生态环境学报 ›› 2021, Vol. 30 ›› Issue (10): 2076-2084.DOI: 10.16258/j.cnki.1674-5906.2021.10.014

• 研究论文 • 上一篇    下一篇

干旱区绿洲耕层土壤重金属铬含量的高光谱估测

王雪梅1,2(), 玉米提∙买明1, 毛东雷1,2, 梁婷3   

  1. 1.新疆师范大学地理科学与旅游学院,新疆 乌鲁木齐 830054
    2.新疆维吾尔自治区重点实验室(新疆干旱区湖泊环境与资源实验室),新疆 乌鲁木齐 830054
    3.新疆师范大学科研处,新疆 乌鲁木齐 830054
  • 收稿日期:2021-05-03 出版日期:2021-10-18 发布日期:2021-12-21
  • 作者简介:王雪梅(1976年生),女,教授,博士,硕士研究生导师,研究方向为干旱区资源环境遥感技术应用研究。E-mail: wangxm_1225@sina.com
  • 基金资助:
    国家自然科学基金项目(41561051);新疆维吾尔自治区自然科学基金项目(2020D01A79)

Hyperspectral Estimation of Heavy Metal Chromium Content in Arable Soil of Arid Area Oasis

WANG Xuemei1,2(), YUMITI∙Maiming 1, MAO Donglei1,2, LIANG Ting3   

  1. 1. College of Geographic Science and Tourism of Xinjiang Normal University, Urumqi 830054, China
    2. Xinjiang Uygur Autonomous Region Key Laboratory (Xinjiang Arid Lake Environment and Resources Laboratory), Urumqi 830054, China
    3. Scientific Research Department of Xinjiang Normal University, Urumqi 830054, China
  • Received:2021-05-03 Online:2021-10-18 Published:2021-12-21

摘要:

土壤重金属铬含量的高光谱估测技术较传统测量方法具有无污染、方便快捷进行动态监测的优势。对新疆渭干河-库车河三角洲绿洲耕层土壤98个样品的原始光谱反射率R分别进行倒数1/R、对数lg(R)、倒数对数lg(1/R)以及微分变换。不同处理结果与实测土壤重金属铬含量进行相关分析从而筛选出具有极显著相关的特征波段(P<0.001)。以不同变换处理下的特征波段反射率作为自变量,土壤铬含量为因变量,采用多元线性逐步回归、偏最小二乘回归、BP神经网络和随机森林回归方法构建土壤重金属铬含量的高光谱估测模型,并对最优估测结果进行克里格空间插值。结果表明,(1)原始光谱反射率的微分变换处理可有效提升光谱与土壤重金属铬含量之间的敏感性,其中经微分变换后的土壤光谱反射率与铬含量的相关系数由0.487显著提高到0.669(P<0.001)。(2)综合比较各模型的训练集和验证集估测结果,经倒数对数一阶微分[lg(1/R)]′处理后的BP神经网络模型具有较高的估测精度和很强的稳定性,可作为研究区土壤重金属铬含量的最优估测模型,其决定系数(Rd2)在0.8以上,均方根误差(RMSE)小于6.5,相对分析误差(RPD)大于2。(3)研究区土壤重金属铬含量具有中等空间变异性,低含量区域主要分布在新和县和沙雅县的外缘地带,而位于库车市东北部区域的耕层土壤铬含量达到最高水平。受人类活动影响该绿洲的土壤污染问题日趋严重,耕层土壤重金属铬含量呈现出较高含量的空间分布。

关键词: 土壤铬, 高光谱估测, 特征波段, 多元线性逐步回归, 偏最小二乘回归, BP神经网络, 随机森林回归

Abstract:

Compared with the traditional surveying method, the hyperspectral method for estimating the content of heavy metal chromium in soil has the advantages of non-pollution, convenient and rapid dynamic monitoring. The inverse 1/R, logarithm lg(R), logarithm lg(1/R) and differential transformation of the original spectral reflectance R of 98 soil samples from the delta oasis of Weigan-Kuqa River in Xinjiang were carried out respectively. Correlation analysis was conducted between the results of different treatments and the measured soil heavy metal of chromium content, so as to screen out the characteristic bands with extremely significant correlation (P<0.001). With the characteristics of band reflectance under different transformation processing as the independent variable, the soil chromium content as the dependent variable, using multiple linear stepwise regression, partial least-squares regression and BP neural network and regression method to build the random forest soil heavy metal chromium content of high spectral estimation model, and conduct the optimal estimate result Kriging interpolation space. The results showed that: (1) Differential transformation of original spectral reflectance could effectively improve the sensitivity between spectral reflectance and soil heavy metal chromium content, and the correlation coefficient between spectral reflectance and soil heavy metal chromium content after differential transformation was significantly increased from 0.487 to 0.669 (P<0.001). (2) Comprehensively compare the estimation results of the training set and the validation set of each model, the inverse logarithms first-order differential [lg(1/R)]' after being processed of BP neural network model has high estimation precision and strong stability, can be used as the optimal estimate model of soil heavy metal chromium content in the study area, the decision coefficient (Rd2) is over 0.8, the root mean square error (RMSE) is less than 6.5 and residual predictive deviation (RPD) is greater than 2. (3) Soil heavy metal chromium content in the study area is showed moderate spatial variability. The low-content areas were mainly distributed in the outer edge of Xinhe County and Shaya County, while the topsoil chromium content in the northeastern area of Kuqa City reached the highest level. Due to the influence of human activities, the soil pollution of the oasis has become more and more serious, and the content of heavy metal chromium in surface soil of farmland shows a relatively high spatial distribution.

Key words: soil chromium, hyperspectral estimation, characteristic band, multiple linear stepwise regression, partial least squares regression, BP neural network, random forest regression

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