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91.
The concentrations of ammonium NH4+, nitrate NO3-, and nitrite NO2- ions were recorded along with ammonia (NH(3)) emission from a fertilized rice field located in the Kwangju province in South Korea over a period of 4 months (June to October 2006). The highest magnitude of NH(3) flux was 20,754 microg m(-2) h(-1), while the average flux value over the entire sampling period was 2,395 microg m(-2) h(-1). The highest ionic concentrations were 1.67, 0.44, and 0.71 ppm for NH4+, NO3-, and NO2- ions, respectively. Possible effects of soil pH on NH(3) fluxes were detected, as they concurrently exhibited a gradual and periodic change during the sampling period. Positive correlations existed between concentrations of NH4+ and NO2- ions and the soil pH. Positive correlations also existed between NH(3) emission flux and ambient (and water) temperatures. Results indicated that fertilizer application to rice can lead to significant emission of NH(3) along with NH4+ and NO3- ions. 相似文献
92.
Jeong Kyungjun Hong Jiyeon Lee Yongjin Yang Jiyeon Lim Youngwook Shin Dongchun Kim Changsoo 《Environmental science and pollution research international》2021,28(28):37506-37519
Environmental Science and Pollution Research - Preschool children aged 3–6 years are vulnerable to exposed to particulate matter (“PM10” and “PM2.5”). It is required... 相似文献
93.
Shahi Nirmal Kumar Maeng Minsoo Kim Donghyun Lee Taehoon Dockko Seok 《Environmental science and pollution research international》2021,28(30):40598-40607
Environmental Science and Pollution Research - Dissolved air flotation (DAF) is a widely used treatment process in drinking water and wastewater treatment plants despite high energy cost associated... 相似文献
94.
A bias in clear-sky conditions that will be involved in estimating particulate matter(PM)concentration from aerosol optical depth(AOD) was examined using PM_(10) from two Aerosol Robotic Network sites in Korea. The study periods were between 2004 and 2007 at Anmyon and between 2003 and 2011 at Gosan, when both PM_(10) and AOD were available. Mean PM_(10) when AOD was available(PM AOD) was higher than that from all PM_(10)data(PM all) by 5.1 and9.9 μg/m~3 at Anmyon and Gosan, which accounted for 11% and 26% of PM all, respectively.Because of a difference between mean PM_(10) under daytime clear-sky conditions(PM clear)and PM AOD, the variations in ΔPM_(10), the difference of PM all from PM clear rather than from PM AOD, were investigated. Although monthly variations in ΔPM_(10)at the two sites were different, they were positively correlated to those in ΔT, similarly defined as ΔPM_(10)except for temperature, at both sites. ΔPM_(10)at Anmyon decreased to a negative value in January due to an influence of the Siberian continental high-pressure system while ΔPM_(10)at Gosan was high in winter due to an effect of photochemical production at higher temperatures than at Anmyon. 相似文献
95.
畜禽养殖场空气中可培养抗生素耐药菌污染特点研究 总被引:1,自引:0,他引:1
畜禽养殖场被认为是空气环境中耐药基因和致病菌的重要来源.本研究对北京地区22个畜禽养殖场逸散细菌、四环素和红霉素耐药菌气溶胶的浓度进行检测,对其粒径分布和动力学粒径进行分析.结果表明,所调查的3种生物气溶胶(细菌、四环素耐药菌和红霉素耐药菌),在猪舍内浓度最高,牛舍内最低.蛋鸡舍内两种抗生素耐药菌气溶胶的浓度均低于肉鸡.本研究在蛋鸡和肉鸡舍外空气中检测到了四环素和红霉素耐药菌,所占丰度分别为8.81%、15.89%和23.19%、36.53%.不同养殖场舍内外细菌、四环素耐药菌和红霉素耐药菌气溶胶浓度的粒径分布特点存在差异.动力学粒径研究结果显示,4种动物舍内的四环素和红霉素耐药菌气溶胶主要沉降在人体的咽喉和支气管.本研究结果将为评价养殖场生物气溶胶对周边空气环境污染及人类健康造成的危害提供基础数据. 相似文献
96.
97.
Xin Wang Parick Y. Kwon Caleb Sturtevant Dave Kim Jeff Lantrip 《Journal of Manufacturing Processes》2013,15(1):127-135
This study aimed to investigate the wear of certain coated drills when drilling carbon fiber reinforced composites (CFRP). Three different drills were used in the drilling experiments: uncoated, diamond coated and AlTiN coated carbide (WC–Co) drills. The tool wear in CFRP machining was quite different from that in conventional metal machining. The primary wear type was a dulling or blunting of the cutting edge, which has been referred to as edge rounding wear or edge recession. In this paper, a hypothesis has been developed to explain the edge rounding wear in CFRP machining. Due to the fracture-based chip formation of CFRP, there is lack of the work material stagnation zone in front of the cutting edge, which normally prevents the edge wear in metal machining. Series of wear lead to rapid dulling of the cutting edge. The resistance to edge rounding wear on the coated as well as uncoated drills has been investigated. The diamond coating significantly reduces the edge rounding wear. However, AlTiN coated drills showed no visible improvement over the uncoated carbide drill, despite of their high hardness, thus not protecting the drill. The wear mechanisms of the uncoated carbide drill and coatings are discussed. It is believed that the 2-body and 3-body abrasive wear fail to explain the observed tool wear in CFRP drilling. However, the wear of the coatings and uncoated carbide substrate from tribo-meter tests correlated well with the tool wear in the CFRP drilling. Therefore, the tribo-meter test can be used to screen the prospective tool materials before carrying drilling experiment. 相似文献
98.
对闸北区空气自动监测站2009年SO2、NO2、PM10的浓度和气象参数变化特征进行研究,可吸入颗粒物的时间变化特征表明,总体上呈现冬春季高、夏秋季低;PM10与降水量、相对湿度、温度呈现一定的负相关性,但与风速的相关性随季节不同而不同,与气压略呈正相关性。对典型日和灰霾日PM10、SO2、NO2以及相应气象因子的特征进行了分析比较。 相似文献
99.
Gyu-Cheol Lee Weon-Hwa Jheong Gyoo Seung Jung Sung-Ae Oh Min-jeong Kim Ok-Jae Rhee Sujeong Park Chan Hee Lee 《Food and environmental virology》2012,4(3):115-123
RT-PCR, nucleotide sequencing, and phylogenetic analysis were performed for genotyping and molecular characterization of noroviruses isolated from Korean groundwater. Among 160 samples collected from 80 sites between 2008 and 2010, 14 samples (8.7?%) from 12 sites were positive for noroviruses (NoVs). The percentages of NoV-positive samples in 2008, 2009, and 2010 were 22.2, 3.2, and 0?%, respectively, representing a yearly decrease. GII-positive samples (n?=?9, 5.6?%) outnumbered GI-positive samples (n?=?5, 3.1?%). The genotypes of the GI NoVs were GI.2, GI.5, and GI.6, and the genotypes of the GII NoVs were all GII.4. One sample, HM623465, was very similar to CUK-3 and CBNU2 and two GII.4 sequences isolated from the stool of Korean gastroenteritis patients. A BLASTN search revealed several nucleotide sequences highly similar to those of NoVs isolated in this study. The original isolation sources for these similar NoVs were mostly stool (n?=?731, 80.0?%) and groundwater (n?=?135, 14.8?%), and all the countries from which they were isolated were almost in Asia (96.0?%); specifically, China (n?=?192, 21.0?%), Japan (n?=?383, 41.9?%), Korea (n?=?296, 32.4?%), and other Asian countries (n?=?6, 0.7?%). These results suggest that Korean groundwater might be contaminated with NoVs from the stool of infected patients and that these NoVs in turn cause new cases of gastroenteritis through a typical fecal-oral route with region-specific circulation. Therefore, it is important to properly treat sewage, which may include waterborne viruses and manage point sources in groundwater for national health and sanitation. In addition, continuous molecular surveillance remains important for understanding circulating NoVs. 相似文献
100.