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Chen J.,Zhejiang University | Chen J.,Zhejiang Province Key Laboratory of Organic Pollution Process and Control | Liu Y.-M.,Hangzhou Environmental Monitoring Center Station | Zhang J.-Y.,Zhejiang University | Zhang J.-Y.,Zhejiang Province Key Laboratory of Organic Pollution Process and Control
Chinese Journal of Applied Ecology | Year: 2014

Species sensitivity distributions (SSDs) methods in both forward and reverse modes were used to evaluate the ecological risk and determine the contaminant concentration threshold for the protection of aquatic species and ecological quality. In this study, the existing toxicity data of freshwater organisms were fitted to SSD functions to estimate the hazardous concentrations for 5% of the species (HC5) for microcystins, ammonia and nitrite, and the ecological risk of their mixtures. The potentially affected fractions (PAFs) of various concentrations of microcystins, ammonia and nitrite were also calculated. Results showed that microcystins exhibited a higher ecological risk than ammonia and nitrite. The HC5 value for microcystins exposure was 19.22 μg·L-1 whereas the HC5 values for ammonia and nitrite exposure were 6583.94 μg·L-1 and 334.33 μg·L-1, respectively. The sensitivity of freshwater organisms varied with exposed concentrations of microcystins, ammonia and nitrite. Crustaceans were more sensitive than fishes to microcystins, and less sensitive than fishes to nitrite when the concentrations of microcystins and nitrite were below 125.04 μg·L-1 and 2989.40 μg·L-1, respectively, and vice versa when exposed to higher concentrations of microcystins and nitrite. No significant difference was observed for the sensitivities of fishes and crustaceans exposed to ammonia. In studies with selected lakes in China, our results showed that the ecological risk in both Tai and Hongfeng lakes exceeded the permissible HC5 threshold, and the multiple substance potentially affected fractions (msPAFs) of microcystins, ammonia and nitrite were 2.6%-5.6%, indicating that the ecological risk of their mixtures was more threatening than each individual contaminant being investigated. Source


Lv J.,Zhejiang University | Lv J.,Zhejiang Province Key Laboratory of Organic Pollution Process and Control | Zhu L.,Zhejiang University | Zhu L.,Zhejiang Province Key Laboratory of Organic Pollution Process and Control
Journal of Environmental Sciences (China) | Year: 2013

Central ventilation and air conditioner systems are widely utilized nowadays in public places for air exchange and temperature control, which significantly influences the transfer of pollutants between indoors and outdoors. To study the effect of central ventilation and air conditioner systems on the concentration and health risk from airborne pollutants, a spatial and temporal survey was carried out using polycyclic aromatic hydrocarbons (PAHs) as agent pollutants. During the period when the central ventilation system operated without air conditioning (AC-off period), concentrations of 2-4 ring PAHs in the model supermarket were dominated by outdoor levels, due to the good linearity between indoor air and outdoor air (rp > 0.769, p < 0.05), and the slopes (1.2-4.54) indicated that ventilating like the model supermarket increased the potential health risks from low molecular weight PAHs. During the period when the central ventilation and air conditioner systems were working simultaneously (AC-on period), although the total levels of PAHs were increased, the concentrations and percentage of the particulate PAHs indoors declined significantly. The BaP equivalency (BaPeq) concentration indicated that utilization of air conditioning reduced the health risks from PAHs in the model supermarket. © 2013 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Source


Lv J.,Zhejiang University | Lv J.,Zhejiang Province Key Laboratory of Organic Pollution Process and Control | Zhu L.,Zhejiang University | Zhu L.,Zhejiang Province Key Laboratory of Organic Pollution Process and Control
Environmental Technology (United Kingdom) | Year: 2013

A short residence time is a key design parameter for the removal of organic pollutants in catalyst-based indoor air purification systems. In this study, we synthesized a series of TiO2 with different micropore volumes and studied their removal efficiency of indoor carbonyl pollutants at a short residence time. Our results indicated that the superior adsorption capability of TiO2 with micropores improved its performance in the photocatalytic degradation of cyclohexanone, while the photocatalytic removal of the pollutant successfully kept porous TiO2 from becoming saturated. When treated with 1 mg m-3 cyclohexanone at a relatively humidity of 18%, the adsorption amount on microporous TiO2 was 5.4-7.9 times higher than that on P25. Removal efficiency via photocatalysis followed the same order as the adsorption amount: TiO2-5 > TiO2-20 > TiO 2-60 > TiO2-180>P25. The advantage of microporous TiO2 over P25 became more pronounced when the residence time declined from 0.072 to 0.036 s. Moreover, as the concentration of cyclohexanone deceased from 1000 ppb to 500 ppb, removal efficiency by microporous TiO2 increased more rapidly than P25. © 2013 Copyright Taylor and Francis Group, LLC. Source


Lu L.,Zhejiang University | Lu L.,Zhejiang Province Key Laboratory of Organic Pollution Process and Control | Zhu L.,Zhejiang University | Zhu L.,Zhejiang Province Key Laboratory of Organic Pollution Process and Control
Journal of Soils and Sediments | Year: 2012

Purpose: The use of cationic surfactants was proposed to enhance the soil retention of hydrophobic organic contaminants (HOCs). However, due to the complexity of soil composition, the effect of cationic surfactants on the soil sorption of HOCs was limited to a qualitative understanding. To gain further insight into the mechanism of the surfactant and predict its efficiency, a comparative study on the HOCs sorption capacities of the surfactants sorbed on pure typical soil components was investigated. Materials and methods: The sorption of cationic surfactant onto five pure typical soil components and the sorption of polycyclic aromatic hydrocarbons (PAHs) by the sorbed surfactant were conducted using batch equilibration methods. Humic acid (HA) and quartz were chosen as the representatives of organic matter and sand, respectively. Montmorillonite, kaolinite, and illite were chosen as representatives of clay minerals. Results and discussion: The cationic surfactant sorption capacities of different soil components were of great difference, and the PAH sorption capacities of the surfactant sorbed onto different components were also very different. Aside from the clay minerals, HA was a very active adsorbent for the cationic surfactant, and the sorption mechanism included both adsorption and partition-like processes. For each pure soil component and a certain PAH, a proximately piecewise function was found to describe the relationship of surfactant-normalized PAH distribution coefficient Ksf and the sorption amount of the surfactant on solid Qe-DDPB (R > 0.9). As a result, the sorption of PAHs by different soil components with certain surfactant loading can be estimated. Conclusions: The effect of soil organic matter such as HA could not be ignored when predicting the soil sorption of cationic surfactants. The PAH partition capacities of the sorbed surfactant on HA or clay minerals were very different. However, for each pure soil component, the Ksf value was specifically related with the surfactant loading, which provided a possible means of predicting the efficiency of the cationic surfactant in enhancing the sorption of PAHs onto soils. © 2011 Springer-Verlag. Source


Lu L.,Zhejiang University | Lu L.,Zhejiang Province Key Laboratory of Organic Pollution Process and Control | Zhu L.,Zhejiang University | Zhu L.,Zhejiang Province Key Laboratory of Organic Pollution Process and Control
Environmental Science and Pollution Research | Year: 2012

Purpose: Cationic surfactants are common in soils because of their use in daily cosmetic and cleaning products, and their use as a soil amendment for the mitigation and remediation of organic contaminated soils has been proposed. Such surfactant may affect the transfer and fate of organic contaminants in the environment. This study investigated the effect of a cationic surfactant, dodecylpyridinium bromide (DDPB), on the volatilization of polycyclic aromatic hydrocarbons (PAHs) from a paddy soil. Materials and methods: The volatilization of PAHs from moist soil amended with different concentrations of DDPB was tested in an open system. The specific effects of DDPB on the liquid-vapor and solid-vapor equilibriums of PAHs were separately investigated in closed systems by headspace analysis. Results and discussion: DDPB affects both liquid-vapor and solid-vapor processes of PAHs in soil. At DDPB concentrations below the critical micelle concentration (CMC), movement of PAHs from the bulk solution to the gas-liquid interface appeared to be facilitated by interaction between PAHs and the surfactant monomers adsorbed at the gas-liquid interface, promoting the volatilization of PAHs from solution. However, when DDPB was greater than the CMC, volatilization was inhibited due to the solubilization of PAHs by micelles. On the other hand, the formation of sorbed surfactant significantly inhibited the solid-vapor volatilization of PAHs. Conclusions: The overall effect of the two simultaneous effects of DDPB on liquid-vapor and solid-vapor processes was a decreased volatilization loss of PAHs from soil. Inhibition of PAH volatilization was more significant for the soil with a lower moisture content. © 2011 Springer-Verlag. Source

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