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861.
862.
Coupling of zero valent iron and biobarriers for remediation of
trichloroethylene in groundwater 总被引:1,自引:0,他引:1
This study attempted to construct a three series barrier system to treat high concentrations of trichloroethylene (TCE; 500 mg/L) in
synthetic groundwater. The system consisted of three reactive barriers using iron fillings as an iron-based barrier in the first column,
sugarcane bagasse mixed with anaerobic sludge as an anaerobic barrier in the second column, and a biofilm coated on oxygen carbon
inducer releasing material as an aerobic barrier in the third column. In order to evaluate the extent of removal of TCE and its metabolites
in the aquifer down gradient of the barrier system, a fourth column filled with sand was applied. Residence time of the system was
investigated by a bromide tracer test. The results showed that residence time in the column system of the control set and experimental
set were 23.62 and 29.99 days, respectively. The e ciency of the three series barrier system in removing TCE was approximately
84% in which the removal e ciency of TCE by the iron filling barrier, anaerobic barrier and aerobic barrier were 42%, 16% and 25%,
respectively. cis-Dichloroethylene (cis-DCE), vinyl chloride (VC), ethylene and chloride ions were observed as metabolites following
TCE degradation. The presence of chloride ions in the e uent from the column system indicated the degradation of TCE. However,
cis-DCE and VC were not fully degraded by the proposed barrier system which suggested that another remediation technology after
the barrier treatment such as air sparging and adsorption by activated carbon should be conducted. 相似文献
863.
通过对桉树速生林基地的生态调查及监测,分析得出以前我国桉树速生林普遍存在地力衰退的问题,导致土壤肥力下降及目前桉树人工林地力衰退已经得到根本性的逆转的主要原因。速生林基地种植的桉树林林下植被与林缘、林外植被没有显著不同,特别是与桉树林地块相近的稀疏马尾松林林下植被以及荒坡植被相比,无论从植被覆盖度、植物种类、高度等看都呈现出增高、增多的趋势,而广东雨量丰富,桉树能同绝大部分林下植物共生。 相似文献
864.
865.
Optimizing water quality monitoring networks using continuous longitudinal monitoring data: a case study of Wen-Rui Tang River, Wenzhou, China 总被引:1,自引:0,他引:1
Mei K Zhu Y Liao L Dahlgren R Shang X Zhang M 《Journal of environmental monitoring : JEM》2011,13(10):2755-2762
Identification of representative sampling sites is a critical issue in establishing an effective water quality monitoring program. This is especially important at the urban-agriculture interface where water quality conditions can change rapidly over short distances. The objective of this research was to optimize the spatial allocation of discrete monitoring sites for synoptic water quality monitoring through analysis of continuous longitudinal monitoring data collected by attaching a water quality sonde and GPS to a boat. Sampling was conducted six times from March to October 2009 along a 6.5 km segment of the Wen-Rui Tang River in eastern China that represented an urban-agricultural interface. When travelling at a velocity of ~2.4 km h(-1), this resulted in water quality measurements at ~20 m interval. Ammonia nitrogen (NH(4)(+)-N), electrical conductivity (EC), dissolved oxygen (DO), and turbidity data were collected and analyzed using Cluster Analysis (CA) to identify optimal locations for establishment of long-term monitoring sites. The analysis identified two distinct water quality segments for NH(4)(+)-N and EC and three distinct segments for DO and turbidity. According to our research results, the current fixed-location sampling sites should be adjusted to more effectively capture the distinct differences in the spatial distribution of water quality conditions. In addition, this methodology identified river reaches that require more comprehensive study of the factors leading to the changes in water quality within the identified river segment. The study demonstrates that continuous longitudinal monitoring can be a highly effective method for optimizing monitoring site locations for water quality studies. 相似文献
866.
867.
Xiaobin Liao Joshua M. Allen Caroline O. Granger Susan D. Richardson 《环境科学学报(英文版)》2022,34(7):264-275
Halogenated disinfection byproducts (DBPs) are an unintended consequence of drinking water disinfection, and can have significant toxicity. XAD resins are commonly used to extract and enrich trace levels of DBPs for comprehensive, nontarget identification of DBPs and also for in vitro toxicity studies. However, XAD resin recoveries for complete classes of halogenated DBPs have not been evaluated, particularly for low, environmentally relevant levels (ng/L to low µg/L). Thus, it is not known whether levels of DBPs or the toxicity of drinking water might be underestimated. In this study, DAX-8/XAD-2 layered resins were evaluated, considering both adsorption and elution from the resins, for extracting 66 DBPs from water. Results demonstrate that among the 7 classes of DBPs investigated, trihalomethanes (THMs), including iodo-THMs, were the most efficiently adsorbed, with recovery of most THMs ranging from 50%-96%, followed by halonitromethanes (40%-90%). The adsorption ability of XAD resins for haloacetonitriles, haloacetamides, and haloacetaldehydes was highly dependent on the individual species. The adsorption capacity of XAD resins for haloacetic acids was lower (5%-48%), even after adjusting to pH 1 before extraction. Recovery efficiency for most DBPs was comparable with their adsorption, as most were eluted effectively from XAD resins by ethyl acetate. DBP polarity and molecular weight were the two most important factors that determine their recovery. Recovery of trichloromethane, iodoacetic acid, chloro- and iodo-acetonitrile, and chloroacetamide were among the lowest, which could lead to underestimation of toxicity, particularly for iodoacetic acid and iodo-acetonitrile, which are highly toxic. 相似文献
868.
随着中国城市规模迅速扩大、人口急剧增加,给城市水环境造成了巨大压力.由于绝大多数水环境信息是与空间位置关系密不可分的,在使用传统管理信息系统以及数据统计方式处理大量的水环境数据时,并不能很好地利用与呈现空间特征,因此,具有地理空间分析功能的地理信息系统(GIS)逐渐受到重视.然而,目前GIS在城市水环境管理中仍存在需要思考和改善的地方,以形成完整的城市水环境决策系统,提出可用的环境改善建议. 相似文献
869.
镉对人类和动物是一种毒性极强的污染物,由于工业化发展和人类活动范围扩大,导致环境镉污染越来越严重.环境监测站用火焰原子吸收光谱法测定镉,但影响镉准确测定的因素较多.为了优化原子吸收测定镉的仪器参数,利用正交试验法,对原子吸收分析过程中需要设置的原素灯工作电流、燃气流量和燃烧器高度三个主要因素进行无交互作用试验,优化仪器参数:原素灯工作电流4mA、燃气流量1 200 ml/min、燃烧器高度5.0 mm,其中燃气流量影响最显著. 相似文献
870.
Mingqiang Huang Jiahui Zhang Shunyou Cai Yingmin Liao Weixiong Zhao Changjin Hu Xuejun Gu Li Fang Weijun Zhang 《环境科学学报(英文版)》2016,28(9):219-229
Aging of secondary organic aerosol(SOA) particles formed from OH– initiated oxidation of ethylbenzene in the presence of high mass(100–300 μg/m~3) concentrations of(NH_4)_2SO_4seed aerosol was investigated in a home-made smog chamber in this study.The chemical composition of aged ethylbenzene SOA particles was measured using an aerosol laser time-of-flight mass spectrometer(ALTOFMS) coupled with a Fuzzy C-Means(FCM) clustering algorithm.Experimental results showed that nitrophenol,ethyl-nitrophenol,2,4-dinitrophenol,methyl glyoxylic acid,5-ethyl-6-oxo-2,4-hexadienoic acid,2-ethyl-2,4-hexadiendioic acid,2,3-dihydroxy-5-ethyl-6-oxo-4-hexenoic acid,1H-imidazole,hydrated N-glyoxal substituted1H-imidazole,hydrated glyoxal dimer substituted imidazole,1H-imidazole-2-carbaldehyde,N-glyoxal substituted hydrated 1H-imidazole-2-carbaldehyde and high-molecular-weight(HMW) components were the predominant products in the aged particles.Compared to the previous aromatic SOA aging studies,imidazole compounds,which can absorb solar radiation effectively,were newly detected in aged ethylbenzene SOA in the presence of high concentrations of(NH_4)_2SO_4seed aerosol.These findings provide new information for discussing aromatic SOA aging mechanisms. 相似文献