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421.
Ozone concentrations, flux and potential effect on yield during wheat growth in the Northwest-Shandong Plain of China 总被引:1,自引:0,他引:1
Ozone (O3) concentration and flux (Fo) were measured using the eddy covariance technique over a wheat field in the Northwest-Shandong Plain of China. The O3-induced wheat yield loss was estimated by utilizing O3 exposure-response models. The results showed that: (1) During the growing season (7 March to 7 June, 2012), the minimum (16.1 ppbV) and maximum (53.3 ppbV) mean O3 concentrations occurred at approximately 6:30 and 16:00, respectively. The mean and maximum of all measured O3 concentrations were 31.3 and 128.4 ppbV, respectively. The variation of O3 concentration was mainly affected by solar radiation and temperature. (2) The mean diurnal variation of deposition velocity (Vd) can be divided into four phases, and the maximum occurred at noon (12:00). Averaged Vd during daytime (6:00–18:00) and nighttime (18:00–6:00) were 0.42 and 0.14 cm/sec, respectively. The maximum of measured Vd was about 1.5 cm/sec. The magnitude of Vd was influenced by the wheat growing stage, and its variation was significantly correlated with both global radiation and friction velocity. (3) The maximum mean Fo appeared at 14:00, and the maximum measured Fo was − 33.5 nmol/(m2·sec). Averaged Fo during daytime and nighttime were − 6.9 and − 1.5 nmol/(m2·sec), respectively. (4) Using O3 exposure-response functions obtained from the USA, Europe, and China, the O3-induced wheat yield reduction in the district was estimated as 12.9% on average (5.5%–23.3%). Large uncertainties were related to the statistical methods and environmental conditions involved in deriving the exposure-response functions. 相似文献
422.
The responses of soil ammonia-oxidizing archaea(AOA) and ammonia-oxidizing bacteria(AOB) to mercury(Hg) stress were investigated through a short-term incubation experiment.Treated with four different concentrations of Hg(CK,Hg25,Hg50,and Hg100,denoting 0,25,50,and 100 mg Hg/kg dry soil,respectively),samples were harvested after 3,7,and 28 day incubation.Results showed that the soil potential nitrification rate(PNR) was significantly inhibited by Hg stress during the incubation.However,lower abundances of AOA(the highest in CK: 9.20 × 10~7 copies/g dry soil; the lowest in Hg50: 2.68 × 10~7 copies/g dry soil) and AOB(the highest in CK: 2.68 × 10~7 copies/g dry soil; the lowest in Hg50:7.49 × 10~6 copies/g dry soil) were observed only at day 28 of incubation(P 0.05).Moreover,only the community structure of soil AOB obviously shifted under Hg stress as seen through DGGE profiles,which revealed that 2–3 distinct AOB bands emerged in the Hg treatments at day 28.In summary,soil PNR might be a very useful parameter to assess acute Hg stress on soil ecosystems,and the community structure of soil AOB might be a realistic biological indicator for the assessment of heavy metal stress on soil ecosystems in the future. 相似文献
423.
The aim of the study was to prepare a porous sound-absorbing material using steel slag and fly ash as the main raw material, with coal powder and sodium silicate used as a pore former and binder respectively. The influence of the experimental conditions such as the ratio of fly ash, sintering temperature, sintering time, and porosity regulation on the performance of the porous sound-absorbing material was investigated. The results showed that the specimens prepared by this method had high sound absorption performance and good mechanical properties, and the noise reduction coefficient and compressive strength could reach 0.50 and 6.5 MPa, respectively. The compressive strength increased when the dosage of fly ash and sintering temperature were raised. The noise reduction coefficient decreased with increasing ratio of fly ash and reducing pore former, and first increased and then decreased with the increase of sintering temperature and time. The optimum preparation conditions for the porous sound-absorbing material were a proportion of fly ash of 50% (wt.%), percentage of coal powder of 30% (wt.%), sintering temperature of 1130°C, and sintering time of 6.0 hr, which were determined by analyzing the properties of the sound-absorbing material. 相似文献
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427.
This paper examines the temporal change and spatial variation of population pressure on the ecological environment in China. We have collected sufficient data from the statistical yearbooks of 31 provincial administrative areas in 1990, 1995, 2000, 2005, and 2010. Using a geographic information system (GIS) and relevant models, we analyzed the trend of the population pressure on ecological environment and the change of the gravity center of ecological environment quality. We conclude that: (1) generally, population pressure on the ecological environment in China was becoming higher during 1990–2010, especially in some areas where the population and environment were in serious imbalance and the ecological environment experienced severe pollution; (2) during a certain period, population pressure on the ecological environment was becoming lower in some areas, but the ecological environment was getting worse; (3) the areas with super-high population pressure on the ecological environment were Beijing, Tianjin, and Shanghai; (4) the gravity center of population pressure on the ecological environment and the center of ecological environment quality move differently during the study time period, but the general trend was similar – both of them were moving from west to east. Based on the analysis, this paper also provides some policy suggestions on the control of ecological environment quality. 相似文献
428.
计算静态应力降与动态应力降之比Y值,根据Y值的大小初步判定地震类型,是震后趋势判定的一种新方法,对震后趋势快速判定有一定意义。通过计算我省历年有影响地震的Y值,发现2005年以来黑龙江省及其周边地区中强地震静态应力降与动态应力降之比(Y值)在0.3~0.6之间,总体来说Y值较大,其地震类型以孤立型地震为主,吉林省前郭县地震Y值为0.37,与我省其他中强地震相比,Y值相对较低,初步判定为震群型地震。 相似文献
429.
The effects of sediment-laden waters on irrigated lands along the lower Yellow River in China 总被引:1,自引:0,他引:1
Mingzhou Q Jackson RH Zhongjin Y Jackson MW Bo S 《Journal of environmental management》2007,85(4):858-865
Expansion of irrigation in the Yellow River (Huang He in Chinese) Basin of China is a major accomplishment of the post-revolutionary period in China. Irrigation reliance on the Yellow River was anticipated to not only supply greater reliability of water for crops, but also to improve the productivity of aeolian, saline and alkali soils because of the high sediment loads in the river. Irrigation expansion also was a significant factor in affecting human modification of the landscape ecosystem in the lower reaches of the Yellow River. Based on field investigation and sampling of the amount and distribution of used suspended sediment load in irrigated areas, this paper analyzes the impact of the suspended sediment on soil texture, fertility and salinity and the consequences to the landscape ecosystem. Results indicate that soil quality has indeed been improved through irrigation and related deposition of sediment, but some local problems created by long periods of irrigation should not be ignored in the future. 相似文献
430.
Polycyclic aromatic hydrocarbons(PAHs), as persistent toxic substances(PTS), have been widely monitored in coastal environment, including seawater and sediment. However, scientific monitoring methods, like ecological risk assessment and integrated biomarker response, still need massive researches to verify their availabilities. This study was performed in March, May, August and October of 2018 at eight sites, Yellow River estuary(S1), Guangli Port(S2), Xiaying(S3), Laizhou(S4), Inner Bay(S5), Ou... 相似文献