浅析郭堡水库灌区进行节水工程改造的必要性

介绍了郭堡水库灌区的自然环境、社会经济状况和灌区现状,对供水所面临问题以及改造后的效益进行了分析,阐述了对郭堡水库灌区进行节水改造的必要性。

Numerical simulations of water flow and contaminants transport near mining wastes disposed in a fractured rock mass

A numerical tool, called Hydro-Geosphere, was used to simulate unsaturated water flow and contaminants migration around an open pit filled with mining wastes. Numerical simulations had been carried out to assess the influence of various factors on water flow and solute transport in and around the surface openings including recharge, properties of the waste material and presence of fractures in the surrounding rock mass. The effect of the regional hydraulic gradient was also investigated. The analyses were conducted by simulating various 2D cases using experimentally obtained material properties and controlled boundary conditions. The effects of the hydrogeological properties of the filling material(i.e., water retention curve and hydraulic conductivity function), fracture network characteristics and conductivity of the joints were assessed. The results illustrate that fractures control water flow and contaminants transport around the waste disposal area. A fracture network can desaturate the system and improve the regional gradient effect.

Field-Scale Contaminant Transport Through Soils:Current Understanding and Open Questions

Agro-chemical transport processes at different scales are discussed and relevant opening questions areidentified by literature review to make some suggestions concerning the improvement of research methods forfield scale solute transport by aid of evaluation of existing models, and examining transport behaviors of solutein vadose zones on different scales. The results indicate that present research progress and understanding onfield scale solute transport have not yet been enough to guarantee the use of our models for the management offield solute movement. Much more research work needs to be done, particularly, in aspects of high resolutionof spatial structures relevant to the hydraulic and transport properties, explicit numerical simulation of actualstructure on field scale and field measurement corroborated with model development.

A Study of Transport and Impact Strength of Fukushima Nuclear Pollutants in the North Pacific Surface

Based on the statistics of surface drifter data of 1979-2011 and the simulation of nuclear pollutant particulate move- merits simulated using high quality ocean reanalysis surface current dataset, the transport pathways and impact strength of Fuku-shima nuclear pollutants in the North Pacific have been estimated. The particulates are used to increase the sampling size and en- hance the representativeness of statistical results. The trajectories of the drifters and particulates are first examined to identify typical drifting pathways. The results show that there are three types of transport paths for nuclear pollutants at the surface： 1） most pollutant particles move eastward and are carried by the Kuroshio and Kuroshio-extension currents and reach the east side of the North Pacific after about 3.2-3.9 years; 2） some particles travel with the subtropical circulation branch and reach the east coast of China after about 1.6 years according to one drifter trajectory and about 3.6 years according to particulate trajectories; 3） a little of them travel with local, small scale circulations and reach the east coast of China after about 1.3-1.8 years. Based on the par-tieulates, the impact strength of nuclear pollutants at these time scales can be estimated according to the temporal variations of relative concentration combined with the radioactive decay rate. For example, Cesium-137, carried by the strong North Pacific current, mainly accumulates in the eastern North Pacific and its impact strength is 4% of the initial level at the originating Fuku- shima area after 4 years. Due to local eddies, Cesium-137 in the western North Pacific is 1% of the initial pollutant level after 1.5 years and continuously increases to 3% after 4 years. The vertical movement of radioactive pollutants is not taken into account in the present study, and the estimation accuracy would be improved by considering three-dimensional flows.

Inputs of organochlorine insecticides to Xiamen coastal waters

This paper quantifies organochlorine insecticides （OC1） inputs in the Jiulong River and shows the large use in the agricultural activities and analyses specifically the status of soil, fruit and vegetable contamination by these persistent pollutants in some locations of Xiamen region. From this purpose, soil samples collected from Jiulong agricultural catchment have been analyzed for 18 selected OCI using gas chromatography electron capture detection and to identify the factors that may control the distribution and persistence of organochlorines in the area. The main insecticides found in soil samples were Aldrin, Dieldrin, Endosulfan I1, Endrin aldehyde, Endosulfan sulphate and Methoxychlor. The total organochlorines detected in soil samples ranged from 3.14 to 10.35 ng/g soil. The highest values of OC1 were significantly detected in the orange trees＇ leaves, which range from 1203 to 2681 ng/g soil showing recent uses of these agrochemicals. Their distribution in vegetable samples were also monitored and indicating that the concentration ranged from 3.236 to 7.188 ng/g. The contamination of Jiulong River estuary by organochlorine pesticides has been then widely justified by soil runoffs from these agricultural areas. The results therefore, provide important information on the current contamination status and point to the need for urgent actions to stop the use of persistent agrochemicals. The necessity of implementing systematic monitoring of insecticide contamination is emphasized.