Risk assessment of maize drought disaster in southwest China using the Environmental Policy Integrated Climate model   总被引：2，自引：0，他引：2  

Hui-cong Jia  Dong-hua Pan  Jing Li  Wan-chang Zhang  Rasul Ghulam 《山地科学学报》2016,13(3):465-475

The East Asian monsoon has a tremendous impact on agricultural production in China. An assessment of the risk of drought disaster in maize-producing regions is therefore important in ensuring a reduction in such disasters and an increase in food security. A risk assessment model, EPIC(Environmental Policy Integrated Climate) model, for maize drought disasters based on the Erosion Productivity Impact Calculator crop model is proposed for areas with the topographic characteristics of the mountainous karst region in southwest China. This region has one of the highest levels of environmental degradation in China. The results showed that the hazard risk level for the maize zone of southwest China is generally high. Most hazard index values were between 0.4 and 0.5,accounting for 47.32% of total study area. However,the risk level for drought loss was low. Most of the loss rate was 0.1, accounting for 96.24% of the total study area. The three high-risk areas were mainlydistributed in the parallel ridge–valley areas in the east of Sichuan Province, the West Mountain area of Guizhou Province, and the south of Yunnan Province.These results provide a scientific basis and support for the reduction of agricultural drought disasters and an increase in food security in the southwest China maize zone.  相似文献   

Size distributions and source function of sea spray aerosol over the South China Sea     

CHU Yingjia  SHENG Lifang  LIU Qian  ZHAO Dongliang  JIA Nan  KONG Yawen 《中国海洋大学学报(英文版)》2016,15(4):569-576

The number concentrations in the radius range of 0.06 – 5 μm of aerosol particles and meteorological parameters were measured on board during a cruise in the South China Sea from August 25 to October 12, 2012. Effective fluxes in the reference height of 10 m were estimated by steady state dry deposition method based on the observed data, and the influences of different air masses on flux were discussed in this paper. The number size distribution was characterized by a bimodal mode, with the average total number concentration of(1.50 ± 0.76)×10~3 cm~(-3). The two mode radii were 0.099 μm and 0.886 μm, both of which were within the scope of accumulation mode. A typical daily average size distribution was compared with that measured in the Bay of Bengal. In the whole radius range, the number concentrations were in agreement with each other; the modes were more distinct in this study than that abtained in the Bay of Bengal. The size distribution of the fluxes was fitted with the sum of log-normal and power-law distribution. The impact of different air masses was mainly on flux magnitude, rather than the shape of spectral distribution. A semiempirical source function that is applicable in the radius range of 0.06 μmr_(80)0.3 μm with the wind speed varying from 1.00 m s~(-1) to 10.00 m s~(-1) was derived.  相似文献   

An approach to determination of phenolic compounds in seawater using SPME-GC-MS based on SWCNTs coating   总被引：1，自引：0，他引：1  

ZHU Jia  WANG Ying  ZENG Lin 《中国海洋大学学报(英文版)》2016,15(4):655-659

Phenolic compounds have become one kind of the important pollutants of the marine environment. Single-walled Carbon nanotubes, as one-dimensional nano materials, have light weight and perfect hexagonal structure of connections, with many unusual mechanical, chemical and electrical properties. In recent years, with the research of carbon nanotubes and other nano materials, the application prospect is also constantly discussed. In this paper, homemade single-walled carbon nanotubes(SWCNTs) coating was used for establishing an analytical approach to the determination of five kinds of phenolic compounds in seawater using SPME-GC-MS. Optimal conditions: After saturation was conducted with Na Cl, and p H was adjusted to 2.0 with H_2SO_4, the extract was immersed in a water bath at 40 for GC℃-MS determination through 40-min agitating extraction at 500 rmin~(-1) and 3-min desorption at 280℃. The liniearities ranged between 0.01-100 μg L~(-1), and the determination limits ranged between 1.5-10 ngL~(-1). The relative standard deviation(RSD, n = 5) was less than 6.5%. For the phenolic compounds obtained from the spiked recovery test for actual seawater samples, the rates of recovery were 87.5%-101.7%, and the RSDs were less than 8.8%, which met the requirements of determination. Due to its simplicity, high efficiency and low consumption, this approach is suitable for the analysis of trace amounts of phenolic compounds in marine waters.  相似文献   

Distribution of soil nitrogen and its relationship with particle size along the Dan river valley,China     

Jun Zhang  Peng Li  Chunrong Jia  Zhanbin Li  Hui Tang  Yuanyuan Yang 《Environmental Earth Sciences》2016,75(5):406

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Aqueous geochemistry and its influence on the partitioning of arsenic between aquifer sediments and groundwater: a case study in the northwest of the Hetao Basin   总被引：1，自引：0，他引：1  

Ping Ni  Huaming Guo  Yongsheng Cao  Yongfeng Jia  Yuxiao Jiang  Di Zhang 《Environmental Earth Sciences》2016,75(4):356

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Pressure transient analysis of multistage fracturing horizontal wells with finite fracture conductivity in shale gas reservoirs     

Yu Dai  Xinhua Ma  Ailin Jia  Dongbo He  Yunsheng Wei  Cong Xiao 《Environmental Earth Sciences》2016,75(11):940

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Regional runoff variation and its response to climate change and human activities in Northwest China   总被引：1，自引：0，他引：1  

Jia Qin  Yuexia Liu  Yaping Chang  Shiwei Liu  Hongzheng Pu  Jiaxin Zhou 《Environmental Earth Sciences》2016,75(20):1366

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Soil column infiltration tests on biomediated capillary barrier systems for mitigating rainfall-induced landslides     

Sheng Hua Tan  Shi Wei Wong  Du Jia Chin  Min Lee Lee  Ying Hui Ong  Siaw Yah Chong  Azman Kassim 《Environmental Earth Sciences》2018,77(16):589

Rainfall-induced landslide is a common geohazard in tropical and humid regions. Capillary barrier system (CBS) is a popular and widely studied mitigating measure for rainfall-induced landslides. However, several previous studies have shown that the performance of the conventional CBS under intense rainfalls has not been particularly convincing. This paper aims to explore the feasibility and effectiveness of a newly proposed system, known as “biomediated capillary barrier system” (B-CBS) in minimizing water infiltration into soil. A one-dimensional soil column was used to investigate the infiltration characteristics of the proposed system. The results showed that the B-CBS of biomediated residual soil overlying original residual soil (Test IV) could effectively control the infiltration into soil by taking advantage of the less-permeable biomediated soil cover. The B-CBS of biomediated residual soil overlying gravelly sand (Test V) and the three-layered B-CBS of fine sand overlying gravelly sand and biomediated residual soil (Test VI) showed the best performance in terms of minimizing the water infiltration. A suction of about 5 kPa still remained in the soil column after 60 min of infiltration from the ponded water on the soil surface.  相似文献   

Laboratory investigations of inert gas flow behaviors in compact sandstone     

Chaojun Jia  Weiya Xu  Huanling Wang  Wei Wang  Jun Yu  Zhinan Lin 《Environmental Earth Sciences》2018,77(6):245

The seepage evolution behavior of compact rock is significant for the stability and safety of many engineering applications. In this research, both hydrostatic and triaxial compression tests were conducted on compact sandstone using an inert gas, namely argon. A triaxial compression test with a water permeability measurement was carried out to study the difference between the gas permeability and water permeability evolutions during the complete stress–strain process. Based on the experimental data, the hydrostatic stress-dependent gas permeability was discussed firstly. A second-order function was proposed to predict and explain the gas slippage effect. The mechanical properties and crack development of the sandstone samples were discussed to better understand the permeability evolution with crack growth during the complete stress–strain process. The results show that the gas permeability evolution can be divided into five stages according to the different crack growth stages. Then, the permeability changes in the crack closure stress \( \sigma_{\text{cc}} \), crack initiation stress \( \sigma_{\text{ci}} \), crack damage stress \( \sigma_{\text{cd}} \) and peak stress \( \sigma_{\text{p}} \) with confining pressures were analyzed. Finally, we found that the difference between the corrected gas permeability and water permeability can be attributed to the interaction between the water and sandstone grains.  相似文献   

Mechanical behavior and micro-structure of cement kiln dust-stabilized expensive soil     

Su Li Cui  Jia Ding Wang  Xiao Dong Wang  Yan Feng Du  Xue Pan Wang 《Arabian Journal of Geosciences》2018,11(17):521

In this study, the effects of cement kiln dust (CKD) on the swelling properties, strength properties, and microstructures of CKD-stabilized expansive soil were investigated. Samples were prepared and stabilized with different CKD content ratios, ranging from 0 to 18% by dry mass. The results obtained show that the maximum swelling pressures decrease exponentially with increases in CKD content. Both the cohesion and unconfined compressive strength (UCS) increase at ratios below 10% CKD and then decrease slightly, above that ratio. CKD can also improve the strength of saturated, expansive soil. There is no visible change of UCS for soil without CKD when cured, while the UCS of a sample with 10% CKD content after curing for 90 days is higher than that after curing for only 1 day. This indicates that CKD can improve the long-term strength of expansive soil. Finally, microstructure analysis reveals that the addition of CKD reduces the montmorillonite content of expansive soil and decreases its swelling properties. The addition of CKD also changes the pore volume distribution, both the size and amount of macro-pores and micro-pores decrease with increase in CKD content. For saturated samples, the size of macro-pores is obviously reduced, while that of micro-pores is slightly increased for both treated and untreated soils. Hydration and saturation processes make the soil structure become dispersive which results in a lower strength, and adding CKD can restrain this process. The suggested optimal CKD content is between 10 and 14% and with a curing time of more than 27 days.  相似文献