with degradation of almost 100% MB（10 ppm）under UV-visible light for 180 min.     

Origin of major ions in monthly rainfall events at the Bamenda Highlands, North West Cameroon

Rainwater characteristics can reveal emissions from various anthropogenic and natural sources into the atmosphere. The physico-chemical characteristics of 44 monthly rainfall events （collected between January and December 2012） from 4 weather stations （Bamenda, Ndop plain, Ndawara and Kumbo） in the Bamenda Highlands （BH） were investigated. The purpose was to determine the sources of chemical species, their seasonal inputs and suitability of the rainwater for drinking. The mean pH of 5 indicated the slightly acidic nature of the rainwater. Average total dissolved solids （TDS） were low （6.7 mg/L）, characteristic of unpolluted atmospheric moisture/air. Major ion concentrations （mg/L） were low and in the order K＋ 〉 Ca2＋ 〉 Mg2~ 〉 Na＋ for cations and NO3 〉〉 HCO3 〉 SO] 〉 CI- 〉 PO3- 〉 F- for anions. The average rainwater in the area was mixed Ca-Mg-SO4-CI water type. The CI-/Na＋ ratio （1.04） was comparable to that of seawater （1.16）, an indication that N a＋ and CI originated mainly from marine （Atlantic Ocean） aerosols. High enrichments of Ca2＋, Mg2＋ and SO2- to Na＋ ratios relative to seawater ratios （constituting 44% of the total ions） demonstrated their terrigenous origin, mainly from Saharan and Sahelian arid dusts. The K＋/Na＋ ratio （2.24）, which was similar to tropical vegetation ash （2.38）, and NO3 was essentially from biomass burning. Light （〈 100 mm） pre-monsoon and post-monsoon convective rains were enriched in major ions than the heavy （〉 100 mm） monsoon rains, indicating a high contribution of major ions during the low convective showers. Despite the acidic nature, the TDS and major ion concentrations classified the rainwater as potable based on the WHO guidelines.     

Evaluation of soil washing process with carboxymethyl-β-cyclodextrin and carboxymethyl chitosan for recovery of PAHs/heavy metals/fluorine from metallurgic plant site

Polycyclic aromatic hydrocarbons(PAHs)/heavy metals/fluorine(F) mixed-contaminated sites caused by abandoned metallurgic plants are receiving wide attention. To address the associated environmental problems,this study was initiated to investigate the feasibility of using carboxymethyl-β-cyclodextrin(CMCD) and carboxymethyl chitosan(CMC) solution to enhance ex situ soil washing for extracting mixed contaminants. Further,Tenax extraction method was combined with a first-three-compartment model to evaluate the environmental risk of residual PAHs in washed soil. In addition,the redistribution of heavy metals/F after decontamination was also estimated using a sequential extraction procedure. Three successive washing cycles using50 g/L CMCD and 5 g/L CMC solution were effective to remove 94.3% of total PAHs,93.2% of Pb,85.8% of Cd,93.4% of Cr,83.2% of Ni and 97.3% of F simultaneously. After the 3rd washing,the residual PAHs mainly existed as very slowly desorbing fractions,which were in the form of well-aged,well-sequestered compounds; while the remaining Pb,Cd,Cr,Ni and F mainly existed as Fe–Mn oxide and residual fractions,which were always present in stable mineral forms or bound to non-labile soil fractions. Therefore,this combined cleanup strategy proved to be effective and environmentally friendly.     

电子受体类型对聚磷污泥胞外聚合物的影响研究

采用3种电子受体(硝氮、亚硝氮、氧),在SBR反应器中分别驯化了具有稳定除磷能力的聚磷污泥。对比研究了不同聚磷污泥胞外聚合物(EPS)的组分与含量,结合三维荧光光谱对EPS中有机物质进行分析。研究表明,以硝氮、亚硝氮为电子受体的聚磷污泥EPS平均浓度较为接近,分别为115.6mg/gVSS、133.5 mg/gVSS,由厌氧段至缺氧段,EPS总浓度有所下降。以氧为电子受体聚磷污泥的EPS平均浓度相对较高,为194.5 mg/gVSS,由厌氧段至好氧段,EPS总浓度略有升高。不同聚磷污泥的EPS组分均以胞外蛋白为主,占EPS总量的53%~65%,多糖与核酸占EPS总量28%~34%、5%~7%。三维荧光光谱显示3种聚磷污泥EPS均具有芳香结构蛋白质、可溶性代谢物的荧光峰,另外,以硝氮为电子受体的聚磷污泥还具有明显的腐殖酸类物质的荧光峰。研究结果表明电子受体对聚磷污泥EPS的组分、浓度、有机质类别有一定的影响。     

藻类水体Cd2+毒性快速监测新方法研究

采用藻类生长抑制试验和光合活性抑制试验两种方法对蛋白核小球藻受不同浓度Cd2+胁迫作用下叶绿素浓度及藻活性荧光参数进行测量,依据Sigmoidal曲线拟合及单因素方差分析(one-way ANOVA)的方法对Cd2+不同胁迫时间下藻活性抑制率和96 h比生长率抑制率的相关性进行研究.结果表明,48、53、72、77和96 h的藻活性抑制率和96 h比生长率抑制率间具有较好的S函数关系(R2>0.95),因此可采用藻活性抑制率48 h-EC10和53 h-EC10来代替96 h的藻类半数比生长率抑制率EC50进行Cd2+藻类毒性实验评价.进一步分析了蛋白核小球藻受Cd2+胁迫48 h和53 h藻活性抑制率和Cd2+毒性当量的剂量-效应关系.该方法为实验室内单一Cd2+毒性的监测提供了一种快速有效的新方法,为水环境综合毒性预警提供了一种切实可行的方法依据.     

Direct evidence of trophic interactions among apex predators in the Late Triassic of western North America

Hypotheses of feeding behaviors and community structure are testable with rare direct evidence of trophic interactions in the fossil record (e.g., bite marks). We present evidence of four predation, scavenging, and/or interspecific fighting events involving two large paracrocodylomorphs (=‘rauisuchians’) from the Upper Triassic Chinle Formation (～220–210 Ma). The larger femur preserves a rare history of interactions with multiple actors prior to and after death of this ～8–9-m individual. A large embedded tooth crown and punctures, all of which display reaction tissue formed through healing, record evidence of a failed attack on this individual. The second paracrocodylomorph femur exhibits four unhealed bite marks, indicating the animal either did not survive the attack or was scavenged soon after death. The combination of character states observed (e.g., morphology of the embedded tooth, ‘D’-shaped punctures, evidence of bicarination of the marking teeth, spacing of potentially serial marks) indicates that large phytosaurs were actors in both cases. Our analysis of these specimens demonstrates phytosaurs targeted large paracrocodylomorphs in these Late Triassic ecosystems. Previous distinctions between ‘aquatic’ and ‘terrestrial’ Late Triassic trophic structures were overly simplistic and built upon mistaken paleoecological assumptions; we show they were intimately connected at the highest trophic levels. Our data also support that size cannot be the sole factor in determining trophic status. Furthermore, these marks provide an opportunity to start exploring the seemingly unbalanced terrestrial ecosystems from the Late Triassic of North America, in which large carnivores far outnumber herbivores in terms of both abundance and diversity.     

滴水湖及其水体交换区沉积物和土壤中PAHs的分布及生态风险评价

采用GC-MS联用技术分析了滴水湖及其水体交换区23个表层沉积物和土壤中16种多环芳烃(PAHs)的含量,探讨其分布特征及来源并对其生态风险进行评价.结果表明,滴水湖沉积物中16种PAHs含量范围是11.49~157.09 ng·g-1,平均含量为66.60 ng·g-1,湖区沉积物中PAHs含量比入湖区低,但比出湖区高.湖区外的沉积物和土壤中PAHs组成主要以中、高分子量PAHs(4环、5~6环)为主,而湖区内表层沉积物中PAHs组成则以低分子量PAHs(2~3环)和高分子量PAHs(5~6环)为主.通过特征化合物分子比值法、主成分分析及多元线性回归模型判源,表明湖区外沉积物和土壤中PAHs来源主要为燃烧源,而湖区内沉积物中PAHs来源为燃烧源和石油类产品泄漏的混合来源.生态风险评价显示,滴水湖及其水体交换区沉积物和土壤中PAHs生态风险较低.     

纳米Fe0粒子对产乙烯脱卤菌群脱氯性能和多样性影响研究

为探讨纳米Fe0粒子对产乙烯脱卤菌群脱氯性能和物种多样性的影响,采用纳米Fe0粒子与产乙烯脱卤菌群联合脱氯,并通过气相色谱、PCR-DGGE和TEM等技术手段进行相关表征.结果表明:当纳米Fe0粒子浓度为0~0.50 g·L-1时,体系的脱氯速率提高较小,低于40%,且菌种数量无明显变化;当其浓度为0.50~1.00 g·L-1时,体系的脱氯速率由0.31μmol·h-1提高到0.77μmol·h-1,体系的脱氯速率提高了60%,部分DGGE条带消失,多样性减少.TEM结果显示,产乙烯脱卤拟球菌在与纳米Fe0粒子接触部位有轻度破损,但细胞没有破裂.纳米Fe0粒子浓度较高时对产乙烯脱卤菌群的脱氯有明显的促进作用,但会使产乙烯脱卤菌群物种多样性减少.