Risk assessment of shallow groundwater contamination under irrigation and fertilization conditions     

Xiaolin Zhang  Mei Sun  Neitian Wang  Zailin Huo  Guanhua Huang 《Environmental Earth Sciences》2016,75(7):603

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Case Comparing Study of Downstream Circulation Development during Typhoon Extratropical Transition     

Chen Hua  Huo Ye 《地球科学进展》2016,31(4):409-421

The interaction between extratropical transition process and the mid-latitude jet system stimulates the downstream development. In this paper, three typhoon cases were selected to study their downstream development mechanism through the analysis of the eddy kinetic energy budget and the idealized simulations. The results of Chen’s work to the Pacific region were examined. The results were consistent with the results of Chen’s Atlantic hurricane Case. ET downstream at the upper levels generated first eddies, and the disturbances triggered the low level eddy development. Then the upper and the lower coupled and formed a deep cyclone system throughout the whole troposphere. The ageostrophic geopotential flux promoted the formation and development of the downstream ridge from the typhoon. Vertical ageostrophic geopotential flux transferred energy from upper downward that convergence happened in lower, which stimulated the lower-level cyclone development. Simulation results showed that, in the process of ET, TC outflow transported low potential vorticity to mid-latitude jet, which enhanced the PV gradient and the baroclinic. Then, it is inspired the Rossby wave in the jet and propagated downstream. The formation of downstream ridge-trough couple and development of the further wave was the spread to the downstream through the Rossby wave.  相似文献   

Characteristics of dissolved organic nitrogen (DON) in the surface water of Beijing Olympic Forest Park   总被引：1，自引：0，他引：1  

Shouliang Huo  Honglei Yu  Beidou Xi  Fengyu Zan  Chaowei Zhu  Jingtian Zhang 《Environmental Earth Sciences》2014,71(9):4021-4028

The characteristics of dissolved organic nitrogen (DON) in surface water from Beijing Olympic Forest Park (BOFP) were investigated in this study. Nanofiltration (NF) pretreatment procedure using two NF membranes (NF90 and NF270) was applied to increase the accuracy and precision of DON measurements in surface water samples with high dissolved inorganic nitrogen/total dissolved nitrogen (DIN/TDN) ratios. Compared to NF90, NF270 showed better performance in lowering the DIN/TDN ratio and retaining DOC in both the synthetic water and raw water samples. DON concentrations ranged from 0.01 to 0.83 mg N L^?1 in water samples collected over four different months and showed a seasonal variation. The DON increased in summer due to the higher activity of decomposers on recent litterfall or because of a higher production of biomass in the surface water body. The molecular weight (MW) fractions of <3 kDa accounted for more than 50 % of the total DOC concentration and the fractions of <3 kDa contributed to more than 48 % of the total DON concentration. It could be concluded that most of the DON present in surface water of BOFP was composed of small molecules, which were mainly composed of monomers such as amino acids and urea, readily available for the uptake by phytoplankton and heterotrophic bacteria.  相似文献   

The influences of land-use changes on the absorbed nitrogen and phosphorus loadings in the drainage basin of Lake Chaohu,China   总被引：1，自引：0，他引：1  

Tiantian Jiang  Shouliang Huo  Beidou Xi  Jing Su  Haobo Hou  Hong Yu  Xiang Li 《Environmental Earth Sciences》2014,71(9):4165-4176

The influences of land-use changes on the absorbed nitrogen and phosphorus loadings in the drainage basin of Lake Chaohu were investigated in this study. Based on the principle of universal soil loss equation, a model was developed for estimating the annual mean soil erosion amount from 1989 to 2008 in Chaohu basin. Applying the GIS and soil data, the absorbed nitrogen and phosphorus loadings were stimulated and quantified for three-time stage (1989–1995, 1996–2000, 2001–2008). Furthermore, the influences of historical land-use changes on the absorbed nitrogen and phosphorus loadings were assessed. The results indicated that the absorbed nitrogen and phosphorus loadings of drainage basin have an obvious spatial difference in the three-time stage because of the different characteristics of climate and geology. Temporally, the absorbed nitrogen and phosphorus loadings in the second stage (1996–2000) are less than the one in the first (1989–1995) and third stage (2001–2008), and the load of third stage is the largest, which was mainly impacted by rainfall and land-use change. Forest and grass can act as a source for the load of absorbed nitrogen or absorbed phosphorus. The paddy land and residential land in these areas act as sinks or transformation zones as expected. Other factors such as slope and geology also play important roles in the transport of nutrients and sediments to streams.  相似文献   

Status and challenges of water pollution problems in China: learning from the European experience     

Yun Zhou  Soon-Thiam Khu  Beidou Xi  Jing Su  Fanghua Hao  Jieyun Wu  Shouliang Huo 《Environmental Earth Sciences》2014,72(4):1243-1254

This paper provides a review of the water environment problems faced in China and a comparison with the European experience in dealing with such issues, with an attempt to emphasize the challenges in China. The paper also summarizes various studies in China to highlight the severity of water pollution problems faced by regulators, polluters and the general public. China’s water situation can be characterized by insufficient quantities of water, uneven distribution of water spatially and temporally, as well as poor water quality. Water pollution in China has spread from point source to non-point source, from fresh water to coastal water, and from surface water to groundwater. From the management and technological experience from EU, including water framework directive, water price system, desalination and groundwater recharge technologies, and from the analysis of water environment problems and management system in two regions, we could come to the conclusion that water price, water market and water tax could be introduced to China for water environment regulations. Moreover, it is necessary to establish a reliable risk assessment system for water quality, human health and ecological safety.  相似文献   

An accelerated direct demodulation method for image reconstruction using spherical data from the hard X-ray modulation telescope     

Zhuo-Xi Huo  Jian-Feng Zhou 《天文和天体物理学研究(英文版)》2013,(8):991-1012

The hard X-ray modulation telescope (HXMT) mission is mainly devoted to performing an all-sky survey at 1 250 keV with both high sensitivity and high spatial resolution. The observed data reduction as well as the image reconstruction for HXMT can be achieved by using the direct demodulation method (DDM). However the original DDM is too computationally expensive for multi-dimensional data with high resolution to be employed for HXMT data. We propose an accelerated direct demodulation method especially adapted for data from HXMT. Simulations are also presented to demonstrate this method.  相似文献