GDAL在地理国情监测项目中的应用     

苏光日  范义鹏  张学之  姜淼 《东北测绘》2014,(1):86-88

在地理国情监测项目中,使用了大量的卫星遥感影像,这些卫星遥感影像单景数据都大于2GB。利用GDAL的快速高效的影像读取功能,动态分块读取图像,能够很好地处理这些大数据,采用扫描线算法提取地理国情监测项目的影像有效边界,实现影像接边和影像坐标范围检查。  相似文献   

Contamination of superficial sediments by heavy metals and iron in the Bizerte lagoon,northern Tunisia     

Amor Ben Garali  Mohamed Ouakad  Moncef Gueddari 《Arabian Journal of Geosciences》2010,3(3):295-306

According to the norms adopted by the National Network of observation of the marine life quality (RNO 1997) and US National Oceanic and Atmospheric Administration (US NOAA 1999), the superficial sediments of the Bizerte lagoon (northern Tunisia) show a contamination by nickel, which is the probable consequence of the closeness to the industrial zone, and by lead, the result of detrital material rich in lead of the geological lands of Jbel Kchabta and Jbel Messeftine. In the lagoon southern and eastern sectors, the contamination of superficial sediments is essentially by copper, zinc, nickel and iron. This pollution is related, on one hand, to the rejections of the steelworks El Fouledh and the military arsenal, and on the other hand, to Menzel Bourguiba waste disposal. The rest of the lagoon is exempted from any metallic contamination of the surface sediments. The enriched zones in manganese and zinc correspond to the higher contents in kaolinite and in smectite. Positive correlations were recorded between the percentage in fine fraction on the one hand, and the sedimentary contents in TOC, total nitrogen and heavy metals on the other hand. The majority of the analysed elements are “argilophilous” except zinc and manganese, which are clayey organophile. These results show that this lagoon receives concentrations in anthropogenic metals that risk provoking more or less important disruptions, which are harmful and irreversible on the fauna and flora of this lagoon and on the whole ecobiological equilibrium.  相似文献   

Summanen structure: Further geological and geophysical evidence of a meteorite impact event in Central Finland     

Satu Hietala  Jarkko Jokinen  Jouni Lerssi  Matti Niskanen  Lauri J. Pesonen  Jüri Plado 《Meteoritics & planetary science》2023,58(7):1002-1017

The Summanen structure is located in Central Finland and is one of Finland's 12 known meteorite impact structures. In 2017, the discovery of Summanen was based on numerous shatter cone boulders with planar deformation features (PDFs) and a circular electromagnetic anomaly, which is 2.6 km in diameter. The site was revisited in 2020 and 2022, and shatter cone-bearing outcrops were discovered. PDFs and feather features were identified in samples from these outcrops. A total of 38 PDF sets in 27 quartz grains resulted in rational crystallographic orientations concentrating on {10$\overline{1}$4}, {10$\overline{1}$3}, {10$\overline{1}$2}, and {11$\overline{2}$2}, implying shock pressures of 2–20 GPa. Gravity measurements were taken, and the electrical conductivity of the structure was studied. The gravimetric results revealed a circular negative anomaly of about 4 km in diameter, with an amplitude of −3.5 mGal. Excluding the gravitational effect of water and Quaternary sediments reduces the anomaly to −1.6 mGal. A bowl-shaped conductive layer, likely containing relict saline water in the impact-fractured bedrock, was identified to a depth of 240 m. Topographic and bathymetric data were combined to determine the impact's effect and interpret the level of erosion. Cobbles of sedimentary sand- and siltstones were found on the coastline of Lake Summanen. Based on their similarity to those found in the Söderfjärden impact crater with a Cambrian age, it is likely that these rocks and post-impact infill are also of a similar age.  相似文献