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141.
Nitrate pollution and its distribution in the groundwater of Srikakulam district, Andhra Pradesh, India 总被引:3,自引:0,他引:3
Nagireddi Srinivasa Rao 《Environmental Geology》2006,51(4):631-645
The complex depositional pattern of clay and sand in most of the areas controlled the vertical and lateral movement of nitrate in groundwater. The variation of nitrate concentration at different groundwater levels and the lateral distribution of nitrate in the groundwater at two sites indicated the filtration of nitrate by clayey formations. A rural agricultural district located in the Vamsadhara river basin, India was selected for studying the lateral and vertical distribution of nitrate in the groundwater and the association of nitrate with other chemical constituents. The nitrate concentrations in the groundwater are observed to vary between below detectable limit and 450 mg NO3/L. The sources for nitrate are mainly point sources (poultry farms, cattleshed and leakages from septic tanks) and non-point sources (nitrogenous fertilisers). The nitrate concentrations are increased after fertiliser applications. However, very high concentrations of nitrate are derived from animal wastes. Relatively better correlations between nitrate and potassium are observed (R = 0.74 to 0.82). The better relationship between these two chemical constituents in the groundwater may be due to the release of potassium and nitrate from both point and non-point sources. The nitrate and potassium concentrations are high in the groundwater from clayey formations. 相似文献
142.
M.A. Bouhifd L. Gautron V. Malavergne D. Andrault 《Physics of the Earth and Planetary Interiors》2007,160(1):22-33
The partition coefficients of potassium, DK, between molten sanidine, KAlSi3O8, and molten roedderite, K2Mg5Si12O30, with FeS-rich alloy and pure Fe metal liquids have been investigated in a multi-anvil press, between 5 and 15 GPa, at a temperature of 2173 K, and at an oxygen fugacity between 0.5 and 3 log units below the iron-wüstite (IW) buffer. No pressure dependence of the DK coefficients in sulphur-free and sulphur-bearing systems was found within the investigated pressure range. We also observed minor effect of the silicate melt composition for an nbo/t (non-bridging oxygen to tetrahedral cation ratio) higher than 0.8 ± 0.4. In contrast, the partitioning of potassium varies strongly with the metallic phase composition, with an increase of K-solubility in the metallic liquid for high sulphur and oxygen contents.We review all available high-pressure data to obtain reliable DK coefficients for the interaction between molten silicates and Fe-alloy liquids at pressures and temperatures relevant to those of core formation in a terrestrial magma ocean. The dominant controlling parameters appear to be the temperature and the chemical composition of the metallic phase, with DK coefficients significantly increased with temperature, and with the sulphur and oxygen contents of the Fe-alloy liquid. Our considerations distinguish two extreme cases, with an S-free or S-bearing iron core, which yield K contents of ∼25 or ∼250 ppm, respectively. These two extreme values have very different consequences for thermal budget models of the Earth's core since its formation. 相似文献
143.
硫酸钾是一种有着广泛应用的工业原料和农业肥料,其生产技术主要是通过海水或卤水中的硫酸盐与氯化钾反应制得。我国盐湖资源和盐类储量极其丰富,这为硫酸钾的制备生产提供了更多途径。但对于不同水化学类型的盐湖,需采取不同的提钾制备硫酸钾工艺路线。在以往盐湖钾盐提取和硫酸钾生产技术研究的基础上,针对碳酸盐型盐湖扎布耶盐湖中钾盐和硫酸钾的提取和制备方案进行了论述及设计,并指出了蒸发结晶法、化学沉淀法和吸附及离子交换法等几种方法在技术上都有其可行性。但在工业生产中可以考虑将这几种方法有机结合,以达到钾的最大富集,降低硫酸钾生产成本,并有利于保护环境。 相似文献
144.