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151.
Cadmium (Cd) distribution and contamination in Chinese paddy soils on national scale 总被引:5,自引:0,他引:5
Xiaojuan Liu Guangjin Tian Dong Jiang Chi Zhang Lingqiang Kong 《Environmental science and pollution research international》2016,23(18):17941-17952
Rice is a staple food by an increasing number of people in China. As more issues have arisen in China due to rice contaminated by cadmium (Cd), Cd contamination in arable soils has become a severe problem. In China, many studies have examined Cd contamination in arable soils on a national scale, but little studies have focused on the distribution of Cd in paddy fields. This study explored the spatial pattern of Cd in paddy soils in China, made a preliminary evaluation of the potential risk, and identified the most critically contaminated regions based on the domestic rough rice trade flow. The results showed that Cd concentrations in paddy soils in China ranged from 0.01 to 5.50 mg/kg, with a median value of 0.23 mg/kg. On average, the highest Cd concentrations were in Hunan (0.73 mg/kg), Guangxi (0.70 mg/kg), and Sichuan (0.46 mg/kg) provinces. Cd concentrations in paddy soils in central and western regions were higher than those in eastern regions, especially the southeastern coastal regions. Of the administrative regions, Cd standard exceedance rate was 33.2 %, and the heavy pollution rate was 8.6 %. Regarding to Cd of paddy soil, soil environmental quality was better in Northeast China Plain than in Yangtze River Basin and southeastern coastal region. Mining activities were the main anthropogenic pollution source of Cd in Chinese paddy soil. Based on rice trade, more of the Chinese population would be exposed to Cd through intake of rice produced in Hunan province. Certain regions that output rice, especially Hunan province, should be given priority in the management and control of Cd contamination in paddy soil. 相似文献
152.
选择我国饮用水水质标准中有相关规定,以及部分用量较大或虽被禁用但仍有残留的农药共25种,对黄浦江水源水以及采用臭氧活性炭-后置砂滤工艺的某水厂工艺段出水中的浓度分布进行了调查,评估了砂滤后置工艺条件下相应农药的实际处理效果。结果表明:原水中有包括莠去津、乐果、六氯苯、敌敌畏、乙草胺、丁草胺、仲丁威和p,p'-DDT的8种农药检出,且总浓度较高达到760 ng/L,其中莠去津和乙草胺含量较高,最高浓度分别达到531 ng/L和277 ng/L;从季节性分布来看,春季总农药浓度最高达760 ng/L,秋季最低为175 ng/L。从工艺去除效果来看,臭氧活性炭砂滤后置工艺对农药的总体去除率为62%~78%,与冬春季相比,夏秋季节的农药的去除率提高约10%左右,这可能与高温期微生物活性较高有关。值得关注的是,砂滤后置工艺与同期常规臭氧活性炭工艺相比农药的总去除率要低10%左右,应结合总体出水水质情况对其进一步评估。 相似文献
153.
154.
Hai-bo Xu Dao-yuan Zhao Yu-jiao Li Pei-ya Liu Chang-xun Dong 《Environmental science and pollution research international》2014,21(7):5132-5140
ortho-Nitrochlorobenzene (o-NCB) in soil poses significant health risks to human because of its persistence and high toxicity. The removal of o-NCB by both zero-valent iron (ZVI) and chemical oxidation (persulfate) was investigated by batch experiments. The o-NCB removal rate increases significantly from 15.1 to 97.3 % with an increase of iron dosage from 0.1 to 1.0 mmol g?1. The o-NCB removal rate increases with the decrease of the initial solution pH, and a removal efficiency of 90.3 % is obtained at an initial pH value of 6.8 in this combined system. It is found that temperature and soil moisture could also increase the o-NCB removal rate. The o-NCB degradation rate increases from 83.9 to 96.2 % and from 41.5 to 82.4 % with an increase of temperature (15 to 35 °C) and soil moisture (0.25 to 1.50 mL g?1), respectively. Compared to the persulfate oxidation system and ZVI system, the persulfate–iron system shows high o-NCB removal capacity. o-NCB removal rates of 41.5 and 62.4 % are obtained in both the persulfate oxidation system and the ZVI system, while the removal rate of o-NCB is 90.3 % in the persulfate–iron system. 相似文献
155.
为有效去除发电厂烟气中产生的NOx,利用介质阻挡放电(DBD)产生低温等离子体并结合催化剂Ag/Al2O3进行烟气脱硝实验,研究了在加入乙烯的条件下,平均负载量、催化温度和装置的布置方式对NOx脱除的影响。结果表明,随着负载的增多,NO脱除率呈现先增大后减小的趋势,5种负载量中最佳为1.76%;随着催化温度的升高,NO脱除率同样呈现先增大后减小的趋势,最佳的催化温度为150℃左右;3种不同布置方式对NO和NOx脱除有明显差别,单独催化剂在NO和NOx的脱除率都比较低;单独介质阻挡放电NO脱除率很高,但是NOx很却很低;而两者结合在NO和NOx都达到了很好的效果。 相似文献
156.
Tree bark as a passive air sampler to indicate atmospheric polybrominated diphenyl ethers (PBDEs) in southeastern China 总被引:1,自引:0,他引:1
Xiaoxu Fu Junxia Wang Xiaoyu Zhou Jingjing Deng Yangcheng Liu Wei Zhang Lili Liu Liang Dong Kuangfei Lin 《Environmental science and pollution research international》2014,21(12):7668-7677
The different barks were sampled to discuss the influence of the tree species, trunk circumference, and bark thickness on the accumulation processes of polybrominated diphenyl ethers (PBDEs) from air into the bark. The results of different PBDE concentrations indicated that barks with a thickness of 0–3 mm collected from weeping willow, Camphor tree, and Masson pine, the trunk circumferences of which were 100 to 150 cm, were better PBDEs passive samplers. Furthermore, tree bark and the corresponding air samples were collected at Anji (AJ), Hangzhou (HZ), Shanghai (SH), and Wenling (WL) to investigate the relationship between the PBDE concentrations in bark and those in air. In addition, the significant correlation (r 2?=?0.906; P?<?0.05) indicated that atmospheric PBDEs were the principle source for the accumulation of PBDEs in the barks. In this study, the log K BA (bark–air partition coefficient) of individual PBDE congeners at the four sites were in the range from 5.69 to 6.79. Finally, the total PBDE concentration in WL was 5 to 20 times higher than in the other three cities. The result indicated that crude household workshops contributed a heavy amount of PBDEs pollution to the environment, which had been verified by the spatial distribution of PBDEs levels in barks collected at Wenling (range, 26.53–1317.68 ng/g dw). The good correlation between the PBDE concentrations in the barks and the air samples and the variations of the PBDE concentrations in tree barks collected from different sites reflected that the bark could be used as a passive sampler to indicate the atmospheric PBDEs. 相似文献
157.
Distribution of antibiotic-resistant bacteria in chicken manure and manure-fertilized vegetables 总被引:3,自引:0,他引:3
Qingxiang Yang Siwei Ren Tianqi Niu Yuhui Guo Shiyue Qi Xinkuan Han Dong Liu Feng Pan 《Environmental science and pollution research international》2014,21(2):1231-1241
Veterinary manure is an important pollution reservoir of antibiotics and antibiotic-resistant bacteria (ARB). However, little is known of the distribution of ARB in plant endophytic bacteria and the number/types of ARB in chicken manure. In this study, 454-pyrosequencing was used to investigate the distribution and composition of ARBs in chicken manure and fertilized vegetables. The prevalence of ARB in the samples of the chicken manure compost recovered from farms on which amoxicillin, kanamycin, gentamicin, and cephalexin were used was 20.91–65.9 % for ARBs and 8.24–20.63 % simultaneously resistant to two or more antibiotics (multiple antibiotic resistant bacteria (MARB)). Antibiotic-resistant endophytic bacteria were widely detected in celery, pakchoi, and cucumber with the highest rate of resistance to cephalexin. The pyrosequencing indicated that the chicken manure dominantly harbored Firmicutes, Bacteroidetes, Synergistetes, and Proteobacteria and that Bacteroidetes was significantly enhanced in farms utilizing antibiotics. In the total cultivable colonies, 62.58–89.43 % ARBs and 95.29 % MARB were clustered in Bacteroidetes with the dominant species (Myroides ordoratimimus and Spningobacterium spp., respectively) related to human clinical opportunistic pathogens. 相似文献
158.
Shipeng Dong Liang Mao Siqiang Luo Lei Zhou Yiping Feng Shixiang Gao 《Environmental science and pollution research international》2014,21(3):2358-2366
Concentrations of aqueous-phase nonylphenol (NP), a well-known endocrine-disrupting chemical, are shown to be reduced effectively via reaction with lignin peroxidase (LiP) or horseradish peroxidase (HRP) and hydrogen peroxide. We systematically assessed their reaction efficiencies at varying conditions, and the results have confirmed that the catalytic performance of LiP toward NP was more efficient than that of HRP under experimental conditions. Mass spectrum analysis demonstrated that polymerization through radical–radical coupling mechanism was the pathway leading to NP transformation. Our molecular modeling with the assistance of ab initio suggested the coupling of NP likely proceeded via covalent bonding between two NP radicals at their unsubstituted carbons in phenolic rings. Data from acute immobilization tests with Daphnia confirm that NP toxicity is effectively eliminated by LiP/HRP-catalyzed NP removal. The findings in this study provide useful information for understanding LiP/HRP-mediated NP reactions, and comparison of enzymatic performance can present their advantages for up-scale applications in water/wastewater treatment. 相似文献
159.
Dong Young Kim Jung Wk Kim 《Journal of the Air & Waste Management Association (1995)》2013,63(3):340-347
ABSTRACT A speciated, hourly, and gridded air pollutants emission modeling system (SHEMS) was developed and applied in predicting hourly nitrogen dioxide (NO2) and ozone (O3) levels in the Seoul Metropolitan Area (SMA). The primary goal of the SHEMS was to produce a systemized emission inventory for air pollutants including ozone precursors for modeling air quality in urban areas. The SHEMS is principally composed of three parts: (1) a pre-processor to process emission factors, activity levels, and spatial and temporal information using a geographical information system; (2) an emission model for each source type; and (3) a post-processor to produce report and input data for air quality models through database modeling. The source categories in SHEMS are point, area, mobile, natural, and other sources such as fugitive emissions. The emission database produced by SHEMS contains 22 inventoried compounds: sulfur dioxide, NO2, carbon monoxide, and 19 speciated volatile organic compounds. To validate SHEMS, the emission data were tested with the Urban Airshed Model to predict NO2 and O3 concentrations in the SMA during selected episode days in 1994. The results turned out to be reliable in describing temporal variation and spatial distribution of those pollutants. 相似文献
160.
为防治冲击地压危害,减小人员伤亡与经济损失,采用数值计算方法建立吸能让位防冲液压支架与围岩协同作用体系模型,计算支架和围岩组合体系在静载和冲击载荷作用下的受力状态.结果表明:静载条件下,受煤层影响巷道右侧拱肩位置应力值与塑性应变相对最大,此处最易发生破坏;吸能装置在静载条件下没有发生压缩变形,表明吸能装置不会影响支架正... 相似文献