农田尺度下土体硝酸盐淋失的随机模拟及其风险性评价
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* 国家自然科学基金项目(30390080和40401025);国家“863”计划项目(2004AA245020)资助


STOCHASTIC SIMULATION AND RISK ASSESSMENT OF NITRATE LEACHING AT FIELD SCALE
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    摘要:

    以田间试验为基础,对所建立的简化土壤水氮联合运移模型进行了验证。将条件模拟方法所得到的表层土壤饱和导水率(Ks)的随机场与该联合模型相结合,随机地模拟了冬小麦地1999年3月15日至6月10日这一时段的硝酸盐淋失情况。在总来水量为353.8mm、施N量为86.25kghm-2的情况下,2m土体硝酸盐淋失量最小值为N15.04kghm-2,最大值为N26.04kghm-2,分别占此段施肥量的17.4%和30.2%。以传统方法(Ks平均值)所得到硝酸盐淋失量作为对照,发现硝酸盐淋失量超过该值且概率大于70%的面积约占到田块总面积的20%左右。说明由于田间空间变异的作用,造成了硝酸盐淋失的巨大差异,故不能用传统的方法来代替,因为这样做就掩盖了地下水可能造成硝酸盐污染的风险性。

    Abstract:

    In recent years, nitrate contamination of groundwater has become an increasing concern for the health of people in rural areas who consume groundwater daily in China, ecially in the North China Plain.Usually, a deterministic model with mean hydraulic parameters is used to estimate the nitrate leaching for the whole agricultural field.In fact, the quantities of nitrate leached are variable from place to place in the field because of the parameters are different, so the simulated results by the deterministic model using mean hydraulic parameters could not represent the field-wide nitrate leaching.The objective of this paper is to evaluate the effect of spatial variability of the surface soil saturated hydraulic conductivity (Ks) on nitrate leaching and to assess the risk of nitrate contamination.First, a soil water-heat-nitrogen simulation model was established and verified based on the field data.Second, a sequential Gaussian simulation method was used to get a random field of the surface soil Ks based on 117 observed values in the field.Finally, the joint model was coupled with the random field of the surface soil Ks, which was gained by a conditional simulation method.During the period from March 15 to June 10, 1999, nitrate leaching was stochastically simulated with the irrigation rate being 353.8 mm and the nitrogen fertilizer application rate being 86.25 kg hm-2.The accumulated quantities of the leached nitrate ranged from N 15.04 kg hm-2 to 26.04 kg hm-2 in the soil profile 2 m in depth, account ing for about 17.4% and 30.2% of the fert ilizer used during this period.The area with the probability of nitrate leaching exceeding the value obtained by the conventional method in the control being higher than 70% amounted to about 20%.It was implied that the soil spatial variability could result in change in nitrate leaching.The value obtained with the traditional method in the control could not be used because it obscured the risk of nitrate leaching.

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胡克林,李保国,黄元仿,陈德立,WhiteRE.农田尺度下土体硝酸盐淋失的随机模拟及其风险性评价[J].土壤学报,2005,42(6):909-915. DOI:10.11766/trxb200412160605 Hu Kelin, Li Baoguo, Huang Yuanfang, Chen Deli, White R E. STOCHASTIC SIMULATION AND RISK ASSESSMENT OF NITRATE LEACHING AT FIELD SCALE[J]. Acta Pedologica Sinica,2005,42(6):909-915.

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  • 收稿日期:2004-12-16
  • 最后修改日期:2005-06-24
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  • 在线发布日期: 2013-02-25
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