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21.
L. Rutigliano D. Fino G. Saracco V. Specchia P. Spinelli 《Journal of Applied Electrochemistry》2008,38(7):1035-1041
This paper describes the results obtained from an electrokinetic treatment of a real soil polluted by lead acetate. Powdered
soil samples were pressed with a consolidometer till 100 kPa to obtain cylindrical specimens with the same characteristics
as a subsoil. Tests were carried out in a Perspex electrochemical cell where soil specimens were introduced with a hollow
punch. A low intensity direct current was applied in order to remove contaminants, due to electrophoresis and electroosmosis
phenomena. The water flow, conductivity, apparent electroosmotic coefficient, as well as other characteristic parameters,
were measured throughout the test. The water content and degree of pore saturation were estimated at the beginning and end
of the test. The soil slab was divided into four slices and the Pb concentration profile determined. The main factor governing
the extraction of contaminant was found to be the pH in the acidic range. Indeed, under these conditions high removal efficiencies
could be reached. These results could lead to the design of a new electrochemical treatment cell equipped with a cationic
membrane to expand the region of favourable pH within the soil. 相似文献
22.
This paper presents the results of an experimental investigation undertaken to evaluate different purging solutions to enhance the removal of multiple heavy metals, particularly chromium, nickel, and cadmium, from a low buffering clay, specifically kaolin, during electrokinetic remediation. Experiments were conducted on kaolin spiked with Cr(VI), Ni(II), and Cd(II) in concentrations of 1,000, 500, and 250 mg/kg, respectively, which simulate typical electroplating waste contamination. A total of five different tests were performed to investigate the effect of different electrode purging solutions on the electrokinetic remedial efficiency. A constant DC voltage gradient of 1 V/cm was applied for all the tests. The removal of heavy metals from the soil using tap water as the purging solution was very low. When 1 M acetic acid was used as the purging solution in the cathode, the removal of chromium, nickel, and cadmium was increased to 20, 19, and 13%, respectively. Using 0.1 M ethylene diamine tetraacetic acid as the purging solution in the cathode, 83% of the initial Cr was removed; however, the nickel and cadmium removal was very low. A sequentially enhanced electrokinetic remediation approach involving the use of water as a purging solution at both the anode and cathode initially, followed by the use of acetic acid as the cathode purging solution and a NaOH alkaline solution as the anode purging solution was tested. This sequential approach resulted in a maximum removal of chromium, nickel, and cadmium of 68–71, 71–73, and 87–94%, respectively. This study shows that the sequential use of appropriate electrode purging solutions, rather than a single electrode purging solution, is necessary to remediate multiple heavy metals in soils using electrokinetics. 相似文献
23.
Digital Yellow River Model 总被引:2,自引:0,他引:2
Soil erosion is one of the key concerns in land use management for the Loess Plateau of the Yellow River, where serious soil loss is the root cause of environmental and ecological degradation of the basin. In this paper, a physically-based, distributed-parameter, and continuous erosion prediction model at the river basin scale was developed with the aim of assisting in developing better land use management strategies. The framework, the major supporting techniques, and the typical erosion processes are described. The physical processes of sediment yield and transport in the Loess Plateau are divided into three sub-processes, including the runoff and sediment yield on hillslopes, gravitational erosion in gullies, and hyperconcentrated flow routing in channels. For each sub-process, a physically-based simulation model was developed and embedded into the whole model system. The model system was applied to simulate the runoff and sediment yield in several typical years in the coarse sediment source area of the Loess Plateau, and the simulated results were in reasonably good agreement with the measured values. 相似文献
24.
以江苏省南通市为研究区,利用采样点实测数据,借助GRNN神经网络模型并结合3S技术对农田土壤重金属的空间动态分布进行了深入研究。结果表明,GRNN神经网络模型能够智能地学习各个采样点的空间位置与该点各重金属含量之间的映射关系,并能够稳健地对各个空间插值点处的土壤重金属含量进行预测;结果显示南通市农田土壤重金属污染总体较轻,但也存在局部地区的严重污染。在运用GRNN神经网络模型进行空间插值了解重金属空间动态分布的基础上,可以根据污染的状况确定农产品的生产布局和规划。 相似文献
25.
太平溪小流域地处三峡库乎宜昌县西部,距三峡坝5km的长江西陵峡北岸,治理前水土流失严重,大量坡面商沙以沟道推移直接进入三峡库区。 相似文献
26.
An efficient method to monitor changes in soil inorganic N content during crop growth would be a useful means to guide N fertilization
to ensure high yields and low N losses to the environment. In this study, soil apparent electrical conductivity (ECa) measured by the widely used conductivity meter EM38 was tested as an indirect measurement of available N in spring barley
during two cropping seasons at two sites with morainic loam in SE Norway. The experiment was constructed to maximize soil
variation. In spite of the ȁ8noiseȁ9 caused by the soil heterogeneity, concentrations of inorganic N (cNinorg) or NO3-N were most strongly correlated with ECa in both years and at both locations (with one exception). The measurements of ECa reflected well the temporal variation in inorganic N content (Ninorg), and a ranking of the treatments based on ECa fitted very well with a ranking based on Ninorg at the first three sampling times after fertilizing. The best subset of sensor variables (i.e. variables which can be measured
ȁ8on-the-goȁ9 by sensor techniques in the field) described 27–69% (average 47%) of the variation in topsoil cNinorg. When expanding the regression models to include pH as well, the degree of explanation increased significantly. In conclusion,
the method of using ECa appears to be quite robust in terms of detecting relative differences in cNinorg, whereas a determination of absolute levels of cNinorg with the method is unreliable. 相似文献
27.
Nitrous oxide (N2O) is a powerful greenhouse gas. As the UK government is committed to reducing greenhouse gas emissions, it is important to know not only how much of these gases are released but also where and when. Targeted measurements of emissions in relation to crop growth cycles, soil wetness and fertiliser applications were used to derive annual emission rates for specific combinations of soil type, land management and fertiliser practices. These annual emission rates were then spatially scaled to derive regional figures through the development of a Geographic Information System (GIS) based model framework. Digital soil and land use maps at a scale of 1:25000 for two test areas of approximately 200000 ha each (Lothians and the Ayrshire Basin) were overlain with a climate map within the GIS, deriving unique combinations of soil wetness and land use. The calculated annual emission rates (kg N ha–1 yr–1) were then applied to these and multiplied by the total area of each soil/land use type to derive annual emission losses for each area. The annual emission of nitrous oxide from the Lothians was determined as approximately 381000 kg N yr–1, while the emissions from the Ayrshire Basin were predicted to be 794000 kg N yr–1. This indicates the increased emissions associated with both the wetter soils of Ayrshire and the greater extent of grazed pasture systems in this area. Due to the detailed scale of the input data, localised areas with large emissions were identified. Abatement strategies would be concentrated on areas of high emissions that include a change to crops with lower emission potential, reducing fertiliser and manure inputs, reducing grazing intensity and improving soil drainage.Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1024422604493 相似文献
28.
本文叙述过氧化钙的性质,并以实例说明过氧比钙在水产养殖、食品加上、果蔬保鲜。环境保护、农作物栽培、橡胶及化工等奋方面的应用。 相似文献
29.
Engracia Madejón Pilar Burgos Rafael López Francisco Cabrera 《Nutrient Cycling in Agroecosystems》2003,65(3):281-288
Disposal of urban, agricultural and industrial organic residues impliesan increasing problem because of all the economic and environmentalrepercussions involved. One of the most adequate ways of managing this problemis the agricultural use of these wastes as organic amendments. Three organicresidues (AC, olive mill waste water sludge compost; MWC, municipal solid wastecompost; and PS, paper mill sludge) were used in a 3-year field experimentinvolving orange production. The effect of their application on crop productionand on soil quality was investigated. Soil samples (0–20 cm depth)collected 11 months after the last soil amendment were analysed for: pH and EC,Kjeldahl-N, available-P, available-K, total organic carbon, humic substances,dehydrogenase, phosphatase, -glucosidase, urease andbenzoyl-argininamidehydrolysing protease (BAA-protease) activities. Generally, the application of the MWC and PSincreased orange yield when compared to control. Moreover, total organic carbonand humic substances significantly increased in soils treated with all theorganic amendments. Organic fertilisation increased the Kjeldahl-N andavailable-P contents of the soil. The application of the organic residues also causedsignificant increases in dehydrogenase, -glucosidase, urease andBAA-protease activities of the soil. Significant positive correlations (p <0.01) between these enzymatic activities and total organic carbon were foundforall treatments. Significant positive correlation between dehydrogenase, urease,-glucosidase, and BAA-protease and orange yield was also found. However,a clear inhibition of phosphatase activity was observed in soils treated withPS. The results indicate that the repeated application to the soil of moderateamounts of organic amendments has positive effects on the chemical andbiochemical properties of the soil, as well as on the orange yield. 相似文献
30.
Francisco Salmerón-Miranda Birgitta Båth Henrik Eckersten Johannes Forkman Maria Wivstad 《Nutrient Cycling in Agroecosystems》2007,79(2):125-139
The main objective of this field study was to estimate the total plant uptake of soil mineral N in maize (Zea mays L.) and common bean (Phaseolus vulgaris L.) grown in crop rotations under different N content in Nicaragua. Secondary objectives were to estimate the fraction of
the measured soil mineral N content taken up in this way, and to determine how the measured N in plant aboveground parts was
related to the total mineral N uptake. A large variation in N content was obtained by using data from fertilisation experiments.
Plant total N uptake was estimated as the residual N in a mass balance calculation of soil mineral N. Mineral N content in
the top 0–0.3 m soil layer in the field cultivations and in tubes isolated from root uptake, and N content in aboveground
plant parts were measured every 30 days. Estimated plant total uptake of soil mineral N varied considerably (2.5–14 g N m−2 30 day−1) over periods and N treatments. The range of variation was similar for maize and bean. The fraction of the soil mineral N
that was taken up by the plant daily varied more in maize (about 0.03–0.12 day−1) than in bean (about 0.05–0.08 day−1). Our results suggest that monthly changes in N in aboveground plant parts were linearly related to plant total N uptake
during the same period. Aboveground plant N constituted between about 55% and 80% of total uptake of soil mineral N in maize
depending on period within season, whereas for bean it was more constant and smaller (about 40%). 相似文献