| Inversion of Landsat 8 for soil heavy metals after terrain correction |
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| DOI：10.7606/j.issn.1000-7601.2019.01.02 |
| Key Words: soil heavy metals Landsat 8 OLI terrain correction warning assessment |
| Author Name | Affiliation | | WANG Hai-xiao | College of Geographical Sciences and Tourism, Xinjiang Normal University, Urumqi, Xinjiang 830054, China | | WANG Yong-hui | College of Geographical Sciences and Tourism, Xinjiang Normal University, Urumqi, Xinjiang 830054, China
2. Xinjiang Laboratory of Lake Environment and Resources in Arid Zone, Urumqi, Xinjiang 830054, China |
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| Abstract: |
| In order to quickly understand the pollution status and potential ecological risk of heavy metals in the Manas watershed, DEM data was introduced into Landsat 8 OLI for terrain correction, and mathematical transformations such as reciprocal, derivative, and logarithm were carried out. The PLSR prediction model of soil heavy metals was established by selecting the highest correlation between band reflectivity and concentration of heavy metals from each transformation. Additionally, the distribution of heavy metals in the study area was analyzed and using the ecological risk assessment method provided early warning for the study area. The results showed that: based on Landsat 8 OLI, the DEM data was introduced to correct the reflectivity. Taking the B1 band reflectivity and heavy metal Cu as an example, the coefficient of determination, R2, between the topographically corrected reflectance values and the measured soil Cu content increased from 0.46 to 0.52, which indicated that the apparent reflectance after topographic correction reflected the soil heavy metal condition better. The best prediction model for soil heavy metals was used to invert the corresponding soil heavy metal content, and the soil heavy metal ecological risk index was introduced to evaluate the soil heavy metal ecological risk in the study area. The risk level of heavy metals in soils generally showed a tendency to weaken gradually from southwestern region to northeastern area. The ecological risk of the order: recovery area (C area) > degraded area (B area) > lake into the lake (A area). In order to verify the prediction accuracy of soil heavy metal ecological risk warning based on remote sensing, the measured data of soil heavy metal content in the study area was also calculated by the heavy metal ecological risk index that showed consistent results. As a result, the distribution of heavy metals in the study area could be estimated by means of remote sensing. The results also indicated that the heavy metal pollution in the study area was above the alarm level, the ecological function had begun to degrade and the treatment of heavy metal pollution in the area should be strengthened. |
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