脱硫石膏改良宁夏典型龟裂碱土效果及其安全性评价

    Effect of typical takyr solonetzs reclamation with Flue flue gas desulphurization gypsum and its security assessment

    • 摘要: 脱硫石膏是燃煤烟气湿法脱硫的副产物,已广泛应用于盐碱地改良。宁夏地区龟裂碱土质地坚硬、渗透性差,不易改良利用。为了评价脱硫石膏改良宁夏地区典型龟裂碱土的有效性和可行性,以早熟粳稻"吉特605"为试验材料,在大田试验条件下,研究了脱硫石膏对土壤特性、水稻产量和品质的影响,以及脱硫石膏作为盐碱地改良剂的安全性。结果表明:施用脱硫石膏降低了土壤的pH值和碱化度;显著提高水稻产量(P<0.05),2013年水稻产量由2 333.3提高到3 317.4 kg/hm2;脱硫石膏对稻米品质的影响主要体现在整精米率、垩白度、垩白粒率、胶稠度和直链淀粉上,2013年加工品质中的整精米率由52.6%提高到59.7%;比较施用脱硫石膏和未施用脱硫石膏的籽粒中的重金属含量的变化,施用脱硫石膏的籽粒中重金属除Cr含量较高外,Cd、As、Hg、Pb含量均比对照低,且都符合联合国粮农组织和国家食品标准规定的人类摄入标准。综合评价脱硫石膏施用效果,以施用量3.15×104 kg/hm2作用效果显著。该研究为脱硫石膏改良龟裂碱土,提高资源利用率提供参考。

       

      Abstract: Abstract: Flue gas desulphurization (FGD) gypsum is an industrial waste, which is produced by coal-fired power plant based on limestone-gypsum with a novel wet device. Takyric solonetz, a typical subclass of alkali soil, is widely distributed in the north of Yinchuan Plain of Ningxia Autonomous Region, the west of Hetao Plain and the desert steppe in north Xinjiang in China. Due to the hard soil texture, poor permeability and difficult improvement, takyric solonetz has become the main factor severely affecting the development of local agriculture, and is expected to bring threat to the regional food security in the future. The present study was to evaluate the feasibility and effectiveness of FGD gypsum on improving the typical takyr solonetzs of Ningxia region. In 2013 and 2014, a comparative field experiment was conducted in the farmland of Qianjin Farm in Pingluo County, Ningxia region, China (106°13′-106°26′E, 38°45′-38°55′N) and the precocious japonica "Jite 605" was taken as the test material. Five application rates of FGD gypsum (0, 1.05×104, 2.10×104, 3.15×104 and 4.20×104 kg/hm2) were applied. Besides, the leaching amount (4.5×103 m3/hm2) was designed in combination with FGD gypsum. We investigated the changes in soil property and agricultural production as well as the safety of FGD gypsum as soil amendment. It showed that by using FGD gypsum stimulation, the soil pH value and ESP (exchangeable sodium percentage) decreased in the 0-20 cm soil layer, which were from 9.8 and 42.1% before experiment to 9.1 and 35.2% in 2013, and 8.3 and 25.7% after experiment in 2014, respectively. These changes facilitated the growth of rice, and thereby increased the rice yield and improved the quality of the plots treated with FGD gypsum. The rice yield increased by 2 333.3-3 317.4 kg/hm2. The amount of FGD gypsum used did not change much the rice grain weight, the milled rice, the brown rice rate and the chalky rate, while the head milled rice rate increased from 52.6% to 59.7%; the chalky grain rate and chalkiness degree were changed by the varying of the amount of FGD gypsum: it decreased from a peak value of 9.3% at 3.15×104 kg/hm2 FGD gypsum to 8.1% at first, and then increased gradually to 9.1%. The amount of FGD gypsum improved the appearance quality of rice, chalky rice rate but reduced the cooking quality of gel consistency. The results showed that the suitable amount of FGD gypsum applied to reclaim takyric solonetz farmlands and improve rice quality was 3.15×104 kg/hm2, which had obvious effect. The contents of metals i.e. chromium (Cr), arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb) in corn grains were quantified by the inductively coupled plasma mass spectrometry (ICP-MS). Comparing the metal contents in grains, when 3.15×104 kg/hm2 FGD gypsum was applied to cultivated paddy, the contents of almost all of the metals in the corn grains in the FGD gypsum-treated plots were the same to or lower than those in the control plot. Almost all of the metal contents were lower than the standard values set by pharmacopoeias for human intake. These results suggest that the proper use of FGD gypsum will be helpful to fertilize the soil, and thereby increase the production and improve rice quality. Moreover, the contents of the heavy metals in the soils well comply with the Hygienic Standard for Grains in China (GB/T2715-2005), which implies that FGD gypsum will not deteriorate the soil environmental quality. The findings of this study will provide technical support for improving the newly reclaimed takyric solonetz farmlands as well as data support for improving the rice quality.

       

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