Controllable Multimodal Actuation in Fully Printed Ultrathin Micro-Patterned Electrochemical Actuators.

Submillimeter or micrometer scale electrically controlled soft actuators have immense potential in microrobotics, haptics, and biomedical applications. However, the fabrication of miniaturized and micropatterned open-air soft actuators has remained challenging. In this study, we demonstrate the microfabrication of trilayer electrochemical actuators (ECAs) through aerosol jet printing (AJP), a rapid prototyping method with a 10 µm lateral resolution. We make fully printed 1000 × 5000 × 12 µm3 ultrathin ECAs, each of which comprises a Nafion electrolyte layer sandwiched between two poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) electrode layers. The ECAs actuate due to the electric-field-driven migration of hydrated protons. Due to the thinness that gives rise to a low proton transport length and a low flexural rigidity, the printed ECAs can operate under low voltages (∼0.5 V) and have a relatively fast response (∼seconds). We print all the components of an actuator that consists of two individually controlled submillimeter segments and demonstrate its multimodal actuation. The convenience, versatility, rapidity, and low cost of our microfabrication strategy promise future developments in integrating arrays of intricately patterned individually controlled soft microactuators on compact stretchable electronic circuits.

Long-term impact of accidental pollution on the distribution and risks of metals and metalloids in the sediment of the Longjiang River, China.

In January 2012, a serious accident polluted the Longjiang River with high concentrations of cadmium (Cd) and other concomitant metals and metalloids in the water. After emergency treatment (i.e., the addition of coagulants), these metals and metalloids were transferred from the water into the sediment through precipitation of the flocculent materials produced. In this study, the long-term distribution of six metals and metalloids in the sediment of the Longjiang River was investigated and their ecological risks were assessed. Approximately 1 year after the accident (i.e., late 2012), the average Cd content in the sediment of the affected sites decreased to 25.6 ± 19.5 mg/kg, which was 8 times higher than that of 3.16 ± 3.18 mg/kg in the upstream reference sites. In 2016 and 2017, the average Cd content in the sediment of the affected sites further decreased to 4.91 ± 2.23 and 6.27 ± 4.27 mg/kg, respectively. Compared with late 2012, the amounts of Zn, Pb, and Cu obviously decreased in 2016 and 2017, whereas there were no obvious differences in the As and Hg amounts during 3 years considered. Among metals and metalloids, the average contribution of Cd to the potential ecological risk index (RI) was 90%, 69%, and 70% in the affected areas in 2012, 2016, and 2017, respectively, suggesting that Cd was the most important factor affecting the ecological risk of metals in the Longjiang River. It should be noted that the average contribution of Hg to RI in the affected areas increased from 8% in 2012 to 25% and 23% in 2016 and 2017, respectively. The sequence of contribution of six elements was Cd > Hg > As>Pb > Cu ≈ Zn. A high ecological risk of metals and metalloids was found in the sediments of two reservoirs, probably owing to the barrier effect of the dam. This study will be useful for the environmental management of rivers affected by accidental pollution of metals and metalloids.

[Distribution and Bioaccumulation Characteristics of Cadmium in Fish Species from the Longjiang River in the Guangxi Autonomous Region].

Emergent cadmium pollution can cause water quality deterioration in rivers, which destroys the aquatic eco-environment and poses threats to human health. Fish species in these aquatic systems are prone to such pollution incidents and act as important indicators of the pollution level. Because cadmium enters the systematic circulation of fish and is non-biodegradable, the investigation of cadmium accumulation in fish bodies provides insights into the detrimental effects of cadmium pollution on the aquatic biological system. This research aims to validate the eco-environmental risks associated with emergent cadmium pollution incidents based on the investigation of the different tissues and organs of diverse fish species. The investigation was conducted six times along the Longjiang River using sampling methods during which all fish species were also classified and analyzed based on the water layer they reside in and their feeding habits. The results show that the cadmium concentration in the fish tissues is significantly higher in the former three investigations compared with that of the latter three analyses. For herbivorous, carnivorous, and omnivorous fish species, the cadmium concentration of their different tissues and organs follows the order:kidney > liver > gut > gill > egg > scale ≈ muscle. The cadmium concentration in the kidney is significantly higher (P<0.05) than that in any other organs of the fish species. This agrees with the fact that the kidney intensively metabolizes and accumulates heavy metals. The cadmium concentration in the same tissues or organs of the fish species living in different water layers follows the trend:demersal fish species > middle lower-layer species > middle upper-layer species. The sequence of the cadmium bioaccumulation factors in the muscles of different fish species is omnivore > carnivorous > herbivorous, that is, 8.32, 6.33, and 5.15, respectively, while the bioaccumulation factors in the muscles of the fish species in different water layers decrease in the following sequence:demersal fish species (8.18) > middle bottom-layer fish species (7.70) > middle upper-layer fish species (4.99). These experimental results indicate the biomagnification effects in heavy metal-polluted aquatic environments, where the bioaccumulation of heavy metals by fish is related to both the overall pollution level and local residential environment.

Seasonal occurrence, removal and risk assessment of 10 pharmaceuticals in 2 sewage treatment plants of Guangdong, China.

A long-term investigation, which covered 10 sampling campaigns over 3 years, was performed to evaluate the occurrence, removal and risk of 10 pharmaceuticals in 2 full-scale sewage treatment plants (STPs) in Guangdong, South China. Target pharmaceuticals except for clofibrate and ibuprofen were detected in every sample, with mean concentrations of 12.5-685.6 and 7.9-130.3 ng/L in the influent and effluent, respectively. Salicylic acid was the most abundant compound in both the influents and effluents in the two STPs. For most pharmaceuticals, the seasonal variation in the influent showed the highest concentrations in January and lowest concentrations in July due to their consumption and rainfall. Ibuprofen and fenoprofen presented high removal rates (>90%) and some of the targets such as gemfibrozil, mefenamic acid, tolfenamic acid and diclofenac were detectable with significantly higher mass loads in effluents than in influents. Studies of the five efficiently eliminated pharmaceuticals show that the primary treatment and secondary treatment contributed to most pharmaceutical removal, the anoxic tank made a negligible contribution to their elimination. According to the results produced from the calculation of the risk quotient, only diclofenac might pose a risk to the aquatic environment.

A Reliable Method to Determine Monomethylmercury and Monoethylmercury Simultaneously in Aqueous Samples by GC-CVAFS After Distillation.

A reliable method for simultaneous determination of monomethylmercury (MeHg) and monoethylmercury (EtHg) in water by gas chromatography with cold vapor atomic fluorescence spectrometry was developed and validated. The experimental conditions, including derivatisation pH, distillation, and complexing agents, were optimized in detail. The absolute detection limits (3σ) were 0.007 ng/L as Hg for MeHg and 0.004 ng/L as Hg for EtHg. The relative standard deviation values (n = 6) for 0.1 ng/L of MeHg and EtHg were 2.7 and 2.1%, 1.0 ng/L of MeHg and EtHg were 6.0 and 6.9%, 4.4 ng/L of MeHg and EtHg were 2.8 and 2.7%, respectively. In addition, five different water samples were analyzed, including river water (RW), effluent wastewater (EW), seawater (SW), industrial wastewater (IW), underground water (UW), and the spiked recoveries of MeHg, were all greater than 85%, whereas EtHg was 86.0% in RW, 83.0% in EW, 87.0% in UW, 82.6% in SW, and 80% in IW. Formation of artefact MeHg and EtHg was studied during distillation. The level of artefact MeHg formed by methylation of Hg(II) during distillation varies from ~ 0.002 to 0.009% for river water and from ~ 0.002 to 0.004% for effluent wastewater, ethylation of Hg(II) was not observed. The method was validated for a variety of water sources with Hg(II) concentrations under 440 ng/L.

Association of PAHs and BTEX exposure with lung function and respiratory symptoms among a nonoccupational population near the coal chemical industry in Northern China.

Emissions (particularly aromatic compounds) from coal industries and biomass fuels combustion lead to high health risks for neighboring residents. To investigate the association of polycyclic aromatic hydrocarbons (PAHs) and benzene, toluene, ethylbenzene and 1,2-dimethylbenzene (BTEX) exposure with lung function and respiratory symptoms among adults and children near the coal-chemical industry in Northern China, adults and children from a county dotted with coal chemical industry were chosen as subjects for investigation (investigated area, IR). The control group consisted of adults and children from an agricultural county (control area, CR). The environmental and urinary PAH and BTEX levels of adults and children were determined by isotope dilution liquid chromatography coupled with tandem mass spectrometry. The Mann-Whitney U test and multivariate linear regression models were used to analyze the relationship between pollutant exposure and the respiratory system. The results showed that in an ambient environment, levels of PAHs and BTEX in the IR were significantly higher than those in the CR. Particularly, the concentration profiles for air samples were IR > CR and indoor > outdoor. Both for adults and children, the geometric (GM) concentrations of urinary PAHs and BTEX from the IR were significantly higher than those measured in the CR. Additionally, the urinary PAH exposure level profiles of smokers were higher than those of nonsmokers, indicating that indoor air and smoking were both important nonoccupational exposure sources. The decline of the forced expiratory in the first second (FEV1, %) and the forced expiratory middle flow rate (FEF25%) in children were associated with increasing urinary PAH metabolite levels (p < 0.05). The increase in urinary 1-OHN, 3-OHPhe, 4-OHPhe and 1-OHP levels could be linked to a decrease in FEV1 (r = -0.179, p < 0.05) and FEF25% with the coefficient of -0.166, -0.201 and -0.175 (p < 0.05), respectively. Medical examinations and lung function tests indicated that residents in the IR had higher occurrences of chest inflammation or declining lung function than residents in the CR. Moreover, exposure to PAHs and BTEX could decrease child lung function, though decreased lung function was not observed in adults. Both urinary monitoring and lung function data showed that children were more sensitive to PAH and BTEX exposure than adults.

Distribution and ecological risk assessment of cadmium in water and sediment in Longjiang River, China: Implication on water quality management after pollution accident.

In early January 2012, the Longjiang River was subjected to a serious cadmium (Cd) pollution accident, which led to negatively environmental and social impacts. A series of measures of emergency treatment were subsequently taken to reduce water Cd level. However, little information was available about the change of Cd level in environmental matrices and long-term effect of this pollution accident to aquatic ecosystem. Thus, this study investigated the distribution of Cd in water and sediment of this river for two years since pollution accident, as well as assessed its ecological risk to aquatic ecosystem of Longjiang River. The results showed that it was efficient for taking emergency treatment measures to decrease water Cd concentration to below the threshold value of national drinking water quality standard of China. There was high risk (HQ > 1) to aquatic ecosystem in some of reaches between February and July 2012, but low or no risk (HQ < 1) between December 2012 to December 2013. Cd concentration in sediment in polluted reaches increased after pollution accident and emergency treatments in 2012, but decreased in 2013. During flood period, the sediment containing high concentration of Cd in Longjiang River was migrated to downstream Liujiang River. Cd content in sediment was reduced to background level after two years of the pollution accident occurrence. The study provides basic information about Cd levels in different media after pollution accident, which is helpful in evaluating the effectiveness of emergency treatments and the variation of ecological risk, as well as in conducting water management and conservation.

[Eutrophication and Characteristics of Cyanobacteria Bloom in the Summer in Guishi Reservoir].

Large-scale cyanobacteria bloom occurred in the summer of 2014 in the Guishi Reservoir that is an important drinking water source for Hezhou City. The dynamic change regularity, external pollution sources, and the phytoplankton community characteristics during the bloom were investigated to evaluate the eutrophication in the reservoir and to present effective prevention and control measures. The results showed that nitrogen and phosphorus concentrations increased year by year; water quality on some sites has been out of class Ⅱ of national water quality standards; and the main pollution source was the agricultural non-point sources. Phytoplankton cell density was in the range of 8.60×106-5.36×108 cells·L-1 and chlorophyll a concentrations reached 74.48 µg·L-1 during the bloom. The dominant species was Microcystis wesenbergii whose density reached 5.36×108 cells·L-1. The cell density decreased over time and concentrated on the surface and at the depth of 2 m underwater. The total phytoplankton cell density was strongly correlated to total phosphorus, total nitrogen, nitrate nitrogen, and the permanganate index, and was inversely correlated to transparency. The water in the Guishi Reservoir was not polluted by microcystic toxins. Moreover, Guishi Reservoir is in a meso-eutrophic state; therefore, the prevention and control of the cyanobacteria bloom should focus on weather conditions and on reducing the input of nitrogen and phosphorus to keep the nutrient levels low.

[Accumulation Characteristics and Health Risk Assessment of Heavy Metals in Wild Fish Species from Diaojiang River, Guangxi].

To explore the accumulation characteristics and health risk assessment of heavy metals in wild fish species, the concentrations of heavy metals (Pb, Cd, Cr, As and Hg) in the muscle samples of eight wild fish species collected from Diaojiang River, Guangxi were analyzed. The degree of pollution, food safety and health risk of heavy metals in wild fish species were evaluated using the average pollution index and the target hazard quotient methods. The results showed that the concentrations of Pb, Cd, Cr, As and Hg in wild fish species ranged from 0.041 to 1.160, 0.0001 to 0.066, 0.173 to 0.789, 0.010 to 2.420 and 0.0007 to 0.077mg·kg-1, respectively. The concentrations of Pb and As in wild fish species exceeded the limit values of the Maximum Levels of Contaminants in Foods (GB 2762-2012), and the over-standard rates were 5.06% and 64.56% respectively. The concentrations of Cd, Cr and Hg did not exceed the standard. The average pollution index results showed that Acheilognathus tonkinensis and Acheilognathus barbatus were seriously polluted by heavy metals. The Oreochromis niloticus were moderately polluted. The Siniperca kneri Garman, Carassius auratus, Pseudohemiculter dispar, Ctenopharyngodon idellus, Hemiculter leucisculus were slightly polluted. Higher bioaccumulation factors of Pb, Cr and Hg were found in wild fish species from Diaojiang River. The concentrations of heavy metals in carnivorous fish and omnivorous fish were higher than those in herbivorous fish. Potential health risk assessment showed that the total target hazard quotients (TTHQ) of Acheilognathus tonkinensis and Acheilognathus barbatus were higher than 1. It indicated that the local residents posed higher human health risk due to the long-term consumption of Acheilognathus tonkinensis and Acheilognathus barbatus. Among all the TTHQ in wild fish species (except Pseudohemiculter dispar and Hemiculter leucisculus), the contribution rate of As was the highest, and the average contribution rate reached 76.63%, which indicated that As was the main risk factor.

Airborne PCDD/Fs in two e-waste recycling regions after stricter environmental regulations.

Since the 2010s, the authorities of Guangdong province and local governments have enhanced law enforcement and environmental regulations to abolish open burning, acid washing, and other uncontrolled e-waste recycling activities. In this study, ambient air and indoor dust near different kinds of e-waste recycling processes were collected in Guiyu and Qingyuan to investigate the pollution status of particles and polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) after stricter environmental regulations. PM2.5 and PCDD/Fs both showed significantly reduced levels in the two regions compared with the documented data. The congener distribution and principal component analysis results also confirmed the significant differences between the current PCDD/Fs pollution characterizations and the historical ones. The estimated total intake doses via air inhalation and dust ingestion of children in the recycling region of Guiyu ranged from 10 to 32pgTEQ/(kg•day), which far exceeded the tolerable daily intake (TDI) limit (1-4pgTEQ/(kg•day). Although the measurements showed a significant reduction of the release of PCDD/Fs, the pollution status was still considered severe in Guiyu town after stricter regulations were implemented.

Sources, atmospheric transport and deposition mechanism of organochlorine pesticides in soils of the Tibetan Plateau.

Because of mountain cold-trapping, the soil in the Tibetan Plateau may be an important global sink of organochlorine pesticides (OCPs). However, there are limited data on OCPs in the soils of the Tibetan Plateau. In addition, the atmospheric transport and deposition mechanisms of OCPs also need to be further studied. In this study, the sampling area covered most regions of the Tibetan Plateau. The detection frequencies of ΣChlordane (sum of trans-chlordane, cis-chlordane and oxychlordane), HCB, ΣNonachlor (sum of trans- and cis-nonachlor), DDTs, ΣEndo (sum of endosulfan-I, endosulfan-II and endosulfate), aldrin, HCHs, ΣHeptachlor (sum of heptachlor and heptachlor epoxide), mirex and dieldrin were 100%, 98.3%, 96.6%, 94.8%, 89.7%, 87.9%, 62.1%, 55.2%, 32.8% and 6.9%, respectively. DDTs (with arithmetic mean values of 1050ngkg-1 dw) and HCHs (393ngkg-1) were the principal OCPs in cultivated soils, whereas ΣEndo (192ngkg-1) and ΣChlordane (152ngkg-1) were the principal OCPs in non-cultivated soils. Local use of DDTs, dicofol and HCHs may be an important source of OCP accumulation in the soil of the Tibetan Plateau. Aldrin and endosulfan are considered to be good indicators for studying atmospheric transport and deposition of OCPs from South Asia and Southeast Asia. Two zones with high OCP levels were found in the southeast and northwest of the Tibetan Plateau. The zones have dissimilar pollution sources of OCPs and are influenced by different factors that affect their precipitation scavenging efficiency. The amount of precipitation was the dominant factor in the southeast, whereas large differences in temperature and wind speed were the dominant factors in the northwest.

Variational Characteristics and Implications of Gaseous Elemental Mercury for Three Continuous Typhoons in China.

Coupling air pollutants with particular meteorological conditions can induce air pollution episodes. To our knowledge, how typhoons influence mercury (Hg) as an extreme weather phenomena has not been reported. Gaseous elemental Hg (GEM) was measured during a time period (from September 16, 2011 to October 9, 2011) that included three typhoons (Haitang, Nesat, and Nalgae) at the Wuzhishan National Atmospheric Background Station. The GEM concentration during these typhoons ranged from 1.81 to 4.73 ng/m(3) (2.97 ± 0.58 ng/m(3)), 1.27 to 4.42 ng/m(3) (2.69 ± 0.83 ng/m(3)), and 1.43 to 2.99 ng/m(3) (2.47 ± 0.32 ng/m(3)), which was higher than for the non-typhoon period (1.14-2.93 ng/m(3), 1.61 ± 0.52 ng/m(3)). Simultaneously, the three typhoon periods exhibited a significant positive correlation between the GEM concentration and wind speed. These results differ from the common belief that lower pollutant concentrations will occur due to a typhoon accelerating pollutant diffusion. Changes in the wind direction and long range pollutant transport from the Chinese mainland can reasonably account for this abnormality. There was a significantly positive correlation between the GEM and SO2, NO x , CO, and O3 levels during the three typhoons periods, which indicates they came from the same sources or areas. A backward trajectory analysis and the concentration weighted field at our monitoring site indicated that clean air masses mainly came from Southeast Asia or the southeast and northeast sea surfaces during non-typhoon periods, while polluted air masses came from the Chinese mainland during the three typhoon periods. The results implied that the increased GEM concentrations in the Wuzhi Mountain were caused by the long-range atmospheric transport of Hg from the Chinese mainland during the typhoon periods. The combustion of coal may be the main emission sources.

Residual veterinary antibiotics in pig excreta after oral administration of sulfonamides.

Sulfonamides (SAs) are applied widely as feed additives in the farming of livestock and poultry. It can lead to the excretion of large amounts of SAs in manure and result in persistent environmental pollution. We evaluated the fate of four SAs, sulfamerazine (SM1), sulfachloropyridazine (SCP), sulfadimoxine (SDM') and sulfaquinoxaline (SQ), from oral administration to excretion in urine and feces in pigs. The four SAs were added to homemade feed to make them reach the required concentration gradient, which were 0, 50 and 100 mg/kg (low, normal and high concentrations, respectively). In different treatments, excretions of the four SAs were 35.68-86.88 %. With regard to total excretion, the order was SQ > SCP > SM1 > SDM' for all treatments. The concentration of SAs in the feed had significant effects on the amount of the four SAs excreted every day. The concentration of SAs in feces and in the urine for different treatments was 15.03-26.55 and 14.54-69.22 %, respectively. In each treatment, excretions of SCP, SDM' and SQ in feces were lower than that in urine. The four SAs remained longer in urine than in feces. Excretions in urine and feces were lower if SAs were administered orally rather than by injection.

[Nitrogen Release Performance of Sediments in Drainage Pipeline].

The effects of soil and water ratio, pH, temperature and rotation on the nitrogen transformation of sediment in drainage pipeline were investigated in this study. The experimental results for the four impact factors indicated that ammonia nitrogen was the main existing form for nitrogen release from the sediment to the overlying water, the concentration of ammonia nitrogen was uptrend, reaching the maximum in four to six days, and it went down till to the end of experiments. While the variation trend of nitrate nitrogen concentration was opposite to that of ammonia nitrogen. The factor of pH influenced most in the release of ammonia nitrogen among the four factors, then was the disturbance, and the temperature had a minimal impact. The release of ammonia nitrogen followed the descending order of pH 6.3 > pH 8.0 > pH 9.6, and the maximum concentrations were 54.0, 30.9 and 26.7 mg x L(-1) respectively. The higher soil and water ratio and the longer agitation time under the same agitation speed were, the higher ammonia nitrogen concentration was obtained. An increase in temperature promoted the conversion of ammonia nitrogen to the nitrate nitrogen, and speeded up the decrease of total nitrogen in the overlying water.

[Phytoplankton community structure and eutrophication risk assessment of Beijiang River].

To study the distribution of phytoplankton and water quality of Beijiang River, the community structure of phytoplankton was investigated and analyzed in wet and dry seasons. The results showed that a total of 74 species belonging to six phyla, 29 family and 48 genera of phytoplankton were identified, including 58 species of five phyla, 23 family and 41 genera in wet season and 59 species of six phyla, 26 family and 40 genera in dry season. Phytoplankton community structure in Beijiang River was represented by Bacillariophyta, Chlorophyta and Cyanophyta. Bacillariophyta dominanted the phytoplankton, and the dominant species were Aulacoseira granulate, Fragilaria virescens, Surirella biseriata, Nitzschia amphibia, Navicula simplex, Cyclotella meneghiniana, Synedra ulna, Gomphonema angustatum and Cymbella tumida. There was little difference in phytoplankton density between both seasons with the mean values being 3.54 x 10(5) and 4.87 x 10(5) cells L(-1) in dry and wet seasons, respectively. Based on the RDA results, DO, permanganate index, nitrogen and phosphorus were the important environmental factors affecting the distribution of phytoplankton in Beijiang River. The water quality of Beijiang River was classified as oligo-mesotrophic level even if this river was subjected to nitrogen and phosphorus pollution mainly from agricultural non-point source.

Characterization and distribution of heavy metals, polybrominated diphenyl ethers and perfluoroalkyl substances in surface sediment from the Dayan River, South China.

In this study, surface sediment samples were collected from 11 sites in the Dayan River near an electronic waste site in Qingyuan. Heavy metals, polychlorinated biphenyls (PBDEs) and perfluoroalkyl substances (PFASs) were detected. The concentrations of Cu, Zn, Pb and Cd ranged from 12.1 to 641, 47.1 to 891, 39.2 to 641, 0.12 to 2.07 mg/kg dw, respectively. Total PBDEs ranged between 0.052 and 126.64 ng/g dw. BDE-47 and BDE-99 were the predominant PBDEs. The concentrations of PFASs in sediments ranged between 0.01 and 3.72 ng/g dw. The perfluorooctane sulfonate was predominantly PFASs. The strong positive correlations among Cu, Zn, perfluorooctanoic acid and PBDEs indicate that these contaminants were associated with each other and may share a common anthropogenic source in the sediments of the Dayan River.

Assessment of exposure to heavy metals and health risks among residents near Tonglushan mine in Hubei, China.

Heavy metal contamination due to mining activity is a global major concern because of its potential health risks to local inhabitants. In the present study, we investigated the levels of Cd, Cu, Pb and As in soil, crop, well water and fish samples collected from the vicinity of the Tonglushan mine in Hubei, China, and evaluated potential health risks among local residents. Results indicate that soils near the mine were heavily contaminated with Cd (2.59 mg kg(-1)), Cu (386 mg kg(-1)), Pb (120 mg kg(-1)) and As (35.4 mg kg(-1)), and exceeded the soil quality standard values of Cd and Cu contamination. The concentrations of Cd, Cu, Pb and As in crop samples grown in mine-affected soils were significantly higher than those of the reference soils. The concentrations of Cd and As in most vegetables grown in mine-affected soils exceeded the maximum allowable level (MAL). The Cd, Pb and As concentration in rice grain collected from mine-affected soils were 2.95, 1.85 and 2.07-fold higher than the MAL, respectively. The concentrations of Cd and As in fish muscle from the mine-affected area were above national MAL in 61% and 34% of analyzed samples, respectively. All measured heavy metals except Pb were significantly greater in well water in the mine-affected area than those in the reference areas. The average estimated daily intakes of Cd and As were beyond the provisional tolerable daily intake, respectively. The intake of rice was identified as a major contributor (⩾72%) to the estimated daily intake among the residents.

Biomass fuels and coke plants are important sources of human exposure to polycyclic aromatic hydrocarbons, benzene and toluene.

Large amounts of carcinogenic polycyclic aromatic hydrocarbons (PAHs), benzene and toluene (BT) might be emitted from incomplete combustion reactions in both coal tar factories and biomass fuels in rural China. The health effects arising from exposure to PAHs and BT are a concern for residents of rural areas close to coal tar plants. To assess the environmental risk and major exposure sources, 100 coke plant workers and 25 farmers in Qujing, China were recruited. The levels of 10 mono-hydroxylated PAHs (OH-PAHs), four BT metabolites and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in the urine collected from the subjects were measured. The 8-OHdG levels in the urine were determined to evaluate the oxidative DNA damage induced by the PAHs and BT. The results showed that the levels of the OH-PAHs, particularly those of 1-hydroxynathalene and 1-hydroxypyrene, in the farmers were 1-7 times higher than those in the workers. The concentrations of the BT metabolites were comparable between the workers and farmers. Although the exact work location within a coke oven plant might affect the levels of the OH-PAHs, one-way ANOVA revealed no significant differences for either the OH-PAHs levels or the BT concentrations among the three groups working at different work sites. The geometric mean concentration (9.17 µg/g creatinine) of 8-OHdG was significantly higher in the farmers than in the plant workers (6.27 µg/g creatinine). The levels of 8-OHdG did not correlate with the total concentrations of OH-PAHs and the total levels of BT metabolites. Incompletely combusted biomass fuels might be the major exposure source, contributing more PAHs and BT to the local residents of Qujing. The estimated daily intakes (EDIs) of naphthalene and fluorene for all of the workers and most of the farmers were below the reference doses (RfDs) recommended by the U.S. Environmental Protection Agency (EPA), except for the pyrene levels in two farmers. However, the EDIs of benzene in the workers and local farmers ranged from 590 to 7239 µg/day, and these levels were 2- to 30-fold higher than the RfDs recommended by the EPA. Biomass fuel combustion and industrial activities related to coal tar were the major sources of the PAH and BT exposure in the local residents. Using biomass fuels for household cooking and heating explains the higher exposure levels observed in the farmers relative to the workers at the nearby coal tar-related industrial facility.

[Selection of electrochemical anodic materials for PFOA degradation and its mechanism].

Perfluorooctanoate (PFOA) is environmentally stable and endocrine-disrupting. It was resistant to conventional biodegradation and advanced oxidation processes. Electrochemical oxidation method was adopted to degrade PFOA. The anodes, including BDD, Pt, Ti, Ti/RuO2, Ti/RuO2-IrO2, Ti/In2O3, Ti/SnO2-Sb2O5,-IrO2, Ti/SnO2-Sb2O5,-RhO2, Ti/SnO2-Sb2O5, Ti/ SnO2-Sb2O5,-CeO2 and Ti/SnO2-Sb2O5-Bi2O3, were selected as the candidate materials. The oxygen evolution potential (OEP) were determined by linear sweep voltammetry (LSV). The degradation ratios and the defluorination ratios were used to evaluate the oxidation ability of anodic materials. Ultrasonic electrochemical oxidation indirectly demonstrated that direct electron transfer was the initial step for PFOA decomposition. The anodes of Ti/SnO,-Sb20 ,-Bi2,03, Ti/SnO-Sb ,O,-CeO,, Ti/SnO2-Sb20, and BDD effectively degraded PFOA, and the decomposition ratios were 89. 8% , 89. 8% , 93. 3% and 98. 0% , respectively. The removal ratios of PFOA on Ti/ SnO2-Sb2O5,-RhO2, Ti/SnO2-Sb2O5-IrO2, and Ti/In2O3 anodes were low, and the values were 2. 1%, 2.3% , 12. 5% and 3.1%, respectively. However, Ti, Ti/RuO2 and Ti/RuO2-IrO2, had no effect on PFOA. PFOA molecule transferred electrons to the anode, decarboxylated, and followed the CF2, unzipping cycle. The intermediate products detected were C6F13 COO- , C5F11COO-, C4F9COO- and C3F7,COO-.

Fenton Oxidation Kinetics and Intermediates of Nonylphenol Ethoxylates.

Removal of nonylphenol ethoxylates (NPEOs) in aqueous solution by Fenton oxidation process was studied in a laboratory-scale batch reactor. Operating parameters, including initial pH temperature, hydrogen peroxide, and ferrous ion dosage, were thoroughly investigated. Maximum NPEOs reduction of 84% was achieved within 6 min, under an initial pH of 3.0, 25°C, an H2O2 dosage of 9.74×10-3 M, and a molar ratio of [H2O2]/[Fe2+] of 3. A modified pseudo-first-order kinetic model was found to well represent experimental results. Correlations of reaction rate constants and operational parameters were established based on experimental data. Results indicated that the Fenton oxidation rate and removal efficiency were more dependent on the dosage of H2O2 than Fe2+, and the apparent activation energy (ΔE) was 17.5 kJ/mol. High-performance liquid chromatography and gas chromatograph mass spectrometer analytical results indicated degradation of NPEOs obtained within the first 2 min stepwise occurred by ethoxyl (EO) unit shortening. Long-chain NPEOs mixture demonstrated a higher degradation rate than shorter-chain ones. Nonylphenol (NP), short-chain NPEOs, and NP carboxyethoxylates were identified as the primary intermediates, which were mostly further degraded.