凤眼莲对含银废水的净化研究——动态模拟试验

动态模拟试验结果表明,凤眼莲对含银废水具有很强的净化能力.当污水停留时间为24—48h时,银的净化率达98.6％以上,BOD_5为91.0％,COD_(Cr)为44.6％,浊度为91.1％,总磷(TP)为53.9％,NH_4~+-N为40.4％,NO_2~--N为92.9％,NO_3~--N为37.6％,PO_4~(3-)为56.8％.它与同期运行的活性污泥法相比较,效果要好.     

Exploratory data analysis in the study of 7Be present in atmospheric aerosols

Purpose

Exploratory data analysis (EDA) is applied in this research to study the behavior of radioactive aerosols present in the surface atmosphere of Granada, using ⁷Be as radiotracer. The reason for this study is to reduce the large number of parameters involved in understanding their behavior, given the complexity of the atmosphere.

Methods

Aerosol particles were collected weekly in Granada (Spain) over a 5-year period. Low-background gamma spectrometry was used to determine concentrations of ⁷Be-aerosol activity. The variables studied were: ⁷Be concentration, cosmic ray intensity, temperature, temperature interval, rainfall, relative humidity, and Saharan intrusions. Least significant difference test (LSD), hierarchical cluster analysis (HCA), and principal component analysis (PCA) with varimax rotation have been applied to study the datasets.

Results and discussion

The results of our study reveal that aerosol behavior is represented by two principal components which explain 86.23?% of total variance. Components PC1 and PC2 respectively explain 74.61 and 11.62?% of total variance. PC1 explains the cyclical and seasonal pattern of the samples, while PC2 is related to the production of ⁷Be. In addition, PCA and HCA show good distribution of the samples by families with two groups, summer and winter, at the extremes and spring?Cautumn in the middle. This result corroborates that there are no differences between spring and autumn in the climate of Granada.

Conclusions

EDA has been found to be quite useful in studying the behavior of radioactive aerosols in the surface atmosphere of a city with the climate and geographical characteristics of Granada.     

Highly efficient degradation of ofloxacin by UV/Oxone/Co2+ oxidation process

Introduction

In this study, UV/Oxone/Co²⁺ oxidation process was applied to degradation of ofloxacin (OFL) in the presence of Co²⁺ as the catalytic and Oxone as the oxidant. The operation parameters including pH, temperature, dosages of reagents, and reaction time were studied in detail.

Results

The results showed that the optimum conditions for the UV/Oxone/Co²⁺ processes were determined as follows: temperature?=?25°C, pH?=?5.0, [Oxone]?=?0.6?mmol/L, [Oxone]/[Co²⁺]?=?1,000, and reaction time?=?60?min. Under these conditions, 100% of the OFL degraded. The kinetics was also studied, and degradation of OFL by the UV/Oxone/Co²⁺ process could be described by first-order kinetics.

Conclusions

Mineralization of the process was investigated by measuring the total organic carbon (TOC), and the TOC decreased by 87.0% after 60?min. This process could be used as a pretreatment method for wastewater containing ofloxacin.     

Biota-sediment metal accumulation and human health risk assessment of freshwater bivalve Corbicula fluminea in Dongting Lake,China

In this study, we analyzed the concentrations of metals in sediments and Corbicula fluminea in China’s Dongting Lake to assess the suitability of C. fluminea as an effective biomonitor of metal contamination in sediments and food safety. We analyzed the biota-accumulation capacity by calculating the biota-sediment accumulation factor (BSAF) and assessed the potential human health risk of metals exposure via consumption of C. fluminea using the target hazard quotient (THQ) and total target hazard quotient (TTHQ). The results showed that the average concentrations of As (31.93 mg kg⁻¹), Cd (5.54 mg kg⁻¹), Cr (105.50 mg kg⁻¹), Cu (32.53 mg kg⁻¹), and Zn (207.89 mg kg⁻¹) in sediments were higher than their respective standard set by the General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China. The sediment metals, which were mainly anthropogenic in origin, were at high levels and pose a relatively high ecological risk. Cadium (Cd) showed very high potential ecological risk levels and should be included in the prior pollutants list in the studied area. The mean levels of As (0.81 mg kg⁻¹) in C. fluminea were 1.62-times higher than that set by the National Health Commission of the People’s Republic of China. BSAF values of the soft tissues of C. fluminea were between 0.05 and 2.14, with higher values for Cu (2.14), Cd (1.77), Zn (1.60), and Ni (1.27). Soft tissues of C. fluminea were able to reflect spatial differences in Sr within sediments around Dongting Lake. The results indicated that C. fluminea could be an potential biomonitor for sediment metals assessment in biomonitoring programs, especially for Cu, Cd, Zn, Ni, and Sr. The mean values for THQ and TTHQ of all the analyzed metals were below 1.0, indicating that the intake of metals via comsumption of C. fluminea does not result in an appreciable risk to human health.

     

Evaluation of antibiotic mobility in soil associated with swine-slurry soil amendment under cropping conditions

Interest in identifying pools of antibacterial-resistance genes has grown over the last decade, with veterinary antibiotics (VAs) receiving particular attention. In this paper, a mesoscale study aimed at evaluating the vertical transport of common VAs—namely, fluoroquinolones, tetracyclines, sulfonamides, and lincosamides in agricultural soil subjected to drip irrigation—was performed under greenhouse conditions. Accordingly, leachates of cropped and uncropped soil, amended with swine-slurry leading to 19–38 μg kg^?1 (dry mass) antibiotics in the soil, were analyzed over the course of the productive cycle of a lettuce (42 days) with three sampling campaigns (N?=?24). High lincomycin (LCM) concentrations (30–39 μg L^?1) were detected in the leachates collected from the swine-slurry-amended soil. The highest LCM mass recovered in the leachates (30.1?±?1.63 %) was obtained from cropped experimental units. In addition, the LCM leaching constant and its leaching potential as obtained from the first-order model were higher in the leachates from the cropped experimental units. Lower concentrations of sulfadimethoxine were also detected in leachates and in soil. Enrofloxacin and oxytetracycline occurred only in soil, which is consistent with high soil interaction.     

蒙脱石基絮凝剂处理染料废水

采用先酸活化蒙脱石、再加碱聚合的方法制备了蒙脱石基絮凝剂（PMT），用于去除染料废水的TOC和色度。实验结果表明：PMT处理2BLN分散蓝、KNR活性艳兰、X-3B活性艳红模拟染料废水的最佳加入量分别为0．30。0．30，0．25g／L。在此最佳条件卜，2BLN分散蓝、KNR活性艳兰和X-3B活性艳红模拟染料废水的TOC去除率分别为77．0％，89．2％，39．5％，脱色率分别为41．2％，43．1％，57．4％。PMT对KNR活性艳兰和2BLN分散蓝实际染料废水的TOC去除率高于聚合氯化铝（PAC）和聚合硫酸铁（PFS），分别为91．6％和88．4％。但PMT对X-3B活性艳红实际染料废水的TOC去除率及对3种实际废水的脱色率均低于PAC和PFS。     

可吸附有机卤化物的深度处理实验研究

可吸附有机卤化物（AOX）是人为污染的重要标志之一,北京高碑店污水处理厂二级出水中约90％的AOX为可吸附有机氧化物（AOCl),研究了自氧氧化,粒状活性炭吸附,粉末活性炭吸附3种深度处理工艺对二级出水中AOX的去除作用,臭氧的氧化反应最多可去除约38％的AOX,粒状活性炭床可运行3200床体积,吸附容量为0.14mgAOX/g GH-16型活性炭,投加木质粉末活性炭200mg/L及25mg/L的聚合氯化铝,能去除24．7％的AOX。     

Geomorphological controls of Fraxinus excelsior growth and regeneration in floodplain forests

Geomorphological changes can alter river hydrology and thus influence floodplain forest growth and regeneration. In this paper we quantify the effect of changes in channel elevation at the scale of four decades on hydrological conditions, overbank sediment deposits, water availability, and their impacts on common ash (Fraxinus excelsior) growth and recruitment in floodplain forests of the Ain River, France. Ash is a drought-sensitive species, and its regeneration is influenced by flood disturbance. We compared ash growth between 20 sample plots located in two contrasting geomorphological contexts using dendrochronological measurements: 11 along reaches degrading over the last 80 years and nine along stable or slightly aggrading reaches. In each context, half of the plots were located near the channel, and the remainder were within the floodplain. Ash regeneration was also quantified in each plot. This work showed that sites which undergo channel degradation are associated with less frequent overbank flows. Whereas there is no trend in either the climatic or stream flow timeseries over the last four decades, the growth patterns of ashes of these sites are significantly different as opposed to plots located in stable or aggraded reaches (bell shaped curve vs. constant increase in tree ring width). The variance through time due to climatic or stream flow control is masked by variance due to topographical changes. Currently plots located in degraded reaches show a lower ash growth (mean of 0.20 cm/yr vs. 0.34 cm/yr over the last decade) and less frequent ash seedling establishment. We have identified a hydrologic threshold for ash growth response when stand elevation values reach 1.5-2 m above the mean annual flow stage. Our results confirm that, at a many-decade timescale, changes in channel elevation must be considered in addition to other hydrological controls of hardwood species growth and recruitment.