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41.
Ari Roisenberg Maria Paula C. Marimon Antonio P. Viero 《中国地球化学学报》2006,25(B08):121-121
Fluoride anomalies (up to 11 mg/L) have been detected in the porous confined Santa Maria Aquifer (Guarany Aquifer System) in the central region of Rio Grande do Sul State, southern Brazil, leading to endemic fluorosis. Two hypotheses are investigated concerning the fluoride origin: contamination by long-term phosphate-fertilizer application due to extensive tobacco plantation or lithogeochemical affiliation from regional rocks. The results are discussed based on statistical and geochemical modeling and stable isotope data of water, nitrate and sulfate. Field monitoring of phreatic and confined aquifer during two years and laboratory leaching and retention experiments were performed. Regional statistical analysis (factorial and cluster analysis) on the basis of 350 wells discriminates four different hydrochemical groups in the confined aquifer, considering magnesium, calcium bicarbonate, sodium chlorinate and sodium bicarbonate as specific parameters. The last two groups reach higher fluoride contents and represent deeper aquifer levels where geochemical modeling shows carbonates (calcite and dolomite) are of super-saturation. The laboratory experiments confirmed that local soils with high CTC and aluminum contents (Udults) represent an efficient geochemical barrier, preserving the aquifer from fluoride contamination and supporting remediation strategies for fluoride removal. δ^18O and δD groundwater data and the local meteoric water line (LMWL) indicate that local precipitation is the main groundwater recharge source in the area. 相似文献
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所研制的高钾系列复混喷施肥其成份以KNO3为主,含微量营养元素。应用试验表明,该喷施肥具有成本低,肥效高,经济效益显著的特点,具有推广应用价值。 相似文献
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利用不溶性钾矿提钾的研究现状及展望 总被引:17,自引:0,他引:17
简要介绍了我国和世界钾盐资源的分布及钾的供需状况,以及缓解我国缺押局面的主要途径,着重综述了我国不溶性钾矿资源状况和国内外利用不溶性钾矿提钾的研究现状和工业应用成果;最后阐述了利用不溶性钾矿提钾工业中存在的问题及其发展前景。 相似文献
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气候变暖对土壤化肥用量和肥效影响的实验研究 总被引:3,自引:0,他引:3
气候变暖对土壤肥料施用量和肥效有重要影响,通过对土壤分期增施3种水平的尿素实验,测定土壤中速效氮含量的动态变化,研究土壤肥效对温度的反应,结果表明,温度升高,土壤中速效氮释放量增大,释放速度加快,释放周期缩短,在450-1125kg/ha施肥水平下,每增温1℃氮释放量平均增加4%,释放周期缩短3.6天,同时,施肥量愈大,速效氮释放也愈大,释放速度愈快,因此,在气候变暖的条件下,需相应增加施肥总量和 相似文献
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Nitrous oxide emissions from fertilized and unfertilized soils in a subtropical region (Andalusia,Spain) 总被引:1,自引:0,他引:1
Field measurements of N2O emission rates were carried out from August until October 1982 in a subtropical region in Europe, i.e. in Andalusia, Spain. The measurements were performed by using an automatic sampling and analysis technique allowing the semi-continuous determination of N2O emission rates. The N2O emission rates were positively correlated to the soil surface temperature and exhibited a diurnal rhythm with maximum rates in the afternoon and minimum rates in the early morning with average values of 1 g N2O–N/m2/h for the grass lawn and 15 g N2O–N/m2/h for cultivated land. Application of urea and ammonium nitrate resulted in elevated N2O emission rates when compared to the unfertilized control. The loss of fertilizer-nitrogen as N2O was 0.18% for urea and 0.04% for NH4NO3 which compares very well with data obtained in a temperate climate (Germany). The total source strength of fertilizer-derived N2O is estimated to be 0.01–2.2 Tg N2O–N per year. The N2O flux from unfertilized natural soils may be as high as 4.5 Tg N2O–N, indicating that the N2O emission from soils contributes significantly to the global N2O budget. 相似文献
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