Incorporation of auxiliary information in the geostatistical simulation of soil nitrate nitrogen
Incorporation of auxiliary information in the geostatistical simulation of soil nitrate nitrogen
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DOI：
10.2136/vzj2005.0030
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发表时间：
2006-02-01
影响因子：
2.8
通讯作者：
Lamsal, S
中科院分区：
文献类型：
--
作者：
Grunwald, S;Goovaerts, P;Lamsal, S
在佛罗里达州中北部，由于大面积排水良好的海洋石英砂覆盖在多孔石灰岩材料上，再加上高降水率，硝酸盐进入含水层的潜在风险很高。我们的目标是估计佛罗里达州中北部圣达菲河流域土壤 NO3-N 的时空分布。我们对土壤 NO3-N 进行了空间分布的天气和季节采样（2003 年 9 月 - 潮湿的夏季/秋季，2004 年 1 月 - 干燥的冬季，2004 年 5 月 - 干燥的春季）。使用有序逻辑回归推断流域内每个位置的 NO3-N 概率先验分布。解释变量包括环境空间数据集，例如土地利用、排水类别和佛罗里达含水层 DRASTIC 指数。然后使用指标克里金法更新这些先验概率，并通过顺序指标模拟生成土壤 NO3-N 空间分布的多重实现。交叉验证表明，当分析中纳入辅助信息时，并且使用指示克里金法代替普通克里金法来分析这些数据集时，会获得更小的预测误差，这些数据集的特征是存在极高的值和低于检测限的不可忽略的数据数量。 2003 年 9 月，由于大而强烈的热带风暴造成过度淋滤，NO3-N 值最低。总体而言，2004 年 1 月的 NO3-N 值较高，这可能是由于冬季作物和牧场施肥、植物吸收量低以及微生物转化率低造成的。尽管观测和估计的 NO3-N 值反映了季节性趋势，但我们发现所有季节土壤 NO3-N 持续较高的区域。这些领域是实施最佳管理实践的主要目标。
In north-central Florida the potential risk for movement of nitrate into the aquifer is high due to the large extent of well-drained marine-derived quartz sand overlying porous limestone material coupled with high precipitation rates. Our objective was to estimate spatio-seasonal distributions of soil NO3-N across the Santa Fe River Watershed in north-central Florida. We conducted spatially distributed synoptic and seasonal sampling (September 2003 - wet summer/fall season, January 2004 - dry winter season, May 2004 - dry spring season) of soil NO3-N. Prior distributions of probability for NO3-N were inferred at each location across the watershed using ordered logistic regression. Explanatory variables included environmental spatial datasets such as land use, drainage class, and the Floridian aquifer DRASTIC index. These prior probabilities were then updated using indicator kriging, and multiple realizations of the spatial distribution of soil NO3-N were generated by sequential indicator simulation. Cross-validation indicated that smaller prediction errors are obtained when secondary information is incorporated in the analysis and when indicator kriging is used instead of ordinary kriging to analyze these datasets characterized by the presence of extreme high values and a nonnegligible number of data below the detection limit. The NO3-N values were lowest in September 2003 as a result of excessive leaching caused by large, intense tropical storms. Overall the NO3-N values in January 2004 were high and could be attributed to fertilization of crops and pastures, low plant uptake, and low microbial transformation during the winter period. Despite seasonal trends reflected by the values of observed and estimated NO3-N, we found areas that showed consistently high soil NO3-N throughout all seasons. Those areas are prime targets to implement best management practices.