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421.
为研究围垦对滨海滩涂土壤重金属的影响,采用土柱实验模拟淋洗脱盐过程,分析了滨海滩涂不同植被演替带(光滩、互花米草滩、碱蓬滩、芦苇滩)土壤在淋洗脱盐前后重金属(As、Hg、Cd、Cr、Pb、Cu、Zn)含量的变化,评估了围垦可能导致的滩涂重金属流失量。研究表明,淋洗脱盐后,各植被演替带土壤重金属均显著降低,相比而言,Hg、Cr更易淋洗(淋洗率分别为57.2%、49.9%),而Zn不易淋洗(淋洗率18.5%);不同植被演替带土壤重金属淋洗率表现为:光滩互花米草滩碱蓬滩芦苇滩,光滩土壤重金属更易淋洗,而芦苇滩重金属不易淋洗;根据土壤容重、含水率、淋洗率及重金属含量计算重金属流失量发现,不同植被演替带重金属流失量同样表现为:光滩互花米草滩碱蓬滩芦苇滩;除互花米草滩As流失量较高外(19.26 kg·ha-1),其他重金属流失量均表现为光滩最高,光滩围垦可能会造成更多的重金属流失;在仅考虑淋洗脱盐情况下,以江苏省2010~2020年围垦规划270万亩计,仅表层20 cm滩涂土壤,通过围垦即可能导致As、Hg、Cd、Cr、Pb、Cu、Zn流失2 102.5、7.4、421.3、8 587.9、4 376.3、2 404.3 t,由围垦导致的滩涂重金属流失风险值得关注。 相似文献
422.
P. J. Murray D. J. Hatch E. R. Dixon S. Granger C. OPrey R. J. Stevens R. J. Laughlin S. C. Jarvis 《Water, Air, & Soil Pollution: Focus》2004,4(6):45-52
Much work has been done on gaseous emissions and leaching of nitrogenous compounds from whole soil profiles and also from soil surface measurements which are assumed to be mainly due to topsoil activity. In soils with an impervious clay subsoil, the boundary between the topsoil and subsoil may provide an interface for microbial activity, including N transformations. In this study, we investigated movement and transformations of two reactive N species (nitrate and urea) at the subsoil interface using a series of replicate, intact soil blocks, under two contrasting watering regimes. We measured fluxes in both liquid and gaseous phases and demonstrated that nitrate reaching the subsoil interface does not necessarily leach into water systems, but may denitrify immediately and could, therefore, add to atmospheric pollution through N2O production. On the other hand, ammonium reaching the subsoil interface either directly, or after mineralization, appears to be more mobile than expected and has the potential to pollute watercourses. 相似文献
423.
Allah Bakhsh Ramesh S. Kanwar 《Journal of the American Water Resources Association》2005,41(2):333-341
ABSTRACT: Grouping of nitrate‐nitrogen (NO3‐N) leaching losses from agricultural fields into spatial clusters can help determine the cause/effect relationships for their occurrence. This study was designed to investigate the spatial relationships of low, medium, and high NO3‐N leaching losses clusters with soil and landscape attributes using cluster and discriminant analysis and the map overlay capability of a geographical information system (GIS). Field measured data of a six‐year (1993 through 1998) study on NO3‐N leaching losses from 36 experimental fields at the Iowa State University's northeastern research center near Nashua, Iowa, were normalized on an annual basis to compare over the years. The cluster analysis resulted in the formation of three clusters based on the satisfactory evaluation criteria of pseudo‐F statistic, cubic clustering criterion, and R2 values. The discriminant analysis, carried out on the basis of clusters, identified elevation and subsurface drainage as the factors that contributed significantly (p > 0.01) in discriminating among these clusters. The verification of discriminant functions developed on these factors predicted the cluster membership for all the groups with an overall accuracy of 86 percent. The map overlay analyses of GIS showed that spatial occurrence of the clusters transporting high NO3‐N leaching losses was affected by the interaction of soil type and elevation levels. 相似文献
424.
Regional Assessment of Nutrient and Pesticide Leaching in the Vegetable Production Area of Rattaphum Catchment, Thailand 总被引:1,自引:0,他引:1
Regional groundwater vulnerability maps to indicate the impact of leaching of chemicals under different management scenarios
were prepared for the Rattaphum Catchment using several leaching models and GIS techniques. The Attenuation Factor (AF) model
was used to simulate the leaching potential of several pesticides for selected soils in the catchment under different rates
of recharge from irrigation. The LEACHN model was used to simulate the NO3
− leaching potential and LEACHP was used to simulate leaching potential of metolachlor under different management scenarios.
The results showed that only a small number of pesticides have the potential to contaminate the shallow groundwater. However,
the risk of contamination with nutrients is much higher due to the mobility and conservative nature of the NO3
−. The LEACHP results indicated that the intensive use of agrochemicals in the vegetable growing area, especially during the
rainy season when the groundwater is near the surface, increases the risk of pesticide contamination. The results of upscaling
from the farm to the catchment scale using soil maps and GIS techniques under various management scenarios and chemical application
rates showed that the most effective strategy to reduce chemical leaching is by reducing pesticide application rates and optimizing
the application of irrigation water. The identification of potential high risk farms by ranking soils and agricultural practices
could be used to formulate management practices that reduce pesticide contamination of the surface and ground water resources
in the area. 相似文献
425.
以废弃的阴极射线管锥玻璃碱性浸出渣及屏玻璃混合粉末为原料烧制泡沫玻璃。考察了发泡温度、屏玻璃加入量、发泡剂种类、发泡剂加入量、稳泡剂添加量对所制备的泡沫玻璃密度及抗压强度的影响。实验结果表明:在发泡温度800 ℃、屏玻璃加入量50%(w)、稳泡剂硼酸加入量5%(以锥玻璃碱性浸出渣及屏玻璃粉末总质量为基准,下同)、发泡剂SiC加入量15%最佳条件下烧制的泡沫玻璃密度达417 kg/m3,抗压强度达1.09 MPa,可满足建筑用泡沫玻璃的Ⅳ型物理性能指标。本实验烧制的泡沫玻璃的Pb浸出量为1.27 mg/L,Ba浸出量为0.06 mg/L,均满足固体废物的浸出毒性标准。 相似文献
426.
427.
废旧车用载钯催化剂中钯的浸出研究 总被引:5,自引:0,他引:5
针对汽车尾气的污染,汽车排气系统都安装有含铂族金属的汽车催化剂.废旧汽车催化剂已成为铂族金属重要的二次资源.本文采用湿法浸出整体式蜂窝陶瓷汽车催化剂中的铂族金属钯.氧化焙烧废汽车催化剂除去积炭和其他有机物,再磨细过筛100目后烘干.预处理过的废催化剂用还原剂HCOOH溶液将催化剂中氧化态钯转化为单质钯,在70℃恒温下,用盐酸和氧化剂NaClO3选择性浸出钯.本文比较了几种浸出方法的结果,考察了HCl-NaClO3浸出体系的几个因素对钯浸出的影响,确定了最佳浸出条件.实验结果表明,HCl-NaClO3浸出体系在优化条件下能完全浸出催化剂中的钯,该方法可以用于钯的回收和对催化剂中的钯进行定量分析. 相似文献
428.
Steven Piper Wen-Yuan Huang Marc Ribaudo 《Journal of the American Water Resources Association》1989,25(6):1217-1230
ABSTRACT: The potential surface water and ground water quality tradeoff implications from the nonpoint source provisions of the 1987 Water Quality Act are investigated in this paper using a national linear programming model developed at Iowa State University and modified by the Economic Research Service and the Leaching Evaluation of Agricultural Chemicals (LEACH) Handbook developed by the U.S. Environmental Protection Agency. The linear programming model is used to maximize net farm revenue using optimal combinations of crop rotations and tillage practices for each region of the United States given natural resource constraints. The LEACH handbook is used to determine the relative potential for pesticides to leach below the root zone for different soil types, hydrologic conditions, pesticides used, and tillage practices. The results indicate that imposing a surface water quality erosion constraint aimed at reducing sediment concentrations results in a larger decrease in farm income than imposing a uniform 5 ton per acre per year erosion constraint. Both constraints could result in regional improvement in ground water quality in some regions of the country while decreasing ground water quality in other regions. 相似文献
429.
430.
文章利用柠檬酸、硝酸以及硝酸和过氧化氢混合液对污泥进行淋滤处理,研究了污泥中重金属Cr、Cu的去除率,实验结果表明,混合淋滤优于单独淋滤,随着溶液浓度和淋滤量的增大,重金属去除率也呈增大趋势。在柠檬酸浓度为0.5mol/L,硝酸和过氧化氢混合液浓度为1.0mol/L。淋滤量为1000ml/kg的混合淋滤条件下,污泥中Cr、Cu去除率可以分别达到70.97%、90.33%,经处理后的污泥符合国家污泥农用标准。 相似文献