江西鄱阳湖平原区农田土壤微量元素空间分异特征及其影响因素

Spatial variability characteristics and impacting factors of soil trace elements in Poyang Lake plain,Jiangxi of China

【目的】开展土壤微量元素空间分异及其影响因素的分析,能更客观地阐明土壤微量元素变化的内在机理,对田间土壤肥力的有效管控和保障人类健康、保护土壤生态环境具有重要意义。【方法】在江西省丰城市鄱阳湖平原农田区,采用网格布点法布设283个采样点,每个采样点取0-20 cm表层土壤,对样点数据用三倍标准差法剔除异常值20个,实际利用样点数为263个,分析了土壤样品pH、质地、氮、磷、钾和硼(B)、锰(Mn)、钼(Mo)、硒(Se)、碘(I)、氟(F) 6种微量元素的含量。采用地统计学理论、方差分析、相关分析以及回归分析方法,对鄱阳湖平原区农田土壤6种微量元素的含量、空间分布特征及其影响因素进行分析。【结果】B、Mo含量均值处于丰富与上限值之间;Mn含量均值为330.24 mg/kg,处于缺乏水平;Se、I含量均值处于适量水平;F含量均值为474.59 mg/kg,处于边缘水平;6种微量元素含量均为中等程度变异,但各元素含量变异程度有所差异。B、Mn、Mo元素的最优插值模型为指数模型,Se、I、F均为球状模型。I元素的块金效应<25%,其他5种微量元素处于27.09%~41.77%。6种微量元素含量的空间分布格局差异较为明显,除Se元素不缺乏外,其余5种微量元素均处在缺乏水平。B、Mn、F含量均受到土壤类型、耕层质地的显著影响,Mn、Mo含量与坡度、pH间均达到极显著相关水平,Mn、Se、I含量与全磷含量显著相关,坡向与到河流的距离与6种微量元素含量未达到显著相关关系,其他影响因素仅对某些种元素表现出显著或极显著相关关系。在B、I含量的主要影响因素中,以耕层质地的影响最大;在Mn、Mo元素含量的主要影响因素中,以pH的贡献率最高;Se元素含量与土壤类型、全磷、坡度、高程之间达到显著或极显著相关水平,以全磷的影响程度最高;F元素含量与土壤类型、耕层质地、全氮含量相关显著,且全氮为主要影响因素。【结论】1)研究区域土壤B、Mo的含量总体较高,I、Se含量适量偏上,Mn总体上较为缺乏,F处于边缘水平;6种元素含量均为中等程度变异。2)土壤微量元素B、Mn、Mo的最优插值模型为指数模型,Se、I、F则为球状模型;除I具有强烈的空间自相关外,其余5种元素表现为中等程度的空间自相关。3)微量元素含量影响因素中,坡向、到河流的距离与各元素含量间未达到显著相关关系;B、I含量均受耕层质地的影响最大,Mn、Mo含量主要受pH的影响,Se含量主要受全磷的影响,F元素含量则主要受全氮的影响。

【Objectives】Conducting analysis of spatial variation and impacting factors of trace elements and understanding the interior mechanism of the phenomenon are needed for the effective management of soil fertility,maintaining of human health and protection of soil ecological enviroment.【Methods】Using grid placement method, 283 soil samples(0–20 cm) were collected in Poyang Lake plain, Jiangxi Province. 20 samples with abnormal values beyond triple folds of standard deviation were screened off. The pH, texture, N, P, K and 6 trace element(B, Mn, Mo, Se, I, F) contents were determined. Using geostatistic theory, variance analysis,correlation analysis and regression analysis methods to analysis the relationship among the trace element contents,spatial distribution variation and the impacting factors were analyzed.【Results】The average contents of B and Mo are between abundant and upper limit. The Mn is 330.24 mg/kg, which is deficient. The Se and I are at moderate level. And the F is 474.59 mg/kg at marginal level. All the 6 elements have moderate variation, but the variation degree of each element is different. The optimal interpolation models of B, Mn and Mo are exponential,while Se, I and F are spherical. The nugget effect of I is less than 25%, while the other five elements are between27.09% and 41.77%. The spatial distribution pattern of the six trace elements are comparatively different. Except that the content of Se isn’t deficient in the whole area, the other five elements all are deficient. B, Mn, F elements are affected by soil type, topsoil texture significantly. The correlation between Mn, Mo and slope, pH reached extremely significant levels. Mn, Se, I and the total P showed significant correlation. There are no correlation between the slope direction and the distance to the river with the six elements. Other factors only show significant or extremely significant correlation with a few elements. The topsoil texture has the greatest influence to B and I among their main factors, pH contributed the most to the content change of Mn and Mo among the main factors.The content of Se reach significant or extremely significant correlation with soil type, total P, slope and elevation,with the total P has the highest impact. The correlation between the content of F and soil type, topsoil texture and total N are significantly, and total N was the main influencing factor.【Conclusions】1) The total contents of soil trace elements B and Mo are relatively high of the study area, the I and Se are at the moderate level, and the Mn is relatively deficient overall. The F is at the marginal level. All the six elements show moderate variation. 2) The optimal interpolation models of soil trace elements B, Mn and Mo are exponential, while those of Se, I and F are spherical. Except for the consuming spatial autocorrelation of element I, the other five elements show moderate level. 3) Among the all impacting factors of trace elements, there is no significant correlation between the slope direction, the distance to the river with the content of each element. The element B and I are most affected by topsoil texture, pH influenced Mn and Mo mostly, Se is mostly impacted by total P, while F is mainly affected by total N.