土壤硝酸盐氮的空间变异特征及影响因素分析

为了掌握土壤中硝酸盐氮的空间变异性规律，为硝酸盐污染土壤控制与修复提供依据，以东北某农业灌区为例，利用地质统计方法进行土壤硝酸盐氮的空间变异特征及影响因素分析。研究结果表明：土壤硝酸盐氮的空间变异性显著，变异系数达到82.88%以上。第一层土壤硝酸盐氮在南北向空间上存在严格的自相关性，空间变异的结构性成分比例较高；第二、三层位土壤硝酸盐氮空间变化接近分形布朗运动；第四层位土壤硝酸盐氮在各方向上都具有较高的随机性。总体土壤硝酸盐氮质量分数由西向东逐渐递减，在浑河中下游以及细河附近土壤硝酸盐氮质量分数偏高。不同影响因素对于硝酸盐氮的空间变异特征影响不一致：土壤硝酸盐氮质量分数与有机质质量分数的空间分布趋势一致；不同土壤类型中，水田环境中土壤硝酸盐氮随着深度线性递减，而其他类型土壤中硝酸盐氮质量分数在表层向下递减后有一个回升现象，这与它们各自所处的环境特点有关，而地表壤土和砂土富含硝酸盐。

Spatial Variability of Soil Nitrate Nitrogen and Its Influencing Factors

In order to understand the spatial variability of nitrate nitrogen in soil and provide a basis for control and remediationof nitrate contaminated soil,taking one typical agricultural irrigation area in Northeast China as an example,we analyzed the spatial variability characteristics and influencing factors of nitrate nitrogen in soil by geo-statistical methods.The results show that the spatial variation of soil nitrate nitrogen is significant,and the coefficient of variation is above 82.88％.There is strict autocorrelation of soil nitrate in the north-south direction of the first layer soil,the structural component of spatial variation is high.The spatial variation of nitrate in the second and third layers of soil is in a similar way as a fractal Brown movement,and the nitrate content of the fourth layer of soil is changed randomly in all directions.The total content of soil nitrate nitrogen decreases from the west to the east,and the content of soil nitrate were both high in the lower reaches of Hunhe River and near the Xihe River.The effects of different factors on the spatial variation of nitrate nitrogen are different.The content of nitrate in soil is consistent with the spatial distribution of organic matter content.The soil nitrate nitrogen in paddy field decreases linearly with depth,while the content of nitrate nitrogen in other types of soil has a rebounce after a downward decline,which is associated with the soil environmental characteristics with surface loam and sandy soil rich in nitrate.