Characterization and evaluation of the leachability of bottom ash from a mobile emergency incinerator of COVID-19 medical waste: A case study in Huoshenshan Hospital, Wuhan, China.

To dispose of the medical waste generated during the COVID-19 pandemic, a new type of mobile emergency incinerator (MEI) was used in Huoshenshan Hospital, Wuhan, China, and consequently, it produced a number of medical bottom ashs (MBAs). In this study, the characterization and environmental risk evaluation of these MBAs were conducted to evaluate the disposal effect of this MEI used during the pandemic. Three types of leaching tests, EN 12457-2, TCLP 1311, and HJ/T 299-2007, were compared to investigate the release behaviors of major and trace elements from these MBAs. Lack of detection of COVID-19 in MBAs showed that this mobile emergency incinerator could thoroughly eliminate the COVID-19 virus in medical wastes to avoid secondary transmission. The results indicated that the increasing usage of chlorinated disinfectants and physiological saline solutions resulted in high Cl contents in MBAs. In addition, the increasing usage of polypropylene (PP) products changed the chemical properties and compositions of MBAs, with Ca as the main element. The leachability investigation revealed that the main metals in leachates were Ca, Na and K, and the toxic heavy metals such as Zn, Pb, Cu, and Cr in MBAs were difficult to extract because of the high pH (>12) of these MBAs. This study could provide consultation for the treatment and management of MBAs produced from MEIs dealing with emergent infectious diseases such as COVID-19.

Fir bark modified by Phanerodontia chrysosporium: A low-cost amendment for cd-contaminated water and agricultural soil.

In this study, a modified fir barks (MFB) was prepared by mixing fir barks (FB) and white-rot fungi (Phanerodontia chrysosporium) under aerobic fermentation. The potential of MFB for Cd2+ adsorption was investigated by batch experiments combined with kinetic, isotherm, and thermodynamics analyses. The results revealed that the modification greatly increased the porous structures on the surfaces of fir barks and the surface area of MFB was much higher than that of FB. As a result, the adsorption capacity of Cd2+ on MFB (17.4 mg g-1) was more than two times higher than that on FB (7.2 mg g-1), and the adsorption of Cd2+ on MFB was controlled by physisorption and chemisorption. The immobilization of Cd by MFB in a contaminated agricultural soil was also investigated. The effect of MFB on the bioavailability of Cd was investigated using a leaching test (the European standard EN 12457-2) combined with a typical sequential extraction procedure (the community bureau of reference, BCR). The experimental results showed that the Cd leachability was reduced by 71% when the added MFB dosage was 30 mg g-1. Besides, the MFB amendment could transform Cd from unstable geochemical fractions into more stable fractions. In total, the MFB, as a chemical-free and eco-friendly material, could be potentially employed for in-situ remediation of Cd-contaminated agricultural soils.

Efficient Degradation of 2,4-Dichlorophenol on Activation of Peroxymonosulfate Mediated by MnO2.

Sulfate radical based-advanced oxidation process has received increasing interest in the remediation of wastewater and contaminated soil. In this study, degradation of 2, 4-dichlorophenol (2, 4-DCP) was investigated over peroxymonosulfate (PMS) activation by MnO2, which was prepared by liquid-phase oxidation method. The prepared MnO2 was characterized by transition electron microscopy, X-ray diffraction, N2 adsorption-desorption, and X-ray photoelectron spectroscopy. Characterization results showed that α-MnO2 exhibited the highest surface area and Mn (III) content. The PMS activation by MnO2 in 2, 4-DCP degradation followed the order of α-MnO2 > γ-MnO2 > ß-MnO2, which is dependent on the properties of MnO2 including crystal structure, surface area and Mn (III) content. Influences of initial concentration of 2, 4-DCP, PMS and MnO2 dosage, pH and co-existing inorganic ions on the degradation were examined. Electron paramagnetic resonance (EPR) and quenching experiments with ethanol and tert-butanol suggested that sulfate radicals were the dominant radicals in the process. Findings in this study indicated that α-MnO2 was an attractive catalyst for activation of PMS to degrade 2, 4-DCP in aqueous solution.

Response of microbial communities in aquifers with multiple organic solvent contamination: Implications for MNA remedy.

The application of Monitored Natural Attenuation (MNA) technology has been widespread, while there is a paucity of data on groundwater with multiple co-contaminants. This study focused on high permeability, low hydraulic gradient groundwater with co-contamination of benzene, toluene, ethylbenzene, and xylenes (BTEX), chlorinated aliphatic hydrocarbons (CAHs), and chlorinated aromatic hydrocarbons (CPs). The objective was to investigate the responses of microbial communities during natural attenuation processes. Results revealed greater horizontal variation in groundwater microbial community composition compared to vertical variation. The variation was strongly correlated with the total contaminant quantity (r = 0.722, p < 0.001) rather than individual contaminants. BTEX exerted a more significant influence on community diversity than other contaminants. The assembly of groundwater microbial communities was primarily governed by deterministic processes (ßNTI < -2) in high contaminant concentration zones, while stochastic processes (|ßNTI| < 2) dominated in low-concentration zones. Moreover, the microbial interactions shifted at different depths indicating the degradation rate variation in the vertical. This study makes fundamental contribution to the understanding for the effects of groundwater flow and material fields on indigenous microbial communities, which will provide a scientific basis for more precise adoption of microbial stimulation/augmentation to accelerate the rate of contaminant removal.

Determining priority control toxic metal for different protection targets based on source-oriented ecological and human health risk assessment around gold smelting area.

Determining the priority control source and pollutant is the key for the eco-health protection and risk management around gold smelting area. To this end, a case study was conducted to explore the pollution characteristics, source apportionment, ecological risk and human health risk of toxic metals (TMs) in agricultural soils surrounding a gold smelting enterprise. Three effective receptor models, including positive matrix factorization model (PMF), ecological risk assessment (ERA), and probabilistic risk assessment (PRA) have been combined to apportion eco-human risks for different targets. More than 95.0% of samples had a Nemerow pollution index (NPI) > 2 (NPImean=4.27), indicating moderately or highly soil TMs contamination. Four pollution sources including gold smelting activity, mining source, agricultural activity and atmosphere deposition were identified as the major sources, with the contribution rate of 17.52%, 44.16%, 13.91%, and 24.41%, respectively. For ecological risk, atmosphere deposition accounting for 30.8% was the greatest contributor, which was mainly loaded on Hg of 51.35%. The probabilistic health risk assessment revealed that Carcinogenic risks and Non-carcinogenic risks of all population were unacceptable, and children suffered from a greater health risk than adults. Gold smelting activity (69.2%) and mining source (42.0%) were the largest contributors to Carcinogenic risks and Non-carcinogenic risks, respectively, corresponding to As and Cr as the target pollutants. The priority pollution sources and target pollutants were different for the eco-health protection. This work put forward a new perspective for soil risk control and management, which is very beneficial for appropriate soil remediation under limited resources and costs.

Contaminant characterization at pesticide production sites in the Yangtze River Delta: Residue, distribution, and environmental risk.

The Yangtze River Delta (YRD) is the largest pesticide-producing region in the world. Contamination of pesticide production sites has always been a focus of public attention. Twenty pesticide production sites in YRD were selected to analyze the residue, distribution, and environmental risk of organic contaminants in soil and groundwater. A total of 194 organic chemicals were detected in all soil and groundwater samples from the 20 sites. Eighty-eight constituents of concern (COCs) exceeded the comparison values of Regional Screening Levels (RSLs), and 80 % exceeded the RSLs by more than five times. The toxic effects of COCs in soil and groundwater were dominated by the carcinogenic risk, referred as "non-threshold". Benzene toluene ethylbenzene & xylene (BTEX) and chloroaliphatic hydrocarbons (CAHs) were the most prevalent at pesticide sites in YRD rather than pesticides, followed by chlorobenzene, chlorophenols, and polycyclic aromatic hydrocarbons (PAHs). CAHs and BTEX could penetrate up to 24 m, while the others were primarily limited to 12 m. Most pesticide production sites showed a great contamination depth of >8 m, some even deeper than 20 m, posing a great risk of contamination to the confined aquifer. Due to the close interconnection of soil with water bodies, the shallow groundwater and adjacent surface water resources are also susceptible to suffering from environmental risk. More than half of the pesticide production sites in the YRD consist primarily of low-permeable clay layers, making in-situ contamination remediation difficult. This study provides a basis for developing remediation technology for pesticide sites in YRD and an ecological reference for further cleaning production and green manufacturing in the pesticide industry.

Antimony (Sb) pollution control by coagulation and membrane filtration in water/wastewater treatment: A comprehensive review.

Antimony (Sb) pollution in the water environment caused by the large-scale mining of Sb ore and the wide use of Sb-containing products seriously endangers human health and poses a great threat to the ecological environment. Coagulation is one of the most cost-effective technologies for Sb pollution control in water/wastewater treatment and has been widely used. However, a comprehensive understanding of Sb pollution control by coagulation, from fundamental research to practical applications, is lacking. In this work, based on the current status of Sb pollution in the water environment, a critical review of the Sb removal performance and mechanism by coagulation and related combined processes was carried out. The influencing factors of Sb removal performance by coagulation are introduced in detail. The internal mechanisms and improvement strategies of Sb removal by oxidation/reduction-coagulation and coagulation-membrane filtration technologies are emphasized. Moreover, given the development of Sb-removing coagulants and the resource utilization of Sb-containing sludge, future perspectives of coagulation for Sb removal are discussed. As the first review in this field, this work will illuminate avenues of basic research and practical applications for Sb and Sb-like pollution control in water/wastewater treatment.

Assessing the environmental impacts and costs of biochar and monitored natural attenuation for groundwater heavily contaminated with volatile organic compounds.

Although biochar (BC) and monitored natural attenuation (MNA) are regarded as green technologies for remediating volatile organic compounds (VOCs) contaminated groundwater, their life cycle environmental impacts and costs have not been systematically quantified. This work assessed the primary and secondary environmental impacts and the cost of three options for remediating the groundwater at a closed pesticide manufacturing plant site, which was contaminated by high levels of multiple VOCs and is undergoing MNA. The studied options include a combination of MNA and BC (MNA + BC), BC, and pump and treat (PT). The environmental impacts were examined through a Life Cycle Assessment (LCA) using the ReCiPe 2016 method. The costs were evaluated using a Life Cycle Cost (LCC) method created in the SimaPro. The LCA results show that the overall environmental impacts follow the sequence of PT > BC > MNA + BC, but MNA + BC shows evident primary impacts. The CO2 eq emissions generated from PT are more than five times of MNA + BC or BC. The cement, electricity, and steel for construction, and the operation energy are the environmental hotspots in PT. In MNA + BC and BC, the electricity for feedstock pyrolysis is the environmental hotspot, while the use of BC by-products to generate heat and power has positive environmental credit that compensates other negative environmental burdens. Incorporating institutional controls, using renewable energy and recycled or alternative materials, and developing BC with superior adsorption capacity are recommended to optimize the remediation strategies. The LCC results show that PT renders the highest cost, with cement and electricity being the two most expensive items. Electricity is the dominant contributor to the costs of MNA + BC and BC, while the avoided heat and power generation can save the cost of other items. Overall, this study provides scientific support to develop and optimize green remediation solutions for VOCs contaminated groundwater.

A new insight into the influencing factors of natural attenuation of chlorinated hydrocarbons contaminated groundwater: A long-term field study of a retired pesticide site.

Natural attenuation of contaminants has been increasingly applied as a strategy to manage the retired pesticide manufacturing sites due to the increasing restrictions on the reuse of contaminated sites in China. However, the influencing factors to enhance natural attenuation for chlorinated hydrocarbons in retired pesticide sites were not well studied. In this paper, monitoring of pollutants, environmental factors and microbial community was conducted from 2016 to 2021 in a retired pesticide site in Jiangsu Province undergoing natural attenuation, where the groundwater was severely contaminated with chlorinated hydrocarbons. The spatial variation of main pollutants, including chlorinated ethenes and ethanes, indicated that the site could be divided into the source area, diffusion area, and the end of diffusion area, where organohalide-respiring bacteria (OHRB) were detected. Pollutants and environmental factors influenced the OHRB community structure, which explained 7.6% and 33.2% of the variation, respectively. The abundances of obligate and facultative OHRB were affected in opposite ways by pollutants and environmental factors. Dehalococcoides and Dehalogenimonas in obligate OHRB were significantly inhibited by sulfate (r = -0.448, p < 0.05). The spatial-temporal characteristics of pollutants and the reveal of microbial community structure and its restricting factors in different areas make the foundation for strengthening the implementation of natural attenuation.

Adsorption of three pesticides on polyethylene microplastics in aqueous solutions: Kinetics, isotherms, thermodynamics, and molecular dynamics simulation.

Microplastics could act as a carrier for pesticides in the water environment and pose a potential risk. This study mainly investigated the effects of reaction time, microplastics dosages, pH, and NaCl salinity on the adsorption characteristics of three pesticides (Imidacloprid, Buprofezin, Difenoconazole) on polyethylene (PE) microplastics in aqueous solution. The results showed that high pH and low NaCl salinity were conducive to the adsorption. The adsorption data were well fitted by the Freundlich isotherm model and the pseudo-first-order kinetics, indicating that it was mainly controlled by physical function. The adsorption capacity of three pesticides on PE microplastics followed the order of Difenoconazole > Buprofezin > Imidacloprid. The thermodynamic study indicated the adsorption of all pesticides as spontaneous and exothermic processes, and the elevated temperature was favorable to the adsorption. SEM-EDS and FTIR results verified that pesticides were adsorbed on the microplastics but the adsorption process was mainly controlled by intermolecular Van Der Waals Force and the microporous filling mechanism. Grand Canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulation results indicated that surface adsorption was the exclusive mechanism for the adsorption of pesticides on microplastics, and the final adsorption configurations revealed that there were complex interactions between the pesticide molecules and the C, H atoms in PE molecules. The results of this study illustrated that PE microplastics are potential carriers for pesticides in the water environment.

Rapid Degradation of Nitrochlorobenzene by Activated Persulfate Oxidation With Biochar Supported Nanoscaled Zero Valent Iron.

Although pesticide intermediates are a kind of typical toxic pollutant in contaminated sites, the remediation of these contaminants in groundwater and soils is of limited concern. In the present study we investigated the performance of a novel heterogeneous oxidation system, biochar supported nanoscaled-zero valent iron (nZVI/BC) activated persulfate (PS), in the oxidative degradation of nitrochlorobenzene (NCB), a typical pesticide intermediate. Peanut shell based nZVI/BC was prepared and used as the PS activator. The degradation kinetics of m-, p-, and o-NCB isomers in the aqueous phase were investigated. The effects of BC/nZVI composition (Fe/BC mass ratio), the amount of BC/nZVI and PS, and initial contaminant concentration on NCB removal were also examined. Results suggest that over 90% removals of three NCB isomers could be obtained by the nZVI/BC activated PS system at initial NCB concentration of 10 mg L-1. The combination of nZVI/BC composite and PS showed superior performance to PS alone. The optimal treatment condition was supposed as the Fe: BC ratio of 1:1, Fe amount of 6 mmol L-1, and the mole ratio of Fe to perfulfate of 1:1.

[Heavy Metal Contamination and Health Risk Assessment of Corn Grains from a Pb-Zn Mining Area].

A total of 92 corn grain samples, around the Pb-Zn mining area in Southwest China, were collected to evaluate the contamination and health risk of heavy metals. Heavy metals including Pb, Zn, Cd, Cr, and Ni in samples were analyzed. A single factor pollution index and comprehensive pollution index were calculated to assess the quality of corn grains. The potential health risks to adults and children due to the intake of these heavy metals through consumption of crops were evaluated using the health risk index. The results showed that the average contents of Pb, Zn, Cd, Cr, and Ni in corn grains were 0.30, 23.75, 0.21, 1.33, and 1.15 mg ·kg-1, respectively, Among the metals, the content of Zn, Pb, Cd, Cr, and Ni exceeded the national food hygiene standards. The Nemero index of Pb, Cd, Cr, and Ni ranged from 4.32 to 9.07, indicating an extremely high level, whereas the contamination of Zn reached an alarming level. The assessment results of the comprehensive health risk index for the corn grains indicated that the contamination of heavy metals poses health risks to adults and children by food ingestion; moreover, the children were more sensitive to various heavy metals than the adults. Principle component analysis revealed that the first main component dominated the sources of Pb, Cd, Cr, and Ni, while the second main component, Zn, might have originated from sources different from the other heavy metals. Positive correlations were not observed between the heavy metals in corns and soils.

A review of bacteriophage therapy for pathogenic bacteria inactivation in the soil environment.

The emerging contamination of pathogenic bacteria in the soil has caused a serious threat to public health and environmental security. Therefore, effective methods to inactivate pathogenic bacteria and decrease the environmental risks are urgently required. As a century-old technique, bacteriophage (phage) therapy has a high efficiency in targeting and inactivating pathogenic bacteria in different environmental systems. This review provides an update on the status of bacteriophage therapy for the inactivation of pathogenic bacteria in the soil environment. Specifically, the applications of phage therapy in soil-plant and soil-groundwater systems are summarized. In addition, the impact of phage therapy on soil functioning is described, including soil function gene transmission, soil microbial community stability, and soil nutrient cycling. Soil factors, such as soil temperature, pH, clay mineral, water content, and nutrient components, influence the survival and activity of phages in the soil. Finally, the future research prospects of phage therapy in soil environments are described.

Metaphire guillelmi gut as hospitable micro-environment for the potential transmission of antibiotic resistance genes.

Earthworm gut played an important role in the transformation of various contaminants in the soil environments. With the increasing application of organic fertilizer recently, the ingestion of antibiotics, antibiotic resistance bacteria (ARB), and antibiotic resistance genes (ARGs) made the earthworm gut a potential favorable micro-environment for the transmission of ARGs in the soil. In this work, the conventional plate incubation and high-throughput sequencing methods were both employed to investigate the composition of the cultivable and overall ARB/ARGs in the Metaphire guillelmi earthworm gut. A total of 87 cultivable isolates that resisted tetracycline (TC) and/or sulfadiazine (SD) were obtained, most of which belonged to phylum Firmicutes, genus Bacillus. Meanwhile, the counts of isolates with TC-SD dual resistance were higher than those with sole SD or TC resistance. Moreover, higher ARB counts and diversity were detected in the earthworm gut by high-throughput sequencing technique than those by the classical plate cultivation. Overall, the combination of conventional cultivable bacteria isolation and high-throughput sequencing methods provided a comprehensive understanding of the ARB composition in the earthworm gut. The results demonstrate that the earthworm gut is a hospitable micro-environment for ARB colonization. The potential role of earthworm intestinal ARB and ARGs proliferation in soil environments warrants further research.

Biochar combined with polyvalent phage therapy to mitigate antibiotic resistance pathogenic bacteria vertical transfer risk in an undisturbed soil column system.

The vertical migration of antibiotic resistance pathogenic bacteria (ARPB) and antibiotic resistance genes (ARGs) in the surface soil-vadose soil system has become a new threat to ecological safety and public health; there is an imperative need to develop an efficient technique for targeted control and inactivation of ARPB in these systems. In this work, undisturbed soil columns (0 ∼ -5 m) were constructed to investigate the impact of biochar amendment or/and polyvalent bacteriophage (ΦYSZ-KK) therapy on the vertical control and inactivation of tetracycline-resistant Escherichia coli K-12 and chloramphenicol-resistant Klebsiella pneumonia K-6. The simultaneous application of polyvalent phage and biochar impeded the vertical migration of ARPB from the top soil to lower soil layers and stimulated the ARPB dissipation in the soil column. After 60-day incubation, levels of ARPB and ARGs decreased significantly in the soil column by magnitudes of 2-6. Additionally, high throughput sequencing indicated that the simultaneous application of biochar and phage clearly maintained the structure and diversity of the soil microbial communities (p < 0.05). This work therefore demonstrates that the application of a biochar/phage combination is an environmentally friendly, efficacious measure for the control and inactivation of ARPB/ARGs in vertical soil column systems.

Comparing polyvalent bacteriophage and bacteriophage cocktails for controlling antibiotic-resistant bacteria in soil-plant system.

Antibiotic resistant pathogenic bacteria (ARPB) residual in soil-plant system has caused serious threat against public health and environmental safety. Being capable of targeted lysing host bacteria, phage therapy has been proposed as promising method to control the ARPB contamination in environments. In this study, microcosm trials were performed to investigate the impact of various phage treatments on the dissipation of tetracycline resistant Escherichia coli K-12 and chloramphenicol resistant Pseudomonas aeruginosa PAO1 in soil-carrot system. After 70 days of incubation, all the four phage treatments significantly decreased the abundance of the pathogenic bacteria and the corresponding antibiotic resistance genes (tetW and cmlA) in the soil-carrot system (p < 0.05), following the order of the cocktail phage treatment (phages ΦYSZ1 + ΦYSZ2) > the polyvalent phage (ΦYSZ3 phage with broad host range) treatment > host-specific phage (ΦYSZ2 and ΦYSZ1) treatments > the control. In addition, the polyvalent phage treatment also exerted positive impact on the diversity and stability of the bacterial community in the system, suggesting that this is an environmentally friendly technique with broad applications in the biocontrol of ARPB/ARGs in soil-plant system.

The joint toxicity effect of five antibiotics and dibutyl phthalate to luminescent bacteria (Vibrio fischeri).

Antibiotics and phthalate esters are two kinds of emerging pollutants and are ubiquitous in the aquatic ecosystem. To date, few studies analyzed the combined toxicity of the mixtures of antibiotics and phthalate esters, and their joint toxicity effect mode remains unknown. Here, we investigated the single and joint toxicity of dibutyl phthalate (DBP) and five antibiotics, namely, oxytetracycline hydrochloride (OTC), chlortetracycline hydrochloride (CTC), sulfamethazine (SMZ), sulfamerazine (SMR), and sulfadiazine (SD), to luminescent bacteria of Vibrio fischeri. The median effect concentration (EC50) values of the test chemicals were ranked as CTC (6.67 mg/L) > OTC (25.12 mg/L) > SD (67.61 mg/L) > SMR (141.51 mg/L) > DBP (148.38 mg/L) > SMZ (245.07 mg/L). The joint toxicities of the binary mixtures of antibiotics and DBP were evaluated by the concentration addition (CA) and independent action (IA) models. The joint toxicity effects of CTC-DBP, OTC-DBP, SMZ-DBP, SMR-DBP, and SD-DBP all appeared to be synergism. Our study revealed that sulfonamides combined with DBP could be as toxic as or even more toxic than tetracycline. Thus, the joint toxicity effect should be considered when assessing the ecological risks of binary or multicomponent pollutants.

[Principal Component Analysis and Ecological Risk Assessment of Heavy Metals in Farmland Soils around a Pb-Zn Mine in Southwestern China].

The farmland soil around a Pb-Zn mine in southwestern China was studied. One hundred forty-nine surface soil samples were taken from 0-20 cm depth, and the contents of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were tested. The correlations among these heavy metals were studied with multivariate analysis, and the potential sources of the metals were identified. The environmental risk of the metals was evaluated with the Potential Ecological Risk Index method. The results showed that the amounts of Cd, Pb, and Zn were at relatively high level, with average concentrations of 15.56, 419.4, and 933.4mg·kg-1 respectively, indicating the soil was heavily polluted. The average concentrations of Hg and As were 0.13 and 37.3mg·kg-1, suggesting moderate soil pollution. The average concentrations of Cu, Ni, and Cr were lower than Yunnan soil background values. The multivariate analysis suggested that the sources of Cd, Pb, Zn, Hg, and As were similar and came mainly from smelting activities in the mining area. The sources of Cu, Ni, and Cr were similar and can be attributed to natural sources. The comprehensive potential ecological risk index was 2294.8, which suggested a high potential ecological risk. In general, the farmland soils in the research area were polluted seriously by the mining and industrial activities.

Ecotoxicological bioassays of sediment leachates in a river bed flanked by decommissioned pesticide plants in Nantong City, East China.

Traditionally, the toxicity of river contaminants is analyzed chemically or physically through river bed sediments. The biotoxicity of polluted sediment leachates has not caught our attention. This study aims to overcome this deficiency through a battery of biotests which were conducted to monitor comprehensive toxicity of sediment leachates for the Yaogang River in East Jiangsu Province of China, which is in close proximity to former pesticide plants. The general physical and chemical parameters of major pollutants were analyzed from river bed sediments collected at five strategic locations. The ecotoxicity analyses undertaken include overall fish (adult zebrafish) acute toxicity, luminescent bacteria (Vibrio fischeri) bioassay, and zebrafish embryo toxicity assay. Compared with the control group, sediment leachates increased the lethality, inhibited the embryos hatching and induced development abnormalities of zebrafish embryos, and inhibited the luminescence of V. fischeri. The results show that sediment leachates may assume various toxic effects, depending on the test organism. This diverse toxicity to aquatic organisms reflects their different sensitivity to sediment leachates. It is found clearly that V. fischeri was the organism which was characterized by the highest sensitivity to the sediment leachates. The complicated toxicity of leachates was not caused by one single factor but by multiple pollutants together. This indicates the need of estimations of sediment leachate not only taking into account chemical detection but also of applying the biotests to the problem. Thus, multigroup bioassays are necessary to realistically evaluate river ecological risks imposed by leachates.

Adsorptive Removal and Adsorption Kinetics of Fluoroquinolone by Nano-Hydroxyapatite.

Various kinds of antibiotics, especially fluoroquinolone antibiotics (FQs) have been widely used for the therapy of infectious diseases in human and livestock. For their poorly absorbed by living organisms, large-scale misuse or abuse of FQs will foster drug resistance among pathogenic bacteria, as well as a variety of environmental problems when they were released in the environment. In this work, the adsorption properties of two FQs, namely norfloxacin (NOR) and ciprofloxacin (CIP), by nano-hydroxyapatite (n-HAP) were studied by batch adsorption experiments. The adsorption curves of FQs by n-HAP were simulated by Langmuir and Freundlich isotherms. The results shown that NOR and CIP can be adsorbed effectively by the adsorbent of n-HAP, and the adsorption capacity of FQs increase with increasing dosage of n-HAP. The optimum dosage of n-HAP for FQs removal was 20 g · L(-1), in which the removal efficiencies is 51.6% and 47.3%, and an adsorption equilibrium time is 20 min. The maximum removal efficiency occurred when pH is 6 for both FQs. The adsorption isotherm of FQs fits well for both Langmuir and Freundlich equations. The adsorption of both FQs by n-HAP follows second-order kinetics.