An experimental investigation on engineering properties of undisturbed loess under acid contamination.

Even though soil acidification can cause significant destabilizing effects on various geotechnical issues, studies have rarely been conducted to determine the influence of soil structure on the impact of acid-contaminated soil. The current work aims to understand the effect of acid fluids on engineering behavior of undisturbed loess through laboratory tests. The sampling site is in a typical region of Loess Plateau, China. The variations in particle size distribution, Atterberg limits, uniaxial compression strength, and permeability were investigated with the help of microstructure for a better understanding of the governing mechanism of undisturbed loess subjected to acid fluids. It was found that exposure to acid fluids can improve the particle size distribution of loess. In contrast, the experimental results indicated that acid fluids can decrease Atterberg limits and strength and permeability of loess, although Atterberg limits and strength of loess are considerably increased in a highly sulfuric acid environment. Then, analyzing the engineering response in the light of microstructure revealed that the face-to-face contacts primarily exist in loess prepared with hydrochloric acid and nitric acid, respectively, whereas the mosaic structure is indeed active in sulfur-contaminated loess. Furthermore, a micro-conceptual structure was proposed based on the experiment led to the conclusion that the cementitious salt and structural characteristics play a dominant role in governing the engineering behavior of loess under acidic conditions.

Sensitivity assessment of denitrifying bacteria against typical antibiotics in groundwater.

The effects of antibiotics on nitrate denitrification in groundwater have acquired growing concern. Denitrification is a microbially mediated process. The effects of antibiotics on denitrification were mainly reflected in denitrifying bacteria. However, little is known about the relationship between antibiotics and denitrifying bacteria. Based on this, both direct antimicrobial susceptibility testing and microbial batch-culture experiments were conducted to assess the influences of typical antibiotics on denitrifying groundwater bacteria, mainly Pseudomonas (46.17%). Denitrifying bacteria, screened from a long-term groundwater denitrification environment, were tested for sensitivity to five typical antibiotics in groundwater: sulfamethoxazole (SMX), erythromycin (ERY), enrofloxacin (ENR), clindamycin (CLI), and tetracycline (TCY). The results showed that the sensitivity of denitrifying bacteria to antibiotics is mainly related to the type and concentration of antibiotics. For antibiotic types, the order of sensitivity by quantitative assessment is ENR > TCY > SMX > ERY > CLI. Fluoroquinolones (FQs) represented by ENR were selected to explore their concentration effects. The influences on denitrifying bacteria were divided into the high concentration effect (500 µg L-1 to 100 mg L-1) and the low concentration effect (100 ng L-1 to 10 µg L-1) with about 100 µg L-1 as a boundary. Exposure to high concentrations had significant inhibitory effects on bacterial growth and exhibited dose dependency, especially for ciprofloxacin (CIP). The low concentration effect was independent of concentration, which may be stimulation or inhibition. The stimulation mainly occurred due to ENR-exposure. For inhibitory effects, Lomefloxacin (LOM) was more effective than other FQs. Especially for inhibition at ng-level exposure, LOM and norfloxacin (NOR) exposures led to the highest and lowest inhibition rates, respectively.

[Characteristics and Genesis of NO3 Type Water in Shallow Groundwater in Liujiang Basin].

In recent years, groundwater nitrate pollution has become more and more severe. Anthropogenic activities have become more significant, not only causing pollution, but also changing the hydrochemical type of groundwater and leading to the emergence of NO3 type groundwater. This study focuses on the Liujiang Basin. The characteristics and influencing factors of NO3 type water in shallow groundwater are analyzed, and the significance of NO3 type water is discussed. Results show that shallow groundwater in the Liujiang Basin is of poor quality and nitrate pollution is severe. NO3 type water comprises 20.9% of all effective data for the area and is mainly distributed in the southeast and a few parts of the northern mountainous area. Based on the characteristics of NO3 type water, this can be classified as high TDS NO3 type water or low TDS NO3 type water. TDS and total hardness concentration values of high TDS nitrate type water are high and the concentration range is wide. Conversely, TDS and total hardness concentration and the concentration range of low TDS NO3type water are both low. The formation of NO3 type water is mainly driven by human domestic sewage, agricultural fertilization, and septic tank and landfill leachate infiltration, among others. The pollution load of high TDS NO3 type water is generally higher than that of low TDS NO3 type water. Analysis of NO3 type water makes it possible to prevent and control groundwater pollution when there is an increasing pollution trend but pollution is not yet severe.

[Screening Method of Priority Control Pollutants in Groundwater Based on Contamination Assessment].

Screening of priority control pollutants is an effective technical means for environmental management and environmental quality protection. Quick and efficient identification of pollutants is useful when attempting to prevent and control groundwater pollution. In order to explore a screening system for a set of priority pollutants that can be applied to regions with weak basic information, a screening method of priority pollutants based on contamination assessment is put forward in this paper. Based on the data of groundwater detection and analysis, using the evaluation method for pollution index classification, and combined with the pollution degree frequency score superposition method. The screening method of priority control pollutants in groundwater based on contamination assessment was established. This method was applied to the screening of pollutants in groundwater in the city of Golmud in Qinghai Province, China. The results were verified by using the screening system based on risk assessment, and the differences in the two systems are discussed. The results show that three categories of 10 kinds of chemical parameters, including TDS, total hardness, chloride, sulfate, sodium, fluorine, total iron, pyrene, phenanthrene, and aluminum, were determined as priority control pollutants in the Golmud region. It was consistent with the results of the screening method based on the risk assessment, and the screening results were reliable. The method based on risk assessment is complex and requires additional basic information, but it has certain foresight and is suitable for regions with abundant basic data. The method based on contamination assessment is simple and convenient and requires less abundant basic data. However, it is easily affected by background values. It is more suitable for the screening of priority control pollutants in regions with weak pollution source information.

[Adsorption of Dissolved Organic Matter with Different Relative Molecular Masses on Inorganic Minerals and Its Influence on Carbamazepine Adsorption Behavior].

In this work, sorption experiments were conducted to understand the adsorption characteristics of dissolved organic matter (DOM) of different relative molecular masses on minerals and the effects of their interaction with PPCPs on the adsorption process. This study chose carbamazepine (CBZ) as the target pollutant, quartz sand as the inorganic mineral, and commercial humic acid (HA) as the DOM. We studied the structural characteristics of HA with different relative molecular masses and the impact of their interaction with CBZ on their adsorption based on dialysis experiments and infrared spectroscopy. It was found that large molecular weight fractions of HA, which contain more hydroxyl, aromatic hydrocarbons, and aliphatic hydrocarbons, were mainly hydrophobic substances, while the smaller fractions, containing more alcohols and carboxyl groups, were mainly hydrophilic substances. The combination of HA and CBZ had two major mechanisms, the combination of amino groups of CBZ and polar functional groups in small molecular weight fractions of HA and hydrophobic interactions between hydrophobic groups and aliphatic or/aromatic compounds in large molecular weight HA. The interaction between CBZ and HA resulted in obvious differences in the adsorption of HA or CBZ. When CBZ does not exist, hydrophobic combinations occurred between HA through the hydrophobic components and quartz sand, which also experienced the exchange coordination reaction with the hydroxyl or carboxyl group of HA. In addition, HA adsorbed the aliphatic and hydrophobic macromolecular components. Quartz sand was used to adsorb the large hydrophobic molecules. When CBZ existed, it adsorbed the small molecular weight fractions of HA. The maximum HA adsorption capacity of quartz sand decreased. CBZ could be adsorbed on quartz sand by hydrophobic interaction, van Edward forces, and polarity interactions in the absence of HA. When adding HA, the adsorption increment of carbamazepine on quartz sand was due to the co-adsorption or accumulation of HA and CBZ after their combination.

[Geochemical Characteristics and Genesis Analyses of High-arsenic Groundwater in the Pearl River Delta].

To determine the main factors affecting the migration, enrichment, and sources of arsenic in the shallow groundwater of the Pearl River Delta (PRD), clustering analysis was used to partition the study area and then analyze the abnormal distribution of arsenic and groundwater storage environment in each part area based on the data obtained from the investigation of groundwater pollution in the PRD region. The results showed, in the study area, arsenic was mainly represented by As(Ⅲ), and its concentration ranged from under the detection limit to 560 µg·L-1. High-arsenic groundwater was mainly distributed in the plain area covered by Quaternary loose sediment, with the Shunde District in Foshan City having the highest, followed by Zhongshan City and central Guangzhou. The hydrochemical type of groundwater in the study area was mainly HCO3-Ca type water. The high-arsenic groundwater had the characteristics of high pH value; high concentrations of NH4+, Fe, and Mn; and a high permanganate index, in addition to a low concentration of NO3-. Based on scatter plot and factor analysis of various indicators of arsenic in groundwater and the impact of human activities on the groundwater environment of the PRD, it was concluded in this study that under the common influence of natural sedimentary environment and pollution input, a neutral or weak-alkaline-reducing environment, which was conducive to the occurrence of high-arsenic groundwater, was formed in the plain area. The role of microorganisms and the input of organic pollutants in the shallow groundwater led to the reduction and dissolution of arsenic-containing Fe-Mn oxide, resulting in the release of arsenic. The source of arsenic contamination in the groundwater was mainly the industrial pollution in Shunde and other areas in southern Foshan City.

Cytotoxicity of chemical constituents from Torricellia tiliifolia DC. on Spodoptera litura (SL-1) cells.

In this study, we evaluated cytotoxicity of chemicals isolated from Torricellia tiliifolia DC. on Spodoptera litura (SL-1) cell line. Among the isolated compounds, 4-hydroxy-3-methoxycinnamaldehyde, 3,5-dimethoxy-4-hydroxycinnamaldehyde, and syringaresinol inhibited SL-1 cell survival in both dose- and time-dependent manners. Meanwhile, the in vivo insecticidal activity test revealed that 4-hydroxy-3-methoxycinnamaldehyde and 3,5-dimethoxy-4-hydroxycinnamaldehyde showed obvious insecticidal activities. These two compounds exhibited toxicity to SL-1 cells by inducing cellular morphological changes including shape change, cell shrinkage, vacuolation, cell membrane blebbing and chromatin condensation and apoptosis. 4-hydroxy-3-methoxycinnamaldehyde and 3,5-dimethoxy-4-hydroxycinnamaldehyde showed the most effect on mitochondrial membrane depolarization at 24h and 72h respectively and induced the apoptosis at a late time point 72h. Our results suggest that 4-hydroxy-3-methoxycinnamaldehyde and 3,5-dimethoxy-4-hydroxycinnamaldehyde inhibit SL-1 survival by inducing apoptosis.

Identifying and assessing human activity impacts on groundwater quality through hydrogeochemical anomalies and NO3-, NH4+, and COD contamination: a case study of the Liujiang River Basin, Hebei Province, P.R. China.

In the face of rapid economic development and increasing human activity, the deterioration of groundwater quality has seriously affected the safety of the groundwater supply in eastern China. Identifying and assessing the impact of human activities is key to finding solutions to this problem. This study is an effort to scientifically and systematically identify and assess the influence of human activities on groundwater based on irregularities in hydrochemical properties and water contamination, which are considered to directly result from anthropogenic activity. The combination of the hydrochemical anomaly identification (HAI) and the contaminant identification (CI) was proposed to identify the influence of human activities on groundwater quality. And the degree of abnormality was quantified by the background threshold value. The principal component analysis (PCA) and land use map were used to verify the reliability of the identification result. The final result show that the strong influence areas mainly distributed in the south of the basin and the affected indicators contained the major elements and NO3-, NH4+, COD. Impacts from anthropogenic activities can be divided into two types: mine drainage that disrupts natural water-rock interaction processes, agricultural cultivation, and sewage emissions that contribute to nitrate pollution.

Occurrence, distribution, and attenuation of pharmaceuticals and personal care products in the riverside groundwater of the Beiyun River of Beijing, China.

This study investigated the occurrence, seasonal-spatial distribution characteristics, and attenuation process of 15 pharmaceuticals and personal care products (PPCPs) in riverside sections of Beiyun River of Beijing. The overall PPCP levels both in surface water and riverside groundwater were moderate on the global scale, and showed higher concentrations in the dry season mainly caused by water temperature variation. Caffeine (CF), carbamazepine (CBZ), metoprolol (MTP), N,N-diethyl-meta-toluamide (DEET), diclofenac (DF), bezafibrate (BF), and gemfibrozil (GF) were seven representative PPCPs, because the rest eight studied compounds occurred in low concentrations and less than 15% of the total concentration of PPCPs. Caffeine and bezafibrate, respectively, was the most abundant compound in surface water and riverside groundwater, with median concentrations of 3020.0 and 125.0 ng L-1. Total concentrations of PPCPs in surface water were much higher than those in the riverside groundwater spatially. Attenuation of PPCPs during riverbank filtration was largely depending on the sources, site hydrogeological conditions, and physical-chemical properties of PPCPs, also was influenced by dissolved organic matter and environmental physicochemical parameters. CF, MTP, DEET, and CBZ were potential groundwater attenuation contaminants; DF, BF, and GF were groundwater-enriched contaminants based on their removal rates. Predominant removal mechanism of PPCPs like CF was biodegradation. Attenuation simulation showed that the one-way supply between Beiyun River and riverside groundwater, and further confirmed Beiyun River, was the main source of pharmaceutical compounds in the riverside groundwater.

[Comparison and Analysis of the Quantitative Methods for Pollutant Sources Load in Groundwater Contamination Risk Assessment].

Groundwater contamination risk assessment is an important basis for the protection of groundwater resources and the prevention and control of groundwater pollution. Its evaluation system is usually composed of three elements, which is vulnerability, pollutant source load and groundwater value. The pollutant source load plays an important role in risk assessment. Because of the difference among methods for pollutant sources load quantification, there will inevitably be different demand for the basic information survey on pollutant sources, as well as unknown impact on the final assessment results. In order to explore the impact of quantitative methods for pollutant sources load on groundwater contamination risk assessment, a case study was conducted in the mesoscale region of alluvial fan in Hutuo River, China. The two representative methods of grading index and quantitative index assessment systems were applied to quantify the pollutant sources load, in combination with the same vulnerability and groundwater value. The results constructed from different risk assessment systems were compared. The results showed that there were great differences between the two methods of quantification for pollutant sources load, and the result of contamination risk assessment also revealed significant differences in the feature of risk valve and the spatial distribution of the risk levels. The results of contamination risk assessment were strongly influenced by the choice of quantification for pollutant sources load methods. The grading index method was suitable for large scale region with lower precision of basic information and was simple, and the results of assessment had relatively lower reliability. The quantitative index method was suitable for the mesoscale and micro-scale region with higher precision of basic information and was relatively complicated, and the results of assessment had relatively higher reliability. It was shown that the scale effect of evaluation region had an important influence on the choice of methods.

[Comparison of Identification Methods of Main Component Hydrochemical Anomalies in Groundwater: A Case Study of Liujiang Basin].

Identification of chemical composition anomalies in groundwater is an important basis for establishing groundwater background values and quantifying the degree of influence of human activities. The main component anomaly identification by five kinds of hydrochemical diagrams has achieved good results in the past. However, this method is too complex to be used widely. In order to simplify the five kinds of hydrochemical diagrams, the Durov diagram was used to replace the five kinds of hydrochemical diagrams to identify the main component anomalies of groundwater, with the Liujiang basin employed as a verification example. The effects of seven kinds of anomaly identification methods combined by hydrochemical diagrams and mathematical statistics methods were compared, and the reliability of these methods were tested in the study. The result indicated that the combination of mathematical statistics and hydrochemical diagrams method can identify the groundwater anomalies better than either used alone. The method of the Pauta criterion+five kinds of hydrography diagrams and the Pauta criterion+the Durov diagram were the best to identify the major component anomalies of groundwater. This shows that the Durov diagram can effectively replace the five kinds of hydrochemical diagrams for anomaly recognition of groundwater, which not only preserves the scientificity of hydrochemical anomaly identification, but also greatly simplifies the process of calculation.

Abnormal pH elevation in the Chaobai River, a reclaimed water intake area.

The pH is a primary index reflecting water quality in rivers. The Jian River and Chaobai River are two reclaimed water intake areas which have elevated pH. This elevated pH has a marked effect on both the phytoplankton, species in water and vegetation on the shore. Understanding the main reasons causing pH elevation in river water has important implications for river ecosystem management and the improvement of water quality and can provide a theoretical basis for the direction of water quality improvement. For this reason, each biogeochemical and physical process influencing pH changes in water was quantified along the flow direction in the Wenyu to Chaobai reclaimed water diversion project, in which proton consumption and production by such processes were monitored and calculated at five monitoring sections. The calculations indicated that photosynthesis and denitrification were the primary reasons for the increase of pH in the Jian River and Chaobai River. Oppositely, carbonate precipitation and sediment decomposition restricted the increase of pH in both rivers. In addition, CO2 emission to the air also promoted a increase of pH in the Jian River, while CO2 absorption from the air restricted the increase of pH in the Chaobai River. NO3- nitrogen in reclaimed water was not efficiently removed and the reclaimed water flow condition in the intake area created favorable conditions for photosynthesis of algae breeding and denitrification by microorganisms. Therefore, biogeochemical and physical processes that promoted the increase of pH were greater than inhibiting processes and the pH gradually increased along the flow direction. The contribution rates of photosynthesis and denitrification for the increase of pH were 55.48 and 27.09%, respectively, in the Jian River and 78.08 and 21.92%, respectively, in the Chaobai River. In addition, CO2 emission contributed 17.43% of the increase in pH in the Jian River.

[Distribution Characteristics and Potential Ecological Hazards Assessment of Soil Heavy Metals in Typical Soil Profiles in Southeast Suburb of Beijing].

To investigate the distribution characteristics and the potential ecology risk of different types of heavy metals, soil samples were collected from various stratigraphic sections in the southeastern suburb of Beijing, where soil heavy metal (Cu, Pb, Cr, As) contents were measured and analyzed using multivariate statistical analysis and the potential ecological risk index method. The results showed that the concentrations of the four heavy metals followed the order of Cr > Cu > As > Pb with variable coefficients ranging from 59.60% to 159.33% at 3-6 m stratum, which all displayed a high degree of variability. The concentrations of Cu and Pb were positively correlated with soil organic matter (SOM), cation exchange capacity (CEC), etc, with higher eigenvalues in Factor 1 and 2, demonstrating the impact of organic colloid on the occurrence of heavy metals. The risk level of the specific heavy metal followed the order of As > Cu > Pb > Cr, where As already showed a medium potential ecological risk in the studied area.

[Simulation Experiment: Effect of Organic Colloid on Carbamazepine Transport in Porous Media].

The behavior of organic contaminants in subsoil can be affected by their interactions with organic colloids. In order to explore the impact of organic colloids on the mobility of emerging contaminants in porous media, especially pharmaceutical and personal care products (PPCPs), column experiment was conducted to investigate the migration behavior of target compound carbamazepine (CBZ). In the experiments, quartz sand, standard soil and natural field-collected soil were selected as three types of porous media respectively, and organic colloids were prepared with commercial humic acid. The results showed that, the two-site chemical nonequilibrium model in CXTFIT could better describe the migration behavior of CBZ in all soil columns. This results demonstrated that chemical nonequilibrium adsorption happened in CBZ's migration process. After colloid was added to the sand column, results of CBZ's adsorption process had no significant changes, however, desorption hysteresis was weaker. The reason for that can be explained as the formation of colloid-CBZ complexes by the combination of colloid with CBZ. These complexes could not significantly influence CBZ's adsorption process, however, they could accelerate CBZ's desorption process by solubilization. When organic colloids existed, the migration of CBZ in natural soil and standard soil columns was more hysteretic than sand column, indicating that the sorption capacity of soil column was higher than sand column. The soil organic matter and clay should play a crucial role in the transportation: low/high energy adsorption sites in organic matter and clay surface all could bond with CBZ. Compared with standard soil, the magnitude of sorption and desorption hysteresis of CBZ in natural soil was higher. It was mainly because of the higher organic content in natural soil. Based on the migration behavior of the contaminant in this study, a concept model for various interactions during the transport of hydrophobic organic contaminants in porous media in the presence of organic colloids was then proposed.

[Comparative analysis of two different methods for risk assessment of groundwater pollution: a case study in Beijing plain].

Groundwater contamination risk assessment has important meaning to groundwater contamination prevention planning and groundwater exploitation potentiality. Recently, UN assessment system and WP assessment system have become the focuses of international research. In both systems, the assessment framework and indices were drawn from five aspects: intrinsic vulnerability, aquifer storage, groundwater quality, groundwater resource protection zone and contamination load. But, the five factors were built up in different ways. In order to expound the difference between the UN and WP assessment systems, and explain the main reasons, the UN and WP assessment systems were applied to Beijing Plain, China. The maps constructed from the UN and WP risk assessment systems were compared. The results showed that both kinds of groundwater contamination risk assessment maps were in accordance with the actual conditions and were similar in spatial distribution trends. However, there was quite significant different in the coverage area at the same level. It also revealed that during the system construction process, the structural hierarchy, relevant overlaying principles and classification method might have effects on the groundwater contamination risk assessment map. UN assessment system and WP assessment system were both suitable for groundwater contamination risk assessment of the plain, however, their emphasis was different.

[Forming mechanism of humic acid-kaolin complexes and the adsorption of trichloroethylene].

The interaction between soil organic components and mineral components was explored in this study. Humic acid and kaolin were used for the preparation of organic-mineral complexes with different contents of organic matter, for experimental study of the adsorption of trichloroethylene. The results showed that the adsorption of trichlorethylene fitted the Freundlich isotherm model. The existence of interaction between humic acid and kaolin was indicated by the significant difference between the actual value and the theoretically overlaid value of the adsorption capacity. With various characterizations, such as FTIR and surface area & pore analysis, the mechanism of interaction between humic acid and kaolin was suggested as follows. When their contents were low, humic acid molecules firstly loaded on the surface binding sites of kaolin. Then with the content increased, as O/M( organic-mineral mass ratio) was 0.02-0.04, some surface pores of kaolin were filled by part of the molecules. After reaching a relatively stable stage, as O/M was 0.04-0.08, humic molecules continued to load on the surface of kaolin and formed the first humic molecule-layer. With humic acid content continued increasing, as O/M was 0.08-0.10, more humic molecules attached to kaolin surface through the interaction with the first layer of molecules and then formed the second layer. O/M was 0.10-0.16 as the whole second layer stage, meanwhile the first layer was compressed. Then when O/M was 0.16-0.4, there were still some humic loadings onto the second layer as the third layer, and further compressed the inner humic acid layers. Besides, some humic acid molecules or aggregates might go on attaching to form as further outer layer.

[Distribution Characteristics of Fluoroquinolones Antibiotics in Surface Water and Groundwater from Typical Areas in A City].

In order to investigate the characteristics of 5 typical kinds of fluoroquinolones (FQs) pollution in waters from a city, surface water and groundwater samples from main drainage rivers and typical areas were collected, respectively. The conventional test and FQs concentrations analysis of the water samples were conducted. The results showed the concentration and composition of FQs in groundwater differed substantially from those in surface water. The average concentration of FQs in surface water was 789.1 ng x L(-1) with the main components of ofloxacin (OFL) and lomefloxacin (LOM). This value was higher than the average concentration of FQs in groundwater: 342.7 ng x L(-1) with the main components of norfloxacin (NOR) and lomefloxacin (LOM). The enrofloxacin (ENR) exhibited relatively lower levels in both surface water and groundwater as compared to others. The highest FQs concentrations in surface water were found in trenches, followed by tributaries and the main stream. For groundwater, FQs concentrations were relatively higher in the sewage riverside. A decreasing trend of FQs concentration was monitored with the increasing distance of sampling points to the drainage rivers and all components mentioned above showed similar changing trends. The results of this study preliminarily indicated that FQs in groundwater along the riverside probably came from the surface water.

[Simulation of nitrate pollution in groundwater using pump-and treat optimization method].

To study the groundwater polluted by nitrate in a landfill site in Beijing, with the pump-and-treat technology, genetic algorithms (GA) and simulated annealing (SA) were used to optimize the cases of 18 planned pumping wells in the groundwater nitrate plume. The optimization method was run to determine the minimum total costs, as a result of the optimal number of wells with the optimal locations and pumping rates. The results of optimization showed that, both GA and SA optimization conditions could reach the desired results, which means that the concentration of nitrate could be reduced to 10 mg x L(-1) after 100 days pumping. However, under the GA optimization conditions, the pumping rates of well 8 and well 14 were 155 m x d(-1) and 10 m3 x d(-1), respectively. In contrast, under the SA optimization conditions, the pumping rate of well 8 was 82 m3 x d(-1), and that of well 14 was 39 m3 x d(-1). Based on the GA and SA optimized pumping rate, the total mass removal rates of nitrate were 76.89% and 84.92%, respectively. The results showed that the best location of the well was in the central axis of either midstream or downstream of the nitrate contamination plume. The pumping rate of midstream was larger than downstream. Comparison of the two optimization algorithms showed that the optimized system management cost of SA was 6.8%, which was lower than that of GA. Meanwhile, SA was easily convergent with smaller volatility.

[Contamination characteristics of fluoroquinolones in different kinds of soil profiles in Southeast suburb of Beijing].

Eighty-six soil samples were collected using Geoprobe soil sampler from 11 borehole profiles of Beijing Southeast suburb. The sampling sites could be divided into 8 kinds of landuse. Physical and chemical properties of samples were analyzed. The concentrations of 5 fluoroquinolones (FQs) were analyzed by the high-performance liquid chromatography. Results show that the average value of total concentrations of 5 FQs is 46.1 µg x kg(-1). Ofloxacin (OFL) is the predominant among them, and then is norfloxacin (NOR). Last comes to enrofloxacin (ENR), ciprofloxacin (CIP) and lomefloxacin (LOM). There are significant differences in FQs concentrations and kinds among the 8 land use types of soil profiles. The average value of total concentrations of 5 FQs decrease with an increasing of soil depth. The average concentration of OFL, NOR, LOM and ENR decrease with an increasing of soil depth. But CIP has the opposite result. Based on FQs concentrations from 42 soil samples with a depth among 0 to 3 meters, contamination characteristics of FQs were analyzed by fuzzy hierarchial clustering. Sampling sites of vegetable greenhouse, woods, sewage irrigation zone, groundwater irrigation zone, livestock and poultry farm, sediments from sewage river have similar components and contents of FQs, with less kinds and low concentration. In contrast, sampling sites of pharmaceutical enterprises and refuse landfill have more kinds and medium concentration of FQs.

Surgical treatment for posterior rim separation of the lumbar and sacral vertebrae.

OBJECTIVE: The posterior rim separation of the lumbar and sacral vertebrae has been ascribed to various mechanisms. The procedure of operative treatment is still controversial. The authors' objective was to study the therapeutic methods of posterior vertebral rim separation. METHODS: Thirty-four patients, including 23 males and 11 females whose ages ranged from 24 to 65 years (mean 41.3 years), were treated for posterior vertebral rim separation by various methods. All patients had discectomy and removal of bony fragment. Wide fenestration or hemilaminectomy was performed for 24 type I-III lesions, laminectomy for four type II and one type III lesion, and bilateral fenestration for 5 of 17 type II lesions. Posterior lumbar interbody fusion (PLIF) was performed in 11 patients using autogenous iliac bone or poly (ether-ether-ketone) (PEEK) spacer implant. RESULTS: Follow-up studies were performed for all patients ranging from 11 months to 4.6 years with an average period of 2.7 years. There were no serious intra-operative or postoperative complications. Satisfactory results were achieved in all patients except two with type III lesions, mostly because of a long history of hypaesthesia of the leg and a drop foot. Eleven patients who had PLIF exhibited bony fusion at final follow-up. CONCLUSIONS: Early operative treatment should be performed on patients after a brief trial of conservative treatment. A proper surgical operation must be based on the type and location of the separated bony fragment and clinical symptoms.