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961.
Wenming Dong Jiamin Wan Tetsu K. Tokunag Benjamin Gilbert Kenneth H. Williams 《环境科学学报(英文版)》2017,29(7):24-32
In order to understand the transport and humification processes of dissolved organic matter(DOM) within sediments of a semi-arid floodplain at Rifle,Colorado,fluorescence excitation–emission matrix(EEM) spectroscopy,humification index(HIX) and specific UV absorbance(SUVA) at 254 nm were applied for characterizing depth and seasonal variations of DOM composition.Results revealed that late spring snowmelt leached relatively fresh DOM from plant residue and soil organic matter down into the deeper vadose zone(VZ).More humified DOM is preferentially adsorbed by upper VZ sediments,while non-or lesshumified DOM was transported into the deeper VZ.Interestingly,DOM at all depths undergoes rapid biological humification process evidenced by the products of microbial by-product-like(i.e.,tyrosine-like and tryptophan-like) matter in late spring and early summer,particularly in the deeper VZ,resulting in more humified DOM(e.g.,fulvic-acid-like and humic-acid-like substances) at the end of year.This indicates that DOM transport is dominated by spring snowmelt,and DOM humification is controlled by microbial degradation,with seasonal variations.It is expected that these relatively simple spectroscopic measurements(e.g.,EEM spectroscopy,HIX and SUVA) applied to depth-and temporally-distributed pore-water samples can provide useful insights into transport and humification of DOM in other subsurface environments as well. 相似文献
962.
Daekyun Kim Nuray Ates Sehnaz Sule Kaplan Bekaroglu Meric Selbes Tanju Karanfil 《环境科学学报(英文版)》2017,29(8):155-162
The main objective of this study was to assess the combined use of chlorine dioxide (ClO2) and chlorine (Cl2) on the speciation and kinetics of disinfection by-product (DBP) formation in swimming pools using synthetic pool waters prepared with a body fluid analog (BFA) and/or fresh natural water. At 1:25 (mass ratio) of ClO2 to Cl2, there was no significant reduction in the formation of trihalomethanes (THMs) and haloacetic acids (HAAs) for both BFA solution and natural water compared to the application of Cl2 alone. When the mass ratio of ClO2 to Cl2 increased to 1:1, substantial decreases in both THMs and HAAs were observed in the natural water, while there was almost no change of DBP formations in the BFA solution. Haloacetonitriles and halonitromethanes levels in both water matrices remained similar. In the presence of bromide, the overall DBP formation increased in both BFA solution and natural water. For the DBP formation kinetics, after 72 hr of contact time, very low formation of THMs and HAAs was observed for the use of ClO2 only. Compared to Cl2 control, however, applying the 1:1 mixture of ClO2/Cl2 reduced THMs by > 60% and HAAs by > 50%. Chlorite was maintained below 1.0 mg/L, while the formation of chlorate significantly increased over the reaction time. Finally, in a bench-scale indoor pool experiment, applying ClO2 and Cl2 simultaneously produced less THMs compared to Cl2 control and kept chlorite at < 0.4 mg/L, while HAAs and chlorate accumulated over 4-week operation period. 相似文献
963.
Sungwoon Jung Jaehyun Lim Sangil Kwon Sangwoo Jeon Jeongsoo Kim Jongtae Lee Sunmoon Kim 《环境科学学报(英文版)》2017,29(4):21-32
Emission characterization of particle number as well as particle mass from three diesel passenger cars equipped with diesel particulate filter(DPF), diesel oxidation catalyst(DOC)and exhaust gas recirculation(EGR) under the vehicle driving cycles and regulatory cycle.Total particle number emissions(PNEs) decreased gradually during speed-up of vehicle from 17.3 to 97.3 km/hr. As the average vehicle speed increases, the size-segregated peak of particle number concentration shifts to smaller size ranges of particles. The correlation analysis with various particulate components such as particle number concentration(PNC),ultrafine particle number concentration(UFPNC) and particulate matter(PM) mass was conducted to compare gaseous compounds(CO, CO_2, HC and NOx). The UFPNC and PM were not only emitted highly in Seoul during severe traffic jam conditions, but also have good correlation with hydrocarbons and NOxinfluencing high potential on secondary aerosol generation. The effect of the dilution temperature on total PNC under the New European Driving Cycle(NEDC), was slightly higher than the dilution ratio. In addition, the nuclei mode(DP: ≤ 13 nm) was confirmed to be more sensitive to the dilution temperature rather than other particle size ranges. Comparison with particle composition between vehicle speed cycles and regulatory cycle showed that sulfate was slightly increased at regulatory cycle, while other components were relatively similar. During cold start test, semivolatile nucleation particles were increased due to effect of cold environment. Research on particle formation dependent on dilution conditions of diesel passenger cars under the NEDC is important to verify impact on vehicular traffic and secondary aerosol formation in Seoul. 相似文献
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967.
Soundscapes in recreation settings are becoming an important issue, but there are few studies of the effects of sounds on
recreation experiences, especially crowding perceptions and encounter norms. This study compared effects of six types of sounds
(an airplane, a truck engine, children playing, birds, water, and a control) on perceived crowding (PC) and encounter norms
for hikers. Data were collected from 47 college students through lab experiments using simulated images, with moving hikers
inserted in the original photo taken in the Jungmeori area of Mudeungsan Provincial Park in Korea. Overall, the motor-made
sounds of the airplane and truck engine increased PC and decreased acceptability ratings, and the natural sounds of birds
and water decreased PC and increased acceptability ratings. Ratings of the sound of children playing were similar to those
in the control (i.e., no sound). In addition, as numbers of hikers increased, the overall effects of sounds decreased, and
there were few significant differences in PC or acceptability ratings at the highest encounter levels. Theoretical and methodological
implications are discussed. 相似文献
968.
969.
Edu Inam Supawan Khantotong Kyoung-Woong Kim Bulgan Tumendemberel Sugar Erdenetsetseg Tamir Puntsag 《Environmental geochemistry and health》2011,33(1):57-69
The environmental impacts of Boroo gold mine project in Mongolia was evaluated by chemical characterization of trace element concentrations in water, soils and tailing dam sediment samples. The results showed that concentrations of B, Cd, Ni and Se in the water samples were within the accepted levels of the Mongolia water quality standard (MNS4586: 1998). However, the concentrations of Al, As, Cu, Mn, Fe, Pb, U and Zn were higher than the maximum allowable concentration especially in the monitoring and heap leach wells. The average concentrations of As, Cd, Cu, Ni, Pb and Zn in the tailing dam sediment were 4419, 58.5, 56.0, 4.8, 20.6 and 25.7 mg/kg, respectively. Generally, arsenic and heavy metals in the soil samples were within the acceptable concentrations of the soil standard of Mongolia (MNS 5850: 2008). The chemical characterization of As solid phase in tailing dam sediment showed that the majority of As were found in the residual fraction comprising about 74% of total As. Assessing the potential risk to humans, simple bioavailability extraction test was used to estimate bioavailability of arsenic and heavy metals, and the concentrations extracted from tailing dam sediment were; 288.2 mg/kg As, 7.2 mg/kg Cd, 41.1 mg/kg Cu, 13.5 mg/kg Pb, 4.7 mg/kg Ni and 23.5 mg/kg Zn, respectively. From these results, the Boroo gold mine project has presently not significantly impacted the environment, but there is a high probability that it may act as a source of future contamination. 相似文献
970.
Yong Sik Ok Sang Soo Lee Weon-Tai Jeon Sang-Eun Oh Adel R. A. Usman Deok Hyun Moon 《Environmental geochemistry and health》2011,33(1):31-39
Liming materials have been used to immobilize heavy metals in contaminated soils. However, no studies have evaluated the use of eggshell waste as a source of calcium carbonate (CaCO3) to immobilize both cadmium (Cd) and lead (Pb) in soils. This study was conducted to evaluate the effectiveness of eggshell waste on the immobilization of Cd and Pb and to determine the metal availability following various single extraction techniques. Incubation experiments were conducted by mixing 0–5% powdered eggshell waste and curing the soil (1,246 mg Pb kg?1 soil and 17 mg Cd kg?1 soil) for 30 days. Five extractants, 0.01 M calcium chloride (CaCl2), 1 M CaCl2, 0.1 M hydrochloric acid (HCl), 0.43 M acetic acid (CH3COOH), and 0.05 M ethylendiaminetetraacetic acid (EDTA), were used to determine the extractability of Cd and Pb following treatments with CaCO3 and eggshell waste. Generally, the extractability of Cd and Pb in the soils decreased in response to treatments with CaCO3 and eggshell waste, regardless of extractant. Using CaCl2 extraction, the lowest Cd concentration was achieved upon both CaCO3 and eggshell waste treatments, while the lowest Pb concentration was observed using HCl extraction. The highest amount of immobilized Cd and Pb was extracted by CH3COOH or EDTA in soils treated with CaCO3 and eggshell waste, indicating that remobilization of Cd and Pb may occur under acidic conditions. Based on the findings obtained, eggshell waste can be used as an alternative to CaCO3 for the immobilization of heavy metals in soils. 相似文献